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Sample records for callovo-oxfordian argillo-carbonated sedimentary

  1. Organic geochemistry of the Callovo-Oxfordian argillo-carbonated sedimentary series of the East of the Paris basin and of England. Variabilities and paleo-environmental implications

    International Nuclear Information System (INIS)

    The Callovo-Oxfordian clay-stones from the East of the Paris basin are studied by ANDRA in order to test the feasibility of a possible storage of radioactive waste. The molecular analysis of their organic matter indicates that they can be considered as homogenous from their organic content point of view because they are characterized by only one molecular facies. However, the transition to the surrounding limestones is underlined by a major evolution of the molecular facies indicating a change and an increase of the variability of the deposition and diagenesis conditions. The evolution of the distribution of the plant bio-markers indicates, at the end of the Lower Oxfordian, a paleo-floristic change characterized by the increase of the proportion of Pinaceae (a conifer family) or their forerunners on the London-Brabant massif. This paleo-floristic evolution reflects a paleo-climatic change characterized by the increase of aridity at the global scale. Other complementary results get on other sedimentary series of similar ages highlight the occurrence of a period of water anoxia during the Middle Callovian which certainly happened on the major part of the Western Europe. This event could be at the origin of the crisis of the carbonate production at the Dogger/Malm transition. On the other hand, an experimental technique based on artificial maturation of extant plants has been developed and will allow the acquisition of new palaeo-chemo-taxonomic data. These data will contribute to a better interpretation of plant bio-marker assemblages in terms of palaeo-floristic composition. (author)

  2. Organic geochemistry of the Callovo-Oxfordian argillo-carbonated sedimentary series of the East of the Paris basin and of England. Variabilities and paleo-environmental implications; Geochimie organique des series argilo-carbonatees du Callovo-Oxfordien de l'Est du bassin de Paris et d'Angleterre: Variabilites et implications paleoenvironnementales

    Energy Technology Data Exchange (ETDEWEB)

    Hautevelle, Y

    2005-12-15

    The Callovo-Oxfordian clay-stones from the East of the Paris basin are studied by ANDRA in order to test the feasibility of a possible storage of radioactive waste. The molecular analysis of their organic matter indicates that they can be considered as homogenous from their organic content point of view because they are characterized by only one molecular facies. However, the transition to the surrounding limestones is underlined by a major evolution of the molecular facies indicating a change and an increase of the variability of the deposition and diagenesis conditions. The evolution of the distribution of the plant bio-markers indicates, at the end of the Lower Oxfordian, a paleo-floristic change characterized by the increase of the proportion of Pinaceae (a conifer family) or their forerunners on the London-Brabant massif. This paleo-floristic evolution reflects a paleo-climatic change characterized by the increase of aridity at the global scale. Other complementary results get on other sedimentary series of similar ages highlight the occurrence of a period of water anoxia during the Middle Callovian which certainly happened on the major part of the Western Europe. This event could be at the origin of the crisis of the carbonate production at the Dogger/Malm transition. On the other hand, an experimental technique based on artificial maturation of extant plants has been developed and will allow the acquisition of new palaeo-chemo-taxonomic data. These data will contribute to a better interpretation of plant bio-marker assemblages in terms of palaeo-floristic composition. (author)

  3. Complexation of europium(III) by organic extracts from Callovo-Oxfordian argillites

    Energy Technology Data Exchange (ETDEWEB)

    Brevet, L.; Grasset, L.; Ambles, A. [Univ. de Poitiers, Synthese et Reactivi te des Substances Naturelles, CNRS UMR 6514, 86022 Poitiers (France); Reiller, P.; Claret, F.; Amekraz, B.; Moulin, C. [CEA, CE Saclay, CEA/DEN/DANS/DPC/SECR, Labo ratoire de Speciation des Radionucleides et des Molecules, F-91191 Gif-sur-Yvette (France)

    2007-06-15

    The complexation behaviour of organic extracts obtained after acid alteration of Callovo-Oxfordian argillites toward europium (III) is studied in time resolved laser induced spectrofluorimetry. The presence of fluoride ions in one extract, originated from the dissolution of remaining silicates in HCl/HF, precludes the correct study. Nevertheless, the dialysis of the extract at 500 Da permits to obtain a clearer evolution of the complexation pattern. The fluorescence spectrum and decay are strikingly different the ones obtained on alkaline degradation products of the Callovo-Oxfordian argillite, and resemble more to a small organic molecule pattern.

  4. Sequential Extraction and Spectroscopic Characterisation of Organic Matter from the Callovo-Oxfordian Formation

    Energy Technology Data Exchange (ETDEWEB)

    Grasset, L.; Brevet, J; Schäfer, T; Claret, F; Gaucher, E; Albrecht, A; Amblès, A

    2010-01-01

    One site under consideration for the disposal of medium and high level, long lived radioactive waste is in the eastern part of the Paris Basin (Meuse/Haute Marne, France), where the National Radioactive Waste Management Agency (ANDRA) operates an underground laboratory. The sedimentary host formation is a 130 m thick, clay-rich Callovo-Oxfordian deposit ca. 350-550 m below ground in the selected area. The major fraction (>95%) of the organic matter (OM) is associated with minerals. In order to better understand the importance of OM on the chemistry of this formation, we have developed a protocol allowing extraction/fractionation of organic compounds in the rocks. The protocol is based on classical methods currently used for the isolation of humic substances from soils and for the separation of kerogen in ancient sediments using sequential extraction with solvents and water at different pH value. This allows us to the remove a large part of the minerals and to suspend almost all (>90%) of the OM (associated with residual recalcitrant minerals) in water. The OM can then be analysed via spectroscopic methods, such as mass spectrometry (MS), Fourier transform infra-red spectroscopy (FTIR), or C (1s) near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The molecular composition of the solvent-soluble, directly-extractable part shows the OM to be thermally immature. The solvent-soluble fractions obtained after acid and alkaline treatments are mostly polar in nature and have a high degree of aliphaticity. C(1s) NEXAFS analysis of water soluble organic fractions indicates a progressive increase in aliphaticity and a decrease in carboxylic/carbonyl groups with consecutive extraction steps.

  5. A laboratory investigation of thermally induced pore pressures in the Callovo-Oxfordian Claystone

    OpenAIRE

    Mohajerani, Mehrdokht; Delage, Pierre; Sulem, Jean; MONFARED, Mohammad; Tang, Anh Minh; Gatmiri, Behrouz

    2013-01-01

    In the framework of research into radioactive waste disposal, it was decided to investigate the thermally induce pore pressure occurring in the Callovo-Oxfordian claystone, a possible host rock in which the ANDRA underground laboratory of Bure (East of France) has been excavated. Thermal pore pressures appear in low permeability soils and rocks because the thermal expansion coefficient of water is significantly higher than that of the solid grains (Campanella and Mitchell; 1968 [1], Ghabezloo...

  6. Nature and reactivity of organic matter in argillaceous formations: example of the Callovo-Oxfordian of Bure (France)

    International Nuclear Information System (INIS)

    In carbon cycle models, it is admitted that less than 1% of produced organic carbon is transferred to the geological cycle as sedimentary organic matter (Tissot and Welte, 1984). Although, coal or petroleum source rocks are most well known, sedimentary organic matter also occurs in various concentrations throughout many different rock facies. Organic matter is therefore a witness of the record of environmental changes as well as biomass evolution through time. It is also a reliable tracer of diagenetic conditions, from sediment deposition to metamorphism and subsurface alteration. Especially in the case of argillaceous sediments, known for their potential proneness of organic matter, the study of fossil organic matter is able to unravel a large amount of information concerning the geological past (depositional conditions and preservation, paleo-environment, burial, thermal history) as well as the future (effects of induced thermal perturbation, oxidative alteration, biodegradation). We are presenting here data obtained on the Callovo-Oxfordian argillaceous formations of Bure (France), which are the target layers for the installation of a future laboratory. (authors)

  7. Hydrogen uptake and diffusion in Callovo-Oxfordian clay rock for nuclear waste disposal technology

    International Nuclear Information System (INIS)

    Highlights: • We estimated the H2(g) sorption capacity of Callovo-Oxfordian clay rock samples. • We compared H2 and N2 adsorption at different temperatures and pressures. • We estimated the H2(g) diffusion constants and mechanism at 25–300 K and 40 bar. • We worked at pressures and temperatures of interest for nuclear waste storage sites. - Abstract: The Callovo-Oxfordian clay-rich rock formation is currently considered as host rock barrier in the French geological repository facility for radioactive waste (Meuse/Haute-Marne). After the closure of the facility, hydrogen gas is expected to develop mainly from anaerobic corrosion of steel containers and other iron-containing structures. Gas pressure build-up could impact the safety of the repository. It is therefore important to acquire in-depth knowledge on the interaction between hydrogen gas and surrounding clay rock in terms of uptake ability and diffusion. Hydrogen uptake capacity was evaluated on dried clay rock samples: (i) at 20 K, to allow for hydrogen liquefaction and determine the maximal H2 uptake of the clay, and (ii) at typical pressure and temperature conditions expected to develop in the repository (up to 363 K and a hydrogen pressure of 40–60 bar). H2 absorption on the dried raw Callovo-Oxfordian start to saturate at about 30–40 bar, and the average adsorption above 40 bar is about 0.1% in weight. Quasi-elastic neutron scattering spectroscopy was used to study the diffusion mechanism of hydrogen gas in the clay rock at the microscopic scale and to determine hydrogen self-diffusion coefficients in the dry samples in the temperature range 25–300 K. Neutron data suggested that hydrogen diffuses in the dry clay rock according to Fick’s law. The findings reported in this work can help to better understand the behavior of H2 in clay rock samples

  8. A laboratory investigation of thermally induced pore pressures in the Callovo-Oxfordian Claystone

    CERN Document Server

    Mohajerani, Mehrdokht; Sulem, Jean; Monfared, Mohammad; Tang, Anh-Minh; Gatmiri, Behrouz

    2013-01-01

    In the framework of research into radioactive waste disposal, it was decided to investigate the thermally induce pore pressure occurring in the Callovo-Oxfordian claystone, a possible host rock in which the ANDRA underground laboratory of Bure (East of France) has been excavated. Thermal pore pressures appear in low permeability soils and rocks because the thermal expansion coefficient of water is significantly higher than that of the solid grains (Campanella and Mitchell; 1968 [1], Ghabezloo and Sulem; 2009 [2]). This phenomenon has clearly been observed in various in-situ heating tests conducted in Opalinus claystone in the Mont-Terri Underground Research Laboratory (URL) in Switzerland (HE-D test) and in Callovo-Oxfordian (COx) claystone in the Bure URL in France (TER test, Wileveau and Su; 2007 [3]) The processes of coring, transportation, storage and specimen trimming induce some desaturation in the sample. Due to the very low permeability (10-20 m2) of the COx claystone, a long period of time is necessa...

  9. Contributions to micromechanical model of the non linear behavior of the Callovo-Oxfordian argillite

    International Nuclear Information System (INIS)

    This work is performed in the general context of the project of underground disposal of radioactive waste, undertaken by the French National Radioactive Waste Management Agency (ANDRA). Due to its strong density and weak permeability, the formation of Callovo-Oxfordian argillite is chosen as one of possible geological barriers to radionuclides. The objective of the study to develop and validate a non linear homogenization approach of the mechanical behavior of Callovo-Oxfordian argillites. The material is modelled as a composite constituted of an elasto(visco)plastic clay matrix and of linear elastic or elastic damage inclusions. The macroscopic constitutive law is obtained by adapting the incremental method proposed by Hill. The derived model is first compared to Finite Element calculations on unit cell. It is then validated and applied for the prediction of the macroscopic stress-strain responses of the argillite at different geological depths. Finally, the micromechanical model is implemented in a commercial finite element code (Abaqus) for the simulation of a vertical shaft of the underground laboratory. This allows predicting the distribution of damage state and plastic strains and characterizing the excavation damage zone (EDZ). (author)

  10. Liner failure around a tunnel or a storage cell in Callovo-Oxfordian clay

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. In the framework of the feasibility studies for the storage of radioactive waste in a deep geological layer, the post-failure behaviour of the concrete liner of the galleries and storage cells may have a direct effect on long term safety. In fact, the failure of the liner will result in new loads on the canisters placed inside the works, and in the de-stressing of the Callovo-Oxfordian clays, which may lead to a change in the Excavation Damage Zone. These phenomenons are studied via numerical modelling, using properties derived from ANDRA's underground laboratory (CMHM) project. Two types of gallery geometries are analyzed: one with a thinner concrete liner and filled interior (the standard gallery); and another with a thick concrete liner filled with concrete canisters (the MAVL disposal cell). The Standard Gallery is filled with a Cam-Clay material after 100 years of creep, while the MAVL disposal cell is filled with 16 concrete canisters immediately after installation of the concrete liner. Progressive failure of the concrete liner due to time-dependent deformation of the surrounding rock (Callovo-Oxfordian clay) over a long period of time is analyzed. The analyses are carried out in two steps. In the initial simulations, the concrete liner is represented as a continuum strain-softening Mohr-Coulomb material. The locations of stress-induced fractures in the concrete are determined from this continuum model. The stress-induced fractures are then specified as pre-defined discontinuities in the concrete liner in subsequent dis-continuum simulations. In a dis-continuum model, the large deformations and movements of the concrete blocks as the liner disintegrates can be simulated without numerical problems. The Callovo-Oxfordian clay is represented as an elastic-plastic-viscous material using the Lemaitre constitutive relation. The majority of the simulations are carried out over 5,000 years of creep time, with a

  11. Impact of the landscape evolution on the hydraulic boundary conditions of the Callovo-Oxfordian formation

    Energy Technology Data Exchange (ETDEWEB)

    Teles, V.; Maugis, P.; Mouche, E. [CEA, CNRS Orme Merisiers, Lab Sci Climat and Environm, F-91191 Gif Sur Yvette, (France); Brulhet, J.; Wendling, J.; Vigneron, G. [ANDRA, F-92298 Chatenay Malabry, (France)

    2007-07-01

    The Callovo-Oxfordian formation in the Eastern part of France was recognized as a potential nuclear waste repository layer. The ANDRA (National Agency for Nuclear Waste Management) has launched a few years ago a research program that aims to define the mechanisms of importance in the impact of the surface environment evolution on the site hydrogeology. Based on mapping and dating results, ANDRA has quantified the geomorphological evolution of the Meuse/Haute-Marne site in the past and has estimated the future evolution over 1 million years. The Callovo-Oxfordian boundary conditions depend on the hydraulic heads in the two surrounding aquifers, the Oxfordian limestone above, and the Dogger one, below. Both aquifer outcrops are modified over the next million years. For the present study, the geo-morphologic evolution is considered independently of other processes and translated in the hydrogeological model in terms of changes in the hydraulic boundary conditions at the surface. The hydrodynamic simulations have been performed with the code Cast3M (implemented by CEA (Atomic Energy Commissariat)) using a mixed hybrid finite-element formulation. For these groundwater flow simulations, three modelled stages are presented: the Present, 500,000 years (500 Ky) and 10{sup 6} years (1 Ma) in the future. The landscape evolution is merely considered through the use of three different topographies on which the boundary conditions are applied. According to ANDRA predictions, at the Meuse/Haute-Marne site, the valley incisions on the Bure plateau will locally reach the Oxfordian limestone. Thus, the Oxfordian aquifer exhibits more changes due to topographic evolution than the Dogger aquifer. Hydrodynamic simulations show a significant impact of the valley incisions on the groundwater flow by the creation of local outlets to the Oxfordian limestone aquifer in the North of the area for the 1 My topography. It induces local perturbations of the saturation level. The global erosion

  12. Micro-mechanics based modeling of the Callovo-Oxfordian argillite mechanical behavior

    International Nuclear Information System (INIS)

    The present study is devoted to the development and validation of a non-linear homogenization approach of the mechanical behavior of Callovo-Oxfordian argillites. The material is modelled as an heterogeneous one composed of an elastoplastic clay matrix and of linear elastic or elastic damage inclusions. The macroscopic constitutive law is obtained by adapting the Hill-type incremental method [1]. The approach consists in formulating the macroscopic tangent operator of the material from the non-linear local behavior of its phases. Due to the matrix/inclusion morphology of the microstructure of the argillites, a Mori-Tanaka scheme is considered for the localization step. The developed model is first compared to Finite-Elements calculations and then validated and applied for the prediction of the macroscopic stress-strain responses of argillites. (authors)

  13. Coupled transport phenomena in a clay from a Callovo-Oxfordian formation

    International Nuclear Information System (INIS)

    Low permeability materials containing clay play an important role in practical life and natural environment. Indeed, the ability of clay soils to act as semi permeable membranes, that inhibit the passage of electrolytes, is of great interest. The major objective of this thesis is to evaluate the transport properties of natural clays and in particular coupled transports when a pressure gradient, an electrical field, a concentration gradient and a temperature gradient interact. The material is a compact argillite extracted in East France from a Callovo-Oxfordian formation which was supplied to us by ANDRA. NaCl was used as the main solute. Two series of experiments were performed to measure permeability, diffusion, conductivity, the electro-osmotic coefficient and the Soret coefficient. (author)

  14. The Callovo-Oxfordian of the Paris Basin: From its geological context to the modelling of its properties

    International Nuclear Information System (INIS)

    The French law from December 30, 1991 entrusted the French national agency for radioactive wastes (ANDRA) with the mission of assessing the feasibility of a deep geological repository in the clay-rich Callovo-Oxfordian formation of NE France (Meuse and Haute-Marne departements). A research program, coordinated by ANDRA and involving several university laboratories and other French organizations (CNRS, CEA, BRGM, INERIS, INPL, ENSMP) has permitted to gather a huge amount of information about the properties of the Callovo-Oxfordian formation of the eastern part of the Paris basin. These properties are summarized in this introductive paper: paleo-geography, bio-stratigraphy of ammonites, clay mineralogy and other minerals content, anisotropy of argillite beds, permeability and porosity, osmosis and thermal diffusion, chemistry of interstitial waters, fracturing.. (J.S.)

  15. Modelling the effective diffusion coefficient of anions in Callovo-Oxfordian argillite knowing the microstructure of the rock

    International Nuclear Information System (INIS)

    After having presented the issue of radioactive waste storage, the concept of geological storage and its application in the Meuse/Haute-Marne underground laboratory, and described the Callovo-Oxfordian geological formation and the argillite transport properties, this research thesis aims at developing a prediction of these properties at a macroscopic scale for water and anions. A first part presents the different experimental means implemented to acquire the diffusion coefficients for the studied materials (Callovo-Oxfordian argillite and purified Puy illite), and the spatial organisation of minerals by LIBS probe-based mapping to highlight a relationship between rock microstructure and its transport macroscopic properties. The next part presents the models which have been developed at the nanometer and micrometre scale to predict the diffusion coefficients. Experimental results are then compared with computed values

  16. Osmotic flow and over pressures within the Callovo-Oxfordian argillite in the eastern part of the Paris Basin

    International Nuclear Information System (INIS)

    A middle Jurassic shale, the Callovo-Oxfordian argillite (420-560 m b.g.), is currently being intensively investigated at the ANDRA site, about 300 km eastern from Paris, and particularly with respect to its hydrogeological and hydrochemical properties. The argillite rests between the Oxfordian Limestone above and the Dogger Limestone below. Observations from the different deep boreholes located at the site can be summarized as follows: the measured apparent hydraulic head across the Callovo-Oxfordian argillite show excess values of several tens of meters in comparison to the upper and lower aquifers, a fact which is referred to as anomalous overpressure in the shale literature; the salinity of the pore water in the Callovo-Oxfordian argillite and the Dogger is much larger than that of the Oxfordian. The salinity levels in the Callovo-Oxfordian and the Dogger are similar. Among all physical processes which can be proposed as explanation for the formation of overpressure in shales, osmosis driven by a chemical potential (total dissolved solids) gradient is a possible candidate. As a matter of fact, the presence of contrasts in water composition and clay minerals content, as observed here, lead to osmotic effects. This paper presents the results of simulations using steady-state approximations and transient simulations (software OSMO, a numerical simulator developed by the British Geological Survey). It is shown that based on the extensive database of argillite measurements applicable to the study (including porosity values, specific surface determinations, pore water compositions, and effective diffusion coefficients), the chemo-osmosis is a process which can at least explain partly the anomalous overpressures observed. (authors)

  17. Mobility of cesium through the Callovo-Oxfordian claystones under partially saturated conditions

    International Nuclear Information System (INIS)

    The diffusion of cesium was studied in an unsaturated core of Callovo-Oxfordian claystone, which is a potential host rock for retrievable disposal of high-level radioactive wastes. In-diffusion laboratory experiments were performed on rock samples with water saturation degrees ranging from 81% to 100%. The analysis of both cesium concentration monitoring in the source reservoir and postmortem cesium rock concentration profile of the samples was carried out using a chemical-transport code where the sorption of cesium was described by a multi-site ion-exchange model. The results showed that cesium exhibited a clear trend related to the saturation degree of the sample. The more dehydrated the rock sample, the slower the decrease of cesium concentration, and the thinner the penetration depth of cesium was. The effective diffusion coefficient (De) for cesium decreased from 18.5 *10-11 m2 s-1 at full-saturation to 0.3 * 10-11 m2 s-1 for the more dehydrated sample. This decrease is almost 1 order of magnitude higher than that for tritiated water (HTO), although a similar behavior could have been expected, since cesium is known to diffuse in the same parts of the pore space as HTO in fully saturated claystones. (authors)

  18. Investigating the swelling pressure of compacted crushed-Callovo-Oxfordian clay-stone

    International Nuclear Information System (INIS)

    This paper presents an experimental study on the swelling pressure of heavily compacted crushed Callovo-Oxfordian (COx) clay-stone at a dry unit mass ρd=2.0 Mg/m3 using four different methods: constant-volume, swell-reload, zero-swell and adjusted constant-volume method. Results show that the swelling pressure varies in the range of 1-5 MPa and depends significantly on the test method. From the constant-volume tests, it is observed that the swelling behavior during wetting is a function of the suction and depends on both the hydration paths and wetting conditions (e.g. vapor-wetting or liquid-wetting). The swelling pressure decreases significantly with saturation time. To identify the microstructure changes of specimens before and after wetting, mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) tests were performed. It is observed that, after wetting, the large inter-aggregate pores observed in the as-compacted specimen are no longer apparent; the whole pattern is characterized by a general swell of hydrated clay particles, rendering the soil more homogenous. Results from MIP indicated that wetting caused a significant reduction of the entrance diameter of the dominant inter-aggregate pores from 2.1 to 0.5μm whereas intra-aggregate pores were not significantly influenced. (authors)

  19. Investigation on the anisotropic mechanical behaviour of the Callovo-Oxfordian clay rock within the framework of ANDRA/GRS cooperation programme. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chun-Liang [Gesellschaft fuer Anlagen- und Reaktorsicherheit mbH (GRS), Koeln (Germany); Armand, Gilles; Conil, Nathalie [French Agence Nationale Pour la Gestion de Dechets Radioactifs (ANDRA), Chatenay-Malabry (France)

    2015-01-15

    An underground repository for disposal of radioactive waste is planned to be constructed in the sedimentary Callovo-Oxfordian argillaceous formation (COX) in France /AND 05/. The clay rock exhibits inherent anisotropy with bedding structure, which leads to directional dependences of the rock properties (e.g. mineralogical, physical, mechanical, hydraulic, thermal, etc.) with respect to the bedding planes. For the design of the repository and the assessment of its safety during the operation and post-closure phases it is necessary to characterise and predict the anisotropic properties and processes in the host rock, particularly in the excavation damaged zone (EDZ) near the openings. Within the framework of the bilateral cooperation agreement between the French National Radioactive Waste Management Agency (ANDRA) and the German Federal Ministry of Economics and Technology (BMWi), concerning the research activities in the Meuse/Haute-Marne Underground Research Laboratory (MHM-URL), a joint research programme was initiated by ANDRA and GRS in 2013 to investigate mechanical anisotropy of the COX clay rock for the purpose of precise characterization, better understanding and reliable prediction of the development of EDZ around the repository. This programme was funded by ANDRA under contract number 059844 and performed by GRS during the time period of November 2013 to December 2014. GRS gratefully acknowledges the financial support from and the fruitful cooperation with ANDRA.

  20. Investigation on the anisotropic mechanical behaviour of the Callovo-Oxfordian clay rock within the framework of ANDRA/GRS cooperation programme. Final report

    International Nuclear Information System (INIS)

    An underground repository for disposal of radioactive waste is planned to be constructed in the sedimentary Callovo-Oxfordian argillaceous formation (COX) in France /AND 05/. The clay rock exhibits inherent anisotropy with bedding structure, which leads to directional dependences of the rock properties (e.g. mineralogical, physical, mechanical, hydraulic, thermal, etc.) with respect to the bedding planes. For the design of the repository and the assessment of its safety during the operation and post-closure phases it is necessary to characterise and predict the anisotropic properties and processes in the host rock, particularly in the excavation damaged zone (EDZ) near the openings. Within the framework of the bilateral cooperation agreement between the French National Radioactive Waste Management Agency (ANDRA) and the German Federal Ministry of Economics and Technology (BMWi), concerning the research activities in the Meuse/Haute-Marne Underground Research Laboratory (MHM-URL), a joint research programme was initiated by ANDRA and GRS in 2013 to investigate mechanical anisotropy of the COX clay rock for the purpose of precise characterization, better understanding and reliable prediction of the development of EDZ around the repository. This programme was funded by ANDRA under contract number 059844 and performed by GRS during the time period of November 2013 to December 2014. GRS gratefully acknowledges the financial support from and the fruitful cooperation with ANDRA.

  1. Insights on desaturation processes based on the chemistry of seepage water from boreholes in the Callovo-Oxfordian argillaceous rock

    International Nuclear Information System (INIS)

    Seepage waters from boreholes were collected in the Meuse/Haute-Marne Underground Research Laboratory (NE France) in the Callovo-Oxfordian clay-rich host rock. Over the first months after the drilling of the boreholes, these waters were saltier than the waters collected later on, even in the boreholes that had been drilled without oxygen. These chemical composition variations give insights on the volume of rock affected by the loss of water around the boreholes. This data will help to characterize the desaturation processes in such a rock and the consequences with respect to the composition of the water that will fill the underground works after their closure. (authors)

  2. Analysis of pore pressure response of Callovo Oxfordian clay-stone to heating

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. One of the aims of the TED heater experiment at Bure is to perform a parameter identification of the thermo-hydro-mechanical properties of the Callovo-Oxfordian clay. A detailed description of the heater experiment can be found in the paper presented by N. Conil, also at this meeting. Three artificial heat sources are used to simulate heat generating waste canisters and are placed in three parallel horizontal boreholes. The heating process is carried out by using three heating phases with different amounts of heat release. The thermo-hydro-mechanical (THM) response of the Callovo-Oxfordian clay-stone is monitored by a large number of temperature and pore water pressure sensors as well as extensometers installed in the heater boreholes as well as in a couple of observation boreholes. One possibility to identify the THM parameters of the clay-stone is to perform a series of forward simulations by adjusting the THM input parameters until the calculation results fit best to the measured values at the different sensor locations. Given the large number of sensors to consider, doing this fitting process manually is a long and laborious task. Thus, an automatic parameter identification process has been applied. Parameter identification In this paper we focus on the analysis of the pore water pressure response to drilling and heating. For the process of parameter identification, an automatic procedure was used by applying the software 'optiSLang' which allows for optimizing nonlinear tasks that include many parameters. The software is able to offer a sampling-based sensitivity analysis to identify important parameters, to quantify the individual influence on the calculation results, and to generate a so-called best design approximating the measurement results taken in situ as good as possible. optiSLang changes input parameters within given ranges automatically and autonomously starts new calculations by triggering the

  3. Geostatistical application for the variability study of the Callovo-Oxfordian unit

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Since 1991 Andra has the mission to investigate the feasibility of creating a radioactive waste disposal inside a profound geological formation. In this framework and taking into account several researches already realized in-situ and close to the underground laboratory of Bure (Meuse's region), it is necessary to evaluate the petrophysical variability of the clay of the Callovo-Oxfordian. This evaluation will be realized through the application of geostatistical tools. This study begins with log and seismic information. The acoustic impedance measured at wells (named log-impedance) has been sampled in time, at the support of the seismic lines (1 millisecond). The seismic impedance obtained after geophysical inversion is compared to the log-impedance. The well-known geostatistical procedure, to predict the spatial continuity of litho-facies in the oil industry, is adapted here to evaluate the variability of the log-impedance. The results provided in this paper are based on one well and one 2-D seismic profile. Along the studied line, the 'seismic impedance' and 'log-impedance' are linked with a linear correlation coefficient of about 0.71. To study the spatial variability, experimental variograms are computed, bivariate along the vertical direction and univariate (seismic 'impedance') along the horizontal direction. These variograms are then fitted. A first bi-variable model with a correlation coefficient of the 0.73 has been used to perform the estimation. The corresponding standard deviation map, points out the fact that the variability depends on the distance to the core drill. At the core drill, the log impedance is known and therefore the standard deviation is equal to zero. Another model has been fitted corresponding to a linear correlation coefficient of 0.68. The resulting standard deviation map gives higher values far from the core drill. These computations highlight the

  4. Iron corrosion in Callovo Oxfordian argilite: From experiments to thermodynamic/kinetic modelling

    Science.gov (United States)

    de Combarieu, G.; Barboux, P.; Minet, Y.

    Many designs for high-level nuclear waste deep geological disposal include steel waste canister and low-alloy steel overpacks. The container and overpack corrosion products may affect the alteration kinetics of nuclear waste glass and contaminant retention properties due to mineralogical transformation in the surrounding clay. To better quantify the effect of corrosion on the mineralogical alteration of the clay, the present study reports the corrosion of pure iron in raw Callovo-Oxfordian argilite. Batch experiments have been carried out at 90 °C, from one to six months, under oxygen-free atmosphere. Iron corrosion kinetics and secondary mineral formation have been studied with quantitative XRD measurements. Chemical analyses have been performed by ICP-AES, ICP-MS and ionic chromatography. Eh and pH have also been monitored along with the reaction progress. The phases formed from the Fe release in solution are magnetite and Fe-rich silicate from the serpentine group (greenalite or cronstedtite) or chlorite. These phases are associated to the dissolution of quartz, illite and interstratified illite/smectite mixed layers. Solution analyses show that the Si, Fe, Mg and Al concentrations are controlled at a very low level by the precipitation of newly formed phases, although a noticeable pH increase (from 7 to 10 at 90 °C) is associated to iron corrosion. In the conditions of the experiments, the iron corrosion rate has been measured ( Riron = 6 × 10 -9 mol/m 2/s equivalent to 1.4 μm/year) and is in good agreement with previous works. The use of the geochemical code CHESS based on (i) solution analysis, (ii) mineral quantification and (iii) determination of kinetic data for iron corrosion allows to reproduce accurately this reaction-path. Fractionation of dissolved iron between iron silicate and magnetite can be correctly predicted, as well as the pH, Eh and other minerals stability.

  5. Analysis of Long-Term Anisotropic Convergence in Drifts Excavated in Callovo-Oxfordian Claystone

    Science.gov (United States)

    Guayacán-Carrillo, Lina-María; Sulem, Jean; Seyedi, Darius M.; Ghabezloo, Siavash; Noiret, Aurélien; Armand, Gilles

    2016-01-01

    The main purpose of this paper is to analyze the convergence measurements in drifts of the Underground Research Laboratory (URL) of the French National Radioactive Waste Management Agency (Andra), excavated in Callovo-Oxfordian claystone. These measurements show an anisotropic closure, which depends on the drift orientations with respect to the horizontal in situ stresses. This anisotropic character of the deformation is taken into account by assuming that the drifts section evolves following an elliptical shape. The characteristics of the deformed elliptical section are evaluated following the methodology proposed by Vu et al. (Rock Mech Rock Eng 46:231-246, 2013). Then, using the semi-empirical law proposed by Sulem et al. (Int J Rock Mech Min Sci Geomech Abstr 24:145-154, 1987), the convergence evolution is fitted independently for each axis of the ellipse. This method allows to distinguish two effects: the face advance and the time-dependent behavior of the ground. The results for the two drift orientations (along the major horizontal stress and perpendicular to it) show very close values for the parameters describing the time-dependent properties of the ground, the distance of influence of the face, and the extent of the decompressed zone around the drift. Finally, the model is validated by keeping these parameters as constants and by simulating the convergence data on a new drift. It is shown that with a period of about 40 days of convergence monitoring, the model can provide valuable insights for predictions of the convergence evolution in the long term.

  6. Geostatistical characterization of the Callovo-Oxfordian clay variability: from conventional and high resolution log data

    International Nuclear Information System (INIS)

    Andra (National Radioactive Waste Management Agency) has conducted studies in its Meuse/Haute-Marne Underground Research Laboratory located at a depth of about 490 m in a 155-million-year-old argillaceous rock: the Callovo-Oxfordian argillite. The purpose of the present work is to obtain as much information as possible from high-resolution log data and to optimize their analysis to specify and characterize space-time variations of the argillites from the Meuse/Haute-Marne site and subsequently predict the evolution of argillite properties on a 250 km2 zone around the underground laboratory (transposition zone). The aim is to outline a methodology to transform depth intervals into geological time intervals and thus to quantify precisely the sedimentation rate variation, estimate duration; for example the duration of bio-stratigraphical units or of hiatuses. The latter point is particularly important because a continuous time recording is often assumed in geological modelling. The spatial variations can be studied on various scales. First, well-to-well correlations are established between seven wells at different scales. Relative variations of the thickness are observed locally. Second, FMI (Full-bore Formation Micro-Imager, Schlumberger) data are studied in detail to extract as much information as possible. For example, the analysis of FMI images reveals a clear carbonate - clay inter-bedding which displays cycles. Third, geostatistical tools are used to study these cycles. The vario-graphic analysis of conventional log data shows one metre cycles. With FMI data, smaller periods can be detected. Variogram modelling and factorial kriging analysis suggest that three spatial periods exist. They vary vertically and laterally in the boreholes but cycle ratios are stable and similar to orbital-cycle ratios (Milankovitch cycles). The three periods correspond to eccentricity, obliquity and precession. Since the duration of these orbital cycles is known, depth intervals can

  7. Definition of an equilibration protocol for batch experiments on Callovo-Oxfordian argillite

    Science.gov (United States)

    Descostes, M.; Tevissen, E.

    In order to elude difficulties concerning reproducing controlled conditions and avoiding chemical perturbation from sampling to laboratory experiments, an equilibration protocol of crushed Callovo-Oxfordian argillite in contact with synthetic pore water is proposed. It consists of a rinse-cycle with chosen synthetic waters. Hence, artifacts such as porosity variability, secondary paragenesis of evaporitic feature and a consecutive changing of water chemistry may be corrected. Equilibrium conditions are defined when both rinsing and leaching solutions are identical. In the first phase of this work, an input grid concerning reaction duration, number of rinsing and water/rock ratio associated to a specify methodology (anoxic and P CO 2 controlled atmosphere glove box) are given. We propose a water/rock ratio equal to 5, a first 72 h rinse followed by three others of 24 h. The protocol was tested among nine synthetic waters and validated regarding major aqueous elements. A geochemical modelling allowed us to identify the reactional mechanisms occurring during the whole procedure in terms of (1) modelling reactions taking place during the various rinses; (2) quantification of the dissolution/precipitation reactions and (3) modelling the condition of the sample. According to the rinsing water composition and P CO 2, dissolution of carbonate minerals may occur and is accompanied by a redistribution of sorbed species at argillaceous mineral surface. Solution analysis coupled with geochemical modelling show an increasing of aqueous K +, consequent upon cationic exchange reactions K +/Na +. Besides, the dissolution of carbonate minerals produced Ca 2+ and Mg 2+ which in turn are exchanged with K + and H +. Silica is controlled by the solubility of chalcedony. However, pH seems to be hardly imposed from the rinsing solution, since it is principally buffered by calco-magnesio-carbonate system. Moreover, anoxic conditions are not sufficient to restore natural reducing

  8. Radiation sensitivity of natural organic matter: Clay mineral association effects in the Callovo-Oxfordian argillite

    International Nuclear Information System (INIS)

    Clay-rich low-organic carbon formations (e.g., Callovo-Oxfordian argillite in France and Opalinus Clay in Switzerland) are considered as host rocks for radioactive waste disposal. The clay-organic carbon has a strong impact on the chemical stability of the clays. For this reason, the nature of the clay-organic carbon, the release of hydrophilic organic compounds, namely, humic (HA) and fulvic acids (FA) and the radiation sensitivity of the undisturbed host rock organics was investigated. The clay sample originates from Oxfordian argillite (447 m depth, borehole EST 104). HA and FA were extracted following the standard International Humic Substance Society (IHSS) isolation procedure. Synchrotron based (C-, K-, Ca-, O- and Fe-edge XANES) scanning transmission X-ray microscopy (STXM) and FT-IR microspectroscopy was used to identify under high spatial resolution the distribution of clay-organic matter with different functionality using principal component and cluster analysis. The results show that in this old (Jurassic) geological formation, small parts of the organic inventory (1-5%) keeps the structure/functionality and can be mobilized as hydrophilic humic substance type material (HA and FA). Target spectra analysis shows best correlation for isolated humic acids with organics found in smectite-rich regions, whereas the extractable FA has better spectral similarities with the illite mixed layer minerals (MLM) regions. After radiation of 1.7 GGy under helium atmosphere the same rock sample area was investigated for radiation damage. Radiation damage in the smectite and illite-MLM associated organic matter is comparably low with 20-30% total oxygen mass loss and 13-18% total carbon mass loss. A critical dose dc of 2.5 GGy and a optical density after infinite radiation (OD∝) of 54% was calculated under room temperature conditions. C(1s) XANES show a clear increase in C=C bonds especially in the illite-MLM associated organics. This results suggests a combination of

  9. Microbial investigations in Opalinus clay from Mont Terri and in Callovo-Oxfordian argillite from Meuse/Haute-Marne

    International Nuclear Information System (INIS)

    The subject of this Ph.D. thesis deals with research achieved in the context of the Axis 2 of the law Bataille voted on December 30, 1991 about the possibility of building a deep geological repository for medium or high activity and long living nuclear waste. Nearby such a site, some microorganisms may influence the mobility of radionuclides coming from the waste canisters. This work consisted in looking for autochthonous microorganisms in the Opalinus clay formation from Mont Terri (Switzerland) and in the Callovo-Oxfordian argillite from Meuse/Haute-Marne (France). Microbial Investigations in these unknown unperturbed environments suggested very low microbial densities in the clayey sediments. However, new bacterial species could be isolated from those samples. In addition, a part of the allochthonous population, which has been introduced by air and human activity, could be identified in the Meuse/Haute-Marne underground research laboratory. (author)

  10. Experimental study of thermo-hydro-mechanical behaviour of Callovo-Oxfordian Clay-stone

    International Nuclear Information System (INIS)

    During the different phases of the exothermic radioactive waste deep disposal (excavation, operation) and after permanent closure, the host rock is submitted to various coupled mechanical, hydraulic and thermal phenomena. Hence, a thorough investigation of the thermo-hydro-mechanical behaviour of the rock is necessary to complete existing data and to better understand and model the short and long term behaviour of the Callovo-Oxfordian (COx) clay formation in Bure (Meuse/Haute-Marne - M/HM), considered by ANDRA as a potential host rock in France.In this work, the compression - swelling behaviour of the COx Clay-stone was first investigated by carrying out a series of high-pressure oedometric tests. The results, interpreted in terms of coupling between damage and swelling, showed that the magnitude of swelling was linked to the density of the fissures created during compression. In a second step, the hydro-mechanical and thermo-hydro-mechanical behaviour of the saturated Clay-stone under a mean stress close to the in situ one were investigated by using two devices with short drainage path (10 mm), namely a isotropic cell and a newly designed hollow cylinder triaxial cell with local displacement measurements. These devices helped to solve two majors problems related to testing very low permeability materials: i) a satisfactory previous sample saturation (indicated by good Skempton values) and ii) satisfactory drainage conditions. Some typical constitutive parameters (Skempton and Biot's coefficients, drained and undrained compressibility coefficients) have been determined at ambient temperature through isotropic compression tests that also confirmed the transverse isotropy of the Clay-stone. The consistency of the obtained parameters has been checked in a saturated poro-elastic framework. Two aspects of the thermo-hydro-mechanical behaviour of the COx Clay-stone have then been investigated through different heating tests and through drained and undrained isotropic

  11. Numerical modelling of an in situ ventilation test in Callovo-Oxfordian clay-stone

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Nowadays, long-term management of radioactive waste is a major issue. The solution currently being considered is the repository in deep argillaceous geological media with low permeability. To study the feasibility of such repository, several underground research laboratories (URL) have been developed and in situ experiments are performed to characterise the host formation behaviour. The excavation process creates the so-called excavation damaged zone (EDZ) around the galleries composing underground structures. Within this zone mechanical and hydraulic properties are modified, for instance the hydraulic permeability is higher than in the rock formation. Such zone could alter the confining function of the formation then its behaviour is a crucial issue. The drainage and the ventilation in galleries may also influence the size and the structure of the EDZ therefore Andra performed a ventilation test (SDZ) in the Meuse/Haute-Marne URL (France) drilled in Callovo-Oxfordian clay-stone. The purpose is to characterise the influence of controlled ventilation imposed in an experimental gallery on the behaviour of the rock mass and the damaged zone. Numerical modelling is performed in order to calibrate the model and acquire a better understanding of transfers occurring during the test. A biphasic flow model is used to reproduce water and air transfers in partially saturated porous media. The exchanges between the cavity and the rock are modeled with a nonclassical boundary condition including water and vapour exchanges governed by a vapour mass transfer coefficient. The constitutive mechanical law used for the clayey rock is a linear elastic-perfectly plastic model with a Van Eekelen yield surface. The modelling takes into account the hydraulic permeability anisotropy and a damaged zone a priori defined. Firstly, only fluid transfer is modeled in 2D plane strain, 2D axisymmetric and 3D state models. Numerical results

  12. Coupled-processes in the Callovo-Oxfordian shales at the Bure site: implications for the transports of water and solutes

    International Nuclear Information System (INIS)

    This research thesis is related to the ANDRA's project of building a deep storage site for long-life, high- and medium-activity radioactive wastes within a Callovo-Oxfordian geological formation which is investigated by the Bure underground laboratory. As previous studies revealed hydrostatic loads greater than expected, the objective of this research is to explain these overpressures by validating or invalidating hypotheses on natural phenomena which could cause them. These hypotheses are: a progressive decrease of rock porosity in relationship with a continuous increase of mechanical stresses in the Callovo-Oxfordian, the existence in the past of hydrostatic pressures greater than now, and an osmotic effect. The author gives an overview of the knowledge about clays and their interactions with surrounding solutes, about coupled flows and overpressures. Based on petro-physical data, she proposes an assessment of the chemical osmotic coupling coefficient. Based on experimental and numerical investigations, she reports the measurement of this coefficient in the Callovo-Oxfordian argillites, and then proposes new interpretations of the measured overpressures

  13. Biological and geochemical processes involved during denitrification in Callovo-Oxfordian clay

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. The clay-rich Callovo-Oxfordian (COx) formation has been selected for the disposal of medium and high level, long-lived radioactive waste. After waste cell closure and degradation of package some intermediate-level waste will release nitrate. The latter is likely to diffuse into the surrounding environment (engineered barriers and geological host formation) and interact with a variety compounds present in the barrier components and the rocks. These interactions may result in modification of chemical conditions and impact storage conditions and radionuclide retention. Our work is focused on the understanding of the fate of nitrates released during and after degradation of waste package. We developed a coupled approach considering both geochemical and biological processes of nitrate reduction to simulate reactions occurring at the interface of the engineered barrier and the clay-rich COx formation. Laboratory experiments have been carried out in order to acquire data on kinetics of denitrification coupled with a molecular approach using enzymatic and metabolic activities as a tool for an accurate estimation of biomass. Denitrification has been monitored in a synthetic solution comparable to COx pore water supplemented with acetate and nitrate and amended with a heterotrophic denitrifying strain, Pseudomonas mandelii. Several conditions are applied considering different acetate/nitrate ratios in the presence or absence of COx clay. Before the beginning of experiments, the headspace is flushed with N2 gas to remove oxygen from flasks. Acetylene is used to stop denitrification reaction after the production of N2O gas and thus avoid the formation of N2 gas. Two successive redox reactions are thus expected to occur in experiments. Samples are regularly collected to analyze physical and chemical parameters as well as biological parameters. Biomass is estimated and monitored using both optical microscopy and quantitative

  14. Modelling the coupled chemico-osmotic and advective-diffusive transport of nitrate salts in the Callovo-Oxfordian clay

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Fine-grained saturated porous materials can act as a semi-permeable osmotic membrane when exposed to a solute concentration gradient. The ions diffusion is hindered while water movement towards higher concentrations takes place in the semi-permeable membrane. The capacity of the fine-grained porous material to act as a semi permeable osmotic membrane is referred to as the osmotic efficiency (its value is 1 when the membranes is ideal, less than 1 when the membrane is leaky, allowing diffusion). The efficiency to retain ions in solution is dependent on the thickness of the diffuse double layer which itself depends on the solution concentration in the membrane. Clay rich formations have been shown to act as non-ideal semi-permeable membrane. Andra is investigating the Callovo-Oxfordian clay as a host rock for intermediate-level to high-level radioactive waste. In this context, it has been feared that osmotic water flows generated by the release of sodium nitrate salt in high concentrations, out of intermediate radioactive bituminous waste, could induce important over-pressures. The latest would eventually lead to fracturing of the host rock around the waste disposal drifts. The purpose of the present study was to develop a simulation code with the capacity to assess the potential impact of osmosis on: the re-saturation of the waste disposal drifts, the pressure evolution and the solute transport in and around a waste disposal drift. A chemo-osmotic coupled flow and transport model was implemented using the FlexPDE-finite element library. Our model is based on the chemo-osmotic formulation developed by Bader and Kooi, 2005. The model has been extended to highly concentrated solutions based on Pitzer's equation. In order to assess the impact of osmotic flow on the re-saturation time, the model was also designed to allow unsaturated flow modelling. The model configuration consists of an initially unsaturated 2D

  15. Characterisation of iodide retention on Callovo-Oxfordian argilites by batch, column and through-diffusion experiments

    International Nuclear Information System (INIS)

    Full text of publication follows: Iodine-129 is commonly among the largest contributors to the calculated health risk associated with long-term nuclear underground waste disposal. Therefore, its behaviour in Callovo-Oxfordian argilites, the argillaceous host rock of the ANDRA Meuse/Haute-Marne underground laboratory, must be fully characterized. A weak and reversible sorption of iodide on surface clay and oxide minerals is often opposed to an irreversible retention on organic matter, more intense but kinetically slower. In the present study, several experimental methods (batch experiments, Stop and Flow columns and through-diffusion cells) have been implemented to study and quantify iodide ion retention, using 125I- as radiotracer. Several argillite cores were studied, coming from different back-holes (EST205 and EST312/322). All the experiments were performed with a synthetic solution, as close as possible of the natural pore water. Thiosulfates were systematically added to the synthetic solution in order to ensure the predominance of iodide. Sorption/desorption on batch tubes and column experiments have firstly been conducted to investigate the nature of iodine retention on argilites. Irreversible sorption of iodide was demonstrated with both methods, when long contact duration was provided. On the contrary, no reversible sorption of iodide was detected. Nevertheless, rock oxidation, conversion to iodates, may be encountered with these long-time experiments. Hence, through-diffusion cells were carried out in order to get closer to in situ physico-chemical conditions. Moreover, these experiments allow to work directly on centimetric rock samples (without crushing). During preparation and equilibration, careful attention was brought to maintain a permanent anoxic atmosphere (operations in an anhydrous and anoxic glovebox). All sampling were also made under a CO2/N2 flux. Influence of total iodine concentration (2.10-7 to 10-3 mol.L-1) was studied, comparing 125I

  16. How mobile is iodide in the Callovo-Oxfordian claystones under experimental conditions close to the in situ ones?

    International Nuclear Information System (INIS)

    The iodide behaviour towards the Callovo-Oxfordian claystone was studied using batch and diffusion experiments under conditions which limited the artefacts cited in the literature to be responsible for the iodide uptake (i.e. the experiments were carried out under anoxic conditions with N2/CO2 atmosphere with a monitoring of the iodine redox-state). The results show that all the radioactive iodine was 125I-, with no measurable activity for 125IO3- which is known to have a higher affinity for the rock than iodide. Moreover, the batch experiments revealed no sorption, independently of the initial iodide concentration (from 10-6 to 10-3 mol L-1) and the contact time (up to 106 days). Conversely, the diffusion experiments indicated a weak but measurable retention. The through-diffusion experiments led to distribution ratio values only significant (R-D similar to 0.05 mL g-1) for initial iodide concentration ≤ 10-4 mol L-1. Higher R-D values were estimated from out-diffusion experiments, ranging from about 0.05 mL g-1 for an initial concentration of 10-3 mol L-1 to 0.14 mL g-1 for the lowest one. A retention phenomenon that could be reversible and kinetically-controlled was proposed to explain the differences in the extent of the iodide retardation of the two types of diffusion experiments. (authors)

  17. Convergence in anisotropic conditions: gallery behaviour in the Callovo-Oxfordian clayey layer in North-Eastern France

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Coyne et Bellier (Tractebel Engineering) has been supplying geotechnical services to Andra since 1994 regarding the feasibility for developing a repository for radioactive waste in a 490 m deep clayey formation at the Meuse/Haute-Marne site. Armines/Mines-ParisTech (French engineering school) has been an Andra scientific partner for several years due to its expertise in rock creep behaviour as well as in mining technologies. Throughout the different works carried out for Andra (especially the studies concerning the enlargement of the underground research laboratory), the behaviour of the Callovo-Oxfordian clayey were computed. These studies are used mainly for predicting the long-term behaviour of this layer. Lemaitre's rheological law (or modified Norton's law) has been used for such purposes. This time-dependent law is able to model the isotropic hardening of an elastic-viscoplastic solid by taking into account a non linear viscosity (γ) which Coyne et Bellier has decided to represent by means of a cone-shaped dash-pot element (stiffness increases during creep, cf. Eric Boidy's PhD). This hypothesis, together with that standing for 'long-term incompressibility' (viscoplastic deformation occurs at constant volume), allows the law be expressed by means of the second invariants of the stress (q) and strain (εvp) tensors. The rheological model when the long term behaviour takes place beyond a stress threshold (σS) is shown. Modelling works that use this law reproduce well convergence measurements as long as radial stresses around the galleries are isotropic. When the stress field around the gallery is anisotropic, the classic Lemaitre's law no longer fits the convergence measurements. This is the case for the GMR gallery at the main level of the laboratory: the horizontal stress is 1.3 times greater than the vertical stress whilst the average vertical convergence is more than five

  18. Impact of landscape evolution over 1 million years on the hydraulic boundary conditions of the Callovo-Oxfordian layer

    Energy Technology Data Exchange (ETDEWEB)

    Teles, V.; Mouche, E.; Maugis, P.; Huhle, M. [Laboratoire des Sciences du Climat et de l' Environnement (UMR CEA-CNRS), Orme des Merisiers, 91 - Gif sur Yvette (France); Brulhetz, J.; Vigneron, G.; Wendlingz, J. [Agence Nationale pour la Gestion des Dechets Radioactifs (ANDRA), 92 - Chatenay Malabry (France)

    2005-07-01

    The geomorphologic evolution in the Eastern part of the Paris Basin has been important during the last three hundred thousand years. The landscape evolution has been characterized mainly by outcrop retreat linked to valley incisions. The outcropping limestones have been affected by karst development. The hydrographic network has evolved through a stepped process due to river piracies. In the Meuse/Haute Marne region, the Meuse River tributaries have been captured progressively by rivers of the Seine basin. Specifically, on the Bure area, the Saulx and Ornain Rivers became tributaries of the Marne River since circa 200 ky B.P. Based on mapping and dating results, Andra has quantified the geomorphological evolution of the Meuse/Haute-Marne site for several hundred thousand years in the past and has estimated the future evolution over 1 million years. The Callovo-Oxfordian boundary conditions depend on the hydraulic heads in the two surrounding aquifers, the Oxfordian limestone on top and the Dogger one below. Both aquifer outcrops are modified over the next million years. For the present study, the geomorphologic evolution is considered independently of other processes and translated in the hydrogeological model in terms of changes in the hydraulic boundary conditions at the surface. The hydrodynamic simulations have been performed with the code CASTEM2000 (implemented by CEA (Atomic Energy Commissariat)) using a mixed hybrid finite-element formulation. For these groundwater flow simulations, three modelled stages are presented: the present, 500,000 years (500 Ky) and 10{sup 6} years (I Ma) in the future. The landscape evolution is merely considered through the use of three different topographies on which the boundary conditions are applied. According to Andra predictions, at the Meuse/Haute-Marne site, the valley incisions on the Bure plateau will locally reach the Oxfordian limestone. Thus, the Oxfordian aquifer exhibits more changes due to topographic evolution

  19. Diffusion Experiments with Opalinus and Callovo-Oxfordian Clays: Laboratory, Large-Scale Experiments and Microscale Analysis by RBS

    International Nuclear Information System (INIS)

    Consolidated clays are potential host rocks for deep geological repositories for high-level radioactive waste. Diffusion is the main transport process for radionuclides (RN) in these clays. Radionuclide (RN) diffusion coefficients are the most important parameters for Performance Assessment (PA) calculations of clay barriers. Different diffusion methodologies were applied at a laboratory scale to analyse the diffusion behaviour of a wide range of RN. Main aims were to understand the transport properties of different RNs in two different clays and to contribute with feasible methodologies to improve in-situ diffusion experiments, using samples of larger scale. Classical laboratory essays and a novel experimental set-up for large-scale diffusion experiments were performed, together to a novel application of the nuclear ion beam technique Rutherford Backscattering Spectrometry (RBS), for diffusion analyses at the micrometer scale. The main experimental and theoretical characteristics of the different methodologies, and their advantages and limitations are here discussed. Experiments were performed with the Opalinus and the Callovo-Oxfordian clays. Both clays are studied as potential host rock for a repository. Effective diffusion coefficients ranged between 1.10-10 to 1.10-12 m2/s for neutral, low sorbing cations (as Na and Sr) and anions. Apparent diffusion coefficients for strongly sorbing elements, as Cs and Co, are in the order of 1.10-13 m2/s; europium present the lowest diffusion coefficient (5.10-15 m2/s). The results obtained by the different approaches gave a comprehensive database of diffusion coefficients for RN with different transport behaviour within both clays. (Author) 42 refs

  20. Relative humidity in the ventilation air of the storage tunnels dug in the Callovo-Oxfordian argilites

    International Nuclear Information System (INIS)

    Exploitation of a deep underground repository implies a ventilation of all tunnels and shafts in order to maintain good working conditions. Based on actually planned repository architecture, the ventilation machinery is dimensioned to produce around 1 000 000 m3 of moving air per second, which will implies an air velocity of several meters per second in the tunnels and shafts. The air used for the ventilation is picked at ground level around the site without any pretreatment. This air has a relative humidity and a temperature varying throughout the year, on a monthly basis, from 84 % and 3 C in winter to 75% and 17 in summer. What ever part of the year considered, the ventilation air entering the ventilation shaft is not saturated in water vapor. The annual mean of relative humidity is around 80% for a annual temperature of around 10 C. Moving into the shafts and tunnel system, the ventilation air will gain, or loose, some water, and also exchange heat with the surrounding rock. These mass and energy exchange will modify the temperature and relative humidity of the air. As hydraulic boundary condition of the rock on the tunnel walls is conditioned by the relative humidity of the ventilation air, knowing the evolution of this variable along the shafts and galleries, will help determine the hydraulic impact of the storage exploitation on the argilites of the Callovo-Oxfordian. A relative humidity less than 100% implies a desaturation of the rock around the tunnel walls, and even a slit decrease in relative humidity will generate quite high suctions on the tunnel walls. A numerical 2D axisymmetric model taking into account air flow and heat and mass exchange between air and rock was build by TEC INGENIERIE to estimate the relative humidity along the tunnels, from the surface to the repository zones. (authors)

  1. Characteristic properties and CM(3) complexation of humic and fulvic acids from callovo-oxfordian and opalinus clay

    International Nuclear Information System (INIS)

    Clay is foreseen both as back-fill material and host rock for nuclear waste disposal. It contains organic matter that can be released and form dissolved organic matter (DOC). Part of this DOC consists of humic and fulvic acids. Humic substances in natural water are present in the form of humic colloids, consisting of the organic entities, associated mineral structures and complexed metal ions. These humic colloids can play a major role in the radionuclide migration in natural aquifer systems. Cement may be present in a nuclear waste repository as a waste form or as part of engineered structures. In case of water intrusion, cement dissolution will, amongst others, lead to high pH values (initial pH>13). On a short time scale, a minor fraction (few percent) of the clay organic matter is dissolved. With prolonged contact time with alkaline solution, the hydrophobic clay organic matter becomes chemically converted and a large portion (up to around 50% after about 1.5 years) is forming hydrophilic humic and fulvic acids. In this paper, humic and fulvic acids initially released from Callovo-Oxfordian and Opalinus Clay under near-field high pH conditions are quantified and characterised. Furthermore, their complexation with Cm3+ is investigated. The humic and fulvic acids are characterised by asymmetrical flow field-flow fractionation (AFFFF) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The latter technique can offer practically the same level of information as nuclear magnetic resonance (NMR) but require very low amount of samples (∼ 10-3 mg). The complexation with the Cm3+ ion is studied by time resolved laser fluorescence spectroscopy (TRFLS). It is shown that humic and fulvic acids may result in enhanced radionuclide migration in clay under cement dissolution conditions. (authors)

  2. Impact of landscape evolution over 1 million years on the hydraulic boundary conditions of the Callovo-Oxfordian layer

    International Nuclear Information System (INIS)

    The geomorphologic evolution in the Eastern part of the Paris Basin has been important during the last three hundred thousand years. The landscape evolution has been characterized mainly by outcrop retreat linked to valley incisions. The outcropping limestones have been affected by karst development. The hydrographic network has evolved through a stepped process due to river piracies. In the Meuse/Haute Marne region, the Meuse River tributaries have been captured progressively by rivers of the Seine basin. Specifically, on the Bure area, the Saulx and Ornain Rivers became tributaries of the Marne River since circa 200 ky B.P. Based on mapping and dating results, Andra has quantified the geomorphological evolution of the Meuse/Haute-Marne site for several hundred thousand years in the past and has estimated the future evolution over 1 million years. The Callovo-Oxfordian boundary conditions depend on the hydraulic heads in the two surrounding aquifers, the Oxfordian limestone on top and the Dogger one below. Both aquifer outcrops are modified over the next million years. For the present study, the geomorphologic evolution is considered independently of other processes and translated in the hydrogeological model in terms of changes in the hydraulic boundary conditions at the surface. The hydrodynamic simulations have been performed with the code CASTEM2000 (implemented by CEA (Atomic Energy Commissariat)) using a mixed hybrid finite-element formulation. For these groundwater flow simulations, three modelled stages are presented: the present, 500,000 years (500 Ky) and 106 years (I Ma) in the future. The landscape evolution is merely considered through the use of three different topographies on which the boundary conditions are applied. According to Andra predictions, at the Meuse/Haute-Marne site, the valley incisions on the Bure plateau will locally reach the Oxfordian limestone. Thus, the Oxfordian aquifer exhibits more changes due to topographic evolution than the

  3. Diffusion Experiments with Opalinus and Callovo-Oxfordian Clays: Laboratory, Large-Scale Experiments and Microscale Analysis by RBS

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Gutierrez, M.; Alonso, U.; Missana, T.; Cormenzana, J.L.; Mingarro, M.; Morejon, J.; Gil, P.

    2009-09-25

    Consolidated clays are potential host rocks for deep geological repositories for high-level radioactive waste. Diffusion is the main transport process for radionuclides (RN) in these clays. Radionuclide (RN) diffusion coefficients are the most important parameters for Performance Assessment (PA) calculations of clay barriers. Different diffusion methodologies were applied at a laboratory scale to analyse the diffusion behaviour of a wide range of RN. Main aims were to understand the transport properties of different RNs in two different clays and to contribute with feasible methodologies to improve in-situ diffusion experiments, using samples of larger scale. Classical laboratory essays and a novel experimental set-up for large-scale diffusion experiments were performed, together to a novel application of the nuclear ion beam technique Rutherford Backscattering Spectrometry (RBS), for diffusion analyses at the micrometer scale. The main experimental and theoretical characteristics of the different methodologies, and their advantages and limitations are here discussed. Experiments were performed with the Opalinus and the Callovo-Oxfordian clays. Both clays are studied as potential host rock for a repository. Effective diffusion coefficients ranged between 1.10{sup -}10 to 1.10{sup -}12 m{sup 2}/s for neutral, low sorbing cations (as Na and Sr) and anions. Apparent diffusion coefficients for strongly sorbing elements, as Cs and Co, are in the order of 1.10-13 m{sup 2}/s; europium present the lowest diffusion coefficient (5.10{sup -}15 m{sup 2}/s). The results obtained by the different approaches gave a comprehensive database of diffusion coefficients for RN with different transport behaviour within both clays. (Author) 42 refs.

  4. On the Thermo-Hydro-Mechanical Behaviour of a Sheared Callovo-Oxfordian Claystone Sample with Respect to the EDZ Behaviour

    Science.gov (United States)

    Menaceur, Hamza; Delage, Pierre; Tang, Anh Minh; Conil, Nathalie

    2016-05-01

    To better understand the impact of temperature elevation on the response of the excavation damaged zone around repository cells and galleries for radioactive waste disposal, the combined effects of shear and temperature elevation were investigated in the laboratory on the Callovo-Oxfordian claystone. To do so, a hollow cylinder thermal triaxial cell with short drainage path specifically developed for low permeability rocks was used. Once properly saturated under stress conditions close to in situ, the specimen was sheared along a constant effective mean stress path mimicking the stress path followed during gallery excavation. The shear stress was afterwards released and an undrained heating test was performed on the sheared specimen. It was observed that the temperature increase under undrained conditions led to a thermal increase in pore water pressure resulting in a decrease in mean effective stress that brought back the sheared specimen to failure, evidencing a thermally induced failure. Steady state radial permeability tests performed at various stages of the test demonstrated that the overall permeability of the sheared specimen was comparable to that before shearing, confirming the excellent self-sealing properties of the Callovo-Oxfordian claystone. This shows that, in spite of being possibly remobilised by temperature elevation, the EDZ will keep an overall permeability constant equal to that of the massive rock, keeping the same isolation properties.

  5. Fe(0)-clays interactions at 90°C under anoxic conditions: a comparative study between clay fraction of Callovo-Oxfordian and other purified clays

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. In the context of the geological disposal of high-level radioactive waste it is of prime importance to understand the interactions between the saturated clay formation and steel containers. This can be achieved through an in-depth analysis of iron-clay interactions. Previous studies on the subject investigated the influence of solid/liquid ratio, iron/clay ratio, temperature and reaction time. The aim of the present study is to explain Callovo-Oxfordian-Fe(0) interactions by determining the role of each mineral phases present in the Callovo-Oxfordian (clay minerals, quartz, carbonates and pyrite) on the mechanisms of interaction between metal iron and clay particles. In that context, it is especially important to understand in detail the influence of clay nature and to obtain some insight about the relationships between interaction mechanisms at the molecular scale and crystallographic properties (particle size, TO or TOT layers, amount of edge faces...). The influence of the combination of different clays and the addition of other minerals must also be studied. In a first step, the Callovo-Oxfordian argillite from the Andra's underground research laboratory was purified to extract the clay fraction (illite, illite-smectite, kaolinite and chlorite). Batch experiments were carried out in anoxic conditions at 90 deg. C in the presence of background electrolyte (NaCl 0.02 M.L-1, CaCl2 0.04 M.L-1) for durations of one, three or nine months in the presence of metallic iron powder. Experiments without iron were used as control. The iron/clay ratio was fixed at 1/3 with a solid/liquid ratio of 1/20. The above mentioned experiments were also carried out in parallel on other purified clays: two smectites (Georgia bentonite and SWy2 from the Clay Minerals Society), one illite (illite du Puy) and one kaolinite (KGa2, from the Clay Minerals society). At the end of the experiments, solid and liquid phases were separated by

  6. Determination of hydraulic properties of the Callovo-Oxfordian argillite at the bure site: Synthesis of the results obtained in deep boreholes using several in situ investigation techniques

    Science.gov (United States)

    Distinguin, Marc; Lavanchy, Jean-Marc

    Since 1991, ANDRA ( Agence Nationale pour la gestion des Déchets Radioactifs - National Radioactive Waste Management Agency) has been performing research on the possibility of geologic disposal of high level radioactive waste. In 1999, Andra began constructing an Underground Research Laboratory at Bure, a site located on the border of the Meuse-Haute-Marne departments, 300 km East of Paris. The laboratory is investigating the Callovo-Oxfordian argillite, a 130 m thick middle Jurassic stratum, at a depth of about 420 m. Argillite is a clay-rich sedimentary rock with low-permeability. Between 1994 and 2004, Andra collected from deep boreholes an impressive wealth of data covering a wide range of geosciences. This paper focuses on the hydraulic data related to argillite, including the results from short-term hydraulic packer tests and long-term monitoring of the formation pressures. Three types of tools are used on the site for investigations in deep boreholes. The first one is a conventional packer test tool used in the petroleum industry and adapted for hydrogeological purposes. The main objective is to determinate the permeability of the formation through short-term tests (24-72 h) at about 10 regular intervals. The two other types of tool are permanent monitoring devices. The electromagnetic pressure gauge (EPG) is totally isolated from the surface perturbations. There are no electric or hydraulic lines to the surface and the borehole is cemented. The advantage of this tool is that the formation almost recovers its initial pressure, avoiding disturbances from surface. Although the multi-packer equipment, installed in an open borehole can be affected by surface perturbations, it is used to measure pressure at different isolated levels in the same borehole ( i. e., 11 chambers in one borehole). Evaluations of the formation pressure (freshwater head) and hydraulic conductivity have been performed for all intervals investigated (19 short-term packer tests and 15 long

  7. Chemical and isotopic analysis of hydrocarbon traces degassed out of Callovo-Oxfordian argilites from Bure (France): methodology and results

    International Nuclear Information System (INIS)

    Isotopic mass spectrometry online with gas chromatography (GC-C-IRMS) allows the measurement of the carbon isotopic ratios of hydrocarbon gases (C1 to C4) after complete combustion to CO2. The method also permits to measure proportions of the different hydrocarbon gases and CO2. Such data provide valuable information about the source and genesis of a gas sample, as well as the post-formation physicochemical processes which might affect it in the geological environment. In particular, it is possible to distinguish hydrocarbon gases of bacterial or thermogenic origin based on the proportion of methane and the carbon isotope ratio as measured by GC-C-IRMS. However, if the relative concentrations of carbon molecules are very small (from 1 ppm to 1000 ppm), the isotopic information cannot be obtained directly with GC-C-IRMS. An additional step allowing the pre-concentration of hydrocarbons must be introduced in the analytical procedure. Indeed, in order to obtain an adequate accuracy, several operating conditions are of prime importance: sufficient signal intensity, good quality peak shape, low signal/noise ratio. We present here a pre-concentration system based on the removal of major gas compounds (N2, O2, Ar, etc...) and trapping of carbon molecules. The purified carbon molecules are released in an inert carrier gas, focussed through a tiny capillary, and introduced in the chromatograph for separation, combustion of each compound and final analysis in the mass spectrometer. This technique provides the chemical concentration in the initial gas and the carbon isotope composition of each individual carbon molecular compound. Its high sensitivity allows measurement of isotopic ratios for concentrations as low as 1 ppm of methane, 0,5 ppm of ethane and 0,3 ppm of propane, for bulk gas samples of 10 cc in standard conditions. Total analytical uncertainty on δ13C measurements is ± 1 0/00 or better. The results of a first application of this technique to the Callovo-Oxfordian

  8. Method development for evaluating the redox state of Callovo-Oxfordian clayrock and synthetic montmorillonite for nuclear waste management

    International Nuclear Information System (INIS)

    Highlights: • Three reduction methods were studied with 57Fe Mössbauer spectrometry on Fe-clays. • Reduction with H2(g) in dried condition shows intermediate hyperfine parameters. • A complex mechanism occurs for structural Fe(III) reduction in this condition. • H2(g) is a powerful reductive reagent as sodium dithionite in our study. • The clayrock redox and confinement properties will only be slightly affected by hydrogen gas. - Abstract: Understanding the redox characteristic of the host geological layer is vital for radioactive waste management. In order to predict the radionuclides behavior during their release it must be thoroughly evaluated. This redox property could be affected by hydrogen gas which arises from the anaerobic corrosion of the stainless steel container. In this study, reduction methods using hydrogen gas or sodium dithionite as a reductive agent were tested on reference synthetic montmorillonites with various Fe(III) contents. The reduced samples were systematically studied with 57Fe transmission Mössbauer spectrometry. After reduction with H2(g) in dry conditions, the Mössbauer spectra are characterized by hyperfine parameters located between those for Fe(III) and Fe(II), compared to reduction in water suspension with Na2S2O4(aq) and H2(g) which gives standard Fe(II) hyperfine parameters. The former results with dry H2(g) highlight an incomplete reduction and the possibility to have a Fe(III)–Fe(II) system with one-electron sharing. A natural clayrock sample, the Callovo-Oxfordian (COx), was also considered. The results above allowed its reduction to be evaluated. Much attention has also been focused on the modeling of the hyperfine spectra because of COx structure complexity. In addition, a hyperfine parameter data base was developed for a variety of Fe components based on an extensive literature review. This database provides additional statistical order to the study. This study highlights also that Mössbauer spectrometry

  9. Effect of Callovo-Oxfordian clay rock on the dissolution rate of the SON68 simulated nuclear waste glass

    Energy Technology Data Exchange (ETDEWEB)

    Neeway, James J., E-mail: James.Neeway@pnnl.gov [SUBATECH, Unité Mixte de Recherche 6457, École des Mines de Nantes, CNRS/IN2P3, Université de Nantes, BP 20722, 44307 Nantes cedex 3 (France); Abdelouas, Abdesselam; Ribet, Solange; El Mendili, Yassine [SUBATECH, Unité Mixte de Recherche 6457, École des Mines de Nantes, CNRS/IN2P3, Université de Nantes, BP 20722, 44307 Nantes cedex 3 (France); Schumacher, Stéphan [ANDRA, Parc de la Croix Blanche, 1/7 rue Jean Monnet, 92298 Châtenay-Malabry (France); Grambow, Bernd [SUBATECH, Unité Mixte de Recherche 6457, École des Mines de Nantes, CNRS/IN2P3, Université de Nantes, BP 20722, 44307 Nantes cedex 3 (France)

    2015-04-15

    Long-term storage of high-level nuclear waste glass in France is expected to occur in an engineered barrier system (EBS) located in a subsurface Callovo-Oxfordian (COx) clay rock formation in the Paris Basin in northeastern France. Understanding the behavior of glass dissolution in the complex system is critical to be able to reliably model the performance of the glass in this complex environment. To simulate this multi-barrier repository scenario in the laboratory, several tests have been performed to measure glass dissolution rates of the simulated high-level nuclear waste glass, SON68, in the presence of COx claystone at 90 °C. Experiments utilized a High-Performance Liquid Chromatography (HPLC) pump to pass simulated Bure site COx pore water through a reaction cell containing SON68 placed between two COx claystone cores for durations up to 200 days. Silicon concentrations at the outlet were similar in all experiments, even the blank experiment with only the COx claystone (∼4 mg/L at 25 °C and ∼15 mg/L at 90 °C). The steady-state pH of the effluent, measured at room temperature, was roughly 7.1 for the blank and 7.3–7.6 for the glass-containing experiments demonstrating the pH buffering capacity of the COx claystone. Dissolution rates for SON68 in the presence of the claystone were elevated compared to those obtained from flow-through experiments conducted with SON68 without claystone in silica-saturated solutions at the same temperature and similar pH values. Additionally, through surface examination of the monoliths, the side of the monolith in direct contact with the claystone was seen to have a corrosion thickness 2.5× greater than the side in contact with the bulk glass powder. Results from one experiment containing {sup 32}Si-doped SON68 also suggest that the movement of Si through the claystone is controlled by a chemically coupled transport with a Si retention factor, K{sub d}, of 900 mL/g.

  10. Impact of the solution ionic strength on strontium diffusion through the Callovo-Oxfordian clayrocks: An experimental and modeling study

    International Nuclear Information System (INIS)

    Highlights: • HTO and 85Sr diffusion is studied in clayrocks under increasing ionic strengths. • Sr diffusive flux is 5 times higher than HTO under standard porewater ionic strength. • Sr diffusive flux is reduced when the porewater ionic strength increases. • The Sr diffusive evolution is qualitatively reproduced by a surface diffusion model. - Abstract: Diffusion of cations in clayrocks is widely investigated, because deep clay-rich formations are currently considered as one of the potential host rocks for radioactive waste repositories. However, several authors have already reported that sorbing cations seem to diffuse at rates larger than those predicted by a simple pore diffusion model from their sorption coefficients and from the diffusive flux of non-sorbing water tracers. This process has been attributed to the migration of cations within the electrical double layer, next to the mineral surfaces, called the surface diffusion phenomenon. The aim of this work was to verify whether this “enhanced” cation diffusion compared to neutral species was observed for strontium and, if so, to what extent this effect might vary with the salinity of the synthetic solutions. These questions were addressed by performing batch sorption, through-diffusion and out-diffusion experiments on rock samples from the Callovo-Oxfordian claystone formation (France). The results showed that there was a good agreement of the distribution ratios (RD) determined on crushed and intact rocks by batch and through-diffusion methods with a RD decrease related to the increase of the sodium concentration, a sorption competitor. Such a trend was also well reproduced by means of a geochemical modeling based on the multi-site ion exchange (MSIE) theory. Moreover, the “enhanced” diffusion for strontium was clearly observed in this study: the Sr diffusive flux was almost five times higher than that for HTO in the cell with the lowest ionic strength, and diminished to less than 1

  11. Experimental observations of mechanical dilation at the onset of gas flow in Callovo-Oxfordian clay-stone

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Understanding the mechanisms controlling the advective movement of gas and its potential impact on the repository and host rock is important to both performance assessment and the long-term prediction of the repositories evolution. In a clay-based geological disposal facility (GDF), four primary phenomenological models can be defined to describe gas flow: (i) gas movement by diffusion and/or solution within interstitial fluids along prevailing hydraulic gradients; (ii) gas flow in the original porosity of the fabric, commonly referred to visco-capillary flow; (iii) gas flow along localised dilatant pathways (micro-fissuring) which may or may not interact with the continuum stress field; and (iv) gas fracturing of the rock similar to that performed during hydrocarbon stimulation exercises. To investigate which mechanism(s) control the advective movement of gas, two independent experimental studies on Callovo-Oxfordian clay-stone (COx) have been undertaken at the British Geological Survey (BGS) and Laego-Ensg Nancy. A bespoke triaxial apparatus, christened the stress path permeameter (SPP), was designed and constructed at the BGS. The SPP was specifically manufactured to be able to resolve very small volumetric (axial and radial) strains potentially associated with the onset of gas flow. To this end, three pressure-balanced dash-pots were located around the mid-plane of the sample, providing a continuous record of subtle variations in sample diameter during testing. Axial strain was recorded using a digital micrometer. Experiments were performed on preserved test material with a start saturation of 96%. At the start of testing the sample was loaded to the in situ conditions at Bure with a confining pressure of 12.5 MPa, axial stress of 13 MPa and a pore pressure of 4.5 MPa. The initial stage of testing was designed to re-saturate the sample fully and lasted 47 days. The sample exhibited a negative volumetric strain

  12. Coupled transport phenomena in a clay from a Callovo-Oxfordian formation; Phenomenes de transport couples dans les argiles du Callovo-Oxfordien

    Energy Technology Data Exchange (ETDEWEB)

    Paszkuta, M

    2005-06-15

    Low permeability materials containing clay play an important role in practical life and natural environment. Indeed, the ability of clay soils to act as semi permeable membranes, that inhibit the passage of electrolytes, is of great interest. The major objective of this thesis is to evaluate the transport properties of natural clays and in particular coupled transports when a pressure gradient, an electrical field, a concentration gradient and a temperature gradient interact. The material is a compact argillite extracted in East France from a Callovo-Oxfordian formation which was supplied to us by ANDRA. NaCl was used as the main solute. Two series of experiments were performed to measure permeability, diffusion, conductivity, the electro-osmotic coefficient and the Soret coefficient. (author)

  13. Spatial distributions of porosity, mineralogy and solute diffusion properties in the Callovo-Oxfordian rock formation (Meuse/ Haute Marne, France) and their relationships

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Pore space geometry and mineralogy are well known to control transfer properties of rocks. Quantification of porosity and mineral content at large scales (m-km) is thus an important issue to understand and estimate the transfer properties variability in the clay rock formation. In the context of CIGEO project, the 130 m thick Callovo-Oxfordian clay-rock formation has been thoroughly studied on a 250 km2 area located north from the Underground Research Laboratory (URL) of Bure. In addition to the URL, several boreholes have been drilled in this area during the last fifteen years, thus providing many core samples and several wire-line logs. Our goal is to analyze this wide set of data. At the rock formation scale, wire-line logging tools allow in-situ petrophysical characterizations of rocks with a high spatial resolution (30 - 15 cm). Two tools are specifically useful for our purpose: - Gamma-ray emission logging (total amount and spectrometer) which provides data on clay content and its spatial variability, - Nuclear Magnetic Resonance logging (the NMR tool provided by Schlumberger) which determines both total porosity and pore size distribution. On the other hand, core samples were extracted every 1 - 3 m and were submitted to pore space geometry (water content, mercury intrusion, density, specific surface area) and mineral characterizations (chemical analysis, XRD, cation exchange capacity) as well as diffusion experiments (tritiated water and chlorine) and retention tests (only for cesium), performed on a smaller set of samples. Using this data set, we performed statistical analysis within each geological unit in order to: - Evaluate the coherence and the relationships between the data obtained from core samples and wire-line logging tools measurements. This analysis asses the relationship between gamma-ray emission measured in each borehole and the clay mineral content; - Determine the lateral and vertical

  14. Influence of non-clay minerals on the interaction between metallic iron and Callovo-Oxfordian clay fraction

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. In the context of the geological disposal of high-level radioactive waste, it is of prime importance to understand the interaction mechanisms between the geological matrix, Callovo-Oxfordian clay rock (COx) and metallic iron, from the package overpack. In order to evidence the individual role of each clay component entering in the mineralogy of the COx, interactions between metallic iron and pure clays (smectites, illite and kaolinite) were first conducted. To investigate the role of the other minerals, the reactivity of COx, COx clay fraction (COxCF) and mixtures between COxCF and quartz, calcite or pyrite, was studied. Clays and additional minerals were put in contact with powder metallic iron with a weight ratio iron:clay fixed at 1:3 and a clay:solution ratio of 1:20. Proportions of non-clay minerals were deduced from the average COx composition: 50% clays, 24.5% quartz, 24.5% calcite and 1% pyrite. Batch experiments were carried out in anoxic conditions at 90 deg. C in the presence of background electrolyte (NaCl 0.02 M.L-1, CaCl2 0.04 M.L-1) in Parr reactors for durations of one, three or nine months. After reaction, solid and liquid phases were separated by centrifugation and characterized by classical techniques combining chemical analyses (liquid analyses, transmission electron microscopy combined with Energy Dispersive of X-rays spectroscopy TEM-EDS), mineralogical (X-ray diffraction), spectroscopic (57Fe Moessbauer) and morphometric techniques (TEM, scanning electron microscopy and N2 adsorption). For COx, COxCF and all the pure clay phases, major evolutions were observed during the first month, which shows that the oxidation of metallic iron is rapid in our experimental conditions. Release of iron cations in solution, pH increase (8-10) and Eh decrease (reductive conditions) are responsible for the partial dissolution of initial clay phases. Released iron is involved in the crystallization of Fe

  15. Long term monitoring of water production flow rates in boreholes in the Callovo-Oxfordian argillaceous rock

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Water production was observed in several boreholes in the Callovo-Oxfordian argillaceous rock (COx). These boreholes were implemented in 2005 in the Andra's Underground Research Laboratory (URL) at more than 400 m in depth. Despite the low COx permeability: close to 10-13 m/s, two original experimental setups made it possible to monitor water production flow rates ranging from 0.5 to 50 mL/day during 3 to 4 years in 4 boreholes. This contribution describes the water flow rate evaluation methods and the results obtained from several experimental phases which may be considered as a series of constant pressure production tests. The first experimental concept was based on seepage water collection. It consisted in filling with gas the interval of an ascending borehole at a pressure close to 1 bar and closing it. The hydraulic pressure in the rock surrounding the sealed interval was higher than 30 bars. Due to the hydraulic pressure difference between the interval and the surrounding rock, the interstitial water of the formation flowed into the interval, accumulated at its base by gravity and was pumped out at a controlled flow rate. The pumping rate was adjusted so that the water level would not exceed 40 cm inside the 5-meter-long interval. The water level was deduced from the difference between two absolute pressure measurements: one above the water surface in the gas phase and the other at the bottom of the water column. The total volume of the daily produced formation water was obtained by adding the water volume pumped out during the day and the water volume difference inside the interval between the beginning and the end of the day. This kind of experiment was performed in two boreholes. The second experimental concept was based on water circulation. It consisted in filling with water the interval of a descending borehole. Two water circulation lines and one pressure control line linked the test interval to

  16. Solution controls for dissolved silica at 25, 50 and 90 deg. C for quartz, Callovo-Oxfordian clay-stone, illite and MX80 bentonite

    International Nuclear Information System (INIS)

    Clay host rock and engineered barrier systems are the key elements in the concept adopted by several countries to isolate the high level nuclear waste from the biosphere. Mainly composed by illite, mixed-layer illite-smectite (I/S) and montmorillonite, these clays are characterized by their properties of high retention and low permeability for released radionuclides. After closure of the repository in deep geological formation, groundwater in equilibrium with the host rock, forming the pore water, will saturate the engineered barrier system and come in contact with the nuclear glass waste package. The leaching of the different silicate minerals as well as the uptake of dissolved silicic acid by these phases is an important factor in the dissolution of the nuclear glass waste. To understand how the Si interacts with clay materials, this study aims at evaluating the solubility as well as the dynamics of solid/solution exchange reactions, which control the dissolved silicic acid concentration in solution in contact with Callovo-Oxfordian clay-stone. The results were compared with the dissolution of illite, bentonite and quartz at 25, 50 and 90 deg. C in pore water. The experiments were conducted in batch system and in controlled atmosphere conditions and were followed in continue until the equilibrium between the solid and solution is reached. The results present a stabilization of the pH-values at 8.2 after 211 days for all the samples. The nature of solids and the temperature were not the determining factors on the pH-value but the chemical composition of the pore water and the working atmosphere (here, nitrogen). Dissolution and precipitation rates were calculated from the concentration of Si released from solids and the activity of 32Si-radiotracer added in solution, respectively. Dissolution rates were in the range of (8.7±0.4) x 10-12-(6.8±0.3)x10-11 mol Si/m2/s for quartz, (1.6±0.1) x 10-13-(6.4±0.3) x 10-13 mol Si/m2/s for Callovo-Oxfordian clay-stone, (2

  17. What can we learn from existing in situ cement based materials/Callovo-Oxfordian argillite interface sampled in the ANDRA underground research laboratory?

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Within the French concepts, concrete will be used to build access structures, galleries as well as vaults and waste packages for Intermediate Level Wastes (ILW). The assemblage of natural (host rock) and engineered barriers (bentonite and cement materials) used in storage cells (eg. plugs for sealing, support materials for the access gallery), provides numerous interfaces with contrasting geochemical conditions. The main goals of this study are linked to the knowledge of the chemical and physical evolution with time at the clay/cement based materials interface, in order to assess: (1) the kinetic and the extension of the degradation of the Callovo-Oxfordian argillite under the influence of alkaline plume. These interactions could modify the mineralogy and the transport properties of the rock (eg. porosity clogging induced by secondary minerals formation); (2) the concrete chemical degradation under the influence of the clay pore water. (concrete carbonation, hydrolysis with physical consequences especially with regards to transfer properties). To tackle this issue, two existing contacts between Callovo-Oxfordian argillite and cement based materials were sampled in the ANDRA (French Radioactive Waste Management Agency) Underground Research Laboratory (Meuse/Haute Marne, France) in order to describe in situ alkaline degradations in terms of mineralogy, chemistry, physical and textural parameters. (1) The first contact (A) concerns short-crested concrete in the access gallery. These samples which experienced 4 to 5 years of contact were drilled from the wall of the gallery. They offer the opportunity to describe on both sides (i) the alteration of the concrete link to the ventilation of the access gallery (atmosphere/concrete interface) and (ii) the concrete/clay interfaces. (2) The second one (B) deals with a bore hole fulfilled with a cement which also experienced 4 to 5 years of contact with the argillaceous media

  18. Full scale 3D-modelling of the coupled gas migration and heat dissipation in a planned repository for radioactive waste in the Callovo-Oxfordian clay

    International Nuclear Information System (INIS)

    An important question related to the long-term safety performance of a repository for long-lived medium and high-level radioactive waste in the Callovo-Oxfordian clay unit is the impact of heat and gas generated in the waste emplacement areas on the gas and water pressure and on the water saturation in the backfilled repository and in the host rock. The current design of such a repository consists of a multitude of different underground structures, such as emplacement drifts for waste canisters and other types of waste packages, access and ventilation drifts, and access shafts in the central part of the repository. The individual underground structures exhibit different thermo-hydraulic and geometrical properties yielding a large and complex system for the flow and transport of gas, water and heat. A detailed 3D modelling of the entire repository would require a tremendous computational effort, even when using high performance simulator codes. A newly developed method (Poller et al., 2011) allows for the 3D modelling of the two-phase gas-water flow and thermal evolution in the entire repository/host-rock system in a simplified manner. Besides accounting for both the detailed structures at local scale and the global geometry of the drift network, it also allows for an assessment of the gas phase pressure as well as the hydrogen and heat fluxes developing over the complete lifetime of the repository system. In this paper, the results of a reference scenario are presented. The assessment focuses on the two dominant processes, i.e. the dissolution. and. diffusion of the generated hydrogen, and the advective migration of the forming hydrogen gas phase in space and time (up to 1 million years). Further, the main findings of a sensitivity analysis on different features, physical processes and parameter uncertainty are presented. (authors)

  19. Contributions to micromechanical model of the non linear behavior of the Callovo-Oxfordian argillite; Contributions a la modelisation micromecanique du comportement non lineaire de l'argilite du callovo-oxfordien

    Energy Technology Data Exchange (ETDEWEB)

    Abou-Chakra Guery, A

    2007-12-15

    This work is performed in the general context of the project of underground disposal of radioactive waste, undertaken by the French National Radioactive Waste Management Agency (ANDRA). Due to its strong density and weak permeability, the formation of Callovo-Oxfordian argillite is chosen as one of possible geological barriers to radionuclides. The objective of the study to develop and validate a non linear homogenization approach of the mechanical behavior of Callovo-Oxfordian argillites. The material is modelled as a composite constituted of an elasto(visco)plastic clay matrix and of linear elastic or elastic damage inclusions. The macroscopic constitutive law is obtained by adapting the incremental method proposed by Hill. The derived model is first compared to Finite Element calculations on unit cell. It is then validated and applied for the prediction of the macroscopic stress-strain responses of the argillite at different geological depths. Finally, the micromechanical model is implemented in a commercial finite element code (Abaqus) for the simulation of a vertical shaft of the underground laboratory. This allows predicting the distribution of damage state and plastic strains and characterizing the excavation damage zone (EDZ). (author)

  20. Performance assessment of repositories in the Callovo-Oxfordian clay considering diversified gas and heat generation regimes and two geometrical layouts

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. All French high-level (HA) and intermediate-level long-lived (MAVL) radioactive waste is planned to be disposed of in a single deep geological repository. Andra identified the Callovo-Oxfordian (COx) argilites in north-eastern France as a suitable host rock. The repository is planned to be situated at around 500 metres below the surface in the Callovo-Oxfordian clay. The repository consists of a system of drifts and shafts holding the waste in several thousand waste emplacement cells in distinguished sectors for HA and MAVL waste. Depending on the layout the system covers a horizontal area of 10 to 20 square kilometres. With the start of the construction of the repository the natural conditions in the COx are disturbed. The initially fully saturated rock is drained by the drifts and shafts which are ventilated during construction and operation leading to pressure differences and water flow in the host rock. Some of the emplaced wastes release significant amounts of heat that is mainly produced by the continuing radioactive decay. This heat load represents a disturbance of the thermal balance of the host rock influencing the pressure regime as well. With emplacement, backfill, and closure of the repository the metal components of the waste and constructional elements start to corrode. In the anoxic regime, this corrosion produces significant amounts of hydrogen, which induces desaturation effects and further impacts the pressure. Heat and gas generation and their influence on the system last for up to several ten thousand years. For the assessment of the performance of a repository an accurate estimate of the maximum pressure that occurs over the lifetime of the repository, which is postulated to be one million years, is essential. The host rock represents the natural barrier that assures the isolation of the waste from the environment. A too high pressure or temperature could deteriorate this barrier effect

  1. Micro-mechanics based modeling of the Callovo-Oxfordian argillite mechanical behavior; Modelisation micro-macro du comportement elastoplastique endommageable de l'argilite du Callovo-Oxfordien

    Energy Technology Data Exchange (ETDEWEB)

    Abou-Chakra Guery, A.; Cormery, F.; Shao, J.F.; Kondo, D. [Laboratory of Mechanics of Lille, UMR 8107, 59 - Villeneuve d' Ascq (France); Abou-Chakra Guery, A. [Agence Nationale pour la Gestion des Dechets Radioactifs (ANDRA), 92 - Chatenay Malabry (France)

    2007-05-15

    The present study is devoted to the development and validation of a non-linear homogenization approach of the mechanical behavior of Callovo-Oxfordian argillites. The material is modelled as an heterogeneous one composed of an elastoplastic clay matrix and of linear elastic or elastic damage inclusions. The macroscopic constitutive law is obtained by adapting the Hill-type incremental method [1]. The approach consists in formulating the macroscopic tangent operator of the material from the non-linear local behavior of its phases. Due to the matrix/inclusion morphology of the microstructure of the argillites, a Mori-Tanaka scheme is considered for the localization step. The developed model is first compared to Finite-Elements calculations and then validated and applied for the prediction of the macroscopic stress-strain responses of argillites. (authors)

  2. Determination of hydraulic properties of the Callovo-Oxfordian argillite at the Bure site: synthesis of the results obtained in deep boreholes using several in-situ investigation techniques

    International Nuclear Information System (INIS)

    Over the last years, Andra has collected an impressive amount of hydraulic data on the middle Jurassic, Callovo-Oxfordian argillite at a site located 300 km eastern from Paris. Preliminary analyses of the formation pressure (freshwater potential) and the hydraulic conductivity have been performed based on the hydraulic data of both the short term packer tests and the long term monitoring (EPG and Westbay). This was performed using numerical borehole simulators which enable taking into account the complete pressure history of the borehole, defining a suitable flow model and deriving best guess estimates and uncertainty ranges of the hydraulic parameters. For all measurement intervals investigated In-Situ, it was shown that the hydraulic conductivity was less than 2,10-12 m/s. A comparison of the preliminary results of the packer tests and those of the long term pressure monitoring shows that the short term packer tests tend to highly over-estimate the formation pressure. The hydraulic conductivities obtained from the analysis of the packer tests are mostly higher than those obtained from the analysis of the EPG long term recovery. Further analyses are planned to check these preliminary analyses as well as the consistency between short term and long term measurements providing information on rock properties at different scales (different radius of visibility). (authors)

  3. Microbial investigations in Opalinus clay from Mont Terri and in Callovo-Oxfordian argillite from Meuse/Haute-Marne; Caracterisation microbiologique de l'argile a opalinus du Mont Terri et de l'argilite du callovo-oxfordien de Meuse/Haute-Marne

    Energy Technology Data Exchange (ETDEWEB)

    Poulain, S

    2006-12-15

    The subject of this Ph.D. thesis deals with research achieved in the context of the Axis 2 of the law Bataille voted on December 30, 1991 about the possibility of building a deep geological repository for medium or high activity and long living nuclear waste. Nearby such a site, some microorganisms may influence the mobility of radionuclides coming from the waste canisters. This work consisted in looking for autochthonous microorganisms in the Opalinus clay formation from Mont Terri (Switzerland) and in the Callovo-Oxfordian argillite from Meuse/Haute-Marne (France). Microbial Investigations in these unknown unperturbed environments suggested very low microbial densities in the clayey sediments. However, new bacterial species could be isolated from those samples. In addition, a part of the allochthonous population, which has been introduced by air and human activity, could be identified in the Meuse/Haute-Marne underground research laboratory. (author)

  4. Microbiological study of a crushed 'core heart' packaged under sterile atmosphere and isolation of different bacterial strains from the Callovo-Oxfordian argillaceous rock (Bure, France)

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. To study the feasibility of a reversible storage of high activity and long life radioactive waste, many parameters have to be take into account, including microbiological parameters. Indeed, it is necessary to determine the extent of biological reactions that could develop in a disposal. For example, processes such as canister corrosion, retention and transport of radionuclides and gas production may be partially mediated by microbial activities. An initial microbiological characterization of the Callovo- Oxfordian clay-rock was conducted in 2006 by S. Poulain. This previous work highlighted a number of bacterial strains responsible for the disturbances of some geochemical parameters observed in experiments performed in the Andra's Meuse/Haute-Marne Underground Research Laboratory (URL). A thoroughly metabolic study on each isolated strain was then launched after a new phase of microorganism isolation. The purpose of this new study is to analyse the gas produced by bacteria (like CO2, H2 or H2S) and the products of their metabolism, in particular corrosive molecules. The microflora was mainly studied on solid samples. These samples came from a 5-m long borehole drilled using aseptic techniques on June, 2009. All parts of the drilling equipment were cleaned with bleach, rinsed with demineralized water, and wrapped in sterile foil and clean plastic, prior to arrival on site. The equipment was handled with ethanol-sterilized gloves and when needed (i.e., after each retraction from the borehole to remove core sections), re-cleaned on site with ethanol. The borehole was drilled with compressed N2 to avoid air contamination. After retrieval of the cores, they were conditioned on site on a conditioning table prepared for working under clean conditions. The sample were placed in sterile plastic bags, flushed with filter-sterilized N2 and closed by thermal sealing at ambient temperature. The samples were further packed

  5. Tracing of natural radionuclides mobility in deep sedimentary environment using radioactive (234U/238U) disequilibria: application to the Mesozoic formations of the Eastern part of the Paris Basin

    International Nuclear Information System (INIS)

    This thesis forms part of the geological investigations undertaken by the French agency for nuclear waste management, ANDRA, around the Meuse/Haute-Marne Underground Research Laboratory (URL) located in the Eastern part of the Paris Basin in order to evaluate the feasibility of high-level radioactive waste repository in deep argilite formations. The aim of the study is to examine the radionuclide migration in the deep Callovo-Oxfordian target argilite layer and its surrounding low- permeability Bathonian and Oxfordian limestone formations in order to assess the long term confining capacities of the sedimentary series. This study is based on measurement of radioactive disequilibria within U-series by Multiple- Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS). The high precision and accuracy achieved allowed to demonstrate the 234U/238U radioactive equilibrium in the Callovo-Oxfordian argilites. This result shows the uranium immobility in the target formation and provides a strong evidence for the current chemical stability and closure of the system for uranium and most probably for the other actinides. This is a fundamental result with respect to the problematic of disposal of high level radioactive waste in deep geological formation since it provides a in situ indication of the confining capacities of the clayey target formation in the current settings. Conversely, (234U/238U) disequilibria are systematically observed within zones, located in the surrounding carbonate formations, that are characterized by pressure dissolution structures (stylolites or dissolution seams). These disequilibria provide evidence for a discrete uranium relocation during the last two million years in the vicinity of stylolitic structures. This is a surprising result since it is generally supposed that these deep, low permeability, compact formations behave as closed system at the time scale of the U-series. (author)

  6. Tracing of natural radionuclides mobility in deep sedimentary environment using radioactive ({sup 234}U/{sup 238}U) disequilibria: application to the Mesozoic formations of the Eastern part of the Paris Basin; Tracage de la mobilite des radionucleides naturels en milieu sedimentaire profond a l'aide des desequilibres radioactifs ({sup 234}U/{sup 238}U): application aux formations mesozoiques de l'est du Bassin de Paris

    Energy Technology Data Exchange (ETDEWEB)

    Deschamps, P

    2003-11-01

    This thesis forms part of the geological investigations undertaken by the French agency for nuclear waste management, ANDRA, around the Meuse/Haute-Marne Underground Research Laboratory (URL) located in the Eastern part of the Paris Basin in order to evaluate the feasibility of high-level radioactive waste repository in deep argilite formations. The aim of the study is to examine the radionuclide migration in the deep Callovo-Oxfordian target argilite layer and its surrounding low- permeability Bathonian and Oxfordian limestone formations in order to assess the long term confining capacities of the sedimentary series. This study is based on measurement of radioactive disequilibria within U-series by Multiple- Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS). The high precision and accuracy achieved allowed to demonstrate the {sup 234}U/{sup 238}U radioactive equilibrium in the Callovo-Oxfordian argilites. This result shows the uranium immobility in the target formation and provides a strong evidence for the current chemical stability and closure of the system for uranium and most probably for the other actinides. This is a fundamental result with respect to the problematic of disposal of high level radioactive waste in deep geological formation since it provides a in situ indication of the confining capacities of the clayey target formation in the current settings. Conversely, ({sup 234}U/{sup 238}U) disequilibria are systematically observed within zones, located in the surrounding carbonate formations, that are characterized by pressure dissolution structures (stylolites or dissolution seams). These disequilibria provide evidence for a discrete uranium relocation during the last two million years in the vicinity of stylolitic structures. This is a surprising result since it is generally supposed that these deep, low permeability, compact formations behave as closed system at the time scale of the U-series. (author)

  7. Lithology, hydro-dynamism and thermicity in the multi-layer sedimentary system intersected by the Andra deep borehole of Montiers-sur-Saulx (Meuse, France)

    International Nuclear Information System (INIS)

    Andra (French national radioactive waste management agency) has conducted a research program to determine the feasibility of a disposal facility for long-lived high level and medium level (LL-HLML) nuclear wastes in a deep geological environment. In 2005, following 15 years of research, Andra established the feasibility of this type of disposal in the Callovo-Oxfordian clay formations located in the eastern region of the Paris basin. Between 2006 and 2008, a geological survey campaign was carried out over 250 km2 at the boundary of the Meuse and Haute-Marne departments. Six drilling platforms were involved on the studied zone and a 2D seismic campaign was carried out using a 2 x 2 km to 3 x 3 km grid as regular as possible. One of the drilling platforms was located in the central area of the studied zone, at a distance of the faults located at the boundary of the studied sector. Three boreholes called EST431, EST432 and EST433 were drilled from this platform. Their main objectives were to contribute to the sitting of the disposal facility, and enhance the knowledge on the formations overlying and underlying the host layer (Dogger, carbonated Oxfordian and Kimmeridgian), as well as on the deep Lias and Trias formations. More specifically, it is meant (i) to acquire a better understanding of the global functioning of the hydrogeological System and the vertical exchanges between the formations and (ii) to assess the potential geothermal resources on the zone in order to verify the absence of exceptional exploitable resources in the vicinity of the site earmarked for the disposal facility. Beyond these objectives, Andra associated the French scientific community to the exploitation of the results yielded by this borehole. Thus, as early as the design stage, Andra entered into a partnership with university laboratories through a program called 'Current and Past transfers in an Aquiferous - Aquitard Sedimentary System'. The partner laboratories were able to carry out

  8. Analysis of water/gas flows in argillites from Callovo-Oxfordian using gradient percolation

    International Nuclear Information System (INIS)

    The work presented in this manuscript is motivated by the study of nuclear waste underground repository. In this context, we study the hyper slow drainage problem, which is related to the gas production, mainly hydrogen, taking place within the repository. Although the gas production rate is quite small, and thus the drainage hyper slow, the amount of produced gas is quite significant because the production takes place over thousands years. The study is performed within the framework of the theory of invasion percolation in a gradient. We first show that the hyper slow drainage process can be modelled using the traditional two-phase flow model based on the generalized Darcy's law. A crucial step is then to specify properly the parameters of the model. We show how they must be specified from the asymptotic behaviours of the parameters for an infinite medium as predicted by percolation theory. The obtained solution indicates that the hyper slow drainage operates in the vicinity of breakthrough pressure, which is the subject of a specific study. Furthermore, the hyper slow drainage is characterized by a weak desaturation of the medium and a great sensitivity to the model parameters in the range of high wetting fluid saturation. We also study the impact of coupling between the flow and the local deformation of porous matrix at the pore network scale from numerical simulations using a model coupling a pore network model and a deformation model based on a system of interconnected springs. The simulations indicate a major change of the invasion pattern compared to the rigid matrix with the self-generation of invasion preferential paths when the coupling is sufficiently strong. (author)

  9. Direct observations of the 3D pore network of a Callovo-Oxfordian clay-stone

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Long term deep underground storage of radioactive nuclear waste is planned in the East of France within an argillaceous rock layer (the host rock), also called argillite, situated at ca. 450-500 m depth. Andra, the French national agency for nuclear waste management, is in charge of assessing the feasibility, the safety and the performance of this underground disposal. The drilling of storage tunnels generates an Excavated Damaged Zone (EDZ), where argillite is macro-cracked in various locations. This requires strengthening by different means, e.g. shotcrete or pre-fabricated concrete arches. It is also expected that underground water seepage will contribute to argillite sealing: mainly self-sealing, and sealing at the interface with concrete. Sealing phenomena include crystalline swelling of smectitic clay components of argillite and inter-particle swelling of clay minerals due to osmosis mechanisms. Small scale pores and mineral organisation of the COx clay-stone are widely acknowledged to control transfer properties of water, gas and varied solutes. In order to assess these properties, the COx small-scale structure has been imaged down to micrometric resolution by various means, including classical Scanning Electron Microscopy (SEM), X-ray computed microtomography and autoradiography. To go further into pore and mineral characterisation of COx clay-stone, the following investigations are currently under way: (i) acquiring/quantifying the 3D geometry of the pore network of undisturbed COx with a nano-metric resolution and (ii) imaging/quantifying the small-scale (mm-nm) structure of self-sealed volumes. The FIB (Focused Ion Beam) /SEM technique allows performing 3D observations of solid volumes of ca. a few microns, with a resolution of about ten nanometers, by acquiring and computing regularly spaced 2D SEM images. This technique provides quantification of the 3D spatial distribution mainly of macro- and meso-pores. This technique was first applied on undisturbed COx samples, corresponding to the host rock located further away from the EDZ. Using the raw FIB/SEM images, specific image analysis methods were applied to extract the 3D pore network. The main features of this pore geometry were analyzed. General good agreement is observed when comparing to pore size distributions derived from first desorption isotherms. With the FIB/SEM imaging method, pore anisotropy (preferential orientation and elongation), related to the bedding plane, is highlighted. This is characteristic of pores located within clay particles, currently down to 40-50 nm. Further work to be presented to this conference will include smaller distance between each successive 2D FIB/SEM images, in order to access to smaller pores, and images of self-sealed zones using microtomography, classical SEM observations and FIB/SEM. Based on the 3D spatial distribution of pores, transfer phenomena modelling is planned, in order to predict radionuclide diffusion, multiphase transport, gas passage through argillite, etc. These simulations will range from the pore size scale up to the macroscopic scale, where mechanical and transport property assessment is available. (authors)

  10. Study of the argillaceous fraction of sedimentary sequences of Meuse and Gard. Reconstitution of the diagenetic history and of the physico-chemical characteristics of the targets. Mineralogical, geochemical and isotopic aspects

    International Nuclear Information System (INIS)

    Very low permeable argillaceous rocks like Callovo-Oxfordian clay-stones or Vraconian siltstones were chosen to host a research laboratory built to determine the physico-chemical properties of the host formations for a potential underground disposal of radioactive waste. Knowledge and understanding of post-sedimentary modifications are of prime importance for definition of these properties; evaluation and quantification of the post-sedimentary changes represent the aim of this study, focused specifically on the clay material of the sequences. Samples were taken from two drillings (HTM102 and MAR501). In the HTM102 core samples, illite and mixed-layers illite/smectite are the dominant clay components of most clay fractions. Systematic SEM and TEM observations and isotopic K-Ar and Rb-Sr analyses pointed to diagenetic neo-formations of carbonates (calcite, dolomite) and clays. For instance, veils and laths of authigenic clay particles around old detrital ones can distinctly be observed. The epoch, duration and extent of the diagenetic activity(ies) are difficult to evaluate because of an overall detrital contribution even in the finest granulometric fractions. However; analysis of a bentonite layer in the sequence provides a diagenetic reference for the authigenic clay material. Correlation between relative sea level and authigenesis of smectite-rich mineral has been outlined. Chemistry of diagenetic fluids also seems to be reliable with sea level variations. These observations argue in favour of diagenetic activities limited in restricted rock volumes. The case study of MAR501 is close to the HTM102 one: smectite-rich illite/smectite mixed-layers represent the major component of the clay fraction and K-Ar values argue ire the sense of a mixing between detrital and younger clay populations. Diagenetic glauconites in the sequence yield are age close to 93,7 ±0,3 Ma for Vraconian level, in agreement with stratigraphical data. The case study of a clay-filled fault

  11. Study of the argillaceous fraction of sedimentary sequences of Meuse and Gard. Reconstitution of the diagenetic history and of the physico-chemical characteristics of the targets. Mineralogical, geochemical and isotopic aspects; Etude de la fraction argileuse de sequences sedimentaires de la Meuse et du Gard. Reconstitution de l'histoire diagenetique et des caracteristiques physico-chimiques des cibles. Aspects mineralogiques, geochimiques et isotopiques

    Energy Technology Data Exchange (ETDEWEB)

    Rousset, D

    2002-01-01

    Very low permeable argillaceous rocks like Callovo-Oxfordian clay-stones or Vraconian siltstones were chosen to host a research laboratory built to determine the physico-chemical properties of the host formations for a potential underground disposal of radioactive waste. Knowledge and understanding of post-sedimentary modifications are of prime importance for definition of these properties; evaluation and quantification of the post-sedimentary changes represent the aim of this study, focused specifically on the clay material of the sequences. Samples were taken from two drillings (HTM102 and MAR501). In the HTM102 core samples, illite and mixed-layers illite/smectite are the dominant clay components of most clay fractions. Systematic SEM and TEM observations and isotopic K-Ar and Rb-Sr analyses pointed to diagenetic neo-formations of carbonates (calcite, dolomite) and clays. For instance, veils and laths of authigenic clay particles around old detrital ones can distinctly be observed. The epoch, duration and extent of the diagenetic activity(ies) are difficult to evaluate because of an overall detrital contribution even in the finest granulometric fractions. However; analysis of a bentonite layer in the sequence provides a diagenetic reference for the authigenic clay material. Correlation between relative sea level and authigenesis of smectite-rich mineral has been outlined. Chemistry of diagenetic fluids also seems to be reliable with sea level variations. These observations argue in favour of diagenetic activities limited in restricted rock volumes. The case study of MAR501 is close to the HTM102 one: smectite-rich illite/smectite mixed-layers represent the major component of the clay fraction and K-Ar values argue ire the sense of a mixing between detrital and younger clay populations. Diagenetic glauconites in the sequence yield are age close to 93,7 {+-}0,3 Ma for Vraconian level, in agreement with stratigraphical data. The case study of a clay-filled fault

  12. Transferability of geodata from European to Canadian (Ontario) sedimentary rocks to study gas transport from nuclear wastes repositories

    International Nuclear Information System (INIS)

    , most of these studies, especially the gas migration tests, were conducted in European sedimentary rocks (Opalinus Clay in Benken and Mont Terri, Callovo-Oxfordian Clay at Bure). At present, gas transport data specific for Ontario sedimentary rocks are not available; the input parameters for mathematical models have to be inferred from the European database. This paper presents a methodological approach and the results of a study to assess the usefulness and transferability of geo-data from European to Ontario sedimentary rocks to model the THMC processes associated with gas migration in Ontario. Furthermore, predictive models (based on advanced soft-computing methods) to estimate the gas transport parameters of the Ontario rocks from data on European sedimentary rocks are presented and discussed. The paper is divided into three main parts: - In the first part, the main similarities and differences between the thermal, hydraulic, geochemical and geomechanical properties of the host rocks of the proposed Ontario DGR and European DGRs are highlighted and discussed, based on a comparison of the collected technical information on sedimentary rocks in Ontario and Europe. - The second part includes an analysis of the quality (e.g., uncertainties), suitability and transferability of the data gathered with respect to the investigation of gas generation and migration in a potential repository in Ontario's sedimentary rocks. - In the third part, a quantitative analysis of the transferability of the data is conducted by using advanced soft computing methods (e.g., Self Organizing Neuro-Fuzzy Inference System (SONFIS)). Predictive models are developed to predict the relevant parameters that are necessary to model and analyze gas transport in the study DGR in Ontario. The validation results show good agreement between the predicted and measured field values. In conclusion, this study has allowed us to identify the similarities and differences between the Ontario and European

  13. Contribution to the study of mechanical and thermo-hydro-mechanical behaviour of Callovo-Oxfordian argillites. Application to radioactive waste storage

    International Nuclear Information System (INIS)

    This Habilitation thesis presents a synthesis of the different mechanical and thermo-hydro-mechanical coupled aspects of rocks and in particular it deals with a)the phenomena and processes coupled with mechanics in a storage (ch 1); b)the behavior of argillites under thermal, mechanical and coupled hydro-mechanical and thermo-hydro-mechanical solicitations (ch 2 to 4); c)the rheological models and the argillites behavior simulations (ch 5). (O.M.)

  14. Hydrogen solubility in pore water of partially saturated argillites: Application to Callovo-Oxfordian clay-rock in the context of a nuclear waste geological disposal

    International Nuclear Information System (INIS)

    In nuclear waste geological disposals, large amounts of hydrogen (H2) are expected to be produced by different (bio-)geochemical processes. Depending on the pressure generated by such a process, H2 could be produced as a gas phase and displace the neighbouring pore water. As a consequence, a water-unsaturated zone could be created around the waste and possibly affect the physical and physic-chemical properties of the disposal and the excavation disturbed zone around it. The present study is the first part of an ongoing research program aimed at evaluating the possible chemical evolution of the pore water-minerals-gas system in such a context. The goal of this study was to evaluate, in terms of thermodynamic equilibrium conditions, the geochemical disturbance of the pore water due to variations in hydrogen pressure, temperature and relative humidity. No heterogeneous reactions involving mineral phases of the clay-rock or reactive surface sites were taken into account in the thermodynamic analysis. In the case sulphate reduction reaction is allowed, geochemical modelling results indicate that the main disturbance is the increase in pH (from around 7 up to more than 10) and an important decrease in the redox potential (Eh) related to hydrogen dissolution. This occurs from relatively low H2 partial pressures (∼1 bar and above). Then, temperature and relative humidity (expressed in terms of capillary pressure) further displace the thermodynamic equilibrium conditions, namely the pH and the aqueous speciation as well as saturation indices of mineral phases. Finally, the results suggest that the generation of hydrogen, combined with an increase in temperature (between 30 deg. C and 80 deg. C) and a decrease in relative humidity (from 100% to 30%), should increase the chemical reactivity of the pore water-rock-gas system. (authors)

  15. Dealing with geological discontinuities in safety assessment: the approach of the French technical safety organisation

    International Nuclear Information System (INIS)

    The present paper focuses on IRSN structural studies aiming at assessing the existence of tectonic structures in the Callovo-Oxfordian clay formation and their potential role on radionuclide transport. IRSN has first determined the type of fracturing that could be present in the Callovo-Oxfordian, by carrying out surface fieldwork in Meuse/Haute-Marne and investigations in clay and limestone layers in the Tournemire experimental station. IRSN has also examined the results of the ANDRA 3-D seismic survey associated with inclined boreholes around the Bure URL, as well as the limits of these survey methods, based on its own 3-D High-Resolution seismic survey campaign carried out in Tournemire on fault zones already recognised by drifts and boreholes. At the scale of the Paris sedimentary basin, on the basis of a geological model and of measured hydrodynamic parameters, IRSN has developed underground water flow schemes, which allow the determination of possible water pathways, outlets and associated transfer times. This modelling shows that several combinations in the representation of tectonic structures are possible to fit measured data, and that the remaining uncertainties regarding their hydrogeological role should be reduced. In addition, the influence of a hypothetic fault in the Callovo-Oxfordian clay close to disposal cells on radionuclide molar flows is tested at the repository scale. At last, perspectives are given regarding in particular methods to detect hydro-geologically active faults, differential fracturing patterns in clays and limestones as well as improvement of IRSN hydrogeological model. (authors)

  16. Clay minerals in the Meuse - Haute Marne underground laboratory (France): Possible influence of organic matter on clay mineral evolution.

    OpenAIRE

    Claret, Francis; Sakharov, Boris.A.; Drits, Victor.A.; Velde, Bruce; Meunier, Alain; Griffault, Lise; Lanson, Bruno

    2004-01-01

    A clay-rich Callovo-Oxfordian sedimentary formation was selected in the eastern Paris Basin (MHM site) to host an underground laboratory dedicated to the assessment of nuclear waste disposal feasibility in deep geological formations. As described initially, this formation shows a mineralogical transition from an illite-smectite (I-S) mixed-layered mineral (MLM), which is essentially smectitic and randomly interstratified (R=0) in the top part of the series to a more illitic, ordered (R≥1) I-S...

  17. Mass Transfer and Porous Media (MTPM)

    Energy Technology Data Exchange (ETDEWEB)

    Rotenberg, B.; Marry, V.; Malikova, N.; Vuilleumier, R.; Giffaut, E.; Turq, P.; Robinet, J.C.; Diaz, N.; Sardini, P.; Goutelard, F.; Menut, D.; Parneix, J.C.; Sammartino, S.; Pret, D.; Coelho, D.; Jougnot, D.; Revil, A.; Boulin, P.F.; Angulo-Jaramillo, R.; Daian, J.F.; Talandier, J.; Berne, P.; Cochepin, B.; Trotignon, L.; Bildstein, O.; Steefel, C.; Lagneau, V.; Van der Lee, J.; Birchall, D.J.; Harrington, J.F.; Noy, D.J.; Sellin, P.; Bildstein, O.; Piault, E.; Trotignon, L.; Montarnal, P.; Deville, E.; Genty, A.; Le Potier, C.; Imbert, C.; Semete, P.; Desgree, P.; Fevrier, B.; Courtois, A.; Touze, G.; Sboui, A.; Roberts, J.E.; Jaffre, J.; Glaus, M.A.; Rosse, R.; Van Loon, L.R.; Matray, J.M.; Parneix, J.C.; Tinseau, E.; Pret, D.; Mayor, J.C.; Ohkubo, T.; Kikuchi, H.; Yamaguchi, M.; Alonso, U.; Missana, T.; Garcia-Gutierrez, M.; Patelli, A.; Siitari-Kauppi, M.; Leskinen, A.; Rigato, V.; Samper, J.; Dewonck, S.; Zheng, L.; Yang, Q.; Naves, A.; Dai, Z.; Samper, J.; Wolfsberg, A.; Levitt, D.; Cormenzana, J.L.; Missana, T.; Mingarro, M.; Schampera, B.; Dultz, S.; Riebe, B.; Samper, J.; Yang, Q.; Genty, A.; Perraud, D.; Poller, A.; Mayer, G.; Croise, J.; Marschall, P.; Krooss, B.; Matray, J.M.; Tanaka, T.; Vogel, P.; Lavanchy, J.M.; Enssle, C.P.; Cruchaudet, M.; Dewonck, S.; Descostes, M.; Blin, V.; Radwan, J.; Poinssot, C.; Mibus, J.; Sachs, S.; Devol-Brown, I.; Motellier, S.; Tinseau, E.; Thoby, D.; Marsal, F.; DeWindt, L.; Tinseau, E.; Pellegrini, D.; Bauer, A.; Fiehn, B.; Marquardt, Ch.; Romer, J.; Gortzen, A.; Kienzler, B

    2007-07-01

    protocol for the investigation of diffusion of ions through argillaceous barriers; the gas permeability of an argilite: measurements and parameters identification; CORE2D V4: A general purpose code for groundwater flow, heat and solute transport, chemical reactions and biological processes in porous and fractured media; the hyper-filtration of metal solutions through low-permeability media and its effects on hydraulic conductivity; the argillites thermal conductivity variations induced by sedimentary/diagenetic processes and by mechanical decompression; the porosity network geometry and inferred permeability of the Callovo-Oxfordian argillites from magnetic fabric and oriented mercury injections; the identification and quantification of large-scale diffusion in a deep clay-stone formation (Opalinus Clay of Mont Russelin, Switzerland); the reactive diffusion front driven by an alkaline plume in compacted Mg-homo-ionic bentonite; the transport number of sodium ions in water-saturated, compacted Na-Montmorillonite; the swelling, transport and gas threshold pressure of a sealing bentonite plug: effect of sand addition; species-specific transport and reactive transport modelling of a long-term core infiltration experiment on Opalinus clay; and modelling gas injection tests in deformable clay buffers.

  18. Mass Transfer and Porous Media (MTPM)

    International Nuclear Information System (INIS)

    investigation of diffusion of ions through argillaceous barriers; the gas permeability of an argilite: measurements and parameters identification; CORE2D V4: A general purpose code for groundwater flow, heat and solute transport, chemical reactions and biological processes in porous and fractured media; the hyper-filtration of metal solutions through low-permeability media and its effects on hydraulic conductivity; the argillites thermal conductivity variations induced by sedimentary/diagenetic processes and by mechanical decompression; the porosity network geometry and inferred permeability of the Callovo-Oxfordian argillites from magnetic fabric and oriented mercury injections; the identification and quantification of large-scale diffusion in a deep clay-stone formation (Opalinus Clay of Mont Russelin, Switzerland); the reactive diffusion front driven by an alkaline plume in compacted Mg-homo-ionic bentonite; the transport number of sodium ions in water-saturated, compacted Na-Montmorillonite; the swelling, transport and gas threshold pressure of a sealing bentonite plug: effect of sand addition; species-specific transport and reactive transport modelling of a long-term core infiltration experiment on Opalinus clay; and modelling gas injection tests in deformable clay buffers

  19. Construction of predictive models for radionuclide diffusion in sedimentary rocks applied to radioactive waste deep storage: approach and overview of the CEA research program

    International Nuclear Information System (INIS)

    Full text of publication follows: Deep geological storage is studied in France as one of the three potential options for managing long lived nuclear waste in the framework of the 1991 Law. One of the key topics of research deals with the behaviour of radionuclides in the geological environment, focusing in particular on the diffusion process within the rock. The final aim is to develop validated and reliable long-term predictive migration models. These researches are mainly coping with Jurassic-age Callovo-Oxfordian argilites. They include first some characterizations performed on core samples (diffusion tests, characterisation of porosity properties, chemical retention measurements). In fact, tests on small samples in diffusion cells under laboratory conditions are essential to obtain diffusion parameters used in safety calculations because they allow selection and control of experimental physical and chemical conditions and therefore constitute the principal tools for understanding and quantifying the underlying phenomena such as the effect of temperature, water composition, and lithological properties of the rocks. As a consequence, CEA performed for more than ten years several hundredths of through diffusion tests involving inert, anionic and cationic radioactive tracers on argilites and limestone samples. Tests conducted in diffusion cells do however have limitations because they apply to small samples. In addition, tests performed in surface laboratories are confronted with uncertainties relating to the determination of the in-situ water composition. Moreover, samples used in the surface laboratory may have been subjected to mechanical and chemical disturbances before the actual performance of the tests. It is therefore necessary to validate the extrapolation of the characterisation results of transport properties to larger scales. In-situ experiments help then in analysing the representativeness of physical models and associated parameters and support the

  20. Sedimentary Petrology: from Sorby to the globalization of Sedimentary Geology

    International Nuclear Information System (INIS)

    We describe here the most important milestones and contributions to Sedimentary Petrology compared to other geological disciplines. We define the main aim of our study and the scientific and economic interests involved in Sedimentary Petrology. The body of the paper focuses upon the historical development of this discipline from Henry Sorby's initial work until the present day. The major milestones in its history include: 1) initial descriptive works; 2) experimental studies; 3) the establishment of the different classifications of sedimentary rocks; 4) studies into facies and sedimentary environments; 5) advances in the study of diagenetic processes and their role in hydrocarbon prospection; and 6) the development of Sedimentary Geochemistry. Relationships and coincidences with Sedimentology are discussed. We go on to look at the advances that have taken place over the last 30 years, in which the study of sedimentary rocks is necessarily included in the wider field of Sedimentary Geology as a logical result of the proposal of global models of a changing Earth in which Sedimentary Geology plays a significant part. Finally we mention the notable contributions of Spanish sedimentary petrologists to this whole field of science. (Author) 120 refs.

  1. Contribution of natural tracers for understanding transfers through argillaceous formations

    International Nuclear Information System (INIS)

    This study is part of a research programme conducted by IRSN on the safety of deep geological disposal of high level and intermediate long-lived radioactive wastes. It more especially concerns the geological medium considered as a full component of the multi-barrier concept proposed by Andra for a deep repository. Indeed, the Callovo-Oxfordian argillite of the Paris Basin, in the east of France, is being investigated by Andra as a potential host rock for this repository. Performance assessment of this natural barrier is based on the knowledge of its confinement properties and therefore on phenomena possibly involved in the mass transport of radionuclides. In this context, this work aimed at studying the distribution of tracers naturally present in pore waters obtained from boreholes having crossed Mesozoic sedimentary series involving impervious and compacted clay rocks in the East (Andra borehole, EST433) and south of France (IRSN boreholes). Radial diffusion and vapour exchange methods were used to calculate the concentrations and diffusion parameters of the studied tracers. In Tournemire formations, the different profiles describe a curved shapes attributed to a diffusive exchange between the argillite pore water and the surrounding aquifers. Concerning the Mesozoic formations crossed by EST433, the study of the different profiles confirms the diffusion as the dominant transport mechanism in the Callovo-Oxfordian formation, and permits identifying the transport processes in the whole studied column from the Oxfordian formations down to the Liassic one. This study also helps to identify the Liassic formations as a major source of salinity of the Dogger aquifer

  2. Western Canada Sedimentary Basin competitiveness

    International Nuclear Information System (INIS)

    Recent dramatic expansion of the natural gas industry in the Western Canada Sedimentary Basin provided ample proof of the potential of this area for further development of natural gas supply. However, the inherent competitive advantages provided by the Western Canada Sedimentary Basin were said to have been offset by low netback prices resulting in poor producer economics when competitiveness is measured by availability of opportunities to find and develop gas supply at costs low enough to ensure attractive returns. Technology was identified as one of the key elements in improving basin competitiveness, but the greatest potential lies in reduced transportation costs and increased access to North American market centres. 8 figs

  3. Stratigraphy of neoproterozoic sedimentary and volcano sedimentary successions of Uruguay

    International Nuclear Information System (INIS)

    Based on the new data the different characteristics of the Neoproterozoic (volcano) sedimentary succesions of Uruguay are described and discussed. Their stratigraphic tectonics and palaeoclimatic implications are analyzed.The results of the present investigations also allow to define the Maldonado Group which would beintegrated by the Playa Hermosa and Las Ventanas formations.

  4. Quantitative characterisation of sedimentary grains

    Science.gov (United States)

    Tunwal, Mohit; Mulchrone, Kieran F.; Meere, Patrick A.

    2016-04-01

    Analysis of sedimentary texture helps in determining the formation, transportation and deposition processes of sedimentary rocks. Grain size analysis is traditionally quantitative, whereas grain shape analysis is largely qualitative. A semi-automated approach to quantitatively analyse shape and size of sand sized sedimentary grains is presented. Grain boundaries are manually traced from thin section microphotographs in the case of lithified samples and are automatically identified in the case of loose sediments. Shape and size paramters can then be estimated using a software package written on the Mathematica platform. While automated methodology already exists for loose sediment analysis, the available techniques for the case of lithified samples are limited to cases of high definition thin section microphotographs showing clear contrast between framework grains and matrix. Along with the size of grain, shape parameters such as roundness, angularity, circularity, irregularity and fractal dimension are measured. A new grain shape parameter developed using Fourier descriptors has also been developed. To test this new approach theoretical examples were analysed and produce high quality results supporting the accuracy of the algorithm. Furthermore sandstone samples from known aeolian and fluvial environments from the Dingle Basin, County Kerry, Ireland were collected and analysed. Modern loose sediments from glacial till from County Cork, Ireland and aeolian sediments from Rajasthan, India have also been collected and analysed. A graphical summary of the data is presented and allows for quantitative distinction between samples extracted from different sedimentary environments.

  5. Polygon/Cracked Sedimentary Rock

    Science.gov (United States)

    2004-01-01

    4 December 2004 Exposures of sedimentary rock are quite common on the surface of Mars. Less common, but found in many craters in the regions north and northwest of the giant basin, Hellas, are sedimentary rocks with distinct polygonal cracks in them. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example from the floor of an unnamed crater near 21.0oS, 311.9oW. Such cracks might have formed by desiccation as an ancient lake dried up, or they might be related to ground ice freeze/thaw cycles or some other stresses placed on the original sediment or the rock after it became lithified. The 300 meter scale bar is about 328 yards long. The scene is illuminated by sunlight from the upper left.

  6. Study of reactive transfer of hydrogen within intact clayrock

    OpenAIRE

    Didier, Mathilde

    2012-01-01

    Hydrogen gas will be produced by anaerobic corrosion of radioactive waste containers in the geological repository. This gas could affect the geological layer (Callovo-Oxfordian) stability, first due to its reductive capacity and then also due to its continuous production for about 100,000 years. The local pressure increase could affect the properties of hydro-gaseous dynamic of hydrogen transfers. The reductive capacity of H2 could change the redox properties of the Callovo-Oxfordian and the ...

  7. Europium migration in argilaceous rocks: On the use of micro Laser-Induced Breakdown Spectroscopy (micro LIBS) as a microanalysis tool

    International Nuclear Information System (INIS)

    Eu migration in a Callovo-Oxfordian argilite sample was studied using the micro LIBS technique. Quantitative elemental mapping were made by micro LIBS that showed the actual distribution of the various micro areas observed on the Callovo-Oxfordian sample's surface. Calcite, dolomite, alumino-silicates, quartz, pyrite and iron oxides were identified and their statistical distribution was determined. Experimental Eu profiles observed are consistent with diffusion process accompanied by heterogeneous sorption on alumino-silicate surface. (author)

  8. Geodynamic evolution of sedimentary basins

    Energy Technology Data Exchange (ETDEWEB)

    Roure, F.; Ellouz, N.; Shein, V.S.; Skvortsov, I.I. [eds.

    1996-12-01

    This volume constitutes the proceedings of a conference held in Moscow in 1992, and organized by the Institut Francais du Petrole (IFP), the IGIRGI and VNIGNI Russian institutes under the auspices of the Russian Ministries of Fuels and Energy, Ecology and Nature. Geological features of the CIS countries, especially Russia, have driven their geologists` interest to specific questions as the petroleum potential of Proterozoic series, the resources located at a depth of 5000 m and more, or the impact of recent deformations on petroleum exploration and production. From the 27 papers of this conference, only 16 were selected which deal with oil and natural gas fields or coal deposits and geologic traps in the extensional and compressional basins of the CIS republics or in their western counterparts, or with physical and numerical structural models and other modeling techniques used for petroleum potential appraisal in sedimentary basins. The other papers deal with thematic aspects of basin formation in general or in specific areas with no reference to hydrocarbon genesis. (J.S.).

  9. Volcanic and sedimentary-rock aquifers

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set represents the extent of the Volcanic and sedimentary-rock aquifers in the states of Montana, Wyoming, Idaho, Nevada, California, Oregon, and...

  10. The White Nile sedimentary system

    Science.gov (United States)

    Garzanti, Eduardo; Andò, Sergio; Padoan, Marta; Resentini, Alberto; Vezzoli, Giovanni; Villa, Igor

    2014-05-01

    The Nile River flows for ~6700 km from south of the Equator to finally reach the Mediterranean Sea at northern subtropical latitudes (Woodward et al. 2007). This is the longest sedimentological laboratory on Earth, a unique setting in which we are investigating changes in sediment composition associated with diverse chemical and physical processes, including weathering and hydraulic sorting. The present study focuses on the southern branch of the Nile across 20° of latitude, from hyperhumid Burundi and Rwanda highlands in central Africa to Khartoum, the capital city of Sudan at the southern edge of the Sahara. Our study of the Kagera basin emphasizes the importance of weathering in soils at the source rather than during stepwise transport, and shows that the transformation of parent rocks into quartzose sand may be completed in one sedimentary cycle (Garzanti et al. 2013a). Micas and heavy minerals, less effectively diluted by recycling than main framework components, offer the best key to identify the original source-rock imprint. The different behaviour of chemical indices such as the CIA (a truer indicator of weathering) and the WIP (markedly affected by quartz dilution) helps us to distinguish strongly weathered first-cycle versus polycyclic quartz sands (Garzanti et al. 2013b). Because sediment is efficiently trapped in East African Rift lakes, the composition of Nile sediments changes repeatedly northwards across Uganda. Downstream of both Lake Kyoga and Lake Albert, quartzose sands are progressively enriched in metamorphiclastic detritus supplied from tributaries draining amphibolite-facies basements. The evolution of White Nile sediments across South Sudan, a scarcely accessible region that suffered decades of civil war, was inferred from the available information (Shukri 1950), integrated by original petrographic, heavy-mineral and geochemical data (Padoan et al. 2011). Mineralogical and isotopic signatures of Bahr-el-Jebel and Sobat sediments, derived

  11. Sedimentary Environments Offshore Norway - Palaeozoic to Recent

    Energy Technology Data Exchange (ETDEWEB)

    Martinsen, Ole J.; Dreyer, Tom [eds.

    1999-07-01

    The report includes the extended abstracts from the conference, 71 in number. The presentations discuss the sedimentary characteristics of the North Sea area and the the methods used in the research, a thorough knowledge of which is important for economic exploration of the oil and gas resources of the North Sea.

  12. Tracing the origin of water and solute transfers in deep groundwater from Oxfordian, Dogger and Trias formations in the east of the Paris Basin - France

    International Nuclear Information System (INIS)

    In order to assess the feasibility for long lived radioactive wastes storage facilities in deep geological formation, solute transport processes must be investigated in the vicinity of the host formation. In France, the Oxfordian and Dogger limestone layers surrounding the Callovo-Oxfordian (COx) argillite in the east of the Paris Basin are investigated for this purpose. More than 60 samples of Oxfordian and Dogger formation groundwater and one sample of Triassic formation groundwater, located at the bottom section of the investigated sedimentary cover, were collected over a 250 km2 area, and were analysed for major ions, δ18O and δ2H of water, 87Sr/86Sr/, and δ34S and δ18O of dissolved sulphate. Oxfordian and Dogger formation water is from meteoric origin, and no direct water flow between Oxfordian, Dogger, nor Triassic formations was evidenced. Mineralization processes of the Dogger limestone groundwater were fully investigated. These processes correspond to a series of geochemical reactions including: calcite dissolution, incongruent dissolution of dolomite, ion addition from upward vertical diffusion through the sedimentary pile inducing cation exchange and further dissolution due to the increased ionic strength of the solutions. A PHREEQC model was developed to simulate inferred chemical processes. The model output is consistent with observed data. (authors)

  13. Epigenetic alterations of sedimentary rocks at deposits

    International Nuclear Information System (INIS)

    Notions are explained, and technique for studying epigenetic alterations of sedimentary rocks at uranium deposits is described. Main types of epigenetic transformations and their mineralogic-geochemical characteristics are considered. Rock alterations, accompanying uranium mineralization, can be related to 2 types: oxidation and reduction. The main mineralogic-geochemical property of oxidation transformations is epigenetic limonitization. Stratal limonitization in primary grey-coloured terrigenic rocks and in epigenetically reduced (pyritized) rocks, as well as in rock, subjected to epigenetic gleying, are characterized. Reduction type of epigenetic transformations is subdivided into sulphidic and non-sulphidic (gley) subtypes. Sulphidic transformations in grey-coloured terrigenic rocks with organic substance of carbonic row, in rocks, containing organic substance of oil row, sulphide transformations of sedimentary rocks, as well as gley transformations, are considered

  14. PREDICTED SEDIMENTARY SECTION OF SUBGLACIAL LAKE VOSTOK

    Directory of Open Access Journals (Sweden)

    G. I. Leychenkov

    2012-01-01

    Full Text Available In early February 2012, the drill hole at the Vostok Station encountered theLakeVostokwater. This step is important to study the lake composition including possible microbial life and to model subglacial environments however, the next ambitious target of the Vostok Drilling Project is sampling of bottom sediments, which contain the unique record of ice sheet evolution and environmental changes in centralAntarcticafor millions of years. In this connection, the forecast of sedimentary succession based on existing geophysical data, study of mineral inclusions in the accretion ice cores and tectonic models is important task. Interpretation of Airborne geophysical data suggests thatLakeVostokis the part of spacious rift system, which exists at least from Cretaceous. Reflection and refraction seismic experiments conducted in the southern part ofLakeVostokshow very thin (200–300 m stratified sedimentary cover overlying crystalline basement with velocity of 6.0–6.2 km/s. At present, deposition in southernLakeVostokis absent and similar conditions occurred likely at least last3 m.y. when ice sheet aboveLakeVostokchanged insignificantly. It can be also inferred that from the Late Miocene the rate of deposition inLakeVostokwas extremely low and so the most of sedimentary section is older being possibly of Oligocene to early to middle Miocene age when ice sheet oscillated and deposition was more vigorous. If so, the sampling of upper few meters of this condensed section is very informative in terms of history of Antarctic glaciation. Small thickness of sedimentary cover raises a question about existence of lake (rift depression during preglacial and early glacial times.

  15. Clay minerals and sedimentary basin history

    OpenAIRE

    Merriman, Richard J.

    2005-01-01

    Clay minerals in the mud and soil that coat the Earth's surface are part of a clay cycle that breaks down and creates rock in the crust. Clays generated by surface weathering and shallow diagenetic processes are transformed into mature clay mineral assemblages in the mudrocks found in sedimentary basins. During metamorphism, the release of alkali elements and boron from clay minerals generates magmas that are subsequently weathered and recycled, representing the magma-to-mud pathway of the cl...

  16. Rapid lithification masks the Venus sedimentary cycle

    Science.gov (United States)

    Ghail, R.

    2015-10-01

    Venera lander data are usually assumed to indicate basaltic lavas but a significant fraction of the rock material must be volatiles, such as sulphur, implying at least strongly weathered basalts. The lander images most closely resemble sedimentary material, with layered strata (which may be pyroclastic in origin)that are sometimes broken into cobbles and fine grained sediment. The Magellan SAR was relatively insensitive to loose fine-grained material under Venus surface conditions but the reprocessed data reveal a range of weathering processes, particularly at higher elevations, and mass wasting of steep slopes. Mean wind speeds are strongly altitude dependent and are able to erode and transport material throughout the highland regions. In some areas, this material is deposited on adjacent plains where, under the extreme Venus surface conditions, lithification is an apparently rapid process. Thus the largely featureless plains may not be igneous at all but sedimentary in origin. The settling out and lithification of sedimentary material is consistent with observed crater degradation, in which low-lying crater floors are infilled first.

  17. Technical Note: n-Alkane lipid biomarkers in loess: post-sedimentary or syn-sedimentary?

    Directory of Open Access Journals (Sweden)

    D. Faust

    2012-07-01

    Full Text Available There is an ongoing discussion whether n-alkane biomarkers – and organic matter (OM from loess in general – reflect a syn-sedimentary paleoenvironmental and paleoclimate signal or whether they are significantly a post-sedimentary feature contaminated by root-derived OM. We present first radiocarbon data for the n-alkane fraction of lipid extracts and for the first time luminescence ages for the Middle to Late Weichselian loess-paleosol sequence of Gleina in Saxony, Germany. Comparison of these biomarker ages with sedimentation ages as assessed by optically stimulated luminescence (OSL dating shows that one n-alkane sample features a syn-sedimentary age (14C: 29.2 ± 1.4 kyr cal BP versus OSL: 27.3 ± 3.0 kyr. By contrast, the 14C ages derived from the other n-alkane samples are clearly younger (20.3 ± 0.7 kyr cal BP, 22.1 ± 0.7 kyr cal BP and 29.8 ± 1.4 kyr cal BP than the corresponding OSL ages (26.6 ± 3.1 kyr, 32.0 ± 3.5 kyr and 45.6 ± 5.3 kyr. This finding suggests that a post-sedimentary n-alkane contamination presumably by roots has occurred. In order to estimate the post-sedimentary n-alkane contamination more quantitatively, we applied a 14C mass balance calculation based on the measured pMC (percent modern carbon values, the calculated syn-sedimentary pMC values and pMC values suspected to reflect likely time points of post-sedimentary contamination (current, modern, 3 kyr, 6 kyr and 9 kyr. Accordingly, current and modern root-contamination would account for up to 7%, a 3 kyr old root-contamination for up to 10%, and an Early and Middle Holocene root-contamination for up to 20% of the total sedimentary n-alkane pool. We acknowledge and encourage that these first radiocarbon results need further confirmation both from other loess-paleosol sequences and for different biomarkers, e.g. carboxylic acids or alcohols as further lipid biomarkers.

  18. Investigation on geological environments (IGE)

    International Nuclear Information System (INIS)

    This session gathers 9 articles (posters) dealing with: (S, O, Sr) isotopic constraints on the diagenetic evolution of the Callovo-Oxfordian formation at the Meuse/Haute-Marne URL; the scale effect and heterogeneity of hydraulic conductivity of sedimentary rocks at Horonobe URL site; the investigation and modeling of 3D distribution of water chemistries in Horonobe, Hokkaido, Japan; PH4: a 250 m deep borehole in Tournemire for assessing the contribution of transport phenomena to assumed overpressures in the Toarcian/Domerian semipermeable; the lateral variability of mineralogy and pore water chemistry of the Boom Clay; 36Cl in groundwaters of Oxfordian and Dogger limestones of the Eastern Paris basin: implications for old groundwater dating; the statistical preprocessing and analyses of hydro-geo-meteorologic time series in the PP experiment of Mont Terri (method. and first results); the hydraulic conductivity of the Boom Clay in north-east Belgium based on four core-drilled boreholes; and a new approach of laboratory permeability measurement of very tight rocks: experimental data of BCF, Mecsek Mts, SW Hungary

  19. Quantitative compositional analysis of sedimentary materials using thermal emission spectroscopy: 1. Application to sedimentary rocks

    Science.gov (United States)

    Thorpe, Michael T.; Rogers, A. Deanne; Bristow, Thomas F.; Pan, Cong

    2015-11-01

    Thermal emission spectroscopy is used to determine the mineralogy of sandstone and mudstone rocks as part of an investigation of linear spectral mixing between sedimentary constituent phases. With widespread occurrences of sedimentary rocks on the surface of Mars, critical examination of the accuracy associated with quantitative models of mineral abundances derived from thermal emission spectra of sedimentary materials is necessary. Although thermal emission spectroscopy has been previously proven to be a viable technique to obtain quantitative mineralogy from igneous and metamorphic materials, sedimentary rocks, with natural variation of composition, compaction, and grain size, have yet to be examined. In this work, we present an analysis of the thermal emission spectral (~270-1650 cm-1) characteristics of a suite of 13 sandstones and 14 mudstones. X-ray diffraction and traditional point counting procedures were all evaluated in comparison with thermal emission spectroscopy. Results from this work are consistent with previous thermal emission spectroscopy studies and indicate that bulk rock mineral abundances can be estimated within 11.2% for detrital grains (i.e., quartz and feldspars) and 14.8% for all other mineral phases present in both sandstones and mudstones, in comparison to common in situ techniques used for determining bulk rock composition. Clay-sized to fine silt-sized grained phase identification is less accurate, with differences from the known ranging from ~5 to 24% on average. Nevertheless, linear least squares modeling of thermal emission spectra is an advantageous technique for determining abundances of detrital grains and sedimentary matrix and for providing a rapid classification of clastic rocks.

  20. Deciphering sedimentary recycling via multiproxy in situ analyses

    OpenAIRE

    Lancaster, Penelope J.; Tyrrell, Shane; Daly, J. Stephen; Storey, Craig D.

    2013-01-01

    Sedimentary rocks and modern sediments sample large volumes of the Earth’s crust, and pre-serve units that vary greatly in age and composition. Determining the provenance of component minerals is complicated by the ability of some minerals to be recycled through multiple sedimentary cycles, so minerals from completely unrelated sources may end up in the same sedimentary basin. To untangle these multi-stage signals, two or more chemical signatures measured in minerals with different stability ...

  1. Incidences of polluting episodes in sedimentary media

    International Nuclear Information System (INIS)

    There exist diverse radioactivity sources in the environment coming from anthropogenic activities that alter the natural levels of radiation. The detailed study of the environmental impact of these sources is of great interest, because it provides knowledge for subsequent decontamination works and environmental control. In this work, it is analyzed the radioactive contamination caused by the radionuclide 226Ra in sedimentary media under a liquid sheet. In this way, the dumping of the radionuclide in sediment columns has been studied in laboratory, determining how its penetration in depth develops along time and for different grain sizes. For this purpose, a migration model based on the numeric resolution of the diffusion equation has been devised.

  2. Sedimentary response to ocean gateway circulation changes

    Science.gov (United States)

    Heinze, Christoph; Crowley, Thomas J.

    1997-12-01

    Previous modeling studies suggested that changes in ocean gateways may have exerted a dramatic influence on the ocean circulation. In this pilot study we extend those results to examining the potential ramifications of circulation changes on the sedimentary record. A version of the Hamburg carbon cycle/sediment model is used in these sensitivity experiments. Results indicate that internal reorganization of the ocean circulation can potentially cause very large regional changes in lysocline depth (1500-3000 m) and opal deposition. These shifts are sometimes comparable in magnitude to those imposed by changes in external forcing (e.g., climate, sea level, and weathering). Comparisons of the model response with the geologic record indicate some significant levels of first-order agreement. This exercise suggests that opportunities now exist for physically based modeling of past sediment responses to circulation and climate changes.

  3. Sedimentary remagnetizations involving pyrrhotite and greigite (Invited)

    Science.gov (United States)

    Roberts, A. P.

    2013-12-01

    Late diagenetic growth of the ferrimagnetic iron sulfide minerals, monoclinic pyrrhotite and greigite, will give rise to remagnetizations of their host sediments. Sedimentary pyrrhotite formation has been the subject of much confusion in the paleomagnetic literature. Its growth is kinetically limited. Authigenic monoclinic pyrrhotite has, therefore, not been reported in modern sediments. If monoclinic pyrrhotite is present in modern sediments, it is likely to have a detrital origin, as has been demonstrated in marginal basins adjacent to denuding regional metamorphic orogenic belts. If authigenic monoclinic pyrrhotite occurs in sediments, it will carry a magnetization that was acquired much later than deposition. Identification of authigenic pyrrhotite should, therefore, lead an investigator to suspect that the sediment has been at least partially remagnetized. Iron sulfides have high electron backscatter and are easily investigated using electron microscopy. Microtextural observations of sedimentary pyrrhotite can often provide direct confirmation that the pyrrhotite formed during later diagenetic reactions (e.g., after sediment compaction). Greigite can also give rise to remagnetizations, but, unlike pyrrhotite, it can grow quickly, even within an anoxic water column before deposition. Multiple generations of greigite can also form even during early diagenesis. These possibilities make it more difficult to use electron microscopic observations to detect remagnetization mechanisms, although microtextural relationships with other minerals can still provide strong direct evidence for remagnetization. For both pyrrhotite and greigite, remagnetizations are generally detected using conventional paleomagnetic observations. These include detection of magnetic polarities that contradict those carried by coexisting detrital magnetic minerals and failure of paleomagnetic field tests (mainly the fold and reversal tests). An overview of the features associated with

  4. Tectonics and Sedimentary Basins of the South China Sea: Challenges and Progresses

    Institute of Scientific and Technical Information of China (English)

    Zhou Di; Yao Bochu

    2009-01-01

    @@ The special issue "Tectonics and Sedimentary Basins of the South China Sea" consists of 19 articles arranged in the order of deep structure,general tectonics,tectonic modeling,and sedimentary basins especially the deepwater sedimentary basins.

  5. Microbial shaping of sedimentary wrinkle structures

    Science.gov (United States)

    Mariotti, G.; Pruss, S. B.; Perron, J. T.; Bosak, T.

    2014-10-01

    Wrinkle structures on sandy bed surfaces were present in some of the earliest sedimentary environments, but are rare in modern environments. These enigmatic millimetre- to centimetre-scale ridges or pits are particularly common in sediments that harbour trace fossils and imprints of early animals, and appeared in the aftermath of some large mass extinctions. Wrinkle structures have been interpreted as possible remnants of microbial mats, but the formation mechanism and associated palaeoenvironmental and palaeoecological implications of these structures remain debated. Here we show that microbial aggregates can form wrinkle structures on a bed of bare sand in wave tank experiments. Waves with a small orbital amplitude at the bed surface do not move sand grains directly. However, they move millimetre-size, light microbial fragments and thereby produce linear sand ridges and rounded scour pits at the wavelengths observed in nature within hours. We conclude that wrinkle structures are morphological biosignatures that form at the sediment-water interface in wave-dominated environments, and not beneath microbial mats as previously thought. During early animal evolution, grazing by eukaryotic organisms may have temporarily increased the abundance of microbial fragments and thus the production of wrinkle structures.

  6. Investigating Coccolithophorid Biology in the Sedimentary Laboratory

    Science.gov (United States)

    McClelland, H. L. O.; Barbarin, N.; Beaufort, L.; Hermoso, M.; Rickaby, R. E. M.

    2014-12-01

    Coccolithophores are the ocean's dominant calcifying phytoplankton; they play an important, but poorly understood, role in long-term biogeochemical climatic feedbacks. Calcite producing marine organisms are likely to calcify less in a future world where higher carbon dioxide concentrations will lead to ocean acidification (OA), but coccolithophores may be the exception. In coccolithophores calcification occurs in an intracellular vesicle, where the site of calcite precipitation is buffered from the external environment and is subject to a uniquely high degree of biological control. Culture manipulation experiments mimicking the effects of OA in the laboratory have yielded empirical evidence for phenotypic plasticity, competition and evolutionary adaptation in asexual populations. However, the extent to which these results are representative of natural populations, and of the response over timescales of greater than a few hundred generations, is unclear. Here we describe a new sediment-based proxy for the PIC:POC (particulate inorganic to particulate organic carbon ratio) of coccolithophore biomass, which is equivalent to the fractional energy contribution to calcification at constant pH, and a biologically meaningful measure of the organism's tendency to calcify. Employing the geological record as a laboratory, we apply this proxy to sedimentary material from the southern Pacific Ocean to investigate the integrated response of real ancient coccolithophore populations to environmental change over many thousands of years. Our results provide a new perspective on phenotypic change in real populations of coccolithophorid algae over long timescales.

  7. Sedimentary environment indicators: Benzothiazole and its derivatives

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Benzothiazoles distributional characteristics of crude oils and non-hydrocarbon fractions of source rocks in Mangya depression of the Qaidam Basin, Lunnan oil field in the Tarim Basin, Kelamayi oil field in the Junggar Basin and the Tulufan Basin oil field were analyzed. It was found that the distributions of benzothiazole are remarkable diversity in different sedimentary environmental oils. The swamp crude oils contain high quantity of benzothiazole and relatively high quantity of alkylthio-benzothiazole and 2(3H)-benzothiazolone. But the quantity of the 2,2′-dithiobis- ben-zothiazole is relatively low. The abundance of benzothiazole and 2,2′-dithiobis-benzothiazole are relatively high in semi-brackish water lacustrine crude oils, but the quantity of alkylthio-benzothiazole and 2(3H)-benzothiazolone are rela-tively low. The benzothiazoles belong to weak acid and mild base compound, and their stabilization conditions relate to their environmental medium. The nitrogenous bases are in favor of alkalescence environment, while weak acid nitroge-nous compounds are the main stable products under the weak acid environment. Benzothiazoles have great signifi-cance in identifying the oil- and gas-formed environment and the geochemistry study of non-hydrocarbon fraction in the future.

  8. Continental Growth and the Sedimentary Record

    Science.gov (United States)

    Dhuime, B.; Hawkesworth, C. J.; Robinson, R. A. J.; Cawood, P. A.

    2014-12-01

    Detrital sedimentary rocks provide average samples of the continental crust formed at different times and in different places. Some materials are more susceptible to erosion and/or to preservation bias than others, and one issue is to understand how the compositions of a range of source rocks are then recorded in the sediments. Here we considered two different approaches to model the growth of the continental crust: (i) The variation of Nd isotopes in continental shales with different deposition ages, which requires a correction of the bias induced by preferential erosion of younger rocks through an erosion parameter usually referred to as 'K'. The determination of K, and the extent to which it varies in different erosion systems, thus have fundamental implications for the models of continental growth based on radiogenic isotopes in continental sediments. (ii) The variations in U-Pb, Hf and O isotopes in detrital zircons, from 'modern' sediments sampled worldwide. In this approach, O isotopes are used to screen 'hybrid' Hf model ages (i.e. ages resulting from mixing processes of crustal material from different ages) from Hf model ages that represent actual crust formation ages. These two approaches independently suggest that the continental crust has been generated continuously, but with a marked decrease in the continental growth rate at ~3 Ga. The >4 Ga to ~3 Ga period is characterised by relatively high net rates of continental growth (~3.0 km3.a-1), which are similar to the rates at which new crust is generated, and destroyed, at the present time. Net growth rates are much lower since 3 Ga (~0.8 km3.a-1), which may be attributed to higher rates of destruction of continental crust. The inflexion in the continental growth curve at ~3 Ga indicates a change in the way the crust was generated and preserved. This change may be linked to onset of subduction-driven plate tectonics and discrete subduction zones.

  9. Mars Sedimentary Geology: Key Concepts and Outstanding Questions

    OpenAIRE

    Grotzinger, John; Beaty, David; Dromart, Gilles; Gupta, Sanjeev; Harris, Mitch; Hurowitz, Joel; Kocurek, Gary; McLennan, Scott; Milliken, Ralph E.; Ori, Gian G.; Sumner, Dawn Y.

    2011-01-01

    Processes that operate at planetary surfaces have the potential to record a history of planetary evolution in the form of sedimentary rocks. This is important because our experience on Earth shows that sediments and sedimentary rocks are the dominant archive of high-resolution proxies of present and past tectonic, climatic, and biological processes. Our understanding of the evolution of Earth’s very ancient climate and paleobiological records derives from detailed exam...

  10. Geophysical methods for the study of sedimentary cycles

    Institute of Scientific and Technical Information of China (English)

    Xu Jingling; Liu Luofu; Wang Guiwen; Shen Jinsong; Zhang Chunhua

    2009-01-01

    We present the wavelet depth-frequency analysis and variable-scale frequency cycle analysis methods to study sedimentary cycles. The spectrum analysis, variable-scale frequency cycle analysis, and wavelet depth-frequency analysis methods are mainly discussed to distinguish sedimentary cycles of different levels. The spectrum analysis method established the relationship between the spectrum characteristics and the thickness and number of sedimentary cycles. Both the variable-scale frequency cycle analysis and the wavelet depth-frequency analysis are based on the wavelet transform. The variable-scale frequency cycle analysis is used to obtain the relationship between the periodic changes of frequency in different scales and sedimentary cycles, and the wavelet depth-frequency analysis is used to obtain the relationship between migration changes of frequency energy clusters and sedimentary cycles. We designed a software system to process actual logging data from the Changqing Oilfieid to analyze the sedimentary cycles, which verified the effectiveness of the three methods, and good results were obtained.

  11. NATURAL GAS RESOURCES IN DEEP SEDIMENTARY BASINS

    Energy Technology Data Exchange (ETDEWEB)

    Thaddeus S. Dyman; Troy Cook; Robert A. Crovelli; Allison A. Henry; Timothy C. Hester; Ronald C. Johnson; Michael D. Lewan; Vito F. Nuccio; James W. Schmoker; Dennis B. Riggin; Christopher J. Schenk

    2002-02-05

    From a geological perspective, deep natural gas resources are generally defined as resources occurring in reservoirs at or below 15,000 feet, whereas ultra-deep gas occurs below 25,000 feet. From an operational point of view, ''deep'' is often thought of in a relative sense based on the geologic and engineering knowledge of gas (and oil) resources in a particular area. Deep gas can be found in either conventionally-trapped or unconventional basin-center accumulations that are essentially large single fields having spatial dimensions often exceeding those of conventional fields. Exploration for deep conventional and unconventional basin-center natural gas resources deserves special attention because these resources are widespread and occur in diverse geologic environments. In 1995, the U.S. Geological Survey estimated that 939 TCF of technically recoverable natural gas remained to be discovered or was part of reserve appreciation from known fields in the onshore areas and State waters of the United. Of this USGS resource, nearly 114 trillion cubic feet (Tcf) of technically-recoverable gas remains to be discovered from deep sedimentary basins. Worldwide estimates of deep gas are also high. The U.S. Geological Survey World Petroleum Assessment 2000 Project recently estimated a world mean undiscovered conventional gas resource outside the U.S. of 844 Tcf below 4.5 km (about 15,000 feet). Less is known about the origins of deep gas than about the origins of gas at shallower depths because fewer wells have been drilled into the deeper portions of many basins. Some of the many factors contributing to the origin of deep gas include the thermal stability of methane, the role of water and non-hydrocarbon gases in natural gas generation, porosity loss with increasing thermal maturity, the kinetics of deep gas generation, thermal cracking of oil to gas, and source rock potential based on thermal maturity and kerogen type. Recent experimental simulations

  12. Archaen to Recent aeolian sand systems and their sedimentary record

    DEFF Research Database (Denmark)

    Rodríguez-López, Juan Pedro; Clemmensen, Lars B; Lancaster, Nick;

    2014-01-01

    behaviour, and therefore cannot be used to consistently account for and predict the nature of the preserved sedimentary record in terms of formative processes. Archean and Neoproterozoic aeolian successions remain poorly constrained. Palaeozoic ergs developed and accumulated in relation to the......–Modern siliciclastic coastal systems. The sedimentary record of most modern aeolian systems remains largely unknown. The majority of palaeoenvironmental reconstructions of aeolian systems envisage transverse dunes, whereas successions representing linear and star dunes remain under-recognized. Research questions that...... primarily known from the Cenozoic. The complexity of aeolian sedimentary processes and facies variability are under-represented and excessively simplified in current facies models, which are not sufficiently refined to reliably account for the complexity inherent in bedform morphology and migratory...

  13. Some characteristics of Hirsizdere sedimentary magnesite deposits, Denizli, SW Turkey

    Science.gov (United States)

    Zedef, Veysel; Russell, Michael

    2016-04-01

    Approximately 8% of Turkey is covered by ultramafic rocks which host economically important deposits of magnesite, chromite and olivine. Magnesite deposits are of three types: (1) Massive or crystalline, (2) Cryptocrystalline and (3) Sedimentary. Cryptocrystalline and sedimentary type magnesite deposits are widespread all over Turkey although the massive type deposits are seemingly absent. In this study, we examined the sedimentary magnesite deposits of Hirsizdere, located in the province of Denizli, SW Turkey. The deposits formed as five beds within an ultramafic environment. The thickness of the magnesite beds can reach up to 4 meters and may be traced up to 3 km from west to east. The deposit comprises half a million tons of magnesite with some associated dolomite.

  14. Geology, exploration status of Uruguay's sedimentary basins

    Energy Technology Data Exchange (ETDEWEB)

    Goso, C.; Santa Ana, H. de (Administracion Nacional de Combustibles, Alcohol y Portland (Uruguay))

    1994-02-07

    This article attempts to present the geological characteristics and tectonic and sedimentary evolution of Uruguayan basins and the extent to which they have been explored. Uruguay is on the Atlantic coast of South America. The country covers about 318,000 sq km, including offshore and onshore territories corresponding to more than 65% of the various sedimentary basins. Four basins underlie the country: the Norte basin, the Santa Lucia basin, the offshore Punta del Este basin, and the offshore-onshore Pelotas-Merin basin. The Norte basin is a Paleozoic basin while the others are Mesozoic basins. Each basin has been explored to a different extent, as this paper explains.

  15. Epigenetic alteration of sedimentary rocks at hydrogenic uranium deposit

    International Nuclear Information System (INIS)

    The author introduces the concept, the recognition criteria, the genesis and classification of the epigenetic alteration of sedimentary rocks in brief, and expounds the mineral-geochemical indications and characteristics of oxidation and reduction alterations in different geochemical zones in detail, and proposes the two models of ore-controlling zonation of epigenetic alteration. The authors finally introduce research methods of epigenetic alteration

  16. Examples of transient sounding from groundwater exploration in sedimentary aquifers

    Science.gov (United States)

    Fitterman, D.V.

    1987-01-01

    Examples of the use of transient electromagnetic soundings for three groundwater exploration problems in sedimentary aquifers are given. The examples include: 1) estimating depths to water table and bedrock in an alluvium-filled basin, 2) mapping a confined freshwater aquifer in bedrock sediments, and 3) locating a freshwater/saltwater interface in a glacial-outwash aquifer. -from Author

  17. Sulfurised carbohydrates: An important sedimentary sink for organic carbon?

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Kok, M.D.; Koster, J.; Schouten, S.

    1998-01-01

    In contrast to the general belief that carbohydrate carbon (CCHO) is preferentially degraded and is not extensively preserved in the sedimentary record, it is shown here that CCHO forms a large fraction of the organic matter (OM) of the total organic carbon (TOC)-rich upper Jurassic Kimmeridge Clay

  18. Isotope studies of dolomite formation under sedimentary conditions

    Science.gov (United States)

    Clayton, R.N.; Jones, B.F.

    1968-01-01

    Measurements of stable isotope abundances of the carbonate portion of the sediment in Deep Springs Lake, California, indicate the presence of at least three phases: a magnesian calcite, a primary sedimentary dolomite, and a detrital dolomite. The former two have isotopic compositions consistent with precipitation at isotopic equilibrium from waters of the lake area. The measured isotopic fractionation factor between sedimentary dolomite and its interstitial water is 1.0351, which is outside the range possible for calcite-water. This indicates that the dolomite has formed by direct crystallization from solution and not from a caloite precursor without further isotope exchange. Isotopic and X-ray evidence does not support the contention of Peterson et al. (1966) that Deep Springs Lake dolomite crystals grow by means of a calcite-like surface layer. ?? 1968.

  19. Sedimentary characteristics of cretaceous in northwestern Ordos basin

    International Nuclear Information System (INIS)

    Based on the integration of previous research achievements and combined with results of field geological investigation, and analysis and determination of samples, as well as the indoor comprehensive study, the paleoclimate characteristics, indications of sedimentary facies, the direction of paleocurrent and the provenance, as well as sedimentary facies and depositional systems of Zhidan Group, Lower Cretaceous in northwestern Ordos basin are systematically analyzed in the framework of the basin evolution. Authors come to a conclusion that sediments of Zhidan Group are mainly of lacustrine and fluvial facies. On the above basis types and features of sand bodies developed in Zhidan Group, Lower Cretaceous are summarized and the potential of uranium ore-formation in different types of sand bodies is discussed.Finally, deltasand bodies of Huachi-Huanhe Formation are thought to be favorable for the formation of sandstone type uranihm deposits. (authors)

  20. Wave tectono-sedimentary processes in Tarim basin

    Institute of Scientific and Technical Information of China (English)

    JIN Zhijun; ZHANG Yiwei; CHEN Shuping

    2005-01-01

    Based on the unconformities, the formation times of structures, and geological wave filtering applied to basin fills of typical wells around the Manjiaer area in the Tarim basin, the wave tectono-sedimentary processes in the Tarim Basin are discussed. The results of geological wave filtering of basin fills of typical wells show that, in time domain, the evolution of the Tarim basin was controlled by various wave processes with the periods of 740±Ma, 200±Ma, 100±Ma and 30±Ma. The analyses of basin fills, basin subsidence and unconformities show that the trends of the sedimentary facies belts, depocenters, and centers of subsidence migrated and interchanged periodically with periods of 200±Ma. These show the propagation of wave movements in space domain. The wave evolution of the Tarim basin is of significance to understanding the formation of the oil and gas reservoirs in the basin.

  1. Estimation of sedimentary proxy records together with associated uncertainty

    OpenAIRE

    Goswami, B.; Heitzig, J.; Rehfeld, K.; Marwan, N.; A Ambili; Prasad, S.; Kurths, J.

    2014-01-01

    Sedimentary proxy records constitute a significant portion of the recorded evidence that allow us to investigate paleoclimatic conditions and variability. However, uncertainties in the dating of proxy archives limit our ability to fix the timing of past events and interpret proxy record inter-comparisons. While there are various age-modeling approaches to improve the estimation of the age-depth relations of archives, relatively less focus ...

  2. Estimation of sedimentary proxy records together with associated uncertainty

    OpenAIRE

    Goswami, B.; Heitzig, J.; Rehfeld, K.; Marwan, N.; Anoop, A.; Prasad, S.; Kurths, J.

    2014-01-01

    Sedimentary proxy records constitute a significant portion of the recorded evidence that allows us to investigate paleoclimatic conditions and variability. However, uncertainties in the dating of proxy archives limit our ability to fix the timing of past events and interpret proxy record intercomparisons. While there are various age-modeling approaches to improve the estimation of the age–depth relations of archives, relatively little focus has been placed on the propagation...

  3. Tectonics and sedimentary process in the continental talud in Uruguay

    International Nuclear Information System (INIS)

    The morphology and evolution of the continental margin of Uruguay is due to the interaction of an important set of sedimentary processes. The contourite and turbiditic are the most significant processes which are associated with the development of submarine canyons as well as the gravitational mass respect to major landslides. These processes generate erosional and depositional features with a direct impact on different areas of application, which have potential environmental risks (gravitational landslides, earthquakes, tsunamis) and potential economic resources

  4. Properties of Pliocene sedimentary geomagnetic reversal records from the Mediterranean

    OpenAIRE

    Linssen, J.H.

    1991-01-01

    In the history of the Earth the dipolar geomagnetic field has frequently reversed polarity. Though this property was already known early this century (Brunhes, 1906), nowadays the characteristics and the origin of polarity transitions are still largely unknown. The geomagnetic field and its variations are recorded in rocks as a natural remanent magnetization (NRM) during the formation of these rocks. The study of the NRM in sedimentary reversal records is the subject of this dissertation.

  5. Manganese mineralogy and diagenesis in the sedimentary rock record

    OpenAIRE

    Johnson, Jena E.; Webb, Samuel M.; Ma, Chi; Fischer, Woodward W.

    2016-01-01

    Oxidation of manganese(II) to manganese(III,IV) demands oxidants with very high redox potentials; consequently, manganese oxides are both excellent proxies for molecular oxygen and highly favorable electron acceptors when oxygen is absent. The first of these features results in manganese-enriched sedimentary rocks (manganese deposits, commonly Mn ore deposits), which generally correspond to the availability of molecular oxygen in Earth surface environments. And yet because manganese reduction...

  6. Sedimentary Petrology: from Sorby to the globalization of Sedimentary Geology; La Petrologia Sedimentaria: desde Sorby a la globalizacion de la Geologia Sedimentaria

    Energy Technology Data Exchange (ETDEWEB)

    Alonso-Zarza, A. M.

    2013-02-01

    We describe here the most important milestones and contributions to Sedimentary Petrology compared to other geological disciplines. We define the main aim of our study and the scientific and economic interests involved in Sedimentary Petrology. The body of the paper focuses upon the historical development of this discipline from Henry Sorby's initial work until the present day. The major milestones in its history include: 1) initial descriptive works; 2) experimental studies; 3) the establishment of the different classifications of sedimentary rocks; 4) studies into facies and sedimentary environments; 5) advances in the study of diagenetic processes and their role in hydrocarbon prospection; and 6) the development of Sedimentary Geochemistry. Relationships and coincidences with Sedimentology are discussed. We go on to look at the advances that have taken place over the last 30 years, in which the study of sedimentary rocks is necessarily included in the wider field of Sedimentary Geology as a logical result of the proposal of global models of a changing Earth in which Sedimentary Geology plays a significant part. Finally we mention the notable contributions of Spanish sedimentary petrologists to this whole field of science. (Author) 120 refs.

  7. DOE workshop: Sedimentary systems, aqueous and organic geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    1993-07-01

    A DOE workshop on sedimentary systems, aqueous and organic geochemistry was held July 15-16, 1993 at Lawrence Berkeley Laboratory. Papers were organized into several sections: Fundamental Properties, containing papers on the thermodynamics of brines, minerals and aqueous electrolyte solutions; Geochemical Transport, covering 3-D imaging of drill core samples, hydrothermal geochemistry, chemical interactions in hydrocarbon reservoirs, fluid flow model application, among others; Rock-Water Interactions, with presentations on stable isotope systematics of fluid/rock interaction, fluid flow and petotectonic evolution, grain boundary transport, sulfur incorporation, tracers in geologic reservoirs, geothermal controls on oil-reservoir evolution, and mineral hydrolysis kinetics; Organic Geochemistry covered new methods for constraining time of hydrocarbon migration, kinetic models of petroleum formation, mudstones in burial diagenesis, compound-specific carbon isotope analysis of petroleums, stability of natural gas, sulfur in sedimentary organic matter, organic geochemistry of deep ocean sediments, direct speciation of metal by optical spectroscopies; and lastly, Sedimentary Systems, covering sequence stratigraphy, seismic reflectors and diagenetic changes in carbonates, geochemistry and origin of regional dolomites, and evidence of large comet or asteroid impacts at extinction boundaries.

  8. Application of magnetic susceptibility on palaeozoic sedimentary rocks

    International Nuclear Information System (INIS)

    Complete text of publication follows. Magnetic susceptibility (MS) records from Holocene, Pleistocene and Tertiary sedimentary successions have been widely used as palaeoclimatic proxies. The use of MS in Palaeozoic sediments is becoming more common but still suffers from some controversy. One of the problems is the origin of the magnetic minerals. Most sedimentologists accept the hypothesis that magnetic minerals reflect lithogenic inputs. However, it remains unclear if these inputs are of fluvial or of aeolian nature and if they are influenced by climatic, sea-level or tectonic changes, which act probably at different time-scales. In order to differentiate between different impacts, a strong interdisciplinary characterisation of facies, cyclostratigraphy and the MS signal and MS carriers is required. Furthermore, concerning of Palaeozoic rocks, the influence of diagenesis on the magnetic mineralogy has to be assessed. We would like to promote the interdisciplinary IGCP-project 850, recently funded by the UNESCO, in order to invite collaborators to possibly join our research. The project aims at compiling published magnetic susceptibility records from Palaeozoic sedimentary rocks and at acquiring new data for testing the correlation between susceptibility and sedimentological parameters. Another goal is to investigate the cause of the magnetic susceptibility signal in different sedimentary environments and its relationship to climate controlled environmental parameters. Finally, magnetic susceptibility records from different globally distributed sites will be correlated for reconstructions of past climatic variations.

  9. DOE workshop: Sedimentary systems, aqueous and organic geochemistry

    International Nuclear Information System (INIS)

    A DOE workshop on sedimentary systems, aqueous and organic geochemistry was held July 15-16, 1993 at Lawrence Berkeley Laboratory. Papers were organized into several sections: Fundamental Properties, containing papers on the thermodynamics of brines, minerals and aqueous electrolyte solutions; Geochemical Transport, covering 3-D imaging of drill core samples, hydrothermal geochemistry, chemical interactions in hydrocarbon reservoirs, fluid flow model application, among others; Rock-Water Interactions, with presentations on stable isotope systematics of fluid/rock interaction, fluid flow and petotectonic evolution, grain boundary transport, sulfur incorporation, tracers in geologic reservoirs, geothermal controls on oil-reservoir evolution, and mineral hydrolysis kinetics; Organic Geochemistry covered new methods for constraining time of hydrocarbon migration, kinetic models of petroleum formation, mudstones in burial diagenesis, compound-specific carbon isotope analysis of petroleums, stability of natural gas, sulfur in sedimentary organic matter, organic geochemistry of deep ocean sediments, direct speciation of metal by optical spectroscopies; and lastly, Sedimentary Systems, covering sequence stratigraphy, seismic reflectors and diagenetic changes in carbonates, geochemistry and origin of regional dolomites, and evidence of large comet or asteroid impacts at extinction boundaries

  10. Sequence associations of sedimentary facies in continental basins and their applications to palaeogeographic mapping

    Institute of Scientific and Technical Information of China (English)

    TANG Hua-feng; CHENG Ri-hui; KONG Qing-ying; BAI Yun-feng; YU Ming-feng

    2004-01-01

    According to the characteristics of sedimentary facies and their vertical associations, sequence association of sedimentary facies can be divided into 2 types and 28 subtypes. The first type (type A) is a sedimentary sequence without volcanic rocks, including 18 subtypes. The second type (type B) is a volcanogenic succession including 10 subtypes.Each subtype may reflect certain filling condition under certain sedimentary environment. Time and space distribution of different types of sequence associations can reflect tectonics that controlled the basin evolution, sedimentary environments and palaeogeography.

  11. Member 1 of Yongji Formation (Ey1) sedimentary characteristics and its origin analysis in Yitong Graben

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Ey1 has the unique desultory-weak or gap seismic reflection structure as its one of the most important characteristics. It is very important to clarify sedimentary characteristics and its origin for Yitong Graben and its sedimentary facies and tectonic evolution. On the basis of the research of core analyses, well logging data analyses, sedimentary facies analyses and seismic reflection structure analyses, the authors have concluded the sedimentary characteristics of Ey1, and have carried out Ey1 sedimentary environments and its origin. The result shows that Ey1 desultory-weak or gap seismic reflection may be a series of small scale secondary sediment fans superimposition.

  12. Groundwater flows in Meuse/Haute-Marne aquifer system and the importance of the evolution of the geomorphology over the next million of years

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. A clay-stone formation of Callovo-Oxfordian age is found throughout the multilayered sedimentary fill of the Paris Basin. It is considered as a potential host rock for France's high and intermediate-level long-lived radioactive waste. The Callovo-Oxfordian layer is located between an overlying limestone of Oxfordian age and an underlying limestone of Dogger age.. The Meuse/Haute-Marne sector area is located in the East of France, the area includes the Bure investigation site and a domain referred to as the 'transposition zone' selected as a suitable location for France's high- and intermediate-level long-lived radioactive waste The objective of the study was to estimate how the groundwater flow in the Meuse/Haute- Marne aquifer system will change because of the geomorphologic evolution over the next 1 million of years. The future groundwater flows and the future evolution of the vertical hydraulic gradient in the transposition zone are of importance in the performance assessment and the safety analysis of a future repository for radioactive waste. The study is based on numerical modelling and the established model covers the whole of the Paris basin. The studied time period corresponds to 1 million years into the future. The initial geometry of geological layers as well as the conductivity and the porosity of the layers are input data to model, and defined by the single-continuum multi-scale hydrogeological model of the Paris Basin and the Meuse/Haute-Marne Sector area as developed by Andra. A description of the transient geomorphologic evolution was used as input data to the groundwater flow modelling. The description include: (i) The deformation of the geological layers as a result of a non-symmetric tectonic uplift of the Paris basin and (ii) The movement of the topography because of mechanical erosion along valleys, chemical erosion along plateaus and sedimentation along valleys. The modelling of the

  13. Realistic modelling of observed seismic motion in complex sedimentary basins

    International Nuclear Information System (INIS)

    Three applications of a numerical technique are illustrated to model realistically the seismic ground motion for complex two-dimensional structures. First we consider a sedimentary basin in the Friuli region, and we model strong motion records from an aftershock of the 1976 earthquake. Then we simulate the ground motion caused in Rome by the 1915, Fucino (Italy) earthquake, and we compare our modelling with the damage distribution observed in the town. Finally we deal with the interpretation of ground motion recorded in Mexico City, as a consequence of earthquakes in the Mexican subduction zone. The synthetic signals explain the major characteristics (relative amplitudes, spectral amplification, frequency content) of the considered seismograms, and the space distribution of the available macroseismic data. For the sedimentary basin in the Friuli area, parametric studies demonstrate the relevant sensitivity of the computed ground motion to small changes in the subsurface topography of the sedimentary basin, and in the velocity and quality factor of the sediments. The total energy of ground motion, determined from our numerical simulation in Rome, is in very good agreement with the distribution of damage observed during the Fucino earthquake. For epicentral distances in the range 50km-100km, the source location and not only the local soil conditions control the local effects. For Mexico City, the observed ground motion can be explained as resonance effects and as excitation of local surface waves, and the theoretical and the observed maximum spectral amplifications are very similar. In general, our numerical simulations permit the estimate of the maximum and average spectral amplification for specific sites, i.e. are a very powerful tool for accurate micro-zonation. (author). 38 refs, 19 figs, 1 tab

  14. Spatial Distribution of Particles and Cavities in Sedimentary Deposits

    Czech Academy of Sciences Publication Activity Database

    Kulaviak, Lukáš; Růžička, Marek; Drahoš, Jiří; Hladil, Jindřich

    Bratislava: Slovak University of Technology, 2009 - (Markoš, J.), s. 250 ISBN 978-80-227-3072-3. [International Conference of Slovak Society of Chemical Engineering /36./. Tatranské Matliare (SK), 25.05.2009-29.05.2009] R&D Projects: GA ČR GA104/07/1110; GA ČR(CZ) GD104/08/H055; GA AV ČR IAAX00130702 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z30130516 Keywords : sedimentary structures * limestone particles * MATLAB ( Graphic Toolbox) Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  15. Deformation of Ordovician sedimentary rocks, Prague Synform, Barrandian, Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Černý, Jan; Melichar, R.

    Prague : Czech Geological Survey, 2015 - (Hasalová, P.; Lexa, O.; Jeřábek, P.). s. 10-10 ISBN 978-80-7075-880-9. [CETEG 2015. Meeting of the Central European Tectonic Groups /13./. Meeting of the Czech Tectonic Studies Group /20./. 22.04.2015-25.04.2015, Kadaň] Institutional support: RVO:67985831 Keywords : sedimentary rocks * Prague Synform * Ordovician Subject RIV: DB - Geology ; Mineralogy http://petrol.natur.cuni.cz/ceteg/sites/default/files/images/pdf/abstract-volume-CETEG2015_online.pdf

  16. Study on epigenetic alterations of ore-enclosing sedimentary rocks

    International Nuclear Information System (INIS)

    Epigenetic alterations of sedimentary rocks under effect of exogenous undeground waters of various types: near-surface, ground, stratum, and deep circulation waters, are considered. Association to postsedimentary tectonic structures, confinement of neogenesis to areas of high permeability (porous or crack one), geochemical contradictions between mineral neogenis and facial outlook of deposits, noncoincidence of variability gradient of authigenous mineral associations with variability of primary facial signs of deposits, regular position of mineral formations and ore concentrations in epigenetic mineralogo-geochemical zonation are referred to epigenetic criteria. The complex of epigenetic alterations accompanying mineralization is frequently used as a search sign of uranium deposit of a certain type

  17. Sedimentary and tectonic evolution of ancient Lake Ohrid (Macedonia / Albania)

    OpenAIRE

    Lindhorst, Katja; Krastel, Sebastian; Wagner, Bernd

    2010-01-01

    Lake Ohrid (Macedonia / Albania) is probably the oldest lake in Europe (2-5 Ma), and is considered an important sedimentary archive to study the evolution of a graben system over several million years. Multichannel seismic profiles were acquired in 2007 and 2008 showing that the lake can be divided into two main parts, the slope areas and a large, deep central basin. The basin is bordered by the major eastern and western graben fault, additional faults were identifi ed in the northern part...

  18. In situ NMR analysis of fluids contained in sedimentary rock

    Science.gov (United States)

    de Swiet TM; Tomaselli; Hurlimann; Pines

    1998-08-01

    Limitations of resolution and absorption in standard chemical spectroscopic techniques have made it difficult to study fluids in sedimentary rocks. In this paper, we show that a chemical characterization of pore fluids may be obtained in situ by magic angle spinning (MAS) nuclear magnetic resonance (NMR), which is normally used for solid samples. 1H MAS-NMR spectra of water and crude oil in Berea sandstone show sufficient chemical shift resolution for a straightforward determination of the oil/water ratio. Copyright 1998 Academic Press. PMID:9716484

  19. Hydrogeology of exogenic epigenic uranium deposits (sedimentary type) in Uzbekistan

    International Nuclear Information System (INIS)

    Common problems of hydrogeology and geotechnology for uranium deposits (sedimentary type) in the Republic of Uzbekistan are discussed in the paper. Hydrogeology includes studies of texture of water-bearing horizons, occurrences of ore bodies in horizons, hydrochemical survey, hydrodynamics and engineering geology. Features of deposits workable by underground leaching are presented. Such terms as 'water-bearing horizon', 'efficiency', 'water-bearing bed' are explained accounting the results of 30 year investigations conducted during prospecting, designing and exploitation of uranium deposits. Stages of hydrogeological survey are listed and features of each of them are described. Importance of geotechnology for a deposit characterization is shown. (author). 6 refs.; 1 fig.; 1 tab

  20. Sedimentary facies and ecosystems in the Balearic shelf

    Energy Technology Data Exchange (ETDEWEB)

    Fornos, J.J.; Pomar, L.; Rodriguez-Perea, A.

    1988-08-01

    Sediments of the Balearic platform are mainly carbonate with low percentages of terrigenous influx. These influences are located in littoral areas related to rushing streams. Main bioclastic components are red algae, mollusks, foraminifers, and bryozoans. Terrigenous components are mainly calcareous lithoclasts. Productive ecosystems are built by sea grasses of Posidonia oceanica and marl. Less important are coralline Vidalia volubilis, Cymodocea nodosa, Caulerpa prolifera, and several communities of photophile algae. Each of these ecosystems is the origin of their correlated biofacies. These biofacies are medium biogenic sands, algal sands and gravels, muddy sands, and coarse terrigenous sands. Sediment distribution is directly related to ecosystem distribution, which can be matched with depth and energy variables. Hydrodynamic circumstances are revealed by minor sedimentary structures, like wavy and current ripples, or by hectometric sand waves placed south of Minorca Island at a depth of 48 to 68 m. Sedimentary grains are suffering from erosion and boring processes, which are produced mainly by fungi but also by sponges, polychaetes, bryozoans, and mollusks. These bioerosions are sometimes accompanied by mechanical abrasion and less frequently by chemical corrosion, and this is the principal source of carbonate mud that is transferred to the outer shelf.

  1. Sedimentary structures from different proglacial glaciofluvial settings in Lithuania

    Science.gov (United States)

    Šinkūnė, E.; Šinkūnas, E.

    2012-04-01

    Proglacial glaciofluvial sedimentation during old continental glaciations created a wide range of landforms. However, proglacial deposit sequences are not always well expressed in form of typical landforms. In that case, and also when we are dealing with buried deposits, we face difficulties to recognise their origin or conditions of sedimentation. Sediment bedding structures vary considerably depending on the sedimentation conditions; consequently, they are most helpful in this case. The sediment bedding structures were studied in number of proglacial sediment sequences of different origin in Lithuania to gain the most characteristic complexes of sedimentary structures from particular conditions of sedimentation. In order to analyse the successions of bedforms created in different settings of proglacial glaciofluvial sedimentation the sedimentary models for particular sites in sandur, meltwater streamway and glaciofluvial delta were built. Trough, tabular and planar cross bedding and climbing-ripple cross-lamination is characteristic of proglacial glaciofluvial sediment sequences. However, distinct complexes of bedding structures were recognised for specific conditions of sedimentation in particular sites. This study was financed by the Research Council of Lithuania (No. LEK- 03/2010).

  2. Holocene geocentric dipole tilt model constrained by sedimentary paleomagnetic data

    Science.gov (United States)

    Nilsson, Andreas; Snowball, Ian; Muscheler, Raimund; Uvo, Cintia Bertacchi

    2010-08-01

    Paleomagnetic data, although undeniably limited, have been used to constrain complex time-varying geomagnetic field models. Here we present four different versions of a time varying geocentric dipole model for the past approximately 9000 years based on a limited selection of sedimentary paleomagnetic data with good spatial coverage. The robustness of the modeling approach is evaluated using modern magnetic observation station data provided by the World Data Centre for Geomagnetism in Edinburgh and we discuss the magnitude of the error introduced by insufficient data coverage. The prediction in terms of directional variations is tested against paleomagnetic data from 63 different sedimentary sites and compared to results from recently published spherical harmonic geomagnetic field models. We find that the dipole estimate can explain the paleomagnetic data almost as well as the more complicated spherical harmonic models. Specific areas and records are identified where there are significant differences between the performance of the dipole estimate and the spherical harmonic models. Our results suggest that many of the differences between the dipole model predictions and the paleomagnetic data can be related to poor paleomagnetic quality and/or the lack of accurate and precise time control inherent to some of the records. These results agree with Valet et al. (2008) who suggested that the CALS7K.2 model probably underestimates the dipole contribution in order to reduce the misfit between the inversion and the data. We conclude that better paleomagnetic data and associated time control are needed to improve global geomagnetic field models.

  3. Manganese mineralogy and diagenesis in the sedimentary rock record

    Science.gov (United States)

    Johnson, Jena E.; Webb, Samuel M.; Ma, Chi; Fischer, Woodward W.

    2016-01-01

    Oxidation of manganese (II) to manganese (III,IV) demands oxidants with very high redox potentials; consequently, manganese oxides are both excellent proxies for molecular oxygen and highly favorable electron acceptors when oxygen is absent. The first of these features results in manganese-enriched sedimentary rocks (manganese deposits, commonly Mn ore deposits), which generally correspond to the availability of molecular oxygen in Earth surface environments. And yet because manganese reduction is promoted by a variety of chemical species, these ancient manganese deposits are often significantly more reduced than modern environmental manganese-rich sediments. We document the impacts of manganese reduction and the mineral phases that form stable manganese deposits from seven sedimentary examples spanning from modern surface environments to rocks over 2 billion years old. Integrating redox and coordination information from synchrotron X-ray absorption spectroscopy and X-ray microprobe imaging with scanning electron microscopy and energy and wavelength-dispersive spectroscopy, we find that unlike the Mn(IV)-dominated modern manganese deposits, three manganese minerals dominate these representative ancient deposits: kutnohorite (CaMn(CO3)2), rhodochrosite (MnCO3), and braunite (Mn(III)6Mn(II)O8SiO4). Pairing these mineral and textural observations with previous studies of manganese geochemistry, we develop a paragenetic model of post-depositional manganese mineralization with kutnohorite and calcian rhodochrosite as the earliest diagenetic mineral phases, rhodochrosite and braunite forming secondarily, and later alteration forming Mn-silicates.

  4. Radon distribution in groundwater of the Po sedimentary basin (Italy)

    International Nuclear Information System (INIS)

    222Rn in groundwaters from some areas of the Po sedimentary basin characterized by different hydrological conditions has been determined by alpha-ray activity. Aquifers of three different lithological domains have been considered: (a) an Apennine one, mainly sedimentary (Emilia); (b) an Alpine one, predominantly igneous acid-subacid (Lombardy); and (c) another Alpine one, mainly calcareous (Verona plain). In the first two areas, recent continental waters, waters with a long residence in the aquifers (paleowaters) and sodium chloride waters formed by squeezing of underlying marine sediments have been investigated. In the Verona area, thermal waters coming from deep fissured carbonate formations were analyzed. Rn content is significantly different in the various areas (averages: Lombardy plain, 392; Emilia upper plain, 291; Emilia lower plain, 142; sodium chloride waters, 160; paleowaters, 168 pCi/l). For the Verona thermal waters, the Rn values correlate with temperature and geothermal indicators (SiO2, etc). Hydrodynamic parameters within the aquifers seem to control the Rn distribution in groundwaters circulating in unconsolidated sediments. Factors governing the generation of 222Rn in the rock grains as well as parameters and processes contributing to its transport into the circulating fluids are discussed. Besides known parameters the effect of water molecules, bonded to solid-fluid interfaces on the Rn concentation in the fluids is considered. The release of Rn from these molecules into the circulating fluids is discussed in relation to fluid movement and temperature. (Auth.)

  5. Geochemistry of Fine-grained Sediments and Sedimentary Rocks

    Science.gov (United States)

    Sageman, B. B.; Lyons, T. W.

    2003-12-01

    The nature of detrital sedimentary (siliciclastic) rocks is determined by geological processes that occur in the four main Earth surface environments encountered over the sediment's history from source to final sink: (i) the site of sediment production (provenance), where interactions among bedrock geology, tectonic uplift, and climate control weathering and erosion processes; (ii) the transport path, where the medium of transport, gradient, and distance to the depositional basin may modify the texture and composition of weathered material; (iii) the site of deposition, where a suite of physical, chemical, and biological processes control the nature of sediment accumulation and early burial modification; and (iv) the conditions of later burial, where diagenetic processes may further alter the texture and composition of buried sediments. Many of these geological processes leave characteristic geochemical signatures, making detrital sedimentary rocks one of the most important archives of geochemical data available for reconstructions of ancient Earth surface environments. Although documentation of geochemical data has long been a part of the study of sedimentation (e.g., Twenhofel, 1926, 1950; Pettijohn, 1949; Trask, 1955), the development and application of geochemical methods specific to sedimentary geological problems blossomed in the period following the Second World War ( Degens, 1965; Garrels and Mackenzie, 1971) and culminated in recent years, as reflected by the publication of various texts on marine geochemistry (e.g., Chester, 1990, 2000), biogeochemistry (e.g., Schlesinger, 1991; Libes, 1992), and organic geochemistry (e.g., Tissot and Welte, 1984; Engel and Macko, 1993).Coincident with the growth of these subdisciplines a new focus has emerged in the geological sciences broadly represented under the title of "Earth System Science" (e.g., Kump et al., 1999). Geochemistry has played the central role in this revolution (e.g., Berner, 1980; Garrels and Lerman

  6. The Prediction of Predominant Convection in Sedimentary Basin Systems

    Science.gov (United States)

    Musuuza, J. L.; Radu, F. A.; Attinger, S.

    2012-12-01

    We study a thermohaline system in which the density gradients arise from salinity and temperature differences. Such systems arise in practical applications e.g. geological waste storage and geothermal energy exploitation. A sedimentary-basin set-up is investigated where salinity and temperature increase with depth. In such systems, the buoyancy forces caused by salinity and temperature gradients give rise to counter-acting convection cells. The homogenization theory ideas from Held, Attinnger and Kinzelbach (2005) are applied to the solute and heat transport equations and the two resulting cell problems solved with the coupling between the heat and solute transport preserved. A dimensionless number whose sign changes to negative when thermal-convection is predominant is derived from the solutions to the cell problems in terms of physical variables. The number is tested against numerical simulations performed with the software package d3f on sufficiently refined grids that deliver stable numerical solutions without upwind techniques.

  7. Prediction of thermal conductivity of sedimentary rocks from well logs

    DEFF Research Database (Denmark)

    Fuchs, Sven; Förster, Andrea

    2014-01-01

    The calculation of heat-flow density in boreholes requires reliable values for the change of temperature and rock thermal conductivity with depth. As rock samples for laboratory measurements of thermal conductivity (TC) are usually rare geophysical well logs are used alternatively to determine TC...... major physical parameters (i.e. thermal conductivity, density, hydrogen index, sonic interval transit time, gamma-ray response, photoelectric factor) of artificial mineral assemblages consisting 15 rock-forming minerals that are used in different combinations to typify sedimentary rocks. The predictive...... capacity of the new equations is evaluated on subsurface data from four boreholes drilled into the Mesozoic sequence of the North German Basin, including more than 1700 laboratory-measured thermal-conductivity values. Results are compared with those from other approaches published in the past. The new...

  8. Physicomechanical parameters of sedimentary rocks in eastern Sichuan, China

    International Nuclear Information System (INIS)

    Rock samples were collected and selected from the sedimentary covering strata from Cambrian to Jurassic in eastern Sichuan, China, which belongs to the Upper Yangtze plate. Physicomechanical parameters were measured systematically. Based on parametric texture characteristics and observation data of geology, five regional layer-slip systems are derived. The five layer-slip systems correspond to five reservoir–cover systems, as the incompetent beds correspond to cover beds and the competent beds to reservoir beds. In comparison with the Middle and Lower Yangtze plates, the physicomechanical parameters, lithologic composition and structural characteristics are basically similar to the Upper Yangtze plate. This comparison offers some insight into the oil and gas reservoir–cover systems in the region

  9. Estimation of sedimentary proxy records together with associated uncertainty

    Directory of Open Access Journals (Sweden)

    B. Goswami

    2014-06-01

    Full Text Available Sedimentary proxy records constitute a significant portion of the recorded evidence that allow us to investigate paleoclimatic conditions and variability. However, uncertainties in the dating of proxy archives limit our ability to fix the timing of past events and interpret proxy record inter-comparisons. While there are various age-modeling approaches to improve the estimation of the age-depth relations of archives, relatively less focus has been given to the propagation of the age (and radiocarbon calibration uncertainties into the final proxy record. We present a generic Bayesian framework to estimate proxy records along with their associated uncertainty starting with the radiometric age-depth and proxy-depth measurements, and a radiometric calibration curve if required. We provide analytical expressions for the posterior proxy probability distributions at any given calendar age, from which the expected proxy values and their uncertainty can be estimated. We illustrate our method using two synthetic datasets and then use it to construct the proxy records for groundwater inflow and surface erosion from Lonar lake in central India. Our analysis reveals interrelations between the uncertainty of the proxy record over time and the variance of proxy along the depth of the archive. For the Lonar lake proxies, we show that, rather than the age uncertainties, it is the proxy variance combined with calibration uncertainty that accounts for most of the final uncertainty. We represent the proxy records as probability distributions on a precise, error-free time scale that makes further time series analyses and inter-comparison of proxies relatively simpler and clearer. Our approach provides a coherent understanding of age uncertainties within sedimentary proxy records that involve radiometric dating. It can be potentially used within existing age modeling structures to bring forth a reliable and consistent framework for proxy record estimation.

  10. Holocene Tectonic and Sedimentary Evolution of Coastal San Diego

    Science.gov (United States)

    Maloney, J. M.; Driscoll, N. W.; Brothers, D. S.; Babcock, J. M.; Kent, G.

    2010-12-01

    The shelf and nearshore region of San Diego, California, between La Jolla cove in the north and the U.S.- Mexico border in the south, is an important ecological and economic resource. It contains two of the largest kelp forests in southern California and lies offshore miles of popular beaches. Understanding the interplay between tectonic and sedimentary processes in this area is critical because it will allow us to assess how other forcing functions such as the rapid sea level rise (2 - 3 mm/yr) and predicted climate change associated with global warming are impacting the kelp and nearshore environments. The fault architecture and sedimentary deposits offshore San Diego have been mapped using high-resolution seismic CHIRP profiling. The mapped area lies within the inner California Continental Borderland (CCB), which is characterized by a system of basins and ridges and extensive strike-slip faulting. The CHIRP data clearly images several splays of the Coronado Bank Fault Zone (CBFZ), a major fault in the area, which show recent activity in the upper 30 m of sediment with the most recent deformation at ~4 m below seafloor. Several sediment packages as deep as 50 m below the seafloor are imaged and place important constraints on tectonic deformation and sediment dispersal in the region as well as the earthquake recurrence interval on the CBFZ. Exposed and buried wavecut terraces identified on numerous CHIRP profiles, which can be correlated to terraces mapped regionally, provide insight into tectonic uplift rates and sea-level fluctuations. Finally, the extensive kelp forests offshore Mount Soledad and Point Loma occur where hardgrounds are exposed at the seafloor as a consequence of tectonic uplift. High resolution mapping offshore San Diego is providing new insight into the complex interplay between tectonics, sedimentation, and biology in this ecologically diverse region.

  11. Modeling of the nonlinear resonant response in sedimentary rocks

    Energy Technology Data Exchange (ETDEWEB)

    Ten Cate, James A [Los Alamos National Laboratory; Shankland, Thomas J [Los Alamos National Laboratory; Vakhnenko, Vyacheslav O [NON LANL; Vakhnenko, Oleksiy [NON LANL

    2009-04-03

    We suggest a model for describing a wide class of nonlinear and hysteretic effects in sedimentary rocks at longitudinal bar resonance. In particular, we explain: hysteretic behaviour of a resonance curve on both its upward and downward slopes; linear softening of resonant frequency with increase of driving level; gradual (almost logarithmic) recovery of resonant frequency after large dynamical strains; and temporal relaxation of response amplitude at fixed frequency. Starting with a suggested model, we predict the dynamical realization of end-point memory in resonating bar experiments with a cyclic frequency protocol. These theoretical findings were confirmed experimentally at Los Alamos National Laboratory. Sedimentary rocks, particularly sandstones, are distinguished by their grain structure in which each grain is much harder than the intergrain cementation material. The peculiarities of grain and pore structures give rise to a variety of remarkable nonlinear mechanical properties demonstrated by rocks, both at quasistatic and alternating dynamic loading. Thus, the hysteresis earlier established for the stress-strain relation in samples subjected to quasistatic loading-unloading cycles has also been discovered for the relation between acceleration amplitude and driving frequency in bar-shaped samples subjected to an alternating external drive that is frequency-swept through resonance. At strong drive levels there is an unusual, almost linear decrease of resonant frequency with strain amplitude, and there are long-term relaxation phenomena such as nearly logarithmic recovery (increase) of resonant frequency after the large conditioning drive has been removed. In this report we present a short sketch of a model for explaining numerous experimental observations seen in forced longitudinal oscillations of sandstone bars. According to our theory a broad set of experimental data can be understood as various aspects of the same internally consistent pattern. Furthermore

  12. Potentiality if Rb-Sr method for dating the argillous sedimentary rocks

    International Nuclear Information System (INIS)

    The potentiality of application Rb-Sr method in argillous sediments, using samples from paleozoic and mesozoic formation in brazilian sedimentaries basin was tested. Physical, chemistry and isotopic analysis of thirty eight samples were made in the laboratories of geochronology Research Center from the University of Sao Paulo. Four isochronic diagrams for the argillous sedimentary rocks were also proposed. (author)

  13. Stratigraphic Correlation of Middle Triassic Sequences among Different Paleogeographic Sedimentary Facies in South China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Affected by the Indosinian movement, the sediments in the main part of South China, Yangtzeplatform, started to transform from marine to continental during the Middle Triassic. In the meantime, a noticeable paleogeographic and sedimentary facies differentiation occurred in the marginal regions of the platforms and produced completely different lithologic and paleontologicsequences in various paleogeographic gradients and sedimentary facies areas, which brought about the difficulties for the stratigraphic correlation based on the traditional stratigraphies. This paper proposes to use some characteristic environmental events as the markers of the stratigraphic corre lation across various paleogeographic sedimentary facies, considering that some distinctive regionalenvironmental events should have affected at the same time on the entire basin or the connectedsedimentary regions and produced some closely related sedimentary records in the stratigraphic sequences though the affected intensity and recorded pattern might be different among the regions.The change of violent relative sea level (generally water depth) and the alteration of tectonic activity summarized from the dynamic mechanism of sedimentation are the best markers of environmental events for stratigraphic correlation. Based on the analysis and recognition of some significantenvironmental events at the typical stratigraphic sequences from various paleogeographic sedimentary facies and combined with the consideration of the variations in expressed form and strength fthe events among different paleogeographic gradients and sedimentary facies, the stratigraphic sequences from different sedimentary facies can be easily correlated directly. Furthermore, the evolutionary history of the whole sedimentary basin can be clearly established.

  14. Glacially induced stresses in sedimentary rocks of northern Poland

    Science.gov (United States)

    Trzeciak, Maciej; Dąbrowski, Marcin

    2016-04-01

    During the Pleistocene large continental ice sheets developed in Scandinavia and North America. Ice-loading caused bending of the lithosphere and outward flow in the mantle. Glacial loading is one of the most prominent tectono-mechanical event in the geological history of northern Poland. The Pomeranian region was subjected several times to a load equivalent of more than 1 km of rocks, which led to severe increase in both vertical and horizontal stresses in the upper crustal rocks. During deglaciation a rapid decrease in vertical stress is observed, which leads to destabilization of the crust - most recent postglacial faults scarps in northern Sweden indicate glacially induced earthquakes of magnitude ~Mw8. The presence of the ice-sheet altered as well the near-surface thermal structure - thermal gradient inversion is still observable in NW Poland. The glacially related processes might have left an important mark in the sedimentary cover of northern Poland, especially with regard to fracture reopening, changes in stress state, and damage development. In the present study, we model lithospheric bending caused by glacial load, but our point of interest lies in the overlying sediments. Typical glacial isostatic studies model the response of (visco-) elastic lithosphere over viscoelastic or viscous asthenosphere subjected to external loads. In our model, we introduce viscoelastic sedimentary layers at the top of this stack and examine the stress relaxation patterns therein. As a case study for our modelling, we used geological profiles from northern Poland, near locality of Wejherowo, which are considered to have unconventional gas potential. The Paleozoic profile of this area is dominated by almost 1 km thick Silurian-Ordovician shale deposits, which are interbedded with thin and strong limestone layers. This sequence is underlain by Cambrian shales and sandstones, and finally at ~3 km depth - Precambrian crystalline rocks. Above the Silurian there are approximately

  15. Organic chemical and biomarker analyses of terrestrial archives - is all what we measure of sedimentary origin?

    Science.gov (United States)

    Wiesenberg, G. L.; Gocke, M.

    2012-12-01

    Organic chemical analyses of sedimentary organic matter have been widely used in the past. In terrestrial archives total carbon, organic carbon (Corg) and carbonatic carbon (Ccarb) and their stable isotope composition (δ13C) were established for source assessment of sedimentary matter covering source area (Ccarb) and source vegetation (Corg). Furthermore, radiocarbon dating (Δ14C) was found useful to date sedimentary archives covering the past 50 ka. In addition, the application of biomarkers was tried in sedimentary archives like loess-paleosol sequences to trace source vegetation in more detail. Among others, several alkane molecular proxies have been introduced and adopted in order to assess the contribution of tree and grass vegetation to sedimentary organic matter. Furthermore, other biomarkers like alcohols, fatty acids and others were introduced into the investigation of terrestrial archives. However, studies of the recent 10 years clearly indicate that overprint of sedimentary matter is very likely for terrestrial archives and that caution should be paid, when interpreting chemical results. While secondary carbonate formation is a well known feature covering e.g. loess dolls, pseudomycelia and rhizoliths, commonly these features are not mentioned correctly in a paleoenvironmental context. Nevertheless, they provide unique opportunities for the reassessment of potential contamination of sedimentary organic matter. Especially rhizoliths as calcified root remains can impressively cut vertically through several pairs of sediments and paleosols. While some authors still suggest their formation during sedimentation, we could clearly show different ages of sediments and rhizoliths from the same depth. While some of these root features are easy to see during field campaigns, others are not. This is e.g. observed for biopores in the vicinity of rhizoliths. They can have diameters >5 m and thus can influence sedimentary organic matter in different paleosol

  16. Land subsidence and hydrodynamic compaction of sedimentary basins

    Directory of Open Access Journals (Sweden)

    H. Kooi

    1998-01-01

    Full Text Available A one-dimensional model is used to investigate the relationship between land subsidence and compaction of basin sediments in response to sediment loading. Analysis of the model equations and numerical experiments demonstrate quasi-linear systems behaviour and show that rates of land subsidence due to compaction: (i can attain a significant fraction (>40% of the long-term sedimentation rate; (ii are hydrodynamically delayed with respect to sediment loading. The delay is controlled by a compaction response time τc that can reach values of 10-5-107 yr for thick shale sequences. Both the behaviour of single sediment layers and multiple-layer systems are analysed. Subsequently the model is applied to the coastal area of the Netherlands to illustrate that lateral variability in compaction-derived land subsidence in sedimentary basins largely reflects the spatial variability in both sediment loading and compaction response time. Typical rates of compaction-derived subsidence predicted by the model are of the order of 0.1 mm/yr but may reach values in excess of 1 mm/yr under favourable conditions.

  17. Identifying Historical Occurrences of HABs Using Sedimentary Algal Pigments

    Science.gov (United States)

    Smoak, J. M.; Waters, M. N.

    2008-12-01

    Algal blooms are a common feature of many coastal areas. Under some environmental conditions, these develop into Harmful Algal Blooms (HABs) and present an environmental hazard and a health risk for humans and wildlife due to toxin production. While monitoring programs track the development of contemporary HABs, data are lacking for historical blooms. We use sedimentary algal pigments to identify the occurrence of Karenia Brevis (Florida Red Tide) in sediment cores collected from mangrove environments along the west coast of Florida. Karenia Brevis has a unique pigment, gyroxanthin-diester, that is routinely used to identify red tide in the water column. Gyroxanthin-diester and other carotenoid pigments associated with red tide taxa are analyzed using HPLC techniques. Identification of gyroxanthan-diester is based on comparison with HPLC analysis of gyroxanthin standard, a monoculture sample of K. Brevis and with published spectra of Gyroxanthin-diester in water samples. We track the timing of the K. Brevis using Pb-210 dating models which allows an examination over the last 100 years.

  18. Predicting permeability and electrical conductivity of sedimentary rocks from microgeometry

    International Nuclear Information System (INIS)

    The determination of hydrologic parameters that characterize fluid flow through rock masses on a large scale (e.g., hydraulic conductivity, capillary pressure, and relative permeability) is crucial to activities such as the planning and control of enhanced oil recovery operations, and the design of nuclear waste repositories. Hydraulic permeability and electrical conductivity of sedimentary rocks are predicted from the microscopic geometry of the pore space. The cross-sectional areas and perimeters of the individual pores are estimated from two-dimensional scanning electron micrographs of rock sections. The hydraulic and electrical conductivities of the individual pores are determined from these geometrical parameters, using Darcy's law and Ohm's law. Account is taken of the fact that the cross-sections are randomly oriented with respect to the channel axes, and for possible variation of cross-sectional area along the length of the pores. The effective medium theory from solid-state physics is then used to determine an effective average conductance of each pore. Finally, the pores are assumed to be arranged on a cubic lattice, which allows the calculation of overall macroscopic values for the permeability and the electrical conductivity. Preliminary results using Berea, Boise, Massilon and Saint-Gilles sandstones show reasonably close agreement between the predicted and measured transport properties. 12 refs., 5 figs., 1 tab

  19. Sedimentary input of trace metals from the Chukchi Shelf

    Science.gov (United States)

    Aguilar-Islas, A. M.; Seguré, M.; Rember, R.; Nishino, S.

    2014-12-01

    The distribution of trace metals in the Arctic Ocean has implications for their global cycles, yet until recently few trace metal observations were available from this rapidly changing ocean. Profiles of dissolved Fe from recent Japanese field efforts in the Western Canada Basin (2008, 2010) indicate the broad Chukchi Shelf as a source of Fe to the halocline of the Western Canada Basin. Here we present dissolved and particulate data for crustal (Al, Mn, Fe) and non-crustal elements (Co, Cu, Zn) from the productive Chukchi Sea to characterize the sedimentary input of these metals to shelf waters contributing to the halocline layer of the Canada Basin. Water column profiles were collected in late summer 2013 onboard the R/V Mirai at 10 stations from the Bering Strait to the slope, and at a time-series (10 days) station located over the outer shelf. A narrow and variable (5-10 m) benthic boundary layer was sampled at the time-series station with highly elevated dissolved and suspended particulate metal concentrations. High metal concentrations were also observed in the subsurface at a station over Barrow Canyon where mixing is enhanced. Reactivity of suspended particulate metals was determined by the leachable vs. refractory fractions. Metal concentrations were determined by ICP-MS. Trace metal transport from the shelf to the interior will be discussed in context with shelf mechanisms contributing to this export, and to expected future changes in the Arctic Ocean.

  20. Igneous-sedimentary petroleum systems; Sistemas petroliferos igneo-sedimentares

    Energy Technology Data Exchange (ETDEWEB)

    Eiras, Jaime Fernandes [Para Univ., Belem, PA (Brazil)]. E-mail: eiras@ufpa.br; Wanderley Filho, Joaquim Ribeiro [PETROBRAS S.A., Manaus, AM (Brazil). Unidade de Negocios-BSOL]. E-mail: jwand@petrobras.com.br

    2003-07-01

    Igneous-sedimentary petroleum systems are mixed systems in which one or more essential elements or processes are related to magmatic events. Many examples worldwide are presented to show the importance of igneous rocks in the exploratory activities, as well as in the petroleum occurrence. Volcanic ash layers are of great importance in stratigraphic correlation and elucidation of structures, particularly when they occur in thick nonfossiliferous strata. They are also good indicators of turbidite deposition where turbidity currents are related to earthquakes generated by magmatic events. Unconventional reservoirs can be created by volcanic eruptions or intrusions, crystallization, reworking, and fracturing. Unaltered igneous rocks can seal vertically and laterally conventional reservoirs due to its excellent cap capacity. Abnormal thermal effect of igneous rocks can compensate the lack of overburden in shallow basins. Structural or combined traps can be formed due to intrusions, such as folded, faulted, and unconformity traps. Porosity can be either primary or secondary, or both. Primary porosity mainly consists of cavities produced by gas volatilization during eruption and cooling. Secondary porosity refers to those pores that result from hydrothermal alteration, recrystallization, and dissolution by groundwater, and tectonic stress. It includes intercrystalline pores formed by crystallization of various secondary minerals, dissolution pores, and tectonic fractures. New technologies of petroleum development and production are encouraging to search for oil and gas within igneous rocks, and new discoveries are expected. (author)

  1. Sedimentary uranium deposits in France and French Union

    International Nuclear Information System (INIS)

    The author gives the actual state of our knowledge on uranium deposits found in recent years. Till now in precambrian formations only one important deposit has been found, at Mounana (Gabon) in a series of conglomeratic sandstones belonging to the 'Francevillien'. The observed mineralization is of the uranium-vanadium type. To the carboniferous formations corresponds in France a series of deposits, among which the most important ones are located at Saint-Hippolyte. Uranium as carburans, organic-bound complexes, is contained in lacustrine schists of Westphalian or lower Stephanian formations. A number of occurrences are also known in permo-triassic formations, particularly in the Vanoise Alps, in the Maritime Alps and in the Herault, where important occurrences have recently been found not far from Lodeve. The cretaceous and tertiary systems contain uranium deposits in phosphate rocks (Morocco, Senegal, Togo, Middle-Congo). Two sedimentary oligocene deposits are known in France. Lastly, the Vinaninkarena deposit in Madagascar, known for a long time, is the only important one reported in the quaternary series. (author)

  2. Antarctic Cenozoic climate history from sedimentary records: ANDRILL and beyond.

    Science.gov (United States)

    McKay, R M; Barrett, P J; Levy, R S; Naish, T R; Golledge, N R; Pyne, A

    2016-01-28

    Mounting evidence from models and geological data implies that the Antarctic Ice Sheet may behave in an unstable manner and retreat rapidly in response to a warming climate, which is a key factor motivating efforts to improve estimates of Antarctic ice volume contributions to future sea-level rise. Here, we review Antarctic cooling history since peak temperatures of the Middle Eocene Climatic Optimum (approx. 50 Ma) to provide a framework for future initiatives to recover sediment cores from subglacial lakes and sedimentary basins in Antarctica's continental interior. While the existing inventory of cores has yielded important insights into the biotic and climatic evolution of Antarctica, strata have numerous and often lengthy time breaks, providing a framework of 'snapshots' through time. Further cores, and more work on existing cores, are needed to reconcile Antarctic records with the more continuous 'far-field' records documenting the evolution of global ice volume and deep-sea temperature. To achieve this, we argue for an integrated portfolio of drilling and coring missions that encompasses existing methodologies using ship- and sea-ice-/ice-shelf-based drilling platforms as well as recently developed seafloor-based drilling and subglacial access systems. We conclude by reviewing key technological issues that will need to be overcome. PMID:26667911

  3. Late Cenozoic sedimentary and tectonic history of south Buton, Indonesia

    Science.gov (United States)

    Fortuin, A. R.; De Smet, M. E. M.; Hadiwasastra, S.; Van Marle, L. J.; Troelstra, S. R.; Tjokrosapoetro, S.

    A description and interpretation are given of the Upper Cenozoic sedimentary record of south Buton. Various sections and outcrops were studied and sampled for their microfossil content, to provide age and paleobathymetrical data. Together with information from the literature, these data from the base for a geohistory analysis to evaluate the vertical motions. Deposition started some 11 Ma ago, after the main deformation of the island, which was related to the collision of a microplate carrying Buton, with the southeast arm of Sulawesi. Coarse and fine terrigenous debris accumulated in a rapidly subsiding foreland basin; subsidence may have exceeded 100 cm/ka. When the rate of subsidence decreased a late Miocene-early Pliocene period of quiet pelagic sedimentation followed. From the late Pliocene onwards (around 3.5 Ma BP) an overall uplift took place, with rates between 30-120 cm/ka. This drastic change is explained by the collision of Buton with a submerged microcontinent that presently forms the Tukang Besi platform, situated southeast of Buton, which interaction resulted in wrench type tectonics and a clockwise rotation of over 60° for south Buton.

  4. Sedimentary environment analysis of Yaojia formation--the ore-hosting stratum of Qianjiadian uranium deposit

    International Nuclear Information System (INIS)

    Qianjiadian uranium deposit is the first uranium deposit discovered in Songliao basin. In this paper, the sedimentary environment of Yaojia formation, the ore-hosting stratum of Qianjiadian uranium deposit and its relationship with uranium mineralization are studied from several aspects such as lithological combination, sedimentary structures, logging curves, thickness ratio of sandstone layer to mudstone layer, sedimentary petrology and petrological geochemistry. The sedimentary features are characterized by the average value 5.0 between thickness ratio of sandstone layer to mudstone layer of Yaojia formation, and typical tabular cross bedding and trough cross bedding. The lithology of Yaojia formation is mostly composed of intermediate to fine-grained sandstone and mudstone with less conglomerate, and the debris grains have moderate sorting and roundness. These indicate that the source area is far, and that the sediments underwent long-distance transportation before deposition. The large scale and stable extension sand body of the Yaojia formation demonstrated the sedimentary features ora large sedimentary basins. Therefore, the sedimentary environment of Yaojia formation in the study area should be far-sourced sandy braided stream in the united great Songliao basin. The uranium mineralization of Qianjiadian deposit is mainly controlled by the sand bodies of channel-bar and point-bar subfacies, and the scale of the mineralization is closely related to that of the sand bodies. (authors)

  5. Emanation-Sedimentary Metallogenic Series and Models of the Proterozoic Rift in the Kangdian Axis

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The Kangdian axis basement can be divided into two tectonic layers. The lower tectonic layer is the crystalline basement which is made up of the Archaean Dibadu Formation and early Proterozoic Dahongshan Group. The former is a kata-metamorphic basic volcano-sedimentary formation of the old geosyncline (old continental nucleus), and the latter is a medium-grade metamorphosed alkali-rich basic volcanic (emanation)-sedimentary formation of the Yuanjiang-Dahongshan marginal rift. They are in disconformable contact. The upper tectonic layer is the folded basement, and made up of the middle-late Proterozoic Kunyang Group. It is the result of Dongchuan-Yuanjiang intercontinental rifting with discordant contract with the underlying and overlying strata. Along with the evolution of Proterozoic from early to late, four types of emanation-sedimentary deposits in the Kangdian axis rift were formed in turn: ① emanation-sedimentary iron-copper-gold deposits related to basic volcanic rocks in the Yuanmou-Dahongshan marginal rift; ② emanation-sedimentary iron-copper deposits related to intermediate-basic volcanic rocks in the early stage of the Dongnchuan-Yuanjiang intercontinental rift; ③ emanation-sedimentary copper deposits related to sedimentary rocks in the middle stage; ④ copper deposits related to the late tectonic reworking. From early to late Proterozoic, with the evolution of the Kangdian axis rift and lowering volcanic basicity, the ore-forming elements also evolved from Fe, Cu and (Au) through Cu and Fe to Cu.

  6. Lithofacies-paleo-geography and uranium sedimentary facies in Hailar basin

    International Nuclear Information System (INIS)

    Cretaceous-Tertiary sedimentary paleo-structure and lithofacies-paleo-geography in Hailar Basin are described. Taking Chenqi coal field as an example, the sedimentary facies pattern of coal-bearing series characterized by alternating sedimentation of fluviatile and lacustrine-swampy facies is reconstructed. It is pointed out that this sedimentary facies not only controls the sedimentation and distribution of syngenetic uranium mineralization, but also is a favourable place that converges uranium-bearing solution and reduces and precipitates uranium for the second time in epigenetic mineralization

  7. Sedimentary textures formed by aqueous processes, Erebus crater, Meridiani Planum, Mars

    Science.gov (United States)

    Grotzinger, J.; Bell, J., III; Herkenhoff, K.; Johnson, J.; Knoll, A.; McCartney, E.; McLennan, S.; Metz, J.; Moore, J.; Squyres, S.; Sullivan, R.; Ahronson, O.; Arvidson, R.; Joliff, B.; Golombek, M.; Lewis, K.; Parker, T.; Soderblom, J.

    2006-12-01

    New observations at Erebus crater (Olympia outcrop) by the Mars Exploration Rover Opportunity between sols 671 and 735 (a sol is a martian day) indicate that a diverse suite of primary and penecontemporaneous sedimentary structures is preserved in sulfate-rich bedrock. Centimeter-scale trough (festoon) cross-lamination is abundant, and is better expressed and thicker than previously described examples. Postdepositional shrinkage cracks in the same outcrop are interpreted to have formed in response to desiccation. Considered collectively, this suite of sedimentary structures provides strong support for the involvement of liquid water during accumulation of sedimentary rocks at Meridiani Planum.

  8. Pollutant lead deposition in the Gulf of Lions over the last century reconstructed from sedimentary records

    International Nuclear Information System (INIS)

    Six sedimentary cores from the Gulf of Lions continental margin collected in the framework of the IVth MTP-MATER project were investigated for stable lead isotopes and 210Pb aspects in order to determine the relevance of marine sediments as liable atmospheric fallout recorders. The mean sedimentary pollutant lead inventory is 110 ± 7 μg/cm2 (102-121, n=6), in good agreement with atmospheric fallout over the last century established from salt marshes sediments study in Camargue. All sedimentary pollutant lead accumulations put back in time evidence maximum values in the mid 70s, in good agreement with anthropogenic emissions. (author)

  9. Scientific investigation in deep boreholes at the Meuse/Haute Marne underground research laboratory, northeastern France

    International Nuclear Information System (INIS)

    From 1994 to 1996, the preliminary investigation carried out by Andra, identified a sector favourable for hosting a laboratory in argillaceous Callovo-Oxfordian formation which has a thickness of 130 m and lies more than 400 m below ground level. In November 1999 Andra began building an Underground Research Laboratory (URL) with a 3D seismic survey over 4 km2. From 2000 to 2004, large programs of boreholes were carried out on site and on the sector in order to define the characteristics of formations, to improve the regional geological and hydrogeological knowledge and to provide an accurate definition of structural features in Callovo-Oxfordian argillites and Dogger limestones. These drilling programs have provided a fine characterization of the argillites on the laboratory area and a good correlation of geological properties at a sector scale. (author)

  10. Parameters controlling fracturing distribution: example of an Upper Jurassic marly-calcareous formation (eastern Paris Basin)

    International Nuclear Information System (INIS)

    Study of fractures along a 490-m vertical section of marl/limestone alternations in the Upper Jurassic (Meuse/Haute-Marne underground research laboratory-eastern Paris Basin) reveals their organization and the different states of palaeo-stress. Type and extension of tectonic structures seem to be controlled principally by lithology and secondary by depth. Also, it appears deviations of Alpine palaeo-stresses between Kimmeridgian and Oxfordian formations. These deviations are related to the presence of marl/limestone contacts. The vertical evolution of current horizontal maximum stress shows a similar behaviour, with deviations at the walls of Callovo-Oxfordian argilites. These results allow us to point out and to discuss the impact of lithology, rheology and depth on fracturing occurrence and distribution. Furthermore, this study suggests the role of Callovo-Oxfordian as a barrier for fracture development between the limestones of Dogger and Oxfordian formations. (authors)

  11. Regional heat flow patterns in the Western Canadian Sedimentary Basin

    Science.gov (United States)

    Majorowicz, J. A.; Jessop, A. M.

    1981-04-01

    The regional geothermal pattern of the Western Canadian Sedimentary Basin has been studied using available temperature data from wells. Average heat conductivity for various geological formations has been estimated on the basis of net rock studies by Canadian Stratigraphie Services. These data and observations of temperature made in "shut-in holes" in some of the oil pools have been used in heat flow estimations by the Bullard method. The geothermal gradient and heat flow within the basin are exceptionally high in comparison with the other world wide Precambrian platform areas. Especially high geothermal gradient areas are found in the northwestern part of the Prairies Basin in Alberta and British Columbia and most of southeastern and southwestern Saskatchewan. Areas of low gradient are found mainly in the Disturbed Belt of the Foothills, southern and southeastern Alberta, and the Peace River area in British Columbia. Neither the analysis of regional heat conductivity distribution nor the heat generation distribution of the basement rock of the Prairies Basin evaluated on the basis of U, Th and K data after Burwash (1979), explain the observed heat flow patterns of the Prairies Basin. Comparison of heat flow patterns with some of the hydrogeological phenomena suggests the significant influence of fluid flow in the basin formations on geothermal features. Low geothermal gradient areas coincide with water recharge areas and high hydraulic head distribution regions. The phenomenon of upward water movement in the deep strata and downward flow through much of the Cenozoic and Mesozoic strata seems to control the regional heat flow distribution in the basin. The analyses of coal metamorphism in the upper and middle Mesozoic formations of the Foothills Belt and in the central Prairies Basin suggest that the pre-Laramide paleogeothermal heat flow distribution was different from the present one. It is very probable that the Foothills Belt area was characterized by a higher

  12. Rapid imbibition of water in fractures within unsaturated sedimentary rock

    Science.gov (United States)

    Cheng, C.-L.; Perfect, E.; Donnelly, B.; Bilheux, H. Z.; Tremsin, A. S.; McKay, L. D.; DiStefano, V. H.; Cai, J. C.; Santodonato, L. J.

    2015-03-01

    The spontaneous imbibition of water and other liquids into gas-filled fractures in variably-saturated porous media is important in a variety of engineering and geological contexts. However, surprisingly few studies have investigated this phenomenon. We present a theoretical framework for predicting the 1-dimensional movement of water into air-filled fractures within a porous medium based on early-time capillary dynamics and spreading over the rough surfaces of fracture faces. The theory permits estimation of sorptivity values for the matrix and fracture zone, as well as a dispersion parameter which quantifies the extent of spreading of the wetting front. Quantitative data on spontaneous imbibition of water in unsaturated Berea sandstone cores were acquired to evaluate the proposed model. The cores with different permeability classes ranging from 50 to 500 mD and were fractured using the Brazilian method. Spontaneous imbibition in the fractured cores was measured by dynamic neutron radiography at the Neutron Imaging Prototype Facility (beam line CG-1D, HFIR), Oak Ridge National Laboratory. Water uptake into both the matrix and the fracture zone exhibited square-root-of-time behavior. The matrix sorptivities ranged from 2.9 to 4.6 mm s-0.5, and increased linearly as the permeability class increased. The sorptivities of the fracture zones ranged from 17.9 to 27.1 mm s-0.5, and increased linearly with increasing fracture aperture width. The dispersion coefficients ranged from 23.7 to 66.7 mm2 s-1 and increased linearly with increasing fracture aperture width and damage zone width. Both theory and observations indicate that fractures can significantly increase spontaneous imbibition in unsaturated sedimentary rock by capillary action and surface spreading on rough fracture faces. Fractures also increase the dispersion of the wetting front. Further research is needed to investigate this phenomenon in other natural and engineered porous media.

  13. High-resolution sedimentary records of heavy metals in Guangzhou section of the Pearl River, South China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The sedimentary feature and variation of heavy metals in ca. 100 years, especially in the last three decades, in the riverbed of Guangzhou section of the Pearl River were revealed by the sedimentary heavy metal fluxes and total organic carbon (TOC) in a 210Pb-dated sedimentary core. It is suggested that the historical changes of heavy metal contamination can be recorded by pollutant sedimentary fluxes rather than by their concentrations. The heavy metal contamination in the river section was divided into 6 sedimentary historical stages of 3 groups, which correspond to the economic development and regional urbanization process.

  14. Postglacial sedimentary infill of the Bricial peatland (Cantabrian Mountains, Spain)

    Science.gov (United States)

    Correia, Antonio; Ruiz-Fernández, Jesús; Oliva, Marc; Fernández, Antonio; García-Hernández, Cristina; Gallinar, David

    2016-04-01

    Bricial is a peatland located in a glaciokarst depression of the Western Massif of the Picos de Europa (NW Spain). The depression is 425 m long and 245 m wide, and it is surrounded by moraines built during the stage of glacial expansion after the maximum advance within the Last Glaciation. In contrast to what happens in other karstic depressions existing in this massif (e.g. Comeya), the thickness and sedimentary infill of this depression is still unknown. With the purpose of better knowing the depression's structure, two electrical resistivity tomographies (ERT)s with different lengths across the Bricial depression were conducted along perpendicular directions; the shortest ERT was done in a NNE-SSW direction with an electrode spacing of 2 m and a total length of 78 m; the longest ERT was done in a WNW-ESE direction with a 5 m electrode spacing and a total length of 195 m. Both ERTs used 40 electrodes in a Wenner configuration. The two ERTs were done in such way that they intersected near an 8 m deep borehole drilled in the area in 2006. A two-dimensional electrical inversion software was used for inverting the apparent electrical resistivity data obtained during the field work into two-dimensional models of electrical resistivity of the ground. The models are a representation of the distribution of the electrical resistivity of the ground to depths of about 14 m along the shortest ERT and 35 m along the longest. In both geoelectrical models the electrical structure is approximately horizontal at the surface (i.e., between 3 to 5 m depth) and is more complex as depth increases. Low resistivity values prevail in most part of the profiles, which is consistent with the sedimentary sequence collected in the area. The 8 m long sedimentary sequence collected from Bricial consists of homogeneous organic-rich sediments. The base of the sequence was dated at 11,150 ± 900 cal yr BP. Taking into account the sedimentation rates and the data inferred from the electrical

  15. Elemental Geochemistry of Sedimentary Rocks at Yellowknife Bay, Gale Crater, Mars

    Science.gov (United States)

    McLennan, S. M.; Anderson, R. B.; Bell, J. F.; Bridges, J. C.; Calef, F.; Campbell, J. L.; Clark, B. C.; Clegg, S.; Conrad, P.; Cousin, A.; Des Marais, D. J.; Dromart, G.; Dyar, M. D.; Edgar, L. A.; Ehlmann, B. L.; Fabre, C.; Forni, O.; Gasnault, O.; Gellert, R.; Gordon, S.; Grant, J. A.; Grotzinger, J. P.; Gupta, S.; Herkenhoff, K. E.; Hurowitz, J. A.; King, P. L.; Le Mouélic, S.; Leshin, L. A.; Léveillé, R.; Lewis, K. W.; Mangold, N.; Maurice, S.; Ming, D. W.; Morris, R. V.; Nachon, M.; Newsom, H. E.; Ollila, A. M.; Perrett, G. M.; Rice, M. S.; Schmidt, M. E.; Schwenzer, S. P.; Stack, K.; Stolper, E. M.; Sumner, D. Y.; Treiman, A. H.; VanBommel, S.; Vaniman, D. T.; Vasavada, A.; Wiens, R. C.; Yingst, R. A.; Kemppinen, Osku; Bridges, Nathan; Johnson, Jeffrey R.; Minitti, Michelle; Cremers, David; Farmer, Jack; Godber, Austin; Wadhwa, Meenakshi; Wellington, Danika; McEwan, Ian; Newman, Claire; Richardson, Mark; Charpentier, Antoine; Peret, Laurent; Blank, Jennifer; Weigle, Gerald; Li, Shuai; Milliken, Ralph; Robertson, Kevin; Sun, Vivian; Baker, Michael; Edwards, Christopher; Farley, Kenneth; Griffes, Jennifer; Miller, Hayden; Newcombe, Megan; Pilorget, Cedric; Siebach, Kirsten; Brunet, Claude; Hipkin, Victoria; Marchand, Geneviève; Sánchez, Pablo Sobrón; Favot, Laurent; Cody, George; Steele, Andrew; Flückiger, Lorenzo; Lees, David; Nefian, Ara; Martin, Mildred; Gailhanou, Marc; Westall, Frances; Israël, Guy; Agard, Christophe; Baroukh, Julien; Donny, Christophe; Gaboriaud, Alain; Guillemot, Philippe; Lafaille, Vivian; Lorigny, Eric; Paillet, Alexis; Pérez, René; Saccoccio, Muriel; Yana, Charles; Armiens-Aparicio, Carlos; Rodríguez, Javier Caride; Blázquez, Isaías Carrasco; Gómez, Felipe Gómez; Gómez-Elvira, Javier; Hettrich, Sebastian; Malvitte, Alain Lepinette; Jiménez, Mercedes Marín; Martínez-Frías, Jesús; Martín-Soler, Javier; Martín-Torres, F. Javier; Jurado, Antonio Molina; Mora-Sotomayor, Luis; Caro, Guillermo Muñoz; López, Sara Navarro; Peinado-González, Verónica; Pla-García, Jorge; Manfredi, José Antonio Rodriguez; Romeral-Planelló, Julio José; Fuentes, Sara Alejandra Sans; Martinez, Eduardo Sebastian; Redondo, Josefina Torres; Urqui-O'Callaghan, Roser; Mier, María-Paz Zorzano; Chipera, Steve; Lacour, Jean-Luc; Mauchien, Patrick; Sirven, Jean-Baptiste; Manning, Heidi; Fairén, Alberto; Hayes, Alexander; Joseph, Jonathan; Squyres, Steven; Sullivan, Robert; Thomas, Peter; Dupont, Audrey; Lundberg, Angela; Melikechi, Noureddine; Mezzacappa, Alissa; DeMarines, Julia; Grinspoon, David; Reitz, Günther; Prats, Benito; Atlaskin, Evgeny; Genzer, Maria; Harri, Ari-Matti; Haukka, Harri; Kahanpää, Henrik; Kauhanen, Janne; Kemppinen, Osku; Paton, Mark; Polkko, Jouni; Schmidt, Walter; Siili, Tero; Wray, James; Wilhelm, Mary Beth; Poitrasson, Franck; Patel, Kiran; Gorevan, Stephen; Indyk, Stephen; Paulsen, Gale; Bish, David; Schieber, Juergen; Gondet, Brigitte; Langevin, Yves; Geffroy, Claude; Baratoux, David; Berger, Gilles; Cros, Alain; d'Uston, Claude; Lasue, Jérémie; Lee, Qiu-Mei; Meslin, Pierre-Yves; Pallier, Etienne; Parot, Yann; Pinet, Patrick; Schröder, Susanne; Toplis, Mike; Lewin, Éric; Brunner, Will; Heydari, Ezat; Achilles, Cherie; Oehler, Dorothy; Sutter, Brad; Cabane, Michel; Coscia, David; Israël, Guy; Szopa, Cyril; Robert, François; Sautter, Violaine; Buch, Arnaud; Stalport, Fabien; Coll, Patrice; François, Pascaline; Raulin, François; Teinturier, Samuel; Cameron, James; DeLapp, Dorothea; Dingler, Robert; Jackson, Ryan Steele; Johnstone, Stephen; Lanza, Nina; Little, Cynthia; Nelson, Tony; Williams, Richard B.; Jones, Andrea; Kirkland, Laurel; Baker, Burt; Cantor, Bruce; Caplinger, Michael; Davis, Scott; Duston, Brian; Edgett, Kenneth; Fay, Donald; Hardgrove, Craig; Harker, David; Herrera, Paul; Jensen, Elsa; Kennedy, Megan R.; Krezoski, Gillian; Krysak, Daniel; Lipkaman, Leslie; Malin, Michael; McCartney, Elaina; McNair, Sean; Nixon, Brian; Posiolova, Liliya; Ravine, Michael; Salamon, Andrew; Saper, Lee; Stoiber, Kevin; Supulver, Kimberley; Van Beek, Jason; Van Beek, Tessa; Zimdar, Robert; French, Katherine Louise; Iagnemma, Karl; Miller, Kristen; Summons, Roger; Goesmann, Fred; Goetz, Walter; Hviid, Stubbe; Johnson, Micah; Lefavor, Matthew; Lyness, Eric; Breves, Elly; Fassett, Caleb; Blake, David F.; Bristow, Thomas; Edwards, Laurence; Haberle, Robert; Hoehler, Tori; Hollingsworth, Jeff; Kahre, Melinda; Keely, Leslie; McKay, Christopher; Wilhelm, Mary Beth; Bleacher, Lora; Brinckerhoff, William; Choi, David; Dworkin, Jason P.; Eigenbrode, Jennifer; Floyd, Melissa; Freissinet, Caroline; Garvin, James; Glavin, Daniel; Harpold, Daniel; Jones, Andrea; Mahaffy, Paul; Martin, David K.; McAdam, Amy; Pavlov, Alexander; Raaen, Eric; Smith, Michael D.; Stern, Jennifer; Tan, Florence; Trainer, Melissa; Meyer, Michael; Posner, Arik; Voytek, Mary; Anderson, Robert C.; Aubrey, Andrew; Beegle, Luther W.; Behar, Alberto; Blaney, Diana; Brinza, David; Christensen, Lance; Crisp, Joy A.; DeFlores, Lauren; Ehlmann, Bethany; Feldman, Jason; Feldman, Sabrina; Flesch, Gregory; Jun, Insoo; Keymeulen, Didier; Maki, Justin; Mischna, Michael; Morookian, John Michael; Parker, Timothy; Pavri, Betina; Schoppers, Marcel; Sengstacken, Aaron; Simmonds, John J.; Spanovich, Nicole; Juarez, Manuel de la Torre; Webster, Christopher R.; Yen, Albert; Archer, Paul Douglas; Cucinotta, Francis; Jones, John H.; Niles, Paul; Rampe, Elizabeth; Nolan, Thomas; Fisk, Martin; Radziemski, Leon; Barraclough, Bruce; Bender, Steve; Berman, Daniel; Dobrea, Eldar Noe; Tokar, Robert; Williams, Rebecca M. E.; Cleghorn, Timothy; Huntress, Wesley; Manhès, Gérard; Hudgins, Judy; Olson, Timothy; Stewart, Noel; Sarrazin, Philippe; Vicenzi, Edward; Wilson, Sharon A.; Bullock, Mark; Ehresmann, Bent; Hamilton, Victoria; Hassler, Donald; Peterson, Joseph; Rafkin, Scot; Zeitlin, Cary; Fedosov, Fedor; Golovin, Dmitry; Karpushkina, Natalya; Kozyrev, Alexander; Litvak, Maxim; Malakhov, Alexey; Mitrofanov, Igor; Mokrousov, Maxim; Nikiforov, Sergey; Prokhorov, Vasily; Sanin, Anton; Tretyakov, Vladislav; Varenikov, Alexey; Vostrukhin, Andrey; Kuzmin, Ruslan; Wolff, Michael; Botta, Oliver; Drake, Darrell; Bean, Keri; Lemmon, Mark; Lee, Ella Mae; Sucharski, Robert; Hernández, Miguel Ángel de Pablo; Ávalos, Juan José Blanco; Ramos, Miguel; Kim, Myung-Hee; Malespin, Charles; Plante, Ianik; Muller, Jan-Peter; Navarro-González, Rafael; Ewing, Ryan; Boynton, William; Downs, Robert; Fitzgibbon, Mike; Harshman, Karl; Morrison, Shaunna; Dietrich, William; Kortmann, Onno; Palucis, Marisa; Williams, Amy; Lugmair, Günter; Wilson, Michael A.; Rubin, David; Jakosky, Bruce; Balic-Zunic, Tonci; Frydenvang, Jens; Jensen, Jaqueline Kløvgaard; Kinch, Kjartan; Koefoed, Asmus; Madsen, Morten Bo; Stipp, Susan Louise Svane; Boyd, Nick; Pradler, Irina; Jacob, Samantha; Owen, Tobias; Rowland, Scott; Atlaskin, Evgeny; Savijärvi, Hannu; Boehm, Eckart; Böttcher, Stephan; Burmeister, Sönke; Guo, Jingnan; Köhler, Jan; García, César Martín; Mueller-Mellin, Reinhold; Wimmer-Schweingruber, Robert; McConnochie, Timothy; Benna, Mehdi; Franz, Heather; Bower, Hannah; Brunner, Anna; Blau, Hannah; Boucher, Thomas; Carmosino, Marco; Atreya, Sushil; Elliott, Harvey; Halleaux, Douglas; Rennó, Nilton; Wong, Michael; Pepin, Robert; Elliott, Beverley; Spray, John; Thompson, Lucy; Williams, Joshua; Vasconcelos, Paulo; Bentz, Jennifer; Nealson, Kenneth; Popa, Radu; Kah, Linda C.; Moersch, Jeffrey; Tate, Christopher; Day, Mackenzie; Kocurek, Gary; Hallet, Bernard; Sletten, Ronald; Francis, Raymond; McCullough, Emily; Cloutis, Ed; ten Kate, Inge Loes; Kuzmin, Ruslan; Arvidson, Raymond; Fraeman, Abigail; Scholes, Daniel; Slavney, Susan; Stein, Thomas; Ward, Jennifer; Berger, Jeffrey; Moores, John E.

    2014-01-01

    Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved, indicating arid, possibly cold, paleoclimates and rapid erosion and deposition. The absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low-temperature, circumneutral pH, rock-dominated aqueous conditions. Analyses of diagenetic features (including concretions, raised ridges, and fractures) at high spatial resolution indicate that they are composed of iron- and halogen-rich components, magnesium-iron-chlorine-rich components, and hydrated calcium sulfates, respectively. Composition of a cross-cutting dike-like feature is consistent with sedimentary intrusion. The geochemistry of these sedimentary rocks provides further evidence for diverse depositional and diagenetic sedimentary environments during the early history of Mars.

  16. DETERMINATION OF TECTONIC EVOLUTION OF A SEDIMENTARY BASIN FROM SANDSTONE COMPONENTS

    Institute of Scientific and Technical Information of China (English)

    Lei SHAO; Chuanlian LIU; Karl STATTEGGER

    2001-01-01

    Terrigenous sedimentary rocks are the dominant rock types in continental sedimentary basin, the components of these rocks are mainly controlled by source rocks. Through systematically analyzing the components of terrigenous sedimentary rocks, the tectonic evolution of a sedimentary basin can be reconstructed. The Turpan Basin was examined using sandstone petrological and geochemical methods.The consistency of the petrographical and geochemical results shows that the tectonic evolution of the basin can be subdivided into four stages: the first stage covers the Permian; the second stage the Triassic;the third stage from the Lower Jurassic to Upper Jurassic and the fourth stage from the Cretaceous to Tertiary. The components of sandstones among these stages are different, which reflect the influence of tectonics movements on the evolution of the basin and surrounding areas.

  17. A baseline study of trace metals in a coral reef sedimentary environment, Lakshadweep Archipelago

    Digital Repository Service at National Institute of Oceanography (India)

    Gopinath, A.; Nair, S.M.; Kumar, N.C.; Jayalakshmi, K.V.; Pamalal, D.

    Surficial and core samples collected from the sedimentary microenvironments of Lakshadweep Archipelago were analysed for their trace metal contents. The synoptical relations in spatial distributions with respect to environmental conditions such as p...

  18. Granulometric analyses of pelites using a sedigraph: Examples from a Volcano-sedimentary environment

    Digital Repository Service at National Institute of Oceanography (India)

    Mascarenhas, A

    This article presents granulometric data of pelites (less than 40 microns) of mixed composition from a volcano-sedimentary environment. The sedigraph serves as an useful tool in the analyses of silt-clay fraction of marine sediments. A cumulative...

  19. Evidence from carbon isotope measurements for diverse origins of sedimentary hydrocarbons

    Science.gov (United States)

    Freeman, K. H.; Hayes, J. M.; Trendel, J. M.; Albrecht, P.

    1990-01-01

    The organic matter found in sedimentary rocks must derive from many sources; not only from ancient primary producers but also from consumers and secondary producers. In all of these organisms, isotope effects can affect the abundance and distribution of 13C in metabolites. Here, by using an improved form of a previously described technique in which the effluent of a gas chromatograph is continuously analysed isotopically, we report evidence of the diverse origins of sedimentary organic matter. The record of 13C abundances in sedimentary carbonate and total organic carbon can be interpreted in terms of variations in the global carbon cycle. Our results demonstrate, however, that isotope variations within sedimentary organic mixtures substantially exceed those observed between samples of total organic carbon. Resolution of isotope variations at the molecular level offers a new and convenient means of refining views both of localized palaeoenvironments and of control mechanisms within the global carbon cycle.

  20. Basin Fluid Mineralization during Multistage Evolution of the Lanping Sedimentary Basin, Southwestern China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The Lanping sedimentary basin has experienced a five-stage evolution since the late Paleozoic: ocean-continent transformation (late Paleozoic to early mid-Triassic); intracontinental rift basin (late mid-Triassic to early Jurassic); down-warped basin (middle to late Jurassic); foreland basin (Cretaceous); and strike-slip basin (Cenozoic). Three major genetic types of Ag-Cu polymetailic ore deposits, including the reworked hydrothermal sedimentary, sedimentary-hydrothermally reworked and hydrothermal vein types, are considered to be the products of basin fluid activity at specific sedimentary-tectonic evolutionary stages. Tectonic differences of the different evolutionary stages resulted in considerable discrepancy in the mechanisms of formation-transportation, migration direction and emplacement processes of the basin fluids, thus causing differences in mineralization styles as well as in genetic types of ore deposit.

  1. Elemental geochemistry of sedimentary rocks at Yellowknife Bay, Gale crater, Mars.

    Science.gov (United States)

    McLennan, S M; Anderson, R B; Bell, J F; Bridges, J C; Calef, F; Campbell, J L; Clark, B C; Clegg, S; Conrad, P; Cousin, A; Des Marais, D J; Dromart, G; Dyar, M D; Edgar, L A; Ehlmann, B L; Fabre, C; Forni, O; Gasnault, O; Gellert, R; Gordon, S; Grant, J A; Grotzinger, J P; Gupta, S; Herkenhoff, K E; Hurowitz, J A; King, P L; Le Mouélic, S; Leshin, L A; Léveillé, R; Lewis, K W; Mangold, N; Maurice, S; Ming, D W; Morris, R V; Nachon, M; Newsom, H E; Ollila, A M; Perrett, G M; Rice, M S; Schmidt, M E; Schwenzer, S P; Stack, K; Stolper, E M; Sumner, D Y; Treiman, A H; VanBommel, S; Vaniman, D T; Vasavada, A; Wiens, R C; Yingst, R A

    2014-01-24

    Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved, indicating arid, possibly cold, paleoclimates and rapid erosion and deposition. The absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low-temperature, circumneutral pH, rock-dominated aqueous conditions. Analyses of diagenetic features (including concretions, raised ridges, and fractures) at high spatial resolution indicate that they are composed of iron- and halogen-rich components, magnesium-iron-chlorine-rich components, and hydrated calcium sulfates, respectively. Composition of a cross-cutting dike-like feature is consistent with sedimentary intrusion. The geochemistry of these sedimentary rocks provides further evidence for diverse depositional and diagenetic sedimentary environments during the early history of Mars. PMID:24324274

  2. Astronomical forcing and geochronological application of sedimentary cycles in the Mediterranean Pliocene-Pleistocene

    OpenAIRE

    Hilgen, Frits

    1991-01-01

    A new, astronomically calibrated time scale is presented for the Mediterranean Pliocene based on the correlation of sedimentary cycles to astronomical curves which describe the quasi-periodic variations in the Earth's orbit during the last 5.5 Ma. These sedimentary cycles are found in a continuous deep-sea marl sequence emerged above present sea-level due to tectonic uplift. For this sequence, an integrated high-resolution magnetostratigraphy, (planktonic foraminiferal) biostratigraphy and li...

  3. Provenance of zircon of the lowermost sedimentary cover, Estonia, East-European Craton

    OpenAIRE

    Konsa, M.; Puura, V.

    1999-01-01

    Bulk and accessory mineral composition of fresh and weathered crystalline rocks, and sedimentary deposits overlying the crystalline-sedimentary unconformity have been examined in core samples from 28 drill holes in Estonia. Before the Late Vendian to Early Cambrian regional subsidence and sedimentation, the region represented a flat plateau within the Svecofennian Domain. Palaeo-and Mesoproterozoic crystalline rocks, regardless their different initial mineral composition, subcrop under the Up...

  4. Geophysical Study of the Sedimentary Cover in Darb El-Arbeen, South Western Desert, Egypt

    OpenAIRE

    Zaher, Mohamed Abdel; Sultan, Sultan Awad; El-Said, Alsayed Ahmed; Ehara, Sachio

    2008-01-01

    A Bouguer gravity anomaly map and eight Vertical Electrical Sounding profiles in an area 23o 30’ – 23o 50’ latitude and 30o 00 ’ – 30o 40 ’ E longitude in the southern Western Desert of Egypt were used to determine the thickness of sedimentary cover containing the main water rich sandstone formation. The predominant structures affecting the basement rock and sedimentary cover were also studied. Resistivity surveys are routinely employed in groundwater exploration to locate zone...

  5. The application of high-resolution 3D seismic data to model the distribution of mechanical and hydrogeological properties of a potential host rock for the deep storage of radioactive waste in France

    OpenAIRE

    Mari, Jean-Luc; Yven, Béatrice

    2014-01-01

    In the context of a deep geological repository of high-level radioactive wastes, the French National Radioactive Waste Management Agency (Andra) has conducted an extensive characterization of the Callovo-Oxfordian argillaceous rock and surrounding formations in the Eastern Paris Basin. As part of this project, an accurate 3D seismic derived geological model is needed. The paper shows the procedure used for building the 3D seismic constrained geological model in depth by combining time-to-dept...

  6. Etude expérimentale du comportement thermo-hydro-mécanique de l'argilite du Callovo-Oxfordien

    OpenAIRE

    Mohajerani, Mehrdokht

    2011-01-01

    During the different phases of the exothermic radioactive waste deep disposal (excavation, operation) and after permanent closure, the host rock is submitted to various coupled mechanical, hydraulic and thermal phenomena. Hence, a thorough investigation of the thermo-hydro-mechanical behaviour of the rock is necessary to complete existing data and to better understand and model the short and long term behaviour of the Callovo-Oxfordian (COx) clay formation in Bure (Meuse/Haute-Marne - M/HM), ...

  7. Alteration of nanocrystalline Calcium Silicate Hydrate (C-S-H) at pH 9.2 and room temperature

    OpenAIRE

    Marty, Nicolas C.M.; Grangeon, Sylvain; Warmont, Fabienne; Lerouge, Catherine

    2014-01-01

    In the French design of deep underground radioactive waste disposal, cementitious materials will be used to build access structures, galleries, vaults and waste packages for Intermediate Level Long-lived Waste (ILLW). Part of these cementitious materials will be in physical contact with the Callovo-Oxfordian clay host rock formation (COx). The pH of the COx pore water is around 7 and its composition is very different from the cementitious pore water. Due to this chemical contrast, a chemical ...

  8. Mechanistic study of pyrite reduction by hydrogen in NaCl 0.1 M at 90°C using electrochemical techniques

    OpenAIRE

    Betelu, Stéphanie; Lerouge, Catherine; Berger, Gilles; Giffaut, E.; IGNATIADIS, Ioannis

    2012-01-01

    Nuclear waste repositories are being installed in deep excavated rock formations in some places in Europe to isolate and store radioactive waste. In France, the Callovo-Oxfordian formation (COx) is a potential candidate for a nuclear waste repository. After the closure of the underground nuclear waste repository, aqueous corrosion of the steel canister and, to a lesser extent, radiolysis of water would produce significant amounts of H2. This H2 can interact with materials from the repository ...

  9. H-terminated polycrystalline boron doped diamond electrode for geochemical sensing into underground components of nuclear repositories

    OpenAIRE

    Boussadi, A.; Betelu, Stéphanie; Silva, F.; Ignatiadis, Ioannis

    2012-01-01

    Nuclear waste repositories are being installed in deep excavated rock formations in some places in Europe to isolate and store radioactive waste. In France, Callovo-Oxfordian formation (COx) is potential candidate for nuclear waste repository. It is thus necessary to measure in situ the state of a structure's health during its entire life. The monitoring of the near-field rock and the knowledge of the geochemical transformations can be carried out by a set of sensors for a sustainable managem...

  10. Impact de la fissuration sur les propriétés de rétention d'eau et de transport de gaz des géomatériaux : Application au stockage géologique des déchets radioactifs

    OpenAIRE

    M'Jahad, Sofia

    2012-01-01

    In the context of geological disposal of radioactive waste, this work contributes to the characterization of the effect of diffuse damage on the water retention and gas transfer properties of concrete (CEM I and CEM V) selected by Andra, Callovo-Oxfordian argillite (host rock) and argillite / concrete interfaces. This study provides information on the concrete microstructure from Mercury porosimetry intrusion and water retention curves: each concrete has a distinct microstructure, CEM I concr...

  11. The Punta del Este terrain and its volcano sedimentary cover, metamorphic and sedimentary: geology, geochemistry and geochronology

    International Nuclear Information System (INIS)

    Gariep belt it develops over the West Africa coastal region of Namibia underlying on Namaqua metamorphic complex.It characterized by supra crustal rocks affected for a very low to low metamorphism and in two tecto no-stratigraphic units identified by Base i et al 2005 showing that sediments of Formation Rocha in Uruguay and the Group Oranjemund Gariep in S E Africa have similar ages in the provenance of the zircons, suggesting that they were probably deposited in the same basin. This unit exhibits detrital zircons around 600my, sedimentation and metamorphism and deformación occur in a narrow time interval from 600-610 to 574 m (Granite de Castillo intrusion) .Cam pal et al, 2005 proposed to the Cerros Aguirre Formation similar in a range of age of different events. To the east separated from the Punta del Este Terrane –Pelotas. Aigua .Florianopolis batholith s by the shear zone Alferez Cordillera (Preciozzi et al. 1999, Basei et al. 2000) Another option develops this granitic belt is an integral part of Land Punta del Este Terrane(Preciozzi in this work), being deployed on a thin cratonic granite edge. The climax of the post-brasilian magmatism is 580my, strongly related to trans current movements (eg shear zones Major Gercino-Alferez- Cordillera and Sierra Ballena.In South America an old west domain is formed by the Piedra Alta Terrane which integrate the Río de la Pl ata Craton, a central domain intensely reworked by Neoproterozoic events known so far as Nico Perez . The primary coverage is integrated by two volcano-sedimentary basins (San Carlos Formation and Cerros de Aguirre Formation)In this study are considered the Geology,Geochemistry and Geochronology of the different units of Rocha Formation

  12. Jurassic sedimentary features and tectonic settings of southeastern China

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Two types of the Jurassic basins are distinguished in SE China based on their geodynamic features: the Late Triassic-Early Jurassic post-orogenic basins and the Middle Jurassic intra-continental extensional basins. The Lower Jurassic sequence shows a change from coarseto fine-grained accumulation, suggesting a gradually deepening depositional environment from river to shore-lake and to deep-water lake. In contrast, the Middle Jurassic accumulation was changed from claystone to conglomerate along the coastal provinces in SE China, indicative of an initial crustal uplift. The Wuyi Mountains have been a paleogeograghic separating zone since the Middle Jurassic. The Late Jurassic strata are absent in most areas of SE China. A large-scale bimodal intra-continental rift-type volcanism occurred during the Middle Jurassic along a 40-60 km wide and 200 km long area in western Fujian and southern Jiangxi provinces, which is most likely the strongest volcanism in SE China since the Cambrian. The SHRIMP zircon U-Pb analyses on the rhyolite from the Dongkeng basin in the southern Jiangxi area yield a concord U-Pb age of 160±0.5 Ma, providing an upper age limit for the bimodal volcanic eruption. The analyses of the basin features indicate a change of the depositional environment during the interval from Middle Triassic to Late Triassic from a shallow-sea to an intra-continent in SE China in response to the strong collision between the Yangtze and North China Blocks. Sedimentary structures record a southward direction of Early Jurassic paleo-currents, reflecting that their source areas were to the north side. We propose that the Wuyi region was uplifted as early as Middle Jurassic, followed by a wide E-W-trending extended depression and bimodal volcanism in the western foot of the Wuyi Mountains. Presumably the uplift of the Wuyi domain changed the Middle Jurassic paleo geographic outline and formed the transformational tectonic regime from compression to extension as a tectonic

  13. The Multiple Factors and Multiple Stages Involved in Sedimentary Ore Genesis

    Institute of Scientific and Technical Information of China (English)

    叶连俊; 陈其英

    1990-01-01

    Sedimentary mineral deposits cannot be formed by any kind of simple chemical reactions,but are products of a complex multi-episodic process depending on multiple factors,The whole process is governed by a combination of sedimentary,geochemical,biogeochemical,organic geochemical,paleoclimatical,mechanical agents as well as by the properties of relevant earth crust segment and its structural making up and tectonic mobility A Sedimentary ore deposit is nothing but a special kind of sedimentary facies,characterized by definite sedimentary assemblages,Different genetic types of ore deposit and different ore associations characterize different sedimentary assemblages in different ore-forming belts.Crustal movement,including orogenic,epeirogenic and,oparticularly eustatic events,controls the formation and distribution of all kinds of sedimentary mineral deposits,most of which occur within the transgression front in the lower part of marine transpressive series.Mineral deposits of economic importance cannot be precipitated directly from sea water,but are products of terrestrial imbibition,biological enrichment and pore water concentration instead,Deposits formed above the wave base in the inner continental shelf under strong dynamic condition of sea water are often large and predominantly clastic in texture with commercial grade.Below the wave base in the outer continental shelf environment,where it is more or less dynamically stagnant and oxygen-deficient,the resulted in dustrial ore deposits are mostly of diagenetic or strata-bound type,formed through deep-burying diagenesis.The theory of multi-factor and multi-episodic metallogenesis includes three major aspects:the ore-forming process,the sedimentary environment and the geological background.The study of the forma tion process itself and the sources of ore-forming elements would provide useful clues to further prospectiong Whereas,invstigations of the sedimentary environments should shed light on the spacial

  14. Rivers on Titan - numerical modelling of sedimentary structures

    Science.gov (United States)

    Misiura, Katarzyna; Czechowski, Leszek

    2016-07-01

    flow and of the sedimentation on Titan and on the Earth. Our preliminary results indicate that suspended load is the main way of transport in simulated Titan's conditions. We also indicate that braided rivers appears for larger range of slope on Titan (e.g. S=0.01-0.04) than on Earth (e.g. S=0.004-0.009). Also, for the same type of river, the grain size on Titan is at least 10 times larger than on Earth (1 cm for Titan versus 1 mm for the Earth). It is very interesting that on Titan braided rivers appear even for very little discharge (e.g. Q=30m3/s) and for very large grain size (e.g. 10 cm). In the future we plan the experimental modelling in sediment basin to confirm results from computer modelling. Acknowledgements We are very grateful to Yaoxin Zhang and Yafei Jia from National Center for Computational Hydroscience and Engineering for providing their program - CCHE2D. References [1] Misiura, K., Czechowski, L., 2015. Numerical modelling of sedimentary structures in rivers on Earth and Titan. Geological Quarterly, 59(3): 565-580. [2] Witek, P., Czechowski, L., 2015. Dynamical modeling of river deltas on Titan and Earth. Planet. Space. Sci., 105: 65-79.

  15. Simulations of hydraulic fracturing and leakage in sedimentary basins

    Energy Technology Data Exchange (ETDEWEB)

    Lothe, Ane Elisabeth

    2004-01-01

    Hydraulic fracturing and leakage of water through the caprock is described from sedimentary basin over geological time scale. Abnormal pressure accumulations reduce the effective stresses in the underground and trigger the initiation of hydraulic fractures. The major faults in the basin define these pressure compartments. In this Thesis, basin simulations of hydraulic fracturing and leakage have been carried out. A simulator (Pressim) is used to calculate pressure generation and dissipitation between the compartments. The flux between the compartments and not the flow within the compartments is modelled. The Griffith-Coulomb failure criterion determines initial failure at the top structures of overpressured compartments, whereas the frictional sliding criterion is used for reactivation along the same fractures. The minimum horizontal stress is determined from different formulas, and an empirical one seems to give good results compared to measured pressures and minimum horizontal stresses. Simulations have been carried out on two datasets; one covering the Halten Terrace area and one the Tune Field area in the northern North Sea. The timing of hydraulic fracturing and amount of leakage has been quantified in the studies from the Halten Terrace area. This is mainly controlled by the lateral fluid flow and the permeability of the major faults in the basin. Low fault permeability gives early failure, while high fault permeabilities results in no or late hydraulic fracturing and leakage from overpressured parts of the basin. In addition to varying the transmissibility of all faults in a basin, the transmissibility across individual faults can be varied. Increasing the transmissibility across faults is of major importance in overpressured to intermediately pressured areas. However, to obtain change in the flow, a certain pressure difference has to be the situation between the different compartments. The coefficient of internal friction and the coefficient of frictional

  16. Provenance of zircon of the lowermost sedimentary cover, Estonia, East-European Craton

    Directory of Open Access Journals (Sweden)

    Konsa, M.

    1999-12-01

    Full Text Available Bulk and accessory mineral composition of fresh and weathered crystalline rocks, and sedimentary deposits overlying the crystalline-sedimentary unconformity have been examined in core samples from 28 drill holes in Estonia. Before the Late Vendian to Early Cambrian regional subsidence and sedimentation, the region represented a flat plateau within the Svecofennian Domain. Palaeo-and Mesoproterozoic crystalline rocks, regardless their different initial mineral composition, subcrop under the Upper Vendian/Lower Cambrian sedimentary cover as usually intensely weathered rocks (saprolites composed of residual quartz, altered micas and prevailing clay minerals mainly of the kaolinite group. Thus, the bulk mineral composition of any basement crystalline rocks imparts no specific inherited rock-forming minerals into the covering sedimentary rocks. From the variety of accessory and opaque minerals of crystalline rocks, only zircon populations survived in saprolites. Crystalline rocks of different origin yield different zircons. Relationships between the zircon typology of the basement rocks having specific areas of distribution and the sedimentary rocks immediately overlying those crystalline rocks were the main subject of this study. The result is that siliciclastic sedimentary rocks covering weathered crystalline rocks only in places inherited zircons with typological features characteristic of specific basement areas. In northeastern Estonia, local lenses of the Oru Member (the earliest Upper Vendian sedimentary rocks in Estonia resembling the debris of weathered crystalline rocks yield accessory zircon which in a 1-2 m thick layer above the basement surface is similar to the zircons of the underlying weathering mantle of certain crystalline rocks. In the next unit, the Moldova Member, up to 43 m above the basement surface, a mixture of zircons resembling those of various local basement rocks has been found. Further upwards, in the Vendian and Lower

  17. Sedimentary characteristics of tide-dominated estuary in Donghetang Formation(Upper Devonian), central Tarim Basin

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The Donghetang Formation (Upper Devonian) in central Tarim Basin has been thought an important oil and gas reservoir since the abundant oil and gas resources were found in the wells W16, W20, W34, and other fields. However, the sedimentary environment of the Donghetang Formation has been disputed because it suffered from both tidal and fluvial actions and there were not rich fossils in the sandstone. After the authors analyzed sedimentary features by means of drill cores, well logging data, paleosols, and with SEM obseruations, three kinds of sedimentary environments were distinguished: alluvial fan, tide-dominated estuary, and shelf. Particularly, the sedimentary features of tide-dominated estuary were studied in detail. Besides, the authors discussed sedimentary characteristics of the Donghetang Formation which was divided into two fourth-order sequences and five system tracts. At the same time, according to the forming process of five system tracts, the whole vertical evolution and lateral transition of tide-dominated estuary were illustrated clearly. Finally, the reservoir quality was evaluated based on porosity and permeability.

  18. Research on 3D Distribution of Meandering River Sand Body Using Sedimentary Facies Method and 3D Geological Modeling

    Institute of Scientific and Technical Information of China (English)

    WU Jian; CAO Dai-yong

    2006-01-01

    Sedimentary facies study is an important method in describing the property and distribution of reservoir. 3D geological modeling is a powerful tool in 3D characterization of geological bodies. By combining the sedimentary facies study with 3D geological modeling to generate 3D sedimentary facies model, the 3D geometry and distribution feature of sand bodies can be more accurately characterized, particularly in 3D view. In Liuchu oilfield of Jizhong depression, the Ed2IV formation was recognized as meandering river deposition facies and five sedimentary facies were identified, which include point bar sand, levee, channel margin, abandoned channel and floodplain. All the 24 sand body facies in Ed2IV were mapped and the 3D sedimentary facies model established based on 2D facies maps. The result shows that the 3D sedimentary facies model is well matched for the research result of sedimentary facies. Being an extension of traditional sedimentary study, the 3D sedimentary facies model can be used to describe the 3D geometry and distribution orders of a single sand body more reliably and more accurately.

  19. Sedimentary Mounds on Mars: Tracing Present-day Formation Processes into the Past

    Science.gov (United States)

    Niles, P. B.; Michalski, J.; Edwards, C. S.

    2014-01-01

    High resolution photography and spectroscopy of the martian surface (MOC, HiRISE) from orbit has revolutionized our view of Mars with one and revealed spectacular views of finely layered sedimentary materials throughout the globe [1]. Some of these sedimentary deposits are 'mound' shaped and lie inside of craters (Fig 1). Crater mound deposits are found throughout the equatorial region, as well as ice-rich deposits found in craters in the north and south polar region [2-4]. Despite their wide geographical extent and varying volatile content, the 'mound' deposits have a large number of geomorphic and structural similarities that suggest they formed via equivalent processes. Thus, modern depositional processes of ice and dust can serve as an invaluable analog for interpreting the genesis of ancient sedimentary mound deposits.

  20. Palynostratigraphy of the Erkovtsy field of brown coal (the Zeya-Bureya sedimentary basin)

    Energy Technology Data Exchange (ETDEWEB)

    Kezina, T.V.; Litvinenko, N.D. [Amur State University, Blagoveshchensk (Russian Federation)

    2007-08-15

    The Erkovtsy brown coal field in the northwestern Zeya-Bureya sedimentary basin (129-130{sup o}E, 46-47{sup o}N) is structurally confined to southern flank of the Mesozoic-Cenozoic Belogor'e depression. The verified stratigraphic scheme of the coalfield sedimentary sequence is substantiated by palynological data on core samples from 18 boreholes sampled in the course of detailed prospecting and by paleobotanical analysis of sections in the Yuzhnyi sector of the coalfield (data of 1998 by M.A. Akhmetiev and S.P. Manchester). Sections of the Erkovtsy, Arkhara-Boguchan, and Raichikha brown-coal mines are correlated. Stratigraphic subdivisions distinguished in the studied sedimentary succession are the middle and upper Tsagayan subformations (the latter incorporating the Kivda Beds), Raichikha, Mukhino, Buzuli, and Sazanka formations.

  1. Sedimentary basin analysis using airborne gravity data: a case study from the Bohai Bay Basin, China

    Science.gov (United States)

    Li, Wenyong; Liu, Yanxu; Zhou, Jianxin; Zhou, Xihua; Li, Bing

    2015-12-01

    In this paper, we discuss the application of an airborne gravity survey to sedimentary basin analysis. Using high-precision airborne gravity data constrained by drilling and seismic data from the Bohai Bay Basin in eastern China, we interpreted faults, structural elements, sedimentary thickness, structural styles and local structures (belts) in the central area of the Basin by the wavelet transform method. Subsequently, these data were subtracted from the Bouguer gravity to calculate the residual gravity anomalies. On this basis, the faults were interpreted mainly by linear zones of high gravity gradients and contour distortion, while the sedimentary thicknesses were computed by the Euler deconvolution. The structural styles were identified by the combination of gravity anomalies and the local structures interpreted by the first vertical derivative of the residual gravity. The results showed evidence for seven faults, one sag and ten new local structure belts.

  2. Sedimentary environments of organic matter from Middle Permian source rocks in northern Xinjiang,China

    Institute of Scientific and Technical Information of China (English)

    MIAO Jianyu; KOU Hansheng; ZHOU Lifa; HAN Zhongyuan

    2006-01-01

    A systematic analysis of the inorganic and organic geochemistry of Middle Permian source rocks comprising carbonate rocks and mudstones was carried out, with samples collected from the outcrop and bore of the Junggar, Turpan and Ili basins in northern Xinjiang. This study confirmed that sedimentary parameters for an ancient water body, such as inorganic geochemistry and paleosalinity, have a close relation to the organic matter of source rocks. It is also disclosed that phytane predominance in the source rocks is mainly due to a reducing environment. Biomarkers, such as gammacerane and β-carotene, in the samples reflect a specific salinity in the sedimentary environments. Sedimentary zones with a strong reducing environment are more likely to produce deposits of primary organic matter, which will be buried and preserved contemporarily. Consequently, the source rocks are generally high in organic content and better in organic type than ordinary ones, and vice versa.

  3. Analysis for preliminary evaluation of discrete fracture flow and large-scale permeability in sedimentary rocks

    International Nuclear Information System (INIS)

    Conceptual models for sedimentary rock settings that could be used in future evaluation and suitability studies are being examined through the DOE Repository Technology Program. One area of concern for the hydrologic aspects of these models is discrete fracture flow analysis as related to the estimation of the size of the representative elementary volume, evaluation of the appropriateness of continuum assumptions and estimation of the large-scale permeabilities of sedimentary rocks. A basis for preliminary analysis of flow in fracture systems of the types that might be expected to occur in low permeability sedimentary rocks is presented. The approach used involves numerical modeling of discrete fracture flow for the configuration of a large-scale hydrologic field test directed at estimation of the size of the representative elementary volume and large-scale permeability. Analysis of fracture data on the basis of this configuration is expected to provide a preliminary indication of the scale at which continuum assumptions can be made

  4. Stratigraphy of Upper Cretaceous-Paleogene deposits of northwestern Zeya-Burya sedimentary basin

    Institute of Scientific and Technical Information of China (English)

    T.V. Kezina; N.D. Litvinenko

    2007-01-01

    In the northwestern Zeya-Bureya sedimentary basin, the authors studied coal deposits, including Ivanovsko-Erkovetskyu brown coal square on which is worked off largest Erkovetsky field of brown coal, extending to south flank of the Mesozoic-Cenozoic Belogor'e depression. The verified stratigraphic scheme of the coalfield sedimentary sequence is substantiated by palynological data on core samples from 18 boreholes sampled in the course of detailed prospecting and by paleobotanical analysis of sections in the Yuzhnyi sector of the coalfield. Sections of the Erkovtsy, Arkhara Boguchan, and Raichikha brown-coal mines are correlated. Stratigraphic subdivisions distinguished in the studied sedimentary succession are the middle and upper Tsagayan subformations (the latter incorporating the Kivda Beds), Raichikha and Mukhino formations.

  5. Generation of hydrocarbon gases in modern sedimentary and volcanogenic sedimentary formations of the eastern and southern parts of the Atlantic Ocean

    Energy Technology Data Exchange (ETDEWEB)

    Veber, V.V.; Sazonov, M.L.; Morozova, S.N.; Gershanovich, D.E.; Zarikhin, I.P.; Chernov, V.I.

    1977-01-01

    A study is made of contemporary gas formation based on data on valcano-genic-sedimentary layers of the southern part of the Atlantic and carbon layers of the eastern part of the Atlantic as well as terrigenous residues of the Skoskh Sea. A broad range of deposit facies was established in which there occurs a natural generation of gaseous hydrocarbons (including those heavier than methane). 2 figures, 2 tables.

  6. Displacement propagators of brine flowing within different types of sedimentary rock.

    Science.gov (United States)

    Verganelakis, Dimitris A; Crawshaw, John; Johns, Michael L; Mantle, Michael D; Scheven, Ulrich; Sederman, Andrew J; Gladden, Lynn F

    2005-02-01

    This paper explores the correlation between different microstructural characteristics of porous sedimentary rocks and the flow properties of a Newtonian infiltrating fluid. Preliminary results of displacement propagator measurements of brine solution flowing through two types of sedimentary rock cores are reported. The two types of rocks, Bentheimer and Portland, are characterized by different porosities, pore-size distributions and permeabilities. Propagators have been measured for brine flow rates of 1 and 5 ml/min. Significant differences are seen between the propagators recorded for the two rocks, and these are related to the spatial distribution of porosity within these porous media. PMID:15833644

  7. Estimating tectonic history through basin simulation-enhanced seismic inversion: Geoinformatics for sedimentary basins

    Science.gov (United States)

    Tandon, K.; Tuncay, K.; Hubbard, K.; Comer, J.; Ortoleva, P.

    2004-01-01

    A data assimilation approach is demonstrated whereby seismic inversion is both automated and enhanced using a comprehensive numerical sedimentary basin simulator to study the physics and chemistry of sedimentary basin processes in response to geothermal gradient in much greater detail than previously attempted. The approach not only reduces costs by integrating the basin analysis and seismic inversion activities to understand the sedimentary basin evolution with respect to geodynamic parameters-but the technique also has the potential for serving as a geoinfomatics platform for understanding various physical and chemical processes operating at different scales within a sedimentary basin. Tectonic history has a first-order effect on the physical and chemical processes that govern the evolution of sedimentary basins. We demonstrate how such tectonic parameters may be estimated by minimizing the difference between observed seismic reflection data and synthetic ones constructed from the output of a reaction, transport, mechanical (RTM) basin model. We demonstrate the method by reconstructing the geothermal gradient. As thermal history strongly affects the rate of RTM processes operating in a sedimentary basin, variations in geothermal gradient history alter the present-day fluid pressure, effective stress, porosity, fracture statistics and hydrocarbon distribution. All these properties, in turn, affect the mechanical wave velocity and sediment density profiles for a sedimentary basin. The present-day state of the sedimentary basin is imaged by reflection seismology data to a high degree of resolution, but it does not give any indication of the processes that contributed to the evolution of the basin or causes for heterogeneities within the basin that are being imaged. Using texture and fluid properties predicted by our Basin RTM simulator, we generate synthetic seismograms. Linear correlation using power spectra as an error measure and an efficient quadratic

  8. Typification and regionalization of the Chernobyl exclusion zone sedimentary cover for hydrogeological monitoring

    International Nuclear Information System (INIS)

    Geological findings obtained within the Chernobyl zone territory before and after the accident have been generalized and analyzed. Genetic and stratigrafic division of boreholes and outcrops has permitted identifying typical sedimentary genetic and sedimentary stratigrafic complexes of the cover. Peculiarities of their structure and boundaries of their spreading are determined. It is shown that each of them may be associated with definite regularities of radionuclide migration to the ground water. The latter is necessarily to be taken into account for arrangement of hydrogeological monitoring points and analysis of the monitoring results

  9. In-situ heating test in sedimentary soft rock. Phase 3

    International Nuclear Information System (INIS)

    Various researches have been conducted on high level radioactive waste geological disposal in sedimentary soft rocks. It is noted that the long-term mechanical behaviors of sedimentary soft rocks can be affected by various environmental factors such as temperatures or hydraulic conditions. Therefore, in-situ heating test was conducted in an underground cavern at a depth of 50 m for the purpose of improving thermo-hydro-mechanical coupled analysis code. This report presents the test equipment developed for heating bedrock above 100degC and the test result using this new test equipment. (author)

  10. In-situ heating test in sedimentary soft rock. Phase 2

    International Nuclear Information System (INIS)

    Various researches have been conducted on high level radioactive waste geological disposal in sedimentary soft rocks. It is noted that the long-term mechanical behaviors of sedimentary soft rocks can be affected by various environmental factors such as temperatures or hydraulic conditions. Therefore, in-situ heater test was conducted in an underground cavern at a depth of 50 m for the purpose of improving thermo-hydro-mechanical coupled analysis code. This report presents the test result demonstrating the changes of temperature and strain distributions with time at the elevated temperature of the heater up to 90degC. (author)

  11. In-situ heating test in sedimentary soft rock. Phase 4

    International Nuclear Information System (INIS)

    Various researches have been conducted on high level radioactive waste geological disposal in sedimentary soft rocks. It is noted that the long-term mechanical behaviors of sedimentary soft rocks can be affected by various environmental factors such as temperatures or hydraulic conditions. Therefore, in-situ heating test was conducted in an underground cavern at a depth of 50 m for the purpose of improving thermo-hydro-mechanical coupled analysis code. This report presents the test result demonstrating the changes of temperature and strain with time at the elevated temperature of the heater up to 100degC. (author)

  12. Application of multiple tracer test for single fracture in sedimentary rock

    International Nuclear Information System (INIS)

    The evaluation of the advection-dispersion in the fracture and diffusion into the matrix from fracture is important to describe the mass transport processes in fractured porous media such as a sedimentary rock. However, it is often difficult to uniquely determine a number of parameters relevant to these phenomena, such as the fracture aperture, dispersivity coefficient, and matrix diffusion coefficient, from a data set of single tracer test. In this report, one-dimensional multiple tracer test for single fracture in a sedimentary rock block was conducted under the condition of injection rate for the unique parameter estimation suggested by authors. (author)

  13. Holocene shelf-coastal sedimentary systems associated with the Changjiang River:An overview

    Institute of Scientific and Technical Information of China (English)

    GAO Shu

    2013-01-01

    The fate of the terrestrial sediment supplied by rivers is a critical issue for understanding the patterns of Holocene environmental change on continental shelves. The East China Sea is a typical broad continental shelf with abundant sediment supply from large rivers. Here, a variety of sedimentary records were formed during the Holocene period. The sedimentary systems associated with these records have unique charac-teristics in terms of spatial distribution, material composition, deposition rate and the timing of deposition, which are related to active sediment transport processes induced by tides and waves, shelf circulations and sediment gravity flows. The sedimentary records thus formed are high resolution slices, i.e., each record has a temporal resolution of up to 100-10-1 a, but only covers a limited part of the Holocene time. In terms of the spatial distribution, these records are scattered over a large area on the shelf. Further studies of these systems are required to understand the underlying process-product relationships. In particular, the mid-Holocene coastal deposits on the Jiangsu coast, the early to middle Holocene sequences of the Hangzhou Bay, as well as the Holocene mud deposits off the Zhejiang-Fujian coasts, should be investigated in terms of the material supply (from both seabed reworking during the sea level rise event and river discharges), transport-accumulation processes, the sediment sequences and the future evolution of the sedimentary systems. Advanced numerical modeling techniques should be developed to meet the needs of these studies.

  14. SEDIMENTARY ORGANIC MATTER' S CLASSIFICATION OF OIL-GAS SOURCE ROCKS IN CHINA

    Institute of Scientific and Technical Information of China (English)

    JinKuili; LiuDameng; XiaoXianming

    1996-01-01

    According to the study on the oil-gas source rocks in China for ten years,in connection with the microscopic, submicroscopic levels, the authors used the microscope photometry together with transmission electronic microscopy, scanning electronic microscopy and proposed a new classification for Sedimentary organic matters.

  15. Seismic stratigraphy and sedimentary architecture of the Chalk Group in south-west Denmark

    DEFF Research Database (Denmark)

    Larsen, Connie; Ineson, Jon; Boldreel, Lars Ole

    2014-01-01

    The article focuses on a study undertaken by the Chalk Group on the western onshore region of the Danish Basin in Eastern Denmark related on the seismic stratigraphy and sedimentary architecture of the region. The study is undertaken through subdividing the northern North German Basin and the south...

  16. Persistent organic pollutants and sedimentary organic matter properties: A case study in the Kishon River, Israel

    International Nuclear Information System (INIS)

    The Kishon River, the second largest coastal river in Israel, has been severely polluted for several decades. Sediments from upstream and downstream sites of the river were analyzed, lipid-extracted and evaluated for phenanthrene uptake. Total polycyclic aromatic hydrocarbon (PAH) concentration in downstream sediments was 299 μg kg-1, consisting mostly of petrogenic-derived PAHs. Downstream sedimentary lipids were found to be dominated by fresh and decomposed petroleum-derived n-alkanes. The total PAH concentration in upstream sediments was 173 μg kg-1, consisting mostly of pyrogenic-derived PAHs, whereas lipids from these sediments were mostly vegetation-derived. Spectroscopic data suggested an exceptionally high aromatic content in downstream humic acid, which originated from PAHs attached to its structure. Sorption data suggested that upstream sedimentary cuticle-derived lipids function as a sorption domain, while downstream sedimentary lipids, consisting of shorter-chain-length petroleum-derived alkanes, compete with phenanthrene for sorption sites. - Petrogenic-derived xenobiotics affect the properties of sedimentary organic matter and its sorption capabilities

  17. Magnetic fabric in sedimentary rocks of acc retionary prisms and its modification by progressive ductile deformation

    Czech Academy of Sciences Publication Activity Database

    Hrouda, F.; Chadima, Martin

    Warshaw: Polish Geological Institute ; National research Institute, 2014 - (Sobien, K.; Roszkowska-Remin, J.; Baginska, A.; Dyrka, I.; Janas, M.). s. 21-21 ISBN 978-83-7863-381-5. [GeoShale 2014. 24.09.2014-26.09.2014, Warsaw] Keywords : magnetism * magnetic fabric * sedimentary rocks Subject RIV: DE - Earth Magnetism, Geodesy, Geography

  18. Geological heritage and high-school students : sedimentary aspects from SW Portugal

    OpenAIRE

    Balbino, Rita; Pimentel, N.; Brilha, J. B.

    2004-01-01

    The present work intends to expose the interesting sedimentary features which may be observed at the Sudoeste Alentejano e Costa Vicentina Natural Park, envisaging its use for one-day field-trips dedicated to high-school students, as well as for the general public.

  19. Influence of stress on the permeability of coal and sedimentary rocks of the Upper Silesian Basin

    Czech Academy of Sciences Publication Activity Database

    Konečný, Pavel; Kožušníková, Alena

    2011-01-01

    Roč. 48, č. 2 (2011), s. 347-352. ISSN 1365-1609 Institutional research plan: CEZ:AV0Z30860518 Keywords : permeability * triaxial test * coal and sedimentary rocks Subject RIV: DH - Mining, incl. Coal Mining Impact factor: 1.272, year: 2011 http://www.sciencedirect.com/science/article/pii/S1365160910002194

  20. Modeling of a sedimentary rock alternative for the siting of the radioactive waste disposal system

    International Nuclear Information System (INIS)

    Here are described the main concepts, the approximations, and all those simulation aspects that characterize the modeling performed using the unsaturated saturated approach for porous media. The objective of this work is to obtain a generic description of a sedimentary rock soil as an alternative site for the low and intermediate level radioactive waste disposal system. (author)

  1. The Potassic Sedimentary Rocks in Gale Crater, Mars, as Seen by ChemCam Onboard Curiosity.

    Science.gov (United States)

    Le Deit, Laetitia; Mangold, Nicolas; Forni, Olivier; Cousin, Agnes; Lasue, Jeremie; Schröder, Susanne; Wiens, Roger C.; Sumner, Dawn Y.; Fabre, Cecile; Stack, Katherine M.; Anderson, Ryan; Blaney, Diana L.; Clegg, Samuel M.; Dromart, Gilles; Fisk, Martin; Gasnault, Olivier; Grotzinger, John P.; Gupta, Sanjeev; Lanza, Nina; Le Mouélic, Stephane; Maurice, Sylvestre; McLennan, Scott M.; Meslin, Pierre-Yves; Nachon, Marion; Newsom, Horton E.; Payre, Valerie; Rapin, William; Rice, Melissa; Sautter, Violaine; Treiman, Alan H.

    2016-01-01

    The Mars Science Laboratory rover Curiosity encountered potassium-rich clastic sedimentary rocks at two sites in Gale Crater, the waypoints Cooperstown and Kimberley. These rocks include several distinct meters-thick sedimentary outcrops ranging from fine sandstone to conglomerate, interpreted to record an ancient fluvial or fluvio-deltaic depositional system (Grotzinger et al., 2015). From ChemCam LIBS chemical analyses, this suite of sedimentary rocks has an overall mean K2O abundance that is more than five times higher than that of the average Martian crust. The combined analysis of ChemCam data with stratigraphic and geographic locations reveals that the mean K2O abundance increases upward through the stratigraphic section. Chemical analyses across each unit can be represented as mixtures of several distinct chemical components, i.e. mineral phases, including K-bearing minerals, mafic silicates, Fe-oxides, and Fe-hydroxide/oxyhydroxides. Possible K-bearing minerals include alkali feldspar (including anorthoclase and sanidine) and K-bearing phyllosilicate such as illite. Mixtures of different source rocks, including a potassium-rich rock located on the rim and walls of Gale Crater are the likely origin of observed chemical variations within each unit. Physical sorting may have also played a role in the enrichment in K in the Kimberley formation. The occurrence of these potassic sedimentary rocks provides additional evidence for the chemical diversity of the crust exposed at Gale Crater.

  2. Sedimentary structures and facies interpretation of some molasse deposits : Sense- Schwarzwasser area, Canton Bern, Switzerland

    NARCIS (Netherlands)

    Linden, W.J.M. van der

    1963-01-01

    Burdigalian sand· and siltstones, belonging to the Upper Marine Molasse, have been studied in the Swiss "Mittel]and", to get an insight into the rela· tionships between primary sedimentary structures, their genesis and facies. To obtain information on the conditions, prevailing during the deposition

  3. Composition and sources of sedimentary organic matter in the deep Eastern Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    R. Pedrosa-Pàmies

    2015-07-01

    Full Text Available Surface sediments collected from deep slopes and basins (1018–4087 m depth of the oligotrophic Eastern Mediterranean Sea have been analysed for bulk elemental and isotopic composition of organic carbon, total nitrogen and selected lipid biomarkers, jointly with grain size distribution and other geochemical proxies. The distribution and sources of sedimentary organic matter (OM have been subsequently assessed and general environmental variables, such as water depth and currents, have been examined as causative factors of deep-sea sediment characteristics. Lithogenic and biogenic carbonates are the dominant sedimentary fractions, while both bulk and molecular organic tracers reflect a mixed contribution from autochthonous and allochthonous sources for the sedimentary OM, as indicated by relatively degraded marine OM, terrestrial plant waxes and anthropogenic OM including degraded petroleum by-products, respectively. Wide regional variations have been observed amongst the studied proxies, which reflect the multiple factors controlling sedimentation in the deep Eastern Mediterranean Sea. Our findings highlight the role of deep Eastern Mediterranean basins as depocentres of organic-rich fine-grained sediments (mean 5.4 ± 2.4 μm, with OM accumulation and burial due to aggregation mechanisms and hydrodynamic sorting. A multi-proxy approach is hired to investigate the biogeochemical composition of sediment samples, which sheds new light on the sources and transport mechanisms along with the impact of preservation vs. diagenetic processes on the composition of sedimentary OM in the deep basins of the oligotrophic Eastern Mediterranean Sea.

  4. Postseismic deformation and body forces shaping the Apennines and adjacent sedimentary basins in Umbria-Marche

    Directory of Open Access Journals (Sweden)

    A. Aoudia

    2008-06-01

    Full Text Available The geodynamic complexity of the Apennines and adjacent sedimentary basins in Umbria-Marche (North-Central Italy makes the dynamics of the present day deformation and its relationships with the seismicity less well understood. In this paper, we argue that, further to buoyancy forces, postseismic deformation of earthquakes taking place on the Apennines contributes to the regional deformation. We investigate the interaction between the normal faulting system responsible of the 1997 Umbria-Marche earthquake sequence (Colfiorito fault and the low angle normal faulting system bordering the sedimentary basins, namely the Altotiberina fault. We set-up a 2D finite element model of the lithosphere-asthenosphere accounting for lateral heterogeneities and investigate how this heterogeneous structure is capable of localizing strain under the Umbria-Marche sedimentary basins, providing a way for the Colfiorito fault to influence the evolution of the Altotiberina fault. We show how the two different length and time scale processes, namely postseismic deformation and buoyancy, are complementary in shaping the Apennines and adjacent sedimentary basins. The high resolution deformation patterns modeled in this study can hardly be reproduced by a model accounting only for external forces such as a rotating or subducting or retreating Adria.

  5. Thermal history of sedimentary basins of the Czech Republic and its relation to tectonic processes

    Czech Academy of Sciences Publication Activity Database

    Šafanda, Jan; Suchý, V.; Sýkorová, Ivana; Stejskal, M.; Filip, Jiří; Machovič, V.; Borecká, Lenka; Dobeš, P.

    11 (128) (2003), s. 45-54. ISSN 1212-1576 R&D Projects: GA AV ČR IAA3012703; GA AV ČR IBS3046004 Institutional research plan: CEZ:AV0Z3013912; CEZ:AV0Z3012916 Keywords : thermal history * tectonics * sedimentary basins Subject RIV: DC - Siesmology, Volcanology, Earth Structure

  6. Persistent organic pollutants and sedimentary organic matter properties: A case study in the Kishon River, Israel

    Energy Technology Data Exchange (ETDEWEB)

    Oren, Adi [Department of Soil and Water Sciences, Faculty of Agricultural, Food and Environmental Quality Sciences, Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100 (Israel); Aizenshtat, Zeev [Casali Institute of Applied Chemistry and Organic Chemistry, Hebrew University of Jerusalem, Jerusalem 91904 (Israel); Chefetz, Benny [Department of Soil and Water Sciences, Faculty of Agricultural, Food and Environmental Quality Sciences, Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100 (Israel)]. E-mail: chefetz@agri.huji.ac.il

    2006-05-15

    The Kishon River, the second largest coastal river in Israel, has been severely polluted for several decades. Sediments from upstream and downstream sites of the river were analyzed, lipid-extracted and evaluated for phenanthrene uptake. Total polycyclic aromatic hydrocarbon (PAH) concentration in downstream sediments was 299 {mu}g kg{sup -1}, consisting mostly of petrogenic-derived PAHs. Downstream sedimentary lipids were found to be dominated by fresh and decomposed petroleum-derived n-alkanes. The total PAH concentration in upstream sediments was 173 {mu}g kg{sup -1}, consisting mostly of pyrogenic-derived PAHs, whereas lipids from these sediments were mostly vegetation-derived. Spectroscopic data suggested an exceptionally high aromatic content in downstream humic acid, which originated from PAHs attached to its structure. Sorption data suggested that upstream sedimentary cuticle-derived lipids function as a sorption domain, while downstream sedimentary lipids, consisting of shorter-chain-length petroleum-derived alkanes, compete with phenanthrene for sorption sites. - Petrogenic-derived xenobiotics affect the properties of sedimentary organic matter and its sorption capabilities.

  7. 1.8 Billion Years of Detrital Zircon Recycling Calibrates a Refractory Part of Earth’s Sedimentary Cycle

    Science.gov (United States)

    Hadlari, Thomas; Swindles, Graeme T.; Galloway, Jennifer M.; Bell, Kimberley M.; Sulphur, Kyle C.; Heaman, Larry M.; Beranek, Luke P.; Fallas, Karen M.

    2015-01-01

    Detrital zircon studies are providing new insights on the evolution of sedimentary basins but the role of sedimentary recycling remains largely undefined. In a broad region of northwestern North America, this contribution traces the pathway of detrital zircon sand grains from Proterozoic sandstones through Phanerozoic strata and argues for multi-stage sedimentary recycling over more than a billion years. As a test of our hypothesis, integrated palynology and detrital zircon provenance provides clear evidence for erosion of Carboniferous strata in the northern Cordillera as a sediment source for Upper Cretaceous strata. Our results help to calibrate Earth's sedimentary cycle by showing that recycling dominates sedimentary provenance for the refractory mineral zircon. PMID:26658165

  8. Depositional features and sedimentary model of Buqu Stage in Mid-Jurassic in Qangtang Basin, Xizang (Tibet), China

    Institute of Scientific and Technical Information of China (English)

    WANG Xingtao; ZHAI Shikui; LIU Binde; ZHOU Shuxin

    2004-01-01

    The largest Mesozoic northward transgression in Qangtang Basin of Qinghai-Xizang (Tibet) Plateau occurred during the Buqu Stage, Middle Jurassic. Mainly filled with carbonate rocks, the whole basin is composed of transgression-regression sedimentary cycle. Field outcrops and indoor analysis revealed 8 types of sedimentary facies markers in this region. 4 types of sedimentary facies have been recognized: platform facies, platform marginal facies, foreslope facies and basin facies. Influenced by the northern Lazhuglung-Jinshajiang suture zone, central uplift region and southern Bangongco-Nujiang suture zone, these facies belts extended east-west. The sedimentary model was established based on observed depositional features. From their biological features and sedimentary characteristics, it is suggested that the paleoclimate was warm and humid at that time. The Buqu Formation is a promising target for oil and gas exploration in Shuanghu-Duoyong area in future.

  9. 1.8 Billion Years of Detrital Zircon Recycling Calibrates a Refractory Part of Earth's Sedimentary Cycle.

    Science.gov (United States)

    Hadlari, Thomas; Swindles, Graeme T; Galloway, Jennifer M; Bell, Kimberley M; Sulphur, Kyle C; Heaman, Larry M; Beranek, Luke P; Fallas, Karen M

    2015-01-01

    Detrital zircon studies are providing new insights on the evolution of sedimentary basins but the role of sedimentary recycling remains largely undefined. In a broad region of northwestern North America, this contribution traces the pathway of detrital zircon sand grains from Proterozoic sandstones through Phanerozoic strata and argues for multi-stage sedimentary recycling over more than a billion years. As a test of our hypothesis, integrated palynology and detrital zircon provenance provides clear evidence for erosion of Carboniferous strata in the northern Cordillera as a sediment source for Upper Cretaceous strata. Our results help to calibrate Earth's sedimentary cycle by showing that recycling dominates sedimentary provenance for the refractory mineral zircon. PMID:26658165

  10. Geoarchaeological investigations of a Mesolithic-Neolithic Sedimentary Sequence from Queens Sedgemoor, Somerset, UK

    Science.gov (United States)

    Hill, Tom; Whittaker, John; Brunning, Richard; Law, Matthew; Bell, Martin; Wilkinson, Keith

    2016-04-01

    A geoarchaeological investigation was undertaken at Queens Sedgemoor in Somerset, southwest England, as part of the English Heritage funded project 'the Mesolithic wetland/dryland edge in Somerset' (EH 6624). This project was designed to address the National Heritage Protection Plan (Topic 4G) associated with the assessment of the character and significance of sedimentary and wetland archaeology. As part of the project, a sediment core extracted from the site and has undergone high resolution radiocarbon dating, with subsequent detailed and directed micropalaeontological analyses (pollen, diatom, foraminifera, ostracoda, mollusca) focussing on the sedimentary sequence associated with the Mesolithic and early Neolithic periods. The presentation summarises the results of this multiproxy analyses and explains how it has assisted in understanding the landscape during a period of substantial prehistoric importance in southwest England. The sedimentary sequence dates back to the Mesolithic period (7.6ky BP) and the microfossil evidence indicates hydroseral succession has taken place, with the initial establishment of a freshwater lake, prior to undergoing terrestrialisation and the eventual development of a raised bog. Holocene sea-level change also influenced the sedimentary archive. Due to a rise in relative sea level c. 6.7ky BP, subsequent coastal inundation and estuarine sedimentation took also place and is hereby associated with the Lower Wentlooge Formation of the Somerset Levels. Although poor pollen preservation was encountered within the section specifically associated with the Mesolithic-Neolithic transition, a clear picture of landscape change is presented for the sedimentary archive, with evidence indicative of landscape modification by humans since the late Mesolithic.

  11. Fluvial geomorphic elements in modern sedimentary basins and their potential preservation in the rock record: A review

    Science.gov (United States)

    Weissmann, G. S.; Hartley, A. J.; Scuderi, L. A.; Nichols, G. J.; Owen, A.; Wright, S.; Felicia, A. L.; Holland, F.; Anaya, F. M. L.

    2015-12-01

    Since tectonic subsidence in sedimentary basins provides the potential for long-term facies preservation into the sedimentary record, analysis of geomorphic elements in modern continental sedimentary basins is required to understand facies relationships in sedimentary rocks. We use a database of over 700 modern sedimentary basins to characterize the fluvial geomorphology of sedimentary basins. Geomorphic elements were delineated in 10 representative sedimentary basins, focusing primarily on fluvial environments. Elements identified include distributive fluvial systems (DFS), tributive fluvial systems that occur between large DFS or in an axial position in the basin, lacustrine/playa, and eolian environments. The DFS elements include large DFS (> 30 km in length), small DFS (discharge through climatic variability or tectonic processes. We demonstrate that rivers on DFS commonly decrease in width down-DFS caused by infiltration, bifurcation, and evaporation. In proximal areas, channel sands are amalgamated through repeated avulsion, reoccupation of previous channel belts, and limited accumulation space. When rivers flood on the medial to distal portions of a DFS, the floodwaters spread across a large area on the DFS surface and typically do not re-enter the main channel. In these distal areas, rivers on DFS commonly avulse, leaving a discrete sand body and providing high preservation potential for floodplain deposits. Additional work is needed to evaluate the geomorphic character of modern sedimentary basins in order to construct improved facies models for the continental sedimentary rock record. Specifically, models for avulsion, bifurcation, infiltration, and geomorphic form on DFS are required to better define and subsequently predict facies geometries. Studies of fluvial systems in sedimentary basins are also important for evaluating flood patterns and groundwater distributions for populations in these regions.

  12. Aeolian sedimentary processes at the Bagnold Dunes, Mars: Implications for modern dune dynamics and sedimentary structures in the aeolian stratigraphic record of Mars

    Science.gov (United States)

    Ewing, Ryan C.; Bridges, Nathan T.; Sullivan, Rob; Lapotre, Mathieu G. A.; Fischer, Woodward W.; Lamb, Mike P.; Rubin, David M.; Lewis, Kevin W.; Gupta, Sanjeev

    2016-04-01

    Wind-blown sand dunes are ubiquitous on the surface of Mars and are a recognized component of the martian stratigraphic record. Our current knowledge of the aeolian sedimentary processes that determine dune morphology, drive dune dynamics, and create aeolian cross-stratification are based upon orbital studies of ripple and dune morphodynamics, rover observations of stratification on Mars, Earth analogs, and experimental and theoretical studies of sand movement under Martian conditions. In-situ observations of sand dunes (informally called the Bagnold Dunes) by Curiosity Rover in Gale Crater, Mars provide the first opportunity to make observations of dunes from the grain-to-dune scale thereby filling the gap in knowledge between theory and orbital observations and refining our understanding of the martian aeolian stratigraphic record. We use the suite of cameras on Curiosity, including Navigation Camera (Navcam), Mast Camera (Mastcam) and Mars Hand Lens Imager (MAHLI), to make observations of the Bagnold Dunes. Measurements of sedimentary structures are made where stereo images are available. Observations indicate that structures generated by gravity-driven processes on the dune lee slopes, such as grainflow and grainfall, are similar to the suite of aeolian sedimentary structures observed on Earth and should be present and recognizable in Mars' aeolian stratigraphic record. Structures formed by traction-driven processes deviate significantly from those found on Earth. The dune hosts centimeter-scale wind ripples and large, meter-scale ripples, which are not found on Earth. The large ripples migrate across the depositional, lee slopes of the dune, which implies that these structures should be present in Mars' stratigraphic record and may appear similar to compound-dune stratification.The Mars Science Laboratory Curiosity Rover Team is acknowledged for their support of this work.

  13. Geoengineering Research for a Deep Underground Science and Engineering Laboratory in Sedimentary Rock

    Science.gov (United States)

    Mauldon, M.

    2004-12-01

    A process to identify world-class research for a Deep Underground Science and Engineering Laboratory (DUSEL) in the USA has been initiated by NSF. While allowing physicists to study, inter alia, dark matter and dark energy, this laboratory will create unprecedented opportunities for biologists to study deep life, geoscientists to study crustal processes and geoengineers to study the behavior of rock, fluids and underground cavities at depth, on time scales of decades. A substantial portion of the nation's future infrastructure is likely to be sited underground because of energy costs, urban crowding and vulnerability of critical surface facilities. Economic and safe development of subsurface space will require an improved ability to engineer the geologic environment. Because of the prevalence of sedimentary rock in the upper continental crust, much of this subterranean infrastructure will be hosted in sedimentary rock. Sedimentary rocks are fundamentally anisotropic due to lithology and bedding, and to discontinuities ranging from microcracks to faults. Fractures, faults and bedding planes create structural defects and hydraulic pathways over a wide range of scales. Through experimentation, observation and monitoring in a sedimentary rock DUSEL, in conjunction with high performance computational models and visualization tools, we will explore the mechanical and hydraulic characteristics of layered rock. DUSEL will permit long-term experiments on 100 m blocks of rock in situ, accessed via peripheral tunnels. Rock volumes will be loaded to failure and monitored for post-peak behavior. The response of large rock bodies to stress relief-driven, time-dependent strain will be monitored over decades. Large block experiments will be aimed at measurement of fluid flow and particle/colloid transport, in situ mining (incl. mining with microbes), remediation technologies, fracture enhancement for resource extraction and large scale long-term rock mass response to induced

  14. Basin analysis and modeling of the burial, thermal and maturation histories in sedimentary basins

    Energy Technology Data Exchange (ETDEWEB)

    Makhous, M.; Galushkin, Y.

    2004-11-01

    This book is devoted to the field of basin analysis, and in particular to the one- and two-dimensional modeling of the burial, thermal and maturation histories of sedimentary basins, in the context of evaluating their hydrocarbon potential. A new modeling system is elaborated in this work and applied to continental basins. Particular attention is paid to specific features of basin evolution, including the compaction of sediments deposited at a variable rate, erosion of the sedimentary strata and basement, intrusive and hydrothermal activity, thermal activation and reactivation of the basement, lateral heat exchange of multiple-aged blocks of the oceanic and continental lithospheres, the jumping of spreading axes, etc. Alternative methods are applied for the control of tectonic subsidence, isostasy and rheology, lithosphere stretching and thinning. In order to evaluate their respective contributions to the thermal history of basins, a variety of situations are modeled, including spreading jumping, the evaluation of erosion heat, its impact on thermal history and links to pre- and post-sedimentation history, intrusion activity, and the formation and degradation of cryolitic zones (permafrost) in high-latitude basins of the Northern and Southern Hemispheres. A joint analysis of heat flow transfer in the sedimentary cover and the underlying lithosphere and asthenosphere is applied to better reconstruct their thermal and maturation histories. To further enhance the model's validity, an additional powerful control tool is applied, based on the coincidence of two calculations of tectonic curve subsidence of the basement surface, obtained by two independent approaches: back-stripping and temperature-dependant density distribution in the crust. This approach is also used to refine the simulation sequence for tectonic and thermal events in the history of sedimentary basins. Contents: 1. The Geodynamic Setting and Some Geomechanical Aspects of the Initiation and

  15. Three-dimensional sedimentary architecture of Quaternary deposits; a case study of environmental sedimentology (Bam, Iran)

    Science.gov (United States)

    Rezaei, K.; Guest, B.; Friedrich, A.; Fayazi, F.; Nakhaei, M.; Bakhtiari, H.; Nouri, L.

    2009-04-01

    Detailed 3-D analysis of the sedimentary structure and stratigraphy of these deposits allows for an accurate understand of sedimentary model of basin. This paper presents a case study in Bam (SE Iran) reconstructing the 3-D distribution of fluvial sediments based on a high resolution, process-orientated sedimentary facies classification and lithostratigraphy. We investigated the mean grain size with vertical and horizontal change of it, clay mineralogy, sediment texture, sedimentary structures, petrology and petrography and determination of paleo-environments and finally, we prepared two cross sections in S-N and W-E directions and a 3D block diagram for the situation of changes in subsurface sediments and compare them with the destruction rate map of earthquake in Bam city. Quaternary alluvial sediments are characterized by lithofacies deposited by braided river channels, debris flows and hyperconcentrated flows. The channel flow deposits constitute relatively well sorted, well imbricated and clast-supported gravels with coarse to medium sand matrix. Mostly poorly sorted, weakly imbricated to disorganized matrix supported pebble to boulder gravels with silty sand represent debris flow deposits. Hyperconcentrated flow deposits consist of clast-supported, poorly developed sorted polymodal gravel facies with poorly developed imbricated fabric, and generally occupy the lower parts of the terrace and fan sequences. The alternation from hyperconcentrated flow to channel flow deposits is predominant in the sequence, and is possibly the response to different climate modes. The high discharge and supply of sediments as well as the dispersal and deposition of these materials in the trunk stream is attributed to climatic perturbations during the Quaternary. These models allow quantifying the thickness and volume distribution of sandy gravel and clay deposits. We correlate these sedimentary units on the basis of lithofacies similarities, stratigraphic position. These

  16. Determining gamma dose rates by field gamma spectroscopy in sedimentary media: Results of Monte Carlo simulations

    International Nuclear Information System (INIS)

    Field gamma spectrometers are widely used to determine gamma dose rates in sedimentary media. However the most widely used technique-the 'window technique'-is time consuming and introduces important statistical uncertainty in the determination of the radioelement contents, and finally on the gamma dose rate. The threshold technique directly relates the number of counts recorded above certain threshold energy to the gamma dose rate. Recently new experimental measurements further investigated this technique but it has not been tested in various sedimentary media. In this paper, numerical simulations using a specifically designed Geant4 code allow to test the sensitivity of this technique to changes of sediments nature, humidity content and disequilibrium in the U-series. Finally another threshold technique, relating the gamma dose rate to the energy per unit time deposited above another threshold energy, is investigated. It is shown than the latter has a number of advantages compared to the classical techniques. Experimental results testing this approach are presented.

  17. Tectono-sedimentary processes at hyper-extended rifted margins: the Alpine and Pyrenean analogues

    Science.gov (United States)

    Masini, E.; Manatschal, G.; Mohn, G.; Tugend, J.

    2012-04-01

    The discovery of hyper-extended crust at deep-water rifted margins challenged the way of interpreting rifting and continental breakup. Indeed, syn-rift sedimentary basins, also referred to as either "supra-detachment basins" or "hyper-extended sag basins" are observed over thin hyper-extended crust that tapers oceanwards and is laterally replaced by exhumed subcontinental mantle. Studies performed off- and on-shore have shown that hyper-extended domains are formed by a complex interplay of exhumation faults leading to characteristic basin architectures. Despite of numerous interpretations of seismic sections across passive margins, the stratigraphic architecture of hyper-extended rift domains and their tectono-sedimentary evolution remain little understood. In this presentation, we present field-data from two well-preserved fossil hyper-extended domains exposed in the Alps and Pyrenees analogues that show some insights into the tectono-sedimentary evolution of hyper-extended rifted margins. Despite these two examples show a different sedimentary evolution, they exemplify how detachment systems can control accommodation space and sedimentary architecture. In both cases, the syn-rift sedimentary record can be studied in 3D allowing to evolutionary steps of supra-detachment basins to be identified. The study of these two field examples enables to identify key architectural elements of supra-detachment basins. These are detachment breakaway block and extensional allochthons, both controlling the first-order architecture of the basins. The former is the consequence of two successive low-angle detachment faults separated by a delaminated upper crustal block, whereas the latter results from the delamination of hanging-wall blocks and its emplacement over exhumed footwall. Exhumation along active detachment systems implies a very efficient creation of new real estate seafloor and results in a very specific stratigraphic record that includes from base to top: 1) a syn

  18. Tectono-sedimentary evolution of Erlian basin since late mesozoic and sandstone-hosted uranium metallogenesis

    International Nuclear Information System (INIS)

    Various mineral resources in a basin are associated with its tectono-sedimentary evolution. Based on the analysis of the tectono-sedimentary evolution of Erlian basin, three evolutional stages of Erlian basin are classified, they are: the continental extensional down-faulting stage, the transitional stage from down-faulting to down-warping in Early Cretaceous, and slightly compressional differentiated uplifting-subsidence since Late Cretaceous. According to the mechanism of sandstone-hosted uranium metallogenesis it is suggested that the grey clastic rock series deposited at the stage of down-faulting down-warping transition must be the important target for uranium prospecting, and the differentiated uplifting-subsidence offers necessary conditions for sandstone-hosted uranium ore-formation. Then, types of uranium mineralization that could occur in Erlian basin are discussed, and uranium metallogenic model has been preliminarily summarized. (authors)

  19. Evidence for only minor contributions from bacteria to sedimentary organic carbon

    Science.gov (United States)

    Hartgers, W. A.; Sinninghe Damste, J. S.; Requejo, A. G.; Allan, J.; Hayes, J. M.; de Leeuw, J. W.

    1994-01-01

    Because their molecular signatures are often prominent in extracts of sediments, bacteria are thought to be important contributors to petroleum source beds. It has been shown recently, however, that abundances of biomarkers do not always reflect relative contributions to sedimentary organic carbon (Corg). The contribution of photosynthetic green sulphur bacteria to sediments can be assessed effectively because the diagenetic products of distinctive carotenoids from these organisms occur widely and their biomass is isotopically labelled, being enriched in 13C. We show here that, although sediments and oils from the Western Canada and Williston basins contain prominent biomarkers of photosynthetic bacteria, the absence of 13C enrichment in the total Corg requires that the bacterial contribution is in fact minimal. Although the importance of bacterial reworking of sedimentary debris cannot be doubted, we argue that our findings, when considered in conjunction with those from other settings, suggest that bacterial biomass may commonly represent only a minor component of total Corg in carbonaceous rocks.

  20. Modeling of the Sedimentary Interbedded Basalt Stratigraphy for the Idaho National Laboratory Probabilistic Seismic Hazard Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Suzette Payne

    2007-08-01

    This report summarizes how the effects of the sedimentary interbedded basalt stratigraphy were modeled in the probabilistic seismic hazard analysis (PSHA) of the Idaho National Laboratory (INL). Drill holes indicate the bedrock beneath INL facilities is composed of about 1.1 km of alternating layers of basalt rock and loosely consolidated sediments. Alternating layers of hard rock and “soft” loose sediments tend to attenuate seismic energy greater than uniform rock due to scattering and damping. The INL PSHA incorporated the effects of the sedimentary interbedded basalt stratigraphy by developing site-specific shear (S) wave velocity profiles. The profiles were used in the PSHA to model the near-surface site response by developing site-specific stochastic attenuation relationships.

  1. Modeling of the Sedimentary Interbedded Basalt Stratigraphy for the Idaho National Laboratory Probabilistic Seismic Hazard Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Suzette Payne

    2006-04-01

    This report summarizes how the effects of the sedimentary interbedded basalt stratigraphy were modeled in the probabilistic seismic hazard analysis (PSHA) of the Idaho National Laboratory (INL). Drill holes indicate the bedrock beneath INL facilities is composed of about 1.1 km of alternating layers of basalt rock and loosely consolidated sediments. Alternating layers of hard rock and “soft” loose sediments tend to attenuate seismic energy greater than uniform rock due to scattering and damping. The INL PSHA incorporated the effects of the sedimentary interbedded basalt stratigraphy by developing site-specific shear (S) wave velocity profiles. The profiles were used in the PSHA to model the near-surface site response by developing site-specific stochastic attenuation relationships.

  2. Diffusion of 226Ra and 4K radionuclides reproduced in underwater sedimentary columns in laboratory

    International Nuclear Information System (INIS)

    The potential radiological impact of the increase of radioactive substances in the environment makes interesting the study of the migration of the contaminant radionuclides in soils and sediments, which are the last receiver system of these substances. By using a battery of sedimentary columns controlled in the laboratory, the diffusion of the 226Ra and 4K radionuclides has been studied, assessing their respective effective diffusion coefficients in a similar sedimentary medium. A decreasing temporal evolution is obtained, associated to the progressive 'fixation' of the radionuclides by the clay minerals of the sediment, followed by a constant tendency. A timescale of the 'fixation' by the sediment is determined, being of the order of days for 226Ra and of the order of months for 4K, so the progressive 'fixation' of 4K by the clay minerals of the sediments is slower than in the case of 226Ra

  3. X-ray diffraction analysis of clay stones, Muglad Sedimentary Basin, Sudan

    International Nuclear Information System (INIS)

    This study deals with the theoretical and experimental aspects of X-ray diffraction (XRD) technique. Moreover the XRD technique has been used to investigate the clay mineral types and their distribution for samples obtained from exploration wells in the Mugald Sedimentary Basin in Western Sudan. The studied samples range in depth from 1524 m to 4572 m. The XRD analysis of samples shows that they consist of kaolinite, smectite, illite, chlorite and the mixed-layer smectite/illite. Kaolinite has higher abundance (15 - 72 %) followed by illite (7 - 34 %), smectite (11 - 76 %) and the less abundance of chlorite and the mixed-layer smectite/illite. Non-clay minerals found include quartz and cristabolite. The clay mineral types and their vertical distribution reflect various controls such as environmental, burial diagenesis, source rocks and climatic influences in the Muglad Sedimentary Basin. (author). 19 refs., 11 figs., 3 tabs

  4. Sedimentary processes in Zenisu deep-sea channel revealed by side-scan imagery

    Science.gov (United States)

    Wu, Shiguo; Guo, Junhua; Hidekazu, Tokuyama

    2005-12-01

    Side-scan sonar data collected by Cruises 99-09 Leg 2 and 00-06 Leg 1 of R/V Yokosuka were used to reveal the sedimentary processes in Zenisu deep-sea channel. The middle and lower segments of the channel are rich in turbidite and other debrite deposits. By high-resolution imaging, three sedimentary processes were distinguished with distinct acoustic features. 1. Slumps and slides occur with contrasting backscatter, rough surface textures, blockings, and acoustic shadows at head walls. They are very extensive and often in lobate form downslope. 2. Debris flow has uniform, general medium backscatter, sometimes showing marbling/lineation in lobate form. 3. Turbidity current is characterized by low backscatter confined to the channel as acoustic signal is attenuated. Regional tectonics must be the dominating factor that controls deposition pattern in this area.

  5. Isotopic evidence of magmatism and a sedimentary carbon source at the Endeavour hydrothermal system

    Energy Technology Data Exchange (ETDEWEB)

    Brown, T A; Proskurowski, G; Lilley, M D

    2004-01-07

    Stable and radiocarbon isotope measurements made on CO{sub 2} from high temperature hydrothermal vents on the Endeavour Segment of the Juan de Fuca Ridge indicate both magmatic and sedimentary sources of carbon to the hydrothermal system. The Endeavour segment is devoid of overlying sediments and has shown no observable signs of surficial magmatic activity during the {approx}20 years of ongoing studies. The appearance of isotopically heavy, radiocarbon dead CO{sub 2} after a 1999 earthquake swarm requires that this earthquake event was magmatic in origin. Evidence for a sedimentary organic carbon source suggests the presence of buried sediments at the ridge axis. These findings, which represent the first temporally coherent set of radiocarbon measurements from hydrothermal vent fluids, demonstrate the utility of radiocarbon analysis in hydrothermal studies. The existence of a sediment source at Endeavour and the occurrence of magmatic episodes illustrate the extremely complex and evolving nature of the Endeavour hydrothermal system.

  6. Visualizing the sedimentary response through the orogenic cycle using multi-dimensional scaling

    Science.gov (United States)

    Spencer, C. J.; Kirkland, C.

    2015-12-01

    Changing patterns in detrital provenance through time have the ability to resolve salient features of an orogenic cycle. Such changes in the age spectrum of detrital minerals can be attributed to fluctuations in the geodynamic regime (e.g. opening of seaways, initiation of subduction and arc magmatism, and transition from subduction to collisional tectonics with arrival of exotic crustal material). These processes manifest themselves through a variety of sedimentary responses due to basin formation, transition from rift to drift sedimentation, or inversion and basement unroofing. This generally is charted by the presence of older detrital zircon populations during basement unroofing events and is followed by a successive younging in the detrital zircon age signature either through arrival of young island arc terranes or the progression of subduction magmatism along a continental margin. The sedimentary response to the aforementioned geodynamic environment can be visualized using a multi-dimensional scaling approach to detrital zircon age spectra. This statistical tool characterizes the "dissimilarity" of age spectra of the various sedimentary successions, but importantly also charts this measure through time. We present three case studies in which multi-dimensional scaling reveals additional useful information on the style of basin evolution within the orogenic cycle. The Albany-Fraser Orogeny in Western Australia and Grenville Orogeny (sensu stricto) in Laurentia demonstrate clear patterns in which detrital zircon age spectra become more dissimilar with time. In stark contrast, sedimentary successions from the Meso- to Neoproterozoic North Atlantic Region reveal no consistent pattern. Rather, the North Atlantic Region reflects a signature consistent with significant zircon age communication due to a distal position from an orogenic front, oblique translation of terranes, and complexity of the continental margin. This statistical approach provides a mechanism to

  7. Diatom preservation: differential preservation of sedimentary diatoms in two saline lakes

    OpenAIRE

    Flower, R. J.; D. B. Ryves

    2009-01-01

    The integrity of all sedimentary diatom assemblages is influenced to sonic degree by taphonomic processes. Recognising these processes with regard to preservation pathways for diatom assemblages and for individual species can be instructive for interpreting sediment core diatom records. Diatoms deposited in saline lakes are usually particularly exposed to both chemical and physical processes that promote poor preservation. Aspects of diatom preservation are explored in two markedly different ...

  8. Geophysical Estimation of Permeability in Sedimentary Media with Porosities from 0 to 50%

    OpenAIRE

    Díaz-Curiel Jesús; Biosca Bárbara; Miguel María Jesús

    2016-01-01

    The main objective of this study is to find a relationship between permeability and porosity, in the range 0 up to 50%, so that the permeability could be estimated only through geophysical parameters. This relationship should be consistent with the statistically expected values in sedimentary basins, and it should include the positive correlation between permeability and porosity in consolidated media and the negative correlation in unconsolidated ones. We have also developed another r...

  9. Petrography and sedimentology of Paleogene formations from Nathorstland, Spitsbergen: A diagenetic study of sedimentary facies associations

    OpenAIRE

    Vilberg, Anne Karin

    2011-01-01

    The studied Paleogene successions in the Central Basin Spitsbergen, comprises the Grumantbyen Formation, the Bjørnsonfjellet Member, Battfjellet Formation and the uppermost Aspelin toppen Formation. The objectives have been to describe the petrography and diagenesis relative to sedimentary facies associations. Another minor objective was to compare the reservoir quality of core and outcrop data. This have been done by description,facies interpretation and sampling from the Sysselmannsbreen co...

  10. Causes and Mechanisms of Remagnetisation in Palaeozoic Sedimentary Rocks - a Multidisciplinary Approach

    OpenAIRE

    Zwing, Alexander

    2003-01-01

    The present work combines palaeomagnetic and rock magnetic methods with clay mineralogy, isotope geochemistry of clay minerals and trace element geochemistry of Fe-oxide leachates to study remagnetised sedimentary rocks from Palaeozoic outcrops in Middle and Eastern Europe. Three areas were selected (NE Rhenish Massif, Barrandian and Holy Cross Mountains), where the causes of Late Palaeozoic remagnetisations are yet unclear. The results yield important implications for the processes and mecha...

  11. UAS-based quantification of sedimentary body changes at Langgriesgraben, Styria, Austria

    Science.gov (United States)

    Schöttl, Stefan; Seier, Gernot; Rascher, Eric; Sulzer, Wolfgang; Sass, Oliver

    2016-04-01

    The creek's sedimentary body at Langgriesgraben is characterized by inconstant but recurring earth surface changes. Mass transport and deposition occur partly spontaneously and endanger primary infrastructure, in particular a main road. It is often mentioned in literature that the use of small and lightweight UAS is promising. To contribute to that, this study focuses on the documentation and quantification of carried sedimentary material by using a hexacopter in a high alpine environment. The images which were captured on two different dates, allow generating orthophotos and DEMs. The comparison of these derivatives enables a deeper understanding of the sedimentary body and its conditions. Our specific study area is a part of a bigger research area of another research project (Sedyn-X). One of the main goals of that project is to create a conceptual model of the sedimentary cascade for the entire Johnsbachtal catchment and to quantify geomorphic processes (e.g. erosion, transport and rearrangement of sediments). Therefore Terrestrial Laser Scanning recordings are performed as well. Through the generated surface models from different eras, changes in surface and volume can be quantified. The photogrammetric surface models can be compared with almost simultaneous ALS and TLS recordings. Apart from that, the outcomes will provide hard facts for decision-makers. The UAS related processing steps and methods (e.g. DGPS, SfM) are more or less established and well-known, but the applicability of UAS for recording feasible data, has to be proved constantly. We assume that our results will answer concrete questions and thus reduce expected damage and costs.

  12. Nitrogen isotope dynamics and fractionation during sedimentary denitrification in Boknis Eck, Baltic Sea

    OpenAIRE

    Dähnke, K.; B. Thamdrup

    2013-01-01

    The global marine nitrogen cycle is constrained by nitrogen fixation as a source of reactive nitrogen, and denitrification or anammox on the sink side. These processes with their respective isotope effects set the marine nitrate 15N-isotope value (δ15N) to a relatively constant average of 5‰. This value can be used to better assess the magnitude of these sources and sink terms, but the underlying assumption is that sedimentary...

  13. Nitrogen isotope dynamics and fractionation during sedimentary denitrification in Boknis Eck, Baltic Sea

    OpenAIRE

    Dähnke, K.; B. Thamdrup

    2013-01-01

    The global marine nitrogen cycle is constrained by nitrogen fixation as a source of reactive nitrogen, and denitrification or anammox on the sink side. These processes with their respective isotope effects set the marine nitrate N-15-isotope value (delta N-15) to a relatively constant average of 5 parts per thousand. This value can be used to better assess the magnitude of these sources and sink terms, but the underlying assumption is that sedimentary denitrification and anammox, processes re...

  14. Engineering Geological Properties of Oil-Contaminated Granitic and Meta sedimentary Soils

    International Nuclear Information System (INIS)

    Hydrocarbon is a light-non aqueous phase liquid or known as LNAPL. It poses environmental hazard if accidentally spilled out into the soil and water systems as a result of its insoluble nature in water. LNAPL component infiltrates into soil through pore spaces and afloat at the top of groundwater level. Some of this hydrocarbon would trap and clog within the voids, difficult to remove and costly to clean. The occurrence of hydrocarbon in the soil definitely degraded the behaviour of soils in terms of engineering properties. This study aimed to investigate the engineering properties of oil-contaminated soil for two different residual soils originally developed from in-situ weathering of granitic and meta sedimentary rocks. The physical characterisations of the soil were determined including particle size distribution, specific gravity test and x-ray diffraction (XRD). The engineering parameters for the contaminated and uncontaminated soils were Atterberg limits, compaction and soil shear strength (UU tests). The amounts of hydrocarbon added to soil were varied at 0 %, 4 %, 8 %, 12 % and 16 % of dried weight of soil samples. The results from the particle size distribution analysis showed that residual soil from granitic rock comprises of 38 % sand, 33 % silt and 4 % clay while meta sedimentary soil consists of 4 % sand, 43 % silt dan 29 % clay. The mean values of specific gravity for the granitic and meta sedimentary soils were 2.56 and 2.61, respectively. The types of minerals present in granitic soil sample were quartz, kaolinite and gibbsite while meta sedimentary soil consists of quartz and kaolinite. The Atterberg limits value decreased as a result of increasing amount of added hydrocarbon into the soil. A similar behavior was observed with the values of maximum dry density and optimum water content with increasing hydrocarbon content. The overall unconsolidated undrained shear strength, Cu showed a decreasing trend with the increase in hydrocarbon content

  15. The Catalan margin during the Messinian Salinity Crisis: Physiography, morphology and sedimentary record

    OpenAIRE

    Garcia, Marga; Maillard, Agnès; Aslanian, Daniel; Rabineau, Marina; Alonso, Belén; Gorini, Christian; Estrada, Ferran

    2011-01-01

    The Messinian Salinity Crisis (MSC) drastically affected the physiography, morphology and sedimentation all along the Mediterranean area at the end of the Miocene. This paper presents an analysis of the effects of the MSC on the Catalan continental margin, based on a broad database of seismic reflection profiles from the oil industry and academy. We study the sedimentary processes and their controlling factors and the correlation with the nearby and well-known Gulf of Lions. Because of the co...

  16. Integrated geophysical and geological investigations applied to sedimentary rock mass characterization

    OpenAIRE

    S. Negri; Mazzone, F; Margiotta, S.; G. Leucci; M. T. Carrozzo

    2008-01-01

    The Salento Peninsula (south-eastern Italy) is characterized by sedimentary rocks. The carbonatic nature of the rocks means they are affected by karst phenomena, forming such features as sinkholes, collapsed dolines and caverns, as a result of chemical leaching of carbonates by percolating water. The instability of these phenomena often produces land subsidence problems. The importance of these events is increasing due to growing urbanization, numerous quarries affecting both the subsoil and ...

  17. Investigation of sedimentary aquifers in Denmark using the magnetic resonance sounding method (MRS)

    OpenAIRE

    Chalikakis, K.; Nielsen, M. R.; Legchenko, Anatoli; Hagensen, T. F.

    2009-01-01

    In order to evaluate the applicability of the magnetic resonance sounding method (MRS) in the Danish context and its accuracy in estimating the hydraulic conductivity of different sedimentary aquifers, three MRS campaigns were conducted in Denmark between 2003 and 2007. In total, 12 sites were investigated. At two sites, it was impossible to measure with MRS due to the high level of ambient electromagnetic noise. For the present study, MRS results from 10 investigated sites throughout Denmark...

  18. Biostratigraphy and sedimentary evolution of continental Neogene in the Madrid area

    OpenAIRE

    Alberdi Alonso, María Teresa; Hoyos Gómez, Manuel; Junco, Fernando; López Martínez, Nieves; Morales, Jorge; Sesé, Carmen; Soria, Dolores

    1984-01-01

    ABSTRACT: This is a study of the Lower and Middle Miocene in the area of Madrid. Sedimentation in this zone of the Tajo Basin corresponds to endorheic deposits fed by alluvial fans from the Sistema Central which, after transition facies, flow into the centre of the basin. Three sedimentary units can be distinguished throughout the distribution of these deposits: Lower, Intermediate and Upper. The base of the Lower Unit has been dated only by mammals fossils from drillings. It has been attribu...

  19. Magnetic properties of sedimentary greigite (Fe3S4): an update

    OpenAIRE

    Roberts, A. P.; Research School of Earth Sciences, Australian National University, Canberra, ACT, Australia; Chang, L.; National Oceanography Centre, Southampton, University of Southampton, Southampton, UK; Rowan, C. J.; School of GeoSciences, University of Edinburgh, Edinburgh, UK; Horng, C.; Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan; Florindo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia

    2010-01-01

    Greigite (Fe3S4) is an authigenic ferrimagnetic mineral that grows as a precursor to pyrite during early diagenetic sedimentary sulfate reduction. It can also grow at any time when dissolved iron and sulfide are available during diagenesis. Greigite is important in paleomagnetic, environmental, biological, biogeochemical, tectonic, and industrial processes. Much recent progress has been made in understanding its magnetic properties. Greigite is an inverse spinel and a collinear ferrimagnet...

  20. Magnetic properties of sedimentary greigite (Fe3S4): an update

    OpenAIRE

    Roberts, A. P.; National Oceanography Centre, University of Southampton, Southampton, UK.; Chang, L.; National Oceanography Centre, Southampton, University of Southampton, Southampton, UK; Rowan, C. J.; National Oceanography Centre, Southampton, University of Southampton, Southampton, UK and Now at School of GeoSciences, University of Edinburgh, Edinburgh, UK; Horng, C.‐S.; Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan; Florindo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia

    2011-01-01

    Greigite (Fe3S4) is an authigenic ferrimagnetic mineral that grows as a precursor to pyrite during early diagenetic sedimentary sulfate reduction. It can also grow at any time when dissolved iron and sulfide are available during diagenesis. Greigite is important in paleomagnetic, environmental, biological, biogeochemical, tectonic, and industrial processes. Much recent progress has been made in understanding its magnetic properties. Greigite is an inverse spinel and a col...

  1. Sorption and diffusion of Eu in sedimentary rock in the presence of humic substance

    International Nuclear Information System (INIS)

    Sorption and diffusion behaviors of Eu in sedimentary rock in the presence of humic substance were investigated. The sedimentary rock collected from 500 m depth of HDB-6 bore hole at horonobe URL site of Japan and Aldrich humic acid (HA) were used in the present study. Sorption behaviors of Eu and the HA on the sedimentary rocks with and without the rock organic matter (ROM) were elucidated as a function of HA concentration. The HA reduced the sorption of Eu on the rock with the increase of HA. Eu and HA sorption on the rock with the ROM was larger than on the rock after removing the ROM, indicating that the ROM plays an important role on the sorption of Eu and HA. The diffusion of Eu in the presence of HA was examined as a function of HA concentration and molecular weight of the HA (∝ 150 kDa or below 10 kDa) by means of a reservoir depletion test method with the intact rock core of the sedimentary rock. Depletion of Eu concentration in the reservoir was reduced with the increase of HA concentration. On the other hand, slight depletion of HA concentration in the reservoir was observed, indicating that the larger HA molecule diffused less into the rock. From the depletion curve and indiffusion profile of Eu in the rock, the effective diffusion coefficient, De, and distribution coefficient, Kd, in the intact system were estimated based on the profile fitting of the diffusion data with the conventional simple diffusion-sorption model. It was elucidated that the HA reduced the Kd and De of Eu in the intact system with the increase of HA. The contribution of the HA with smaller molecular weight to both the Eu sorption and diffusion was examined. (orig.)

  2. Baseline Scotland : groundwater chemistry of the Carboniferous sedimentary aquifers of the Midland Valley

    OpenAIRE

    O Dochartaigh, B.E.; Smedley, P. L.; MacDonald, A.M.; Darling, W. G.; Homoncik, S.

    2011-01-01

    This report describes the baseline groundwater chemistry of the sedimentary aquifers of Carboniferous age in the Midland Valley of Scotland. Groundwater is an important resource in the Midland Valley, largely for agriculture, but also for industry – including food and drink processing and mineral water bottling, and for domestic use. A large but unquantified volume of groundwater is also still pumped from former mine workings, largely coal mines, in order to maintain water levels and for qual...

  3. Modelling depositional shifts between sedimentary basins: Sediment pathways in Paratethys basins during the Messinian Salinity Crisis

    OpenAIRE

    J. Bartol; L. Matenco; D. Garcia-Castellanos; K. Leever

    2012-01-01

    The evolution of sedimentary basins separated by uplifted topographic barriers is characterised by gradual regressive deposition until one of the basins is filled and its sedimentation bypasses to the adjacent basin, defining a depositional shift. One of the critical parameters controlling these depositional shifts is sea level variation, its drop potentially triggering a depositional shift by cancelling the available accommodation space. Conversely, a sea level rise can create new accommodat...

  4. Composition and sources of sedimentary organic matter in the deep eastern Mediterranean Sea

    Science.gov (United States)

    Pedrosa-Pàmies, R.; Parinos, C.; Sanchez-Vidal, A.; Gogou, A.; Calafat, A.; Canals, M.; Bouloubassi, I.; Lampadariou, N.

    2015-12-01

    Surface sediments collected from deep slopes and basins (1018-4087 m depth) of the oligotrophic eastern Mediterranean Sea have been analysed for bulk elemental and isotopic composition of organic carbon, total nitrogen and selected lipid biomarkers, jointly with grain size distribution and other geochemical proxies. The distribution and sources of sedimentary organic matter (OM) have been subsequently assessed and general environmental variables, such as water column depth and physical circulation patterns, have been examined as causative factors of deep-sea sediment characteristics. Lithogenic and biogenic carbonates are the dominant sedimentary fractions, accounting for up to 85.4 and 66.5 % of the total weight respectively. The low OC and TN contents in the surface sediments of the study area, which ranged from 0.15 to 1.15 % and 0.06 to 0.11 % respectively, reflect the oligotrophic character of the eastern Mediterranean Sea. Both bulk and molecular organic tracers reflect a mixed contribution from autochthonous and allochthonous sources for the sedimentary OM, as indicated by relatively degraded marine OM, terrestrial plant waxes and anthropogenic OM (e.g. degraded petroleum by-products) respectively. Wide regional variations have been observed amongst the studied proxies, which reflect the multiple factors controlling sedimentation in the deep eastern Mediterranean Sea. Our findings highlight the role of deep eastern Mediterranean basins as depocentres of organic-rich fine-grained sediments (mean 5.4 ± 2.4 μm), with OM accumulation and burial being attributed to aggregation mechanisms and hydrodynamic sorting. A multi-proxy approach is applied aiming to investigate the biogeochemical composition of sediment samples, which sheds new light on the sources and transport mechanisms along with the impact of preservation vs. diagenetic processes on the composition of sedimentary OM in the deep basins of the oligotrophic eastern Mediterranean Sea.

  5. Peculiarities of the Earth's crust sedimentary layer structure in the Falkland Basin

    Science.gov (United States)

    Schreider, A. A.; Mazo, E. L.; Bulychev, A. A.; Kulikova, M. P.; Gilod, D. A.; Schreider, Al. A.; Boiko, A. N.

    2010-12-01

    An electronic databank including the results of seismic investigations and schemes of the sediment thickness's distribution patterns was built up for two seismostratigraphic complexes in the Falkland Basin. The interface's border was dated, and the sedimentation rates were estimated for each complex. An integrated map of the cumulative thickness of the deposits and sedimentation rates was developed. The lowest limits of the parameters of the sedimentation process were characterized for the sedimentary layers affected by compaction and erosion.

  6. Integrated geophysical and geological investigations applied to sedimentary rock mass characterization

    Directory of Open Access Journals (Sweden)

    S. Negri

    2008-06-01

    Full Text Available The Salento Peninsula (south-eastern Italy is characterized by sedimentary rocks. The carbonatic nature of the rocks means they are affected by karst phenomena, forming such features as sinkholes, collapsed dolines and caverns, as a result of chemical leaching of carbonates by percolating water. The instability of these phenomena often produces land subsidence problems. The importance of these events is increasing due to growing urbanization, numerous quarries affecting both the subsoil and the surface, and an important coastline characterized by cliffs. This paper focuses on geological and geophysical methods for the characterization of soft sedimentary rock, and presents the results of a study carried out in an urban area of Salento. Taking the Q system derived by Barton (2002 as the starting point for the rock mass classification, a new approach and a modification of the Barton method are proposed. The new equation proposed for the classification of sedimentary rock mass (Qsrm takes account of the permeability of the rock masses, the geometry of the exposed rock face and their types (for example, quarry face, coastal cliff or cavity, the nature of the lithotypes that constitute the exposed sequence, and their structure and texture. This study revises the correlation between Vp and Q derived by Barton (2002, deriving a new empirical equation correlating P-wave velocities and Qsrm values in soft sedimentary rock. We also present a case history in which stratigraphical surveys, Electrical Resistivity Tomography (ERT, and seismic surveys were applied to in situ investigations of subsidence phenomena in an urban area to estimate rock mass quality. Our work shows that in the analysis of ground safety it is important to establish the rock mass quality of the subsurface structures; geophysical exploration can thus play a key role in the assessment of subsidence risk.

  7. Sedimentary record of mid-Miocene seismotectonic activity in the Sinop Peninsula, north-central Turkey

    OpenAIRE

    Ayhan ILGAR

    2014-01-01

    The middle Miocene shallow-marine siliciclastic succession in the Sinop Peninsula, north-central Turkey, bears a well-preserved sedimentary record of syndepositional deformation associated with the buried escarpment of an oblique-slip dextral reverse fault and attributed to seismotectonic activity. The deposition occurred in a marginal trough at the edge of a tectonically inverted retroarc foreland basin of the Central Pontides. The synsedimentary deformation involved contemporaneous shorefac...

  8. Elemental Geochemistry of Sedimentary Rocks at Yellowknife Bay, Gale Crater, Mars

    OpenAIRE

    McLennan, S. M.; Anderson, R. B.; Bell, J. F., III; Bridges, J. C.; Calef, F., III; Campbell, John L.; Clark, B. C.; Clegg, S.; Conrad, P.; Cousin, A.; Des Marais, D J; Dromart, G.; Dyar, M. D.; Edgar, L. A.; Ehlmann, B. L.

    2014-01-01

    Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from approximately average Martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved indicating arid, possibly cold, paleoclimates and rapid erosion/deposition. Absence of predicted geochemical variations indicates that magnetite and phyllosilicates formed by diagenesis under low temperature, circum-neutral pH, rock-dominat...

  9. The problems of Paleozoic beds and reconstruction of the Middle Permian sedimentary basin in western Slovenia

    OpenAIRE

    Ivan Mlakar

    2003-01-01

    In the first part of paper geologic data from smaller outcrops of Val Gardena Formation in west Slovenia are assembled. Together with the already published information from larger outcrops they permit the reconstruction of the Middle Permian sedimentary basin on which the accent of paper is based. Attention is drawn to general problems of Upper Paleozoic beds, and conclusions regarding lithologic, stratigraphic and structural control of uranium and copper deposits in this part of Slovenia are...

  10. The problems of Paleozoic beds and reconstruction of the Middle Permian sedimentary basin in western Slovenia

    Directory of Open Access Journals (Sweden)

    Ivan Mlakar

    2003-06-01

    Full Text Available In the first part of paper geologic data from smaller outcrops of Val Gardena Formation in west Slovenia are assembled. Together with the already published information from larger outcrops they permit the reconstruction of the Middle Permian sedimentary basin on which the accent of paper is based. Attention is drawn to general problems of Upper Paleozoic beds, and conclusions regarding lithologic, stratigraphic and structural control of uranium and copper deposits in this part of Slovenia are given.

  11. Integrated techniques to evaluate the features of sedimentary rocks of archaeological areas of Sicily

    Directory of Open Access Journals (Sweden)

    Maria Brai

    2004-02-01

    Full Text Available Sicily includes a great variety of lithologies, giving a high complexity to the geologic landscape. Their prevalent lithology is sedimentary. It is well known that rocks of sedimentary origin, compared with metamorphic and volcanic deposits, can be relatively soft and hence fairly easy to model. Nevertheless, this workability advantage is a drawback for Cultural Heritage applications. In fact, these materials show a high porosity, with pore-size distributions that lead to deterioration through absorption of water. In this paper, several sedimentary rocks used in historical Cultural Heritage items of Sicily, from "Magna Graecia" to nowadays, are classified for mineralogical features, chemical composition, and for porosity. Particularly, some samples collected in quarries relevant to the archaeological sites of 41 Agrigento, Segesta and Selinunte will be considered and characterized using integrated techniques (XRD, XRF, NMR and CT. Data on samples obtained in laboratory will be compared with the relevant values measured in situ on monuments of historical-cultural interest of the quoted archaeological places.

  12. Advanced Horizontal Well Recirculation Systems for Geothermal Energy Recovery in Sedimentary and Crystalline Formations

    Energy Technology Data Exchange (ETDEWEB)

    Bruno, Mike S. [Terralog Technologies USA, Inc., Calgary (Canada); Detwiler, Russell L. [Terralog Technologies USA, Inc., Calgary (Canada); Lao, Kang [Terralog Technologies USA, Inc., Calgary (Canada); Serajian, Vahid [Terralog Technologies USA, Inc., Calgary (Canada); Elkhoury, Jean [Terralog Technologies USA, Inc., Calgary (Canada); Diessl, Julia [Terralog Technologies USA, Inc., Calgary (Canada); White, Nicky [Terralog Technologies USA, Inc., Calgary (Canada)

    2012-12-13

    There is increased recognition that geothermal energy resources are more widespread than previously thought, with potential for providing a significant amount of sustainable clean energy worldwide. Recent advances in drilling, completion, and production technology from the oil and gas industry can now be applied to unlock vast new geothermal resources, with some estimates for potential electricity generation from geothermal energy now on the order of 2 million megawatts. The primary objectives of this DOE research effort are to develop and document optimum design configurations and operating practices to produce geothermal power from hot permeable sedimentary and crystalline formations using advanced horizontal well recirculation systems. During Phase I of this research project Terralog Technologies USA and The University of California, Irvine (UCI), have completed preliminary investigations and documentation of advanced design concepts for paired horizontal well recirculation systems, optimally configured for geothermal energy recovery in permeable sedimentary and crystalline formations of varying structure and material properties. We have also identified significant geologic resources appropriate for application of such technology. The main challenge for such recirculation systems is to optimize both the design configuration and the operating practices for cost-effective geothermal energy recovery. These will be strongly influenced by sedimentary formation properties, including thickness and dip, temperature, thermal conductivity, heat capacity, permeability, and porosity; and by working fluid properties.

  13. On the sedimentological origin of down-core variations of bulk sedimentary nitrogen isotope ratios

    Science.gov (United States)

    Kienast, M.; Higginson, M. J.; Mollenhauer, G.; Eglinton, T. I.; Chen, M.-T.; Calvert, S. E.

    2005-06-01

    The bulk sedimentary nitrogen isotopic composition of two cores from nearby sites on the northern slope of the South China Sea (Site 17940 and Ocean Drilling Program (ODP) Site 1144) differs by up to >2‰ during the last glacial period. Given their close proximity, both core sites are located in the same biogeographic zone and nutrient regime, and it is thus unlikely that this offset is due to a true gradient in surface ocean conditions. In an attempt to resolve this offset, we have investigated the possible effects of two sedimentological parameters that can affect bulk sedimentary δ15N, namely, the variable contribution of inorganic N to bulk N in the sediment and the grain-size dependence of bulk δ15N. We find that neither effect, singly or in combination, is sufficient to explain the significant δ15N offset between the two down-core records. By elimination the most likely explanation for the observed discrepancy is a different origin of both the organic and inorganic nitrogen at each site. This study adds to the growing body of evidence highlighting the complex nature and origin of the sedimentary components in sediment drifts, such as ODP Site 1144.

  14. CSPG - SEPM joint convention : Program with abstracts - Sedimentary events and hydrocarbon systems

    International Nuclear Information System (INIS)

    This joint conference of the Canadian Society of Petroleum Geologists (CSPG) and the Society for Sedimentary Geology (SEPM) was held in Calgary, to encourage collaboration between the petroleum resource industry and academia. Well over 150 papers were presented in various special sessions. The principal topics of discussion included examination, investigation and assessment of the geology, geophysics, geochemistry and the resource potential of sedimentary basins in Canada and around the world. In the course of the presentations the depositional, tectonic and diagenetic histories of various formations, augmented with interpretations of the origin and evolution of the basins were reviewed. The new interpretations were made possible by the new concepts and models of sedimentary geoscience that were born in the creative cauldron of collaboration that exists between industry, government institutions and the universities. The widespread use of modern sequence stratigraphy was used as an example of how scientific and engineering synergy evolved over time to shed new light on the nature of the stratigraphic record. Environmental issues regarding the petroleum industry also received much attention. This volume contains the complete conference program listing, a list of the sponsors and exhibitors, and provides brief abstracts of all papers presented at the conference

  15. Spatial stochastic modeling of sedimentary formations to assess CO2 storage potential.

    Science.gov (United States)

    Popova, Olga H; Small, Mitchell J; McCoy, Sean T; Thomas, A C; Rose, Stephen; Karimi, Bobak; Carter, Kristin; Goodman, Angela

    2014-06-01

    Carbon capture and sequestration (CCS) is a technology that provides a near-term solution to reduce anthropogenic CO2 emissions to the atmosphere and reduce our impact on the climate system. Assessments of carbon sequestration resources that have been made for North America using existing methodologies likely underestimate uncertainty and variability in the reservoir parameters. This paper describes a geostatistical model developed to estimate the CO2 storage resource in sedimentary formations. The proposed stochastic model accounts for the spatial distribution of reservoir properties and is implemented in a case study of the Oriskany Formation of the Appalachian sedimentary basin. Results indicate that the CO2 storage resource for the Pennsylvania part of the Oriskany Formation has substantial spatial variation due to heterogeneity of formation properties and basin geology leading to significant uncertainty in the storage assessment. The Oriskany Formation sequestration resource estimate in Pennsylvania calculated with the effective efficiency factor, E=5%, ranges from 0.15 to 1.01 gigatonnes (Gt) with a mean value of 0.52 Gt of CO2 (E=5%). The methodology is generalizable to other sedimentary formations in which site-specific trend analyses and statistical models are developed to estimate the CO2 sequestration storage capacity and its uncertainty. More precise CO2 storage resource estimates will provide better recommendations for government and industry leaders and inform their decisions on which greenhouse gas mitigation measures are best fit for their regions. PMID:24824160

  16. Sedimentary history and economic geology of San Juan Basin, New Mexico and Colorado

    International Nuclear Information System (INIS)

    The San Juan Basin contains up to 15,000 ft of sedimentary rocks ranging in age from Cambrian to Recent. The earliest development of the area as a sedimentary basin or trough apparently took place in Pennsylvanian time, and the basin was maintained, with changing rates of subsidence and filling, through the remainder of geologic time. During the Early Paleozoic, sedimentation was dominated by marine transgressions across the northwestern flank of the regional Transcontinental Arch. The Late Paleozoic history was strongly influenced by tectonism related to development of the Ancestral Rocky Mountains Uplifts and associated downwarping. The Early Mesozoic is characterized by fluvial and eolian environments, interrupted periodically by thin marine transgressive deposits of nearshore redbeds. The final Mesozoic event was the widespread Late Cretaceous marine transgression which deposited a thick cyclic sequence of marine gray shale and sandstone, with interbedded coal. Late Tertiary regional uplift and resulting volcanism were accompanied by a regional dissection of the area by stream systems that evolved into the present drainage pattern of superposed streams. The sedimentary history is directly related to the occurrence of economic deposits in the basin. Major reserves of petroleum and gas are in Cretaceous and Pennsylvanian rocks, coal in Cretaceous, and uranium in Jurassic and Cretaceous. Abstract only

  17. Factors influencing the biogeochemistry of sedimentary carbon and phosphorus in the Sacramento-San Joaquin Delta

    Science.gov (United States)

    Nilsen, E.B.; Delaney, M.L.

    2005-01-01

    This study characterizes organic carbon (Corganic) and phosphorus (P) geochemistry in surface sediments of the Sacramento-San Joaquin Delta, California. Sediment cores were collected from five sites on a sample transect from the edge of the San Francisco Bay eastward to the freshwater Consumnes River. The top 8 cm of each core were analyzed (in 1-cm intervals) for Corganic, four P fractions, and redox-sensitive trace metals (uranium and manganese). Sedimentary Corganic concentrations and Corganic:P ratios decreased, while reactive P concentrations increased moving inland in the Delta. The fraction of total P represented by organic P increased inland, while that of authigenic P was higher bayward than inland reflecting increased diagenetic alteration of organic matter toward the bayward end of the transect. The redox indicator metals are consistent with decreasing sedimentary suboxia inland. The distribution of P fractions and C:P ratios reflect the presence of relatively labile organic matter in upstream surface sediments. Sediment C and P geochemistry is influenced by site-specific particulate organic matter sources, the sorptive power of the sedimentary material present, physical forcing, and early diagenetic transformations presumably driven by Corganic oxidation. ?? 2005 Estuarine Research Federation.

  18. Identification of a late Quaternary alluvial-aeolian sedimentary sequence in the Sichuan Basin, China

    Science.gov (United States)

    Feng, Jin-Liang; Ju, Jian-Ting; Chen, Feng; Hu, Zhao-Guo; Zhao, Xiang; Gao, Shao-Peng

    2016-03-01

    The late Quaternary sedimentary sequence in the northwestern part of the Sichuan Basin consists of five lithological units and with increasing depth include the: Chengdu Clay; Brown Clay; Red Clay; Sandy Silt; and basal Muddy Gravel. The genesis, provenance and age of the sediments, as well as the possible presence of hiatuses within this sequence are debated. Measurements of grain-size, magnetic susceptibility, quartz content, quartz δ18O values, element composition, and Sr-Nd isotopic concentrations of samples from a typical sedimentary sequence in the area provides new insights into the genesis and history of the sequence. The new data confirm that the sediments in study site are alluvial-aeolian in origin, with basal alluvial deposits overlain by aeolian deposits. Like the uppermost Chengdu Clay, the underlying Brown Clay and Red Clay are aeolian in origin. In contrast, the Silty Sand, like the basal Muddy Gravel, is an alluvial deposit and not an aeolian deposit as previously thought. Moreover, the succession of the aeolian deposits very likely contains two significant sedimentary hiatuses. Sedimentological analysis demonstrates that the source materials for the aeolian deposits in the northwestern part of the Sichuan Basin and those on the eastern Tibetan Plateau are different. Furthermore, the loess deposits on the eastern Tibetan Plateau are derived from heterogeneous local sources.

  19. Landform assemblages and sedimentary processes along the Norwegian Channel Ice Stream

    Science.gov (United States)

    Ottesen, Dag; Stokes, Chris R.; Bøe, Reidulv; Rise, Leif; Longva, Oddvar; Thorsnes, Terje; Olesen, Odleiv; Bugge, Tom; Lepland, Aave; Hestvik, Ole B.

    2016-06-01

    Several regional and detailed bathymetric datasets together with 2D and 3D seismic data are compiled to investigate the landform assemblages and sedimentary processes along the former path of the Norwegian Channel Ice Stream (NCIS). At the broad scale, the glacial geomorphology and sedimentary architecture reveals three different zones along the ice-stream path, characterized by: (1) glacial erosion in the onset zone and inner shelf area, (2) sediment transport through the main trunk of the ice stream across the mid-shelf, and (3) a zone of deposition towards the outer continental shelf edge. Along the first 400 km of the ice stream bed (outer Oslofjord-Skagerrak-Stavanger) a major overdeepening is associated with suites of crag-and-tail features at the transition from the crystalline bedrock to the sedimentary bedrock, together with evidence of glaciotectonic thrusting in the form of hill-hole pairs. Here we interpret extensive erosion of both sedimentary rocks and Quaternary sediments. This zone is succeeded by an approximately 400 km long zone, through which most of the sediments eroded from the inner shelf were transported, rather than being deposited. We infer that sediment was transported subglacially and is likely to have been advected downstream by soft sediment deformation. The thickness of till of inferred Weichselian age generally varies from 0 and 50 m and this zone is characterized by mega-scale glacial lineations (MSGLs) which we interpret to be formed in a dynamic sedimentary system dominated by high sediment fluxes, but with some localized sediment accretion associated with lineations. Towards the shelf break, the North Sea Fan extends to the deep Norwegian Sea, and reflects massive sedimentation of glacigenic debris onto the continental slope. Numerous glacigenic debris flows accumulated and constructed a unit up to 400 m thick during the Last Glacial Maximum. The presence of these three zones (erosion, transport, deposition) is consistent with

  20. Recording of climate and diagenesis through sedimentary DNA and fossil pigments at Laguna Potrok Aike, Argentina

    Science.gov (United States)

    Vuillemin, Aurèle; Ariztegui, Daniel; Leavitt, Peter R.; Bunting, Lynda; The Pasado Science Team

    2016-04-01

    Aquatic sediments record past climatic conditions while providing a wide range of ecological niches for microorganisms. In theory, benthic microbial community composition should depend on environmental features and geochemical conditions of surrounding sediments, as well as ontogeny of the subsurface environment as sediment degraded. In principle, DNA in sediments should be composed of ancient and extant microbial elements persisting at different degrees of preservation, although to date few studies have quantified the relative influence of each factor in regulating final composition of total sedimentary DNA assemblage. Here geomicrobiological and phylogenetic analyses of a Patagonian maar lake were used to indicate that the different sedimentary microbial assemblages derive from specific lacustrine regimes during defined climatic periods. Two climatic intervals (Mid-Holocene, 5 ka BP; Last Glacial Maximum, 25 ka BP) whose sediments harbored active microbial populations were sampled for a comparative environmental study based on fossil pigments and 16S rRNA gene sequences. The genetic assemblage recovered from the Holocene record revealed a microbial community displaying metabolic complementarities that allowed prolonged degradation of organic matter to methane. The series of Archaea identified throughout the Holocene record indicated an age-related stratification of these populations brought on by environmental selection during early diagenesis. These characteristics were associated with sediments resulting from endorheic lake conditions and stable pelagic regime, high evaporative stress and concomitant high algal productivity. In contrast, sulphate-reducing bacteria and lithotrophic Archaea were predominant in sediments dated from the Last Glacial Maximum, in which pelagic clays alternated with fine volcanic material characteristic of a lake level highstand and freshwater conditions, but reduced water column productivity. Comparison of sedimentary DNA composition

  1. In-situ Micro-structural Studies of Gas Hydrate Formation in Sedimentary Matrices

    Science.gov (United States)

    Kuhs, Werner F.; Chaouachi, Marwen; Falenty, Andrzej; Sell, Kathleen; Schwarz, Jens-Oliver; Wolf, Martin; Enzmann, Frieder; Kersten, Michael; Haberthür, David

    2015-04-01

    The formation process of gas hydrates in sedimentary matrices is of crucial importance for the physical and transport properties of the resulting aggregates. This process has never been observed in-situ with sub-micron resolution. Here, we report on synchrotron-based micro-tomographic studies by which the nucleation and growth processes of gas hydrate were observed in different sedimentary matrices (natural quartz, glass beds with different surface properties, with and without admixtures of kaolinite and montmorillonite) at varying water saturation. The nucleation sites can be easily identified and the growth pattern is clearly established. In under-saturated sediments the nucleation starts at the water-gas interface and proceeds from there to form predominantly isometric single crystals of 10-20μm size. Using a newly developed synchrotron-based method we have determined the crystallite size distributions (CSD) of the gas hydrate in the sedimentary matrix confirming in a quantitative and statistically relevant manner the impressions from the tomographic reconstructions. It is noteworthy that the CSDs from synthetic hydrates are distinctly smaller than those of natural gas hydrates [1], which suggest that coarsening processes take place in the sedimentary matrix after the initial hydrate formation. Understanding the processes of formation and coarsening may eventually permit the determination of the age of gas hydrates in sedimentary matrices [2], which are largely unknown at present. Furthermore, the full micro-structural picture and its evolution will enable quantitative digital rock physics modeling to reveal poroelastic properties and in this way to support the exploration and exploitation of gas hydrate resources in the future. [1] Klapp S.A., Hemes S., Klein H., Bohrmann G., McDonald I., Kuhs W.F. Grain size measurements of natural gas hydrates. Marine Geology 2010; 274(1-4):85-94. [2] Klapp S.A., Klein H, Kuhs W.F. First determination of gas hydrate

  2. Characterizing the Biological and Geochemical Architecture of Hydrothermally Derived Sedimentary Deposits: Coupling Micro Raman Spectroscopy with Noble Gas Spectrometry

    Science.gov (United States)

    Bower, D. M.; Conrad, P. G.; Steele, A.; Fries, M. D.

    2016-05-01

    The chemical species in cherts and glass fragments were analyzed using micro Raman spectroscopy in conjunction with measurements of heavy noble gas isotopes to characterize hydrothermally derived sedimentary environments.

  3. Description and hydrogeologic implications of cored sedimentary material from the 1975 drilling program at the Radioactive Waste Management Complex, Idaho

    International Nuclear Information System (INIS)

    Samples of sedimentary material from interbeds between basalt flows and from fractures in the flows, taken from two drill cores at the Radioactive Waste Management Complex at the Idaho National Engineering Laboratory were analyzed for (1) particle-size distribution, (2) bulk mineralogy, (3) clay mineralogy, (4) cation-exchange capacity, and (5) carbonate content. Thin sections of selected sedimentary material were made for petrographic examination. These analyses are needed for a characterization of paths and rates of movement of radionuclides transported by infiltrating water. Preliminary interpretations indicate that (1) it may be possible to distinguish the various sedimentary interbeds on the basis of their mineralogy, (2) the presence of carbonate horizons in sedimentary interbeds may be utilized to approximate the time of exposure and the climate while the surface was exposed, and (3) the type and orientation of fracture-filling material may be utilized to determine the mechanism by which fractures were filled. 9 references, 14 figures, 8 tables

  4. Dissolved particulate and sedimentary humic acids in the mangroves and estuarine ecosystem of Goa, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Sardessai, S.

    Highest concentration of humic acids in all the three forms (dissolved, particulate and sedimentary) was found in the monsoon (June-September) when the salinity was minimum while the lowest concentrations was observed in the premonsoon (February...

  5. SEDIMENTARY PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>20111628 Bao Hanyong(State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China);Han Guangmin Clay Mineral Analysis of the Early Triassic Tempestites,Lower Yangtze Region(Journal of Jilin University,ISSN1671-5888,CN22-1343/P,40(4),2010,p.947-954,5 illus.,1 table,19 refs.,with English abstract)Key words:tempestite deposit,clay minerals,Yangtze Region

  6. SEDIMENTARY PETROLOGY

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>20080229 Bai Guoping(Key Laboratory for Hydrocarbon Accumulation of Education Ministry,China University of Petroleum,Beijing 102249,China);John B.Keene Diagenesis and Fluid Flow History in Sandstones of the Upper Permian Black Jack Formation,Gunnedah Basin,Eastern Australia(Acta Geologica Sinica(English Edition)--Journal of the Geological Society of China,ISSN1000-9515,CN11-2001/P,81(3),2007,p.433-441,5 illus.,3 tables,21 refs.) Key words:sandstone,Australia

  7. What is the tectono-sedimentary record of hyper-extended, magma-poor rifted margins ?

    Science.gov (United States)

    Masini, Emmanuel; Manatschal, Gianreto; Mohn, Geoffroy; Lafont, François; Jammes, Suzon; Geoffroy, Laurent; Robin, Cécile

    2010-05-01

    The tectono-sedimentary record of hyper-extended, deep-water rifted margins is yet poorly understood due to the limited access to direct observations. The study of fossil analogues shows that the major change from low strain (e.g. North Sea) to high-strain rift systems is controlled by the occurrence of low-angle detachment systems associated with extensional allochthons. In such systems classical syn- to post-rift sedimentary models cannot be directly applied because the depositional geometries, the creation of space as well as the relation to potential sources are different. In our study we investigate the tectono-sedimentary record of high strain, hyper-extended deep-water rifted margins. We studied a present-day and two fossil hyper-extended rift systems, which preserve detachment systems that control the syn- to post-rift sedimentary record. The three examples are: (1) The SE Alpine Tethys (AT) rifted margin preserved in SE Switzerland. (2) The Mauléon basin in the Western Pyrenees (WP) (3) The southeastern termination of the Baja California peninsula in the Gulf of California (GC) representing a subactual system. For all three examples rift related detachment structures and their relations to pre-, syn-, and post-rift sediments can be mapped. Despite of the different plate kinematic settings (orthogonal (AT), segmented (WP), transtensional (GC)), sediment supply (starved (AT) vs. rich (WP, GC), and facies (marine (AT, WP) vs. subareal (GC)), the overall tectono-sedimentary evolution shows strong similarities and can be described as following. The detachment faulting is recorded by the generation of extensional allochthons derived from the delamination of the former hanging-wall. These syn-tectonic sediments show the progressive switch from hanging-wall to footwall derived lithologies. The sourcing change reflects the exhumation and formation of top-basement detachment systems. Sediments related to this stage represent poorly organized locally-derived tectono-sedimentary

  8. Sedimentary dykes in the Oskarshamn-Vaestervik area. A study of the mechanism of formation

    International Nuclear Information System (INIS)

    This study of the sedimentary dykes from the Oskarshamn-Vaestervik area, near Aespoe and surrounding region, is aimed at understanding the mechanism of their formation. In particular it is important to establish whether or not they formed by the injection of high pressure fluidized sediments and if so what the likely effect of any future over pressured sediments will be on the stability of the fracture network in the basement rocks at Aespoe. This report is made up of a review of the literature on sedimentary dykes, a discussion of the various mechanical models for hydraulic fracturing and a description of the field and laboratory study carried out on the sedimentary dykes. The literature review indicates a remarkable consensus on the mode of formation of these structures based on their fabric (particularly layering generated in part by variation in clast size) and the composition of the infilling material. Two modes of origin have been recognised. These are the passive infilling of dykes where the dyke material has entered an open fracture under the influence of gravity, and active, i.e. forceful injection of a fluidized sediment under high pressure into a pre-existing fracture or into a fracture generated by the high pressure fluid. The discussion of the theory of fluid induced fracturing leads to the recognition of three systems which are the two end members and an intermediate form of a complete spectrum of materials ranging from unconsolidated and incohesive sediments, through cemented but porous rocks to crystalline rocks with no intrinsic porosity and whose only porosity relates to that imparted by the fracture network that the rock contains. The theory best suited to analyses this latter system is one based on fracture mechanics and is known as the theory of external hydraulic fracturing. From the point of view of the sedimentary dykes in the study area around the Aespoe Hard Rock Laboratory, where the dykes occur in the fractured granitic basement, this is

  9. Sedimentary dykes in the Oskarshamn-Vaestervik area. A study of the mechanism of formation

    Energy Technology Data Exchange (ETDEWEB)

    Roeshoff, Kennert [BBK AB, Solna (Sweden); Cosgrove, John [Imperial College, London (United Kingdom). Dept. of Earth Sciences and Engineering

    2002-07-01

    This study of the sedimentary dykes from the Oskarshamn-Vaestervik area, near Aespoe and surrounding region, is aimed at understanding the mechanism of their formation. In particular it is important to establish whether or not they formed by the injection of high pressure fluidized sediments and if so what the likely effect of any future over pressured sediments will be on the stability of the fracture network in the basement rocks at Aespoe. This report is made up of a review of the literature on sedimentary dykes, a discussion of the various mechanical models for hydraulic fracturing and a description of the field and laboratory study carried out on the sedimentary dykes. The literature review indicates a remarkable consensus on the mode of formation of these structures based on their fabric (particularly layering generated in part by variation in clast size) and the composition of the infilling material. Two modes of origin have been recognised. These are the passive infilling of dykes where the dyke material has entered an open fracture under the influence of gravity, and active, i.e. forceful injection of a fluidized sediment under high pressure into a pre-existing fracture or into a fracture generated by the high pressure fluid. The discussion of the theory of fluid induced fracturing leads to the recognition of three systems which are the two end members and an intermediate form of a complete spectrum of materials ranging from unconsolidated and incohesive sediments, through cemented but porous rocks to crystalline rocks with no intrinsic porosity and whose only porosity relates to that imparted by the fracture network that the rock contains. The theory best suited to analyses this latter system is one based on fracture mechanics and is known as the theory of external hydraulic fracturing. From the point of view of the sedimentary dykes in the study area around the Aespoe Hard Rock Laboratory, where the dykes occur in the fractured granitic basement, this is

  10. Tectonic and climatic control of the changes in the sedimentary record of the Karnali River section (Siwaliks of western Nepal).

    OpenAIRE

    Huyghe, P.; Mugnier, J. L.; Gajurel, A.P.; Delcaillau, B.

    2005-01-01

    A multidisciplinary study was conducted on the section of the Siwalik Group sediments, approximately 5000 m thick, exposed along the Karnali River. Analysis of facies, clay mineralogy and neodymium isotope compositions revealed significant changes in the sedimentary record, allowing discussion of their tectonic or climatic origin. Two major changes within the sedimentary fill were detected: the change from a meandering to a braided river system at ca 9.5 Ma and the change from a deep sandy br...

  11. Temporal variability in the biochemical composition of sedimentary organic matter in an intertidal flat of the Galician coast (NW Spain)

    OpenAIRE

    Cividanes, S; Incera, M.; Lopez, J

    2002-01-01

    Temporal variations and spatial distribution of sedimentary organic matter composition were investigated over a one year period in an intertidal flat of the NW Spain. Sediment samples were collected from 0 to 25 cm depth, every three months, from January 1997 to January 1998 at three tidal levels (high, medium and low). Changes in the elemental and biochemical composition were assessed to gather information on temporal and spatial fluctuations in quantity and quality of sedimentary organic ma...

  12. Sedimentary Facies Models on Carbonatite in the Upper Shuaiba Member of Lower Cretaceous in Daleel Field, Oman

    Institute of Scientific and Technical Information of China (English)

    Wang Feng; Jiang Zaixing; Zhou Liqing; Zhao Guoliang; Wang Lin; Zheng Ning; Xiang Shu'an

    2007-01-01

    The Upper Shuaiba Member (USH) is the main force pay bed in the Daleel field in northern Oman; 5 layers including A, B, C, D, and E were divided in profile, and layer D and layer E are the main beds. With the development of exploration in the Daieel oil field, studying the sedimentary systems about their inner composition and the collocation in dimension, and setting up the sedimentary models in the USH are becoming more and more necessary and important to meet the further exploration requirement. Based on the data of geology, seism, and paleo-biology, according to the analysis method on carbonatite depositional system, the litho-facies assemblage and sedimentary environment in the USH were studied. Intershoal low-lying sub-facies (where the water depth is 10-50 m) and shallow shoal sub-facies (where the water depth is not more than 10 m) were extinguished in the layer D, and storm deposit was found in layer E1, in which intershoal low-lying sub-facies also developed. The feature of the sedimentary sub-facies and the sedimentary condition were analyzed, and the sedimentary model was set up in the article: the carbonatite intershoal low-lying developed under the background of open land in shallow sea, where storm events usually occurred in the Lower Cretaceous in the area.

  13. Results from the geological surveys carried out in the Bure laboratory's drifts

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. After the government's authorization to build and operate an underground laboratory, Andra started the investigation works in November 99 on the Meuse/Haute-Marne URL site. The Meuse/Haute-Marne URL is located at the border of the Champagne-Ardenne and Lorraine regions, on the township of Bure in the Callovo-Oxfordian clay-rich rock. At this place, the layer is about 135 m-thick and lies at a depth of 417 m to 552 m. The construction of the underground installations started in August 2000 with the sinking of the main shaft and the first phase of diggings was completed on the 27 April 2006 when it linked up with the south drift of the laboratory. The laboratory consists in two vertical shafts crossing the 505-m thick sedimentary cover and two levels of experimental drifts dug in Callovo-Oxfordian formation. The first experimental drift dug at -445 m with a drill-and-blast method with steps of 2.4 m. The technical and experimental drifts at the main level (-490 m of depth) were dug with a hydraulic stone crusher. The aims of the geological surveys carried out during the drifts digging are to observe the lateral variation of the lithology, if there is one, to confirm the absence of fault and the geometry of the argillites formation. These works should also allow to characterize the natural or inducted fracturing (EDZ - Excavation Damaged Zone) induced by the digging by a sedimentary and structural follow-up. The EDZ characterization has been established from the geological survey of the drift face and sidewalls carried out from 1 to 5 meters in the drifts, and completed by the structural analysis of the cores of the boreholes drilled for the experimentations' equipments. After the safe keeping of the front, the geological team goes down to carry out the survey which consists in a lithologic and sedimentary mapping, a structural survey for the understanding of joints distribution and EDZ characterization, and

  14. Shelf-edge sedimentary systems off Rio de Janeiro State, northern Santos basin-Brazil

    Science.gov (United States)

    Maia, R. M. C.; Dos Reis, A. T.; Gorini, C.; Silva, C. G.; Rabineau, M.; Granjeon, D.

    2012-04-01

    The sedimentary record of the continental shelf off Rio de Janeiro State is related to the opening and evolution of Atlantic Ocean. The combined analysis of high resolution seismic acquired in the early 80's (Geomar cruises) and 2D seismic lines of petroleum industry, coupled with chronostratigraphic data from oil industry's exploratory wells, allowed us to observe two different orders of sequences: of 3-4th order, that represents sedimentary units related of the Milankovitch cycles (100/40/20ky), and of 2nd order (10-100my). High resolution seismic allowed us to outline a first architectural framework for the actual shelf that is composed of stacked seismic units making up the major seismic sequences bounded by angular unconformities. According to the intern and extern configuration of their clinoforms, the seismic sequences were grouped into two distinctive stratigraphic sets, identified as Set I (Pliocene) and Set II (Upper Quaternary). Some architectural components of note include: (1) the characteristic upbuilt-outbuilt geometry of sequences that compose Set I (SqA, SqB and SqC), indicating that deposition has probably been favoured by a combination of prevailing subsidence regime (upbuilt pattern) accompanied by forced regressive deposits (outbuilt pattern); (2) the majority of sequences that make up Set II outbuilts as a composite seaward-thickening progradational wedge formed under dominant forced regression conditions, implying that the generation of accommodation space was less important than during the build-up of Set I. However, these sequences consistently pinch out in a progressively landward direction, suggesting a prevailing and increasing subsidence regime able to induce the progressive seaward tilting of the margin during the middle-late Pleistocene, and the subsequent partial preservation of regressive sequences of about 100-200 m thick at the level of the present-day mid-shelf, that prograded seaward for circa 15-25 km. These architectural

  15. Recent benthic foraminifera and sedimentary facies distribution of the Abu Dhabi (United Arab Emirates) coastline

    Science.gov (United States)

    Fiorini, Flavia; Lokier, Stephen W.

    2014-05-01

    The distribution of benthic foraminifera and sedimentary facies from Recent coastline environments adjacent to the coastline of Abu Dhabi (UAE) was studied in detail with the aim to: 1) provide reliable analogs for understanding and interpreting the depositional environment of ancient shallow-marine sediments from the UAE; 2) assess any modifications in the distribution of benthic environments and sedimentary facies in an area affected by significant anthropogenic activities - particular construction and land reclamation. A total of 100 sea-floor sediment samples were collected in different shallow-marine sedimentary environments (nearshore shelf, beach-front, channels, ooid shoals, lagoon and mangals) close to the coastline of Abu Dhabi Island. Where possible, we revisited the sampling sites used in several studies conducted in the middle of last century (prior to any significant anthropogenic activities) to assess temporal changes in Recent benthic foraminifera and sedimentary facies distribution during the last 50 years. Five foraminiferal assemblages were recognized in the studied area. Species with a porcellaneous test mainly belonging to the genera Quinqueloculina, Triloculina, Spiroloculina, Sigmoilinita are common in all studied areas. Larger benthic foraminifera Peneroplis and Spirolina are particularly abundant in samples collected on seaweed. Hyaline foraminifera mostly belonging to the genera Elphidium, Ammonia, Bolivina and Rosalina are also common together with Miliolidae in the nearshore shelf and beach front. Agglutinated foraminifera (Clavulina, Textularia, Ammobaculites and Reophax) are present in low percentages. The species belonging to the genera Ammobaculites and Reophax are present only in the finest grain samples particularly in lagoons and mangal environments and have not been reported previously in the studied area. The majority of the ooid shoal sediments, the coarser sediments of the beach-front and samples collected in dredged channels

  16. Gestures and metaphors as indicators of conceptual understanding of sedimentary systems

    Science.gov (United States)

    Riggs, E. M.; Herrera, J. S.

    2012-12-01

    Understanding the geometry and evolution of sedimentary systems and sequence stratigraphy is crucial to the development of geoscientists and engineers working in the petroleum industry. There is a wide variety of audiences within industry who require relatively advanced instruction in this area of geoscience, and there is an equally wide array of approaches to teaching this material in the classroom and field. This research was undertaken to develop a clearer picture of how conceptual understanding in this area of sedimentary geology grows as a result of instruction and how instructors can monitor the completeness and accuracy of student thinking and mental models. We sought ways to assess understanding that did not rely on model-specific jargon but rather was based in physical expression of basic processes and attributes of sedimentary systems. Advances in cognitive science and educational research indicate that a significant part of spatial cognition is facilitated by gesture, (e.g. giving directions, describing objects or landscape features). We aligned the analysis of gestures with conceptual metaphor theory to probe the use of mental image-schemas as a source of concept representation for students' learning of sedimentary processes. In order to explore image schemas that lie in student explanations, we focused our analysis on four core ideas about sedimentary systems that involve sea level change and sediment deposition, namely relative sea level, base level, and sea-level fluctuations and resulting basin geometry and sediment deposition changes. The study included 25 students from three U.S. Midwestern universities. Undergraduate and graduate-level participants were enrolled in senior-level undergraduate courses in sedimentology and stratigraphy. We used semi-structured interviews and videotaping for data collection. We coded the data to focus on deictic, iconic, and metaphoric gestures, and coded interview transcripts for linguistic metaphors using the

  17. Sedimentary dynamics modelling for the radionuclides transfer in the water stream

    International Nuclear Information System (INIS)

    At the 'Institute of Radioprotection and Nuclear Safety', IRSN, where the present work has been performed, one of the main activities is the development of radionuclide transfer models into the environment (water, soil, plants etc...). Taking into account the sedimentary dynamics when modeling aquatic environment transfers and its real influence on the radioecological impact is the present work main objective. Our work confirms the necessity to take into account the sedimentary dynamics when studying the radioecological impact of the power plants release in the water stream. In this context, we first developed, after the bibliographic study, a multi-class radioecological water quality model (the TRACE code) and we proposed experimental protocols to determine the required parameters for erosion and deposition fluxes. For each experiment, an associated model was developed for calibration. An application of the global model (TRACE) to the Bas Rhone Languedoc channel (BRL) shows good agreement between all the parameters introduced in the code and the in site measurements performed to quantify the bottom sediment activity. It is not sufficient to consider a global approach of the sedimentary dynamics, because we showed explicitly that the multi lass approach provides better agreement with the experimental results. Our work opens future prospects that could be explored for its continuation, of which we can raise the main ones. It will be interesting to repeat all the experiments at different stages of the year and for different charges of the Rhone; To apply this study to estuaries or lakes, when the bottom geometry is not uniform like that of the BRL channel, TRACE could be extended to two dimensions in space. (author)

  18. Adjoint-tomography Inversion of the Small-scale Surface Sedimentary Structures: Key Methodological Aspects

    Science.gov (United States)

    Kubina, Filip; Moczo, Peter; Kristek, Jozef; Michlik, Filip

    2016-04-01

    Adjoint tomography has proven an irreplaceable useful tool in exploring Earth's structure in the regional and global scales. It has not been widely applied for improving models of local surface sedimentary structures (LSSS) in numerical predictions of earthquake ground motion (EGM). Anomalous earthquake motions and corresponding damage in earthquakes are often due to site effects in local surface sedimentary basins. Because majority of world population is located atop surface sedimentary basins, it is important to predict EGM at these sites during future earthquakes. A major lesson learned from dedicated international tests focused on numerical prediction of EGM in LSSS is that it is hard to reach better agreement between data and synthetics without an improved structural model. If earthquake records are available for sites atop a LSSS it is natural to consider them for improving the structural model. Computationally efficient adjoint tomography might be a proper tool. A seismic wavefield in LSSS is relatively very complex due to diffractions, conversions, interference and often also resonant phenomena. In shallow basins, the first arrivals are not suitable for inversion due to almost vertical incidence and thus insufficient vertical resolution. Later wavefield consists mostly of local surface waves often without separated wave groups. Consequently, computed kernels are complicated and not suitable for inversion without pre-processing. The spatial complexity of a kernel can be dramatic in a typical situation with relatively low number of sources (local earthquakes) and surface receivers. This complexity can be simplified by directionally-dependent smoothing and spatially-dependent normalization that condition reasonable convergence. A multiscale approach seems necessary given the usual difference between the available and true models. Interestingly, only a successive inversion of μ and λ elastic moduli, and different scale sequences lead to good results.

  19. Historical eutrophication in the Changjiang and Mississippi delta-front estuaries: Stable sedimentary chloropigments as biomarkers

    Science.gov (United States)

    Zhao, Jun; Bianchi, Thomas S.; Li, Xinxin; Allison, Mead A.; Yao, Peng; Yu, Zhigang

    2012-09-01

    Eutrophication is one of the most significant ecological problems in large-river delta-front estuaries (LDEs) around the world. We used TOC, TN, δ13C, δ15N and three stable sedimentary chloropigments (pyropheophytin-a [pPHtin-a], sterol chlorin esters [SCEs] and carotenol chlorin esters [CCEs]) as geochemical proxies to examine historical trends of eutrophication over the last few decades in the Changjiang and Mississippi LDEs. Concentrations of sedimentary pPHtin-a, SCEs and CCEs increased from 15, 12 and 120 nmol g-1 OC in 1960s to 51, 32 and 256 nmol g-1 OC in 1990s on the inner shelf of the East China Sea, respectively, and from 57, 69 and 31 nmol g-1 OC in 1950s to 70, 90 and 44 nmol g-1 OC in 2000s in the Mississippi Canyon, respectively. Riverine loading of DIN flux to LDE increased from (261±109)×106 kg yr-1 in pre-1980 to (1385±209)×106 kg yr-1 in post-1990 in the Changjiang LDE, while nitrate flux increased from (322±89)×106 kg yr-1 in the 1950s to 1960s to (589±123)×106 kg yr-1 in the 1970s, and DIN flux kept relatively stable in (963±250)×106 kg yr-1 from the 1980s to 2000s in the Mississippi LDE. This work reveals that the stable sedimentary chloropigments in accumulating sediments on the inner shelf are suitable biomarkers for examining past changes in eutrophication in the Changjiang and Mississippi LDE ecosystems. The historical record of riverine nutrient inputs as related to changes in the watershed (e.g., fertilizers and manure) is well-correlated with down-core concentrations of stable pheopigment biomarkers in sediments at both LDEs. These results support the coupling between enhanced phytoplankton abundance and increasing anthropogenic nutrients input to the inner shelves of these LDEs.

  20. Linking margin morphology to sedimentary processes along the US East Coast passive continental margin

    Science.gov (United States)

    Brothers, D. S.; ten Brink, U. S.; Andrews, B.; Twichell, D.

    2010-12-01

    The morphology of the US East Coast continental slope and rise has a surprising amount of along-margin variation. Multibeam bathymetry datasets that cover the slope and rise from Cape Hatteras to Georges Bank provide a unique opportunity to analyze both first-order and higher-order morphologies, including submarine canyons, landslides, slumps and sedimentary bedforms. Using the morphological characterization coupled with seismic and core data, we hope to better understand how ancient and modern sedimentary processes control the shape of the margin. As a first step, the margin bathymetry was subdivided into 20 shelf-perpendicular regions from which several statistical parameters were analyzed. Within each region, the slope gradient was computed separately for down-slope and across-slope aspect directions. Distribution curves in each region for down- and across-slope gradients and seafloor roughness as functions of depth were grouped according to their statistical similarities. Four basic groups emerge and each approximately corresponds to known regions of Quaternary glacial, fluvial, current-controlled and gravity-driven sedimentary transport. In the second part of the study, published lithologic and chronostratigraphic frameworks of this margin were used to examine the relationship between seafloor morphology and the underlying geology. Along the upper continental rise, thick Quaternary deposits appear to have a strong influence on the short- and long-wavelength variation in rise topography, revealing a complex interplay between down-slope and along-slope sediment transport. Despite the close correlation between continental slope morphology and Quaternary environmental conditions, initial results suggest that the underlying, older, stratigraphy also plays a primary role. Along the continental slope, Quaternary processes appear to control the relief of slope-confined canyons and other short-wavelength (Tertiary and older material.

  1. [Over one hundred year sedimentary record of polycyclic aromatic hydrocarbons in the Andaman Sea, Malaysia].

    Science.gov (United States)

    Wu, Yu-Ling; Wang, Xin-Hong; Li, Yong-Yu; Hong, Hua-Sheng; Li, He-Yang; Yin, Ming-Duan

    2009-09-15

    Polycyclic aromatic hydrocarbons (PAHs) in a sediment core collected from Langkawi Island of the Andaman Sea, Malaysia were determined by GC/MS, the vertical variations of concentration and distributions of PAHs were investigated. In combining with 210Pb-dating, the PAHs sedimentary record in the last 100 years was reconstructed and their possible sources were also discussed. The sigmaPAH concentration ranged from 13.2-60.1 ng x g(-1) in the whole sedimentary section (0-56 cm) with the dominant compounds of phenanthrene, naphthalene and perylene. The sediments contaminated to a lesser extent comparing with the surrounding waters. Before the 1920s, the concentrations of PAHs were considered to be the background level, which was implied from the natural inputs. The historical records of PAHs in the core showed that two distinct peaks which represented the input time of 1960s and 1980s, respectively, inferred that there were some relatively dramatically land-based inputs, and human activities leaded a clear impact to these waters during these periods. Furthermore, PAHs diagnostic ratios indicated that PAHs in the core sediments were mainly of pyrolytic origin (combustion), accompanied with minor petroleum origin. These were related with agriculture, industry, ocean import and export, and shipping activities in the surrounding regions. Meanwhile as the vital communication line, the marine transportation of the Strait of Malacca had influenced the environmental quality of the Andaman Sea. Meanwhile, based on the sedimentary record, PAHs concentrations were found to correlate positively with humanism activities and socioeconomic development (Gross Domestic Production) in the surrounding regions. PMID:19927796

  2. The Hidden Watershed's Journals: the Informational Characteristics of Biomarkers in Sedimentary Deposits

    Science.gov (United States)

    Guerrero, F. J.; Hatten, J. A.

    2014-12-01

    The historical reconstruction of past environmental changes in watersheds is essential to understand watershed response to disturbances and how those diturbances could affect the provision of valuable goods like water. That reconstruction requires the interpretation of natural records, mainly associated to sedimentary deposits that store detailed information in the form of specific biogenic molecules (i.e. biomarkers). In forested watersheds terrestrial vegetation is an important source of biomarkers like those associated to Lignin, a complex organic polymer used by plants to provide physical support in its tissues. Through litter inputs Lignin is deposited in soils and then is transported to sedimentary environments by rivers (e.g. floodplains, lake bottoms), serving as a source of information about vegetation changes in watersheds. In spite of the critical character of the information extracted from biomarkers in sedimentary records, the very concept of information is still used in a metaphorical sense, even though it was formally defined more than 60 years ago and has been applied extensively in ecology (e.g. Shannon's diversity index). Furthermore, sophisticated techniques are being used to deliver more complex molecular data that require examination and validation as indicators for watershed historical reconstructions. My research aims to explore the applicability of some information metrics (i.e. diversity indices, information coefficients) to a diverse molecular set derived from the chemical depolymerization of lignin deposited in floodplains and lake sediments in different basins. This approach attempts to assess the informational characteristics of Lignin as an indicator of natural/human-induced perturbations in forested watersheds. The formal assessment of the informational characteristics of natural records could have a profound impact not only in our methodological approaches but also in our philosophical view about information and communication in

  3. Realistic modelling of observed seismic motion in compIex sedimentary basins

    Directory of Open Access Journals (Sweden)

    G. F. Panza

    1994-06-01

    Full Text Available Three applications of a numerical technique are illustrated to model realistically the seismic ground motion for complex two-dimensional structures. First we consider a sedimentary basin in the Friuli region, and we model strong motion records from an aftershock of the 1976 earthquake. Then we simulate the ground motion caused in Rome by the 1915, Fucino (Italy earthquake, and we compare our modelling with the damage distribution observed in the town. Finally we deal with the interpretation of ground motion recorded in Mexico City, as a consequence of earthquakes in the Mexican subduction zone. The synthetic signals explain the major characteristics (relative amplitudes, spectral amplification, frequency content of the considered seismograms, and the space distribution of the available macroseismic data. For the sedimentary basin in the Friuli area, parametric studies demonstrate the relevant sensitivity of the computed ground motion to small changes in the subsurface topography of the sedimentary basin, and in the velocity and quality factor of the sediments. The relative Arias Intensity, determined from our numerical simulation in Rome, is in very good agreoment with the distribution of damage observed during the Fucino earthquake. For epicentral distances in the range 50 km-100 km, the source location and not only the local soil conditions control the local effects. For Mexico City, the observed ground motion can be explained as resonance effects and as excitation of local surface waves, and the theoretical and the observed maximum spectral amplifications are very similar. In general, our numerical simulations estimate the maximum and average spectral amplification for specific sites, i.e. they are a very powerful tool for accurate micro-zonation

  4. Alteration of immature sedimentary rocks on Earth and Mars: Recording aqueous and surface-atmosphere processes

    Science.gov (United States)

    Cannon, Kevin M.; Mustard, John F.; Salvatore, Mark R.

    2015-05-01

    Rock alteration and rind formation in analog environments like Antarctica may provide clues to rock alteration and therefore paleoclimates on Mars. Clastic sedimentary rocks derived from basaltic sources have been studied in situ by martian rovers and are likely abundant on the surface of Mars. However, how such rock types undergo alteration when exposed to different environmental conditions is poorly understood compared with alteration of intact basaltic flows. Here we characterize alteration in the chemically immature Carapace Sandstone from Antarctica, a terrestrial analog for martian sedimentary rocks. We employ a variety of measurements similar to those used on previous and current Mars missions. Laboratory techniques included bulk chemistry, powder X-ray diffraction (XRD), hyperspectral imaging and X-ray absorption spectroscopy. Through these methods we find that primary basaltic material in the Carapace Sandstone is pervasively altered to hydrated clay minerals and palagonite as a result of water-rock interaction. A thick orange rind is forming in current Antarctic conditions, superimposing this previous aqueous alteration signature. The rind exhibits a higher reflectance at visible-near infrared wavelengths than the rock interior, with an enhanced ferric absorption edge likely due to an increase in Fe3+ of existing phases or the formation of minor iron (oxy)hydroxides. This alteration sequence in the Carapace Sandstone results from decreased water-rock interaction over time, and weathering in a cold, dry environment, mimicking a similar transition early in martian history. This transition may be recorded in sedimentary rocks on Mars through a similar superimposition mechanism, capturing past climate changes at the hand sample scale. Our results also suggest that basalt-derived sediments could have sourced significant volumes of hydrated minerals on early Mars due to their greater permeability compared with intact igneous rocks.

  5. Geochemical Characteristics of Sedimentary Manganese Deposit of Guichi, Anhui Province, China

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The sedimentary manganese deposits occurring in Gufeng formation of the Permian in Guichi area, south Anhui Province, include manganese carbonate deposit formed by sedimentation, and manganese oxide deposit made by later oxidation. The total REE contents of these samples are relatively low ( < 250 × 10-6), belonging to LREE-enriched type,showing LREE enrichment during the process of formation of Mn deposit, especially during Mn-oxidizing process. Three normalized REE patterns and SCNA-normalized trace elements spider diagrams of the Mn-bearing sequence rocks and ores in this area reflect their same origin of ore sources, which is similar to rock-forming and ore-forming conditions. The Mnforming materials primarily came from the continent with higher mature degree and single material source. The δEu and δCe negative anomaly and Ce anomaly ( < - 0.1 ) manifest that Mn-bearing sequence of the Permian was mostly formed in marine basin and oxidative environment. The Sr and Ba anomaly, Sr/Ba and Co/Ni values reflect the Mn deposit environment was of deep water and high-salinity of marine facies. Although the Ce/La (mean 1.05), Y/Ho (25 ~ 41.5) and trace metals show a variety of correlations with Mn in the ten rock samples, which show multiple sources for the manganese, the analysis of geochemical characteristics indicate that the material sources of Mn deposit have been primarily terrestrially derived. Another source of the manganese probably comes from the seafloor volcanism in this area. Analysis of sedimentary features and geohistoric evolvement reveals that the maximum transgression of the Qixia Period, ore district is then in deep shelf-basin sedimentary setting and the Mn-bearing sequence is deposited.

  6. Alteration of immature sedimentary rocks on Earth and Mars. Recording Aqueous and Surface-atmosphere Processes

    Energy Technology Data Exchange (ETDEWEB)

    Cannon, Kenneth M. [Brown Univ., Providence, RI (United States); Mustard, John F. [Brown Univ., Providence, RI (United States); Salvatore, Mark R. [Arizona State Univ., Mesa, AZ (United States)

    2015-03-05

    The rock alteration and rind formation in analog environments like Antarctica may provide clues to rock alteration and therefore paleoclimates on Mars. Clastic sedimentary rocks derived from basaltic sources have been studied in situ by martian rovers and are likely abundant on the surface of Mars. Moreover, how such rock types undergo alteration when exposed to different environmental conditions is poorly understood compared with alteration of intact basaltic flows. Here we characterize alteration in the chemically immature Carapace Sandstone from Antarctica, a terrestrial analog for martian sedimentary rocks. We employ a variety of measurements similar to those used on previous and current Mars missions. Laboratory techniques included bulk chemistry, powder X-ray diffraction (XRD), hyperspectral imaging and X-ray absorption spectroscopy. Through these methods we find that primary basaltic material in the Carapace Sandstone is pervasively altered to hydrated clay minerals and palagonite as a result of water–rock interaction. A thick orange rind is forming in current Antarctic conditions, superimposing this previous aqueous alteration signature. The rind exhibits a higher reflectance at visible-near infrared wavelengths than the rock interior, with an enhanced ferric absorption edge likely due to an increase in Fe3+ of existing phases or the formation of minor iron (oxy)hydroxides. This alteration sequence in the Carapace Sandstone results from decreased water–rock interaction over time, and weathering in a cold, dry environment, mimicking a similar transition early in martian history. This transition may be recorded in sedimentary rocks on Mars through a similar superimposition mechanism, capturing past climate changes at the hand sample scale. These results also suggest that basalt-derived sediments could have sourced significant volumes of hydrated minerals on early Mars due to their greater permeability compared with intact igneous rocks.

  7. Sedimentary features and exploration targets of Middle Permian reservoirs in the SW Sichuan Basin

    Directory of Open Access Journals (Sweden)

    Guoming Xu

    2015-11-01

    Full Text Available The exploration direction and targets for the large-scale Middle Permian gas reservoirs in the Sichuan Basin are hot spots and challenges in current exploration researches. The exploration successes of large gas field of Cambrian Longwangmiao Formation in Gaoshiti-Moxi region, Central Sichuan Basin, indicated that prospective sedimentary facies belt was the basis for the formation of large gas fields. In this paper, based on seismic data, outcrop data and drilling data, the tectonic framework and sedimentary features of the Middle Permian in the SW Sichuan Basin were comprehensively studied. The following conclusions were reached from the perspective of sedimentary facies control: (1 during the Middle Permian, this region was in shallow water gentle slope belts with high energy, where thick reef flat facies were deposited; (2 the basement was uplifted during Middle Permian, resulting in the unconformity weathering crust at the top of Maokou Formation due to erosion; the SW Sichuan Basin was located in the karst slope belt, where epigenic karstification was intense; and (3 reef flat deposits superimposed by karst weathering crust was favorable for the formation of large-scale reef flat karst reservoirs. Based on the combination of the resources conditions and hydrocarbon accumulation conditions in this region, it was pointed out that the Middle Permian has great potential of large-scale reef flat karst gas reservoir due to its advantageous geological conditions; the Middle Permian traps with good hydrocarbon accumulation conditions were developed in the Longmen Mountain front closed structural belt in the SW Sichuan Basin and Western Sichuan Basin depression slope belt, which are favorable targets for large-scale reef flat karst reservoirs.

  8. Stress field sensitivity analysis in a sedimentary sequence of the Alpine foreland, northern Switzerland

    Science.gov (United States)

    Hergert, T.; Heidbach, O.; Reiter, K.; Giger, S. B.; Marschall, P.

    2015-05-01

    The stress field at depth is a relevant parameter for the design of subsurface constructions and reservoir management. Yet the distortion of the regional stress field due to local-scale features such as sedimentary and tectonic structures or topography is often poorly constrained. We conduct a stress sensitivity analysis using 3-D numerical geomechanical modelling with an elasto-plastic material law to explore the impact of such site-specific features on the stress field in a sedimentary sequence of the Swiss Alpine foreland. The model's dimensions are 14 x 14 x 3 km3 and it contains 10 units with different mechanical properties, intersected by two regional fault zones. An initial stress state is established involving a semi-empirical relationship between the ratio of horizontal to vertical stress and the overconsolidation ratio of argillaceous sediments. The model results indicate that local topography can affect the stress field significantly to depths greater than the relief contrasts at the surface, especially in conjunction with horizontal tectonic loading. The complexity and frictional properties of faults are also relevant. The greatest variability of the stress field arises across the different sedimentary units. Stress magnitudes and stress anisotropy are much larger in stiffer formations such as massive limestones than in softer argillaceous formations. The stiffer formations essentially carry the load of the far-field forces and are therefore more sensitive to changes of the boundary conditions. This general characteristic of stress distribution in the stiff and soft formations is broadly maintained also with progressive loading towards the plastic limit. The stress field in argillaceous sediments within a stack of formations with strongly contrasting mechanical properties like in the Alpine foreland appears to be relatively insensitive to changes in the tectonic boundary conditions and is largely controlled by the maximum stiffness contrast with respect

  9. Recently studied sedimentary records from the eastern Arabian Sea: Implications to Holocene monsoonal variability

    Digital Repository Service at National Institute of Oceanography (India)

    Agnihotri, R.; Kurian, S.

    ://www.earthscienceindia.info/Agnihotri.htm 1 of 14 10/15/2008 9:41 AM Earth Science India Vol.1 (IV), October, 2008, pp. 258-287 http://www.earthscienceindia.info/ Recently studied sedimentary records from the eastern Arabian Sea: Implications to Holocene monsoonal variability Rajesh... biogenic (organic and inorganic) proxies with minimal particle reworking through bioturbation. Agnihotri http://www.earthscienceindia.info/Agnihotri.htm 2 of 14 10/15/2008 9:41 AM Figure 1: Satellite pictures of the Arabian Sea revealing seasonal contrast...

  10. Karst in conglomerates in Catalonia (Spain): morphological forms and sedimentary sequence types recorded on archaeological sites

    OpenAIRE

    Bergadà i Zapata, M. Mercè; Cervelló, Josep M.; Serrat, David, 1949-

    1997-01-01

    This article aims to make the karst morphological forms to be found in conglomerate rocks, as well as the sedimentary sequence types recorded in such deposits, more widely known. Particular attention is paid to points where prehistoric occupation has been traced, sites such as: the Font Major Cave (Espluga de Francoli, Tarragona), the Hort de la Boquera, the Filador Rock-shelter and the Colls Rock-shelter (Margalef de Montsant, Tarragona), and the Parco Cave (Alôs de Balaguer, Lleida). By mea...

  11. Natural Radioactivity Measurements and Radiation Dose Estimation in Some Sedimentary Rock Samples in Turkey

    OpenAIRE

    Akkurt, I.; K. Günoğlu

    2014-01-01

    The natural radioactivity existed since creation of the universe due to the long life time of some radionuclides. This natural radioactivity is caused by γ-radiation originating from the uranium and thorium series and 40K. In this study, the gamma radiation has been measured to determine natural radioactivity of 238U, 232Th, and 40K in collected sedimentary rock samples in different places of Turkey. The measurements have been performed using γ-ray spectrometer containing NaI(Tl) detector and...

  12. An examination of recharge mound decay and fossil gradients in arid regional sedimentary basins

    International Nuclear Information System (INIS)

    In many of the vast arid sedimentary basins of the world, groundwater gradients exist that appear to be anomalous in the context of the probable modern recharge potential. The possibility that such gradients are in fact remnant fossil conditions representing the decay of ancient recharge mounds is examined. An example of decay condition is represented using a resistor-network analogue model in which the time control is based on 14C ages. The decay hypothesis is found to be plausible with realistic aquifer characteristics but a non-homogeneous flow is indicated from the 14C data. (author)

  13. Dispersion behaviour of mobile uranium in sedimentary rock area of aek simamak Sibolga North-Sumatra

    International Nuclear Information System (INIS)

    Dispersion behaviour of mobile uranium in sedimentary rock area of aek simamak sibolga North-Sumatra. The analysis of mobile uranium on 76 stream sediments, 38 water and 40 vegetation samples have been done. The dispersion of mobile uranium on stream sediment and vegetation has reflected the rather significant uranium occurrences. The analysis of Na+, Ca2+, K+, Mg2+, Cl-, SO42-, HCO3-, CO2/3-, pH and Eh in water samples have been done too. A good correlation was found between uranium and Na+ and HCO3- with a correlation coefficient of 0,37. (author). 8 refs.; 8 figs

  14. Depositional Environment of Fine-Grained Sedimentary Rocks of the Sinamar Formation, Muara Bungo, Jambi

    OpenAIRE

    M. Heri Hermiyanto Zajuli; H. Panggabean

    2014-01-01

    DOI: 10.17014/ijog.v8i1.153The research area is situated in the northwestern side of South Sumatra Basin, which is a part of Muara Bungo Regency, Jambi Province. The Oligocene Sinamar Formation consists of shale, claystone, mudstone, sandstone, conglomeratic sandstone, and coal-seam intercalations. This research was focused on fine sedimentary rock of Sinamar Formation, such as shale, claystone, and mudstone. Primary data were collected from SNM boreholes which have depths varying from 75 m u...

  15. Recirculation System for Geothermal Energy Recovery in Sedimentary Formations: Laboratory Experiments and Numerical Simulations

    Science.gov (United States)

    Elkhoury, J. E.; Detwiler, R. L.; Serajian, V.; Bruno, M. S.

    2012-12-01

    Geothermal energy resources are more widespread than previously thought and have the potential for providing a significant amount of sustainable clean energy worldwide. In particular, hot permeable sedimentary formations provide many advantages over traditional geothermal recovery and enhanced geothermal systems in low permeability crystalline formations. These include: (1) eliminating the need for hydraulic fracturing, (2) significant reduction in risk for induced seismicity, (3) reducing the need for surface wastewater disposal, (4) contributing to decreases in greenhouse gases, and (5) potential use for CO2 sequestration. Advances in horizontal drilling, completion, and production technology from the oil and gas industry can now be applied to unlock these geothermal resources. Here, we present experimental results from a laboratory scale circulation system and numerical simulations aimed at quantifying the heat transfer capacity of sedimentary rocks. Our experiments consist of fluid flow through a saturated and pressurized sedimentary disc of 23-cm diameter and 3.8-cm thickness heated along its circumference at a constant temperature. Injection and production ports are 7.6-cm apart in the center of the disc. We used DI de-aired water and mineral oil as working fluids and explored temperatures from 20 to 150 oC and flow rates from 2 to 30 ml/min. We performed experiments on sandstone samples (Castlegate and Kirby) with different porosity, permeability and thermal conductivity to evaluate the effect of hydraulic and thermal properties on the heat transfer capacity of sediments. The producing fluid temperature followed an exponential form with time scale transients between 15 and 45 min. Steady state outflow temperatures varied between 60% and 95% of the set boundary temperature, higher percentages were observed for lower temperatures and flow rates. We used the flow and heat transport simulator TOUGH2 to develop a numerical model of our laboratory setting. Given

  16. Geology of East Egypt greenstone field in Neoproterozoic isoand arc: Reconstruction of Iron formation sedimentary environment.

    Science.gov (United States)

    Kiyokawa, S.; Suzuki, T.

    2015-12-01

    Geology of East Egypt greenstone-granit belt which is northern part of Nubia shield was identified neoproterozoic island arc amalgamated sections. There are several iron formation within these greenstone belt. Age data shows this iron formation may be overlaped during 700 Ma Snowball period, how ever, there is no detail report of well preserved ice related evidences. We now started detail field work for identified tectonic reconstruction, original stratigraphy around Iron formation and sedimentary environment during the iron formation sedimentation area. East Egyptian shield was divided three geology, Proterozoic greenstone complex, 700-600 Granitic domes and cover sequence (Hammamet Group). We focus three area to identified sedimentary environment of iron sedimentation. Along the north-south trend of Wadi EL Dabban area are, we named Wadi branch as West site is RW-0 ~ 12, East site is RE-0 ~ 12 from north to south. Northern area is structurally moderate, southern portion is north dipping. Southern portion was intruded by granite and several place contain granitic dikes. Northeast to eastern area are identified younger sedimentary sequence (Hammamat Group) which is unconformablly overlay on the other iron formation bearing greenstone belt. Structurally these area is divided four units. Wadi was divided by right-lateral strike-ship fault. The displacement are more than 3 km. Also north dipping faults are identified.East-West trend fault are divided two units. It is divided NE, SE, NW and NS units.SW unit is most well preserved thick sequence of the Iron formation. SW unit is well preserved iron formation sequence within thick volcaniclastics. This unit mostly north dipping around 40-60 degree. Structural repetition in not well understand. Reconstract stratigraphy in this unit is at least 4000m in thickness. 5 member is identified in this sequence. Several thin iron formations are observed with in pillow lava and volcaniclastic sequence. These very thick

  17. Sedimentary facies and paleoenvironmental interpretation of a Holocene marsh in the Gironde Estuary in France

    Institute of Scientific and Technical Information of China (English)

    WANG Jianhua; MASSE Laurent; TASTET Jean-Pierre

    2006-01-01

    The Monards Marsh is located on the northeastern bank of the Gironde Estuary in France. Lithological, sedimentological and micropalaeontological investigations were made on four cores to determine the evolution of Holocene sedimentary environments and processes in this area over the last 6 000 a. Three main lithological facies are distinguished from bottom to top: (1) grey laminated silty-sandy clay; (2) homogeneous dark grey silty clay; and (3) compact silty clay. About 26 benthic foraminifera species are identified and divided into six groups according to their ecological characteristics. In association with lithology, sedimentary structures and grainulometry, the distribution of foraminifera group is used to define external slikke, internal slikke, external schorre, internal schorre, and continental marsh facies. Combined with 14C(AMS) dating, these data indicate four successive paleoenvironments in the Monards Marsh: (1) Holocene transgression resulted in the development of a basal schorre facies overlying fluvial deposits that transformed to slikke facies sedimentation; the transgression maximum occurred around 5 600 to 5 400 a BP and was inferred to be associated with the last phase of the rapid Holocene sea-level rise; (2) post-trangressive maximum sedimentation resulted in a regressive sequence of deposits prograding towards the estuary, corresponding to the stabilisation of sea level after 5 400 a BP; (3) a slight positive tendency in the sea level around 2 800 a BP recorded in the central part of the marsh; and (4) the wetland to a continental marsh environment. The sequential pattern for the evolution of wetlands in this estuarine area during the Holocene is fluvial facies-blackish schorre facies-slikke facies-blackish schorre facies-continental marsh facies. Characteristics of sedimentary facies distribution and evolution reveal that the development of Holocene salt marsh in this area was controlled by the sea-level change and tidal range. The

  18. Sedimentary ladderane core lipids as potential indicators of hypoxia in the East China Sea

    Institute of Scientific and Technical Information of China (English)

    ZHAO Zongshan; CAO Yali; LI Li; SONG Guodong; YANG Hongmei; LIU Sumei; ZHAO Meixun

    2013-01-01

    Anammox (anaerobic ammonium oxidation) is an important process in many suboxic to anoxic marine environments for converting fixed nitrogen to N2,and has a major impact on the marine nitrogen cycle.Ladderane core lipids have been utilized as an indicator of the contribution of anammox to the marine nitrogen cycles.However,such studies have not been reported for the China seas and little is known about the importance ofanammox within the nitrogen cycle of these marginal seas.In the research reported here,the ladderane core lipid contents of 17 surface sediment samples from the East China Sea are reported,and their spatial distribution is investigated.C1s-[5]-ladderane FAME,C20-[5]-ladderane FAME and C20-[3]-ladderane FAME have all been detected,suggesting that the anammox bacteria are widely present within the study area.The total contents of the three ladderane lipids (ΣFAMEs) range from 24-355 ng/g (weight of dry sediments),with higher contents occurring in the Minzhe Mud Zone and broadly coincident with the spatial distribution of hypoxia.It is suggested that the sedimentary ladderane core lipids are mainly produced in the water column and their sedimentary contents can be used as indicators of water colunm hypoxia.

  19. Rayleigh-wave ellipticity and shallow structure in sedimentary basins: the Po Plain (northern Italy)

    Science.gov (United States)

    Berbellini, A.; Morelli, A.; Ferreira, A. M. G.

    2015-12-01

    The amplitude ratio between horizontal and vertical components of Rayleigh waves (also known as ellipticity) is in principle uniquely sensitive to local earth structure beneath each recording station. Rayleigh wave ellipticity is mostly influenced by the shallowest layers, so it can be effectively used to infer the structure of the uppermost crust, with particular relevance for sedimentary environments. We implement an automatic method to measure Rayleigh wave ellipticity, and extensively apply it to teleseismic records from the northern part of Italy, for a period range between 10s and 130s. As expected, no appreciable correlation with epicenter distance or azimuth can be seen, but rather a strong correlation with local structure: generally high horizontal to vertical amplitude ratios are seen in sedimentary settings, with respect to Alpine and Apenninic crystalline-rock terrains. We verify that shortest usable period may be limited by very low shear-wave velocity in shallow sediments, when the assumed retrograde elliptical particle motion polarisation for the fundamental mode breaks off. The highly non-linear sensitivity of frequency-dependent ellipticity curves can then be inverted using a direct search method to infer shear wave velocity profiles below stations. By comparing our results with local a priori geological information we show that robust information can indeed be retrieved.

  20. A non-tectonic origin for the present day stress field in the sedimentary Paris Basin

    Science.gov (United States)

    Cornet, Francois; Magnenet, Vincent

    2016-04-01

    The large scale stress patterns observed in intraplate area is generally considered to result from far-field boundary forces that drive plate tectonics. However, no present day deformation has been detected in the Paris Basin, yet significant deviatoric stresses are measured in limestone formations observed above soft argillite layers encountered in this region at depths close to 500m. Further, the pore pressure measured in the argillite is larger than that measured in the surrounding permeable zones. These observations suggest a presently active source of stress in this sedimentary system. We propose that this stress is not related to tectonics but to pressure solution effects activated by pore pressure transients. These transients develop in the natural fracture system that affects the limestone formations. They are linked to climatic variations and involve periods that range from thousands to hundreds of thousands years. This mechanism generates time-dependent shear stresses in soft formations and explains overpressures observed in the very low permeability argillite. This mechanism may be modeled by different visco-elastic behaviors for the various formations. It outlines the influence of time dependent material properties on the present day stress field. These results imply that the viscoelastic properties of sedimentary formations raise a strong difficulty for extrapolating measured surface deformations to basement rocks in domains of very slow tectonics.

  1. Thermal conductivity of sedimentary rocks - selected methodological, mineralogical and textural studies

    Energy Technology Data Exchange (ETDEWEB)

    Midttoemme, Kirsti

    1997-12-31

    The thermal conductivity of sedimentary rocks is an important parameter in basin modelling as the main parameter controlling the temperature within a sedimentary basin. This thesis presents measured thermal conductivities, mainly on clay- and mudstone. The measured values are compared with values obtained by using thermal conductivity models. Some new thermal conductivity models are developed based on the measured values. The values obtained are less than most previously published values. In a study of unconsolidated sediments a constant deviation was found between thermal conductivities measured with a needle probe and a divided bas apparatus. Accepted thermal conductivity models based on the geometric mean model fail to predict the thermal conductivity of clay- and mudstone. Despite this, models based on the geometric mean model, where the effect of porosity is taken account of by the geometric mean equation, seem to be the best. Existing models underestimate the textural influence on the thermal conductivity of clay- and mudstone. The grain size was found to influence the thermal conductivity of artificial quartz samples. The clay mineral content seems to be a point of uncertainty in both measuring and modelling thermal conductivity. A good universal thermal conductivity model must include many mineralogical and textural factors. Since this is difficult, different models restricted to specific sediment types and textures are suggested to be the best solution to obtain realistic estimates applicable in basin modelling. 243 refs., 64 figs., 31 tabs.

  2. Shell Bed Identification of Kaliwangu Formation and its Sedimentary Cycle Significance, Sumedang, West Java

    Directory of Open Access Journals (Sweden)

    Aswan Aswan

    2014-07-01

    Full Text Available DOI: 10.17014/ijog.v8i1.151Kaliwangu Formation cropping out around Sumedang area contains mollusk fossils dominated by gastropods and bivalves. In terms of sequence stratigraphy, each sedimentary cycle generally consists of four shell bed types: Early Transgressive Systems Tract (Early TST deposited above an erosional surface or sequence boundary, that is characterized by shell disarticulation, trace fossils, gravelly content, no fossil orientation direction, and concretion at the bottom; Late Transgressive Systems Tract (Late TST identified by articulated (conjoined specimen in its life position, that shows a low level abration and fragmentation, adult specimen with complete shells, and variation of taxa; Early Highstand Systems Tract (Early HST characterized by adult taxa that was found locally in their life position with individual articulation, juvenile specimens frequently occured; Late Highstand Systems Tract (Late HST determined as multiple-event concentrations, disarticulated shell domination, and some carbon or amber intercalation indicating terrestrial influence. Shell bed identification done on this rock unit identified nineteen sedimentary cycles.

  3. Nutrient regeneration susceptibility under contrasting sedimentary conditions from the Rio de Janeiro coast, Brazil.

    Science.gov (United States)

    Matos, Christiene R L; Mendoza, Ursula; Diaz, Rut; Moreira, Manuel; Belem, Andre L; Metzger, Edouard; Albuquerque, Ana Luiza S; Machado, Wilson

    2016-07-15

    Dissolved silicate (DSi), NH4(+), NO3(-) and PO4(3-) susceptibility to be exchanged between sediment pore waters and overlying waters was evaluated in Jurujuba Sound (JS station) and Coroa Grande Sound (CGS station), southeastern Brazil. Sedimentary elemental (C, N and P) and isotopic (δ(13)C and δ(15)N) compositions evidenced stronger anthropogenic fertilization in JS station. Net NO3(-) influxes from overlying waters occurred, which was two orders of magnitude higher under the more fertilized condition. This condition resulted in 6-13-times higher net effluxes of NH4(+), DSi and PO4(3-) to overlying waters. Vertical alternation between production and consumption processes in pore waters contributed for a more limited regeneration in CGS station. This was associated with diagenetic responses to sedimentary grain size variability in deeper layers and biological disturbance in upper layers. Nearly continuous production of NH4(+), DSi and PO4(3-) in pore waters implied in intensified susceptibility to remobilization under the eutrophic condition of JS station. PMID:27156036

  4. A 60-year sedimentary record of natural and anthropogenic impacts on Lake Chenghai, China.

    Science.gov (United States)

    Zan, Fengyu; Huo, Shouliang; Xi, Beidou; Zhang, Jingtian; Liao, Haiqing; Wang, Yue; Yeager, Kevin M

    2012-01-01

    Recent sediments from Lake Chenghai, China, were investigated at high temporal resolution to trace both natural and anthropogenic effects on the lake using total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), organic phosphorus (Po), inorganic phosphorus (Pi) and organic carbon and nitrogen stable isotopes (delta13Corg and delta15N) in a 137Cs-dated sediment core. The results indicated that the sedimentary record covers the last 60 years, during which the lake had undergone apparent changes in nutrient sources and productivity in response to nutrient loading. Prior to the late 1980s, the nutrient contents in sediments mainly originated from algae and lake productivity was relatively stable. Since the late 1980s, increasing TOC, TN and TP concentrations together with the change of delta13Corg and delta15N suggested anthropogenic perturbations in nutrient loading and lake productivity. Endogenic nutrients derived from algae and anthropogenic inputs were two important sources of sedimentary nutrients. The anthropogenic nutrients mainly originated from the discharge of industrial wastewater and artificial cultivation of Spirulina after the middle 1980s, and domestic wastewater discharged from Yongsheng County since 1993. PMID:22894093

  5. Impacts of agricultural expansion on sedimentary organic matter composition in Lake Soyang (South Korea)

    Science.gov (United States)

    Kang, Sujin; Kim, Jung-Hyun; Sinninghe Damsté, Jaap S.; Gal, Jong-Ku; Lee, Dong-Hun; Lee, Sang-Han; Kim, Bomchul; Shin, Kyung-Hoon

    2016-04-01

    The agricultural area has been expanded since the 19th century and agricultural activities such as eroded soils, nutrient, and organic matters may impact aquatic environments. The Lake Soyang is the deepest and largest artificial dam reservoir constructed in South Korea in 1973. Lake Soyang has been experienced an expansion of agricultural area since the 1990s. In this study, we investigated the impact of agricultural expansion on sedimentary organic matter in Lake Soyang. We collected soils (n=7), lake surface sediments (n=9) and a 50-cm sediment core at near the dam for the analysis of total organic carbon (TOC) and total nitrogen (TN) contents, stable isotopic composition of TOC and TN (δ13CTOC and δ15N), and glycerol dialkyl glycerol tetraethers (GDGTs). The age model of the sediment core is based on 210Pb analysis. In lake surface sediments, bulk and GDGT-derived geochemical data indicate that C3-derived soil OM was the major source in the upper part of the lake while an aquatic contribution increased in the lower part of the lake. The sediment core showed a distinctive shift in all parameters considered at 15 cm core depth. However, it was difficult to constrain the exact age of this depth due to the dating uncertainties. Nonetheless, our study implies the potential influence of agricultural expansion on changes in sedimentary OM composition in Lake Soyang.

  6. Hydrological and sedimentary controls over fluvial thermal erosion, the Lena River, central Yakutia

    Science.gov (United States)

    Tananaev, Nikita I.

    2016-01-01

    Water regime and sedimentary features of the middle Lena River reach near Yakutsk, central Yakutia, were studied to assess their control over fluvial thermal erosion. The Lena River floodplain in the studied reach has complex structure and embodies multiple levels varying in height and origin. Two key sites, corresponding to high and medium floodplain levels, were surveyed in 2008 to describe major sedimentary units and properties of bank material. Three units are present in both profiles, corresponding to topsoil, overbank (cohesive), and channel fill (noncohesive) deposits. Thermoerosional activity is mostly confined to a basal layer of frozen channel fill deposits and in general occurs within a certain water level interval. Magnitude-frequency analysis of water level data from Tabaga gauging station shows that a single interval can be deemed responsible for the initiation of thermal action and development of thermoerosional notches. This interval corresponds to the discharges between 21,000 and 31,000 m3 s- 1, observed normally during spring meltwater peak and summer floods. Competence of fluvial thermal erosion depends on the height of floodplain level being eroded, as it acts preferentially in high floodplain banks. In medium floodplain banks, thermal erosion during spring flood is constrained by insufficient bank height, and erosion is essentially mechanical during summer flood season. Bank retreat rate is argued to be positively linked with bank height under periglacial conditions.

  7. Nitrogen isotope dynamics and fractionation during sedimentary denitrification in Boknis Eck, Baltic Sea

    Directory of Open Access Journals (Sweden)

    K. Dähnke

    2013-05-01

    Full Text Available The global marine nitrogen cycle is constrained by nitrogen fixation as a source of reactive nitrogen, and denitrification or anammox on the sink side. These processes with their respective isotope effects set the marine nitrate 15N-isotope value (δ15N to a relatively constant average of 5‰. This value can be used to better assess the magnitude of these sources and sink terms, but the underlying assumption is that sedimentary denitrification and anammox, processes responsible for approximately one-third of global nitrogen removal, have little to no isotope effect on nitrate in the water column. We investigated the isotope fractionation in sediment incubations, measuring net denitrification and nitrogen and oxygen stable isotope fractionation in surface sediments from the coastal Baltic Sea (Boknis Eck, northern Germany, a site with seasonal hypoxia and dynamic nitrogen turnover. Sediment denitrification was fast, and regardless of current paradigms assuming little fractionation during sediment denitrification, we measured fractionation factors of 18.9‰ for nitrogen and 15.8‰ for oxygen in nitrate. While the input of nitrate to the water column remains speculative, these results challenge the current view of fractionation during sedimentary denitrification and imply that nitrogen budget calculations may need to consider this variability, as both preferential uptake of light nitrate and release of the remaining heavy fraction can significantly alter water column nitrate isotope values at the sediment–water interface.

  8. Nitrogen isotope dynamics and fractionation during sedimentary denitrification in Boknis Eck, Baltic Sea

    Directory of Open Access Journals (Sweden)

    K. Dähnke

    2013-01-01

    Full Text Available The global marine nitrogen cycle is constrained by nitrogen fixation as a source of reactive nitrogen, and denitrification or anammox on the sink side. These processes with their respective isotope effects set the marine nitrate 15N-isotope value (δ15N to a relatively constant average of 5‰. This value can be used to better assess the magnitude of these sources and sink terms, but the underlying assumption is that sedimentary denitrification and anammox, processes responsible for approximately one third of global nitrogen removal, have little to no isotope effect on nitrate in the water column.

    We investigated the isotope fractionation in sediment incubations, measuring net denitrification and nitrogen and oxygen stable isotope fractionation in surface sediments from the coastal Baltic Sea (Boknis Eck, Northern Germany, a site with seasonal hypoxia and dynamic nitrogen turnover.

    We found tremendously high denitrification rates, and regardless of current paradigms assuming little fractionation during sediment denitrification, we measured fractionation factors of 18.9‰ for nitrogen and 15.8‰ for oxygen in nitrate. While the input of nitrate to the water column remains speculative, these results challenge the current view of fractionation during sedimentary denitrification and imply that nitrogen budget calculations may need to consider this variability, as both preferential uptake of light nitrate and release of the remaining heavy fraction can significantly alter water column nitrate isotope vales at the sediment-water interface.

  9. Sedimentary facies of Maastrichtian to Danian deposits in Amur River area, Russian Far East

    Institute of Scientific and Technical Information of China (English)

    Shigeyuki Suzuki; Abdul R. Ashraf; Hakuyu Okada

    2004-01-01

    Sedimentary facies of the Tsagayan Formation is distributed in the eastern Zeya-Bureya Basin has been analyzed. The formation is of the Maastrichtian to Danian in age and characterized by the cyclicity of the fining-upwards successions. Analysis of environmental changes during the K/T boundary is the focus of this study. Five facies have been identified: Facies A, thick and laterally extensive coarse-grained to medium-grained sandstone units, interpreted as channelfill deposits; Facies B, parallel-laminated to massive mudstone units interpreted as interchannel lakes and flood plain deposits; Facies C, sheet-like medium-grained to fine-grained sandstones interpreted as crevasse splay deposits;Facies D, coal to coaly mudstone beds interpreted as deposits ofpeatlands; Facies E, very poorly sorted sandy mudstone beds interpreted as debris flow deposits. Fluvial environments with the low-relief flat topography was inferred. A channel transported large volumes of clasts, and a flood basin with interchannel lakes and peatlands was deciphered. Any distinct change of sedimentary environments has not been identified throughout the Tsagayan Formation (including the K/T boundary). However, two beds of debris flow deposits were identified. The one occurs at the uppermost part of the lower Tsagayan Subformation and contains dinosaur fossils. The other is intercalated in the upper Tsagayan Subformation.

  10. Characteristics of sedimentary polycyclic aromatic hydrocarbons (PAHs) in the subtropical Feitsui Reservoir, Taiwan

    Science.gov (United States)

    Fan, Cheng-Wei; Yang, Tien-Nan; Kao, Shuh-Ji

    2010-09-01

    SummaryPolycyclic aromatic hydrocarbons (PAHs) are usually loaded through atmospheric deposition into a water body and eventually into sediments. We study the PAHs from a 22-cm sediment core collected from the subtropical Feitsui Reservoir in Taiwan, and find the PAHs deposition characteristics in the reservoir, the man-made water body, is different from those in natural water bodies. The surficial sedimentary PAH fluxes are significantly higher than those in the European high altitude mountain lakes and those in the northeastern USA urban/industrial lakes. However, the catchment-corrected PAH fluxes normalized by the ratios of the catchment area to the water surface area are comparable to those of remote lakes in Europe and USA, suggesting the sedimentary PAHs in the reservoir is fluvial dominated, i.e., the reservoir system concentrated the atmospheric PAHs from the catchment area into the sediments. PAHs distribution found in the Feitsui Reservoir indicates both biogenic and anthropogenic origins. We also find the vehicular transport upstream of the reservoir is likely one of the PAHs sources to this reservoir.

  11. Sedimentary structures of tidal flats: A journey from coast to inner estuarine region of eastern India

    Indian Academy of Sciences (India)

    A Chakrabarti

    2005-06-01

    Sedimentary structures of some coastal tropical tidal flats of the east coast of India, and inner estuarine tidal point bars located at 30 to 50 kilometers inland from the coast, have been extensively studied under varying seasonal conditions. The results reveal that physical features such as flaser bedding, herringbone cross-bedding, lenticular bedding, and mud/silt couplets are common to both the environments. In fact, flaser bedding and lenticular bedding are more common in the point bar facies during the monsoon months than in the coastal tidal flat environments. Interference ripples, though common in both the environments, show different architectural patterns for different environmental domains. Interference ripples with thread-like secondary set overriding the earlier ripple-form, resembling wrinkle marks, are the typical features in estuarine point bars near the high water region. Because structures which are so far considered as key structures for near-coastal tidal flats are common to both the environments, caution should be exercised for deciphering palaeo-environments, particularly for Proterozoic rocks, where one has to depend only on physical sedimentary structures.

  12. Prediction of CO2 leakage during sequestration into marine sedimentary strata

    International Nuclear Information System (INIS)

    Deep ocean storage of CO2 could help reduce the atmospheric level of greenhouse gas as part of a climate change mitigation strategy. In this paper, a multiphase flow model of CO2 sequestration into deep ocean sediments was designed associated with the formation of CO2 hydrates. A simplified assumption was proposed to predict the critical time of CO2 leakage from marine sedimentary strata into seawater. Moreover, some principal parameters, which include the permeability, anisotropy, total injection amount, and length of the injection part of wellbores, were investigated by numerical simulations. The numerical estimates are used to assess the feasibility and effectiveness of CO2 storage in deep ocean sediments. Accurately predicting the actual fate of liquid CO2 sequestered into the marine sedimentary strata at depths greater than 500 m is complicated by uncertainties associated with not only the chemical-physical behavior of CO2 under such conditions but also the geo-environment of disposal sites. Modeling results have shown some implications that the effectiveness of CO2 ocean sequestration depends mainly on the injection conditions (such as injection rate, total injection amount, and the depth of injection), the site geology (such as permeability and anisotropy of disposal formations), and the chemical-physical behavior of CO2 in marine environment

  13. Genetic data from algae sedimentary DNA reflect the influence of environment over geography

    Science.gov (United States)

    Stoof-Leichsenring, Kathleen R.; Herzschuh, Ulrike; Pestryakova, Luidmila A.; Klemm, Juliane; Epp, Laura S.; Tiedemann, Ralph

    2015-08-01

    Genetic investigations on eukaryotic plankton confirmed the existence of modern biogeographic patterns, but analyses of palaeoecological data exploring the temporal variability of these patterns have rarely been presented. Ancient sedimentary DNA proved suitable for investigations of past assemblage turnover in the course of environmental change, but genetic relatedness of the identified lineages has not yet been undertaken. Here, we investigate the relatedness of diatom lineages in Siberian lakes along environmental gradients (i.e. across treeline transects), over geographic distance and through time (i.e. the last 7000 years) using modern and ancient sedimentary DNA. Our results indicate that closely-related Staurosira lineages occur in similar environments and less-related lineages in dissimilar environments, in our case different vegetation and co-varying climatic and limnic variables across treeline transects. Thus our study reveals that environmental conditions rather than geographic distance is reflected by diatom-relatedness patterns in space and time. We tentatively speculate that the detected relatedness pattern in Staurosira across the treeline could be a result of adaptation to diverse environmental conditions across the arctic boreal treeline, however, a geographically-driven divergence and subsequent repopulation of ecologically different habitats might also be a potential explanation for the observed pattern.

  14. A 60-year sedimentary record of natural and anthropogenic impacts on Lake Chenghai, China

    Institute of Scientific and Technical Information of China (English)

    Fengyu Zan; Shouliang Huo; Beidou Xi; Jingtian Zhang; Haiqing Liao; Yue Wang; Kevin M.Yeager

    2012-01-01

    Recent sediments from Lake Chenghai,China,were investigated at high temporal resolution to trace both natural and anthropogenic effects on the lake using total organic carbon (TOC),total nitrogen (TN),total phosphorus (TP),organic phosphorus (Po),inorganic phosphorus (Pi) and organic carbon and nitrogen stable isotopes (δ13Corg and δ15N) in a 137Cs-dated sediment core.The results indicated that the sedimentary record covers the last 60 years,during which the lake had undergone apparent changes in nutrient sources and productivity in response to nutrient loading.Prior to the late 1980s,the nutrient contents in sediments mainly originated from algae and lake productivity was relatively stable.Since the late 1980s,increasing TOC,TN and TP concentrations together with the change of δ13Corg and δ15N suggested anthropogenic perturbations in nutrient loading and lake productivity.Endogenic nutrients derived from algae and anthropogenic inputs were two important sources of sedimentary nutrients.The anthropogenic nutrients mainly originated from the discharge of industrial wastewater and artificial cultivation of Spirulina after the middle 1980s,and domestic wastewater discharged from Yongsheng County since 1993.

  15. Perturbation induced changes in substrate use by the blue mussel, Mytilus edulis, in sedimentary systems

    Science.gov (United States)

    wa Kangeri, Arno K.; Jansen, Jeroen M.; Barkman, Barbara R.; Donker, Jasper J. A.; Joppe, Daniel J.; Dankers, Norbert M. J. A.

    2014-01-01

    For sessile benthic marine organisms adhesion to a stable substrate is important for survival. Sedimentary systems, however, generally lack stable surfaces. How sessile species like the mussel, Mytilus edulis, are able to achieve stability in unstable sediments is not fully understood. An intertidal mussel bed in the tidal flats in the Western portion of the Dutch Wadden Sea was selected to investigate adhesion behavior of M. edulis. Sampling was conducted along a hydrodynamic gradient along the Front-edge, Center and Back-edge of a mussel bed. Mussels along the bed edges were characterized by adhesion to fine shell debris and high numbers of byssus threads. Mussels in the center of the bed were characterized by adhesion to shells of living conspecifics and relatively low numbers of byssus threads. An experimental investigation to isolate the role of perturbation on adhesion strategies was carried out under laboratory conditions. Experimental results show that under perturbed conditions mussels developed increased numbers of byssus threads relative to mussels left unperturbed. Additionally, mussels subjected to perturbation preferentially adhered more frequently to fine shell debris while unperturbed mussels adhered more frequently to conspecifics. Results show that differentiation in adhesion strategy is driven by physical perturbation and mediated by bed density. The results also suggest that adhesion by mussels in a sedimentary environment is a selective process in which larger shell fragments and shells of conspecifics are the preferred substrate.

  16. The Behaviour of Fracture Growth in Sedimentary Rocks: A Numerical Study Based on Hydraulic Fracturing Processes

    Directory of Open Access Journals (Sweden)

    Lianchong Li

    2016-03-01

    Full Text Available To capture the hydraulic fractures in heterogeneous and layered rocks, a numerical code that can consider the coupled effects of fluid flow, damage, and stress field in rocks is presented. Based on the characteristics of a typical thin and inter-bedded sedimentary reservoir, China, a series of simulations on the hydraulic fracturing are performed. In the simulations, three points, i.e., (1 confining stresses, representing the effect of in situ stresses, (2 strength of the interfaces, and (3 material properties of the layers on either side of the interface, are crucial in fracturing across interfaces between two adjacent rock layers. Numerical results show that the hydrofracture propagation within a layered sequence of sedimentary rocks is controlled by changing in situ stresses, interface properties, and lithologies. The path of the hydraulic fracture is characterized by numerous deflections, branchings, and terminations. Four types of potential interaction, i.e., penetration, arrest, T-shaped branching, and offset, between a hydrofracture and an interface within the layered rocks are formed. Discontinuous composite fracture segments resulting from out-of-plane growth of fractures provide a less permeable path for fluids, gas, and oil than a continuous planar composite fracture, which are one of the sources of the high treating pressures and reduced fracture volume.

  17. Heterogeneous arsenic enrichment in meta-sedimentary rocks in central Maine, United States.

    Science.gov (United States)

    O'Shea, Beth; Stransky, Megan; Leitheiser, Sara; Brock, Patrick; Marvinney, Robert G; Zheng, Yan

    2015-02-01

    Arsenic is enriched up to 28 times the average crustal abundance of 4.8 mg kg(-1) for meta-sedimentary rocks of two adjacent formations in central Maine, USA where groundwater in the bedrock aquifer frequently contains elevated As levels. The Waterville Formation contains higher arsenic concentrations (mean As 32.9 mg kg(-1), median 12.1 mg kg(-1), n=38) than the neighboring Vassalboro Group (mean As 19.1 mg kg(-1), median 6.0 mg kg(-1), n=38). The Waterville Formation is a pelitic meta-sedimentary unit with abundant pyrite either visible or observed by scanning electron microprobe. Concentrations of As and S are strongly correlated (r=0.88, ppyrrhotite (mean As 1 mg kg(-1), n=15) during de-sulfidation reactions: the resulting metamorphic rocks contain arsenic but little or no sulfur indicating that the arsenic is now in new mineral hosts. Secondary weathering products such as iron oxides may host As, yet the geochemical methods employed (oxidative and reductive leaching) do not conclusively indicate that arsenic is associated only with these. Instead, silicate minerals such as biotite and garnet are present in metamorphic zones where arsenic is enriched (up to 130.8 mg kg(-1) As) where S is 0%. Redistribution of already variable As in the protolith during metamorphism and contemporary water-rock interaction in the aquifers, all combine to contribute to a spatially heterogeneous groundwater arsenic distribution in bedrock aquifers. PMID:24861530

  18. Earthquake sources in the sedimentary thick of Azerbaijan and Caspian sea region

    International Nuclear Information System (INIS)

    Full text : With the aim to determine the character of earthquakes' sources distribution by the depth and to reveal on this base the peculiarities of seismogenesis and conditions of sources formation within studied region the critical analysis of earthquakes' sources depths of Azerbaijan and Caspian sea region had been carried out in the present paper. Earthquakes' sources spatial distribution by the depth showing in the region their coincidence mainly with depth intervals 0-10 and 15-20 km, this fact allows to assert their connection with sedimentary thick. Thus, this reason gives a reason to suppose it as main structural element within considered area responsible for seismogenesis. Sedimentary thick can be considered as general source of acting stresses from the point of view of mud volcanism and seismicity paragenesis. Comparative description of seismicity temporal distribution within different structural zones of Caspian sea region showed the important role of mud volcanism in seismogenesis that controls the maximum level of seismicity. The peculiarities of earthquakes caused in result of mud volcanoes' eruptions are evidence of reduction reality of seismic hazard through stimulation of different groups mud volcanoes activity.

  19. Developing high-resolution carbon-13 and silicon-29 MRI of solids in sedimentary rocks

    Science.gov (United States)

    Blum, Robert; Barrett, Sean; Viswanathan, Ravinath; Song, Yi-Qiao

    2014-03-01

    Mapping pore structure and flow properties of sedimentary rock is directly relevant to current challenges in geophysics like carbon sequestration and oil/gas exploration. Such applications require detailed information about both structure and composition of porous rocks. However, existing scanning methods tend to be limited to gathering one or the other type of information. MRI could be used to measure both composition and structure simultaneously, but conventional MRI in such systems, which targets the proton signal of interstitial fluid, is severely limited by signal losses due to magnetic susceptibility inhomogeneity. Our lab has recently made advances in obtaining high spatial resolution (sub-400 μm)3 three-dimensional 31P MRI of bone through use of the quadratic echo line-narrowing sequence (1). In this talk, we describe our current work applying these methods to sedimentary rock, targeting the isotopes 13C and 29Si. We describe the results of characterization of limestone and shale samples, and we discuss our progress with producing MRI of these systems. (1) M. Frey, et al. PNAS 109: 5190 (2012)

  20. Searching for tsunamis evidences on the Algarve (Southern Portugal) continental shelf sedimentary record

    Science.gov (United States)

    Drago, Teresa; Silva, Pedro; Lopes, Ana; Magalhães, Vitor; Roque, Cristina; Rodrigues, Ana Isabel; Noiva, João; Terrinha, Pedro; Mena, Anxo; Francés, Guillermo; Kopf, Achim; Völker, David; Omira, Rachid; Baptista, Maria Ana

    2016-04-01

    Tsunami hazard assessment is important in order to prevent and/or minimize its effects, which is only possible if a complete and long record dataset of past events is available, allowing the estimation of their recurrence intervals. The knowledge of past tsunami events are based on instrumental, historical and geological records. Although instrumental and historical records are reliable sources they are limited in time. Geological records can give a much more extended reconstruction overview of thousand years, which can provide a good estimation of tsunami return periods. Most of the existing studies have been conducted onshore and only a few were based on offshore sedimentary record. These last ones, have the advantage to provide a more continuous and almost undisturbed records but the identification of tsunami sediments in marine environment require a multi-proxy approach in order to better identify the allochtonous layers/deposits and to differentiate them from storm deposits. In the context of ASTARTE project (FP7), five gravity and piston cores on the southern Portuguese continental shelf collected in 2008 and 2014 were studied. The methodology included XRF, MSCL, sedimentological and magnetic analyses. Preliminary results show some identifiable layers that may related with allochthonous sedimentary material, compatible with a genesis resulting from tsunami backwash sediment transport and deposition. Acknowledgments - Publication supported by project FCT UID/GEO/50019/2013 - Instituto Dom Luiz.

  1. A sugar biomarker proxy for assessing terrestrial versus aquatic sedimentary input

    Science.gov (United States)

    Hepp, Johannes; Rabus, Max; Laforsch, Christian; Anhäuser, Tobias; Glaser, Bruno; Zech, Michael

    2016-04-01

    Lake sediments are valuable, often continuous and potentially high resolution archives for studying past climate changes. Thereby, one of the crucial questions is often whether the origin of the organic matter in lake sediments is allochthonous (terrestrial) or autochthonous (aquatic). Here we present patterns of neutral sugars of various plants and algae species to answer the question whether the deoxyhexoses (fucose, rhamnose) to pentoses (arabinose, xylose) ratio can serve as a proxy for aquatic versus terrestrial sedimentary lake input, respectively. Our sugar pattern results show that the fucose + rhamnose content plotted against arabinose and xylose in a ternary diagram can be used to distinguish between algae and other (namely aquatic plants, emergent plant, and terrestrial plants) sugar sources. This finding is confirmed by a compilation with sugar data from the literature. Mosses plot within the range of algae. Although the (fucose + rhamnose)/(arabinose + xylose) ratio yields some overlapping between algae and soil/litter samples, we recommend this ratio, particularly when applied within a multiproxy approach, as promising proxy for distinguishing between aquatic vs. terrestrial organic matter in sedimentary archives. Regarding the sugar concentrations of the investigated samples, emergent plants show the highest values as well as the highest variability. Mosses, aquatic plants and algae yield lower sugar concentrations comparable to those of terrestrial plants.

  2. Natural Radioactivity Measurements and Radiation Dose Estimation in Some Sedimentary Rock Samples in Turkey

    Directory of Open Access Journals (Sweden)

    I. Akkurt

    2014-01-01

    Full Text Available The natural radioactivity existed since creation of the universe due to the long life time of some radionuclides. This natural radioactivity is caused by γ-radiation originating from the uranium and thorium series and 40K. In this study, the gamma radiation has been measured to determine natural radioactivity of 238U, 232Th, and 40K in collected sedimentary rock samples in different places of Turkey. The measurements have been performed using γ-ray spectrometer containing NaI(Tl detector and multichannel analyser (MCA. Absorbed dose rate (D, annual effective dose (AED, radium equivalent activities (Raeq, external hazard index (Hex, and internal hazard index (Hin associated with the natural radionuclide were calculated to assess the radiation hazard of the natural radioactivity in the sedimentary rock samples. The average values of absorbed dose rate in air (D, annual effective dose (AED, radium equivalent activity (Raeq, external hazard index (Hex, and internal hazard index (Hin were calculated and these were 45.425 nGy/h, 0.056 mSv/y, 99.014 Bq/kg, 0.267, and 0.361, respectively.

  3. Benthic cyanobacteria and their influence on the sedimentary dynamics of peritidal depositional systems (siliciclastic, evaporitic salty, and evaporitic carbonatic)

    Science.gov (United States)

    Noffke, Nora; Gerdes, Gisela; Klenke, Thomas

    2003-07-01

    Peritidal sedimentary systems are widely colonized by benthic cyanobacteria that form biofilms and microbial mats. The bacterial communities interfere with physical and chemical sedimentary dynamics, which is documented by the formation of Microbially Induced Sedimentary Structures (MISS). The structures form a new fifth category in the existing Classification of Primary Sedimentary Structures. Siliciclastic depositional systems are dominated by physical dynamics. By biostabilization, cyanobacteria shelter their substrata against erosion during periods of intensive hydraulic reworking, or they permit flexible deformation of sandy sediments. During low hydrodynamic disturbance, the bacteria enhance deposition of sediments by baffling, trapping, and binding. Such biotic-physical interference is recorded by MISS such as erosional remnants and pockets or planar stromatolites. Chemical depositional systems include (i) evaporitic salty environments characterized by evaporation and dissolution and (ii) evaporitic carbonatic environments that include evaporation, dissolution, and in situ lithification of organic matter. Here, cyanobacterial mats experience periodical desiccation or evaporation of crystals and mat-related structures such as petees, and polygonal patterns of cracks are formed. Cyanobacteria and heterotrophic bacteria provide a chemical microenvironment that supports in situ lithification of organic matter. In thin-sections, carbonate precipitates as ooids or lines of decaying filaments are visible. MISS occur in modern and ancient depositional systems. They record (i) biological abilities of benthic cyanobacteria to cope with sedimentary dynamics and (ii) paleoclimate and paleoenvironmental conditions during Earth history. Similar structures are also expected in extraterrestrial (paleo)environments.

  4. Study on the relationship between the sedimentary subfacies and the sandstone uranium deposit mineralization in the belt of Shihongtan uranium deposit

    International Nuclear Information System (INIS)

    For identification the relationship between the sedimentary subfacies and the sandstone uranium deposit mineralization, the all drill hole data in the north belt of Shihongtan uranium deposit is arranged, the depositional sys- tem and sedimentary subfacies of ledge is established. Based on the depositional system and sedimentary subfacies controlled on the ground water direction, interlayer oxidization zone shape and uranium mineral ore shape are researched, that the interlayer oxidization zone shape and uranium mineral ore shape are completely controlled By the sedimentary subfacies the sedimentary subfacies is fount out and the significance of researching on the depositional system and the sedimentary subfacies in the Uranium deposit exploration is put out. In the conclusion the paper point out that survey project is arranged directed by the depositional system could acquire obvious result. (authors)

  5. Elemental Characteristics of Australian Sedimentary Opals and their Implications for Opal Formation and Gemstone Fingerprinting

    Science.gov (United States)

    Dutkiewicz, A.; Landgrebe, T. C.; Rey, P. F.

    2011-12-01

    Opal consists of amorphous SiO2.nH2O comprising a network of silica spheres, which in precious opal are of similar size and form an ordered network allowing light to diffract into an array of colors. Common opal, which is often associated with precious opal, lacks this play of color as it is composed of silica spheres of variable sizes. Australia supplies over 95% of the world's precious opal. The opal is almost exclusively located within Cretaceous sedimentary rocks of the Great Artesian Basin, which experienced a major phase of uplift in the Late Cretaceous with subsequent erosion removing a package of sedimentary rock up to 3 km in thickness. Intense weathering resulted in extensive silicification at relatively shallow levels within the Tertiary regolith. However, despite a billion dollar industry and a well-constrained geological history of the basin, the formation of sedimentary opal and its uniqueness to the Australian continent are still very poorly understood. In this study we have used laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) on precious and common opal from key opal mining areas in order to constrain the possible sources of silica fluids involved in opal genesis and to assess whether any major or trace elements could be used to determine the provenance of opal with respect to a particular mining area. A total of 123 spots, each comprising 59 elements, including rare earth elements were analyzed. Globally, volcanic and sedimentary opals can be distinguished on the basis of Ba and Ca concentrations. Although the opals from the Great Artesian Basin are all sedimentary, some show Ba concentrations consistent with volcanic opals suggesting that silica fluids from which they formed were derived from a volcanic province. The most likely source is the Cretaceous volcanic-plutonic province of central Queensland, which supplied vast amounts of volcanogenic material into the Great Artesian Basin. The weathering of feldspars from the

  6. Chemostratigraphy of early Neoproterozoic sedimentary rocks of Yenisei ridge (Siberia, Russia)

    Science.gov (United States)

    Vishnevskaya, Irina; Pisareva, Natalia; Kanygina, Nadejda; Proshenkin, Artem

    2014-05-01

    One of the biggest Proterozoic sedimentary basins in Russia is around the Siberian platform. This study about little part of them - Neoproterozoic sedimentary rocks of Yenisei ridge (Southwestern margin of Siberian Platform). Thise geological structure is ancient and very difficult for reaserch. It is a collage of different blocks: volcanic arcks, ophiolite complexes and sedimentary rocks of various ages and degrees of metamorphism. Sedimentary complexes of Siberian platform are outcropping along Angara River and its tributary. Neoproterozoic ones are presented by terrigenous-carbonate rocks of Tungusik and Oslyan groups. Despite the long study history of the area is still controversial question of time of formation of these rocks. As determination of the age of Precambrian sedimentary rocks is very difficult, Sr isotopic chemostratigraphy appears to be the only approach to establish the age of carbonate sequences. All Rb-Sr author's data was investigated by the method of selective dissolution with the preliminary removal of epigenetic carbonate phases. The isotope dilution method with mixed 87Rb + 84Sr spike was used to determine Rb and Sr concentrations in both fractions on the MI 1201AT mass spectrometer. Sr isotope ratios were measured on the Finnigan MAT-262 (BAC CU, Irkutsk, Russia) and Triton Plus (IGG UB RAS, Ekaterinburg, Russia). The C-O isotopic composition in carbon samples was measured on the Finnigan MAT-253 equipment. The main criteria for integrity were correlations of impurity-elements (Mn, Fe, Sr) and stable isotopes (C, O) with each other. The less altered rocks of the Tungusik Group are characterized by 87Sr/86Sr ratio of 0.7055-0.7058, and wide variations in the δ13CPDB values from 0 to +5o [1]. The primary 87Sr/86Sr of Dashka Formation (Oslyan Group) is 0.7057 - 0.7060 and δ13CPDB value varies in interval 3.7-4.3o like in upper part of Tungusik Group. High positive values of δ13CPDB indicate that carbonates had accumulated in warm sea

  7. Extreme events in the sedimentary record of maar Lake Pavin: Implications for natural hazards assessment in the French Massif Central

    Science.gov (United States)

    Chassiot, Léo; Chapron, Emmanuel; Di Giovanni, Christian; Albéric, Patrick; Lajeunesse, Patrick; Lehours, Anne-Catherine; Meybeck, Michel

    2016-06-01

    A set of sedimentary cores, high resolution swath bathymetry and subbottom profiler data provides new insights on sedimentary processes in meromictic maar Lake Pavin, France. Three sedimentary environments (i.e., littoral, plateau and basin) have been identified in the lake from sediment composition using bulk organic geochemistry and the analysis of hydroacoustic images. Various forms of rapidly deposited layers (RDLs) have been identified and radiocarbon dated. An up to date stratigraphy of sedimentary events matching coeval RDLs across the lake is presented and illustrates a wide range of natural hazards linked to Lake Pavin during the last 2000 years. In AD 600, a sudden lake outburst triggered a slump deposit along with a 9 m lake-level drop that drove shifts in sedimentary organic matter composition. Outside the lake, outburst flood deposits have been described downstream and provide sedimentary evidence for this event. The lake-level drop also favored the generation of gravity reworking processes, as shown by (1) a regional earthquake-triggered large slope failure on the plateau connected to a mass-wasting deposit in the basin dated to AD 1300, and (2) a succession of turbidites in AD 1825 and AD 1860 contemporaneous to two historic earthquakes, suggesting that this lake is sensitive to earthquakes with a minimum epicentral intensity of V. Finally, past observations of lake water color changes in AD 1783 and AD 1936, similar to reports in other meromictic lakes, match iron-rich deposits identified in maar lake sediments and suggest that Lake Pavin could have undergone limnic eruptions.

  8. Ecosystem development following deglaciation: A new sedimentary record from Devils Lake, Wisconsin, USA

    Science.gov (United States)

    Williams, Joseph J.; McLauchlan, Kendra K.; Mueller, Joshua R.; Mellicant, Emily M.; Myrbo, Amy E.; Lascu, Ioan

    2015-10-01

    Processes and rates of ecosystem development can be reconstructed using lacustrine sedimentary sequences, but this approach often requires records that contain the start of primary succession. Most lakes in the upper Midwestern U.S. were formed by glaciers at the end of the last Ice Age approximately 11,700 cal yr BP. Devils Lake, Wisconsin is a rare example of a lake from this region whose sediments extend into the Pleistocene and may include the Last Glacial Maximum. Sediment magnetic, geochemical, pollen, and charcoal records were generated from a 10 m core whose basal sediments may be 28,000 years old. Together with a previously published pollen record, these proxies combine to reveal a history of long-term climatic, vegetative and geologic change during the late Pleistocene to Holocene. We identify six sedimentary units that indicate a series of consecutive events rather than a predictable trajectory of ecosystem development at the site. Productivity in the lake was low during the late Pleistocene and increased during the Holocene, as reflected by the sediment lithology, which shows a sudden shift from glacial vivianite-rich and organic-poor clastic-dominated sediments to Holocene diatomaceous sapropels. Several important processes initiated around 17,000 cal yr BP, including the onset of organic matter accumulation and fire in the terrestrial ecosystem. However, the post-glacial landscape was not devoid of vegetation because pollen assemblages indicate that terrestrial vegetation, likely a spruce tundra, survived near the site. A switch to a hardwood forest period during the Holocene also led to a change in the fire regime, with increased frequency of burning. Aquatic ecosystem productivity lagged terrestrial ecosystem productivity throughout the record. Nutrient cycling (as recorded by sedimentary δ15N) was variable but not directional, and appeared to be correlated with climate conditions early in the record, and terrestrial ecosystem processes later in

  9. Palynostratigraphy and sedimentary facies of Middle Miocene fluvial deposits of the Amazonas Basin, Brazil

    Science.gov (United States)

    Dino, Rodolfo; Soares, Emílio Alberto Amaral; Antonioli, Luzia; Riccomini, Claudio; Nogueira, Afonso César Rodrigues

    2012-03-01

    Palynostratigraphic and sedimentary facies analyses were made on sedimentary deposits from the left bank of the Solimões River, southwest of Manaus, State of Amazonas, Brazil. These provided the age-dating and subdivision of a post-Cretaceous stratigraphic succession in the Amazonas Basin. The Novo Remanso Formation is subdivided into upper and lower units, and delineated by discontinuous surfaces at its top and bottom. The formation consists primarily of sandstones and minor mudstones and conglomerates, reflecting fluvial channel, point bar and floodplain facies of a fluvial meandering paleosystem. Fairly well-preserved palynoflora was recovered from four palynologically productive samples collected in a local irregular concentration of gray clay deposits, rich in organic material and fossilized wood, at the top of the Novo Remanso Formation upper unit. The palynoflora is dominated by terrestrial spores and pollen grains, and is characterized by abundant angiosperm pollen grains ( Tricolpites, Grimsdalea, Perisyncolporites, Tricolporites and Malvacearumpollis). Trilete spores are almost as abundant as the angiosperm pollen, and are represented mainly by the genera Deltoidospora, Verrutriletes, and Hamulatisporis. Gymnosperm pollen is scarce. The presence of the index species Grimsdalea magnaclavata Germeraad et al. (1968) indicates that these deposits belong to the Middle Miocene homonymous palynozone (Lorente, 1986; Hoorn, 1993; Jaramillo et al., 2011). Sedimentological characteristics (poorly sorted, angular to sub-angular, fine to very-coarse quartz sands facies) are typical of the Novo Remanso Formation upper part. These are associated with a paleoflow to the NE-E and SE-E, and with an entirely lowland-derived palinofloristic content with no Andean ferns and gymnosperms representatives. All together, this suggests a cratonic origin for this Middle Miocene fluvial paleosystem, which was probably born in the Purus Arch eastern flank and areas surrounding the

  10. Spatial Distribution and Sedimentary Facies of the 2007 Solomon Islands Tsunami Deposits

    Science.gov (United States)

    Nakamura, Y.; Nishimura, Y.; Woodward, S.

    2007-12-01

    We conducted a field survey of the extent of damage, crustal deformation, and onshore deposits caused by 2007 Solomon Islands tsunami in Ghizo and adjacent islands in the western Solomon Islands, from 13th to 18th April, 2007. Our survey team was comprised of six Japanese and one American researcher. Three of us, the authors, mainly investigated tsunami deposits in three villages (Titiana, Suva, and Pailongge) in southern Ghizo Island. One member of our team re-investigated the deposits in June 2007. The tsunami generated sheet-like deposits of coral beach sand on the flat plain in Titiana. Beside the sea coast, the tsunami wave eroded ground surfaces and formed small scarps at 30 m from the sea. Just interior of the scarps, tsunami deposits accumulated up to 9 cm in thickness. The thickness decreased with distance from the sea and was also affected by microtopography. No sandy tsunami deposits were observed on the inland area between 170 m and 210 m from the sea. The upper boundary of inundation was recognized at about 210 m from the sea because of accumulation of driftwood and floating debris. In Suva and Pailongge, the outline of sand-sheet distribution is the same as it in Titiana. The tsunami had a maximum thickness of 10 cm and two or three sand layers are separated by thin humic sand layers. These humic layers were likely supplied from hillslopes eroded by the tsunami and transported by return-flows. These successions of deposits suggest that tsunami waves inundated at least two times. This is consistent with the number of large waves told by eyewitnesses. In the Solomon Islands, the plentiful rainfall causes erosion and resedimentation of tsunami deposits. Furthermore, the sedimentary structures will be destroyed by chemical weathering in warm and moist environment, and bioturbation by plants, animals, and human activities. The sedimentary structures had been preserved till the end of June 2007, but had already been penetrated by plant roots and sandpipes

  11. Transfer and mobility of trace metallic elements in the sedimentary column of continental hydro-systems

    International Nuclear Information System (INIS)

    In freshwater systems, trace metal pollutants are transferred into water and sedimentary columns under dissolved forms and/or fixed onto solid particles. Accumulated in the sedimentary areas, these latter ones can constitute important stocks of materials and associated pollutants and may impair water quality when environmental changes lead to increase their mobility. The mobility of the stocks of pollutants is mainly depending on the erosion, on the interstitial diffusion of the mobile phases (dissolved and colloidal) and on the bioturbation. In this context, this study involves the analysis of the mobility by interstitial diffusion. This topic consists in studying trace metal fractionation between their mobile (dissolved and colloidal) and non mobile (fixed onto the particles) forms. This point is governed by sorption/desorption processes at the particle surfaces. These processes are regulated by physico-chemical parameters (pH, redox potential, ionic strength...) and are influenced by biogeochemical reactions resulting from the oxidation of the organic matter by the microbial activity. These reactions generate vertical profiles of nutrients and metal concentrations along the sedimentary column. To understand these processes, this work is based on a mixed approach that combines in situ, analysis and modelling. In situ experimental part consists in sampling natural sediments cores collected at 4 different sites (1 site in Durance and 3 sites on the Rhone). These samples are analyzed according to an analytical protocol that provides the vertical distribution of physicochemical parameters (pH, redox potential, size distribution, porosity), nutrients and solid - liquid forms of trace metals (cobalt, copper, nickel, lead, zinc). The analysis and interpretation of these experimental results are based on a model that was developed during this study and that includes: 1) model of interstitial diffusion (Boudreau, 1997), 2) biogeochemical model (Wang and Van Cappellen

  12. Sedimentary and mineral dust sources of dissolved iron to the World Ocean

    Directory of Open Access Journals (Sweden)

    J. K. Moore

    2007-04-01

    Full Text Available A worldwide database of dissolved iron observations is used to improve simulations of the marine iron cycle within a global-scale, Biogeochemical Elemental Cycling (BEC ocean model. Modifications to the model include: 1 an improved particle scavenging parameterization based on the sinking mass flux of particulate organic material, biogenic silica, calcium carbonate, and mineral dust particles; 2 desorption of dissolved iron from sinking particles; and 3 an improved sedimentary source for dissolved iron. Most scavenged iron (90% is put on sinking particles to remineralize deeper in the water column. The model-observation mismatches are greatly reduced both in surface waters and in the deeper ocean. Inclusion of desorption has little effect on surface water iron concentrations where adsorption/scavenging is strongly dominant, but significantly increases simulated iron concentrations in the deep ocean. Our results suggest that there must be substantial removal of dissolved iron from subsurface waters (where iron concentrations are <0.6 nM in most regions to match observed distributions. Aggregation and removal on sinking particles of Fe bound to organic colloids is a likely mechanism.

    The improved BEC model is used to address the relative contributions of mineral dust and marine sediments in driving ocean productivity and observed dissolved iron distributions. The sedimentary iron source from the continental margins has a strong impact on open ocean iron concentrations, particularly in the North Pacific. Plumes of elevated dissolved iron concentrations develop at depth in the Southern Ocean, extending from source regions in the SW Atlantic and around New Zealand. The lower particle flux and weaker scavenging in this region allows the continental iron source to be advected far from source areas. Both the margin sediment and mineral dust Fe sources significantly impact global scale primary production, export production, and nitrogen fixation

  13. Studying the NE Eridania sedimentary sequence through the Mars 2020 rover

    Science.gov (United States)

    Pajola, M.; Carter, J.; Rossato, S.; Baratti, E.; Mangili, C.; Coradini, M.; McBride, K. S.

    2014-04-01

    The landing sites we are proposing for the next Mars 2020 rover span between 28°29'30"S-28°53'0"S Latitude and 178°56'30"W°178°28'0"W Longitude, i.e. on the NE floor of a 1.1×106 km2 closed drainage basin [1]. This area, see Fig. 1, belongs to the bigger (3×106 km2) Eridania basin that gave birth to the Ma'adim Vallis through catastrophic overflow, and presenting a water table between 950 and 1250 m [1,2,3]. The crater counting chronology for this area gives an age between Early to Middle Noachian [4]. By means of OMEGA [5] and CRISM [6] data, a large clay-bearing sedimentary unit has been identified over almost the entire margin of the Eridania basin [7]. On our specific site, i.e. the NE margin of the Eridania basin, sequences of aqueous minerals are observed. Such sedimentary minerals are accessible through erosional windows into the first several tens of meters of the sedimentary sequence. The top-down mineral sequence identified on the landing sites area presents an unaltered capping unit that is overlying an Al-rich clay stratum (see Fig. 2) akin to Al-smectite and/or kaolins with a 3.8 Ga) during which liquid water was durably stable at the surface. The most valuable candidates for ancient Martian microbial life sustainability and preservation are longlasting environments, characterized by the presence of ponding water [10,11,12]: hence, the proposed site presents a high exobiological potential that is just waiting to be unveiled. Besides that, when putting into context the future results on Eridania Basin, i.e. the Ma'adim Vallis source, together with those obtained from the Spirit rover inside Gusev Crater (see Fig. 1), i.e. the Ma'adim Vallis mouth, a wide understanding of this intriguing canyon and of the Mars megaflooding age is foreseen. Besides the above scientific analysis showing than the NE side of the Eridania region fulfills entirely the Mars 2020 scientific requirements [13], the location of the proposed landing sites widely meets all the

  14. Main Controlling Factors on Hydrocarbon Accumulation and Distribution in Marine Sedimentary Sequences in South China

    Institute of Scientific and Technical Information of China (English)

    Cai Liguo; Zhou Yan; Bai Zhenrui

    2008-01-01

    Multiple source rock assemblages were deposited in the sedimentary provinces in South China in geologic history,and some of them were destructed by and some survived against multiple tectonic movements.Therefore,multiple sources,mixed sources,and uneven distribution of sources occurred in the marine sedimentary basins in South China during the late stage of hydrocarbon pooling.Epidiagenesis of the marine carbonate reservoirs and its modification to reservoir poroperm characteristics determined the formation and the scale of natural gas pools.The exploration practices show that the large to medium gas fields mainly occur in areas with high-quality reservoirs.Detailed study of the paleo-oil accumulations and typical oil and gas reservoirs reveals that the basins experienced multiphase superimposition and modification,leading to the distribution of the Paleozoic paleo-oil accumulations and bitumen in the peripheral areas.The phenomenon that oil and gas production concentrates in the Sichuan basin indicates that the overall sealing conditions of a basin determine the oil/gas potentials and the scale of oil and gas production.This is a critical factor controlling the accumulation and distribution of gas in the marine sequences in South China.The early oil and gas pools in the Yangtze platform left billions of bitumen in the peripheral areas due to the destruction of seals.Since the Himalayan,"late-generation and late-accumulation" gas pools represented by the gas pools in the Sichuan (四川) basin were formed in the marine sedimentary sequences in South China as a result of the change of the sealing conditions.Current gas discoveries appear to be "paleo-generation and paleo-accumulation" gas pools but actually are "late-generation and late-accumulation" gas pools.These patterns of hydrocarbon pooling clearly depict themselves in western Sichuan basin and Weiyuan (威远)gas field.It is revealed that the gas pools in the Sichuan basin were mainly formed as a result of

  15. Recording of climate and diagenesis through fossil pigments and sedimentary DNA at Laguna Potrok Aike, Argentina

    Science.gov (United States)

    Vuillemin, A.; Ariztegui, D.; Leavitt, P. R.; Bunting, L.; Pasado Science Team

    2015-11-01

    Aquatic sediments record past climatic conditions while providing a wide range of ecological niches for microorganisms. Although marine sedimentary microbial assemblages are often defined by their surrounding geochemical conditions, the influence of environmental features upon microbial development and post-depositional survival remains largely unknown in the lacustrine realm. Due to long-term microbial activity, the composition of environmental DNA can be expected to evolve with sediment depth and over time and therefore should reflect both ancient and extant microbial populations, but this hypothesis has rarely been tested using a multiproxy approach. Here geomicrobiological and phylogenetic analyses of a Patagonian maar lake were used to indicate that the different sedimentary microbial assemblages derive from specific lacustrine regimes during defined climatic periods. Two well defined climatic intervals whose sediments harboured active microbial populations and measurable ATP were sampled for a comparative environmental study based on fossil pigments and 16S rRNA gene sequences. Bacterial and archaeal 16S rRNA gene sequences recovered from the Holocene record revealed a microbial community adapted to subsaline conditions actively producing methane during organic matter degradation. These characteristics were associated with sediments resulting from endorheic lake conditions with high evaporative stress and concomitant high algal productivity. Moreover, archaeal clone libraries established throughout the Holocene record indicate an age-related stratification of these populations, consistent with a gradual use of organic substrates after deposition. In contrast, sulphate-reducing bacteria and lithotrophic Archaea were predominant in sediments dated from the Last Glacial Maximum, in which pelagic clays alternated with fine volcanic material characteristic of a lake level highstand and freshwater conditions, but reduced water column productivity. These patterns

  16. Holocene paleoclimate characterization in Lago Fagnano (Tierra del Fuego) using sedimentary, physical and geochemical proxies

    Science.gov (United States)

    Vizcaino Marti, A.; Dunbar, R. B.; Wahl, D.; Moy, C. M.; Mucciarone, D. A.; Anderson, L.; Guilderson, T. P.

    2010-12-01

    Tierra del Fuego is the world's southernmost landmass outside of Antarctica. Two features of ocean circulation control the climate of Tierra del Fuego: the Southern Ocean circumpolar flow and the South Pacific Gyre. Together with Patagonia, Tierra del Fuego is the only terrestrial region directly influenced by the southern hemisphere westerly winds. This region is also a tectonically active area affected by volcanic and seismic activity related to South American and Scotia-Antarctic plate boundaries. Accommodated along the Magallanes-Fagnano fault system, as part of the plate boundary, the Lago Fagnano is the largest lake in Tierra del Fuego. This E-W trending lake is 100 km long and 5-15 km wide. Our investigations were carried out on the upper 4 meters of an 8.4 m long piston core obtained at 69 m water depth in Bahía Grande (LF06-PC8); a southwestern lake sub-basin separated from the main lake by a shallow sill. Our studies are based on the integration of sediment description, physical properties, pollen, and geochemical analyses including C and N isotopes (1cm interval) and XRF scan (1mm interval). The age model for the core is based on radiocarbon ages and tephrochronology. Additionally, a 800 km long grid of high resolution seismic profiles support the sedimentary analyses and allow the correlation with other cores from within the lake basin. LF06-PC8 yields continuous and high accumulation-rate sedimentary sections for Lago Fagnano. The presented sediment record corresponds to a laminated hemipelagite with presence of a single but complex mass transport deposit interval. An accurate sedimentological interpretation of the core together with the radiocarbon ages and tephra dates allow to identify and characterize the main sedimentary processes occurring in the lake over the last 8 kyr. In addition, proxy data (C and N isotopes and XRF scan data) from the laminated hemipelagic interval provide a reliable record of past variability in the westerly wind field as

  17. Distribution, Character, and Importance of Sedimentary Furrows in South-Central Long Island Sound

    Science.gov (United States)

    Poppe, L.; Doran, E.; Moser, M.; Forfinski, N.; Stewart, H.; Gardner, U.; Keene, J.; Christman, E.; Ackerman, S.

    2005-05-01

    The U.S. Geological Survey, in cooperation with the Connecticut Department of Environmental Protection and the National Oceanic and Atmospheric Administration, is producing detailed geologic interpretations of the sea floor in Long Island Sound to improve our understanding of the processes that control the complex distributions of sedimentary environments and benthic habitats. Although the deeper waters of the south-central Sound are generally characterized by relatively weak bottom currents and by depositional conditions, multibeam data reveal the presence of sedimentary furrows. These erosional bedforms occur in fine-grained cohesive sediments and cover an elongate east-west trending area (~80 km2) that lies approximately 5 km off Herod Point, NY, in water depths of 31-41 m. The furrows are irregularly spaced, trend east-northeast, average 9 m wide and 0.4 m deep, and can exceed 1.9 km long. Although most of the furrows appear to taper out gradually, some furrows show a "tuning fork" joining pattern. Most of these junctions open toward the east, indicating net westward sediment transport, but a few junctions open westward suggesting that the tidal regime is important to furrow formation and that the furrows can form when water flows in either direction. The sedimentary furrows in south-central Long Island Sound, which are similar to those we have previously described along the Connecticut side of the estuary, form under recurring directionally stable tidal currents, constrained by the elongate geometry and regional bathymetry of the Sound. These conditions, in turn, produce the secondary helical and turbulent flow patterns conducive to the formation of erosional furrows. Concurrently, bioturbation by crabs not only suspends sediment, but also nutclam shells and other coarse biogenic debris, which are aligned by the secondary flow and abrade the furrows as they saltate in the oscillating tides. Through resuspension due to biological activity and the subsequent

  18. Heterogeneous arsenic enrichment in meta-sedimentary rocks in central Maine, United States

    Energy Technology Data Exchange (ETDEWEB)

    O' Shea, Beth, E-mail: bethoshea@sandiego.edu [Department of Marine Science and Environmental Studies, University of San Diego, 5998 Alcala Park, San Diego, CA 92110 (United States); Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, NY 10964 (United States); Stransky, Megan; Leitheiser, Sara [Department of Marine Science and Environmental Studies, University of San Diego, 5998 Alcala Park, San Diego, CA 92110 (United States); Brock, Patrick [School of Earth and Environmental Sciences, Queens College, City University of New York, 65-30 Kissena Blvd., Flushing, NY 11367 (United States); Marvinney, Robert G. [Maine Geological Survey, 93 State House Station, Augusta, ME 04333 (United States); Zheng, Yan [School of Earth and Environmental Sciences, Queens College, City University of New York, 65-30 Kissena Blvd., Flushing, NY 11367 (United States); Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, NY 10964 (United States)

    2015-02-01

    Arsenic is enriched up to 28 times the average crustal abundance of 4.8 mg kg{sup −1} for meta-sedimentary rocks of two adjacent formations in central Maine, USA where groundwater in the bedrock aquifer frequently contains elevated As levels. The Waterville Formation contains higher arsenic concentrations (mean As 32.9 mg kg{sup −1}, median 12.1 mg kg{sup −1}, n = 38) than the neighboring Vassalboro Group (mean As 19.1 mg kg{sup −1}, median 6.0 mg kg{sup −1}, n = 38). The Waterville Formation is a pelitic meta-sedimentary unit with abundant pyrite either visible or observed by scanning electron microprobe. Concentrations of As and S are strongly correlated (r = 0.88, p < 0.05) in the low grade phyllite rocks, and arsenic is detected up to 1944 mg kg{sup −1} in pyrite measured by electron microprobe. In contrast, statistically significant (p < 0.05) correlations between concentrations of As and S are absent in the calcareous meta-sediments of the Vassalboro Group, consistent with the absence of arsenic-rich pyrite in the protolith. Metamorphism converts the arsenic-rich pyrite to arsenic-poor pyrrhotite (mean As 1 mg kg{sup −1}, n = 15) during de-sulfidation reactions: the resulting metamorphic rocks contain arsenic but little or no sulfur indicating that the arsenic is now in new mineral hosts. Secondary weathering products such as iron oxides may host As, yet the geochemical methods employed (oxidative and reductive leaching) do not conclusively indicate that arsenic is associated only with these. Instead, silicate minerals such as biotite and garnet are present in metamorphic zones where arsenic is enriched (up to 130.8 mg kg{sup −1} As) where S is 0%. Redistribution of already variable As in the protolith during metamorphism and contemporary water–rock interaction in the aquifers, all combine to contribute to a spatially heterogeneous groundwater arsenic distribution in bedrock aquifers. - Highlights: • Arsenic is enriched up to 138 mg kg

  19. Heterogeneous arsenic enrichment in meta-sedimentary rocks in central Maine, United States

    International Nuclear Information System (INIS)

    Arsenic is enriched up to 28 times the average crustal abundance of 4.8 mg kg−1 for meta-sedimentary rocks of two adjacent formations in central Maine, USA where groundwater in the bedrock aquifer frequently contains elevated As levels. The Waterville Formation contains higher arsenic concentrations (mean As 32.9 mg kg−1, median 12.1 mg kg−1, n = 38) than the neighboring Vassalboro Group (mean As 19.1 mg kg−1, median 6.0 mg kg−1, n = 38). The Waterville Formation is a pelitic meta-sedimentary unit with abundant pyrite either visible or observed by scanning electron microprobe. Concentrations of As and S are strongly correlated (r = 0.88, p < 0.05) in the low grade phyllite rocks, and arsenic is detected up to 1944 mg kg−1 in pyrite measured by electron microprobe. In contrast, statistically significant (p < 0.05) correlations between concentrations of As and S are absent in the calcareous meta-sediments of the Vassalboro Group, consistent with the absence of arsenic-rich pyrite in the protolith. Metamorphism converts the arsenic-rich pyrite to arsenic-poor pyrrhotite (mean As 1 mg kg−1, n = 15) during de-sulfidation reactions: the resulting metamorphic rocks contain arsenic but little or no sulfur indicating that the arsenic is now in new mineral hosts. Secondary weathering products such as iron oxides may host As, yet the geochemical methods employed (oxidative and reductive leaching) do not conclusively indicate that arsenic is associated only with these. Instead, silicate minerals such as biotite and garnet are present in metamorphic zones where arsenic is enriched (up to 130.8 mg kg−1 As) where S is 0%. Redistribution of already variable As in the protolith during metamorphism and contemporary water–rock interaction in the aquifers, all combine to contribute to a spatially heterogeneous groundwater arsenic distribution in bedrock aquifers. - Highlights: • Arsenic is enriched up to 138 mg kg−1 in meta-sedimentary rocks in central Maine.

  20. Radiogenic isotope systematics of clastic sedimentary rocks - with emphasis on detrital zircon geochronology

    International Nuclear Information System (INIS)

    In the present study, the radiogenic isotope systematics of clastic sedimentary rocks are applied to provenance studies. Provenance means place of origin and is basically focused on the location and nature of sediment source areas, the pathways by which the eroded material is transferred from the source to the basin of deposition, and the factors that influence the composition of sedimentary rocks (e.g. relief, climate, tectonic setting). ICP-MS has revolutionised analytical trace element geochemistry, and micro-sampling by laser ablation makes it possible to analyse the trace element and isotope compositions of detrital mineral grains. At the time when this study was initiated, a few pilot studies on detrital zircon geochronology had been carried out. The higher sample throughput and the lower investment cost of 1CPMS compared to SIMS instrumentation, were clear advantages. The analytical challenge was to improve the lower accuracy and precision of the technique. However, new correction methods had shown promising results when applied to the analyses of zircon standards. A careful comparison of the LA-ICPMS with the SIMS technique was needed before LA-ICPMS could confidently be used for provenance studies. A comparative study of' the two techniques was therefore carried out using the NORDSIM facility and the ICPMS laboratory at Memorial University of Newfoundland. The first paper of this thesis deals with the LA-ICPMS technique, and the accuracy and precision of the method when applied to detrital zircon dating. The subsequent papers present three case studies that use the technique, 1) as a tool for terrane analyses of orogenic belts; 2) for provenance studies of a molasse basin to constrain late orogenic exhumation history; and 3) to study the provenance of offshore sediments. 4 papers are included and have titles: 1) U-Pb dating of detrital zircons for sediment provenance studies -a comparison of laser ablation ICPMS and SIMS techniques. 2) U-Pb zircon and Sm

  1. Sedimentary organic matter variations in the Chukchi Borderland over the last 155 kyr

    Directory of Open Access Journals (Sweden)

    S. F. Rella

    2011-03-01

    Full Text Available Knowledge on past variability of sedimentary organic carbon in the Arctic Ocean is important to assess natural carbon cycling and transport processes related to global climate changes. However, the late Pleistocene oceanographic history of the Arctic is still poorly understood. In the present study we show sedimentary records of total organic carbon (TOC, C/N and CaCO3 from a piston core recovered from the northern Northwind Ridge in the far western Arctic Ocean, a region potentially sensitively responding to past variability in surface current regimes and sedimentary processes such as coastal erosion. An age model based on correlation of our CaCO3 record with the benthic δ18O stack, supplemented by lithological constraints, suggests that the piston core records paleoenvironmental changes of the last 155 kyr. According to this age model, TOC and C/N show orbital-scale increases and decreases that can be respectively correlated to the waxing and waning of large ice sheets dominating the Eurasian Arctic, suggesting advection of fine suspended matter derived from glacial erosion to the Northwind Ridge by eastward flowing intermediate water and/or surface water and sea ice during cold episodes of the last two glacial-interglacial cycles. At millennial scales, increases in TOC and C/N appear to correlate to a suite of Dansgaard-Oeschger Stadials between 120 and 40 ka before present (BP and thus seem to respond to abrupt northern hemispheric temperature changes. Between 65 and 40 ka BP, closures and openings of the Bering Strait could have additionally influenced TOC and C/N variability. CaCO3 content tends to anti-correlate with TOC and C/N on both orbital and millennial time scales, which we interpret as enhanced sediment advection from the carbonate-rich Canadian Arctic via an extended Beaufort Gyre during warm periods of the last two glacial-interglacial cycles and increased terrestrial organic carbon

  2. Derivation of S and Pb in phanerozoic intrusion-related metal deposits from neoproterozoic sedimentary pyrite, Great Basin, United States

    Science.gov (United States)

    Vikre, P.G.; Poulson, S.R.; Koenig, A.E.

    2011-01-01

    The thick (???8 km), regionally extensive section of Neoproterozoic siliciclastic strata (terrigenous detrital succession, TDS) in the central and eastern Great Basin contains sedimentary pyrite characterized by mostly high d34S values (-11.6 to 40.8%, Pb isotopes ( 207Pb/204Pb Pb-Zn-Cu-Ag-Au deposits associated with Jurassic, Cretaceous, and Tertiary granitic intrusions (intrusion-related metal deposits) contain galena and other sulfide minerals with S and Pb isotope compositions similar to those of TDS sedimentary pyrite, consistent with derivation of deposit S and Pb from TDS pyrite. Minor element abundances in TDS pyrite (e.g., Pb, Zn, Cu, Ag, and Au) compared to sedimentary and hydrothermal pyrite elsewhere are not noticeably elevated, implying that enrichment in source minerals is not a precondition for intrusion-related metal deposits. Three mechanisms for transferring components of TDS sedimentary pyrite to intrusion-related metal deposits are qualitatively evaluated. One mechanism involves (1) decomposition of TDS pyrite in thermal aureoles of intruding magmas, and (2) aqueous transport and precipitation in thermal or fluid mixing gradients of isotopically heavy S, radiogenic Pb, and possibly other sedimentary pyrite and detrital mineral components, as sulfide minerals in intrusion-related metal deposits. A second mechanism invokes mixing and S isotope exchange in thermal aureoles of Pb and S exsolved from magma and derived from decomposition of sedimentary pyrite. A third mechanism entails melting of TDS strata or assimilation of TDS strata by crustal or mantle magmas. TDS-derived or assimilated magmas ascend, decompress, and exsolve a mixture of TDS volatiles, including isotopically heavy S and radiogenic Pb from sedimentary pyrite, and volatiles acquired from deeper crustal or mantle sources. In the central and eastern Great Basin, the wide distribution and high density of small to mid-sized vein, replacement, and skarn intrusion-related metal deposits

  3. TECTONIC ZONING OF THE SEDIMENTARY COVER OF THE SEA OF OKHOTSK BASED ON LITHOPHYSICAL, STRUCTURAL AND STRUCTURAL-LITHOPHYSICAL INDICATORS

    Directory of Open Access Journals (Sweden)

    V. P. Semakin

    2015-09-01

    Full Text Available In terms of tectonics, the Sea of Okhotsk (Fig.1 is the epi-Mesozoic Okhotsk plate comprising the heterogeneous basement that is mainly pre-Cenozoic (the lower structural stage and the sedimentary cover that is mainly represented by the Paleogenic-Neogenic-Quaternary deposits with the Upper Cretaceous sedimentary rocks observed locally without a visible hiatus (the upper structural stage.Results of tectonic zoning of the sedimentary cover based on  lithophysical indicators (Fig. 2 are represented in the format of maps showing lithophysical complexes (LC within the limits of four regional seismo-stratigraphic complexes/structural layers (RSSC I-IV corresponding to the following time intervals: the pre-Oligocene К2-P1-2 (RSSC I, the Oligocene – Lower Miocene P3-N11 (RSSC II, the Lower-Mid Miocene N11-2 (RSSC III, and the Upper Miocene – Pliocene N13-N2 (RSSC IV. Diverse lithological-facies associations composing the RSSCs are grouped into the following lithophysical complexes (LC: 1 - coal-bearing silty-clayey-sandy terrigenous, 2 - sandy-silty-clayey terrigenous, 3 - silty-clayey-siliceous, and 4 - sandy-silty-clayey volcanic [Sergeyev, 2006].Tectonic zoning of the sedimentary cover based on structural indicators is carried out with reference to the sediment-thickness map [Sergeyev, 2006], including a significantly revised segment showing the area of the Deryugin basin [Semakin, Kochergin, 2013]. Results of such zoning are represented in the format of a structural-tectonic map (Fig. 3 showing orientations and morphology of the structural elements of the sedimentary cover, the thickness of the sedimentary cover, and amplitudes of relative uplifts and troughs.With reference to the structural-tectonic map (see Fig 3, the structural elements of different orders are grouped by their sizes, spatial positions and orientations and thus comprise tectonic sistems (Fig. 4, structural zones (Fig. 5 that unclude relative uplifts and troughs that are

  4. New approaches in the indirect quantification of thermal rock properties in sedimentary basins: the well-log perspective

    DEFF Research Database (Denmark)

    Fuchs, Sven; Balling, Niels; Förster, Andrea

    capacity in sedimentary rocks derived from data provided by standard geophysical well logs. The approach is based on a data set of synthetic sedimentary rocks (clastic rocks, carbonates and evaporates) composed of mineral assemblages with variable contents of 15 major rock-forming minerals and porosities...... of subsurface rock parameters beyond drill core measurements an approach for the indirect determination of these parameters is developed, for rocks as well a for geological formations. We present new and universally applicable prediction equations for thermal conductivity, thermal diffusivity and specific heat...

  5. Nature and Architecture of the Sedimentary Deposits in the Trench of the Ecuadorian Subduction Margin

    Science.gov (United States)

    Gonzalez, Miguel; Proust, Jean-Noel; Michaud, Francois; Pouderoux, Hugo; Ratzov, Gueorgui

    2016-04-01

    The active margin of Ecuador is characterized by strong tectonic erosion that contributes to the formation of a deep trench filled by a complex suite of sedimentary facies. Gravity flow sedimentation is ubiquitous along the margin and facies range from laterally continuous m-thick mass transport deposits to isolated cm-thick turbidites intercalated with hemipelagite and ash layers. However, the nature and architecture of those deposits remain equivocal. This study presents the interpretation of detailed bathymetry, high-resolution seismic profiles and sediment cores recently acquired along the 600 km-long Ecuadorian margin (ATACAMES campaign onboard the R/V L'Atalante, 2012). The margin comprises three morphological segments: (1) the central segment marked by the subduction of the Carnegie Ridge, which induced a narrow (10-30 km wide) and relatively shallow trench (3100-3700 m deep), a steep and gullied continental slope with no canyon and a 20-60 km wide shelf characterized by active subsidence, (2) the northern segment characterized by a wider (~100 km) and deeper (3800-4000 m) trench, a gentler gullied continental slope and similar shelf settings (10-50 km wide), (3) the southern segment presents a wide (20-60 km) and deep (4000-4700 m) trench, a starved continental slope with well-defined canyon systems and a wide subsiding shelf (50-100 km wide). The sedimentary dynamics along the margin is evaluated by the analysis of 15 sediment cores. High-resolution visual description of the cores, X-Ray imagery and the measurement of petrophysical properties (gamma density, magnetic susceptibility, P-wave velocity) led to the identification of 6 sedimentary facies that characterize 6 sedimentary processes: Turbidite beds (turbidity currents), Hemipelagites (continuous marine sedimentation), Tephras (airfall ash layers consecutive to volcanic eruptions), Debris flow deposits (cohesive debris flows), Megaturbidite/Homogenite (large-scale and/or hybrid gravity flows), Mass

  6. How to find the sedimentary archive of fluvial pollution in a bedrock-confined river reach

    Science.gov (United States)

    Elznicova, Jitka; Matys Grygar, Tomas; Kiss, Timea; Lelkova, Tereza; Balogh, Marton; Sikora, Martin

    2016-04-01

    The Ohre River springs in the Eastern Germany and it is a tributary of the Labe (Elbe) River in Northwest Bohemia. The river received pollution from several sources during the last five centuries. Most of the pollution sources located along the upper and middle reaches, where the depositional and erosional pattern of the river is highly variable. The upper part of the catchment consists of mainly felsic rocks and the river has a broad floodplain. The middle reach and its right-bank tributaries are deeply incised into the Doupovske Hory Mts., which consists of mafic volcanic rocks; whereas the left-bank tributaries are incised into intrusive and metamorphic rocks of the Krusne Hory Mts. (Ore mountains) with several local ore mines (Ag, Pb and U) in particular in around Olovi and Jachymov. Due to the geologic and geomorphologic complexity, deposition of historical sediments in the middle reach has been spatially limited and uneven, and anomalous background concentrations of risk elements are expected. As a consequence, in the middle reach of the Ohre River it is difficult to find a useful sedimentary archive of historical pollution, though it is desired for two main reasons: (1) to decipher the undocumented and poorly described pollution history from the Krusne Hory Mts. and (2) to better understand the retention of pollutants in the transport zones of a confined river system. Based on historical maps we identified a side-bar (35x320 m) in the middle reach of the river near Straz on Ohre and aimed to describe its formation, its recent erosion/deposition history and to evaluate its sedimentary archive value. In the first half of the 19th century it was an island separated from the valley edge by a side channel. Since then there has been no apparent lateral accretion of the bar (its shape has not been changed), but the upstream part of the side channel aggraded by a sediment plug. We evaluated the current bar topography and geomorphology by a detailed field survey

  7. Sedimentary and tectonic environments for uranium mineralization on the Parana Basin, Brazil

    International Nuclear Information System (INIS)

    The Parana Basin is an isolated intracratonic basin in Southeastern South America and is characterized by Paleozoic and Mesozoic clastic sediments and by the location of one of the world's largest lava flows. Uranium mineralization occurs mainly in lower Devonian epineritic feldsphatic sandstones and in fluvio-deltaic channels developed in middle Permian mudstones and sandstones. Stratigraphic and sedimentologic conditions plus tectonic barriers in association with underground water controlled the mineralization. Two uranium deposits with 4250 and 6800 tonnes U of RAR plus EAR were found containing primary (pitchblende and coffinite) and secondary (autunite, sabugalite, uranocircite) minerals. A paleochannel model for the Permo-carboniferous mineralization is quite well established whereas many questions are still open for the confirmation of a model for the Devonian occurrences. Host rock sedimentary environment, ore-forming conditions and source rocks are discussed. (author)

  8. Sedimentary Facies of the West Crocker Formation North Kota Kinabalu-Tuaran Area, Sabah, Malaysia

    Science.gov (United States)

    Mohamed, Azfar; Hadi Abd Rahman, Abdul; Suhaili Ismail, Mohd

    2016-02-01

    Newly outcrops exposed in the West Crocker Formation have led to the detail sedimentolgical analysis of the formation. Eight sedimentary facies have been recognised in which it was divided into three main groups: (1) sand-dominated facies (F1-F2), (2) poorly- sorted unit mixed sand and mud-dominated facies (F3), and (3) mud-dominated facies (F4-F5). These are: F1- graded sandstone (massive to planar laminated), F2-ripple-cross laminated, wavy and convolute lamination sandstone, F3-chaotic beds of mixed sandstone and mudstone blocks and clasts, F4-lenticular bedded of sandstone, and F5-shale. The studies of the formation has come out that it was deposited in a sand-rich submarine fan with specific location located at (1) inner fan channel-levee complex; (2) mid-fan channelised lobes, and (3) outer fan.

  9. Behaviour of Rb and Sr in recent sediments: implication in radiometric dating of sedimentary rocks

    International Nuclear Information System (INIS)

    The purpose of this work is to contribute to the clarification of the conditions for the strontium isotopic homogenization, the relation between Rb and Sr and the dimension and nature of the sedimentary particles, the diagenetic events associate with clay minerals, with sedimentation process and with interstitial fluids. Recent sediments were sampled from different environments: the deltaic region of the Paraiba do Sul River (RJ), the deltaic region of the Acu River (RN), the continental shelf associated with the amazon river mouth (AM), the continental slope and Jacarepagua coastal plain. The samples were analysed by X ray diffraction, scanning electron microscope and chemical and isotopic techniques. Results obtained show that some samples reached uniform strontium isotopic composition (the material will not be isotopically homogeneous) under certain conditions. These conditions include close proximity between samples, clay fraction enriched in expansive minerals such as smectite, and degraded illite associated with deposition preferentially in marine waters. (author). 126 refs., 31 figs., 22 tabs

  10. Sedimentary deposits in Xanthe Terra: Implications for the ancient climate on Mars

    Science.gov (United States)

    Hauber, E.; Gwinner, K.; Kleinhans, M.; Reiss, D.; Di Achille, G.; Ori, G.-G.; Scholten, F.; Marinangeli, L.; Jaumann, R.; Neukum, G.

    2009-07-01

    A variety of sedimentary deposits is observed in Xanthe Terra, Mars, including Gilbert-type deltas, fan deltas dominated by resedimentation processes, and alluvial fans. Sediments were provided through deeply incised valleys, which were probably incised by both runoff and groundwater sapping. Mass balances based on High-Resolution Stereo Camera (HRSC) digital terrain models show that up to ˜30% of the material that was eroded in the valleys is present as deltas or alluvial fan deposits. Stratigraphic relationships and crater counts indicate an age of ˜4.0 to ˜3.8 Ga for the fluvial activity. Hydrologic modeling indicates that the deposits were probably formed in geologically very short time scales. Our results point to episodes of a warmer and wetter climate on early Mars, followed by a long period of significantly reduced erosion rates.

  11. Ore reserve calculations of a sedimentary uranium deposit in Figueira, PR-Brazil

    International Nuclear Information System (INIS)

    The are reserve calculations of a sedimentary uranium deposit in Figueira-PR-Brazil are presented. The evalution of reserves was based on chemical and/or radiometric analisys from boreholes. Geoestatistical methods were used to study the spacial correlation between radiometric and'in situ' uranium content and to calculate the equivalent uranium content without the need for chemical analysis. To this end, a new method was developed based on the regression between accumulated chemical and radiometric grades as determined by increasing thicknesses defined from the maximum peak of the γ-ray logs. Thus, the effect of non-focalization of the probe and of the continuous logging was eliminated. The system of evalution used was two-dimensional using classical Kriging to calculate thicknesses and accumulations determined using distinct cut-off grades. (Author)

  12. Late Oligocene sedimentary environments and provenance abrupt change event in the northern South China Sea

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A significant change in composition was recorded in late Oligocene sediments from the northern South China Sea.This abrupt event coincided with the seafloor spreading axis jump across the Oligocene/Miocene boundary,leading to sedimentation breaks and slumps as well as obvious changes in sediment geochemical composition,and representing the greatest tectonic activity in the South China Sea region since the Oligocene.Through this tectonic event,the sedimentary environment in the Baiyun sag area transformed from a continental shelf in the late Oligocene to a continental slope since the early Miocene,the provenance of the sediments changed from neighboring areas to the hinterland of the South China block,and the sea level rose since the early Miocene in the area.Therefore,this abrupt change event has a profound influence on the evolution of petroleum offshore in the northern South China Sea.

  13. Mineralogy of selected sedimentary interbeds at or near the Idaho National Engineering Laboratory, Idaho

    International Nuclear Information System (INIS)

    The US Geological Survey's (USGS) Project Office at the Idaho National Engineering Laboratory (INEL) analyzed 66 samples from sedimentary interbed cores during a 38-month period beginning in October 1990 to determine bulk and clay mineralogy. These cores had been collected from 19 sites in the Big Lost River Basin, 2 sites in the Birch Creek Basin, and 1 site in the Mud Lake Basin, and were archived at the USGS lithologic core library at the INEL. Mineralogy data indicate that core samples from the Big Lost River Basin have larger mean and median percentages of quartz, total feldspar, and total clay minerals, but smaller mean and median percentages of calcite than the core samples from the Birch Creek Basin. Core samples from the Mud Lake Basin have abundant quartz, total feldspar, calcite, and total clay minerals. Identification of the mineralogy of the Snake River Plain is needed to aid in the study of the hydrology and geochemistry of subsurface waste disposal

  14. Age, sedimentary environments, and other aspects of sandstone and related host rocks for uranium deposits

    International Nuclear Information System (INIS)

    Project II of the Uranium Geology Working Group was assigned to the study of sedimentary basins and sandstone - type uranium deposits. About 40% of the worlds's uranium resources are contained in sandstone-type deposits, which has led to extensive research. The research was carried out mainly by correspondence, and the results reported by 21 geologists from 10 nations are summarized in this report. It investigated five topics dealing with important aspects of the geology of uranium ores in sandstone host formations: age of host rock; partitioning of uranium between continental and marine sediments; latitude limitation on formation of sandstone deposits; effect of rock formation dip on sandstone ores; usefulness of stable isotope and fluid inclusion studies. The results of studies on these subjects form part of a wider programme of the Working Group, whose final results will be presented at the 27th International Geological Congress in Moscow in 1984

  15. Performance of planar and cylindrical carbon electrodes at sedimentary microbial fuel cells.

    Science.gov (United States)

    Sacco, Natalia J; Figuerola, Eva L M; Pataccini, Gabriela; Bonetto, María Celina; Erijman, Leonardo; Cortón, Eduardo

    2012-12-01

    This paper presents data obtained using an indigenous microbial community contained in anaerobic sediments (mud) collected from the shore of the Río de La Plata River (South America). After the sedimentary microbial fuel cells were assembled the evolution of current and power vs. time was studied. Two types of commercially available graphite materials were used as electrodes, which differ mainly in shape and size. In some experiments, an external carbon source (acetate) increased the power generation rate. The maximum power density observed in the aforementioned condition was 19.57 ± 0.35 and 8.72 ± 1.39 mW/m(2) using rod and graphite disk electrodes, respectively. The better performance of the rod electrodes can be explained, at least in part, by an enhanced rate of mass transport by radial diffusion. DGGE fingerprints were used to study the electrogenic community growing over the electrodes. PMID:23142927

  16. Norway and adjacent sedimentary basins during Cenozoic times - sediment fluxes, accumulation rates and mass balance

    DEFF Research Database (Denmark)

    Gołędowski, Bartosz; Nielsen, S.B.; Clausen, O.R.

    2011-01-01

    stable Eocene epoch. Furthermore, histograms of depositional rates in the study area show a common feature with global patterns, that is a few-fold increase in sediment production during last 3-4 million years. This correlates well with the climate cooling, increased frequency of climate change and...... use offshore data from adjacent sedimentary basins (the North Sea and the Norwegian shelf) to calculate the amount of erosion. We have used a broad dataset of seismic 2D lines to map depositional units and a well dataset for the stratigraphic control and the velocity distribution in the sediments. We...... have therefore obtained accumulation rates in meters per million years for 5 depositional units in three areas - Southern North Sea, Central and Northern North Sea and the Norwegian shelf. Furthermore, taking into account the decay of porosity in sediments with burial depth, we have estimated the...

  17. Simulation of sedimentary rock deformation: Lab-scale model calibration and parameterization

    Science.gov (United States)

    Boutt, David F.; McPherson, Brian J. O. L.

    2002-02-01

    Understanding the mechanical behavior of rock is critical for researchers and decision-makers in fields from petroleum recovery to hazardous waste disposal. Traditional continuum-based numerical models are hampered by inadequate constitutive relationships governing fracture initiation and growth. To overcome limits associated with continuum models we employed a discrete model based on the fundamental laws of contact physics to calibrate triaxial tests. Results from simulations of triaxial compression tests on a suite of sedimentary rocks indicate that the basic physics of rock behavior are clearly captured. Evidence for this conclusion lie in the fact that one set of model parameters describes rock behavior at many confining pressures. The use of both inelastic and elastic parameters for comparison yields insight concerning the uniqueness of these models. These tests will facilitate development and calibration of larger scale discrete element models, which may be applied to a wide range of geological problems.

  18. The influence of facies heterogeneity on the doublet performance in low-enthalpy geothermal sedimentary reservoirs

    DEFF Research Database (Denmark)

    Crooijmans, R. A.; Willems, C. J L; Nick, Hamid;

    2016-01-01

    A three-dimensional model is used to study the influence of facies heterogeneity on energy production under different operational conditions of low-enthalpy geothermal doublet systems. Process-based facies modelling is utilised for the Nieuwerkerk sedimentary formation in the West Netherlands Basin...... and the energy recovery rate for different discharge rates and the production temperature (Tmin) above which the doublet is working. With respect to the results, we propose a design model to estimate the life time and energy recovery rate of the geothermal doublet. The life time is estimated as a function of N...... errors in predicting the life time of low-enthalpy geothermal systems for N/G values below 70%....

  19. Understanding the subsurface thermal structure of deep sedimentary basins in Denmark - measurements and modelling results

    DEFF Research Database (Denmark)

    Balling, N.; Poulsen, Søren Erbs; Bording, Thue Sylvester;

    2015-01-01

    Most of the Danish area is characterized by deep sedimentary basins with a great potential for exploitation of geothermal energy. Geothermal reservoirs are present at various depths and temperatures. Currently, three geothermal plants are operating producing warm water for district heating purposes...... of different conductivity. Mean geothermal gradients from surface to depths of 1000 to 3000 m are generally between 20 and 35 °C/km. The subsurface thermal structure is clearly dominated by conduction. Advection by groundwater migration is generally insignificant. Heat flow increases significantly with depth...... due to perturbation from long-term palaeoclimatic surface temperature variations. Examples of modelled temperature distribution for selected geothermal reservoir are shown. In the Gassum Formation, which is present in most of the Danish area, temperatures are largely between 35 and 90 °C for depths...

  20. The Holocene sedimentary history of the Kangerlussuaq Fjord-valley fill, West Greenland

    DEFF Research Database (Denmark)

    Storms, Joep E.A.; de Winter, Ilja L.; Overeem, Irina;

    2012-01-01

    valleys. Based on published and new land- and sea-based geophysical data, radiocarbon dates and geological observations we have characterized the infill and reconstructed the sedimentation history during the Holocene. Based on a revised sea level curve and data presented in this paper we defined three......West Greenland has been intensively studied to reconstruct and better understand past relative sea level changes and deglacial history. This study extends these efforts by linking sea level and deglacial history to the sedimentary infill successions of Kangerlussuaq Fjord and associated landward...... depositional phases. Phase I (>7000 yr BP) is represented by dominant glaciomarine deposition associated with a tide-water glacier system. As the Greenland Ice Sheet (GIS) continued to retreat it became land based. During phase II (7000-1500 yr BP) two separate depocenters formed. Keglen delta depocenter arose...

  1. Ferroan dolomite cement in Cambrian sandstones: burial history and hydrocarbon generation of the Baltic sedimentary basin

    DEFF Research Database (Denmark)

    Sliaupa, S.; Cyziene, J.; Molenaar, Nicolaas;

    2008-01-01

    The conditions and timing of carbonate cementation in Cambrian sandstones of the Baltic sedimentary basin were determined by oxygen and carbon stable isotope and chemical data in combination with optical and cathodoluminescence petrographic studies. Studied samples represent a range in present...... burial depth from 340 to 2150 m. The carbonate cement is dominantly ferroan dolomite that occurs as dispersed patches of poikilotopic crystals. Temperatures of dolomite precipitation, based on delta O-18 values, range from 27 degrees C in the shallow buried to 95 degrees C in the deep buried sandstones....... The burial history modelling points to development of most of the dolomite cement during rapid Silurian-Devonian subsidence and Carboniferous-early Permian uplift. A wide range of precipitation temperatures indicate that temperature was not a major factor in triggering the carbonate cementation. Dolomite...

  2. A study of radionuclide transfer between invertebrates and their marine sedimentary environment

    International Nuclear Information System (INIS)

    Exchanges between sediment and marine organisms were studied in some benthic marine invertebrates, especially Arenicola marina L. (an Annelid). Experiments were carried out on the transfer of 60Co, 137Cs and accessorily 59Fe and 144Ce. Water was the chief vector for benthic marine invertebrates. These invertebrates seemed to act mainly in sedimentary areas on the redistribution of adsorbed radionuclides within the sediment. Radioactive contamination of the invertebrates was affected by various physiological or ecological factors. Benthic marine invertebrates were then studied as links in food chains. The transfer of 60Co was studied in three food chains or fractions of food chains. The procedure allowed interesting observations from the health protection point of view and more fundamental investigations on cobalt metabolism (regulation, excretion) in a mollusc, a crustacea and a teleost

  3. The influence of facies heterogeneity on the doublet performance in low-enthalpy geothermal sedimentary reservoirs

    DEFF Research Database (Denmark)

    Crooijmans, R. A.; Willems, C. J L; Nick, Hamid;

    2016-01-01

    A three-dimensional model is used to study the influence of facies heterogeneity on energy production under different operational conditions of low-enthalpy geothermal doublet systems. Process-based facies modelling is utilised for the Nieuwerkerk sedimentary formation in the West Netherlands Basin...... life time and the energy recovery rate for different discharge rates and the production temperature (Tmin) above which the doublet is working. With respect to the results, we propose a design model to estimate the life time and energy recovery rate of the geothermal doublet. The life time is estimated...... lead to significant errors in predicting the life time of low-enthalpy geothermal systems for N/G values below 70%....

  4. Tectonic and climatic control on geomorphological and sedimentary evolution of the Mercure basin, southern Apennines, Italy

    Science.gov (United States)

    Robustelli, Gaetano; Ermolli, Elda Russo; Petrosino, Paola; Jicha, Brian; Sardella, Raffaele; Donato, Paola

    2014-06-01

    The morpho-tectonic and sedimentary evolution of the Mercure intramontane basin (Calabria-Lucania boundary, southern Apennines) has been assessed through facies analysis, morphostratigraphy and geomorphological correlation with adjacent areas. The Mercure basin, one of the most active seismogenic zones of the southern Apennines, is a favorable area for reconstructing the main stages of landscape evolution of the axial zone because of its capability to record changes in base level during the Quaternary. In addition, the presence of both erosional and depositional Palaeosurfaces is a useful marker for reconstructing tectonic and morphogenetic events, and hence to detect the role played by tectonics and climate in its genesis, evolution and extinction. The present study identifies the key role of tectonics and denudation, combined with high-frequency floods, as mechanisms controlling alluvial sedimentation in the study area. During endorheic conditions, denudational processes driven by pulses of extensional deformation of the basin margin caused strong alluvial inputs that resulted in the development of alluvial fans. Alluvial facies are mainly characterized by turbulent, subaerial, hyperconcentrated flood flows deposited during the glacial, semi-arid conditions of MIS 14. The retrogradational stacking pattern of the alluvial system indicates decreasing rates of tectonic activity along with declining river gradients. The Mercure coalescing alluvial fans were inundated by lake transgression during MIS 13 in response to (i) abrupt tectonic subsidence at the basin margins and (ii) large decrease of coarse sediment supply due to the interplay among climate, tectonics and catchment size changes. In this regard, it is suggested that tectonic control on the drainage network along with climate and long-term slope evolution may have caused marked pulses in sediment supply, thus influencing the arrangement of facies associations in the sedimentary succession. In addition, the

  5. Investigating the elastic properties of sedimentary basins on different spatial scales

    Science.gov (United States)

    Krause, Martin; Methe, Pascal; Goepel, Andreas; Bleibinhaus, Florian; Kukowski, Nina

    2014-05-01

    The study of subsurface fluid motion is important e.g. for understanding ground water motion or processes of compaction, diagenesis, and hydrocarbon migration in sedimentary basins. The multidisciplinary project INFLUINS (INtegrated FLUid dynamics IN Sedimentary basins) aims for investigating the coupled dynamics of near surface and deep fluid patterns and material transport in the Thuringian Basin (Germany). In order to gain information on how fluid flow processes depend on basin architecture, and therefore its physical properties, we first image the subsurface structure of the Thuringian Basin using seismic methods. Then, relations between hydraulic and elastic material parameters are required to also image the hydraulic structure of the basin's subsurface. As hydraulic properties often significantly vary with spatial scales, such a study requires a combination of small- to large-scale seismic data sets. In the framework of INFLUINS a variety of seismic data sets aiming for different subsurface parameters and spatial scales have been acquired. Basin scale seismic data sets are available from a set of 2D reflection seismic profiles as well as 2.5D and 3D seismic travel time tomography. Laboratory scale seismic data characterizing the basin's rocks is provided by ultrasound experiments on drill cores from the Thuringian Basin. Deep drilling conducted in the framework of INFLUINS in 2013 provides further useful data sets for our purpose: we acquired core material for laboratory ultrasound analysis and sonic-log data. As the drill site is located at the cross point of two seismic reflection profiles and also within the array of seismic stations we used for the 3D travel time tomography, it serves a direct transfer of elastic properties between different scales.

  6. Sedimentary Parameters Controlling Occurrence and Preservation of Microbial Mats in Siliciclastic Depositional Systems

    Science.gov (United States)

    Noffke, Nora; Knoll, Andrew H.

    2001-01-01

    Shallow-marine, siliciclastic depositional systems are governed by physical sedimentary processes. Mineral precipitation or penecontemporaneous cementation play minor roles. Today, coastal siliciclastic environments may be colonized by a variety of epibenthic, mat-forming cyanobacteria. Studies on microbial mats showed that they are not randomly distributed in modern tidal environments. Distribution and abundancy is mainly function of a particular sedimentary facies. Fine-grained sands composed of "clear" (translucent) quartz particles constitute preferred substrates for cyanobacteria. Mat-builders also favor sites characterized by moderate hydrodynamic flow regimes, which permit biomass enrichment and construction of mat fabrics without lethal burial of mat populations by fine sediments. A comparable facies relationship can be observed in ancient siliciclastic shelf successions from the terminal Neoproterozoic Nama Group, Namibia. Wrinkle structures that record microbial mats are present but sparsely distributed in mid- to inner shelf sandstones of the Nudaus Formation. The sporadic distribution of these structures reflects both the narrow ecological window that governs mat development and the distinctive taphonomic conditions needed to preserve the structures. These observations caution that statements about changing mat abundance across the Proterozoic-Cambrian boundary must be firmly rooted in paleoenvironmental and taphonomic analysis. Understanding the factors that influence the formation and preservation of microbial structures in siliciclastic regimes can facilitate exploration for biological signatures in Earth's oldest rocks. Moreover, insofar as these structures can be preserved on bedding surfaces and are not easily mimicked by physical processes, they constitute a set of biological markers that can be searched for on Mars by remotely controlled rovers.

  7. Tracing contaminant pathways in sandy heterogeneous glaciofluvial sediments using a sedimentary depositional model

    International Nuclear Information System (INIS)

    Heterogeneous sedimentary deposits present complications for tracking contaminant movement by causing a complex advective flow field. Connected areas of high conductivity produce so-called fast paths that control movement of solutes. Identifying potential fast paths and describing the variation in hydraulic properties was attempted through simulating the deposition of a glaciofluvial deposit (outwash). Glaciofluvial deposits usually consist of several depositional facies, each of which has different physical characteristics, depositional structures and hydraulic properties. Therefore, it is unlikely that the property of stationarity (a constant mean hydraulic conductivity and a mono-modal probability distribution) holds for an entire glaciofluvial sequence. However, the process of dividing an outwash sequence into geologic facies presumably identifies units of material with similar physical characteristics. It is proposed that patterns of geologic facies determined by field observation can be quantified by mathematical simulation of sediment deposition. Subsequently, the simulated sediment distributions can be used to define the distribution of hydrogeologic parameters and locate possible fast paths. To test this hypothesis, a hypothetical glacial outwash deposit based on geologic facies descriptions contained in the literature was simulated using a sedimentary depositional model, SEDSIM, to produce a three-dimensional description of sediment grain size distributions. Grain size distributions were then used to estimate the spatial distribution of hydraulic conductivity. Subsequently a finite-difference flow model and linked particle tracking algorithm were used to trace conservative transport pathways. This represents a first step in describing the spatial heterogeneity of hydrogeologic characteristics for glaciofluvial and other braided stream environments. (Author) (39 refs., 7 figs.)

  8. Reconstructing Past Depositional and Diagenetic Processes through Quantitative Stratigraphic Analysis of the Martian Sedimentary Rock Record

    Science.gov (United States)

    Stack, Kathryn M.

    High-resolution orbital and in situ observations acquired of the Martian surface during the past two decades provide the opportunity to study the rock record of Mars at an unprecedented level of detail. This dissertation consists of four studies whose common goal is to establish new standards for the quantitative analysis of visible and near-infrared data from the surface of Mars. Through the compilation of global image inventories, application of stratigraphic and sedimentologic statistical methods, and use of laboratory analogs, this dissertation provides insight into the history of past depositional and diagenetic processes on Mars. The first study presents a global inventory of stratified deposits observed in images from the High Resolution Image Science Experiment (HiRISE) camera on-board the Mars Reconnaissance Orbiter. This work uses the widespread coverage of high-resolution orbital images to make global-scale observations about the processes controlling sediment transport and deposition on Mars. The next chapter presents a study of bed thickness distributions in Martian sedimentary deposits, showing how statistical methods can be used to establish quantitative criteria for evaluating the depositional history of stratified deposits observed in orbital images. The third study tests the ability of spectral mixing models to obtain quantitative mineral abundances from near-infrared reflectance spectra of clay and sulfate mixtures in the laboratory for application to the analysis of orbital spectra of sedimentary deposits on Mars. The final study employs a statistical analysis of the size, shape, and distribution of nodules observed by the Mars Science Laboratory Curiosity rover team in the Sheepbed mudstone at Yellowknife Bay in Gale crater. This analysis is used to evaluate hypotheses for nodule formation and to gain insight into the diagenetic history of an ancient habitable environment on Mars.

  9. Dolomitization and sedimentary cyclicity of the Ordovician, Silurian, and Devonian rocks in South Estonia

    Directory of Open Access Journals (Sweden)

    Kallaste, Toivo

    2006-03-01

    Full Text Available The distribution and composition of dolomitized rocks and stoichiometry of dolomite in southern Estonia in the Ordovician, Silurian, and Devonian were studied on the background of the facies, sedimentary cyclicity (nine shallowing-up cycles, and evolution of the palaeobasins. The composition of rocks and lattice parameters of dolomite were investigated using the X-ray diffraction, X-ray fluorescence, titration and gravimetric analyses, and porosity measurements. The formation of dolostones is directly determined by the cyclic evolution of palaeobasins. Dolomitized rocks belong to the shallow-water inner shelf or tidal/lagoonal facies belt of regressive phases of sedimentary cycles. Sediments of the deep shelf/transitional environment and transgressive phases are not dolomitized. The most stoichiometric is secondary replacive dolomite of Silurian and upper Ordovician dolostones, formed during the early diagenesis of normal-marine (saline shallow-shelf calcitic sediments. The content of insoluble residue does not affect the stoichiometry. The changes in lattice parameters are induced by the Ca/Mg ratio in the dolomite lattice. The dolomite of the dolostones contacting limestone or containing calcite has an expanded lattice. The primary (syngenetic dolostone of the lagoonal or tidal flat belt has also an expanded lattice. No dolomitizing effect of the waters of the Devonian palaeobasin on the underlying rocks was revealed. The whole data set of the studied dolostones is consistent with the marine water environment in the palaeobasin at the corresponding time and shows no sign of the inflow of external fluids. It suggests that the microbial model of dolomite formation may characterize the Ordovician, Silurian, and Devonian in southern Estonia. The occurrence of dolostones between undolomitized rocks limits the time of dolomitization to the early diagenetic stage.

  10. Sedimentary record of Earthquakes and Tsunamis in the Central Mediterranean Sea

    Science.gov (United States)

    Polonia, A.; Romano, S.; Vaiani, S. C.; Gasparotto, G.; Gasperini, L.; Nelson, C. H.

    2014-12-01

    The Ionian Sea is a landlocked basin where convergence between Africa and Eurasia produced the emplacement of two opposite verging subduction/rollback systems (i.e. the Calabrian and the Hellenic Arcs). It is one of the most seismically active regions in the Mediterranean Sea and has been struck repeatedly by destructive historical earthquakes, often associated with tsunamis. Slab tearing in a pre-collisional setting is reflected in dynamic topography with high uplift rates of the coastal mountain belts, accompanied with a great sediment discharge to the continental margins. This increases the susceptibility to mass failures implying a strong interplay between active tectonics, seismic shaking, mass flows and tsunami generation.We investigated the effects of historic earthquakes on abyssal marine sedimentation through the analysis of the turbidite record in tectonically controlled basins. Holocene resedimented units in the deep Ionian Sea represent more than 90% of the total thickness of the sedimentary record. We dated the most recent turbidite sequences using different radiometric methods and the results suggest that turbidite emplacement was triggered by major historic earthquakes and tsunamis recorded in the region (i.e. AD 365 Crete and AD 1169, 1693 and 1908 Italian earthquakes).Textural, micropaleontological, geochemical and mineralogical signatures reveal that turbidite beds are stacked sandy units, which have different compositions suggesting coeval multiple failures. They are characterized by organic-rich sandy layers, containing a mixture of lithic clasts, plant fragments and displaced benthic foraminifera derived from several sources and bathymetric ranges. Structure and composition of each turbidite unit, combined with geochemical and isotopic analysis on organic carbon, are being refined to unravel the relative contribution of seismic shaking and tsunami wave loading on mass flow processes generation.Turbidites may be considered as the sedimentary

  11. Magnetostratigraphy of the Middle-Upper Jurassic sedimentary sequences at Yanshiping, Qiangtang Basin, China

    Science.gov (United States)

    Song, Chunhui; Zeng, Yongyao; Yan, Maodu; Wu, Song; Fang, Xiaomin; Bao, Jing; Zan, Jinbo; Liu, Xifang

    2016-05-01

    A series of important geological events occurred in the Tibetan Plateau area during the Jurassic, such as the collision of the Lhasa and Qiangtang Terranes, the closure of the Meso-Tethyan Ocean, the opening of the Neo-Tethyan Ocean and the cessation of the mega-monsoon. The ˜3,000-m-thick Jurassic sedimentary sequence in the Qiangtang Basin on the central Tibetan Plateau, which is called the Yanshiping Group, recorded these geological events. However, the chronology of the sequence is surprisingly poorly constrained. Here, we perform a detailed palaeomagnetic analysis on the ˜1,060-m-thick middle and upper portions of the Yanshiping Group (the Xiali and Suowa Formations) in the Yanshiping section of the eastern Qiangtang Basin. Three bivalve zones at stratigraphic intervals of ˜40-140 m, 640-800 m and 940-1040 m are identified, which yield a Bathonian-Callovian age for the Lower Xiali Fm., a Callovian-Oxfordian age for the Lower Suowa Fm., and an Oxfordian-Kimmeridgian age for the Upper Suowa Fm. A total of 544 oriented palaeomagnetic samples were collected from the section. By combining thermal and alternating field demagnetizations, clear characteristic remanent magnetization (ChRM) directions are isolated for most of the samples. The robust ChRM directions pass fold and reversals tests, which support the primary nature of the ChRMs and yield a palaeopole at 76.8°N/297.2°E (dp = 2.2°, dm = 3.7°). A total of 27 normal and 26 reversed polarity zones were successfully recorded in the section. Combined with fossil age constraints, results suggest that the section is plausibly composed of a Callovian-Early Kimmeridgian age sedimentary sequence.

  12. Short-term natural gas deliverability from the Western Canada Sedimentary Basin 2000-2002

    International Nuclear Information System (INIS)

    Factors which affect natural gas supply in the short term are discussed and a forecast for deliverability to the year 2002 is provided as part of the ongoing effort by the National Energy Board to provide analyses of the major energy commodities on either an individual or integrated commodity basis. The objective of these energy market assessment reports is to advance the understanding of the short-term supply situation by reviewing recent trends in the production characteristics of the Western Canada Sedimentary Basin and to update previous reports on short-term deliverability. This report focuses on a review of producing characteristics of natural gas wells from 1990 to 1999. These producing characteristics are then combined with forecasts of drilling activity in order to generate a forecast of natural gas deliverability from 2000 to 2002. Two key trends were identified during the review process. First, recently drilled wells were found to produce at lower rates than wells drilled more than five years ago; second, production from these wells were shown to decline more quickly than production from older wells. Based on these observations, it was concluded that future wells will be generally less productive than wells which were drilled a few years ago, therefore, more wells will have to be drilled to offset production declines from existing gas wells if deliverability is to be maintained or increased. The National Energy Board expects 8,100 wells to be drilled in 2000, followed by 8,700 natural gas wells in 2001 and 8,900 in 2002. A shift in drilling activity to more prolific areas located in the western and northern parts of the Western Canada Sedimentary Basin is also expected. Based on these estimates of expected drilling activity, total deliverability is projected to increase from 465 million cubic feet per day in 1999 to 495 million cubic feet in 2002. Specialized statistics and forecast data are provided in the appendices. 3 tabs., 11 figs., 6 appendices

  13. Basin-floor fans in the North Sea: Sequence stratigraphic models vs. sedimentary facies

    Energy Technology Data Exchange (ETDEWEB)

    Shanmugam, G.; Bloch, R.B. [Mobil Research and Development Corp., Dallas, TX (United States); Mitchell, S.M. [Mobil Exploration and Producing US, Inc., Dallas, TX (United States); Beamish, G.W.J.; Shields, K.E. [Mobil North Sea Ltd., London (United Kingdom); Hodgkinson, R.J.; Straume, T.; Syvertsen, S.E. [Mobil Exploration Norway, Inc., Stavanger (Norway); Damuth, J.E. [Univ. of Texas, Arlington, TX (United States)

    1995-04-01

    Examination of nearly 12,000 feet (3658m) of conventional core from Paleogene and Cretaceous deep-water sandstone reservoirs cored in 50 wells in 10 different areas or fields in the North Sea and adjacent regions reveals that these reservoirs are predominantly composed of mass-transport deposits, mainly sandy slumps and sandy debris flows. Sedimentary features indicating slump and debris-flow origin include sand units with sharp upper contacts; slump folds; discordant, steeply dipping layers (up to 60{degrees}); glide planes; shear zones; brecciated clasts; clastic injections; floating mudstone clasts; planar clast fabric; inverse grading of clasts; and moderate-to-high matrix content (5-30%). This model predicts that basin-floor fans are predominantly composed of sand-rich turbidites with laterally extensive, sheetlike geometries. However, calibration of sedimentary facies in our long (400-700 feet) cores with seismic and wire-line-log signatures through several of these basin-floor fans (including the Gryphon-Forth, Frigg, and Faeroe areas) shows that these features are actually composed almost exclusively of mass-transport deposits consisting mainly of slumps and debris flows. Distinguishing deposits of mass-transport processes, such as debris flows, from those of turbidity currents has important implications for predicting reservoir geometry. Debris flows, which have plastic flow rheology, can form discontinuous, disconnected sand bodies that are harder to delineate and less economical to develop than deposits of fluidal turbidity currents, which potentially produce more laterally continuous, interconnected sand bodies. Process sedimentological interpretation of conventional core is commonly critical for determining the true origin and distribution of reservoir sands.

  14. A Global Record of Surface Earth Oxygenation from Sedimentary V/Sc

    Science.gov (United States)

    Keller, C. B.; Schoene, B.; Johnston, D. T.

    2015-12-01

    One of the simplest methods to investigate changes in oxidation potential in geologic environments is to examine a pair of otherwise similar elements with dramatically different redox chemistry. The first-row transition metals Sc and V represent one such pair, with generally similar mass, radius, and ionization energies up to the trivalent redox state. However, as a d3 transition metal, Sc is limited to a maximum oxidation state of 3+, while d5 vanadium may be further oxidized to form tetravalent and pentavalent ions. Due to the greater incompatibility of pentavalent (relative to trivalent) metal cations in silicate melts, V/Sc ratio has been applied to the silicate rock record as a tracer of magma redox - indicating roughly constant mantle oxygen fugacity over Earth history1,2. As a result, the solid earth represents a boundary condition with constant V/Sc observed over geologic time1. However, oxidation state also affects the weathering, solubility, and coordination behaviour of V and Sc, resulting in a potential redox signal in the sedimentary V/Sc record. We apply the weighted bootstrap resampling approach of [2] to a geochemical dataset of ~87,000 sedimentary whole-rock analyses from the EarthChem portal3. The resulting trends reveal a 4 Gyr record of V/Sc redox chemistry, with the great oxidation event represented as an upward step ca. 2.5 Ga, and Phanerozoic variation suggestive of low oxygen in the early Paleozoic, increasing to twin maxima circa 270 Ma and 130 Ma, remarkably similar to that predicted by the COPSE model4, and broadly congruent with the Phanerozoic biochar record5. Li, Z.-X. A. & Lee, C.-T. A. EPSL 228, 483-493 (2004). Keller, C. B. & Schoene, B. Nature 485, 490-493 (2012). EarthChem Bergman, N. M. Am. J. Science 304, 397-437 (2004). Glasspool, I. J. & Scott, A. C. Nat. Geosci. 3, 627-630 (2010).

  15. Integrated Provenance Studies in Northwestern South America, Linking Tectonic and Sedimentary Processes

    Science.gov (United States)

    Montes, C.; Cardona, A.; Ramirez, V. O.; Bayona, G.; Ayala, C.; Valencia, V.

    2009-12-01

    Post-collisional late Eocene to Oligocene extensional basins (Plato-San Jorge basin in Colombia) and syn-collisional basins to the east contain the record of drainages and source areas as a former passive margin obliquely collided with the Caribbean deformation front. A 2 to 8 km thick, shallowing-upward and almost entirely fine-grained, upper Eocene and younger sedimentary sequence contains the record of post-collisional paleogeography behind the advancing deformation front. Sedimentation in the syn-collisional margin is fragmentary along the northern margins of Colombia and Venezuela in the Guajira province. An integrated provenance approach is being undertaken with detrital zircon geochronology, whole rock geochemistry, heavy mineral analysis and tectonic modeling. Source areas contain distinctive assemblages that should be diagnostic and include cratonic contributions with Grenville and older provinces, Andean contributions with Mesozoic-age signatures and Caribbean contributions with latest Cretaceous and Paleogene contributions. The complex Paleogene tectonic interactions along the northwestern South American margin include the simultaneous opening of basins (Plato-San Jorge basin in Colombia), micro-block rotation (Santa Marta massif), shortening and mountain building (Perija range) and oblique accretionary wedges along the margin (Sinu-San Jacinto deformed belts). Rivers draining the interior of South America to the north would have been deflected by this Paleogene configuration, and local drainages would have similarly developed in response to changing depocenters. Distinctive signatures should have developed in the sedimentary sequence as the sources dynamically changed from cratonic (Grenville and older cratonic) to Andean (Mesozoic continental crust and reworked) to Caribbean (volcanic arcs and collision zones).

  16. A sedimentary model for early Palaeozoic fluvial fans, Alderney Sandstone Formation (Channel Islands, UK)

    Science.gov (United States)

    Ielpi, Alessandro; Ghinassi, Massimiliano

    2016-08-01

    Fluvial fans in the rock record are inferred based on critical criteria such as: downstream grain-size fining; evidence for drainage fractionation along bifurcating channels; increasing fluvial-aeolian interaction in the basinward direction; and radial palaeoflow dispersion. Since pre-vegetation fluvial rocks often lack heterolithic alluvium and channelisation at the outcrop scale, the recognition of pre-Silurian fluvial fans has, so far, not been straightforward. This research proposes a sedimentary model for the Alderney Sandstone Formation of Channel Islands (UK), so far considered as a fine record of early Palaeozoic axial-fluvial sedimentation. Here, outcrop-based and remote-sensing analysis of the formation's type-section reveal the interaction of fluvial and aeolian processes, expressed by the alternation of: compound fluvial bars enclosing macroform surfaces, related to phases of perennial discharge; fluvial sandsheets containing antidunal forms and soft-sediment deformations, related to seasonal (i.e. flashy) discharge; and aeolian bedforms overlying thin stream-flow deposits. An up-section increase in aeolian deposits is accompanied by the shrinking of fluvial bars and minor-channel cuts, suggesting that drainage was fractioned along smaller channels terminating into marginal aeolian environments. Together with a propensity towards more dispersed values of fluvial cross-set thickness up-section (again due to discharge fractionation along intermittently active channels), these features depict an aeolian-influenced fluvial fan. This work discusses a set of criteria for the identification of fluvial fans in pre-vegetation environments. In doing so, it also explores possible parallels to modern environments, and underscores the potential of integrated outcrop and remotely sensed observations on ancient fluvial rocks and modern sedimentary realms.

  17. Reconstructing Flow Patterns from Tsunami Deposits with No Visible Sedimentary Structure

    Science.gov (United States)

    Kain, C. L.; Chague-Goff, C.; Goff, J. R.; Wassmer, P.; Gomez, C. A.; Hart, D. E.

    2014-12-01

    High energy coastal events, such as tsunamis, commonly leave sediment deposits in the landscape that may be preserved in the geological record. A set of anomalous sand and silt layers intercalated between soil units was identified alongside an estuary in Okains Bay, Banks Peninsula, New Zealand. Okains Bay, comprised of a coastal plain of Holocene progradational dune ridges, was flooded by tsunamis in 1868 and 1960. Previous research has assessed the relationship between tsunami flow patterns and sediment deposits for recent events, and we aim to extend this application to older deposits where flow patterns were not recorded and sedimentary structures are not visually apparent. A multi-proxy approach was used to investigate the sediment deposits at twelve sites along a 2 km length of the estuary margin and map inundation patterns. Measurements of Magnetic Fabric (MF: Anisotropy of Magnetic Susceptibility) were used to determine the flow direction during deposition, alongside stratigraphy and particle size analyses to assess wave energy. Flow direction results were overlaid on a digital elevation model of the study site to interpret flow patterns. Deposits became thinner and particle size decreased with distance from the coast, indicating waning flow energy with distance inland. MF results indicate that inundation occurred via the estuary channel, with primary flow directions oriented perpendicular or sub-perpendicular to the channel at each site. On a smaller scale, results showed evidence of current reversal at some sites, with flow directed alternately away from and towards the estuary channel. This is consistent with uprush and backwash patterns observed in tsunami wave sequences. Topographic control of flow patterns is also evident from the data. This research demonstrates a method for investigating older, structurally-degraded deposits and has implications for the reconstruction of paleotsunami inundation from their sedimentary deposits.

  18. Sedimentary Response of AN Ephemeral Lake during Deglacial and Holocene Climate Evolution, Swan Lake, Southeast Idaho.

    Science.gov (United States)

    Rosario, J. J.; Miller, D. M.; Wahl, D.; Anderson, L.; Tripati, A.; Presnetsova, L.; Oviatt, C. G.; McGeehin, J. P.; Bright, J. E.

    2014-12-01

    Perennial water systems are important ecological resources in the arid western US and provide many ecosystem services. Lakes can record fluctuations in climate (such as temperature and effective moisture) and can offer insight into regional variations in climate patterns. We studied a 7.65-m core from Swan Lake, which is a small lake and wetland complex that seasonally overflows, to examine small scale climate changes in its continuous sedimentary record. Our core is similar to that studied by Bright (1966), which exhibits two primary sedimentary facies, mud and peat, with a time span of 13.5 cal ka. The methodology includes radiocarbon dating, particle size analyses, sediment mineralogy, stable isotopes and clumped isotopes on calcium carbonate. Mud in the lower half of the core is primarily composed of clay and silt-size quartz-feldspar, but it transitions to calcium carbonate mud. Clays change from 660 to 585 cm and 350 to 220 cm in the core with an increase in kaolinite and illite upward. Ostracods in the carbonate muds are fairly uniform, indicating a mixture of wetland and lake environments from the last 5.8 ka. Similarly, summer temperatures obtained using Δ47 measurements show fluctuations in the range of 18.1 to 23.4 oC with carbonate muds generally corresponding to lower temperatures and peats to higher temperatures. We interpret muds as open water, shallow lake conditions and peats as wetlands across the floor of the ephemeral lake. If our interpretations are correct, the time from onset of the Younger Dryas to the end of the early Holocene was effectively dry, with low groundwater discharge. Similar events occurred from 4.7 to 1.0 ka and briefly at ~400 cal yr BP. Warmer climate may lead to effective moisture increase in this part of the eastern Great Basin.

  19. Sedimentary basin analysis and petroleum potential of the Cretaceous and Tertiary strata in Korea.

    Energy Technology Data Exchange (ETDEWEB)

    Son, Jin-Dam; Kwak, Young-Hoon; Bong, Pil-Yoon [Korea Institute of Geology Mining and Materials, Taejon (KR)] (and others)

    1999-12-01

    Since 1992 sedimentary basin analysis to assess petroleum potential of the Cretaceous and Tertiary strata in the Korean onshore and continental shelf have been carried out. The Cretaceous non-marine strata mainly occupy the Gyeongsang Basin in southeastern part of the Korean Peninsula and small basins such as Haenam and Gyeokpo depressions in western coastal areas. The Tertiary strata are mostly distributed in Domi, Cheju, Socotra subbasins, and Okinawa Trough in the South Continental Shelf, and Kunsan and Heuksan basins in the West. The basin evolution and petroleum potential for each basins are characterized as follow. The Cretaceous Gyeongsang sediments were deposited in three subbasins including Milyang, Euisung and Yongyang subbasins. The black shales in Nakdong and Jinju formations are interpreted to contain abundant organic matter during the deposition, thermal maturity reaching up to the zone of dry gas formation. Because porosity and permeability are too low, the sandstones can act as a tight gas reservoir rather than conventional oil and gas reservoir. The latest Cretaceous strata of Haenam and Kyeokpo depressions in western coastal area are correlated into the Yuchon Volcanic Group of the Gyeongsang Basin. Petroleum potential of the Early Cretaceous basin in the West Continental Shelf could be relatively high in terms of sedimentary basin filled with thick lacustrine sediments. The Kunsan basin in the West Continental Shelf originated in the Early Cretaceous time expanded during the Paleocene time followed by regional erosion at the end of Paleocene on which Neogene sediment have been accumulated. The Paleocene-Eocene sublacustrine shales may play an major role as a source and cap rocks. South Continental Shelf Basin is subdivided by Cheju subbasin in the center, Socotra Subbasin to the west, Domi Subbasin to the northeast and Okinawa Trough to the East. The potential hydrocarbon traps associated with anticline, titled fault blocks, fault, unconformity

  20. Seedling establishment in a dynamic sedimentary environment: a conceptual framework using mangroves.

    Science.gov (United States)

    Balke, Thorsten; Webb, Edward L; van den Elzen, Eva; Galli, Demis; Herman, Peter M J; Bouma, Tjeerd J

    2013-06-01

    1. Vegetated biogeomorphic systems (e.g. mangroves, salt marshes, dunes, riparian vegetation) have been intensively studied for the impact of the biota on sediment transport processes and the resulting self-organization of such landscapes. However, there is a lack of understanding of physical disturbance mechanisms that limit primary colonization in active sedimentary environments. 2. This study elucidates the effect of sediment disturbance during the seedling stage of pioneer vegetation, using mangroves as a model system. We performed mesocosm experiments that mimicked sediment disturbance as (i) accretion/burial of plants and (ii) erosion/excavation of plants of different magnitudes and temporal distribution in combination with water movement and inundation stress. 3. Cumulative sediment disturbance reduced seedling survival, with the faster-growing Avicennia alba showing less mortality than the slower-growing Sonneratia alba. The presence of the additional stressors (inundation and water movement) predominantly reduced the survival of S. alba. 4. Non-lethal accretion treatments increased shoot biomass of the seedlings, whereas non-lethal erosion treatments increased root biomass allocation. This morphological plasticity in combination with the abiotic disturbance history determined how much maximum erosion the seedlings were able to withstand. 5. Synthesis and applications. Seedling survival in dynamic sedimentary environments is determined by the frequency and magnitude of sediment accretion or erosion events, with non-lethal events causing feedbacks to seedling stability. Managers attempting restoration of mangroves, salt marshes, dunes and riparian vegetation should recognize sediment dynamics as a main bottleneck to primary colonization. The temporal distribution of erosion and accretion events has to be evaluated against the ability of the seedlings to outgrow or adjust to disturbances. Our results suggest that selecting fast-growing pioneer species and

  1. Origin of New Faculty in Sedimentary Petrology at Ph.D.-Granting Universities in the United States and Canada.

    Science.gov (United States)

    Thornton, Scott E.

    1981-01-01

    To aid prospective graduate students in sedimentary petrology who wish to teach at colleges or universities, 121 doctoral graduates in this field are traced to their present appointments in higher education. Only 31 percent of these graduates attained this career goal. (Author/WB)

  2. Complete Genome Sequence of Cryobacterium arcticum Strain PAMC 27867, Isolated from a Sedimentary Rock Sample in Northern Victoria Land, Antarctica.

    Science.gov (United States)

    Lee, Jaejin; Cho, Ahnna; Yang, Jae Young; Woo, Jusun; Lee, Hong Kum; Hong, Soon Gyu; Kim, Ok-Sun

    2016-01-01

    Cryobacterium arcticum PAMC 27867, a psychrotolerant, Gram-positive bacterium, was isolated from a sedimentary rock sample collected at Eureka Spurs in northern Victoria Land, Antarctica. Here, we report the genome sequence of C. arcticum PAMC 27867. PMID:27587812

  3. The sedimentary record and petrophysical logs from the Spanish Central Pyrenees: Implications for paleoclimate change in the Early Devonian

    Czech Academy of Sciences Publication Activity Database

    Slavík, Ladislav; Valenzuela-Ríos, J. I.; Hladil, Jindřich; Chadimová, Leona; Liao, J-Ch.; Hušková, Aneta; Calvo, H.; Hrstka, Tomáš

    2015-01-01

    Roč. 21, - (2015), s. 350-350. ISSN 1608-8166. [International Congress on Stratigraphy /2./. STRATI 2015. 19.07.2015-23.07.2015, Graz] Institutional support: RVO:67985831 Keywords : stratigraphy * Early Devonian * sedimentary record * paleoclimate change * Spanish Central Pyrenees Subject RIV: DB - Geology ; Mineralogy http://www.zobodat.at/pdf/Ber-Inst-Erdwiss-Univ-Graz_21_0001-0437.pdf

  4. Studies on pre-cambrian granites and sedimentary rocks by means of the fission track method and alpha spectrometry

    International Nuclear Information System (INIS)

    Samples of granites and sedimentary rock from the Kaap Valley in South Africa were studied for the microdistribution of U and Th by means of fission track mapping and α spectrometry. A Ra 226 anomaly was found which could not be explained by a strong loss of U. New findings were gained when studying U distribution patterns in the granites. (DG)

  5. Sedimentary cyclicity in early Pleistocene, evaporitic, playa-lake lacustrine deposits in the Guadix-Baza basin (Betic Cordillera, Spain)

    International Nuclear Information System (INIS)

    The Guadix-Baza basin (Betic Cordillera, southern Spain) contains in its eastern sector an early Pleistocene (Gelasian and lowermost Calabrian) sedimentary unit that was deposited in a shallow lacustrine environment. Given that the chronological limits of this unit lie between 2.5 and 1.6 Ma BP, the thickness of its preserved sediments (400 m) and high sedimentation rate (44.4 cm/ka) are remarkable. Numerous sedimentary cycles marked by an alternation of marls and sands are commonly found in the marginal sectors and marls and gypsum in the central sector, which would owe their origins to permanent flooding and evaporation/ re-flooding phases due to global climatic changes. Spectral analyses carried out using Fourier transform have revealed the existence of temporary frequencies associated with sedimentary cycles of between 0.2 and 5.2 ka. The origin of these cycles may be associated with variations in solar radiation and oscillations in the Moons orbital position, which would induce global climatic changes resulting in the rise and fall of the water table of the lake. Autocorrelation analyses conducted separately on the marly and evaporitic levels support this conclusion, as they indicate the existence of significant direct correlations between about 4 to 12 sedimentary cycles, which would correspond to repetitions of the stratigraphic series over a time span of 1.3 to 4 ka. (Author)

  6. Sedimentary basins and continental margin processes - from modern hyper-extended margins to deformed ancient analogues : An introduction

    NARCIS (Netherlands)

    Gibson, George M.; Roure, Francois; Manatschal, Gianreto

    2015-01-01

    Continental margins and their fossilized analogues are important repositories of natural resources. With better processing techniques and increased availability of high-resolution seismic and potential field data, imaging of present-day continental margins and their embedded sedimentary basins, in w

  7. Tectonic and climatic controls on late quaternary sedimentary processes in a neotectonic intramontane basin. (The Pitalito Basin, South Colombia).

    NARCIS (Netherlands)

    Bakker, J.

    1990-01-01

    The present study deals with the influence of tectonics and climatic changes on sedimentation patterns in the Quaternary Pitalito Basin (lat. 1°52'N, long. 76°02'W). This intramontane sedimentary basin is 15 km in width and 20 kin in length and is located in the Eastern Cordillera of the southern Co

  8. The potassic sedimentary rocks in Gale Crater, Mars, as seen by ChemCam on board Curiosity

    Science.gov (United States)

    Le Deit, L.; Mangold, N.; Forni, O.; Cousin, A.; Lasue, J.; Schröder, S.; Wiens, R. C.; Sumner, D.; Fabre, C.; Stack, K. M.; Anderson, R. B.; Blaney, D.; Clegg, S.; Dromart, G.; Fisk, M.; Gasnault, O.; Grotzinger, J. P.; Gupta, S.; Lanza, N.; Le Mouélic, S.; Maurice, S.; McLennan, S. M.; Meslin, P.-Y.; Nachon, M.; Newsom, H.; Payré, V.; Rapin, W.; Rice, M.; Sautter, V.; Treiman, A. H.

    2016-05-01

    The Mars Science Laboratory rover Curiosity encountered potassium-rich clastic sedimentary rocks at two sites in Gale Crater, the waypoints Cooperstown and Kimberley. These rocks include several distinct meters thick sedimentary outcrops ranging from fine sandstone to conglomerate, interpreted to record an ancient fluvial or fluvio-deltaic depositional system. From ChemCam Laser-Induced Breakdown Spectroscopy (LIBS) chemical analyses, this suite of sedimentary rocks has an overall mean K2O abundance that is more than 5 times higher than that of the average Martian crust. The combined analysis of ChemCam data with stratigraphic and geographic locations reveals that the mean K2O abundance increases upward through the stratigraphic section. Chemical analyses across each unit can be represented as mixtures of several distinct chemical components, i.e., mineral phases, including K-bearing minerals, mafic silicates, Fe-oxides, and Fe-hydroxide/oxyhydroxides. Possible K-bearing minerals include alkali feldspar (including anorthoclase and sanidine) and K-bearing phyllosilicate such as illite. Mixtures of different source rocks, including a potassium-rich rock located on the rim and walls of Gale Crater, are the likely origin of observed chemical variations within each unit. Physical sorting may have also played a role in the enrichment in K in the Kimberley formation. The occurrence of these potassic sedimentary rocks provides additional evidence for the chemical diversity of the crust exposed at Gale Crater.

  9. A comparison of burial, maturity and temperature histories of selected wells from sedimentary basins in The Netherlands

    NARCIS (Netherlands)

    Nelskamp, S.; David, P.; Littke, R.

    2008-01-01

    Sedimentary basins in The Netherlands contain significant amounts of hydrocarbon resources, which developed in response to temperature and pressure history during Mesozoic and Cenozoic times. Quantification and modelling of burial, maturity and temperature histories are the major goals of this study

  10. Seasonal melting and the formation of sedimentary rocks on Mars, with predictions for the Gale Crater mound

    CERN Document Server

    Kite, Edwin S; Kahre, Melinda A; Wolff, Michael J; Manga, Michael

    2012-01-01

    A model for the formation and distribution of sedimentary rocks on Mars is proposed. The rate-limiting step is supply of liquid water from seasonal melting of snow or ice. The model is run for a O(10^2) mbar pure CO2 atmosphere, dusty snow, and solar luminosity reduced by 23%. For these conditions snow only melts near the equator, and only when obliquity >40 degrees, eccentricity >0.12, and perihelion occurs near equinox. These requirements for melting are satisfied by 0.01-20% of the probability distribution of Mars' past spin-orbit parameters. Total melt production is sufficient to account for aqueous alteration of the sedimentary rocks. The pattern of seasonal snowmelt is integrated over all spin-orbit parameters and compared to the observed distribution of sedimentary rocks. The global distribution of snowmelt has maxima in Valles Marineris, Meridiani Planum and Gale Crater. These correspond to maxima in the sedimentary-rock distribution. Higher pressures and especially higher temperatures lead to melting...

  11. Late Cenozoic sedimentary process and its response to the slip history of the central Altyn Tagh fault, NW China

    Institute of Scientific and Technical Information of China (English)

    陈正乐; 张岳桥; 陈宣华; 王小凤; A.S.Ramon; W.B.Zack

    2001-01-01

    The ENE-striking Altyn Tagh fault (ATF), extending along the northern edge of the Tibetan Plateau, is one of the major important strike-slip faults, and has been known as one of the key areas to debate the eastward extrusion and crustral shortening models of the Tibetan Plateau during and after India-Asia collision. This paper mainly presents new evidence of Late Cenozoic sedimentary process to reconstruct the slip history of the ATF during the Late Cenozoic. Field measurements and laboratory analyses of the sedimentary characteristics in the Late Cenozoic basins in the central Altyn Tagh fault suggest that Late Cenozoic sedimentary sequence should be divided into three units according to facies changes. The paleo-topography reconstruction shows that the sedimentation in these basins was tightly related with the fault, indicating that the ATF has experienced at least three stages of strike slipping in the Late Cenozoic. New geological data from the Late Cenozoic sedimentary basins and the formation of th

  12. Magnetic properties of different grain-sized particles of sediments from the Okinawa Trough and their relationships to sedimentary environment

    Institute of Scientific and Technical Information of China (English)

    LI Ping; LI Peiying; ZHANG Xiaolong; CAO Chengxiao; XU Xingyong; DU Jun; LIU Lejun

    2005-01-01

    Multiple magnetic parameters were measured for nine different grain-sized fractions separated from the sediment samples that are representatives of four different sedimentary environments of the Okinawa Trough. Based on the measured results, the contributions of different grain-sized particles to total magnetic susceptibility of bulk sediments, the magnetic mineral assemblage and magnetic domain state as well as their relationships to sedimentary environment were discussed. Our research shows that the magnetic mineral is dominated by magnetite with a small amount of hematite and is primarily in pseudo-single-domain state. That indicates that the different sedimentary environments in the Okinawa Trough have certain correlation in material provenance. The magnetic minerals enrich in different grain-sized particles in response to different sedimentary environments. The contribution of the grain sizes from coarse to fine to coarse and fine to the magnetic susceptibility from the west to the east is in accordance with terrigenous material transportation from continental shelf of the East China Sea to the Okinawa Trough. It also shows difference in magnetic properties as a result of some environmental factors.

  13. Experimental study and modelling of physico-chemical mechanisms of clay-concrete interactions in the radioactive waste geological disposal context

    International Nuclear Information System (INIS)

    These research works are carried out as part of the radioactive wastes geological disposal feasibility study. The current option developed by Andra, includes several cementitious materials in contact with the surrounding Callovo-Oxfordian (COX) (an argillite). Concretes and argillite present very different pore solutions (ionic concentrations and pH). Controlled by the concentrations differences, the aqueous species diffusion in the solids generates chemical and physical disturbances. This study is based on experimental, analytical and numerical works, in order to identify the mechanisms controlling the clayey environment influence on cementitious materials. (author)

  14. The Meuse-Haute Marne underground research laboratory. A scientific research tool for the study of deep geologic disposal of radioactive wastes

    International Nuclear Information System (INIS)

    The Meuse-Haute Marne underground research laboratory, is an essential scientific tool for the achievement of one of the ANDRA's mission defined in the framework of the law from December 30, 1991 about the long-term management of high-level and long-living radioactive wastes. This document presents this laboratory: site characterization, characteristics of the Callovo-Oxfordian clay, and laboratory creation, coordinated experiments carried out at the surface and in depth, and the results obtained (published in an exhaustive way in the 'Clay 2005' dossier). (J.S.)

  15. The Meuse-Haute Marne underground research laboratory. A scientific research tool for the study of deep geologic disposal of radioactive wastes; Le Laboratoire de Recherche souterrain de Meuse/Haute-Marne. Un outil de recherche scientifique pour etudier le stockage geologique profond de dechets radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-07-01

    The Meuse-Haute Marne underground research laboratory, is an essential scientific tool for the achievement of one of the ANDRA's mission defined in the framework of the law from December 30, 1991 about the long-term management of high-level and long-living radioactive wastes. This document presents this laboratory: site characterization, characteristics of the Callovo-Oxfordian clay, and laboratory creation, coordinated experiments carried out at the surface and in depth, and the results obtained (published in an exhaustive way in the 'Clay 2005' dossier). (J.S.)

  16. Transformations minéralogiques et géochimiques induites par la présence d'hydrogène dans un site de stockage de déchets radioactifs

    OpenAIRE

    Truche, Laurent

    2009-01-01

    The aim of this study is to evaluate the abiotic hydrogen reactivity in deep geological nuclear waste storage. One crucial research interest concerns the role of H2 as a reducing agent for the aqueous/mineral oxidised species present in the site. Preliminary batch experiments carried out with Callovo-Oxfordian argilite, synthetic porewater and H2 gas lead to an important H2S production, in only few hours at 250°C to few months at 90°C. In order to explore whether H2S can originate from sulpha...

  17. Formation Conditions and Sedimentary Characteristics of a Triassic Shallow Water Braided Delta in the Yanchang Formation, Southwest Ordos Basin, China.

    Science.gov (United States)

    Liu, Ziliang; Shen, Fang; Zhu, Xiaomin; Li, Fengjie; Tan, Mengqi

    2015-01-01

    A large, shallow braided river delta sedimentary system developed in the Yanchang Formation during the Triassic in the southwest of the Ordos basin. In this braided delta system, abundant oil and gas resources have been observed, and the area is a hotspot for oil and gas resource exploration. Through extensive field work on outcrops and cores and analyses of geophysical data, it was determined that developments in the Late Triassic produced favorable geological conditions for the development of shallow water braided river deltas. Such conditions included a large basin, flat terrain, and wide and shallow water areas; wet and dry cyclical climate changes; ancient water turbulence; dramatic depth cycle changes; ancient uplift development; strong weathering of parent rock; and abundant supply. The shallow water braided river delta showed grain sediment granularity, plastic debris, and sediment with mature composition and structure that reflected the strong hydrodynamic environment of large tabular cross-bedding, wedge cross-bedding, and multiple positive rhythms superimposed to form a thick sand body layer. The branch river bifurcation developed underwater, and the thickness of the sand body increased further, indicating that the slope was slow and located in shallow water. The seismic responses of the braided river delta reflected strong shallow water performance, indicated by a progradation seismic reflection phase axis that was relatively flat; in addition, the seismic reflection amplitude was strong and continuous with a low angle and extended over considerable distances (up to 50 km). The sedimentary center was close to the provenance, the width of the river was large, and a shallow sedimentary structure and a sedimentary rhythm were developed. The development of the delta was primarily controlled by tectonic activity and changes in the lake level; as a result, the river delta sedimentary system eventually presented a "small plain, big front" character. PMID

  18. Flow regulation manipulates contemporary seasonal sedimentary dynamics in the reservoir fluctuation zone of the Three Gorges Reservoir, China.

    Science.gov (United States)

    Tang, Qiang; Bao, Yuhai; He, Xiubin; Fu, Bojie; Collins, Adrian L; Zhang, Xinbao

    2016-04-01

    Since the launch of the Three Gorges Dam on the Yangtze River, a distinctive reservoir fluctuation zone has been created and significantly modified by regular dam operations. Sediment redistribution within this artificial landscape differs substantially from that in natural fluvial riparian zones, due to a specific hydrological regime comprising steps of water impoundment with increasing magnitudes and seasonal water level fluctuation holding a range of sediment fluxes. This study reinterpreted post-dam sedimentary dynamics in the reservoir fluctuation zone by stratigraphy determination of a 345-cm long sediment core, and related it to impact of the hydrological regime. Seasonality in absolute grain-size composition of suspended sediment was applied as a methodological basis for stratigraphic differentiation. Sedimentary laminations with relatively higher proportions of sandy fractions were ascribed to sedimentation during the dry season when proximal subsurface bank erosion dominates source contributions, while stratigraphy with a lower proportion of sandy fractions is possibly contributed by sedimentation during the wet season when distal upstream surface erosion prevails. Chronology determination revealed non-linear and high annual sedimentation rates ranging from 21.7 to 152.1cm/yr. Although channel geomorphology may primarily determine the spatial extent of sedimentation, seasonal sedimentary dynamics was predominantly governed by the frequency, magnitude, and duration of flooding. Summer inundation by natural floods with enhanced sediment loads produced from upstream basins induced higher sedimentation rates than water impoundment during the dry season when distal sediment supply was limited. We thus conclude that flow regulation manipulates contemporary seasonal sedimentary dynamics in the reservoir fluctuation zone, though little impact on total sediment retention rate was detected. Ongoing reductions in flow and sediment supply under human disturbance may

  19. Formation Conditions and Sedimentary Characteristics of a Triassic Shallow Water Braided Delta in the Yanchang Formation, Southwest Ordos Basin, China.

    Directory of Open Access Journals (Sweden)

    Ziliang Liu

    Full Text Available A large, shallow braided river delta sedimentary system developed in the Yanchang Formation during the Triassic in the southwest of the Ordos basin. In this braided delta system, abundant oil and gas resources have been observed, and the area is a hotspot for oil and gas resource exploration. Through extensive field work on outcrops and cores and analyses of geophysical data, it was determined that developments in the Late Triassic produced favorable geological conditions for the development of shallow water braided river deltas. Such conditions included a large basin, flat terrain, and wide and shallow water areas; wet and dry cyclical climate changes; ancient water turbulence; dramatic depth cycle changes; ancient uplift development; strong weathering of parent rock; and abundant supply. The shallow water braided river delta showed grain sediment granularity, plastic debris, and sediment with mature composition and structure that reflected the strong hydrodynamic environment of large tabular cross-bedding, wedge cross-bedding, and multiple positive rhythms superimposed to form a thick sand body layer. The branch river bifurcation developed underwater, and the thickness of the sand body increased further, indicating that the slope was slow and located in shallow water. The seismic responses of the braided river delta reflected strong shallow water performance, indicated by a progradation seismic reflection phase axis that was relatively flat; in addition, the seismic reflection amplitude was strong and continuous with a low angle and extended over considerable distances (up to 50 km. The sedimentary center was close to the provenance, the width of the river was large, and a shallow sedimentary structure and a sedimentary rhythm were developed. The development of the delta was primarily controlled by tectonic activity and changes in the lake level; as a result, the river delta sedimentary system eventually presented a "small plain, big front

  20. Mineralogy and depositional sources of sedimentary interbeds beneath the Idaho National Engineering Laboratory; eastern Snake River Plain, Idaho

    International Nuclear Information System (INIS)

    Idaho State University, in cooperation with the U.S. Geological Survey, and the U.S. Department of Energy, collected 57 samples of sedimentary interbeds at 19 sites at the Idaho National Engineering Laboratory (INEL) for mineralogical analysis. Previous work by the U.S. Geological Survey on surficial sediments showed that ratios detrital of quartz, total feldspars, and calcite can be used to distinguish the sedimentary mineralogy of specific stream drainages at the INEL. Semi-quantitative x-ray diffraction analyses were used to determine mineral abundances in the sedimentary interbeds. Samples were collected from wells at the New Production Reactor (NPR) area, Idaho Chemical Processing Plant (ICPP), Test Reactor Area (TRA), miscellaneous sites, Radioactive Waste Management Complex (RWMC), Naval Reactors Facility (NRF), and Test Area North (TAN). Normalized mean percentages of quartz, feldspar, and carbonate were calculated from sample data sets at each site. Percentages for quartz, feldspar, and carbonate from the NPR, ICPP, TRA, miscellaneous sites, RWMC, and NRF ranged from 37 to 59, 26 to 40, and 5 to 25, respectively. Percentages for quartz, feldspar, and carbonate from wells at Test Area North (TAN) were 24, 10, and 66, respectively. Mineralogical data indicate that sedimentary interbed samples collected from the NPR, ICPP, TRA, miscellaneous sites, RWMC, and NRF correlate with surficial sediment samples from the present day Big Lost River. Sedimentary interbeds from TAN sites correlate with surficial sediment samples from Birch Creek. These correlations suggest that the sources for the sediments at and near the INEL have remained relatively consistent for the last 580,000 years. 12 refs., 4 figs., 3 tabs

  1. Stratigraphic sequence and sedimentary characteristics of Lower Silurian Longmaxi Formation in Sichuan Basin and its peripheral areas

    Directory of Open Access Journals (Sweden)

    Yuman Wang

    2015-03-01

    Full Text Available A high-precision sedimentary environment study of the Lower Silurian Longmaxi Formation is an important subject for shale gas exploration and development in Sichuan Basin and its surrounding areas. On the basis of outcrops and drilling data, its isochronous stratigraphic framework was built according to a particular graptolite zone and an important marker bed, and lithofacies, paleontology, calcareous content, well logging, geochemistry and other geologic information were combined to describe the sedimentary microfacies of Longmaxi Formation and its stratigraphic sequence, sedimentary evolution process and high quality shale distribution features as follows: ① with regional diachronism of the top and the bottom, the Longmaxi Formation is divided into two third-order sequences (SQ1 and SQ2, of which SQ1 is mainly an abyssal sedimentary assemblage deposited in the marine transgression period, and SQ2 is a bathyal to shallow sea sedimentary assemblage deposited in the marine regression period; ② there are eight microfacies such as deep calcareous shelf and deep argillaceous shelf in this formation and the organic-rich shale was mainly deposited in the deep water area of SQ1; and ③ from SQ1 to SQ2, the depocenter moved from the depression area in southern-eastern to northern Sichuan Basin, but the central Sichuan uplift remained an underwater one. It is concluded from this study that: ① shale gas production layers were mainly deposited in SQ1, the southern-eastern depression area was the depocenter in SQ1 and a shale gas enrichment area; and ② black shale in northern Sichuan was deposited in late SQ2, with limited distribution and relatively insufficient exploration potential, but the potential of shale gas exploration in western Hubei area is between southern-eastern and northern Sichuan Basin.

  2. Characteristics and Origin of Sedimentary-Related Manganese Layers in Timor Island, Indonesia

    Directory of Open Access Journals (Sweden)

    Arifudin Idrus

    2014-07-01

    Full Text Available DOI: 10.17014/ijog.v8i4.169Sedimentary-related manganese layers have been discovered in South Central Timor Regency, Timor Island, Indonesia, which is tectonically active and being uplifted due to north-trending tectonic collision between Timor Island arc and Australian continental crust. The manganese layers of 2 to 10 cm-wide interbed with deep sea sedimentary rocks including reddish - reddish brown claystone, radiolarian chert, slate, marl as well as white and pinkish calcilutite of Nakfunu Formations. Stratigraphically, the rock formations are underlain by Bobonaro Formation. Two types of manganese ores found comprise manganese layers and manganese nodule. The manganese layers strongly deformed, lenticular, and segmented, are composed of manganite [MnO(OH], groutite [MnO(OH], pyrolusite (MnO2, lithioporite (Al,Li MnO2(OH2, and hollandite [Ba (Mn4+, Mn2+8O16] associated with gangue minerals including calcite, quartz, limonite [FeO(OH], hematite (Fe2O3, and barite (BaSO4. Whilst the nodule type is only composed of manganite and less limonite. Geochemically, the manganese layers have grade of 63 - 72 wt.% MnO, whereas the nodule one has grade of 63 - 69 wt.% MnO. Generally, iron in Mn ore is very low ranging from 0.2 to 1.54 wt.% Fe2O3, averaged 0.76 wt.%. Hence, Fe/Mn ratio which is very low (0.003 - 0.069, typically indicates a sedimentary origin, which is also supported by petrologic and petrographic data showing layering structure of manganite and lithioporite crystal/grain. Trace element geochemistry indicates that manganese ore was precipitated in a reduction condition. Rare earth element (REE analysis of manganese ore shows an enrichment of cerium (Ce suggesting that the ore is basically originated in a marine environment. The manganese nodule is interpreted to be formed by chemical concretion process of unsoluble metals (i.e. mangan, iron in seawater (hydrogenous and precipitated on deep sea bottom. On the other hand, the manganese

  3. Tectonics of Chukchi Sea Shelf sedimentary basins and its influence on petroleum systems

    Science.gov (United States)

    Agasheva, Mariia; Antonina, Stoupakova; Anna, Suslova; Yury, Karpov

    2016-04-01

    The Chukchi Sea Shelf placed in the East Arctic offshore of Russia between East Siberian Sea Shelf and North Slope Alaska. The Chukchi margin is considered as high petroleum potential play. The major problem is absence of core material from drilling wells in Russian part of Chukchi Shelf, hence strong complex geological and geophysical analyses such as seismic stratigraphy interpretation should be provided. In addition, similarity to North Slope and Beaufort Basins (North Chukchi) and Hope Basin (South Chukchi) allow to infer the resembling sedimentary succession and petroleum systems. The Chukchi Sea Shelf include North and South Chukchi Basins, which are separated by Wrangel-Herald Arch and characterized by different opening time. The North Chukchi basin is formed as a general part of Canada Basin opened in Early Cretaceous. The South Chukchi Basin is characterized by a transtensional origin of the basin, this deformation related to motion on the Kobuk Fault [1]. Because seismic reflections follow chronostratigraphic correlations, it is possible to achieve stratigraphic interpretation. The main seismic horizons were indicated as: PU, JU, LCU, BU, mBU marking each regional unconformities. Reconstruction of main tectonic events of basin is important for building correct geological model. Since there are no drilling wells in the North and South Chukchi basins, source rocks could not be proven. Referring to the North Chukchi basin, source rocks equivalents of Lower Cretaceous Pebble Shale Formation, Lower Jurassic Kingdak shales and Upper Triassic Shublik Formation (North Slope) is possible exhibited [2]. In the South Chukchi, it is possible that Cretaceous source rocks could be mature for hydrocarbon generation. Erosions and uplifts that could effect on hydrocarbon preservation was substantially in Lower Jurassic and Early Cretaceous periods. Most of the structures may be connected with fault and stratigraphy traps. The structure formed at Wrangel-Herald Arch to

  4. Controls and variability of solute and sedimentary fluxes in Antarctic and sub-Antarctic Environments

    Science.gov (United States)

    Zwolinski, Zbigniew

    2015-04-01

    The currently prepared SEDIBUD Book on "Source-to-Sink Fluxes in Undisturbed Cold Environments" (edited by Achim A. Beylich, John C. Dixon and Zbigniew Zwolinski and published by Cambridge University Press) is summarizing and synthesizing the achievements of the International Association of Geomorphologists` (I.A.G./A.I.G.) Working Group SEDIBUD (Sediment Budgets in Cold Environments), which has been active since 2005 (http://www.geomorph.org/wg/wgsb.html). The book comprises five parts. One of them is part about sub-Antarctic and Antarctic Environments. This part "Sub-Antarctic and Antarctic Environments" describes two different environments, namely oceanic and continental ones. Each part contains results of research on environmental drivers and rates of contemporary solute and sedimentary fluxes in selected sites. Apart from describing the environmental conditions of the whole continent of Antarctica and sub-Antarctic islands (Zb.Zwolinski, M.Kejna, A.N.Lastochkin, A.Zhirov, S.Boltramovich) this part of the book characterizes terrestrial polar oases free from multi-year ice and snow covers (Zb.Zwolinski). The detailed results of geoecological and sedimentological research come from different parts of Antarctica. Antarctic continental shelf (E.Isla) is an example of sub-Antarctic oceanic environment. South Shetlands, especially King George Island (Zb.Zwolinski, M.Kejna, G.Rachlewicz, I.Sobota, J.Szpikowski), is an example of sub-Antarctic terrestrial environment. Antarctic Peninsula (G.Vieira, M.Francelino, J.C.Fernandes) and surroundings of McMurdo Dry Valleys (W.B.Lyons, K.A.Welch, J.Levy, A.Fountain, D.McKnight) are examples of Antarctic continental environments. The key goals of the Antarctic and sub-Antarctic book chapters are following: (i) identify the main environmental drivers and rates of contemporary solute and sedimentary fluxes, and (ii) model possible effects of projected climate change on solute and sedimentary fluxes in cold climate environments

  5. The volcanic-sedimentary sequence of the Lousal deposit, Iberian Pyrite Belt (Portugal)

    Science.gov (United States)

    Rosa, Carlos; Rosa, Diogo; Matos, Joao; Relvas, Jorge

    2010-05-01

    The Iberian Pyrite Belt (IPB) is a massive sulfide province that is located in the south of Portugal and Spain, and hosts more than 90 massive sulfide deposits that amount to more than 1850 million metric tonnes of sulfide ore (Tornos, 2006). The ore deposits size, vary from ~1Mt to >100Mt (e.g. Neves Corvo and Aljustrel in Portugal, and Rio Tinto and Tharsis in Spain). The ore deposits are hosted by a submarine sedimentary and volcanic, felsic dominated, succession that constitutes the Upper Devonian to Lower Carboniferous Volcanic and Sedimentary Complex (VSC). The VSC ranges in thickness from approximately 600 to 1300 m (Tornos 2006). The VSC overlies the Phyllite-Quartzite Group (PQ) (Upper Devonian, base unknown) and is overlain by the Baixo Alentejo Flysch Group (Lower to Upper Carboniferous). The Lousal massive sulfide deposit is located in the western part of the IPB and occurs mostly interbedded with black mudstone. The VSC sequence at Lousal mine consists of a mudstone and quartzite sequence (PQ Group) in the lower part of the succession, over which a thick sequence of rhyolitic lavas (>300 m) occurs. Above the rhyolitic lavas there is a thick sequence of black and grey mudstone that hosts the massive sulfide ore bodies, and a rhyolitic sill. The upper part of the VSC sequence consists of a thick mudstone interval that hosts two thick basaltic units, locally with pillows. The rhyolites have small coherent cores, locally with flow bands, that grade to surrounding massive clastic intervals, with large lateral extent. The clasts show jigsaw-fit arrangement in many places and have planar or curviplanar margins and locally are perlitic at the margin. The top contact of these units is in most locations not exposed, which makes difficult to interpret the mode of emplacement. However, the thick clastic intervals, above described, are in accordance with quenching of volcanic glass with abundant water and therefore indicate that quenching of the rhyolites was the

  6. Earthquake ground motion prediction for real sedimentary basins: which numerical schemes are applicable?

    Science.gov (United States)

    Moczo, P.; Kristek, J.; Galis, M.; Pazak, P.

    2009-12-01

    Numerical prediction of earthquake ground motion in sedimentary basins and valleys often has to account for P-wave to S-wave speed ratios (Vp/Vs) as large as 5 and even larger, mainly in sediments below groundwater level. The ratio can attain values larger than 10 in unconsolidated sediments (e.g. in Ciudad de México). In a process of developing 3D optimally-accurate finite-difference schemes we encountered a serious problem with accuracy in media with large Vp/Vs ratio. This led us to investigate the very fundamental reasons for the inaccuracy. In order to identify the very basic inherent aspects of the numerical schemes responsible for their behavior with varying Vp/Vs ratio, we restricted to the most basic 2nd-order 2D numerical schemes on a uniform grid in a homogeneous medium. Although basic in the specified sense, the schemes comprise the decisive features for accuracy of wide class of numerical schemes. We investigated 6 numerical schemes: finite-difference_displacement_conventional grid (FD_D_CG) finite-element_Lobatto integration (FE_L) finite-element_Gauss integration (FE_G) finite-difference_displacement-stress_partly-staggered grid (FD_DS_PSG) finite-difference_displacement-stress_staggered grid (FD_DS_SG) finite-difference_velocity-stress_staggered grid (FD_VS_SG) We defined and calculated local errors of the schemes in amplitude and polarization. Because different schemes use different time steps, they need different numbers of time levels to calculate solution for a desired time window. Therefore, we normalized errors for a unit time. The normalization allowed for a direct comparison of errors of different schemes. Extensive numerical calculations for wide ranges of values of the Vp/Vs ratio, spatial sampling ratio, stability ratio, and entire range of directions of propagation with respect to the spatial grid led to interesting and surprising findings. Accuracy of FD_D_CG, FE_L and FE_G strongly depends on Vp/Vs ratio. The schemes are not

  7. Sedimentary imprints of tsunami and storm deposits on the Shizuoka coastline, south central Japan

    Science.gov (United States)

    Garrett, Ed; Heyvaert, Vanessa M. A.; Fujiwara, Osamu; Brückner, Helmut; Yokoyama, Yusuke; Riedesel, Svenja; Miyairi, Yosuke; Shishikura, Masanobu; De Batist, Marc

    2016-04-01

    Differentiating between the deposits left by extreme wave events - including tsunamis and storms - presents a major challenge for the palaeotsunami and palaeotempestology communities. The coast of Shizuoka Prefecture, south central Japan, is impacted by typhoons and by tsunamis triggered by great subduction zone earthquakes along the adjacent Nankai Trough. A low-lying organic swale close to the town of Shirasuka is well-placed to preserve sedimentary layers left by both event types. The swale lies between a 5 to 10 metre high beach ridge and a 60 to 80 m high riser of the mid-Pleistocene Tenpakubara marine terrace. Investigating the stratigraphy and sedimentology of the site, Komatsubara et al. (2008) identified seven sand layers and attributed these to four tsunamis and one storm, with two sand layers identified as of terrestrial origin. Revisiting the site, we adopted a multi-proxy approach to further analyse the characteristics of selected deposits. We visualise the stratigraphy of retrieved vibrocores in 2D with linescan photography and in 3D with X-ray computed tomography. While problems remain in attempting to fully correlate all sedimentary layers with the published stratigraphy, we suggest that this reflects the difficulties of using a vibrocoring system in an environment characterised by alternating units of unconsolidated sand and compressible humic mud. Nevertheless, by focussing on sand units that are entirely contained within single core sections and by applying Bayesian age models based on new radiocarbon dates, we are able to identify and correlate selected sand layers. Radiocarbon ages, derived from terrestrial plant macrofossils and the acid-insoluble organic fraction of bulk samples sieved to <180 μm, constrain the timing of sand sheet emplacement, facilitating correlation with the historical record. We combine X-ray diffraction, geophysical characterisation and particle size analysis to provide a comprehensive assessment of the variations

  8. Magnetic Fabrics and Paleomagnetism of Sedimentary Rocks: Examining Effects of Compaction and Deformation

    Science.gov (United States)

    Housen, B. A.

    2006-12-01

    Sedimentary rocks provide many important records of the geometry and history of the geomagnetic field, but such records are at times compromised by the effects of depositional processes, soft-sediment deformation, compaction, and tectonic strain. One productive line of research into these effects has been to utilize the well known ability of magnetic anisotropy methods to quantitatively analyze sediment fabrics that result from these processes, and to use these data to evaluate the possibility that the remanence directions in sediments and sedimentary rocks have been altered. Two approaches to this problem will be presented. The first deals with relationships between magnetic fabric shape parameters and paleomagnetic inclination error. The second approach will be to examine the shape distributions of paleomagnetic data, and compare these to the shape distributions of AMS kmin axes from the same rocks. For the first approach, analyses of magnetic fabrics and estimates of paleomagnetic inclination error in the Shikoku Basin (ODP Site 1173) sediments indicate that both initial deposition and post-depositional compaction play important roles in shallowing of inclination. The sediments down to 344 meters depth have relatively uniform flattening values and fabric-based estimates of mean inclination errors of 3.2° for a = 5, and 5.9°° for a = 2.4. The uniform flattening factors, minor inclination errors, and uniform porosity all suggest that only the initial deposition/consolidation process, rather than burial-related compaction, has influenced the paleomagnetic inclinations of the sediments within this interval. In contrast, sediments below 344 meters depth have flattening factors and calculated inclination errors that monotonically increase with depth, with mean inclination errors of 12.1° for a = 5, and 23.3° for a = 2.4. Decrease of porosity within this same depth interval suggests that burial-related compaction within these hemipelagic sediments is the dominant

  9. The Geomechanics of CO2 Storage in Deep Sedimentary Formations

    Energy Technology Data Exchange (ETDEWEB)

    Rutqvist, Jonny [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-01-12

    This study provides a review of the geomechanics and modeling of geomechanics associated with geologic carbon storage (GCS), focusing on storage in deep sedimentary formations, in particular saline aquifers. The paper first introduces the concept of storage in deep sedimentary formations, the geomechanical processes and issues related with such an operation, and the relevant geomechanical modeling tools. This is followed by a more detailed review of geomechanical aspects, including reservoir stress-strain and microseismicity, well integrity, caprock sealing performance, and the potential for fault reactivation and notable (felt) seismic events. Geomechanical observations at current GCS field deployments, mainly at the In Salah CO2 storage project in Algeria, are also integrated into the review. The In Salah project, with its injection into a relatively thin, low-permeability sandstone is an excellent analogue to the saline aquifers that might be used for large scale GCS in parts of Northwest Europe, the U.S. Midwest, and China. Some of the lessons learned at In Salah related to geomechanics are discussed, including how monitoring of geomechanical responses is used for detecting subsurface geomechanical changes and tracking fluid movements, and how such monitoring and geomechanical analyses have led to preventative changes in the injection parameters. Recently, the importance of geomechanics has become more widely recognized among GCS stakeholders, especially with respect to the potential for triggering notable (felt) seismic events and how such events could impact the long-term integrity of a CO2 repository (as well as how it could impact the public perception of GCS). As described in the paper, to date, no notable seismic event has been reported from any of the current CO2 storage projects, although some unfelt microseismic activities have been detected by geophones. However, potential future commercial GCS operations from large

  10. Evaluating current geomagnetic field models with respect to sedimentary paleomagnetic data: is a dipole sufficient?

    Science.gov (United States)

    Nilsson, Andreas; Snowball, Ian; Muscheler, Raimund

    2010-05-01

    There have been efforts to construct complex global geomagnetic field models constrained by limited paleomagnetic data. Here we present four different versions of a time varying geocentric dipole model for the past approximately 9000 years, which is based on a limited selection of sedimentary paleomagnetic data with good spatial cover. The robustness of the modeling approach is evaluated using modern magnetic observation station data provided by the World Data Centre for Geomagnetism in Edinburgh and we discuss the magnitude of the error introduced by insufficient data coverage. The prediction in terms of directional variations is tested against paleomagnetic data from 64 different sedimentary sites and compared to the output of the CALS3K.3 and CALS7K.2 spherical harmonic models (Korte & Constable 2005, Korte et al. 2009). We find that our dipole estimate can explain the paleomagnetic data almost as well as the CALS3K.3 and CALS7K.2 models. More importantly, specific areas and/or records are identified where there is a significant difference between the performance of the dipole estimate and the spherical harmonic models. We discuss different explanations for these misfits with a focus on the problems involved with geomagnetic field modeling of imperfect paleomagnetic data. Our results suggest that many of the differences between the dipole estimate prediction and the paleomagnetic data can be related to poor paleomagnetic quality and/or the lack of accurate and precise time control inherent to some of the records. These results agree with Valet et al. (2008) who suggested that the CALS7K.2 model probably underestimates the dipole contribution in order to reduce the misfit between the inversion and the data. We conclude that better paleomagnetic data and associated time control can improve the predictions of global geomagnetic models. References: Korte, M. & Constable, C. G. 2005. Continuous geomagnetic field models for the past 7 millennia: 2. CALS7K

  11. Is modern climate variability reflected in compund specific hydrogen isotope ratios of sedimentary biomarkers?

    Science.gov (United States)

    Sachse, D.; Radke, J.; Gleixner, G.

    2003-04-01

    Compound specific hydrogen isotope ratios are emerging as a new palaeoclimatic and palaeohydrological proxy. First reconstructions of palaeoclimate using D/H ratios from n-alkanes are available (Andersen et al. 2001, Sauer et al. 2001, Sachse et al. 2003). However, a systematic approach comparing recent sedimentary biomarkers with climate data is still lacking. We are establishing an ecosystem study of small, ground water fed lakes with known limnology. Nearly all lakes are close to a long-term climate-monitoring site (CARBOEUROPE flux tower site, IAEA precipitation monitoring) delivering ecophysiological and climatic data as temperature, precipitation, evapotranspiration etc. Water, primary biomass, plant, soil and sediment were sampled from lakes and the surrounding ecosystem along a climatic and isotopic gradient in meteoric waters from northern Finland (deltaD: -130 permil vs. VSMOW) to southern Italy (deltaD: -30 permil vs. VSMOW, IAEA 2001). Biomarkers were extracted from the samples to test if climatic variability is reflected in their D/H ratios. First results of the factors influencing the hydrogen isotope composition of sedimentary biomarkers and their use as palaeoclimatic and palaeohydrological proxy will be presented. Andersen N, Paul HA, Bernasconi SM, McKenzie JA, Behrens A, Schaeffer P, Albrecht P (2001) Large and rapid climate variability during the Messinian salinity crisis: Evidence from deuterium concentrations of individual biomarkers. Geology 29:799-802 IAEA (2001) GNIP Maps and Animations. International Atomic Energy Agency, Vienna. Accessible at http://isohis.iaea.org Sachse D, Radke J, Gaupp R, Schwark L, Lüniger G, Gleixner G (2003) Reconstruction of palaeohydrological conditions in a lagoon during the 2nd Zechstein cycle through simultaneous use of deltaD values of individual n-alkanes and delta18O and delta13C values of carbonates. International Journal of Earth Sciences, submitted Sauer PE, Eglington TI, Hayes JM, Schimmelman A

  12. The geomorphic and sedimentary record of past subglacial water outbursts, Sabrina Coast, East Antarctica

    Science.gov (United States)

    Fernandez-Vasquez, R. A.; Domack, E. W.; Lavoie, C.; Gulick, S. P. S.; Saustrup, S., Sr.; Frederick, B.; Leventer, A.; Shevenell, A.; Blankenship, D. D.

    2014-12-01

    The drainage basin of Totten Glacier (TG) comprises nearly one-eighth of the East Antarctic Ice Sheet and contains an estimated ice volume equivalent to 6.9 m of eustatic sea level rise, a value greater than the entire West Antarctic Ice Sheet. Adjacent, and partially covering the area presently corresponding to TG drainage basin, is the Aurora Subglacial Basin, a deep trough that reaches more than 1 km below sea level where geophysical data suggest the existence of numerous subglacial water bodies. Such water bodies maintain zero basal shear stress relatively to the overlying ice. It is theorized that subglacial outburst would decrease the shear stress at the bottom of marine ice sheets near the margin, inducing ice acceleration, thinning and ultimately contributing to the collapse of the ice sheet. In this contribution we present part of the preliminary results of the first geological and geophysical marine survey (NBP1402) to the inner continental shelf off the Sabrina Coast in the Totten Glacier/Moscow University Ice Shelf area, East Antarctica. We describe a set of subglacial features that we interpret as representing the sedimentary and geomorphic record of past subglacial water outbursts. These features, which we refer as "feather moraines", were imaged by high-resolution multichannel seismic (MCS) and CHIRP data to consist of a stack of subglacial sediments separated by erosional unconformities, and were shown in the swath bathymetry to consist of feather-like areas exhibiting cross and cut relationships between different sets, with distinct step-wise borders on the downstream side. They are superimposed on megascale glacial lineations (MSGL) and are elongated in generally the same direction as the MSGLs. The upstream side of the feather moraines coincides with the initiation of the MSGL and an area of drumlins near the limit of the glacial sediments and the outcropping of bedrock. A network of channels carved in bedrock just south of the feather moraines

  13. Effects of man-made structures on sedimentary oxygenation: extent, seasonality and implications for offshore renewables.

    Science.gov (United States)

    Wilding, Thomas A

    2014-06-01

    The number of man-made structures to be placed in the marine environment is set to increase massively in the near future as a consequence of the wide-scale adoption and commercialisation of offshore electricity generation. Marine renewable energy devices (MREDs) interact with their receiving environment and are de-facto artificial reefs. The Loch Linnhe Artificial Reef (LLR) complex is a large-scale experimental facility, with the main matrix consisting of 30 separate reef modules deployed in 10-30 m depth and over a gradient of hydrographic and sedimentological conditions. The LLR offers potential to examine impacts that are analogous to those likely to occur around MREDs. The extent of the impact of the LLR modules on the receiving environment was assessed by determining their effect on sedimentary redox potential, as a function of distance from the reef-edge, and season, using an innovative, hand-held, underwater redox probe. The results are commensurate with the reef-proximal baffling of water flow resulting in the entrapment of drifting phytodetritus. At the least current-exposed reef-group the expected decrease in mean redox, at 80 mm sediment depth, was 80 mV (95% CI 40, 120 mV) but this effect was not observed more than 1 m from the reef edge and only occurred during summer months (water temperature >10 °C). Redox at the reef edge, particularly during summer months, was more variable compared to redox taken at 1 m and 4 m reef-distance and was associated with the patchy distribution of phytodetrital accumulations. At all reef groups, there was no discernible difference in modelled mean redox between observations taken at 1 m and 4 m-reef distance. Artificial structures, including MREDs, may cause quite major sedimentary changes but this evidence suggests that these effects will be of limited spatial scale and, where phytodetrital accumulations occur, are only likely to be detrimental in oxygen-deficient sediments. Where these changes occur at

  14. Depositional Environment of Fine-Grained Sedimentary Rocks of the Sinamar Formation, Muara Bungo, Jambi

    Directory of Open Access Journals (Sweden)

    M. Heri Hermiyanto Zajuli

    2014-07-01

    Full Text Available DOI: 10.17014/ijog.v8i1.153The research area is situated in the northwestern side of South Sumatra Basin, which is a part of Muara Bungo Regency, Jambi Province. The Oligocene Sinamar Formation consists of shale, claystone, mudstone, sandstone, conglomeratic sandstone, and coal-seam intercalations. This research was focused on fine sedimentary rock of Sinamar Formation, such as shale, claystone, and mudstone. Primary data were collected from SNM boreholes which have depths varying from 75 m up to 200 m, and outcrops that were analyzed by organic petrographic method, gas chromatography-mass spectrometry (GC-MS of normal alkanes including isoprenoids, and sterane. The dominant maceral group is exinite, composed of alginite (3.4 - 18%, and resinite (1.6 - 5.6%, while vitrinite maceral consists of tellocolinite 0.4 - 0.6%, desmocollinite 0.4%, and vitrodetrinite 8.4 - 16.6%. Organic petrography and biomarker analyses show that organic materials of shales were derived from high plants and algae especially Botrycoccus species. Botrycoccus and fresh water fish fossil, found in the shale indicate a lacustrine environment.

  15. Geant4 simulations for sedimentary grains in infinite matrix conditions: The case of alpha dosimetry

    International Nuclear Information System (INIS)

    Simulations based on the Geant4 toolkit have been performed in order to reproduce the electromagnetic interactions of alpha particles in a spherical grain embedded in an infinite radioactive matrix and to assess several dosimetric parameters; updated alpha attenuation factors have thus been calculated for a clay matrix. Their sensitivity to the chemical composition of both the coating matrix and the grain, as well as to the water content of the matrix, has also been investigated. Finally, differences between the energetic spectrum of the incident alpha particles and the deposited energy spectrum in the grain have been highlighted for fine and coarse grains, and their impact in terms of alpha dosimetry has been discussed. - Highlights: • We simulate sedimentary grains in an infinite matrix and alpha particles flux. • The dose deposited and the energetic spectra in the grain are studied. • Attenuation factors are calculated for several grain sizes and matrix compositions. • Grain size in regard of alpha range has to be considered for efficiency calculation

  16. Sedimentary underplating at the Cascadia mantle-wedge corner revealed by seismic imaging

    Science.gov (United States)

    Calvert, Andrew J.; Preston, Leiph A.; Farahbod, Amir M.

    2011-08-01

    Earth's largest earthquakes occur in subduction zones, along the boundary between the subducting and overriding plates. Non-volcanic tremor generated by slow slip between the plates is thought to originate on, or near, this boundary. Earthquakes also occur in the down-going plate as fluids are released, and zones of anomalously low seismic velocities observed beneath several subduction zones are interpreted to be the subducting oceanic crust. Yet, the exact location of the plate boundary remains uncertain. Here we interpret a three-dimensional seismic tomography model from the northern Cascadia subduction zone in the northwest USA. We find that the low-velocity zone varies considerably along the Cascadia margin. In places, we observe the low-velocity zone to crop out at the surface and separate from the descending plate at depths of 35-40km. We argue that the low-velocity zone here cannot represent oceanic crust as previously suggested, and instead the zone mostly represents sediments that have been subducted and underplated beneath the North American continent. We also find that tremor signals correlate with the position of the low-velocity zone, implying that slow slip and tremor may be facilitated by trapped fluids and high pore fluid pressures in subducted sedimentary rocks at, or close to the plate boundary. Our results also imply that the plate boundary beneath Cascadia is much deeper than previously thought.

  17. Late Miocene sedimentary environments in south-western Amazonia (Solimões Formation; Brazil)

    Science.gov (United States)

    Gross, Martin; Piller, Werner E.; Ramos, Maria Ines; Douglas da Silva Paz, Jackson

    2011-08-01

    In Miocene times a vast wetland existed in Western Amazonia. Whereas the general development of this amazing ecosystem is well established, many questions remain open on sedimentary environments, stratigraphical correlations as well as its palaeogeographical configuration. Several outcrops located in a barely studied region around Eirunepé (SW Amazonas state, Brazil) were investigated to obtain basic sedimentological data. The observed deposits belong to the upper part of the Solimões Formation and are biostratigraphically dated to the Late Miocene. Vertically as well as laterally highly variable fine-grained clastic successions were recorded. Based on the lithofacies assemblages, these sediments represent fluvial deposits, possibly of an anastomosing river system. Sand bodies formed within active channels and dominant overbank fines are described (levees, crevasse splays/channels/deltas, abandoned channels, backswamps, floodplain paleosols). Lacustrine environments are restricted to local floodplain ponds/lakes. The mollusc and ostracod content as well as very light δ18O and δ13C values, measured on ostracod valves, refer to exclusively freshwater conditions. Based on palaeontological and geological results the existence of a long-lived lake (“Lake Pebas”) or any influx of marine waters can be excluded for that region during the Late Miocene.

  18. Geomicrobiological properties of Tertiary sedimentary rocks from the deep terrestrial subsurface

    Science.gov (United States)

    Suko, Takeshi; Kouduka, Mariko; Fukuda, Akari; Nanba, Kenji; Takahashi, Manabu; Ito, Kazumasa; Suzuki, Yohey

    Microbial metabolic activity within the deep subsurface can potentially impact radionuclide migration during geological disposal of nuclear waste. To evaluate the geomicrobiological properties of Tertiary sedimentary rocks, which are widely distributed in the repository environment in Japan, aseptic and deoxygenated drilling was conducted with the installation of a multi-packer system to collect cores and groundwater. Integrated results from measurements on potential rates of denitrification and pore-size distributions in drill core samples indicated that in situ microbial activity is constrained by the availability of pore spaces larger than 0.1 μm in radius. Comparison of geochemical profiles of porewater extracted from the core samples and groundwater collected within multi-packer intervals revealed that terminal electron acceptors such as nitrite and sulfate were depleted in groundwater. Microbial community structures based on 16S rRNA gene sequences were represented by phylotypes related to Fe-, Mn-, elemental sulfur- and sulfate-reducing bacteria in groundwater. In addition, a phylotype closely related to denitrifying Acidovorax sp. of the β-proteobacteria was dominant in the lower borehole interval. From our results, it is likely that groundwater microorganisms mediate redox reactions that influence the mobility of radionuclides in the deep subsurface.

  19. Humic acids contribution to sedimentary organic matter on a shallow continental shelf (northern Adriatic Sea)

    Science.gov (United States)

    Giani, M.; Rampazzo, F.; Berto, D.

    2010-12-01

    The shallow northern Adriatic Sea receives large river runoff, predominantly from the Po River, which is the main allochthonous source of nutrients and organic matter. The origin and quality of organic matter deposited in the sediments can influence the degradation processes and oxygen consumption in the bottom waters as well as the fate of many pollutants. Therefore the humic acids (HA) were quantified in surface and sub-surface sediments collected in an area of the north-western Adriatic platform south of Po River. HA showed to have a relevant contribution to sedimentary organic matter. HA content in sediments were positively correlated with the organic carbon concentration and negatively with redox potential and pH, particularly in sub-surface reduced sediments, suggesting their important role in the diagenetic processes taking place in anoxic conditions. Elemental composition of HA extracted from surface and sub-surface sediments showed a wide range of variation of the C org/N ratios which could be due to a mixed (terrestrial and marine) origin and/or an elevated bacteria degradation of nitrogen during diagenesis processes in sediments. The spectroscopic ratios A 2/A 4 and A 4/A 6 of HA confirmed a mixed origin with a high degree of condensation of the HA extracted from sediments.

  20. Preliminary Paleomagnetic Results From Tertiary Rocks of Sedimentary Basins in Northern Vietnam and Tectonic Implications

    Science.gov (United States)

    Zhao, X.; Liu, Z.; Le, K.; Zhao, Y.; Hoang, V.; Phan, D.

    2013-12-01

    The South China Sea (SCS) is a classical representative of western Pacific marginal seas and contains records of Cenozoic tectonic events of SE Asia. The SCS has been at the center stage of many first-order tectonic and paleoclimatic events since the Mesozoic. One clear way to evaluate the relationship between tectonic uplift and climate is to study the resulting changes in marginal sea strata. To this end, we will conduct an integrated paleomagnetic and stratigraphic investigation on Tertiary strata from Phu Tho and Yen Bai provinces, northern Vietnam to help understand the causal linkages among geological and tectonic events and their consequences related to the SCS evolution. We will collect paleomagnetic samples at sections where the most continuous, complete, and best preserved Eocene-Miocene successions. Standard paleomagnetic field tests, such as the fold, reversal, and conglomerate tests will be used to determine the relative age of the magnetization. In addition to detailed thermal and alternating field demagnetization and analysis, selected samples will also be subjected to several rock magnetic analyses to identify magnetic carriers in the rocks. In particular, the hysteresis parameters Jrs/Js and Hcr /Hc ratios will enable us to apply techniques for detecting low-temperature remagnetization of sedimentary rocks. Preliminary finding of this ongoing project will be presented.

  1. The Cretaceous Songliao Basin: Volcanogenic Succession,Sedimentary Sequence and Tectonic Evolution, NE China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The Songliao basin (SB) is a superposed basin with two different kinds of basin fills. The lower one is characterized by a fault-bounded volcanogenic succession comprising of intercalated volcanic, pyroclastic and epiclastic rocks. The volcanic rocks, dating from 110 Ma to 130 Ma, are of geochemically active continental margin type. Fast northward migration of the SB block occurred during the major episodes of the volcanism inferred from their paleomagnetic information. The upper one of the basin fill is dominated by non-marine sag-style sedimentary sequence of siliciclastics and minor carbonates. The basin center shifted westwards from the early to late Cretaceous revealed by the GGT seismic velocity structure suggesting dynamic change in the basin evolution. Thus, a superposed basin model is proposed. Evolution of the SB involves three periods including (1) Alptian and preAptian: a retroarc basin and range system of Andes type related to Mongolia-Okhotsk collisional belt (MOCB); (2) Albian to Companian: a sag-like strike-slip basin under transtension related to oblique subduction of the Pacific plate along the eastern margin of the Eurasian plate; (3) since Maastrichtian:a tectonic inverse basin under compression related to normal subduction of the Pacific plate under the Eurasian plate, characterized by overthrust, westward migration of the depocenter and eastward uplifting of the basin margin.

  2. Evaluation of Five Sedimentary Rocks Other Than Salt for Geologic Repository Siting Purposes

    International Nuclear Information System (INIS)

    The US Department of Energy (DOE), in order to increase the diversity of rock types under consideration by the geologic disposal program, initiated the Sedimary ROck Program (SERP), whose immediate objectiv eis to evaluate five types of secimdnary rock - sandstone, chalk, carbonate rocks (limestone and dolostone), anhydrock, and shale - to determine the potential for siting a geologic repository. The evaluation of these five rock types, together with the ongoing salt studies, effectively results in the consideration of all types of relatively impermeable sedimentary rock for repository purposes. The results of this evaluation are expressed in terms of a ranking of the five rock types with respect to their potential to serve as a geologic repository host rock. This comparative evaluation was conducted on a non-site-specific basis, by use of generic information together with rock evaluation criteria (RECs) derived from the DOE siting guidelines for geologic repositories (CFR 1984). An information base relevant to rock evaluation using these RECs was developed in hydrology, geochemistry, rock characteristics (rock occurrences, thermal response, rock mechanics), natural resources, and rock dissolution. Evaluation against postclosure and preclosure RECs yielded a ranking of the five subject rocks with respect to their potential as repository host rocks. Shale was determined to be the most preferred of the five rock types, with sandstone a distant second, the carbonate rocks and anhydrock a more distant third, and chalk a relatively close fourth.

  3. Spatial and seasonal contrasts of sedimentary organic matter in floodplain lakes of the central Amazon basin

    Science.gov (United States)

    Sobrinho, R. L.; Bernardes, M. C.; Abril, G.; Kim, J.-H.; Zell, C. I.; Mortillaro, J.-M.; Meziane, T.; Moreira-Turcq, P.; Sinninghe Damsté, J. S.

    2016-01-01

    In this study, we investigated the seasonal and spatial pattern of sedimentary organic matter (SOM) in five floodplain lakes of the central Amazon basin (Cabaliana, Janauaca, Canaçari, Mirituba and Curuai) which have different morphologies, hydrodynamics and vegetation coverages. Surface sediments were collected in four hydrological seasons: low water (LW), rising water (RW), high water (HW) and falling water (FW) in 2009 and 2010. We investigated commonly used bulk geochemical tracers such as the C : N ratio and the stable isotopic composition of organic carbon (δ13Corg). These results were compared with lignin phenol parameters as an indicator of vascular plant detritus and branched glycerol dialkyl glycerol tetraethers (brGDGTs) to trace the input of soil organic matter (OM) from land to the aquatic settings. We also applied the crenarchaeol as an indicator of aquatic (rivers and lakes) OM. Our data showed that during the RW and FW seasons, the surface sediments were enriched in lignin and brGDGTs in comparison to other seasons. Our study also indicated that floodplain lake sediments primarily consisted of allochthonous, C3 plant-derived OM. However, a downstream increase in C4 macrophyte-derived OM contribution was observed along the gradient of increasing open waters - i.e., from upstream to downstream. Accordingly, we attribute the temporal and spatial difference in SOM composition to the hydrological dynamics between the floodplain lakes and the surrounding flooded forests.

  4. Sedimentary records of metal contamination and eutrophication in Jinhae-Masan Bay, Korea

    International Nuclear Information System (INIS)

    Highlights: ► The bay of Korea becomes eutrophic, with anoxic sediment, as of the late 1930s. ► Metals showed apparent three stages in their accumulation history. ► It is correlated with the development in industrialization and population. ► Hg accumulation, related with coal burning, was started at the late 1900. - Abstract: Historical environmental pollution in a semi-enclosed coastal bay was investigated using high-resolution sedimentary records for Corg, Ntot, CaCO3, δ13C, and δ15N signatures, and trace metals. A temporal increase in organic matter might have been attributable to enhanced primary marine productivity, presumably caused by increased anthropogenic nutrient inputs in the semi-enclosed, eutrophic system. Metal accumulation occurred in three stages: a preindustrial stage before the 1930s with natural concentrations of metals, an industrialization stage (1940s–1970s) with the highest concentrations, and a postindustrial stage (post 1970s) with stable or decreasing concentrations. However, Hg exhibited a different accumulation history, with concentrations increasing in the early 1900s and accelerating after the 1920s, probably in response to coal burning.

  5. A five-century sedimentary geochronology of biomass burning in Nicaragua and Central America

    International Nuclear Information System (INIS)

    In spite of the extensive use of fire as an agricultural agent in Central America today, little is known of its history of biomass burning or agriculture. As an indicator of the burning practices on the adjacent land, a sedimentary record of carbonized particles sheds light on the trends in frequency and areal extent of biomass burning. This research focuses on a sediment core recovered from an anoxic site in the Pacific Ocean adjacent to the Central American Isthmus and reports a five-century record of charcoal deposition. The research illustrates that biomass burning has been an important ecological factor in the Pacific watershed of Central America at least during the past five centuries. Fluxes of charcoal have generally decreased toward the present suggesting a reduction in the charcoal source function. Perhaps, five centuries ago, the frequency of biomass burning was greater than it is today, larger areas were burned, or biomass per unit area of burned grassland was greater. The major type of biomass burned throughout this five-century period has been grass, as opposed to woods, indicating that any major deforestation of the Pacific watershed of Central America occurred prior to the Conquest

  6. Organotemplate structures in sedimentary manganese carbonates of the Neoproterozoic Penganga Group, Adilabad, India

    Indian Academy of Sciences (India)

    Joydip Mukhopadhyay; Jens Gutzmer; Nicolas J Beukes

    2005-06-01

    Manganese carbonates interstratified with bedded chert in the Chanda Limestone of the Neoproterozoic Penganga Group at Adilabad, south India, have been studied for possible evidence that microbiota played a role in the mediation of early diagenetic Mn-carbonate formation in Precam- brian marine sedimentary successions. The manganese carbonate and chert beds occur within a below wave base, deep-water distally steepened ramp succession. High resolution SEM petrogra- phy of the manganese carbonates revealed two basic morphologies — spherical to oval-cylindrical shaped microconcretions, and tubular to irregular, elongated, film-like microstructures. Infolded filmy to hollow tubular strand-like internal morphologies of the spherical to oval-cylindrical shaped microconcretions suggest their microbial affinity. The tubular and film morphologies with mesh- like interconnections closely resemble architectures of microbial extracellular polymeric substance (EPS). Mineralization took place on these organotemplates by the process of permineralization as well as replacement in an early diagenetic pore-water environment with reduction of higher manganese oxy-hydroxides by organic matter and consequent increase in dissolved carbonate.

  7. Sedimentary petrology of oil well rock cores; Petrologia sedimentaria de nucleos de rocas de pozos petroleros

    Energy Technology Data Exchange (ETDEWEB)

    Izquierdo M, Georgina; Paredes S, Adriana [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

    2001-07-01

    At the request of PEMEX Exploration and Production (PEP), in the area of Geology of the Gerencia de Geotermia, the necessary methodology has been integrated to carry out the geologic characterization of cores obtained during the oil well drilling. The integrated studies have been of utility for PEMEX, because they provide detailed information on the processes, conditions of deposition and diagenesis that occur in sedimentary rocks. On the other hand, this geologic information contributes to the update of the geologic model of the field in study. [Spanish] A solicitud de PEMEX Exploracion y Produccion (PEP), en el area de Geologia de la Gerencia de Geotermia, se ha integrado la metodologia necesaria para llevar a cabo la caracterizacion geologica de nucleos obtenidos durante la perforacion de pozos petroleros. Los estudios integrados han sido de utilidad para PEMEX, pues proporcionan informacion detallada sobre los procesos, condiciones de depositacion y diagenesis que ocurren en rocas sedimentarias. Por otro lado, esta informacion geologica contribuye a la actualizacion del modelo geologico del campo en estudio.

  8. Sedimentary lake records of Northern Amazon: the radiocarbon dating as a tool for paleoenvironmental assessment

    International Nuclear Information System (INIS)

    The present work focused the radiocarbon technique for calculating fluxes of tracers in core sediments, which are used to point out paleoenviromental changes. This study was developed in a lake watershed located in one of the most northen portions in the Brazilian Amazon (Caracarana Lake)covering a wide boundary region, where the tropical rain forest changes suddenly to savanna. The sediment cores were taken bya avibrational-corer device placed at the top of aluminium tubes and samples in 1cm-section, considering the sedimentary facies. The samples for radiocarbon dating were analysed by radiometric technique, measuring the 14 C content in a liquid scintillation spectrometer for extended countings , or by AMs (accelerator-mass-spectrometer) measurements for poor-carbon samples. The total organic carbon (TOC) was analysed by a CHN analyser and the minerals (Kaolinite, Quartz, Calcite and Silice Amorphous) were quantified by FTIR spectrometry (Fourier Transformed Infra-Red). The Caracarana Lake core (RR94-9), considered for this study, was the most clear and continous lacustrine record amd showed a good agreement with the results obtained for the other studies in Amazonia and South America, regarding to the optimum holocenic climatic phase. We conclude, supported by the correlation between the silice amorphous and TOC and among the three detrial minerals, that the rise to Caracarana Lake as well as other ones situated in this region was hapenned in very modern times, during the mid and early Holocene, comprising the last few millennia. (author). 16 refs., 3 figs., 1 tab

  9. Sedimentary processes and development of the Zenisu deep-sea channel, Philippine Sea

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Zenisu deep-sea channel originated from a volcanic arc region, Izu-Ogasawara Island Arc, and vanished in the Shikoku Basin of the Philippine Sea. According to the swath bathymetry, the deep-sea channel can be divided into three segments. They are Zenisu canyon, E-W fan channel and trough-axis channel. A lot of volcanic detritus were deposited in the Zenisu Trough via the deep-sea channel because it originated from volcanic arc settings. On the basis of the swath bathymetry, submersible and seismic reflection data, the deposits are characterized by turbidite and debrite deposits as those in the other major deep-sea channels. Erosion or few sediments were observed in the Zenisu canyon, whereas a lot of turbidites and debrites occurred in the E-W channel and trough axis channel. Cold seep communities, active fault and fluid flow were discovered along the lower slope of the Zenisu Ridge. Vertical sedimentary sequences in the Zenisu Trough consist of the four post-rift sequence units of the Shikoku Basin, among which Units A and B are two turbidite units. The development of Zenisu canyon is controlled by the N-S shear fault, the E-W fan channel is related to the E-W shear fault, and the trough-axis channel is related to the subsidence of central basin.

  10. A New Inversion Method of Sedimentary Strata For Deriving Double Parameters and Its Applications

    Institute of Scientific and Technical Information of China (English)

    GUO Hua; LIU Cai; LI Yue; YANG Baojun

    2002-01-01

    The inverse problem of wave equation is the importance of study not only in seismic prospecting but also in applied mathematics. With the development of the research, the inverse methods of 1 - D wave equations have been trending towards the multiple parameters inversion . We have obtained an inverse method with double -parameter, in which medium density and wave velocity can be derived simultaneously. In this paper, to increase the inverse accuracy, the method is improved as follows. Firstly, the formula in which the Green Function is omitted are derived and used. Secondly, the regularizing method is reasonable used by choosing the stable function. With the new method, we may derive elastic parameter and medium density or medium density and wave velocity. Thus, lithology parameters for seismic prospecting may be obtained.After comparing the derived values from the new method with that from previous method, we obtain the new method through which substantially improve the derived accuracy . The new method has been applied to real depths inversion for sedimentary strata and volcanic rock strata in Chaoyanggou Terrace of Songliao Basin in eastern China. According to the inverse results,the gas - bearing beds are determlned.

  11. Advanced Horizontal Well Recirculation Systems for Geothermal Energy Recovery in Sedimentary Formations

    Energy Technology Data Exchange (ETDEWEB)

    Mike Bruno; Russell L. Detwiler; Kang Lao; Vahid Serajian; Jean Elkhoury; Julia Diessl; Nicky White

    2012-09-30

    There is increased recognition that geothermal energy resources are more widespread than previously thought, with potential for providing a significant amount of sustainable clean energy worldwide. Recent advances in drilling, completion, and production technology from the oil and gas industry can now be applied to unlock vast new geothermal resources, with some estimates for potential electricity generation from geothermal energy now on the order of 2 million megawatts. Terralog USA, in collaboration with the University of California, Irvine (UCI), are currently investigating advanced design concepts for paired horizontal well recirculation systems, optimally configured for geothermal energy recovery in permeable sedimentary and crystalline formations of varying structure and material properties. This two-year research project, funded by the US Department of Energy, includes combined efforts for: 1) Resource characterization; 2) Small and large scale laboratory investigations; 3) Numerical simulation at both the laboratory and field scale; and 4) Engineering feasibility studies and economic evaluations. The research project is currently in its early stages. This paper summarizes our technical approach and preliminary findings related to potential resources, small-scale laboratory simulation, and supporting numerical simulation efforts.

  12. The Magilligan beach ridge plain (Northern Ireland, UK): A detailed sedimentary approach

    Science.gov (United States)

    Tillmann, Tanja; Surmann, Kirstin; Cooper, Andrew

    2015-04-01

    Beach ridges are a common geological feature on prograded sandy coasts . Beach ridges and their subsurface deposits record past coastal processes and are indicators of previous shoreline position, shape and sea level. This work presents preliminary results and provides new information about the late Holocene development of the Magilligan Foreland in Northern Ireland (UK). The triangular beach-ridge plain of Magilligan was formed in the early and mid-Holocene as a consequence of land and sea level change and sediment abundance. The focus of the investigations is a detailed grain size analysis of beach ridge deposits using the settling tube method. The main aim is to distinguish the beach ridge deposits from the aeolian dune sand cover and to draw conclusions about the development and sedimentary formation of the beach ridges. A semi-continuous outcrop of the upper units of the beachridge plain is preserved along the coastline. The geological descriptions in the field show significant differences between adjacent outcrops and grain size analysis was undertaken to distinguish aeolian and swash-lain sediemnts. Buried soil layers and unconformities helped to define the palaeotopography which consist of a sequence of beach ridge crests and inter-ridge depressions. The beach ridges of the subsurface are independent of the modern dune topography. There are more beach ridges than previously thought.

  13. Use of laboratory simulated pyrolysis in tracing the history of sedimentary organic matter

    Science.gov (United States)

    Kaplan, I. R.; Tannenbaum, E.; Huizinga, B. E.

    1986-01-01

    Results from laboratory simulated pyrolyses experiments show that in addition to depth of burial, preservation of kerogen, and hence any morphologic structure in it, is also dependent on the mineral matrix with which it is associated. In the presence of clay minerals, and especially under dry conditions, extractable lipids released during kerogen decomposition are more rapidly destroyed than in the presence of calcite or chert matrices. The result is production of gas, polar bitumen and pyrobitumen and destruction of biomarkers. During such an early reorganization of the kerogen, the biomarker constituents can be destroyed, or unrecognizably altered. The above process of organic residues maturation appears to be inhibited in the presence of water and is significantly reduced where kerogen is hosted in limestones, dolomites or cherts. These minerals have been characteristically found to be the most reliable in yielding morphological fossils and small quantities of extractable bitumen in Archean and Proterozoic rocks. To understand the validity of chemical and morphological fossils, in the early geologic record, it will be necessary to understand the process of kerogen in sedimentary rocks. To test the role of various minerals on the preservation process, kerogen extracted from a variety of rocks has been heated together with montmorillonite, illite and calcite. The kinetics of the process has been monitored and the products quantitatively identified.

  14. Evaluation of Five Sedimentary Rocks Other Than Salt for Geologic Repository Siting Purposes

    Energy Technology Data Exchange (ETDEWEB)

    Croff, A.G.; Lomenick, T.F.; Lowrie, R.S.; Stow, S.H.

    2003-11-15

    The US Department of Energy (DOE), in order to increase the diversity of rock types under consideration by the geologic disposal program, initiated the Sedimary ROck Program (SERP), whose immediate objectiv eis to evaluate five types of secimdnary rock - sandstone, chalk, carbonate rocks (limestone and dolostone), anhydrock, and shale - to determine the potential for siting a geologic repository. The evaluation of these five rock types, together with the ongoing salt studies, effectively results in the consideration of all types of relatively impermeable sedimentary rock for repository purposes. The results of this evaluation are expressed in terms of a ranking of the five rock types with respect to their potential to serve as a geologic repository host rock. This comparative evaluation was conducted on a non-site-specific basis, by use of generic information together with rock evaluation criteria (RECs) derived from the DOE siting guidelines for geologic repositories (CFR 1984). An information base relevant to rock evaluation using these RECs was developed in hydrology, geochemistry, rock characteristics (rock occurrences, thermal response, rock mechanics), natural resources, and rock dissolution. Evaluation against postclosure and preclosure RECs yielded a ranking of the five subject rocks with respect to their potential as repository host rocks. Shale was determined to be the most preferred of the five rock types, with sandstone a distant second, the carbonate rocks and anhydrock a more distant third, and chalk a relatively close fourth.

  15. A discontinuum-based model to simulate compressive and tensile failure in sedimentary rock

    Institute of Scientific and Technical Information of China (English)

    T. Kazerani

    2013-01-01

    The study presented in this paper discusses a discontinuum-based model for investigating strength and failure in sedimentary rocks. The model has been implemented by UDEC to incorporate an innovative orthotropic cohesive constitutive law for contact. To reach this purpose, a user-defined model has been established by creating dynamic link libraries (DLLs) and attaching them into the code. The model repro-duces rock material by a dense collection of irregular-sized deformable particles interacting at their cohesive boundaries which are viewed as flexible contacts whose stress-displacement law is assumed to control the fracture and the fragmentation behaviours of the material. The model has been applied to a sandstone. The individual and interactional effects of the microstructural parameters on the mate-rial compressive and tensile failure responses have been examined. In addition, the paper presents a new methodical calibration procedure to fit the modelling microparameters. It is shown that the model can successfully reproduce the rock mechanical behaviour quantitatively and qualitatively. The study also shows how discontinuum-based modelling can be used to characterize the relation between the microstructural parameters and the macro-scale properties of a material.

  16. Trace metals partitioning among different sedimentary mineral phases and the deposit-feeding polychaete Armandia brevis.

    Science.gov (United States)

    Díaz-de-Alba, Margarita; Huerta-Diaz, Miguel Angel; Delgadillo-Hinojosa, Francisco; Hare, Landis; Galindo-Riaño, M Dolores; Siqueiros-Valencia, Arturo

    2016-02-01

    Trace metals (Cd, Co, Cu, Fe, Mn, Ni, Pb, Zn) were determined in two operationally defined fractions (HCl and pyrite) in sediments from Ensenada and El Sauzal harbors (Mexico). The HCl fraction had significantly higher metal concentrations relative to the pyrite fraction in both harbors, underlining the weak tendency of most trace metals to associate with pyrite. Exceptionally, Cu was highly pyritized, with degrees of trace metal pyritization (DTMP) >80% in both harbors. Dissolved Fe flux measurements combined with solid phase Fe sulfide data indicated that 98 mt of Fe are precipitated as iron sulfides every year in Ensenada Harbor. These Fe sulfides (and associated trace metals) will remain preserved in the sediments, unless they are perturbed by dredging or sediment resuspension. Calculations indicate that dredging activities could export to the open ocean 0.20±0.13 to (0.30±0.56)×10(3) mt of Cd and Cu, respectively, creating a potential threat to marine benthic organisms. Degrees of pyritization (DOP) values in Ensenada and El Sauzal harbors were relatively low (making it a useful biomonitor of sedimentary metal exposure. PMID:26595396

  17. Temporal Trends in Syngenetic Lipid Biomarker Signals from Proterozoic Sedimentary Organic Matter

    Science.gov (United States)

    Love, G. D.; Li, C.; Summons, R. E.

    2008-12-01

    The development of continuous-flow catalytic hydropyrolysis (HyPy) for reproducible recovery of biomarker lipid skeletons covalently-bound within kerogen has proved to be an important analytical breakthrough for ancient lipid biomarker research. The parallel analyses of free (solvent-extractable) and kerogen-bound biomarkers affords more confidence that we have correctly identified syngenetic compounds. Combining HyPy with detailed biomarker product analyzes using metastable reaction monitoring-gas chromatography mass spectrometry (MRM-GC-MS) allows detection of a large suite of biomarker compounds which are usually too low in abundance to be analyzed in detail using conventional GC-MS. Here we compare free and bound lipid biomarker records generated from Paleoproterozoic (ca. 1.7 Ga) to Late Ediacaran age (ca. 542 Ma) strata from marine basins from North and South China, Australia and Oman. Fundamental changes in eukaryotic community structure are evident after the Sturtian glaciation (ca. 713 Ma) from distinctive sterane distributions. In particular, radiations in basal animals (sponges) and chlorophyte microalgae are first apparent in Huqf sedimentary rocks from South Oman Salt Basin. Marine microbial communities were not globally homogenous in contemporaneous Proterozoic settings from comparison of biomarker profiles and this could reflect differences in ocean chemistry, affecting nutrient supply, from basin to basin.

  18. Atlantic 3800-meter radioactive waste disposal site survey (1978): sedimentary, micromorphologic and geophysical analyses. Final report

    International Nuclear Information System (INIS)

    During the period of 22-28 July, 1978, five dives were made in the manned submersible ALVIN into the Atlantic Ocean 3800 meter depth radioactive waste disposal site located in the Hudson Canyon channel approximately 320 kilometers from the Maryland-Delaware coast. A geological description of the site was made by direct examination of the bottom topography, bedrock exposures, sedimentary and erosional processes, and sediment cores collected from the dumpsite area. Observations within a depth range of 3985-3830 meters revealed angular blocks and piles of displaced channel wall rock, boulder and cobble olistoliths of Eocene-age chalks derived from higher elevations on the slope, and bedforms such as ripples and scour marks which imply the existence of periodic strong currents. Local benthic fauna were sparse. Three low-level radioactive waste drums were examined from the submersible, and one was subsequently recovered for corrosion, and concrete deterioration analyses. Photographic and visual evidence suggest that downslope transport of objects such as talus blocks, olistoliths, and radioactive waste drums has occurred in this area

  19. Historical reconstruction of anthropogenic mercury input from sedimentary records: Yeongsan Estuary, South Korea

    Science.gov (United States)

    Williams, Joshua; Dellapenna, Timothy; Louchouarn, Patrick; Lee, Guan-hong

    2015-12-01

    The rapid economic growth of the Republic of Korea (S. Korea) within the last half-century has resulted in a pronounced increase in anthropogenic Hg emission from coal combustion, oil refining, cement production, and waste incineration. The record of increasing atmospheric sources have been investigated with a historical reconstruction of Hg accumulation in 30 sediment cores collected from the Yeongsan Estuary. Within the last several decades, this region has undergone severe anthropogenic alteration, including the construction of an estuarine dam forming the Yeongsan Lake, and installation of numerous seawalls that eliminated vast tidal flats and restricted estuarine circulation. Total mercury concentrations (T-Hg) measured in sediments deposited after 1980 (23.2 ± 9.6 ng g-1; n = 273), were significantly higher than those reported for pre-industrial sediments (i.e. background values: 8.6 ± 2.7 ng g-1; n = 274). An extensive survey of surface samples show that T-Hg concentrations are highest above the dam, with a gradient to lower values further offshore. The concomitant timing of enrichment of T-Hg within the sedimentary record and increased National emissions in Korea suggests that regional sources dominate the input to the Yeongsan Estuary. This indicates that with sufficient regional historic emission data, T-Hg might be utilized as a geochronologic tool to aid in corroborating traditional radioisotopic methods.

  20. Neutron Imaging of Rapid Water Imbibition in Fractured Sedimentary Rock Cores

    Science.gov (United States)

    Cheng, Chu-Lin; Perfect, Edmund; Donnelly, Brendan; Bilheux, Hassina; Tremsin, Anton; McKay, Larry; Distefano, Victoria; Cai, Jianchao; Santodonato, Lou

    2015-03-01

    Advances in nondestructive testing methods, such as neutron, nuclear magnetic resonance, and x-ray imaging, have significantly improved experimental capabilities to visualize fracture flow in various important fossil energy contexts, e.g. enhanced oil recovery and shale gas. We present a theoretical framework for predicting the rapid movement of water into air-filled fractures within a porous medium based on early-time capillary dynamics and spreading over rough fracture surfaces. The theory permits estimation of sorptivity values for the matrix and fracture zone, as well as a dispersion parameter which quantifies the extent of spreading of the wetting front. Dynamic neutron imaging of water imbibition in unsaturated fractured Berea sandstone cores was employed to evaluate the proposed model. The experiments were conducted at the Neutron Imaging Prototype Facility at Oak Ridge National Laboratory. Water uptake into both the matrix and fracture zone exhibited square-root-of-time behavior. Both theory and neutron imaging data indicated that fractures significantly increase imbibition in unsaturated sedimentary rock by capillary action and surface spreading on rough fracture faces. Fractures also increased the dispersion of the wetting front.

  1. Relationship between susceptibility induced field inhomogeneities, restricted diffusion, and relaxation in sedimentary rocks.

    Science.gov (United States)

    Wilson, Robert C; Hürlimann, Martin D

    2006-11-01

    Low field relaxation and diffusion measurements have become essential tools to study the pore space of sedimentary rocks with important practical applications in the field of well logging and hydrocarbon extractions. Even at Larmor frequencies below 2 MHz, diffusion measurements are often affected noticeably by internal field inhomogeneities. These field inhomogeneities are induced by susceptibility contrast between the rock and the fluid and are evident in most sandstones. Using sets of two-dimensional diffusion-relaxation measurements in applied and internal gradients, we study in detail the correlation between the field inhomogeneities, restricted diffusion, and relaxation time in three rocks of different susceptibility. We find that in the sandstone cores, the field inhomogeneities in large pores can be described by a local gradient that scales inversely with relaxation time above 250 ms. At shorter relaxation times, the extracted internal gradients deviate from this scaling relationship and we observe a dependence on diffusion time. This demonstrates that in this case, the internal field has structure on a length scale of a few microns. PMID:16890000

  2. Discordance of the U Pb system in detrital zircons: Implication for provenance studies of sedimentary rocks

    Science.gov (United States)

    Nemchin, Alexander A.; Cawood, Peter A.

    2005-12-01

    Provenance studies involving U / Pb analysis of detrital zircons have become increasingly popular through the application of microanalytical techniques. Adopted one-dimensional methods for the presentation of detrital zircon data, such as probability density distribution plots, generally require various degrees of filtering of discordant analyses. However, a uniform approach for filtering does not exist, making comparison of data from different samples and sedimentary units, as well as different studies of detrital populations, extremely difficult. The problem is further complicated by the need to switch from 207Pb / 206Pb based ages to 206Pb / 238U ages when zircon populations within a sample show a range of ages from Archean to Proterozoic or even Phanerozoic. Ion probe analysis of multiple spots within a single zircon crystal and calculation of an internal isochron can potentially eliminate problems associated with discordance, but this is a time consuming approach. Comparison of internal isochron ages for zircons generated by multiple ion probe intra-grain zircon analyses from a sample of psammite within the Dalradian Supergroup of Scotland with a data set from the same sample based on single grain ion probe analysis using various filtering methods suggests good agreement between the two approaches particularly when filtering is based on the probability of concordance. However, when precise information is required, such as the age of the youngest zircon grains so as to accurately constrain the maximum depositional age of the strata, then multiple analyses of individual zircon grains may be required.

  3. Managing the Cumulative Impacts of Land Uses in the Western Canadian Sedimentary Basin: A Modeling Approach

    Directory of Open Access Journals (Sweden)

    Stan Boutin

    2003-07-01

    Full Text Available This case study from northeastern Alberta, Canada, demonstrates a fundamentally different approach to forest management in which stakeholders balance conservation and economic objectives by weighing current management options from the point of view of their long-term effects on the forest. ALCES®, a landscape-scale simulation model, is used to quantify the effects of the current regulatory framework and typical industrial practices on a suite of ecological and economic indicators over the next 100 yr. These simulations suggest that, if current practices continue, the combined activities of the energy and forestry industries in our 59,000 km2 study area will cause the density of edge of human origin to increase from 1.8 km/km 2 to a maximum of 8.0 km/km2. We also predict that older age classes of merchantable forest stands will be largely eliminated from the landscape, habitat availability for woodland caribou will decline from 43 to 6%, and there will be a progressive shortfall in the supply of softwood timber beginning in approximately 60 yr. Additional simulations involving a suite of "best practices" demonstrate that substantial improvements in ecological outcome measures could be achieved through alternative management scenarios while still maintaining a sustainable flow of economic benefits. We discuss the merits of our proposed approach to land use planning and apply it to the Western Canadian Sedimentary Basin.

  4. Faulting and jointing in sedimentary rocks. Basic concepts and impact on bulk properties

    International Nuclear Information System (INIS)

    Basic aspects of joint and fault analysis in little disturbed sedimentary sequences are discussed, with reference to recent literature and, particularly, to relevant experience from structural reservoir modelling in the oil industry. Jointing is relatively simple, since joints are, by definition, tectonic fractures (non-cohesive partings) on which no displacement has taken place. In contrast, faults - by definition, fractures on which significant slip has taken place - are more localized and irregular in distribution, more variable in orientation, and more complicated to parametrize because of the practical difficulties of defining the slip vector. Small faults and micro-faults can be thought of as forming an interconnected network in zones adjacent to large faults, and in other areas of strain concentration due to displacement variations and/or slip incompatibilities. These zones surround rock volumes of low fracture intensity. The experience gained from the geomechanical and geo-hydraulic modelling of hydrocarbon reservoirs will be relevant to radioactive waste disposal in argillaceous rocks, keeping in mind the long time scale and the special characteristics of clay-rich material. (author)

  5. Stratigraphical analysis of the neoproterozoic sedimentary sequences of the Sao Francisco Basin

    International Nuclear Information System (INIS)

    A stratigraphic analysis was performed under the principles of Sequence Stratigraphy on the neoproterozoic sedimentary sequences of the Sao Francisco Basin (Central Brazil). Three periods of deposition separated by unconformities were recognized in the Sao Francisco Megasequence: (1) Sequences 1 and 2, a cryogenian glaciogenic sequence, followed by a distal scarp carbonate ramp, developed during stable conditions, (2) Sequence 3, a Upper Cryogenian stack homoclinal ramps with mixed carbonate-siliciclastic sedimentation, deposited under a progressive influence of compressional stresses of the Brasiliano Cycle, (3) Sequence 4, a Lower Ediacaran shallow platform dominated by siliciclastic sedimentation of molassic nature, the erosion product of the nearby uplifted thrust sheets. Each of the carbonate-bearing sequences presents a distinct δ13C isotopic signature. The superposition to the global curve for carbon isotopic variation allowed the recognition of a major depositional hiatus between the Paranoa and Sao Francisco Megasequences, and suggested that the glacial diamictite deposition (Jequitai Formation) took place most probably around 800 Ma. This constrains the Sao Francisco Megasequence deposition to the interval between 800 and 600 Ma (the known ages of the Brasiliano Orogeny defines the upper limit). A minor depositional hiatus (700.680 Ma) was also identified separating sequences 2 and 3. Isotopic analyses suggest that from then on, more restricted environmental conditions were established in the basin, probably associated with a first order global event, which prevailed throughout deposition of the Sequence 3. (author)

  6. Sedimentary rock porosity studied by electromagnetic techniques: nuclear magnetic resonance and dielectric permittivity

    Science.gov (United States)

    Ramia, M. E.; Martín, C. A.

    2015-02-01

    The present work involves a comprehensive experimental study of porosity and pore size distribution of sedimentary rocks, from oil fields formations, by means of two electromagnetic techniques, namely proton (1H) nuclear magnetic resonance (NMR) and dielectric complex constant (DCC) as function of the frequency, both providing complementary results. The NMR yields an accurate determination of the relative pore size distribution and both movable and irreducible fluids. The DCC measurement provides the direct current electrical resistivity of the samples with different degrees of hydration. Thus, combining the results of both techniques allows the determination of the tortuosity index, by means of Archie's relation, and from it the average pore channel length. These measurements are performed on fully hydrated (saturated), centrifuged, dried, and cleaned rocks and also on samples with the irreducible fluids. Finally, the results are complemented with capillary pressure measurements to obtain the total volume associated with the pore channels related to the rock permeability. Additionally, the work presents a particular method to use a network analyzer to measure the DCC.

  7. Oxygen and carbon isotopes in ore deposits in sedimentary rocks, ch. 7

    International Nuclear Information System (INIS)

    In this chapter some aspects of the distribution and processes controlling the abundance of 18O and 13C in hydrothermal systems are discussed. The term hydrothermal refers to hot, mineralized fluids which, in this specific case, deposited economic amounts of ore minerals in sedimentary rocks. Such ore minerals contain, only in exceptional cases, significant amounts of oxygen and carbon but both are normally very abundant in the associated gangue minerals: carbonates and silicates. Therefore, most stable isotope investigations which use 18O or 13C are based on the distribution of these isotopes in these gangue minerals and it is evident that the paragenetic relationships between gangue and ore must be fully understood if such data are to yield information about the formation of ore minerals and the origin of fluids and metals. A more detailed discussion concentrates on four genetically different deposits: the Providencia mines in Mexico; the Bluebell Mine in British Columbia (Canada), the Pine Point deposits in the Northwest Territories (Canada), and the Eldorado Mines in the Beaverlodge district in Saskatchewan (Canada)

  8. Pollutant lead deposition in the Gulf of Lions over the last century reconstructed from sedimentary records

    International Nuclear Information System (INIS)

    Investigation of the transient evolution of pollutant lead deposition to the Mediterranean are limited by the lack of continuous records. Indeed, most studies are restricted to limited periods (a few days to a few months) that do not allow a precise monitoring of the marine response to anthropogenic input. We have collected 6 cores sediment cores as part of the MATER ECC program in the Gulf of Lions (NW Mediterranean) to reconstruct high resolution pollutant lead deposition over the past century. We coupled pollutant Pb inventories along with isotopic tracers (excess 210Pb and stable lead isotopes). The mean anthropogenic lead inventory is equal to 101±17 μg/cm2, in good agreement first with lead inventories already calculated in this area, and with the atmospheric fallout over the nearby continental area (as estimated from saltmarsh cores in Camargue. Transient pollutant Pb deposition evidences significant patterns with an increase from 1900 to mid-70's that is consistent with anthropogenic regional emissions. The recent anthropogenic decrease in Pb input is also in agreement with trends in anthropogenic emissions. This decrease in sedimentary inventories is of the same order of magnitude than the atmospheric decrease evidenced by direct measurements , i.e. 31μ12% in sediments and 30% in the atmosphere at the Cap Ferrat for the period 1986-1992. Marine margin sediments appear here as relevant proxies to reconstruct past environmental contaminations over the past century owing to the use of several efficient tracers

  9. Assessment of Deep Seated Geothermal Reservoirs in Selected European Sedimentary Environments

    Science.gov (United States)

    Ungemach, Pierre; Antics, Miklos

    2014-05-01

    Europe at large enjoys a variety of sedimentary environments. They most often host dependable geothermal reservoirs thus favouring the farming of hot fluids, within the low to medium enthalpy range, among which geothermal district heating (GDH) and combined heat and power (CHP) undertakings hold a dominant share. Three selected reservoir settings, addressing carbonate and clastic deposits, the Central part of the Paris Basin, the Southern Germany Molasse Basin in the Münich area and the Netherland Basin respectively will be presented and the exploratory, modeling and development strategies discussed accordingly. Whereas 2D (reprocessed) and 3D seismics have become a standard in matching the distinctive (reef facies, an echelon faulting, carbonate platform layering) features of a deep buried karst and a key to drilling success in the Molasse Basin, thus emphasizing a leading exploratory rationale, the Netherland and Paris Basin instead benefit from a mature data base inherited from extensive hydrocarbon exploration campaigns, with concerns focused on reservoir modeling and sustainable management issues. As a result the lessons learned from the foregoing have enabled to build up a nucleus of expertise in the whole chain from resource identification to reservoir assessment and market penetration. The seismic risk, indeed a sensitive though somewhat emotional issue, which is requiring special attention and due microseismic monitoring from the geothermal community will also be commented.

  10. Sedimentary soils in high erosion, their design and recovery, Armero Farm, Tolima University

    International Nuclear Information System (INIS)

    Since 1984, a recuperation program of soils of sedimentary origin has been developed in the farm of Armero of Tolima University, which up to this year (1996) has already shown many a good positive result. To attain such a remarkable effect in the highly deteriorated soils of this farm, it was decided to develop a project for their conservation consisting of the building of terraces, live and dead hedges and barricades, as well as the planting of fruit and forest trees so that, through a well planned methodology, the community members may learn to design, build, maintain and evaluate practical work oriented towards their own know-how and especially to the recuperation of unproductive areas, together with their integration, at due time, with the land and cattle activity. The soil conservation project began in November, 1983, and today, 12 years after having it been worked out, maintained and evaluated, we can see a land wholly recovered, with abundant native vegetation ready for production, mainly with the setting of perennial crops. Bearing in mind these successful results, our recommendation is to continue to implement this project in the different areas where the setting of soil conservation works is necessary, in order that the benefits obtained may be multiplied through the installment of easy and, especially, very economical set-ups

  11. Seasonal and spatial contrasts of sedimentary organic carbon in floodplain lakes of the central Amazon basin.

    Science.gov (United States)

    Sobrinho, Rodrigo; Kim, Jung-Hyun; Abril, Gwenaël; Zell, Claudia; Moreira-Turcq, Patricia; Mortillaro, Jean-Michel; Meziane, Tarik; Damsté, Jaap; Bernardes, Marcelo

    2014-05-01

    Three-quarters of the area of flooded land in the world are temporary wetlands (Downing, 2009), which play a significant role in the global carbon cycle(Einsele et al., 2001; Cole et al., 2007; Battin et al., 2009; Abril et al., 2013). Previous studies of the Amazonian floodplain lakes (várzeas), one important compartment of wetlands, showed that the sedimentation of organic carbon (OC) in the floodplain lakes is strongly linked to the periodical floods and to the biogeography from upstream to downstream(Victoria et al., 1992; Martinelli et al., 2003). However, the main sources of sedimentary OC remain uncertain. Hence, the study of the sources of OC buried in floodplain lake sediments can enhance our understanding of the carbon balance of the Amazon ecosystems. In this study, we investigated the seasonal and spatial pattern of sedimentary organic matter in five floodplain lakes of the central Amazon basin (Cabaliana, Janauaca, Canaçari, Miratuba, and Curuai) which have different morphologies, hydrodynamics and vegetation coverage. Surface sediments were collected in four hydrological seasons: low water (LW), rising water (RW), high water (HW) and falling water (FW) in 2009 and 2010. We investigated commonly used bulk geochemical tracers such as C:N ratio and stable isotopic composition of organic carbon (δ13COC). These results were compared with lignin-phenol parameters as an indicator of vascular plant detritus (Hedges and Ertel, 1982) and branched glycerol dialkyl glycerol tetraethers (brGDGTs) to trace the soil OC from land to the aquatic settings (Hopmans et al., 2004). Our data showed that during the RW and FW seasons, the concentration of lignin and brGDGTs were higher in comparison to other seasons. Our study also indicated that floodplain lake sediments primarily consisted of a mixture of C3 plant detritus and soil OC. However, a downstream increase in C4 plant-derived OC contribution was observed along the gradient of increasingly open waters, i

  12. Sedimentary Feature in Lake Terkhiin Tsagaan and Lake Ugii, Central Mongolia

    Science.gov (United States)

    Orkhonselenge, Alexander; Davaagatan, Tuyagerel

    2016-04-01

    We present characteristics of lacustrine sediments recorded from Lake Terkhiin Tsagaan and Lake Ugii at near latitudes in Central Mongolia. Physical-chemical properties of eight core sediments collected from these lakes show impact of different montane and prairie landscapes on the lacustrine sediments. Lake Terkhiin Tsagaan indicating a montane landscape with higher contents of organic matter and biogenic silica, and finer sediments differs from Lake Ugii reflecting a prairie landscape with higher contents of carbonates and minerals, and coarser sediments. Stratigraphical sequences of the lacustrine sediments recommend that these two lakes have experienced a numerous of environmental conditions during the arid mid Holocene and humid late Holocene reconstructed from the adjacent lakes in Central Mongolia. These Holocene climatic changes inferred from dramatic fluctuations in temperature and precipitation might have been responsible for the identical environmental conditions, resulting in the sedimentary feature in Lake Terkhiin Tsagaan and Lake Ugii. More investigations with precise dating are thus needed from the both lakes for determining lacustrine sedimentations and reconstructing paleoenvironmental changes in Central Mongolia.

  13. Ripple marks as indicators of Late Ordovician sedimentary environments in Northwest Estonia

    Directory of Open Access Journals (Sweden)

    Hints, Linda

    2008-03-01

    Full Text Available Late Ordovician sedimentary environments promoting the development of ripple marks in shallow shelf carbonate deposits of northern Estonia are analysed. Ripple marks are described using different parameters (wavelength, height, and wave and asymmetry indexes. Rippled bedding is exposed in a large area in the uppermost Keila Stage, on the upper boundary of micritic-peloidal limestones (Pääsküla Member of the Kahula Formation. Beds with ripples are overlain by organodetrital lime­stones (Saue Member of the Kahula Formation transitional to grainstones or mud mounds of the Vasalemma Formation. The content of peloids in the Pääsküla Member is relatively high and their size (0.04–0.06 mm corresponds to the grain size of sediments capable of forming ripple marks. Weakly asymmetrical sinusoidal ripple marks are oriented in a north–south direction and have likely been formed in the shallow-water zone of the shoal at some distance from the shore. The wave-current origin of the studied ripples can be inferred from ripple indexes. Ripples were subjected to some erosion and in the shallowing-upwards conditions a rocky bottom with the Trypanites ichnofacies evolved. The rippled surface terminates a small-scale cycle (parasequence of the depositional sequence.

  14. The petroleum habitat in the post-rift sequences in the Brazilian sedimentary basins

    Energy Technology Data Exchange (ETDEWEB)

    De Figueiredo, A.M.F.D.; Fernandes, G.J.F.; Guimaraes, P.T.M. (Petrobras, Rio de Janeiro (Brazil))

    1991-03-01

    The post-rift sedimentary strata of the Brazilian coastal basins are made of two main sequences: the evaporite and carbonatic Albian-Aptian sequence, and the open-marine Late Albian to Recent sequence, both related to the opening of the South Atlantic Ocean. More than 40 billion barrels of oil-equivalent in place has been found in these sequences, mostly in siliciclastic reservoirs above and below the Aptian salt beds. The productive basins are Campos, Espirito Santo, Sergipe-Alagoas, Potiguar, Ceara, and Santos, but the first one is responsible for more than 60% of the original oil in place discovered in these basins. The hydrocarbon origin, migration, and accumulation models in these sequences are discussed and exemplified by some giant oil fields of Campos and Sergipe-Alagoas basins, where oil is trapped in Aptian conglomerates, Albian carbonates, and Upper Cretaceous to Tertiary turbidite sandstones. The cumulative production in these sequences reaches 958.6 million barrels and the proved exploitable reserve amounts reach 2.7 billion barrels of oil-equivalent. Petrobras' exploratory forecast indicates that the post-rift sequences are the most prolific ones in the Brazilian marginal basins. The oil-equivalent that is expected to be discovered, particularly in deep water areas, where giant oil fields (as the Marlim field) have been found, exceeds the amount that has been discovered until now.

  15. Magmatism in the brazilian sedimentary basins and the petroleum geology; Magmatismo nas bacias sedimentares brasileiras e sua influencia na geologia do petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Thomaz Filho, Antonio; Antonioli, Luzia [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil). Faculdade de Geologia]. E-mails: antoniothomaz@globo.com; antonioli@novanet.com.br; Mizusaki, Ana Maria Pimentel [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Inst. de Geociencias]. E-mail: ana.mizusaki@ufrgs.br

    2008-06-15

    In the recent years, the researches on the magmatic events that occurred in the Brazilian sedimentary basins had shown the importance of these episodes for the hydrocarbons exploration. The generation (heating), migration (structural and petrographic alterations), accumulation (basalt fractures) and migrations barriers (sills and dykes) of the hydrocarbons, produced for these rocks, are cited in the marginal and intra continental Brazilian basins. The magmatism produce the temperature increase in the sedimentary basin, around its intrusion, and this propitiate the maturation of the organic matter contained in the hydrocarbons generating rocks of the basin. At the same time, has been verified that the contacts dykes/sedimentary rocks can represent important ways for the hydrocarbons migrations. Recent studies have shown that the magmatism, in its extrusive manifestations, can be analyzed in view of the possibility of having acted as effective hydrocarbon seals and, in consequence, making possible the accumulation of hydrocarbons generated in the underlying sediments. The magmatism of predominantly basic to intermediary character is generated in the asthenosphere, that is, below the lithosphere. The dykes that had introduced in the basement of our sedimentary basins are good heat conductors and we can expect the geothermal gradients increase in the overlapped sedimentary deposits. The more detailed study of the magmatic processes in the Brazilian sedimentary basins must lead to new forms of hydrocarbons exploration in our sedimentary basins, also in those basins where the traditional exploration activities have not occasioned the waited expected successes. (author)

  16. Sedimentary facies of the central part of radial tidal sand ridge system of the eastern China coast

    Institute of Scientific and Technical Information of China (English)

    Yong YIN; Xinqin ZOU; Dakui ZHU; Jiaxiang HUANG

    2008-01-01

    A unique radial tidal sand ridge system (RTSRS) has developed under a complex tidal current field on the eastern China coast between the Yangtze River delta to the south and the abandoned Yellow River (Huanghe) delta to the north. The present study examines the sedimentary evolution of a ridge-channel pair in the central RTSRS. Three cores, with two on the ridges and one in the channel, were drilled to reveal the late Pleistocene-Holocene deposits of the system. Five sedimentary facies were distinguished, i.e. ridge-shallow subtidal facies, ridge-deep subtidal facies, near-surface channel bottom facies, middle tidal flat facies and low tidal flat facies. The ridge-shallow subtidal facies consists of sandy strata with ripple cross bed-dings, horizontal lamina, and massive beddings. Bioturbation seldom occurs. The ridge-deep subtidal facies is primarily characterized by sandy and muddy interlayers with common flaser and lenticular bedding structures. Bioturbation appears abundantly. Massive and graded sediment sequences of storm origin are pre-sent as characterized by rich shell fragments. The near-surface channel bottom facies consists of loose, soft, clayey silt deposits with deformed sedimentary layers. This facies occurs in the deeper part of the active chan-nels. The middle tidal flat and lower tidal flat facies composed of silt-clay couplets prevailed primarily in the tidal flats. Incomplete sedimentary successions show that coastal plain deposits dominate in the study area during 12-13 ka B.P. The sandy ridge and channel facies became dominant during 4 6 ka B.P. when the sea level receded temporarily. Tidal ridge and channel in the study area became active during the last four decades. Sediment reworking due to typhoon and sandy ridge migration plays a key role in shaping the present radial ridge system.

  17. Study on radon exhalation rate in sedimentary and igneous rocks used as building materials in Tiruchirappalli district, Tamil Nadu, India

    International Nuclear Information System (INIS)

    Tiruchirappalli district is naturally endowed with rich building material resources which are also used in neighboring districts. Hence, measurement of radon level in these building materials is important to assess its impact on human health. The present study was undertaken to measure the activity concentration of radon in 8 sedimentary rock (stone rock) quarries and 6 igneous rocks (granite) quarries. Sealed Can Technique using Solid State Nuclear Track Detector was employed for the measurement of radon emanation. The activity concentration of radon in sedimentary rocks ranged from 18.8 ± 0.3 Bqm-3 to 56.0± 4.8 Bqm-3 with the mean concentration of 29.47 ± 12.6 Bqm-3. However, radon concentrations in igneous rocks are distinctly higher and ranged from 47.8 ± 4.0 Bqm-3 to 570.0 ± 95.0 Bqm-3 with the mean value of 273.5 ± 167.7 Bqm-3. The mean radium concentration (CRa) was recorded in both sedimentary (2.13 ± 0.94 Bqkg-1) and igneous rocks (20.4 ± 12.59 Bqkg-1) were well within the limit prescribed for dwellings (370 Bq kg-1). The mass and surface exhalation rates were also calculated in all the rock samples. The study concludes that the sedimentary rocks and the igneous rocks analyzed were radiologically safe when used as building materials expect the granite rock from Narthamalai (S13) which registers a higher mean radon activity of 570.0 ± 95.0 Bq m-3. (author)

  18. Paleomagnetism of Paleozoic sedimentary rocks from the Karatau Range, Southern Kazakhstan: Multiple remagnetization events correlate with phases of deformation

    OpenAIRE

    U. Kirscher; A. Zwing; Alexeiev, D. V.; Helmut Echtler; Bachtadse, V.

    2013-01-01

    The paleogeography of the Altaids and its kinematic and tectonic evolution during the final collision and amalgamation of Eurasia is still poorly known. Addressing this problem, a paleomagnetic study has been undertaken on Paleozoic sedimentary rocks from the Karatau, Southern Kazakhstan. Stepwise thermal demagnetization reveals the presence of a high-temperature component of magnetization in most samples. Fold tests indicate a syn-folding age of magnetic remanence acquisition at three of the...

  19. Mineralogical correlation of surficial sediment from area drainages with selected sedimentary interbeds at the Idaho National Engineering Laboratory, Idaho

    Energy Technology Data Exchange (ETDEWEB)

    Bartholomay, R.C.

    1990-08-01

    Ongoing research by the US Geological Survey at the INEL involves investigation of the migration of radioactive elements contained in low-level radioactive waste, hydrologic and geologic factors affecting waste movement, and geochemical factors that influence the chemical composition of the waste. Identification of the mineralogy of the Snake River Plain is needed to aid in the study of the hydrology and geochemistry of subsurface waste disposal. The US Geological Surveys project office at the Idaho National Engineering Laboratory, in cooperation with the US Department of Energy, used mineralogical data to correlate surficial sediment samples from the Big Lost River, Little Lost River, and Birch Greek drainages with selected sedimentary interbed core samples taken from test holes at the RWMC (Radioactive Waste Management Complex), TRA (Test Reactors Area), ICPP (Idaho Chemical Processing Plant), and TAN (Test Area North). Correlating the mineralogy of a particular present-day drainage area with a particular sedimentary interbed provides information on historical source of sediment for interbeds in and near the INEL. Mineralogical data indicate that surficial sediment samples from the Big Lost River drainage contained a larger amount of feldspar and pyroxene and a smaller amount of calcite and dolomite than samples from the Little Lost River and Birch Creek drainages. Mineralogical data from sedimentary interbeds at the RWMC, TRA, and ICPP correlate with surficial sediment of the present-day big Lost River drainage. Mineralogical data from a sedimentary interbed at TAN correlate with surficial sediment of the present-day Birch Creek drainage. 13 refs., 5 figs., 3 tabs.

  20. Documented international enquiry on solid sedimentary fossil fuels; Coal: definitions, classifications, reserves-resources and energy potential

    OpenAIRE

    Alpern, B.; Lemos de Sousa, M. J.

    2002-01-01

    This paper deals with all solid sedimentary fossil fuels, i.e. coal, the main one for geological reserves and resources, peat, and oil shales. Definitions of coal ( < 50% ash) and coal seam (thickness and depth limits) are examined in view of an international agreement regarding new concepts for a common reserves and resources evaluation using the same nomenclature. The 50% ash limit, already adopted by UN-ECE for coal definition, allows the creation of a new category—the organic ...

  1. Beneficiation of a Sedimentary Phosphate Ore by a Combination of Spiral Gravity and Direct-Reverse Flotation

    OpenAIRE

    Xin Liu; Yimin Zhang; Tao Liu; Zhenlei Cai; Tiejun Chen; Kun Sun

    2016-01-01

    In China, direct-reverse flotation is proved to be applicable to most phosphate ores. However, because the ratio of froth product is generally high, current direct-reverse technology faces challenges in terms of high reagent consumptions and cost. A new gravity and flotation combined process has been developed for the recovery of collophanite from sedimentary phosphate ore from the beneficiation plant of Hubei, China. In this process, 53% of the collophanite was firstly recovered by gravity s...

  2. Plan of the in-situ heating test in sedimentary soft rock. Phase 3 and Phase 4

    International Nuclear Information System (INIS)

    Research has been conducted on high level radioactive waste geological disposal in sedimentary soft rock. One of the research topics is that the long-term mechanical behaviors of soft rock can be affected by various environmental factors such as temperatures and hydraulic conditions. Therefore, thermo-hydro-mechanical coupled analysis in which changes of temperatures, strains and pore pressures in the surrounding rock mass are measured under heating temperatures higher than 100 degrees centigrade. (author)

  3. Large sedimentary aquifer system and sustainable management: investigations of hydrogeological and geochemical variations in Eocene sand aquifer, south western France.

    OpenAIRE

    Malcuit, Eline; Négrel, Philippe; Petelet Giraud, Emmanuelle; Durst, Pierre

    2010-01-01

    In the sedimentary Aquitaine Basin, the Eocene Sand Aquifer system, mostly confined, represents strategic resources for drinking water, irrigation, gas storage and geothermal resources. Therefore, its quantity and quality issues are essential for the sustainable management in this large region that extends over 116,000 km2 (i.e. one-fifth of the French territory). The Eocene Sand Aquifer system comprises at least five aquifers: Paleocene, Eocene infra-molassic sands, early Eocene, middle Eoce...

  4. Global continental weathering trends across the Early Permian glacial to postglacial transition : correlating high- and low-paleolatitude sedimentary records

    OpenAIRE

    Yang, Jianghai; Cawood, Peter A.; Du, Yuansheng; Feng, Bin; Yan, Jiaxin

    2014-01-01

    Time-equivalent Early Permian sedimentary successions from high-latitude Gondwana basins and from equatorial accumulations in North China, covering the glacial to postglacial transition, display correlatable trends in continental weathering intensity based on chemical index of alteration (CIA) values. The successions display a pattern of CIA values that varies with latitude, similar to modern estuarine suspended sediments. Based on the modern-day CIA-temperature correlation, the glacial Early...

  5. Mineralogical correlation of surficial sediment from area drainages with selected sedimentary interbeds at the Idaho National Engineering Laboratory, Idaho

    International Nuclear Information System (INIS)

    Ongoing research by the US Geological Survey at the INEL involves investigation of the migration of radioactive elements contained in low-level radioactive waste, hydrologic and geologic factors affecting waste movement, and geochemical factors that influence the chemical composition of the waste. Identification of the mineralogy of the Snake River Plain is needed to aid in the study of the hydrology and geochemistry of subsurface waste disposal. The US Geological Surveys project office at the Idaho National Engineering Laboratory, in cooperation with the US Department of Energy, used mineralogical data to correlate surficial sediment samples from the Big Lost River, Little Lost River, and Birch Greek drainages with selected sedimentary interbed core samples taken from test holes at the RWMC (Radioactive Waste Management Complex), TRA (Test Reactors Area), ICPP (Idaho Chemical Processing Plant), and TAN (Test Area North). Correlating the mineralogy of a particular present-day drainage area with a particular sedimentary interbed provides information on historical source of sediment for interbeds in and near the INEL. Mineralogical data indicate that surficial sediment samples from the Big Lost River drainage contained a larger amount of feldspar and pyroxene and a smaller amount of calcite and dolomite than samples from the Little Lost River and Birch Creek drainages. Mineralogical data from sedimentary interbeds at the RWMC, TRA, and ICPP correlate with surficial sediment of the present-day big Lost River drainage. Mineralogical data from a sedimentary interbed at TAN correlate with surficial sediment of the present-day Birch Creek drainage. 13 refs., 5 figs., 3 tabs

  6. Microbially mediated carbon cycling as a control on the δ 13C of sedimentary carbon in eutrophic Lake Mendota (USA): new models for interpreting isotopic excursions in the sedimentary record

    Science.gov (United States)

    Hollander, David J.; Smith, Michael A.

    2001-12-01

    An isotopic study of various carbon phases in eutrophic Lake Mendota (Wisconsin, USA) indicates that the δ 13C composition of sedimentary organic and inorganic carbon has become more negative in response to increasing microbially mediated carbon cycling and processes associated with the intensification of seasonal and long-term eutrophication. Progressive increases in the contributions of isotopically depleted chemoautotrophic and methanotrophic biomass (reflected in the -40 to -90‰ values of hopanols and FAMES), attributed to seasonal and long-term increases in production and expansion of the anaerobic water mass, accounts for carbon isotopic trends towards depleted δ 13C values observed in both seasonal varves and over the past 100 years. Changes in the intensities of certain microbial processes are also evident in the sedimentary geochemical record. During the period of most intense cultural eutrophication, when the oxic-anoxic interface was located close to the surface, methanogenesis/methanotrophy and the oxidation of biogenic methane increased to the extent that significant quantities of 13C-depleted CO 2 were added into the epilimnion. This depleted CO 2 was subsequently utilized by phytoplankton and incorporated into CaCO 3 during biogenically induced calcite precipitation. A comparative study between eutrophic Lakes Mendota and Greifen, further indicate that the extent of nutrient loading in the epilimnion determines whether the δ 13C record of sedimentary organic carbon reflects intensification of microbial processes in the hypolimnion and sediments, or changes in the primary productivity in the photic zone. From this comparison, a series of eutrophication models are developed to describe progressive transitions through thresholds of microbial and eukaryotic productivity and their influence on the δ 13C record of sedimentary carbon. With increasing eutrophication, the models initially predict a negative and then a subsequent positive carbon isotopic

  7. Sedimentary-volcanic tuffs formed during the early Middle Triassic volcanic event in Guizhou Province and their stratigraphic significance

    Institute of Scientific and Technical Information of China (English)

    XIAO Jiafei; HU Ruizhong

    2005-01-01

    The sedimentary-volcanic tuff (locally called "green-bean rock") formed during the early Middle Triassic volcanic event in Guizhou Province is characterized as being thin, stable, widespread, short in forming time and predominantly green in color. The green-bean rock is a perfect indicator for stratigraphic division. Its petrographic and geochemical features are unique, and it is composed mainly of glassy fragments and subordinately of crystal fragments and volcanic ash balls. Analysis of the major and trace elements and rare-earth elements (REE), as well as the related diagrams, permits us to believe that the green-bean rock is acidic volcanic material of the calc-alkaline series formed in the Indosinian orogenic belt on the Sino-Vietnam border, which was atmospherically transported to the tectonically stable areas and then deposited as sedimentary-volcanic rocks there. According to the age of green-bean rock, it is deduced that the boundary age of the Middle-Lower Triassic overlain by the sedimentary-volcanic tuff is about 247 Ma.

  8. Heavy mineral distribution and geochemistry related to sedimentary facies variation within the uraniferous intermediate reefs placers, Witwatersrand Supergroup, South Africa

    International Nuclear Information System (INIS)

    The Intermediate Reefs placers of the Precambrian Central Rand Group, Welkom goldfield, comprise interbedded quartz arenites, quartz wackes, and pyritic U-Au bearing quartz pebble conglomerates which currently are of subeconomic potential. On lithological grounds the Intermediate Reefs are subdivided into two members. The present investigations showed that the lower member is developed as a mature placer which accumulated in a perennial braided stream environment, and the upper one as immature sedimentary deposits which were accumulated under ephemeral conditions. Geochemical and mineragraphic studies reveal that for the Intermediate Reefs zone, brannerite is the principal uranium carrier and that the gold/uranium ratio is low when compared to other reefs of the Welkom goldfield. The studies, furthermore, show that the two members of the Intermediate Reefs differ in the relative abundance of their detrital minerals. It is suggested that these differences are caused by differing lithologies in the respective provenance terranes rather than by variations of the prevailing sedimentary processes. The subeconomic ore grade of the Intermediate Reefs is attributed to: (i) lack of economic minerals in their sedimentary source, (ii) absence of reworkable well mineralized placers in their footwall, and (iii) inadequate hydraulic conditions preventing the efficient accumulation of uraninite and gold. (author). 28 refs, 9 figs, 3 tabs

  9. Deep sedimentary structure model beneath the Osaka plain; Osaka heiya ni okeru shinbu chika kozo no model ka

    Energy Technology Data Exchange (ETDEWEB)

    Miyakoshi, K.; Kagawa, T.; Echigo, T. [Osaka Soil Test, Osaka (Japan)

    1997-05-27

    Restructuring was carried out on a sedimentary basin structure model of the Osaka plain including Osaka Bay by using newly obtained underground structural data. After the Hygoken-nanbu Earthquake of 1995, a large number of underground structure investigations have been performed in Osaka Bay and urban areas of Kobe and Osaka. However, very few surveys have been done in areas peripheral to Osaka Prefecture, such as the Ikoma area. Therefore, an attempt has been made to increase the number of measuring points to acquire underground structural data of these areas. Estimation of basic rock depths has utilized the dominant cycles in H/V spectra obtained from micro vibration survey, and good correlation of the base rock depths derived by a refraction exploration and a deep-bed boring investigation. With regard to bed division and P- and S- wave velocities in sedimentary beds in the Osaka sedimentary basin, an underground structure model was prepared, which was divided into four beds according to the refraction exploration and the micro vibration investigation. Data obtained by using this model agreed well with depth data acquired from physical exploration and other types of investigations. However, no good agreement was recognized in the data for such areas where the basic depth changes abruptly as the Rokko fault and the Osaka bay fault. 6 refs., 8 figs., 2 tabs.

  10. Archaean Crustal Growth, Proterozoic Terrane Amalgamation and the Pan-African Orogeny, as Recorded in the NE African Sedimentary Record.

    Science.gov (United States)

    Najman, Y.; Fielding, L.; Millar, I.; Butterworth, P.; Andò, S.; Padoan, M.; Barfod, D. N.; Kneller, B. C.

    2015-12-01

    The cratons of Central Africa are formed of various blocks of Archaean and Palaeoproterozoic crust, flanked or truncated by Palaeoproterozoic to Mesoproterozoic orogenic belts. The geology of east Africa has largely been shaped by the events of the Pan-African Orogeny when east and west Gondwana collided to form 'Greater Gondwana' at the end of the Neoproterozoic. The Pan-African orogeny in NE Africa involved the collision of Archaean cratons and the Saharan Metacraton with the Arabian Nubian Shield, a terrane comprising Neoproterozoic juvenile oceanic island arcs. Phanerozoic cover sedimentary rocks, eroded from the Pan-African orogenies, blanket much of NE Africa. Detrital data from these Phanerozoic cover sedimentary rocks, and modern rivers draining both the cover the basement, provide a wealth of information on basement evolution, of particular relevance for regions where the basement itself is poorly exposed due to ancient or modern sedimentary cover. From samples collected in Uganda, Ethiopia, Sudan and Egypt, we provide combined U-Pb and Hf-isotope zircon, U-Pb rutile and Ar-Ar mica datasets, heavy mineral analyses, and bulk trace element data, from Archaean basement, Phanerozoic cover and modern river sediment from the Nile and its tributaries to document the evolution of the North African crust. The data document early crust-forming events in the Congo Craton and Sahara Metacraton, phased development of the Arabian Nubian Shield culminating in the Neoproterozoic assembly of Gondwana during the Pan African Orogeny, and the orogen's subsequent erosion, with deposition of voluminous Phanerozoic cover.

  11. Characterizing long period (1--10 sec) ground motions for base isolated structures located in sedimentary basins

    Energy Technology Data Exchange (ETDEWEB)

    Graves, R.W.; Somerville, P.G. [Woodward-Clyde Federal Services, Pasadena, CA (United States)

    1995-12-01

    Many urban regions, including Los Angeles, Portland and Seattle in the United States and Tokyo in Japan, are located above deep sedimentary basins. The conventional approach of estimating ground motions in these environments is to assume that the geology can be characterized by a horizontally stratified medium, and that only the shallowest few tens of meters influence the ground motion characteristics. However, the trapping and amplification of long period (1-10 sec) waves by sedimentary basins can generate amplitudes that are significantly larger than those calculated from simple 1D models of site resonance. This may be of particular concern for base isolated structures which are most sensitive to ground motions in this period range. The recent development of efficient computational methods for modeling seismic wave, propagation in laterally varying geological structure enable the authors to model the effects of sedimentary basins on earthquake generated ground motions. They are now applying this calculation procedure to characterize the ground motions that may be generated in the Puget Trough and the Portland Basin due to large earthquakes on the Cascadia subduction zone, and in the Los Angeles region due to large earthquakes on blind thrust faults beneath the Los Angeles basin.

  12. TECTONO-SEDIMENTARY EVOLUTION OF THE EOCENE TRANSGRESSIVE DEPOSITS IN THE ACIGÖL, BURDUR AND ISPARTA AREAS (SW TURKEY

    Directory of Open Access Journals (Sweden)

    EZHER TOKER

    2010-12-01

    Full Text Available The Eocene transgressive deposits of the Acıgöl, Burdur and Isparta basins are the best exposed of the SW Turkey and shed light on one of the outstanding problems of the tectono-sedimentary evolution during paleotectonic and neotectonic period. In the present paper we describe a tectonic model of the progressive foreland migration of the allochthonous units such as Lycian and Antalya nappes, initialemplacement onto stable carbonate platform in the Early Oligocene, carrying piggy-back basins and incorporating from alluvial fan to deep-marine deposits recognized in these terrigenous successions.In general, the facies and structural observations on the overall Mid-Late Eocene clastic sequences, outcropping in behind the Lycian nappes, indicate: i the alluvial fan to shallow marine settings of the Başçeşme Fm in Acıgöl, ii the Varsakyayla Fm in Burdur and iii proximal to distal flysch facies trend of the Kayıköy Fm in Isparta. The collected data allow us to hypothesize that the Mid-Late Eocene tectono-sedimentary history was characterized by a terrigenous clastics, probably lying on the constructing tectonic edifice and then deformed and covered by a piggy-back like sequence. Thetectono-sedimentary evolution of the Eocene transgressive in SW Turkey has been probably developed through a progressive migration towards the foreland basin.

  13. The impact of sedimentary alkalinity release on the water column CO2 system in the North Sea

    Science.gov (United States)

    Brenner, H.; Braeckman, U.; Le Guitton, M.; Meysman, F. J. R.

    2016-02-01

    It has been previously proposed that alkalinity release from sediments can play an important role in the carbonate dynamics on continental shelves, lowering the pCO2 of seawater and hence increasing the CO2 uptake from the atmosphere. To test this hypothesis, sedimentary alkalinity generation was quantified within cohesive and permeable sediments across the North Sea during two cruises in September 2011 (basin-wide) and June 2012 (Dutch coastal zone). Benthic fluxes of oxygen (O2), alkalinity (AT) and dissolved inorganic carbon (DIC) were determined using shipboard closed sediment incubations. Our results show that sediments can form an important source of alkalinity for the overlying water, particularly in the shallow southern North Sea, where high AT and DIC fluxes were recorded in near-shore sediments of the Belgian, Dutch and German coastal zone. In contrast, fluxes of AT and DIC are substantially lower in the deeper, seasonally stratified, northern part of the North Sea. Based on the data collected, we performed a model analysis to constrain the main pathways of alkalinity generation in the sediment, and to quantify how sedimentary alkalinity drives atmospheric CO2 uptake in the southern North Sea. Overall, our results show that sedimentary alkalinity generation should be regarded as a key component in the CO2 dynamics of shallow coastal systems.

  14. ASTROCHRONOLOGICAL CALIBRATION OF THE UPPER SERRAVALLIAN/LOWER TORTONIAN SEDIMENTARY SEQUENCE AT TREMITI ISLANDS(ADRIATIC SEA, SOUTHERN ITALY

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    FABRIZIO LIRER

    2002-07-01

    Full Text Available A high resolution cyclostratigraphic study was carried out on a cyclicaly bedded succession of late Middle Miocene deep marine deposits from the Tremiti Islands, Adriatic sea (Italy. Astronomical calibration of the sedimentary cycles provides absolute ages for different calcareous plankton bioevents, widely used for intra Mediterranean correlation, in the interval between 11.12 and 12.60 Ma. The sedimentary record of the S. nicola composite section consists of an alternation of indurated, withish coloured, CaCo3 rich and grey less indurated, CaCo3 poor marly beds, at times replaced by red coloured CaCo3 poor marls. Results of direct correlation between the La 90 (1,1 solution of the insolation curve and the cyclic lithologic patterns occurring in the studied sections, combined with results of spectral methodologies applied on the climate sensitive data (CaCo3 and Globigerinoides showed that the classic Milankovitch periodicity can be represented through the modulation forcing of the studied sedimentary records. 

  15. Depositional tracts and stratigraphic architecture of the Itajaí Basin sedimentary sucessions (Neoproterozoic, northeastern Santa Catarina, Brazil

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    Michel Silva Costa

    2015-06-01

    Full Text Available Neoproterozoic sedimentary successions of the Itajaí Basin show depositional trends and a stratigraphic framework characteristics of foreland basin system. The sedimentary environments have developed in basin conditions ranging from deep marine context, transitional shallow marine, to continental. Stratigraphic architecture comprises three depositional tracts (DT: DTI - submarine fans system that records the initial basin sedimentation and involves frontal and distal turbiditic deposits; DTII - transitional to shallow marine depositional system that represents the efective infill fase of basin, and includes deltaic succession with braided channels dominated plain; and DTIII - fluvial braided and alluvial fan depositional system that comprises the final stage of basin sedimentation. Arkoses and greywacke of the DTI present paleocurrent unimodals patterns and general trend to south-southeast, suggesting source area from Santa Catarina Granulitic Complex. The sandstones and conglomerates of DTII and DTIII have opposite paleocurrent pattern, indicating source area from both Metamorphic Brusque Complex and Florianópolis Batolith. Integration of paleoenvironmental and stratigraphic data, with previous information (U-Pb in detrital zircon, allowed a consistent interpretation on the sedimentary evolution and detrital sources of the basin and represent a progress on the discussions on the knowledge of the Itajaí Basin and its significance in the evolutionary context of the Dom Feliciano Belt.