Sample records for caucasus basin northern

  1. The jurassic events in the Greater Caucasus basin (Northern Neotethys and the Neuquén basin (West Gondwana: a comparison

    Dmitry A. Ruban


    Full Text Available Quite a few common tectonic, palaeoenvironmental, and palaeobiological events have been recognized in the Jurassic evolution of the Greater Caucasus basin (Northern Neotethys and the Neuquén basin (West Gondwana. Both basins were originated by the same planetary-scale tectonic force, i.e., by the activity of the Intrapangaean Shear Zone stretching eastwards along the Eurasian margin as the Northern Tethyan Shear Zone. An oxygen depletion occurred in both studied regions in the Toarcian as a result of global anoxia, which provoked a mass extinction. In both basins, the Callovian was a time for the carbonate platform growth, although in the Greater Caucasus, a carbonate platform appeared only in the Late Callovian. A salinity crisis occurred in the Greater Caucasus during the Kimmeridgian-Tithonian, whereas the same took place twice in the Neuquén basin - in the Middle Callovian and in the late Oxfordian-Kimmeridgian. These events were related to the global epoch of evaporite deposition. Some important differences between the considered basins are also documented. Palaeontological data from the Neuquén basin suggest against the mass extinction at the Jurassic-Cretaceous transition. In contrast, data from the Greater Caucasus basin permit to recognize this global event, although its regional peak occurred in the Berriasian. The Jurassic transgressions and regressions in the Greater Caucasus and western Argentina differed, facts that may be explained by the differences in the regional geodynamics. The only common pattern was a stepwise transgression during the Sinemurian-Pliensbachian.

  2. Source classification in the Northern Caucasus

    Chernobay, I. P.; Gabsatarova, I. P.


    Regional records of-well documented mine blasts in the area of Caucasian Mineral Water (Northern Caucasus, Russia) are analyzed to test the efficiency of the spectrogram method and Pg/Lg spectral ratios as discriminants between small earthquakes (magnitude self-training algorithm, based on the comparison of `demeaned' envelopes, which grouped events by means of hierarchical cluster analysis, P/S discriminant, was implemented to classify a data set of 18 months of routine observations. A total of 366 out of 374 records were successfully classified and separated into 19 groups of events. This algorithm is especially useful when data analyzed are from sparse networks or from a region of complicated crust structure where averaging over the network can lead to systematic error.

  3. Oak ecosystem succession of the Northern Caucasus

    Chalaya, Elena; Slepykh, Victor; Efimenko, Natalia; Povolotskaya, Nina


    English oak (Quercus robur L.) along with its well-known good properties has a high sanitary-hygienic and curative potential. Its volatile metabolites (VM) influence bacteriostatically Staphylococcus aureus 209r, oppressing it in vitro by 85% compared with the control, and Escherichia coli by 45%. There is the least amount of epiphytic microorganisms on the leaves of Q. robur L. compared with some tree species [1]. In addition, VM of Q. robur L. have direct milieu (hypotensive) effects on the organism under its canopy, lowering blood pressure by 20-25 mm Hg [2]. A.P. Kazankin (1993) [4] calculated the prehistoric formula of forest species composition of Caucasian Mineral Waters region (Northern Caucasus): 6Qr3Crp1Fr which was based on the theory of calcium-magnesium absorption complex. According to the theory, underground mineral water, soil, forest litter and the leaves of ground vegetation of the area have the same ratio of the cations Ca and Mg - calcium-magnesium index [3]. Hence oldgrowth in the region consisted of oak (Qr) by 60%, hornbeam (Carpinus-Crp) by 30% and ash (Fraxinus-Fr) only by 10%. Currently, the formula of the forests of the region has been changed by man: 5Fr3Crp2Qr. The proportion of oak forests has decreased to 20%, the proportion of ash has increased by 50%, but the proportion of hornbeam hasn't changed. So it is relevant to restore oak forests of the region in the former ratio to other forest-forming species - ash and hornbeam. Taking into consideration the change of economic formation of society in Russia, it is extremely important to restore natural seed oak forests. Therein the luminance of surface areal is a limiting factor. We have calculated that the natural recovery of oak forests is possible providing observation of optimal moisture standards and soil fertility in combination with solar light within 10-24% from the light of open space. Measures for promotion of oak natural regeneration in mountain resorts of the Northern Caucasus

  4. Thermal history, exhumation, uplift, and long-term landscape evolution of the Eastern Great and Northern Lesser Caucasus, Azerbaijan

    Spilger, Tatiana; Glasmacher, Ulrich Anton; Mosar, Jon


    The Caucasus orogen (Great and Lesser Caucasus) is the highest mountain range between Asia and Europe, whose growth takes place since the beginning of the Cenozoic (Mosar et al. 2010). The orogen has evolved as a result of the active north directed convergence of the Arabian plate (Nikishin et al. 2001). The Great Caucasus (GC) represents a doubly verging fold-and-thrust belt, with a per-and a retro wedge actively propagating into the foreland sedimentary basins to the south and to the north (Sholpo 1993). Thermochronometric techniques (fission-track, (U-Th-Sm)/He, each on apatite and zircon) are used to reconstruct the thermal evolution of the upper crust, the subsidence, as well as the rock and surface uplift of the Eastern GC and Northern Lesser Caucasus and to connect them with the thrust kinematics of the GC. Samples were taken along different transects in Eastern GC and Northern Lesser Caucasus in Azerbaijan. Most samples of Eastern GC are Lower Jurassic age sandstones (deep marine and slope facies). Several sedimentary rock samples of Cretaceous, Miocene, Pliocene and Quaternary age were taken from the outcrops in the Kura basin and along rivers in the Eastern GC. Samples of the Lesser Caucasus are igneous and sedimentary origin and have Lower Jurassic to Holocene age. The first AFT-data in the Eastern Great Caucasus were investigated. All researched samples show recessed AF-ages. Most dated sedimentary samples have several populations of apatite minerals. Apatite minerals have low U-concentration (up to 10 ppm). Most dated samples taken in Aalenian sandstone have very young AFT-ages (up to 10 Ma). Some samples show Oligocene AF-ages of 23-28Ma. The preliminary data confirm orogeny in the Eastern Great Caucasus since Oligocene and propagation of orogeny since middle Miocene (Mosar et al. 2010). References Mosar, J., Kangarli, T., Bochud, M., Glasmacher, U.A., Rast, A., Brunet, M.-F. & Sosson, M. 2010. Cenozoic-Recent tectonics and uplift in the Greater

  5. Active deformation processes of the Northern Caucasus deduced from the GPS observations

    Milyukov, Vadim; Mironov, Alexey; Rogozhin, Eugeny; Steblov, Grigory; Gabsatarov, Yury


    The Northern Caucasus, as a part of the Alpine-Himalayan mobile belt, is a zone of complex tectonics associated with the interaction of the two major tectonic plates, Arabian and Eurasian. The first GPS study of the contemporary geodynamics of the Caucasus mountain system were launched in the early 1990s in the framework of the Russia-US joint project. Since 2005 observations of the modern tectonic motion of the Northern Caucasus are carried out using the continuous GPS network. This network encompasses the territory of three Northern Caucasian Republics of the Russian Federation: Karachay-Cherkessia, Kabardino-Balkaria, and North Ossetia. In the Ossetian part of the Northern Caucasus the network of GPS survey-mode sites has been deployed as well. The GPS velocities confirm weak general compression of the Northern Caucasus with at the rate of about 1-2 mm/year. This horizontal motion at the boundary of the Northern Caucasus with respect to the Eurasian plate causes the higher seismic and tectonic activity of this transition zone. This result confirms that the source of deformation of the Northern Caucasus is the sub-meridional drift of the Arabian plate towards the adjacent boundary of the Eastern European part of the Eurasian lithospheric plate. The concept of such convergence implies that the Caucasian segment of the Alpine-Himalayan mobile belt is under compression, the layers of sedimentary and volcanic rocks are folded, the basement blocks are subject to shifts in various directions, and the upper crust layers are ruptured by reverse faults and thrusts. Weak deviation of observed velocities from the pattern corresponding to homogeneous compression can also be revealed, and numerical modeling of deformations of major regional tectonic structures, such as the Main Caucasus Ridge, can explain this. The deformation tensor deduced from the velocity field also exhibits the sub-meridional direction of the major compressional axes which coincides with the direction of


    Dobaev, Igor


    Unfolding in the late 1980s and early 1990s, the religious revival that involved all the traditional confessions, including Islam, existing in Russia spread to the Northern Caucasus. In fact, it added a political dimension to the local forms of Islam and, by the same token, made it more radical. Centrifugal factors caused disunity in North Caucasian Islam on the institutional level when seven independent spiritual administrations replaced the single Spiritual Administration of the North Cauca...

  7. Glacier variations in the Northern Caucasus compared to climatic reconstructions over the past millennium

    Solomina, Olga; Bushueva, Irina; Dolgova, Ekaterina; Jomelli, Vincent; Alexandrin, Mikhail; Mikhalenko, Vladimir; Matskovsky, Vladimir


    In the Northern Caucasus, glacier and climatic variations over the past centuries remain insufficiently documented. In this review, we summarized the high-resolution information on glacier and climate fluctuations in the region for the past millennium and provided a synthesis of these two lines of evidence with respect to regional climate change. The key areas considered in the paper are the Elbrus area, the Teberda and Arkhyz valleys in the Western Caucasus and the Cherek Bezengiisky and Tsey valleys in the Eastern Caucasus, where the most paleoclimatic evidence has been retrieved. We focused on the fluctuation records of the ten glaciers that are best documented. To reconstruct changes in glacier length in the past, we used aerial photos, optical space images, repeated photographs and old maps. The ages of moraines were defined with the help of instrumental records, historical images, old maps, and tree-ring dating. Lichenometry was used as a supplementary tool to determine the relative ages of glacial landforms. We reviewed the collection of control points used for the lichenometric curves and determined the time limit of potential use of this method in the Caucasus to be up to one millennium. High-resolution tree-ring-based hydroclimatic reconstructions in the Northern Caucasus are presented based on the reconstruction of June-September temperature (1595-2012 CE), the mass balance reconstruction of the Garabashi Glacier (1800-2008 CE) and the runoff of the Teberda River (low-frequency variations) for May, July and August for 1850-2005 CE. The synthesis of all the available paleoclimatic records revealed several distinct climatic periods. Evidence of a warm interval (traditionally referred to as the "Arkhyz break in glaciation") preceding the Little Ice Age (LIA) in the Caucasus is based on archeological, palynological, geochemical and pedological data. However, the conclusions concerning the duration and magnitude of this warming are still vague due to the low

  8. The New 2-M RCC Telescope in the Northern Caucasus for Modern Astronomical Research

    Tarady, V. K.; Yatskiv, Ya. S.

    A new 2-m Ritchey-Chretien-Coude (RCC) telescope in the Northern Caucasus (the Kabardin-Balkar Republic, Russian Federation) is nearing being put into operation. It has been developed by the National Academy of Sciences of the Ukraine on the Terskol peak (near Elbrus) which seems to be one of the best sites for astronomical ground observations in terms of its astroclimate. This paper describes the present status of the telescope, its instrumentation and outlines the scientific problems that can be solved using the telescope.

  9. Megalandslide in the Northern Caucasus foredeep (Uspenskoye, Russia): geomorphology, possible mechanism and age constraints

    Pánek, T.; Hradecký, J.; Šilhán, K..; Strom, A. L.; Smolková, V.; Zerkal, O.


    Although worldwide datasets reveal that majority of giant landslides have occurred within the steepest portion of the Earth's landsurface, recent observations have brought evidence that some of the largest landslides originated in the low-relief landscapes and moved upon very gently inclined slip surfaces. Extremely large landslide with volume ~2.8 km3 was detected on the right bank of the Kuban river in the Northern Caucasus foredeep (Russian Federation). Megalandslide with gently inclined (prefer palaeoseismic hypothesis in connection with rupture of some Late Quaternary fault in the vicinity of landslide area. Area of megalandslide is recently subject of intensive denudation marked by activity of numerous shallow landslides, gully erosion and dynamic aggradation (>2 m during last ~300 years) of material within valley floors.

  10. Simulation and reconstruction of parameters of streamflow and glacier mass balance in the Northern Caucasus

    V. G. Konovalov


    Full Text Available The work was aimed at numerical modeling of spatial-temporal variability of the river Terek seasonal (April to September streamflow characteristics and long-term fluctuations of components of annual glacier mass balances in this basin and on the adjacent territories. Mass balance of glaciers Djankuat and Garabashi was calculated. Simulation was performed by means of stochastic modeling and discrete data presenting fields of main meteorological parameters (precipitation, air temperature and humidity having effect on the streamflow. Realization of this approach is complicated by the fact that spatial representativeness of hydrological and meteorological sites are not corresponding one to another. Data on the runoff is clearly related to the total drainage area closed by a gauging station. And for this data we study a relationship with meteorological parameters which are measured at a non-regular observational network whose spatial representativeness is unknown. These stations are generally located beyond the area under investigation (Fig. 2. Similar problem exists when we analyze a relationship between components of the mass balance of individual glaciers (Djankuat and Garabashi and the above climate characteristics measured at some stations located on the whole Caucasus territory. The same takes place when long-term indices of width and density of tree annual rings obtained in upper reaches of the river Kuban’ are used for analysis of variations of the runoff and the glacier mass balance in the river Terek basin located at a distance of 100-150 km from the Kuban’ dendrologic sites.To solve the problem we used a wide number of factors which directly (various information about the climate or indirectly (indices of the climate dryness, wood ring characteristics characterize conditions of formation of annual and seasonal river runoff and components of glacier mass balance in the North Caucasus. Use of all obtained information made possible the

  11. The new 2meter RCC Telescope in the Northern CAucasus (3100m) for Modern Astronomical Research

    Tarady, V.; Yatskiv, Ya.

    A new 2 meter Ritchey-Chretien-Coude telescope in the Northern Caucasus is expected to be ready for astronomical research in late 1995. The telescope is located on the Terskol peak (near Elbrus) with the altitude of 3100 meter. The low atmospheric water vapour content and the high air transparency in the ultraviolet region allow us to infer that the Terskol peak is one of the best sites in Europe for astronomical ground observation. The mean seeing is about 1 arcsec at the Terskol peak. The main parameters of the optical system are as follows: * equivalent focal length is 16000 mm for the Ritchey-Chretien system and 72000 mm for the Coude system; * diameter of the field free from vignetting is 108' for the Ritchey-Chretien system and 5' for another one; *spot concentration is 80% inside the 0.5" circle. The new telescope will be used in investigating the fundamental problems of the star brightness variability, physics of stars and galaxies, studying the planet and satellite atmosphere dynamics. The precise astrometrical problems can also be solved with this telescope. The telescope will be equiped with the following detectors: -CCD Echelle spectrograph in the Coude focus; - astronomical infrared Fourie spectrometre; -digital panoramic polarimeter; -panoramic spectrophotometer with Fabry-Perot interferometer. This project is realized by the joint efforts of the Main Astronomical Observatory in Kiev (Ukrainian Academy of Sciences) and the International Centre for Astronomical and Medical-Ecological Investigations. Proposals for Scientific observation at the Terskol Observatory are encouraged.

  12. Intracanyon basalt lavas of the Debed River (northern Armenia), part of a Pliocene-Pleistocene continental flood basalt province in the South Caucasus

    Sheth, Hetu; Meliksetian, Khachatur; Gevorgyan, Hripsime; Israyelyan, Arsen; Navasardyan, Gevorg


    Late Pliocene to Early Pleistocene (~ 3.25-2.05 Ma), 200-400 m thick basalt lavas outcrop in the South Caucasus region, including the Kars-Erzurum Plateau (northeastern Turkey), the Javakheti Plateau (Georgia-Armenia), and the Lori Plateau (northern Armenia). These fissure-fed, rapidly erupted fluid lavas filled pre-existing river valleys over many tens of kilometres. The basalts exposed in the Debed River canyon, northern Armenia, are ~ 200 m thick and of three morphological types: (1) basal pillow basalts and hyaloclastites, overlain by (2) columnar-jointed pahoehoe sheet flows, in turn overlain by (3) slabby pahoehoe and rubbly pahoehoe flows. The lower and middle lavas show evidence for damming of river drainage, like many lavas of the Columbia River flood basalt province, Scotland, Ireland, and Iceland. There is also evidence for syn-volcanic faulting of the early lavas. Related basalts also outcrop in the Gegham Uplands and the Hrazdan River basin in Armenia. This 3.25-2.05 Ma South Caucasus basalt province, covering parts of Turkey, Georgia and Armenia, has an estimated areal extent of ~ 15,000 km2 and volume of ~ 2250 km3. Because its main geological features are remarkably like those of many continental flood basalt (CFB) provinces, we consider it a true, albeit small, CFB province. It is the smallest and youngest CFB in the world. An analogue closely similar in major features is the Late Miocene Altos de Jalisco CFB province in the western Trans-Mexican Volcanic Belt. Both provinces formed during lithospheric pull-apart and transtensional faulting. Their broader significance is in showing flood basalt size distribution to be a continuum without natural breaks, with implications for geodynamic models.

  13. Sediment Coring of the Proglacial Lake Donguz-Orun (northern Caucasus, Russia)

    Alexandrin, Mikhail; Solomina, Olga; Kalugin, Ivan; Darin, Andrey; Nesje, Atle


    So far, no high-resolution reconstructions of climate and glacier variations based on lake sediment properties are available in Caucasus Mountains. In other presently glaciated regions this approach is proved to be very useful for this purpose (e.g. Nesje et al., 2001, 2011; Bakke, 2005, Nesje, 2009) In this paper we report the first results of the sediment coring of Donguz-Orun Lake (N 43°13'26", E 42°29'35") situated in the upper reaches of Donguz-Orun-Kyol, a tributary of Baksan river in the Elbrus region of Northern Caucasus, a typical proglacial lake dammed by a lateral moraine deposited by the Donguz-Orun Glacier. It is a drainage lake with several inflowing glacial streams and effluent river Donguz-Orun. The surface area is around 105 000 m2 with a water volume of 465 000m3. The average water depth is around 4.5 m, with a maximum water depth of 14 m. The deepest part is found close to the moraine dam in the narrow northern part of the lake. This is normally consistent with this type of glacial lake systems. An intensive gravitational drift of the moraine material towards the lake is observed. These non-rounded moraine boulders constitute a significant part of the lakebed. Lacustrine sediments are present though. The coring campaign from Institute of Geography, Russian Academy of Sciences (August 2012) used a modified piston corer with a 110 mm-diameter plastic tube (Nesje, 1992) mounted on the inflatable catamaran to obtain lake sediments from Lake Donguz-Orun. A 28-cm long core was retrieved from a water depth of around 7 m. The sediments consist of regularly laminated, fine beige clay, with several interlayers of sand. The coring process appeared to be challenging due to the stiffness of clay, which led to extreme bending of the sediment layers in the basal part of the core. The original thickness of the sediments was obviously higher than observed in the core. In order to clarify the recent history of the Donguz-Orun glacier, we used lichenometry and

  14. Nitrogen transformation in alpine soils of the Northern Caucasus: effect of nitrogen source and low temperatures

    Makarov, Mikhail; Ermak, Anton; Malysheva, Tatiana; Mulyukova, Olga


    The alpine landscape supports a variety of plant communities whose distribution corresponds to their topographic position. Topography controls snow accumulation and hence soil winter temperature, length of growing season and soil water availability. The research was conducted at the Teberda Biosphere Reserve (Northern Caucasus, Russia). The study sites were located at Mt. Malaya Khatipara (43°27'N, 41°42'E) between 2700 and 2750 m a.s.l. The investigated toposequence was representative of the soil and plant community associations in the alpine zone of the Teberda Reserve: the wind-exposed ridges and upper slopes are covered by low-productive alpine lichen heaths; intermediate topographic positions are occupied by the most productive grasslands and meadows; the slope bottom is occupied by low-productive snowbed community. Under intensive snow cover accumulation typical for many alpine ecosystems, the temperature of soil within winter makes nearby 0 °C, while in case of absence or thin snow cover, characteristic for a lichen heath, the temperature can fall to -10 °C. The influence of nitrogen source, low temperatures and soil drying on processes of nitrogen mineralization, nitrification and plant/microbial immobilization was studied in the field and laboratory incubation experiments. 15N labeled ammonium, nitrate, glycine and aspartic acid were injected in situ before growth of aboveground biomass into the soil of lichen heath to investigate how the different nitrogen sources was subsequently utilized and cycled in the ecosystem. We analyzed the distribution of 15N between plants, soil microorganisms and different soil nitrogen compounds during all growing season in order to reveal differences for separate nitrogen sources. We concluded that the soil microorganisms were more efficient than plants in nitrogen uptake (especially amino acids) under natural conditions. In the laboratory, fresh and dry-rewetted soils of different alpine ecosystems were incubated at

  15. Teberda valley runoff variability (AD 1850-2005) based on tree-ring reconstruction (Northern Caucasus, Russia)

    Seven tree-ring chronologies are used to reconstruct Teberda River (Northern Caucasus, Russia) smoothed runoff for May, July and August. Six chronologies were developed from Pinus sylvestris and one from Abies nordmanniana. Tree growth is significantly, but weakly, correlated with maximum temperatures (negatively) and relative humidity (positively) during summer. All possible combinations of seven predictors were tried to get the best result on the cross-validation. Two of three reconstructions showed high wavelet coherence with instrumental data on decadal timescales and were analysed for spectrum stability. Minima of moving trends at the end of the reconstructions along with weakening of decadal cycles may be a marker of significant change of Teberda River hydrological regime during the second half of the 20th century.

  16. Spectral and informational analysis of seismicity: An application to the 1996-2012 seismicity of the Northern Caucasus-Azerbaijan part of the greater Caucasus-Kopet Dag region

    Telesca, Luciano; Lovallo, Michele; Babayev, Gulam; Kadirov, Fakhraddin


    The time series analysis of seismic sequences needs proper methodologies that allow us to capture the main features of the time dynamics of earthquakes. Among these features, the identification of periodicities along with the quantification of their intensity represents an important task, concerning the detection of regular dynamical behaviours, with clear implications for earthquake prediction. In the present study, we applied three different methods to investigate the time dynamics of the seismic activity of the Northern Caucasus-Azerbaijan part of the Greater Caucasus-Kopet Dag region. We analysed the monthly number of earthquakes which occurred between 1996 and 2012 by means of: (i) the robust estimation of the periodogram, (ii) the singular spectrum analysis (SSA), and (iii) the Fisher-Shannon method. Two main significant periodicities are detected: 102 months and 20 months. The first corresponds actually to the long-term variation of the monthly seismic activity of the area, while the second represents the more intense cyclic component. Periodicities of 7 and 30 months are also identified, but with a lower intensity than the 20-month periodicity. The Fisher-Shannon method has revealed that the long-term variation of the series is also characterized by higher organization and lower degree of disorder. The present study shows how the application of methods from statistical mechanics could contribute to unveil dynamical features in seismicity.

  17. Megafans of the Northern Kalahari Basin

    Wilkinson, M. J.; Miller, R. McG.; Eckardt, F.; Kreslavsky, M. A.


    We identify eleven megafans (partial cones of fluvial sediment, >80 km radius) in the northern Kalahari Basin, using several criteria based on VIS and IR remotely sensed data and SRTM-based surface morphology reconstructions. Two other features meet fewer criteria of the form which we class as possible megafans. The northern Kalahari megafans are located in a 1700 km arc around the southern and eastern flanks of the Angola's Bié Plateau, from northern Namibia through northwest Botswana to western Zambia. Three lie in the Owambo subbasin centered on the Etosha Pan, three in the relatively small Okavango rift depression, and five in the Upper Zambezi basin. The population includes the well-known Okavango megafan (150 km), Namibia's Cubango megafan, the largest megafan in the region (350 km long), and the largest nested group (the five major contiguous megafans on the west slopes of the upper Zambezi Valley). We use new, SRTM-based topographic roughness data to discriminate various depositional surfaces within the flat N. Kalahari landscapes. We introduce the concepts of divide megafans, derived megafans, and fan-margin rivers. Conclusions. (i) Eleven megafan cones total an area of 190,000 sq km. (ii) Different controls on megafan size operate in the three component basins: in the Okavango rift structural controls become the prime constraint on megafan length by controlling basin dimensions. Megafans in the other les constricted basins appear to conform to classic relationships fan area, slope, and feeder-basin area. (iii) Active fans occupy the Okavango rift depression with one in the Owambo basin. The rest of the population are relict but recently active fans (surfaces are relict with respect to activity by the feeder river). (iv) Avulsive behavior of the formative river-axiomatic for the evolution of megafans-has resulted in repeated rearrangements of regional drainage, with likely effects in the study area well back into the Neogene. Divide megafans comprise the

  18. Subducted, detached, and torn slabs during early orogeny: evidence from deep earthquakes under the Greater Caucasus

    Mumladze, T.; Forte, A. M.; Cowgill, E.; Trexler, C.; Niemi, N. A.; Kellogg, L. H.; Yikilmaz, M.


    The Arabia-Eurasian collision is the second-largest active collisional orogen on Earth and provides a rare opportunity to investigate the role that pre-suturing tectonism plays in defining the deformational response of the upper plate to continental collision and suturing. The Greater Caucasus Mountains, which define the northern margin of the Arabia-Eurasia collision zone between the Black and Caspian seas, result from late Cenozoic closure of the Greater Caucasus basin, a Mesozoic back-arc basin that opened during northward subduction of Neotethys beneath the Lesser Caucasus island arc. However, both the extent to which the basin closed by subduction and its original width remain controversial. Many previous estimates suggest that the basin was very narrow and that no subduction occurred during the formation of the Greater Caucasus. However, newly compiled earthquake locations show that the central and eastern Greater Caucasus are underlain by a northeast-dipping subducted slab. We assembled the new catalog of earthquake locations by combining earthquake records from local networks in Georgia, Russia, and Azerbaijan with previously published data. Our dataset includes records from 3820 events with magnitudes M>2. Visualization of the final catalogue in an immersive visualization environment at the UC Davis Keck Center for Active Visualization in the Earth Sciences (KeckCAVES) provides a clear image of a northeast-dipping zone of seismicity beneath the Greater Caucasus, which we interpret as the remnant of a subducted slab. Beneath the central Greater Caucasus (45°E), the zone of seismicity extends to a depth of at least 158 km and dips to the northeast at ~40°. In contrast, beneath the western GC (i.e., west of 45°E) there is a pronounced lack of events below 25 km, which we infer to reflect slab breakoff. We also observe a gap in intermediate-depth seismicity (30 to 60 km) at the western end of the subducted slab beneath the central Greater Caucasus, which we

  19. Uranium deposits: northern Denver Julesburg basin, Colorado

    The Fox Hills Sandstone and the Laramie Formation (Upper Cretaceous) are the host rocks for uranium deposits in Weld County, northern Denver Julesburg basin, Colorado. The uranium deposits discovered in the Grover and Sand Creek areas occur in well-defined north--south trending channel sandstones of the Laramie Formation whereas the sandstone channel in the upper part of the Fox Hills Sandstone trends east--west. Mineralization was localized where the lithology was favorable for uranium accumulation. Exploration was guided by log interpretation methods similar to those proposed by Bruce Rubin for the Powder River basin, Wyoming, because alteration could not be readily identified in drilling samples. The uranium host rocks consist of medium- to fine-grained carbonaceous, feldspathic fluvial channel sandstones. The uranium deposits consist of simple to stacked roll fronts. Reserve estimates for the deposits are: (1) Grover 1,007,000 lbs with an average grade of 0.14 percent eU3O8,2) Sand Creek 154,000 lbs with an average grade of 0.08 percent eU3O8, and 3) The Pawnee deposit 1,060,000 lbs with an average grade of 0.07 percent eU3O8. The configuration of the geochemical cells in the Grover and Sand Creek sandstones indicate that uraniferous fluids moved northward whereas in the Pawnee sandstone of the Fox Hills uraniferous fluids moved southward. Precipitation of uranium in the frontal zone probably was caused by downdip migration of oxygcnated groundwater high in uranium content moving through a favorable highly carbonaceous and pyritic host sandstone

  20. Colloquium on Caucasus

    This document is the proceedings of a colloquium organized by the French senate on Caucasus. Caucasus encompasses three countries: Armenia, Azerbaijan and Georgia. In their presentations, the different participants stress on some particular political-economical aspects of this region: present day economic status, role in the development of central Asia, political stability of South Caucasus, influence of foreign countries (Russia, USA), relations with the European Union, the energy, road and rail paths, the stakes of Azerbaijan on the petroleum scene (hydrocarbons production and transit), hydrocarbons exploitation in Azerbaijan (regional cooperation, foreign investments, profits), experience of foreign companies working in Caucasus countries (beverage industry), juridical framework of investments made in Caucasus countries, business reality in these countries. (J.S.)

  1. Aklimaite, Ca4[Si2O5(OH)2](OH)4 · 5H2O, a new natural hydrosilicate from Mount Lakargi, the Northern Caucasus, Russia

    Zadov, A. E.; Pekov, I. V.; Zubkova, N. V.; Gazeev, V. M.; Chukanov, N. V.; Yapaskurt, V. O.; Kartasheov, P. M.; Galuskin, E. V.; Galuskina, I. O.; Pertsev, N. N.; Gurbanov, A. G.; Pushcharovsky, D. Yu.


    A new mineral aklimaite, Ca4[Si2O5(OH)2](OH)4 · 5H2O, has been found near Mount Lakargi, Upper Chegem caldera, Kabardino-Balkaria, the Northern Caucasus, Russia, in the skarnified limestone xenolith in ignimbrite. This hydrothermal mineral occurs in a cavity of altered larnite skarn and is associated with larnite, calcium humite-group members, hydrogarnets, bultfonteinite, afwillite, and ettringite. Aklimaite forms transparent, colorless (or occasionally with pinkish tint) columnar or lath-shaped crystals up 3 × 0.1 × 0.01 mm in size, flattened on {001} and elongated along {010}; they are combined in spherulites. The luster is vitreous; the cleavage parallel to the {001} is perfect. D calc = 2.274 g/cm3. The Mohs' hardness is 3-4. Aklimaite is optically biaxial, negative, 2 V meas > 70°, 2 V calc = 78°, α = 1.548(2), β = 1.551(3), γ = 1.553(2). The IR and Raman spectra are given. The chemical composition (wt %, electron microprobe) is as follows: 0.06 Na2O, 0.02 K2O, 45.39 CaO, 0.01 MnO, 0.02 FeO, 24.23 SiO2, 0.04 SO3, 3.22 F, 27.40 H2O(calc.), -1.36 -O=F2; the total is 99.03. The empirical formula calculated on the basis of 2Si apfu with O + OH + F = 16 is as follows: (Ca4.02Na0.01)Σ4.03[Si2.00O5.07(OH)1.93][(OH)3.16F0.84] Σ4.00 · 5H2O. The mineral is monoclinic, space group C2/ m, a = 16.907(5), b = 3.6528(8), c = 13.068(4) Å, β = 117.25(4)·, V= 717.5(4) Å3, Z = 2. Aklimaite is representative of the new structural type, the sorosilicate with disilicate groups [Si2O5(OH)2]. The strongest reflections in the X-ray powder patterns [ d, Å ( hkl)] are: 11.64(100)(001), 2.948(32)(310, 203), 3.073(20) (, ), 2.320(12)(005, 510), 2.901 (11)(004), 8.30(10). The type specimen is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow.

  2. Geomorphological characterization of endorheic basins in northern Chile

    Dorsaz, J.; Gironas, J. A.; Escauriaza, C. R.; Rinaldo, A.


    Quantitative geomorphology regroups a large number of interesting tools to characterize natural basins across scales. The application of these tools to several river basins allows the description and comparison of geomorphological properties at different spatial scales as oppose to more traditional descriptors that are typically applied at a single scale, meaning the catchment scale. Most of the recent research using these quantitative geomorphological tools has focused on open catchments and no specific attention has been given to endorheic basins, and the possibility of having particular features that distinguish them from exorheic catchments. The main objective of our study is to characterize endorheic basins and investigate whether these special geomorphological features can be identified. Because scaling invariance is a widely observed and relatively well quantified property of open basins, it provides a suitable tool to characterize differences between the geomorphology of closed and open basins. Our investigation focuses on three closed basins located in northern Chile which describe well the diversity in the geomorphology and geology of this arid region. Results show that endhoreic basins exhibit different slope-area and flow paths sinuosity regimes compared to those observed in open basins. These differences are in agreement with the particular self-similar behavior across spatial scales of the Euclidean length of subcatchments, as well as the Hack's law and Horton's ratios. These regimes imply different physical processes inside the channel network regardless of the basin area, and they seem to be related to the endorheic character of these basins. The analysis of the probability density functions of contributing areas and lengths to the lower region shows that the hypothesis of self-similarity can also be applied to closed basins. Theoretical expressions for these distributions were derived and validated by the data. Future research will focus on (1

  3. Northern Rivers Basins human health monitoring program : report

    Gabos, S. [Alberta Health, Edmonton, AB (Canada). Health Surveillance


    The Northern River Basins Human Health Monitoring Program was established in 1994 to investigate the possible relationships between various environmental risk factors and the health of northern residents in the province. This report presents the initial analysis of the health program and examines the differences in health outcomes across the province and compares the Northern Rivers Basin Study (NRBS) area with the other areas of the province. A series of maps and graphs showed the prevalence of certain diseases and disorders within the Peace and Athabasca river basins. The focus of the report was on reproductive health, congenital anomalies, respiratory ailments, circulatory diseases, gastrointestinal disorders, endocrine and metabolic disorders, and neurocognitive disorders. The study showed that compared to other areas of the province, the NRBS area had higher incidences of endometriosis, selected congenital anomalies, bronchitis, pneumonia, peptic ulcers and epilepsy. There were three potential exposure pathways to environmental contaminants. These were through ingestion of water or food, inhalation of air and through dermal exposure. refs., tabs., figs.

  4. Helminth parasites of freshwater fishes, Nazas River basin, northern Mexico

    León, G. Pérez-Ponce


    Full Text Available This paper represents the first study of the helminth parasites of freshwater fishes from the Nazas River basinin northern Mexico. Between July 2005 and December 2008, 906 individual fish were collected and examined for helminthparasites in 23 localities along the river basin. Twenty-three species of fish were examined as a part of this inventory work.In total, 41 helminth species were identified: 19 monogeneans, 10 digeneans, seven cestodes, one acanthocephalan, andfour nematodes. The biogeographical implications of our findings are briefly discussed.

  5. Three-dimensional seismo-tectonics in the Po Valley basin, Northern Italy

    Turrini, Claudio; Angeloni, Pamela; Lacombe, Olivier; Ponton, Maurizio; Roure, François


    The Po Valley (Northern Italy) is a composite foreland-foredeep basin caught in between the Southern Alps and Northern Apennine mountain belts. By integrating the 3D structural model of the region with the public earthquake dataset, the seismo-tectonics of the basin is shown at different scales of o

  6. The characteristics of ginger-like rock and its geological significance in Northern Zhungeer basin

    The author studies the characteristics of ginger-like stratum and its genesis in northern Zhungeer basin. There are many ginger-like strata of Tertiary-Quaternary exist in northern Zhungeer basin. It shows a good prospect for the formation of Tertiary sandstone type Uranium deposit which can be leached in-situ


    Alizade, Zakhida


    The author uses a vast amount of factual material to reveal the essence of czarist Russia’s colonial imperial policy toward the Muslims of the Caucasus, and Northern Azerbaijan in particular, when the area was finally conquered in the early 19th century. This discriminatory policy was acutely felt in all spheres of life; the Azeris, in particular, were deprived of many political, civil, and religious rights. Russia’s reforms in the area deprived Northern Azerbaijan of its previous administrat...

  8. Cenozoic foreland-basin evolution in the northern Andes : insights from thermochronology and basin analysis in the Eastern Cordillera, Colombia

    Parra, Mauricio


    The modern foreland basin straddling the eastern margin of the Andean orogen is the prime example of a retro-arc foreland basin system adjacent to a subduction orogen. While widely studied in the central and southern Andes, the spatial and temporal evolution of the Cenozoic foreland basin system in the northern Andes has received considerably less attention. This is in part due to the complex geodynamic boundary conditions, such as the oblique subduction and accretion of the Caribbean plates ...

  9. Regional Fluid Flow and Basin Modeling in Northern Alaska

    Kelley, Karen D., (Edited By)


    INTRODUCTION The foothills of the Brooks Range contain an enormous accumulation of zinc (Zn) in the form of zinc sulfide and barium (Ba) in the form of barite in Carboniferous shale, chert, and mudstone. Most of the resources and reserves of Zn occur in the Red Dog deposit and others in the Red Dog district; these resources and reserves surpass those of most deposits worldwide in terms of size and grade. In addition to zinc and lead sulfides (which contain silver, Ag) and barite, correlative strata host phosphate deposits. Furthermore, prolific hydrocarbon source rocks of Carboniferous and Triassic to Early Jurassic age generated considerable amounts of petroleum that may have contributed to the world-class petroleum resources of the North Slope. Deposits of Zn-Pb-Ag or barite as large as those in the Brooks Range are very rare on a global basis and, accordingly, multiple coincident favorable factors must be invoked to explain their origins. To improve our understanding of these factors and to contribute to more effective assessments of resources in sedimentary basins of northern Alaska and throughout the world, the Mineral Resources Program and the Energy Resources Program of the U.S. Geological Survey (USGS) initiated a project that was aimed at understanding the petroleum maturation and mineralization history of parts of the Brooks Range that were previously poorly characterized. The project, titled ?Regional Fluid Flow and Basin Modeling in Northern Alaska,? was undertaken in collaboration with industry, academia, and other government agencies. This Circular contains papers that describe the results of the recently completed project. The studies that are highlighted in these papers have led to a better understanding of the following: *The complex sedimentary facies relationships and depositional settings and the geochemistry of the sedimentary rocks that host the deposits (sections 2 and 3). *The factors responsible for formation of the barite and zinc deposits

  10. Tectonic evolution of Tethyan tectonic field, formation of Northern Margin basin and explorative perspective of natural gas in Tarim Basin


    Analyzing the characteristics of the Tethyan tectonic field, the authors think that the Tethyan tectonic field underwent three evolutional stages: closing of Paleo-Tethys and rifting of Neo-Tethys from early Permian to late Triassic, subduction of Neo-Tethys and collision between the Indian plate and the Eurasia plate from Jurassic to early of low Tertiary, and collision between the Arab plate and the Eurasia plate and the A-type subduction of Indian plate from late of low Tertiary to the present. Combining the evolution of the Tethyan orogenic belt with the characteristics of the Northern Margin basin, it is suggested that the sedimentary and tectonic characteristics and types of the Northern Mar-gin basin are controlled by the formation and evolution of the Tethyan orogenic belt and the ingression of Tethys. The evolution of Northern Margin basin can be divided into three development stages: back-arc foreland basin from late Permian to Triassic, the back-arc fault subsidence and depression from Jurassic to the early of low Tertiary, and the reactive foreland basin from the late of low Tertiary to the present. The Northern Margin basin in the Tethyan tectonic field is an important region for natural gas accumulation, and the Tarim Basin is a part of this region.

  11. Linking basin evolution to plate tectonic processes in (northern) Africa

    Gravråk, Mariann


    Several sedimentary basins in Africa are classified as intracratonic basins, but no conclusive formation mechanism has been identified for these basin types. Tectonic subsidence curves may help in unraveling formation mechanisms or identify tectonic forcing for these basins. This thesis presents and analyses basin subsidence curves for basins in the interior of Africa and near its passive margins. A backstripping program has been written to solve the backstripping equations needed to make the...

  12. Digital assessment of northern and central Appalachian basin coals

    Ruppert, L.F.; Tewalt, S.J.; Braff, L.J.; Wallack, R.N. [US Geological Survey National Center, Reston, VA (US)


    The US Geological Survey (USGS) is currently conducting a coal resource assessment of the coalbeds and zones that are projected to provide the bulk of the nation's resources for the next few decades. The Pittsburgh and Upper Freeport coals are the first two beds in the northern and central Appalachian basin region to undergo fully digital coal assessments. The bed-specific assessments are being carried out in partnership with the state geologic surveys of West Virginia, Ohio, Pennsylvania and Maryland. Comprehensive stratigraphic and geochemical data-bases have been developed for both of the beds. The extent of the bed with mined areas, structure contour, isopach, and overburden thickness maps for the Pittsburgh coal bed have been realised as USGS open-file reports. The articles includes several detailed maps showing the export of the Pittsburgh coalbed, ash yield, sulphur contents and calorific value of the coal by county, structure contours, overburden thickness and isopac lines. 10 figs., 2 tabs.

  13. Early Mesozoic history of the Black-Sea - Caucasus area

    Kazmin, V.G. (Institute of Oceanology, Moscow (USSR))


    Marginal basins with ocean crust existed in the Black Sea area in Triassic time behind a volcanic arc built on top of the Hercynian basement of Pontides. The eastern extension of the arc was in the fore-Caucasus. Triassic sediments and volcanics, formed in forearc basins, can be traced from the southern slope of the Great Caucasus (Svanetia) to the Karakaya belt of Turkey. These sediments were deformed at the end of the Triassic when terranes derived from Gondwana collided with the active margin of Paleotethys. In Svanetia a succession of middle Paleozoic clastics (the Dizi series) deposited at the base of the north-facing continental slope, presumably on the passive margin of Gondwana. The Dizi series is either an independent terrane or forms a western extension of Iran, which collided with Eurasia at the same time. Displacement of the subduction zone to the south of the accreted terranes was accompanied by a major episode of extension on the active margin in Early Jurassic time; the marginal sea of the Great Caucasus and the intra-Pontide basin in Turkey were opened. In the late Middle Jurassic, Pontides collided with Crimea, closing the Triassic proto-Black Sea. Immediately after collision, continental rifting commenced, once again separating Pontides from Eurasia and manifesting the birth of the Black Sea basin. Oceanic crust began to grow in the latter in Senonian time.

  14. Caucasus Geopolitics: Modern Trends Conflicts and Development

    Svetlana V. Petrova


    Full Text Available The article studies major trends of Caucasus geopolitical situation development in terms of modern global politics, indicates major parties, settling conflicts in the region and their immediate interests in the Caucasus.

  15. Fluid flow in the northern Broad Fourteens Basin during Late Cretaceous inversion

    Oude Essink, Gualbert


    A basin-scale hydrogeological study of the inverted northern Broad Fourteens Basin, Netherlands offshore, has resulted in a reconstruction of geological evolution, an estimate of Late Cretaceous topography and model scenarios of syn-inversion meteoric water infiltration. This study was performed in

  16. Deep crustal structure of the Adare and Northern Basins, Ross Sea, Antarctica, from sonobuoy data

    Selvans, M. M.; Stock, J. M.; Clayton, R. W.; Cande, S.; Granot, R.


    Extension associated with ultraslow seafloor spreading within the Adare Basin, in oceanic crust just north of the continental shelf in the Ross Sea, Antarctica, extended south into the Northern Basin. Magnetic and gravity anomaly data suggest continuity of crustal structure across the continental shelf break that separates the Adare and Northern Basins. We use sonobuoy refraction data and multi-channel seismic (MCS) reflection data collected during research cruise NBP0701, including 71 new sonobuoy records, to provide constraints on crustal structure in the Adare and Northern Basins. Adjacent 1D sonobuoy profiles along several MCS lines reveal deep crustal structure in the vicinity of the continental shelf break, and agree with additional sonobuoy data that document fast crustal velocities (6000-8000 m/s) at shallow depths (1-6 km below sea level) from the Adare Basin to the continental shelf, a structure consistent with that of other ultraslow-spread crust. Our determination of crustal structure in the Northern Basin only extends through sedimentary rock to the basement rock, and so cannot help to distinguish between different hypotheses for formation of the basin.

  17. Paleogene palaeogeography and basin evolution of the Western Carpathians, Northern Pannonian domain and adjoining areas

    Kováč, Michal; Plašienka, Dušan; Soták, Ján; Vojtko, Rastislav; Oszczypko, Nestor; Less, György; Ćosović, Vlasta; Fügenschuh, Bernhard; Králiková, Silvia


    The data about the Paleogene basin evolution, palaeogeography, and geodynamics of the Western Carpathian and Northern Pannonian domains are summarized, re-evaluated, supplemented, and newly interpreted. The presented concept is illustrated by a series of palinspastic and palaeotopographic maps. The Paleogene development of external Carpathian zones reflects gradual subduction of several oceanic realms (Vahic, Iňačovce-Kričevo, Szolnok, Magura, and Silesian-Krosno) and growth of the orogenic accretionary wedge (Pieniny Klippen Belt, Iňačovce-Kričevo Unit, Szolnok Belt, and Outer Carpathian Flysch Belt). Evolution of the Central Western Carpathians is characterized by the Paleocene-Early Eocene opening of several wedge-top basins at the accretionary wedge tip, controlled by changing compressional, strike-slip, and extensional tectonic regimes. During the Lutetian, the diverging translations of the northward moving Eastern Alpine and north-east to eastward shifted Western Carpathian segment generated crustal stretching at the Alpine-Carpathian junction with foundation of relatively deep basins. These basins enabled a marine connection between the Magura oceanic realm and the Northern Pannonian domain, and later also with the Dinaridic foredeep. Afterwards, the Late Eocene compression brought about uplift and exhumation of the basement complexes at the Alpine-Carpathian junction. Simultaneously, the eastern margin of the stretched Central Western Carpathians underwent disintegration, followed by opening of a fore-arc basin - the Central Carpathian Paleogene Basin. In the Northern Hungarian Paleogene retro-arc basin, turbidites covered a carbonate platform in the same time. During the Early Oligocene, the rock uplift of the Alpine-Carpathian junction area continued and the Mesozoic sequences of the Danube Basin basement were removed, along with a large part of the Eocene Hungarian Paleogene Basin fill, while the retro-arc basin depocentres migrated toward the east

  18. Cenozoic evolution of the northwestern Salar de Atacama Basin, northern Chile

    Pananont, P.; Mpodozis, C.; Blanco, N.; Jordan, T. E.; Brown, L. D.


    Since 90 Ma, the nonmarine Salar de Atacama Basin has been the largest, deepest, and most persistent sedimentary basin of northern Chile. Integration of 200 km of two-dimensional seismic reflection data with surface geological data clarifies Oligocene and Neogene evolution of the northern part of the basin. A normal fault with 6 ± 1 km of vertical separation controlled the western boundary of the basin during the accumulation of the Oligocene-lower Miocene Paciencia Group. The combination of this structure, a similar one in the Calama Basin, and regional structural data suggests that localized extension played an important role within a tectonic environment dominated by margin-perpendicular compression and margin-parallel strike-slip deformation. Seismic data substantiate the surface interpretation that much of the Cordillera de la Sal ridge resulted from diapiric flow of the Paciencia Group. Diapiric flow initiated during the late early Miocene or middle Miocene, associated with a deep reverse fault.

  19. Meso-Cenozoic basin evolution in northern Korean Peninsula

    PAK Hyon Uk; LYANG To Jun; LIU Yongjiang; HYON Yun Su; KIM Gyong Chol


    In the Korean Peninsula the Meso-Cenozoic basins were mainly formed due to fault block and block movement. The Mesozoic fracture structures correspond basically to modern large rivers in direction. Such faults were usually developed to rift and formed lake-type tectonic basin, such as the Amrokgang-, Taedonggang-, Ryesonggang-, Hochongang-, Jangphari-, Susongchon-, Pujon-, and Nampho basins. The Mesozoic strata are considered to be divided into the Lower Jurassic Taedong System, Upper Jurassic Jasong System, Upper Jurassic- -early Lower Cretaceous Taebo System, and the Upper Cretaceous- -Paleocene (Chonjaebong, Hongwon, Jaedok Series). The Cenozoic block movement succeeded the Mesozoic fault block movement. The Kilju-Myongchon Graben and Tumangang Basin, etc, are the basins related to the fault zones developed from the Oligocene to Miocene. In addition, the Tertiary basins were formed in many areas in the Miocene (e.g. Sinhung, Oro, Hamhung, Yonghung, Anbyon, Cholwon, etc). The Cenozoic sedimentation occurred mainly from the late Oligocene to Miocene. The Kilju-Myongchon Graben was the fore deep connected to the sea and the basins inclined in the Chugaryong Fault Zone are intramountain basins. Therefore, coal-bearing beds and clastic rocks in the intramountain basins and rare marine strata and terrigenous clastic rocks are main sedimentary sequences in the Cenozoic.

  20. Decoupling of modern shortening rates, climate, and topography in the Caucasus

    Forte, Adam M.; Whipple, Kelin X.; Bookhagen, Bodo; Rossi, Matthew W.


    The Greater and Lesser Caucasus mountains and their associated foreland basins contain similar rock types, experience a similar two-fold, along-strike variation in mean annual precipitation, and were affected by extreme base-level drops of the neighboring Caspian Sea. However, the two Caucasus ranges are characterized by decidedly different tectonic regimes and rates of deformation that are subject to moderate (less than an order of magnitude) gradients in climate, and thus allow for a unique opportunity to isolate the effects of climate and tectonics in the evolution of topography within active orogens. There is an apparent disconnect between modern climate, shortening rates, and topography of both the Greater Caucasus and Lesser Caucasus which exhibit remarkably similar topography along-strike despite the gradients in forcing. By combining multiple datasets, we examine plausible causes for this disconnect by presenting a detailed analysis of the topography of both ranges utilizing established relationships between catchment-mean erosion rates and topography (local relief, hillslope gradients, and channel steepness) and combining it with a synthesis of previously published low-temperature thermochronologic data. Modern climate of the Caucasus region is assessed through an analysis of remotely-sensed data (TRMM and MODIS) and historical streamflow data. Because along-strike variation in either erosional efficiency or thickness of accreted material fail to explain our observations, we suggest that the topography of both the western Lesser and Greater Caucasus are partially supported by different geodynamic forces. In the western Lesser Caucasus, high relief portions of the landscape likely reflect uplift related to ongoing mantle lithosphere delamination beneath the neighboring East Anatolian Plateau. In the Greater Caucasus, maintenance of high topography in the western portion of the range despite extremely low (structure of either range.

  1. Multiple Refuge Bat Inventory: Great Basin & Great Northern LCC

    US Fish and Wildlife Service, Department of the Interior — This was a cooperative project between the Upper Columbia Basin Network (UCBN) of the National Park Service I&M Program, USFWS Region 1 I&M Program (R1...

  2. Petroleum potential of the northern Sinu-San Jacinto Basin, Colombia: an integrated petroleum system and basin modeling approach

    Nino, Christian H.; Goncalves, Felix T.T.; Bedregal, Ricardo P. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE). Lab. de Modelagem de Bacias (LAB2M); Azevedo, Debora A. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Quimica; Landau, Luis [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE). Lab. de Metodos Computacionais em Engenharia (LAMCE)


    The northern Sinu-San Jacinto basin, located in the northwestern corner of South America (Colombia), belongs to the accretionary prism that resulted from the collision and subduction of the Caribbean plate under the South America plate. Despite all the previous exploratory efforts, solely a few small sub-commercial oil and gas accumulation have been found up to now. The geological and geochemical information acquired by different companies during the lasts decades was integrated with new geochemical analysis and basin modeling to characterize the petroleum systems, to reconstruct the hydrocarbon charge history in the study area and to better assess the exploratory risk. (author)

  3. Deep seismic structure of the Atacama basin, northern Chile

    Schurr, B.; Rietbrock, A.


    The Atacama basin is a prominent morphological anomaly in the Central Andean forearc. 3D seismic structure beneath the depression and its surroundings has been determined from local earthquake tomography. Depth maps of P-wave velocity and attenuation (1/Qp) through the lithosphere reveal a rheologically strong (high Qp and vp) lithospheric block beneath the basin, surrounded by weak regions (low Qp and vp) beneath Pre- and Western Cordilleras. The anomalous lithospheric structure appears to bar hot asthenospheric mantle from penetrating trenchward, and hence causes the volcanic front to be deflected by the Salar de Atacama basin. The cold block may also influence the thermal structure of the subducted slab causing reduced Benioff seismicity and less hydration of mantle rocks evident from reduced vp/vs ratios. Seismic data are hard to reconcile with extension and lithospheric thinning as a mechanism for subsidence of the basin. Instead, high strength of the Atacama lithospheric block may contribute to basin formation by focussing deformation and uplift along the block's weak edges.

  4. Low palaeoelevation of the northern Lhasa terrane during late Eocene: Fossil foraminifera and stable isotope evidence from the Gerze Basin

    Yi Wei; Kexin Zhang; Garzione, Carmala N.; Yadong Xu; Bowen Song; Junliang Ji


    The Lhasa terrane is a key region for understanding the paleoelevation of the southern Tibetan Plateau after India-Asia collision. The Gerze Basin, located in the northern part of the Lhasa terrane, is a shortening-related basin. We discovered Lagena laevis (Bandy) fossils in upper Eocene strata of the Gerze Basin. This type of foraminifera is associated with lagoon and estuarine environments, indicating that the northern part of the Lhasa terrane was near sea level during the late Eocene. We...

  5. Discussion on the characteristics of Meso-Cenozoic U-productive basins in northern China and their prospecting direction

    Based on the study of sedimentary evolution characteristics of main sedimentary basins and combined with characteristics of known uranium-productive basins in northern China, and the analysis on airborne geophysical survey data, the principles for selecting prospecting and target area have been set up. And the prospecting direction for uranium in Meso-Cenozoic basins of northern China has been proposed through a preliminary analysis. (authors)

  6. Potential Inundation Hazards in the Taipei Basin Induced by Reactivation of the Shanchiao Fault in Northern Taiwan

    Jihn-Sung Lai; Chun-Ying Chiu; Hsiang-Kuan Chang; Jyr-Ching Hu; and Yih-Chi Tan


    The Shanchiao fault, located to the west of the Taipei Basin in northern Taiwan, is a highly active normal fault that has a left-slip component and fault length of over 40 km. We suggest that the Shanchiao fault still has the ability to induce coseismic subsidence in the Taipei Basin under present extensional regime of northern Taiwan. In order to characterize the coseismic ground deformation and assess the potential inundation hazards in Taipei Basin, we estimate surface displacements using ...

  7. The U.S. Geological Survey`s National Coal Resource Assessment: The Northern and Central Appalachian Basin

    Ruppert, L.; Bragg, L.; Tewalt, S. [Geological Survey, Reston, VA (United States)


    The US Geological Survey (USGS) Energy Resource Surveys Program is currently conducting a five-year National Coal Resource Assessment project. Primary focus is on the quality and quantity of top-producing coal beds and coal zones in five of the nine major coal producing regions in the US. These regions include the (1) Northern and Central Appalachian Basin, (2) Gulf Coastal Plain, (3) Illinois Basin, (4) Colorado Plateau, and (5) Powder River Basin and Northern Great Plains.

  8. Tectonoestratigraphic and Thermal Models of the Tiburon and Wagner Basins, northern Gulf of California Rift System

    Contreras, J.; Ramirez Zerpa, N. A.; Negrete-Aranda, R.


    The northern Gulf of California Rift System consist sofa series faults that accommodate both normal and strike-slip motion. The faults formed a series of half-greens filled with more than 7 km of siliciclastic suc­cessions. Here, we present tectonostratigraphic and heat flow models for the Tiburón basin, in the southern part of the system, and the Wag­ner basin in the north. The models are constrained by two-dimensional seis­mic lines and by two deep boreholes drilled by PEMEX­-PEP. Analysis of the seismic lines and models' results show that: (i) subsidence of the basins is controlled by high-angle normal faults and by flow of the lower crust, (ii) basins share a common history, and (iii) there are significant differences in the way brittle strain was partitioned in the basins, a feature frequently observed in rift basins. On one hand, the bounding faults of the Tiburón basin have a nested geometry and became active following a west-to-east sequence of activation. The Tiburon half-graben was formed by two pulses of fault activity. One took place during the protogulf extensional phase in the Miocene and the other during the opening of Gulf of California in the Pleistocene. On the other hand, the Wagner basin is the result of two fault generations. During the late-to middle Miocene, the west-dipping Cerro Prieto and San Felipe faults formed a domino array. Then, during the Pleistocene the Consag and Wagner faults dissected the hanging-wall of the Cerro Prieto fault forming the modern Wagner basin. Thermal modeling of the deep borehole temperatures suggests that the heat flow in these basins in the order of 110 mW/m2 which is in agreement with superficial heat flow measurements in the northern Gulf of California Rift System.

  9. Adaptation tot changing water resources in the Ganges basin, northern India

    Moors, E.J.; Groot, A.M.E.; Biemans, H.; Terwisscha van Scheltinga, C.T.H.M.; Siderius, C.; Stoffel, M.


    An ensemble of regional climate model (RCM) runs from the EU HighNoon project are used to project future air temperatures and precipitation on a 25 km grid for the Ganges basin in northern India, with a view to assessing impact of climate change on water resources and determining what multi-sector a

  10. The mechanics of continental extension in Qiongdongnan Basin, northern South China Sea

    Zhao, Zhongxian; Sun, Zhen; Wang, Zhenfeng; Sun, Zhipeng


    Located in the intersection of NE-trended rifted margin of South China Sea (SCS) and NW-oriented Ailao Shan-Red River Shear Zone (RRSZ), Qiongdongnan Basin shows significant differences in geological features from west to east, indicating different mechanics of continental extension. Based on the dense and updated multichannel seismic profiles, we disclose the characteristics of the remnant crystalline crust. Besides, we analyze the basin structures, calculate the stretching factors of upper and whole crust, and compute the syn-rift and post-rift unloaded tectonic subsidence along three selected transects in the west, middle and east of Qiongdongnan Basin. The crust thickness is 22 km on the northern and southern parts of Qiongdongnan Basin and thins gradually towards the central depression with two extremely thinned domains (factors of crust are 1.5-2 on both sides and increase remarkably towards the central depression (β > 2) with two extremely stretched domains (β > 9), of which one is in Ledong Sag in the west and another is in Baodao and Changchang Sags in the east. However, the mechanics of continental extension vary significantly from west to east. The simple shear dominates in the west, the pure shear dominates in the east, and it is intermediate between the two end members of simple shear and pure shear in the middle of Qiongdongnan Basin. The simple shear in the west of Qiongdongnan Basin is probably controlled by the left-lateral movement of RRSZ. The pure shear in the east is probably related to the Cenozoic rifting along the northern continental margin of SCS. The transitional zone in the middle of Qiongdongnan Basin is possibly the combined results of the left-lateral movement of RRSZ and the Cenozoic rifting along the northern continental margin of SCS.

  11. A decision support tool for basin irrigation in northern Nigeria

    Olumuyiwa S. Asaolu


    Full Text Available Inadequate rainfall, water resources scarcity and attendant food security-related problems have made irrigation technology a necessity. This work presents the development of a decision support system for solving surface irrigation design problems in northern Nigeria. The arid northern states affected by desert encroachment constitute a good candidate and their climatological data was obtained from the Nigerian Metrological Agency. The interactive system was defined in terms of inputs and outputs. The inputs were properties of soil, surface irrigation method and climate. The outputs were mainly the quantity of water application, scheduling pattern, possible design configuration, advance time, cut-off time, application rate, and water use efficiency. The FAO Penman-Monteith equation was used to estimate evapotranspiration values of major crops grown in Nigeria. Mathematical models outlined by Walker and Skogerboe were adapted, and heuristics applied in determining the best configuration that achieves optimum water application efficiency. We encoded the knowledge base using Matlab® software. The application was successfully used for the modification of a farm irrigation scheme in Kaduna state. This indicates that the adoption of new technologies for irrigation design issues could enhance agricultural productivity in northern Nigeria.

  12. Colloquium on Caucasus; Colloque sur le Caucase



    This document is the proceedings of a colloquium organized by the French senate on Caucasus. Caucasus encompasses three countries: Armenia, Azerbaijan and Georgia. In their presentations, the different participants stress on some particular political-economical aspects of this region: present day economic status, role in the development of central Asia, political stability of South Caucasus, influence of foreign countries (Russia, USA), relations with the European Union, the energy, road and rail paths, the stakes of Azerbaijan on the petroleum scene (hydrocarbons production and transit), hydrocarbons exploitation in Azerbaijan (regional cooperation, foreign investments, profits), experience of foreign companies working in Caucasus countries (beverage industry), juridical framework of investments made in Caucasus countries, business reality in these countries. (J.S.)

  13. Evidence for bloc rotation tectonics in the seismic Cheliff basin (northern Algeria) from paleomagnetic investigations

    El-M. Derder, Mohamed; Henry, Bernard; Amenna, Mohamed; Bayou, Boualem; Maouche, Said; Besse, Jean; Ayache, Mohamed; Abtout, Abdeslam


    The seismic activity in the Western Mediterranean area is mainly concentrated in northern Africa, particularly in northern Algeria, as it was shown by the 21 May 2003 Boumerdes and the 10 October 1980 El Asnam earthquakes (of moment magnitudes Mw =6.9, and Ms= 7.3 respectively), which were among the strongest recent ones recorded in the western Mediterranean area. This seismicity is due to the convergence between Africa and Eurasia plates since at least the Oligocene. This convergence involves a transpression tectonic with N-S to NNW-SSE direction of shortening, which is expressed by active deformations along the boundary of these two plates. In Algeria, the seismicity is focused in a coastal zone (the Tell Atlas) in the northern part of the country. Active structures define there NE-SW trending folds and NE-SW sinistral transpressive faults, which affect the intermountain and coastal basins of Neogene to Quaternary age (e.g. " Cheliff "basin, " Mitidja "basin). These reverse faults are coupled with NW-SE to E-W trending strike-slip deep faults. The active deformation in northern Algeria could thus be explained by a kinematic model of bloc rotation: the transpression tectonics with NNW-SSE direction of convergence defines NE-SW oriented blocs, which have been possibly subjected to clockwise rotation. The aim of this study is to look for such blocks rotation in the "Cheliff" basin (northern Algeria), by using the paleomagnetic tool. A paleomagnetic study has been thus conducted on the midlle Miocene, Tortonian, Messinian and Pliocene sedimentary rocks cropping out on the eastern part of this basin. The study is still in progress, but despite the very weak intensity of the Natural Remanent Magnetization (NRM) measured on the samples, and the frequently observed magnetization instability during the thermal demagnetization, the preliminary results show that clockwise rotations have affected different sites of the studied area. The magnitude of these rotations varies

  14. Structure and seismic stratigraphy of deep Tertiary basins in the northern Aegean Sea

    Beniest, Anouk; Brun, Jean-Pierre; Smit, Jeroen; Deschamps, Rémy; Hamon, Youri; Crombez, Vincent; Gorini, Christian


    Whereas active basin formation in the Aegean Sea is illustrated by seafloor bathymetry, the sedimentary and tectonic history of Tertiary basins is poorly known as existing offshore industrial seismic and well-log data are not easily accessible. We studied the evolution of the northern Aegean Sea with a focus on the North Aegean Trough and the Northern Skyros Basin, which are amongst the deepest basins of the northern Aegean domain. Structural and seismic stratigraphic interpretation of a 2D seismic dataset retrieved in the 1970's is combined with the well-investigated records of the onshore deep basins of northern Greece and Western Turkey. A general seismic signature chart was established using onshore basin stratigraphy and poorly-constrained well data. The studied domain shows two sharp unconformities that correspond to the Eocene-Oligocene transition and the Miocene-Pliocene shift, respectively. These transitions were then used as pillars for a more detailed structural and seismic stratigraphic interpretation. A NW-SE trending seismic line that cross-cuts the southern part of the NE-SW-trending North Aegean Through displays the main features that are observed in the area: 1) an overall basin geometry that is rather symmetrical; 2) pre-Pliocene units affected by steep normal faults; 3) a rather constant thickness of Oligocene sediments that define a depocenter with an apparent NW-SE orientation; 4) an ablation of Miocene sediments by erosion, likely related to the Messinian Salinity Crises (MSC); (5) thick deltaic/turbiditic deposits in the NE-SW oriented central through of Neogene age; 6) trans-tensional growth patterns in Pliocene and Quaternary sediments that combine NE-SW steeply dipping fault zones, more likely corresponding to strike-slip corridors, and E-W-trending normal faults. The evidence listed above suggest that, in the northern Aegean Sea, (1) extension started at the latest during the Late Eocene/Early Oligocene (data quality does not allow for a

  15. Estimating flows in ungauged river basins in northern Mozambique

    Minihane, M.


    In many regions across the globe, there are limited streamflow observations and therefore limited knowledge of availability of surface water resources. In many cases, these rivers lie in countries that would benefit from economic development and improved access to water and sanitation services, both of which are linked to water resources. Additional information about streamflow in these watersheds is critical to water resources planning and economic development strategies. In southeastern Africa, the remote Rovuma River lies on the border between Mozambique and Tanzania. There are limited historic measurements in the main tributary and no recent observations. Improved knowledge of the water resource availability and inter-annual variability of the Rovuma River will enhance transboundary river basin management discussions for this river basin. While major rivers farther south in the country are more closely monitored, those in the north have gauging stations with only scattered observations and have not been active since the early 1980's. Reliable estimates of historic conditions are fundamental to water resources planning. This work aims to provide estimates in these rivers and to quantify uncertainty and bounds on those estimates. A combination of methods is used to estimate historic flows: simple index gauge methods such as the drainage area ratio method and mean flow ratio method, a statistical regression method, a combination of an index gauge method and global gridded runoff data, and a hydrological model. These results are compared to in-situ streamflow estimates based on stage measurements and rating curves for the basins and time frames for which data is available. The evaluation of the methods is based on an efficiency ratio, bias, and representation of seasonality and inter-annual variability. Use of gridded global datasets, either with the mean flow ratio method or a hydrological model, appears to provide improved estimates over use of local observations

  16. Hydrogeochemical exploration for uranium within the Athabasca Basin, northern Saskatchewan

    As part of exploration programs for unconformity-related uranium deposits, the chemistry of deep ground waters has been studied from throughout the Athabasca Basin. Samples have been collected from routine, small-diameter, exploration diamond drillholes, and considerable emphasis has been placed on ensuring that they represent true ground waters. The authors have measured both major and minor constituents, including various uranium daughter products. Ground-water samples collected from the vicinity of uranium mineralization have consistently high levels of uranium, radium, radon and helium. Although they have not been able to establish the maximum extent of the hydrogeochemical anomalies in this environment, they have detected anomalies at distances of up to tens of meters from known mineralization. (orig.)

  17. Astronomy in the Ancient Caucasus

    Simonia, Irakli; Jijelava, Badri

    This chapter discusses the role of recurrent heavenly phenomena in the formation of ancient cultural traditions. Artifacts bearing witness to astronomical and calendrical practices in the ancient Caucasus are described and we analyze the significance of the "boats of the sun" petroglyphs at Gobustan in Azerbaijan, the solar station at Abuli in Georgia, and the "sky dial" at Carahunge in Armenia. Similarities and differences between the ancient cultures of the region are discussed. Finally, we present the results of the latest field research and new facts and hypotheses.

  18. Tectonics, recent geodynamics and seismicity of Azerbaijan part of the Greater Caucasus

    Aliyev, Fuad; Kangarli, Talat; Rahimov, Fuad; Murtuzov, Zaur; Aliyev, Ziya


    Transition area of the Eastern Caucasus - Caspian Megadepression corresponds to a periclinal submergence zone of the mountain folded structure of the Greater Caucasus under Pliocene-Holocenic sedimentary complex of Caspian megabasin. Being a part of Alpine-Himalayan folded belt, Greater Caucasus has formed during alpine stage of tectogenesis under geodynamic conditions of convergent interactions between Northern and Southern Caucasus continental microplates. This process has been accompanied by pseudosubduction of the first plate under the second with formation of allochtonous accretion prism above underthrust zone. Modern folding and napping structure of the orogeny has formed as a result of the horizontal movements of different phases and subphases of alpine tectogenesis, that are presented represented by Late Cimmerian - Wallachian tectonic phases within Azerbaijan territory. Limited by meridional fault-slip zones, Caspian megadepression present itself as a young structure that layered on sublatitudinal convergent zone and developed during Late Miocene (10 million years ago) as a flexure zone between two indenters which actively move northward provoking their separation from the African continent and Arabian plate in the west and secession from Central Iranian plate of the Lut block in the east. The acting movement of Arabian plate to the north results in accumulation of the horizontal stress at the current stage of tectogenesis. Current process reveals itself both in the fragmentation of Southern and Northern Caucasus continental microplates into various-size blocks along the general and anti-Caucasus trended faults, and in consideration horizontal and vertical movements within the convergence zone. All these factors define the complexity of geodynamic condition revealed here, in which seismic activity of a transition zone become apparent. There exist the seismic zones here that are confined both to a convergence line and to the fault zones that confine Caspian

  19. Cenozoic subsurface stratigraphy and structure of the Salar de Atacama Basin, northern Chile

    Jordan, T. E.; Mpodozis, C.; Muñoz, N.; Blanco, N.; Pananont, P.; Gardeweg, M.


    Sequence mapping of industry seismic lines and their correlation to exposed stratigraphic formations enable a description of the evolution of the nonmarine Salar de Atacama Basin. This major tectonic basin, located in the present-day forearc of the northern Chilean Andes, was first defined topographically by late Cretaceous inversion of the Jurassic-early Cretaceous extensional Tarapacá backarc Basin. Inversion led to both the uplift of the Cordillera de Domeyko and subsidence of the Salar de Atacama Basin along its eastern flank. The basin evolved from a continental backarc in the Cretaceous and Paleogene to a forearc tectonic setting during the Neogene. The principal causes of basin-scale tectonic subsidence include late Cretaceous and earliest Paleocene shortening and Oligocene-early Miocene localized extension. The basin was not completely filled by late Cretaceous (Purilactis Group, sequence G) and Paleocene (sequence H) strata, and its empty space persisted through the Cenozoic. Eocene deformation caused long-wavelength rotation of a deeply weathered surface, generating an erosional unconformity across which coarse clastic strata accumulated (sequence J). Oligocene-early Miocene normal faulting, perhaps in a transtensional environment, repositioned the western basin margin and localized hangingwall subsidence, leading to the accumulation of thousands of meters of evaporitic strata (sequence K, Paciencia Group). By the close of the early Miocene, shortening resumed, first uplifting the intrabasinal Cordillera de la Sal and later generating Pliocene blind reverse faults within the topographically lowest part of the basin. Unequal deposition and tilting across the nascent Cordillera de la Sal induced diapirism of the Paciencia Group halite. In combination, inherited accommodation space and new tectonic subsidence, plus local salt-withdrawal subsidence, shaped the distribution of Upper Miocene-Recent ignimbrites, evaporites, and clastics (sequence M and Vilama

  20. Diversity of Bacteroidetes in high altitude saline evaporitic basins in northern Chile

    Dorador, Cristina; Meneses, D.; Urtuvia, V.; Demergasso, C.; Vila, I; Witzel, K.-P.; Imhoff, Johannes F.


    The phylum Bacteroidetes represents one of the most abundant bacterial groups of marine and freshwater bacterioplankton. We investigated the diversity of Bacteroidetes in water and sediment samples from three evaporitic basins located in the highlands of northern Chile. We used both 16S rRNA gene clone libraries created with targeted Bacteroidetes-specific primers and separation of specifically amplified gene fragments by denaturing gradient gel electrophoresis (DGGE). DGGE analysis revealed ...

  1. Sustainable Transformations of Water Supply Regimes. The Cuvelai-Etosha Basin in Central Northern Namibia.

    Zimmermann, Martin


    In this thesis, an interdisciplinary modelling approach for water resources management and its application is presented that is able to deal with socio-technical systems that are characterised by a multiplicity of variables, interdependencies, and actors. The case study area is the Cuvelai-Etosha Basin, which is located in central northern Namibia. Approximately 850,000 people or 40 % of the Namibian population live in this area, which comprises only about 14 % of the country’s area. The regi...

  2. Competition, Cooperation, and the Emergence of Regional Centers in the Northern Lake Titicaca Basin, Peru

    Levine, Abigail Ruth


    Regional centers with dense populations developed in the Titicaca Basin during the late Middle (ca. 1300-500 BC) and early Upper Formative (ca. 500 BC- AD 400) Periods. These aggregated settlements have long been considered the hallmark of intermediate societies. This dissertation focuses on the transition from small village societies to ones with pronounced social, political, and economic hierarchies. In the northern Titicaca region, only two sites--Taraco and Pukara--became powerful cent...

  3. Analysis on Structural Control of Coal Distribution in the Northern Qaidam Basin, NW China

    LIU Tianji; WANG Tong; ZHAN Wenfeng


    The distribution of the Jurassic coal measures in the northern Qaidam Basin is obviously controlled by the regional structures. Based on the existing data of coalfield exploration and combined with the analysis of coalfield basement structures, features of the main faults, and the distribution of coal measures, this paper brings forward a scheme of coalfield tectonic divisional units and the definition of the coal-controlling structural styles in the northern Qaidam Basin. The structure control of the distribution of coal measures is further discussed. Several stages of regional tectonic activities since the Indosinian has led to the distribution of coal measures into the characteristics of zonation from the north to south and block from east to west. The results indicate that the structural deformations are the most intense in the front of the three uplifted belts, which are characterized by the combination of thrusts. The coal measures are uplifted to the shallow formations, and are easy to be exploited, but the scale of mines is small because of serious damages by the coal distribution. On the contrary, the stress and strain are weak in the three depressions, with the coal-controlling structural styles being mainly the thrust-fold and thrust-monocline combinations. The distribution of coals in the depressions is relatively stable. The shallower part of the depression will become the key areas for exploration and development of coal resources in the northern Qaidam Basin.

  4. Tectonic control on the Late Quaternary hydrography of the Upper Tiber Basin (Northern Apennines, Italy)

    Benvenuti, Marco; Bonini, Marco; Moroni, Adriana


    We examine the intramontane Upper Tiber Basin in the Northern Apennines (central Italy), where sub-orthogonal fault systems forced river deviation and the abandonment of alluvial fans since the late Middle Pleistocene. Archaeological material, spanning the Middle Palaeolithic-Iron Age, was collected mostly from the surface of the Late Quaternary alluvial landforms and related deposits (MUP and HOL units). This information contributed to the partial dating of seven major stages of drainage development. Normal faults parallel and transverse to the basin trend were active at different times and conditioned the valley pattern of the Middle (MUP1-2)-Late (MUP3) Pleistocene Tiber, Singerna, Sovara and Tignana rivers, which still flow today into the basin. The MUP1 and the MUP3 fans were beheaded by the displacement of their feeder valleys along the basin-transverse Carmine and Montedoglio faults. In some cases, the former feeder rivers underwent stream piracy but their courses mostly deviated in response of the topographic gradient created by faulting, as well as through the incision of new valleys that exploited the lithological contrast along the fault lines. The MUP3 Tignana fan was abandoned mostly due to the activity of the basin-parallel, dip-slip Sansepolcro fault. Subsidence driven by the basin-parallel Anghiari and Sansepolcro fault systems also provided the accommodation space for the MUP3 and HOl1-2 Afra fans between Late Pleistocene and early-mid Holocene. This study exemplifies the interplay between longitudinal and transverse fault systems, and the Late Quaternary hydrographic evolution of an extensional basin settled in the axial zone of an active fold-and-thrust belt. Although the faulting has interacted with the forcing exerted by the Late Quaternary climate fluctuations on the basin drainage systems, the tectonic rates are sufficiently high to represent the prime controller on base-level change and drainage routing patterns.

  5. Reactive Transport of Nitrate in Northern California Groundwater basins: An Integrated Characterization and Modeling Approach

    Esser, B. K.; Moran, J. E.; Hudson, G. B.; Carle, S. F.; McNab, W.; Tompson, A. F.; Moore, K.; Beller, H.; Kane, S.; Eaton, G.


    More than 1/3 of active public drinking water supply wells in California produce water with nitrate-N levels indicative of anthropogenic inputs (> 4 mg/L). Understanding how the distribution of nitrate in California groundwater basins will evolve is vital to water supply and infrastructure planning. To address this need, we are studying the basin-scale reactive transport of nitrate in the Livermore and Llagas basins of Northern California. Both basins have increasingly urban populations heavily reliant on groundwater. A distinct nitrate "plume" exists in the Livermore Basin (Alameda County) whereas pervasive nitrate contamination exists in shallow groundwaters of the Llagas Basin (Santa Clara County). The sources and timing of nitrate contamination in these basins are not definitively known; septic systems, irrigated agriculture and livestock operations exist or have existed in both areas. The role of denitrification in controlling nitrate distribution is also unknown; dissolved oxygen levels are sufficiently low in portions of each basin as to indicate the potential for denitrification. We have collected water from 60 wells, and are determining both groundwater age (by the 3H/3He method) and the extent of denitrification (by the excess N2 method). Excess nitrogen is being determined by both membrane-inlet and noble gas mass spectrometry, using Ar and Ne content to account for atmospheric N2. We are also analyzing for stable istotopes of nitrate and water, nitrate co-contaminants, and general water quality parameters. Preliminary analysis of archival water district data from both basins suggests positive correlations of nitrate with Ca+2, Mg+2 and bicarbonate and negative correlation with pH. In the Llagas Basin, a negative correlation also exists between nitrate and temperature. Flow path-oriented reactive transport modeling is being explored as a tool to aid in the identification of both the sources of nitrate and evidence for denitrification in both basins

  6. Tectonic Subsidence Analysis of the Pearl River Mouth Basin, Northern South China Sea

    Tang, X.; Huang, S. S. X. E. C.; Zhuang, W.; LIU, Z.; Duan, W.; Hu, S.


    The Pearl River Mouth Basin (PRMB hereafter) in the northern margin of the South China Sea has attracted great attention not only because of its special tectonic location but also for its abundant hydrocarbon resources. Tectonic evolution controls the petroleum geological condition of hydrocarbon-bearing basins. Efforts have been made to understand the tectonic evolution of this basin. However, many issues about the tectonic features and the evolution process of this basin, such as the age of the breakup unconformities and the anomalously accelerated subsidence during the post-rifting stage, remain controversial. Here we employ tectonic subsidence analysis of sedimentary basins, a technique of removing isostatic loading and compaction effects by back-stripping, to investigate the tectonic controls on the basin formation of the PRMB. We performed the analysis on 4 drill wells and 43 synthetic wells constructed based on recently acquired seismic profiles. The result shows that tectonic subsidence in the eastern sags of the PRMB began to decrease at ~30Ma while in the western sags the onset was ~23.8Ma. This suggests that the break-up time i.e. the end of rifting in the PRMB is earlier in the eastern sags than in the western sags. Abnormally accelerated tectonic subsidence occurred between 17.5-16.4Ma during the post-rifting stage, at an average subsidence rate as high as 301.9m/Ma. This phenomenon discriminates the PRMB from the category of classical Atlantic passive continental marginal basins, of which the tectonic subsidence during the post-rifting stage decays exponentially. The main objective of this paper is to provide insights into the geological and geodynamic evolution of the PRMB. The result bears significance to hydrocarbon exploration in this region.

  7. Miocene woods from the Qaidam Basin on northern Qinghai-Tibet Plateau with implications for paleoenvironmental change

    Cheng, Ye-Ming; Yang, Xiao-Nan


    The Qaidam Basin with the most complete Cenozoic sedimentary preservation in northern Qinghai-Tibet Plateau is a key area for studying uplift and environmental change of the plateau. Three types of woods, Ulmus (Ulmaceae), Leguminosae (?) (angiosperm) and Cupressaceae (gymnosperm) were recognized from the large-scale preservation of fossil woods in late Miocene Shang Youshashan Formation in northern Qaidam Basin on the Qinghai-Tibet Plateau. Both investigations of their Nearest Living Relatives (NLRs) and previous grassland mammal evidences suggest that there have been temperate deciduous broad-leaved forest and needle-leaved forest with grass in northern Qaidam Basin during the late Miocene in contrast to the desert vegetation found there nowadays. The presence of the ancient forest steppe further implies that the southern part of the plateau used to be adequately low, so that the Indian and East Asian monsoons could approach the northern area and to accommodate the vegetation in late Miocene.

  8. Hydrogeochemistry of high-fluoride groundwater at Yuncheng Basin, northern China

    Hydrogeochemical and environmental isotope methods were integrated to delineate the spatial distribution and enrichment of fluoride in groundwater at Yuncheng Basin in northern China. One hundred groundwater samples and 10 Quaternary sediment samples were collected from the Basin. Over 69% of the shallow groundwater (with a F− concentration of up to 14.1 mg/L), 44% of groundwater samples from the intermediate and 31% from the deep aquifers had F− concentrations above the WHO provisional drinking water guideline of 1.5 mg/L. Groundwater with high F− concentrations displayed a distinctive major ion chemistry: Na-rich and Ca-poor with a high pH value and high HCO3− content. Hydrochemical diagrams and profiles and hydrogen and oxygen isotope compositions indicate that variations in the major ion chemistry and pH are controlled by mineral dissolution, cation exchange and evaporation in the aquifer systems, which are important for F− mobilization as well. Leakage of shallow groundwater and/or evaporite (gypsum and mirabilite) dissolution may be the major sources for F− in groundwater of the intermediate and deep aquifers. - Highlights: • High-F− groundwater widely occurs in Yuncheng Basin of northern China. • High-F− groundwater is Na and HCO3-rich and Ca-poor, with high pH. • Major hydrogeochemical processes are mineral dissolution, ion exchange and evaporation. • Shallow groundwater leakage/evaporite dissolution may cause F enrichment in lower aquifers

  9. Prospect analysis for sandstone-type uranium mineralization in the northern margin of Qaidam basin

    Affected by the regional geological structural evolution, a set of sedimentary structure, i.e. the construction of coal-bearing classic rocks which is in favor of the sandstone-type uranium mineralization has deposited in the northern margin of Qaidam Basin since Meso-Cenozoic. A NWW thrust nappe tectonic belt, i.e. the ancient tectonic belt which is the basis for the development of ancient interlayer oxidation zone formed by the tectonic reverse in late Jurassic and Cretaceous. The Mid and late Jurassic layer was buried by the weak extension in Paleogene and the depression in early Neogene. The extrusion reversal from late Neogene to Quaternary made the basin into the development era of the modern interlayer oxidation zone. It can be concluded that the layer of the northern margin of Qaidam Basin has the premise for the formation of sandstone-type uranium ore. Based on the analysis of the characteristics of the thrust belt, the structure of the purpose layer, the sand body, the hydrogeology, the interlayer oxidation zone and uranium mineralization, the results indicated that the ancient interlayer oxidation zone is the prospecting type of sandstone-type uranium ore. Beidatan and the east of Yuqia are the favorable prospective area of sandstone-type uranium mineralization. (authors)

  10. Characteristics and genesis of clay minerals in the northern margin of the Qaidam Basin

    Wang Linlin; Jiang Bo; Peng Dehua; Yin Chengming; Zeng Chunlin


    In order to develop appropriate reservoir protection measures in the northern margin of the Qaidam Basin and improve its oil and gas recovery efficiency, characteristics of clay minerals from eleven clay rock samples from the northern margin of the Qaidam Basin were investigated using X-ray diffraction analysis, the Scanning Electron Microscope (SEM) and energy spectrum analysis. Clay mineral composition and distribution characteristics of the main hydrocarbon reservoirs, I.e., from the Jurassic and Paleogene-Neogene, were explored. We analyzed the main factors which affected these attributes. The results show that the major clay minerals in the northern margin are chlorite, kaolinite, illite, smectite and illite/smectite inter-stratified minerals, Illite is the most widely spread clay mineral in this area.Chlorite is mainly found in the entire Neogene and in shallow horizons of the Paleogene. Smectite is enriched in the shallow Paleogene-Neogene. There are large amounts of kaolinite and illite/smectite inter-stratified minerals in the Jurassic. The major factors affecting the different development of clay minerals in the region are properties of parent rocks, paleoclimate and paleowater media conditions,diagenesis transformation, tectonic and terrain conditions.

  11. Evidence for a broadly distributed Samoan-plume signature in the northern Lau and North Fiji Basins

    Price, Allison A.; Jackson, Matthew G.; Blichert-Toft, Janne; Hall, Paul S.; Sinton, John M.; Kurz, Mark D.; Blusztajn, Jerzy


    enrichment of lavas in the northern Lau Basin may reflect the influx of Samoan-plume mantle into the region. We report major and trace element abundances and He-Sr-Nd-Hf-Pb-isotopic measurements for 23 submarine volcanic glasses covering 10 locations in the northern Lau and North Fiji Basins, and for three samples from Wallis Island, which lies between Samoa and the Lau Basin. These data extend the western limit of geochemical observations in the Basins and improve the resolution of North-South variations in isotopic ratios. The Samoan hot spot track runs along the length of the northern trace of the Lau and North Fiji Basins. We find evidence for a Samoan-plume component in lavas as far West as South Pandora Ridge (SPR), North Fiji Basin. Isotopic signatures in SPR samples are similar to those found in Samoan Upolu shield lavas, but show a slight shift toward MORB-like compositions. We explain the origin of the enriched signatures by a model in which Samoan-plume material and ambient depleted mantle undergo decompression melting during upwelling after transiting from beneath the thick Pacific lithosphere to beneath the thin lithosphere in the northern Lau and North Fiji Basins. Other lavas found in the region with highly depleted isotopic signatures may represent isolated pockets of depleted mantle in the basins that evaded this enrichment process. We further find that mixing between the two components in our model, a variably degassed high-3He/4He Samoan component and depleted MORB, can explain the diversity among geochemical data from the northern Lau Basin.

  12. Structural style and Basin Formation in Deep-water Area of Northern South China Sea

    di, Z.; Zhen, S.; Xiong, P.; Min, C. C.


    In the deep-water area of northern South China Sea (SCS) developed a series of sedimentary basins. Active exploration for deep-water hydrocarbon has begun in these areas since this century. The well LW3-1-1 at water depth of 1480m in the BaiYun Sag (BYS) of the Pearl River Mouth Basin in 2006 discovered 56m layer of pure gas, demonstrated the good hydrocarbon potential of the area. Wide-angle seismic profiling has verified the transitional type of crust in the slope areas. The Moho surface shoals step-by-step from 30-29km under the shelf, ~15 km under the slope, and ~12km under the abyssal plain. Moho also rises beneath depocenters, mirroring the shape of sedimentary basement. The crustal thickness at the center of the BYS is Pacific Ocean towards the East Eurasian margin. The stress field in the East Eurasian margin changed abruptly in Late Cretaceous. Rifting started in the entire margin and eventually led to the opening of the SCS in late Early Oligocene. Large sedimentary basins developed in the margins of the SCS. Paleogene lacustrine sediments contain hydrocarbon sources, while traps are mostly found in Neogene marine strata. The structure of the northern SCS shows clear W-E variation, divided into NE-, NEE-, and NE-trending segments by two major NW-SE transfer faults. The Southern Depression of the Qiongdongnan Basin to the west is characterized by NE-trending half grabens. The BYS at the central segment is characterized by NEE-trending composite grabens and down warps with relatively small offset of boundary faults. To the east the Chaoshan Depression is composed of Mesozoic strata under very thin (deep-water basins is different from that of shallow-water basins. A study is ongoing to explore the basin formation mechanism, taking into account of the factors of abnormal lithosphere rheology, active mantle underplating and magmatic heating, lower crust flow, as well as the superposition of later extensional events. The study is supported by NSFC grants

  13. Federally owned coal and Federal lands in the northern and central Appalachian Basin coal regions

    Susan J. Tewalt


    The US Geological Survey (USGS) assessed five coals beds or coal zones in the northern and central Appalachian Basin coal regions for the National Coal Resource Assessment: the Pittsburgh coal bed, the Upper Freeport coal bed, the Fire Clay coal zone, the Pond Creek coal zone, and the Pocahontas No. 3 coal bed. The assessment produced stratigraphic and geochemical databases and digital coal maps, or models, which characterized the coal beds and coal zones. Using the assessment models, the USGS estimated original and remaining (unmined) resources for these coal beds or zones. The Appalachian Basin assessment was conducted in collaboration with the State geological surveys of West Virginia, Pennsylvania, Ohio, Maryland, Kentucky, and Virginia. 3 refs., 7 figs.

  14. Coal resources of selected coal beds and zones in the northern and central Appalachian Basin

    Leslie Ruppert; Susan Tewalt; Linda Bragg


    The U.S. Geological Survey (USGS) is completing a National Coal Resource Assessment of five coal-producing regions of the United States, including the Appalachian Basin. The USGS, in cooperation with the State geological surveys of Kentucky, Maryland, Ohio, Pennsylvania, Virginia, and West Virginia, has completed a digital coal resource assessment of five of the top-producing coal beds and coal zones in the northern and central Appalachian Basin coal regions -- the Pittsburgh coal bed, the Upper Freeport coal bed, the Fire Clay and Pond Creek coal zones, and the Pocahontas No. 3 coal bed. Of the 93 billion short tons of original coal in these units, about 66 billion short tons remain. 2 refs., 5 figs., 2 tabs.

  15. Visan miospore biostratigraphy and correlation of the Poti Formation (Parnaba Basin, northern Brazil).

    Melo; Loboziak


    The Poti Formation, which consists mainly of sandstones with minor proportions of carbonaceous shales and other siliciclastic lithologies, represents all the Viséan strata thus far recorded in the Parnaíba Basin, northern Brazil.Well-preserved miospores featuring species with both Southern Euramerican and Gondwanan affinities have been recovered from this formation in four well sections. The most characteristic species are listed in this paper, and brief systematic descriptions are presented for the most significant species, along with comments on their biostratigraphy. A new generic combination is proposed: Cordylosporites magnidictyus (Playford and Helby) Loboziak and Melo comb. nov. Comparisons with miospores illustrated from the Grand Erg Occidental, Algerian Sahara, are tentatively proposed.In terms of the Western European Carboniferous palynozonation, miospore assemblages from the Poti Formation are assignable to the Perotrilites tessellatus-Schulzospora campyloptera (TC)-Raistrickia nigra-Triquitrites marginatus (NM) zonal range. This corresponds to the upper part of the Holkerian and the whole Asbian, which are British regional stages for the lower to middle parts of the upper Viséan. The Viséan age formerly attributed to biostratigraphic interval XII of Petrobras' regional palynostratigraphic scheme is therefore confirmed. As already noted in our recent investigations of the Faro Formation in the Amazon Basin and equivalent strata of the Solimões Basin, latest Tournaisian and early to middle Viséan sections are either absent or barren of characteristic miospores in the Parnaíba Basin as well. PMID:11042330

  16. Latest Miocene to Quaternary deformation in the southern Chaiwopu Basin, northern Chinese Tian Shan foreland

    Lu, Honghua; Wang, Zhen; Zhang, Tianqi; Zhao, Junxiang; Zheng, Xiangmin; Li, Youli


    Basinward propagation of fold and thrust belts is a crucial geological process accommodating Cenozoic crustal shortening within the India-Eurasia collision zone. Anticlinal growth strata in the southern Chaiwopu Basin (a piggyback basin) of the northern Chinese Tian Shan foreland record basinward encroachment of the Tian Shan along the Junggar Frontal Thrust Fault. A new magnetostratigraphic section constrains the onset of syntectonic growth strata at circa 6.4 Ma and suggests synchronous basinward thrusting and propagation of the Tian Shan. The intense alluviation in the southern Chaiwopu Basin ceased at circa 0.55 Ma due to significant anticlinal growth and its resultant river incision. More recent anticlinal growth and deformation during the late Quaternary are revealed by folded river terraces developing across the anticline. The terrace height profile indicates that terrace T1H has been vertically offset about 0.6 m by thrust faulting since its formation at about 7 Ka. The stratigraphic and geomorphic data presented in this work are helpful to understand the initiation of thrust-related folding, as well as aggradation and subsequent incision, in foreland basins of the Tian Shan in relation to the India-Asia collision.

  17. Geophysical observations on northern part of Georges Bank and adjacent basins of Gulf of Maine

    Oldale, R.N.; Hathaway, J.C.; Dillon, William P.; Hendricks, J.D.; Robb, James M.


    Continuous-seismic-reflection and magnetic-intensity profiles provide data for inferences about the geology of the northern part of Georges Bank and the basins of the Gulf of Maine adjacent to the bank. Basement is inferred to be mostly sedimentary and volcanic rocks of Paleozoic age that were metamorphosed and intruded locally by felsic and mafic plutons near the end of the Paleozoic Era. During Late Triassic time, large fault basins formed within the Gulf of Maine and probably beneath Georges Bank. The fault basins and a possible major northeast-trending fault zone beneath the northern part of the bank probably formed as a result of the opening Atlantic during the Mesozoic. Nonmarine sediments, associated with mafic flows and intrusive rocks, were deposited in the fault basins as they formed. The upper surface of the Triassic and pre-Triassic rocks that comprise basement is an unconformity that makes up much of the bottom of the Gulf of Maine. Depth to the basement surface beneath the gulf differ greatly because of fluvial erosion in Tertiary time and glacial erosion in Pleistocene time. Beneath the northern part of Georges Bank the basement surface is smoother and slopes southward. Prominent valleys, cut before Late Cretaceous time, are present beneath this part of the bank. Cretaceous, Tertiary, and possibly Jurassic times were characterized by episodes of coastal-plain deposition and fluvial erosion. During this time a very thick wedge of sediment, mostly of Jurassic(?) and Cretaceous ages, was deposited on the shelf. Major periods of erosion took place at the close of the Cretaceous and during the Pliocene. Fluvial erosion during the Pliocene removed much of the coastal-plain sedimentary wedge and formed the Gulf of Maine. Pleistocene glaciers eroded all but a few remnants of the coastal-plain sediments within the gulf and deposited a thick section of drift against the north slope of Georges Bank and a thin veneer of outwash on the bank. Marine sediments were


    Mellors, R; Gok, R; Pasyanos, M; Skobeltsyn, G; Teoman, U; Godoladze, T; Sandvol, E


    The southwest edge of Eurasia is a tectonically and structurally complex region that includes the Caspian and Black Sea basins, the Caucasus Mountains, and the high plateaus south of the Caucasus. Using data from 25 broadband stations located in the region, new estimates of crustal and upper mantle thickness, velocity structure, and attenuation are being developed. Receiver functions have been determined for all stations. Depth to Moho is estimated using slant stacking of the receiver functions, forward modeling, and inversion. Moho depths along the Caspian and in the Kura Depression are in general poorly constrained using only receiver functions due to thick sedimentary basin sediments. The best fitting models suggest a low velocity upper crust with Moho depths ranging from 30 to 40 km. Crustal thicknesses increase in the Greater Caucasus with Moho depths of 40 to 50 km. Pronounced variations with azimuth of source are observed indicating 3D structural complexity and upper crustal velocities are higher than in the Kura Depression to the south. In the Lesser Caucasus, south and west of the Kura Depression, the crust is thicker (40 to 50 km) and upper crustal velocities are higher. Work is underway to refine these models with the event based surface wave dispersion and ambient noise correlation measurements from continuous data. Regional phase (Lg and Pg) attenuation models as well as blockage maps for Pn and Sn are being developed. Two methods are used to estimate Q: the two-station method to estimate inter-station Q and the reversed, two-station, two event method. The results are then inverted to create Lg and Pg Q maps. Initial results suggest substantial variations in both Pg and Lg Q in the region. A zone of higher Pg Q extends west from the Caspian between the Lesser and Greater Caucasus and a narrow area of higher Lg Q is observed.

  19. Recognition of relict Mesozoic Dongsha Basin in the northern margin, South China Sea and its implication

    Yan, Pin; Wang, Yanlin


    The Pearl River Mouth Basin (PRMB) is dominated by NE-trending rift architecture produced mainly during Cenozoic Era. It comprises a series of grabens built up with thick Paleogene and thick Neogene sediments, up to 12000 m, and dividing basement highs composing Yanshanian granitic rocks. Though previously considered as one constituent part of PRMB in the southeast, Dongsha Basin displays major differences in sedimentary architecture and tectonic framework. Firstly, Dongsha Basin is characterized by a prominent angular unconformity, interpreted as a spectacular planation or rough erosion surface which separates the sediment column into two distinct parts. It is interpreted with accumulating seismic and drill data that the underlying strata comprise Early Cretaceous terrestrial, Jurassic marine and possibly Triassic sedimentary rocks totaling to 4~9 km thick, whereas the overlying strata are very thin (usually 0.5~1 km in whole) composing mainly Neogene sediments. The major sedimentary hiatus between them corresponds to the Late Cretaceous to mid-Miocene Epoch, well during the rifting to spreading process when the PRMB developed. Secondly, unlike the PRMB, the Dongsha Basin has suffered considerably less extension except its boundary areas, and actually remained as a relatively stable block though Cenozoic Era. Moreover, there are a few compressive open fold structures within the buried Mesozoic strata over the central Dongsha Basin. These folds trend in NNE and are characterized mostly by few minor growing upthrust faults with offsets in the order of few tens to hundreds meter. The upthrust faults dipped mostly southeastward against the northwestward subduction of paleo-Pacific plate as postulated in other previous study. The blind folds featured more like back-thrust growth tectonics, formed a broad NNE-SSW trending belt, obviously oblique to the trend of northern margin of the South China Sea and the PRMB as well. In a few recent models, the most prominent

  20. Lithospheric Velocity Structure of the Anatolain plateau-Caucasus-Caspian Regions

    Gok, R; Mellors, R J; Sandvol, E; Pasyanos, M; Hauk, T; Yetirmishli, G; Teoman, U; Turkelli, N; Godoladze, T; Javakishvirli, Z


    Anatolian Plateau-Caucasus-Caspian region is an area of complex structure accompanied by large variations in seismic wave velocities. Despite the complexity of the region little is known about the detailed lithospheric structure. Using data from 29 new broadband seismic stations in the region, a unified velocity structure is developed using teleseismic receiver functions and surface waves. Love and Rayleigh surface waves dispersion curves have been derived from event-based analysis and ambient-noise correlation. We jointly inverted the receiver functions with the surface wave dispersion curves to determine absolute shear wave velocity and important discontinuities such as sedimentary layer, Moho, lithospheric-asthenospheric boundary. We combined these new station results with Eastern Turkey Seismic Experiment results (29 stations). Caspian Sea and Kura basin underlained by one of the thickest sediments in the world. Therefore, short-period surface waves are observed to be very slow. The strong crustal multiples in receiver functions and the slow velocities in upper crust indicate the presence of thick sedimentary unit (up to 20 km). Crustal thickness varies from 34 to 52 km in the region. The thickest crust is in Lesser Caucasus and the thinnest is in the Arabian Plate. The lithospheric mantle in the Greater Caucasus and the Kura depression is faster than the Anatolian Plateau and Lesser Caucasus. This possibly indicates the presence of cold lithosphere. The lower crust is slowest in the northeastern part of the Anatolian Plateau where Holocene volcanoes are located.

  1. Diversity of Bacteroidetes in high-altitude saline evaporitic basins in northern Chile

    Dorador, Cristina; Meneses, Daniela; Urtuvia, Viviana; Demergasso, Cecilia; Vila, Irma; Witzel, Karl-Paul; Imhoff, Johannes F.


    The phylum Bacteroidetes represents one of the most abundant bacterial groups of marine and freshwater bacterioplankton. We investigated the diversity of Bacteroidetes in water and sediment samples from three evaporitic basins located in the highlands of northern Chile. We used both 16S rRNA gene clone libraries created with targeted Bacteroidetes-specific primers and separation of specifically amplified gene fragments by denaturing gradient gel electrophoresis (DGGE). DGGE analysis revealed a reduced richness of these organisms in samples from Salar de Huasco (two to four DGGE bands) increasing in Salar de Ascotán (two to seven DGGE bands) and Laguna Tebenquiche at Salar de Atacama (four to eight DGGE bands). Cluster analysis (WPGMA) of DGGE bands showed that bands from Salar de Huasco and Salar de Ascotán grouped together and samples from Salar de Atacama formed separate clusters in water and sediment samples, reflecting different Bacteroidetes communities between sites. Most of the sequences analyzed belonged to the family Flavobacteriaceae and clustered with the genera Psychroflexus, Gillisia, Maribacter, Muricauda, Flavobacterium, and Salegentibacter. The most abundant phylotype was highly related to Psychroflexus spp. and was recovered from all three study sites. The similarity of the analyzed sequences with their closest relatives in GenBank was typically Culture efforts will be necessary to get a better description of the diversity of this group in saline evaporitic basins of northern Chile.

  2. Extraordinarily thick-boned fish linked to the aridification of the Qaidam Basin (northern Tibetan Plateau).

    Chang, Meemann; Wang, Xiaoming; Liu, Huanzhang; Miao, Desui; Zhao, Quanhong; Wu, Guoxuan; Liu, Juan; Li, Qiang; Sun, Zhencheng; Wang, Ning


    Scattered with numerous salt lakes and approximately 2,700-3,200 m above sea level, the giant Qaidam inland basin on the northern Tibetan Plateau has experienced continuing aridification since the beginning of the Late Cenozoic as a result of the India-Asia plate collision and associated uplift of the Tibetan Plateau. Previous evidence of aridification comes mainly from evaporite deposits and salinity-tolerant invertebrate fossils. Vertebrate fossils were rare until recent discoveries of abundant fish. Here, we report an unusual cyprinid fish, Hsianwenia wui, gen. et sp. nov., from Pliocene lake deposits of the Qaidam Basin, characterized by an extraordinarily thick skeleton that occupied almost the entire body. Such enormous skeletal thickening, apparently leaving little room for muscles, is unknown among extant fish. However, an almost identical condition occurs in the much smaller cyprinodontid Aphanius crassicaudus (Cyprinodonyiformes), collected from evaporites exposed along the northern margins of the Mediterranean Sea during the Messinian desiccation period. H. wui and A. crassicaudus both occur in similar deposits rich in carbonates (CaCO(3)) and sulfates (CaSO(4)), indicating that both were adapted to the extreme conditions resulting from the aridification in the two areas. The overall skeletal thickening was most likely formed through deposition of the oversaturated calcium and was apparently a normal feature of the biology and growth of these fish. PMID:18757732

  3. Hydrogeochemistry of high-fluoride groundwater at Yuncheng Basin, northern China

    Li, Chengcheng [State Key Laboratory of Biogeology and Environmental Geology and School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China); Gao, Xubo, E-mail: [State Key Laboratory of Biogeology and Environmental Geology and School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China); University of Texas at Austin, Austin, TX, 78705 (United States); Wang, Yanxin, E-mail: [State Key Laboratory of Biogeology and Environmental Geology and School of Environmental Studies, China University of Geosciences, Wuhan 430074 (China)


    Hydrogeochemical and environmental isotope methods were integrated to delineate the spatial distribution and enrichment of fluoride in groundwater at Yuncheng Basin in northern China. One hundred groundwater samples and 10 Quaternary sediment samples were collected from the Basin. Over 69% of the shallow groundwater (with a F{sup −} concentration of up to 14.1 mg/L), 44% of groundwater samples from the intermediate and 31% from the deep aquifers had F{sup −} concentrations above the WHO provisional drinking water guideline of 1.5 mg/L. Groundwater with high F{sup −} concentrations displayed a distinctive major ion chemistry: Na-rich and Ca-poor with a high pH value and high HCO{sub 3}{sup −} content. Hydrochemical diagrams and profiles and hydrogen and oxygen isotope compositions indicate that variations in the major ion chemistry and pH are controlled by mineral dissolution, cation exchange and evaporation in the aquifer systems, which are important for F{sup −} mobilization as well. Leakage of shallow groundwater and/or evaporite (gypsum and mirabilite) dissolution may be the major sources for F{sup −} in groundwater of the intermediate and deep aquifers. - Highlights: • High-F{sup −} groundwater widely occurs in Yuncheng Basin of northern China. • High-F{sup −} groundwater is Na and HCO{sub 3}-rich and Ca-poor, with high pH. • Major hydrogeochemical processes are mineral dissolution, ion exchange and evaporation. • Shallow groundwater leakage/evaporite dissolution may cause F enrichment in lower aquifers.

  4. Towards large scale modelling of wetland water dynamics in northern basins.

    Pedinotti, V.; Sapriza, G.; Stone, L.; Davison, B.; Pietroniro, A.; Quinton, W. L.; Spence, C.; Wheater, H. S.


    Understanding the hydrological behaviour of low topography, wetland-dominated sub-arctic areas is one major issue needed for the improvement of large scale hydrological models. These wet organic soils cover a large extent of Northern America and have a considerable impact on the rainfall-runoff response of a catchment. Moreover their strong interactions with the lower atmosphere and the carbon cycle make of these areas a noteworthy component of the regional climate system. In the framework of the Changing Cold Regions Network (CCRN), this study aims at providing a model for wetland water dynamics that can be used for large scale applications in cold regions. The modelling system has two main components : a) the simulation of surface runoff using the Modélisation Environmentale Communautaire - Surface and Hydrology (MESH) land surface model driven with several gridded atmospheric datasets and b) the routing of surface runoff using the WATROUTE channel scheme. As a preliminary study, we focus on two small representative study basins in Northern Canada : Scotty Creek in the lower Liard River valley of the Northwest Territories and Baker Creek, located a few kilometers north of Yellowknife. Both areas present characteristic landscapes dominated by a series of peat plateaus, channel fens, small lakes and bogs. Moreover, they constitute important fieldwork sites with detailed data to support our modelling study. The challenge of our new wetland model is to represent the hydrological functioning of the various landscape units encountered in those watersheds and their interactions using simple numerical formulations that can be later extended to larger basins such as the Mackenzie river basin. Using observed datasets, the performance of the model to simulate the temporal evolution of hydrological variables such as the water table depth, frost table depth and discharge is assessed.

  5. Ellipticity of Rayleigh waves in basin and hard-rock sites in Northern Italy

    Berbellini, Andrea; Morelli, Andrea; Ferreira, Ana M. G.


    We measure ellipticity of teleseismic Rayleigh waves at 95 seismic stations in Northern Italy, for wave period between 10 and 110 s, using an automatic technique and a large volume of high-quality seismic recordings from over 500 global earthquakes that occurred in 2008-2014. Northern Italy includes a wide range of crustal structures, from the wide and deep Po Plain sedimentary basin to outcropping sedimentary and crystalline rocks in the Northern Apennines and Alps. It thus provides an excellent case for studying the influence of shallow earth structure on polarization of surface waves. The ellipticity measurements show excellent spatial correlation with geological features in the region, such as high ellipticity associated with regions of low seismic velocity in the Po Plain and low ellipticity values in faster, hard rock regions in the Alps and Apennine mountains. Moreover, the observed ellipticity values also relate to the thickness of the basement, as highlighted by observed differences beneath the Alps and the Apennines. Comparison between observations and predicted ellipticity from a reference crustal model of the region show substantial fit, particularly for T ˜ 38 s data. Discrepancy for shorter wave period suggests that slight modifications of the model are needed, and that the ellipticity measurements could help to better constrain the shallow crustal structure of the region. Predictions for the Po Plain are larger than the observations by a factor of four or more and transition from retrograde to prograde Rayleigh wave motion at the surface for periods of T ˜ 10-13 s is predicted for seismic stations in the plain. Analysis of corresponding real data indicates a possible detection of teleseismic prograde particle motion, but the weak teleseismic earthquake signals are mixed with ambient noise signals at the predicted, short, transition periods. Detection of the period of polarity inversion from the joint analysis of earthquake and ambient noise

  6. Ellipticity of Rayleigh waves in basin and hard-rock sites in Northern Italy

    Berbellini, Andrea; Morelli, Andrea; Ferreira, Ana M. G.


    We measure ellipticity of teleseismic Rayleigh waves at 95 seismic stations in Northern Italy, for wave period between 10 s and 110 s, using an automatic technique and a large volume of high-quality seismic recordings from over 500 global earthquakes that occurred in 2008-2014. Northern Italy includes a wide range of crustal structures, from the wide and deep Po Plain sedimentary basin to outcropping sedimentary and cristalline rocks in the Northern Apennines and Alps. It thus provides an excellent case for studying the influence of shallow earth structure on polarisation of surface waves. The ellipticity measurements show excellent spatial correlation with geological features in the region, such as high ellipticity associated with regions of low seismic velocity in the Po Plain and low ellipticity values in faster, hard rock regions in the Alps and Apennine mountains. Moreover, the observed ellipticity values also relate to the thickness of the basement, as highlighted by observed differences beneath the Alps and the Apennines. Comparison between observations and predicted ellipticity from a reference crustal model of the region show substantial fit, particularly for T ˜ 38 s data. Discrepancy for shorter wave period suggests that slight modifications of the model are needed, and that the ellipticity measurements could help to better constrain the shallow crustal structure of the region. Predictions for the Po Plain are larger than the observations by a factor of four or more and transition from retrograde to prograde Rayleigh wave motion at the surface for periods of T ˜ 10-13 s is predicted for seismic stations in the Plain. Analysis of corresponding real data indicates a possible detection of teleseismic prograde particle motion, but the weak teleseismic earthquake signals are mixed with ambient noise signals at the predicted, short, transition periods. Detection of the period of polarity inversion from the joint analysis of earthquake and ambient noise

  7. The Millstone Grit Group (Pennsylvanian) of the Northumberland-Solway Basin and Alston Block of northern England

    Waters, C.N; Millward, D.; C. W. Thomas


    In the Northumberland–Solway Basin and Alston Block of northern England, some aspects of the stratigraphical and sedimentological relationships between the Millstone Grit Group, the Stainmore Formation (Namurian part of the Yoredale Group) and the Westphalian Pennine Coal Measures Group are uncertain. Also, confusion has resulted from discontinuation of Millstone Grit as a formal lithostratigraphical term north of the Stainmore Basin. This paper presents the evidence for, and describes the na...

  8. A long lacustrine record from the Piànico-Sèllere Basin (Middle-Late Pleistocene, Northern Italy)

    A. Moscariello; Ravazzi, C.; Achim Brauer; C. Mangili; Chiesa, S.; Rossi, S.; J.-L. de Beaulieu; M. Reille


    The stratigraphical succession of the Piànico-Sèllere Basin (Northern Italy) represents an exceptionally well preserved sedimentary assemblage which formed in a closed lake basin during the Middle–Upper Pleistocene. These deposits are grouped into the hereby proposed "Piànico Formation". This includes four lacustrine, fine-grained, laminated lithostratigraphical units containing a 10.5 m thick interval of well preserved varved carbonates. The lacustrine units are coeval, and laterally heterop...

  9. Helium Isotope Variations in the Northern Lau and North Fiji Basins

    Lupton, J. E.; Arculus, R. J.; Jenner, F. E.; Evans, L.; Greene, R.


    Recent measurements of submarine basalts from the Northern Lau Basin exhibit a fascinating pattern in the helium isotopes. In particular, basalts along the NW Lau Spreading Center and the Rochambeau Rifts (NWLSC-RR) all have elevated 3He/4He ratios ranging from 11 to 28 Ra, much higher than the MORB-like values of 7 - 9 Ra that might be expected for a typical back-arc spreading center (Lupton et al, GRL 2009) (R = 3He/4He and Ra = Rair = 1.39E-6). This has been interpreted as indicating the presence of a mantle plume component, possibly from the Samoan hotspot, which has somehow intruded into the northern Lau Basin. Furthermore, neon isotopes analyzed in this same suite of basalts exhibit enrichments in 21Ne/22Ne and 20Ne/22Ne distinct from MORB neon and similar to neon isotopes measured in Samoan lavas (Lupton et al., GRL, 2012), further evidence for intrusion of a Samoan plume component. Surprisingly, this hotspot component is only evident along the NWLSC-RR, while samples from seafloor basalts and submarine hydrothermal fluids in the NE Lau Basin have MORB-like values or lower, varying from 6.5 to 8.5 Ra. However, very few samples have been collected to the west of the NWLSC-RR, and the question thus remains as to the origin and extent of this 3He-rich component in the northern Lau Basin. Recently, expedition SS2012 of the R/V Southern Surveyor collected submarine rock samples from the volcanic zones in the northwestern Lau Basin and North Fiji Basin. These samples have 3He/4He ratios ranging from 9.0 up to 14.6 Ra, above the range for normal MORBs. Of particular interest is the zone immediately to the west of the Rochambeau Rifts. Samples from the SE Futuna Volcanic Zone and from the Futuna Spreading Center have 3He/4He varying from 9.2 to 10.6 Ra. Farther west, samples from the West Cikobia Volcanic Zone due north of the Fiji Islands have helium with 9.3 up to 12.2 Ra. Still farther west in the Fiji Basin at 17S, 174E, samples dredged from the NE Fiji Triple

  10. Water masses of the northern part of the Iceland Basin in the late Pleistocene

    Lukashina, N. P.


    A core of bottom sediments AMK-4438 with a length of 320 cm was taken in the North-Eastern part of the Iceland Basin from the depth of 2240 m. The continuous sampling (every 2 cm) made it possible to study the core using the principle of high-resolving paleoceanology. For the stratigraphic partition of the core, we applied the paleotemperature analysis by planktonic foraminifera and carbonate analysis; the distribution of the iceberg rafted debris (IRD) was studied. As a result, nine isotopic stages were distinguished. The change in the complexes of benthic foraminifera indicates that the present-day deepwater circulation in the North-Eastern part of the Iceland Basin had no analogs in earlier glacial periods, including the MIS 5 age. During almost 300 ka, there were relatively warm, rich in nutrients, and poor in oxygen water masses. The formation of the modern Northern-Eastern deep water in the Iceland Basin began in the Bolling-Allerod 14 ka B.P.

  11. Formation Laws of Inorganic Gas Pools in the Northern Jiangsu Basin


    In the Northern Jiangsu basin there are high pure CO2 gas pools, low condensed oil-containing CO2 gas pools, high condensed oil-containing CO2 gas pools and He-containing natural gas pools, with the d 13Cco2 (PDB) values ranging from - 2.87to - 6.50 3He/4He 3.71×10- 6 to 6.42×10- 6, R/Ra 2.64 to 4.5, 40Ar/36Ar 705 to 734, belonging to typical mantle source inorganic gas pools which are related to young magmatic activity. The gas layers occur in two major reservoir-caprock systems, the terrestrial Meso-Cenozoic clastic rock system and the marine Meso-Palaeozoic carbonate rock-clastic rock system. Controlled by the difference in the scale of traps in the two reservoir-caprock systems, large and medium-scale inorganic gas pools are formed in the marine Meso-Palaeozoic Group and only small ones are formed in the terrestrial Meso-Cenozoic strata. Inorganic gas pools in this basin are distributed along the two deep lithospheric faults on the west and south boundaries of the basin. Gas pools are developed at the intersected part of the ENE-trending faults that control the half graben and the E-W tenso-shear faults, mainly distributed near the Es1, Ny1 and Ny2-Q basalt eruption centres.

  12. An isotope hydrochemical approach to understand fluoride release into groundwaters of the Datong Basin, Northern China.

    Su, Chunli; Wang, Yanxin; Xie, Xianjun; Zhu, Yapeng


    The hydrogeochemical and isotopic investigations of high fluoride (up to 8.26 mg L(-1)) groundwater in the Datong Basin, Northern China were carried out in order to evaluate the geochemical controls on fluoride enrichment. The groundwater fluoride concentration tends to increase along with the regional groundwater flow path away from the basin margins, towards the central parts of the basin. Groundwater with high F concentrations has a distinctive major ion chemistry, being generally HCO3(-)-rich, Na-rich, Ca-poor, and having weak alkaline pH values (7.2 to 8.2) and Na-HCO3 waters. These data indicate that variations in the groundwater major ion chemistry and possibly pH, which are controlled by water-rock interaction processes in the aquifer, are important in mobilizing F. Positive correlations between fluoride with lithogenic sodium (LNa) and HCO3(-) in groundwater show that the high fluoride content and alkaline sodic characteristics of groundwater result from dissolution of fluorine-bearing minerals. The occurrence and behavior of fluorine in groundwater are mainly controlled by fluorite precipitation as a function of Ca(2+) concentration. A positive correlation between fluoride and δ(18)O, low F(-)/Cl(-) ratios, and the low tritium level in the fluoride-rich groundwater indicate the effects of long-term water-rock interactions and intensive evapotranspiration. PMID:25743227

  13. Tree-ring based reconstruction of spring hydroclimate variability in the Caucasus

    Martin-Benito, Dario; Köse, Nesibe; Güner, Tuncay; Pederson, Neil


    The Caucasus region has been identified as one of the most prominent biodiversity hotspots in the world. The region experiences recurrent droughts that not only affect natural vegetation but also the agriculturally-based economies in the Caucasus. Across northeastern Turkey and the Caucasus region, instrumental records providing information on climate variability are generally scarce. Thus the magnitude and frequency of past droughts in this biologically important region are less known. Additionally, despite the increase of climate reconstructions in the past decades for many parts of Europe and Asia, relatively little work has been done to understand hydroclimate variability in the Caucasus region. Nearly all efforts in the region have focused on the Mediterranean part of Turkey and the Middle East region. We developed new tree-ring width chronologies from different elevation sites in northeastern Turkey with the goal to reconstruct annually-resolved estimates of temperature and hydroclimate across the region. We developed the first reconstruction of spring hydroclimate variability for the Caucasus and the southeastern Black Sea Region since 1750 CE using a nested procedure. Despite the high mean annual precipitation in the region, our reconstruction accounted for over 45% of May-June precipitation variability from 1925 to 2006. We observed no evidence of a decrease in spring precipitation during the recent decades. However, we do see a decrease in precipitation variability over the last 75 years with respect to previous periods that, at this time, does not appear to be related to sample replication. Although our reconstructed precipitation shows important similarities with previous work from Mediterranean and northern Turkey, we find distinct drought periods are also evident suggesting a wider range of climate dynamics in the broader Black Sea region than what has been previously identified. Distinct episodes of drought at the larger scales could have important

  14. Adaptation to changing water resources in the Ganges basin, northern India

    An ensemble of regional climate model (RCM) runs from the EU HighNoon project are used to project future air temperatures and precipitation on a 25 km grid for the Ganges basin in northern India, with a view to assessing impact of climate change on water resources and determining what multi-sector adaptation measures and policies might be adopted at different spatial scales. The RCM results suggest an increase in mean annual temperature, averaged over the Ganges basin, in the range 1-4 oC over the period from 2000 to 2050, using the SRES A1B forcing scenario. Projections of precipitation indicate that natural variability dominates the climate change signal and there is considerable uncertainty concerning change in regional annual mean precipitation by 2050. The RCMs do suggest an increase in annual mean precipitation in this region to 2050, but lack significant trend. Glaciers in headwater tributary basins of the Ganges appear to be continuing to decline but it is not clear whether meltwater runoff continues to increase. The predicted changes in precipitation and temperature will probably not lead to significant increase in water availability to 2050, but the timing of runoff from snowmelt will likely occur earlier in spring and summer. Water availability is subject to decadal variability, with much uncertainty in the contribution from climate change. Although global social-economic scenarios show trends to urbanization, locally these trends are less evident and in some districts rural population is increasing. Falling groundwater levels in the Ganges plain may prevent expansion of irrigated areas for food supply. Changes in socio-economic development in combination with projected changes in timing of runoff outside the monsoon period will make difficult choices for water managers. Because of the uncertainty in future water availability trends, decreasing vulnerability by augmenting resilience is the preferred way to adapt to climate change. Adaptive policies are

  15. Early life history of the northern pikeminnow in the lower Columbia River basin

    Gadomski, D.M.; Barfoot, C.A.; Bayer, J.M.; Poe, T.P.


    The northern pikeminnow Ptychocheilus oregonensis is a large, native cyprinid in the Columbia River basin that has persisted in spite of substantial habitat alterations. During the months of June to September 1993-1996, we investigated the temporal and spatial patterns of northern pikeminnow spawning, along with describing larval drift and characterizing larval and early juvenile rearing habitats in the lower Columbia River (the John Day and Dalles reservoirs and the free-flowing section downstream of Bonneville Dam) as well as in the lower sections of two major tributaries (the John Day and Deschutes rivers). The density of newly emerged drifting larvae was higher in dam tailraces (a mean of 7.7 larvae/100 m3 in surface tows) than in the lower reservoirs (0.3 larvae/100 m3), indicating that tailraces were areas of more intense spawning. Density was particularly high in the Bonneville Dam tailrace (15.1 larvae/100 m3), perhaps because adult northern pikeminnow are abundant below Bonneville Dam and this is the first tailrace and suitable main-stem spawning habitat encountered during upriver spawning migrations. Spawning also occurred in both of the tributaries sampled but not in a backwater. Spawning in the Columbia River primarily took place during the month of June in 1993 and 1994, when the water temperature rose from 14??C to 18??C, but occurred about 2 weeks later in 1995 and 1996, possibly because of cooler June water temperature (14-15??C) in these years. The period of drift was brief (about 1-3 d), with larvae recruiting to shallow, low-velocity shorelines of main-channel and backwater areas to rear. Larvae reared in greatest densities at sites with fine sediment or sand substrates and moderate- to high-density vegetation (a mean density of 92.1 larvae/10 m3). The success of northern pikeminnow in the Columbia River basin may be partly attributable to their ability to locate adequate spawning and rearing conditions in a variety of main-stem and tributary




    Since the Middle-Late Miocene, the Apennine chain was characterised by the development of several basins. These basins have been alternatively explained as extensional post-orogenic basins or syn-orogenic compressional basins. In this framework, the Pliocene depositional history of the Val d'Orcia Basin (Southern Tuscany) is described, based on a sequence stratigraphic approach. Three depositional sequences (Vd3a-c) have been recognized. The Vd3a sequence records marine ingression and subsequ...

  17. Tectonic stratification and seismicity of the accretionary prism of the Azerbaijani part of Greater Caucasus

    Alizade, Akif; Kangarli, Talat; Aliyev, Fuad


    The Greater Caucasus has formed during last stage of the tectogenesis in a geodynamic condition of the lateral compression, peculiar to the zone pseudo-subduction interaction zone between Northern and Southern Caucasian continental microplates. Its present day structure formed as a result of horizontal movements of the different phases and sub-phases of Alpine tectogenesis (from late Cimmerian to Valakhian), and is generally regarded as zone where, along Zangi deformation, the insular arc formations of the Northern edge of South Caucasian microplate thrust under the Meso-Cenozoic substantial complex contained in the facials of marginal sea of Greater Caucasus. The last, in its turn, has been pushed beneath the North-Caucasus continental margin of the Scythian plate along Main Caucasus Thrust fault. Data collected from the territory of Azerbaijan and its' sector of the Caspian area stands for pseudo-subduction interaction of microplates which resulted in the tectonic stratification of the continental slope of Alpine formations, marginal sea and insular arc into different scale plates of south vergent combined into napping complexes. In the orogeny's present structure, tectonically stratified Alpine substantial complex of the marginal sea of Greater Caucasus bordered by Main Caucasus and Zangi thrusts, is represented by allochthonous south vergent accretionary prism in the front of first deformation with its' root buried under the southern border of Scythian plate. Allocated beneath mentioned prism, the autochthonous bedding is presented by Meso-Cenosoic complex of the Northern flank of the South-Caucasian miroplate, which is in its' turn crushed and lensed into southward shifted tectonic microplates gently overlapping the northern flank of Kura flexure along Ganykh-Ayrichay-Alyat thrust. Data of real-time GPS measurement of regional geodynamics indicates that pseudo-subduction of South Caucasian microplate under the North Caucasian microplate still continues during

  18. Polyphase tectonic subsidence evolution of the Vienna Basin inferred from quantitative subsidence analysis of the northern and central parts

    Lee, Eun Young; Wagreich, Michael


    The Vienna Basin is a tectonically complex Neogene basin situated at the Alpine-Carpathian transition. This study analyzes a detailed quantification of subsidence in the northern and central parts of the Vienna Basin to understand its tectonic subsidence evolution. About 200 wells were used to arrange stratigraphic setting, and wells reaching the pre-Neogene basement were analyzed for subsidence. To enhance the understanding of the regional subsidences, the wells were sorted into ten groups based on their position on major fault blocks. In the Early Miocene, subsidence was slow and along E-W to NE-SW trending axis, indicating the development of thrust-controlled piggyback basins. During the late Early Miocene data show abruptly increasing subsidence, making the initiation of the Vienna pull-apart basin system. From the Middle Miocene, the tectonic subsidence curves show regionally different patterns. The tectonic subsidence during the Middle Miocene varies laterally across the Vienna Basin, and the differential subsidence can be related to the changing tensional regime of weakening transtension and strengthening extension toward the late Middle Miocene. From the late Middle Miocene to the Late Miocene, the tectonic subsidence occurred dominantly along the regional active faults, and corresponds to the axis of E-W trending extension of the western parts of the Pannonian Basin system. In the Quaternary the Vienna Basin has been reactivated, and resulted in subsidence along the NE-SW trending Vienna Basin transfer fault system.

  19. A Very Large Population of Likely Buried Impact Basins in the Northern Lowlands of Mars Revealed by MOLA Data

    Frey, H. V.; Shockey, K. M.; Frey, E. L.; Roark, J. H.; Sakimoto, S. E. H.


    High resolution Mars Orbiter Laser Altimeter (MOLA) data have revealed a large number of subdued quasi-circular depressions (QCDs) >50 km diameter in the northern lowlands of Mars which are generally not visible in Viking imagery and which may be buried ancient impact basins. Additional information is contained in the original extended abstract.

  20. Facies-controlled volcanic reservoirs of northern Songliao Basin, NE China


    Volcanic rocks of the late Mesozoic are very important reservoirs for the commercial natural gases including hydrocarbon, carbon dioxide and rare gases in the northern Songliao Basin. The reservoir volcanic rocks include rhyolite,andesite, trachyte, basalt and tuff. Facies of the volcanic rocks can be classified into 5 categories and 15 special types.Porosity and permeability of the volcanic reservoirs are facies-controlled. Commercial reservoirs were commonly found among the following volcanic subfacies: volcanic neck (Ⅰ1), underground-explosive breccia (Ⅰ3), pyroclastic-bearing lava flow (Ⅱ3), upper effusive (Ⅲ3) and inner extrusive ones (Ⅳ1). The best volcanic reservoirs are generally evolved in the interbedded explosive and effusive volcanics. Rhyolites show in general better reservoir features than other types of rocks do.

  1. New GMP Models for Caucasus Region

    Jorjiashvili, N.; Godoladze, T.; Tvaradze, N.; Tumanova, N.


    The Caucasus is a region of numerous natural hazards and ensuing disasters. Analysis of the losses due to past disasters indicates those most catastrophic in the region have historically been due to strong earthquakes. Estimation of expected ground motion is a fundamental earthquake hazard assessment. The most commonly used parameter for attenuation relation is peak ground acceleration because this parameter gives useful information for Seismic Hazard Assessment. Thus, many peak ground acceleration attenuation relations have been developed by different authors. However, a few attenuation relations were developed for Caucasus region: Ambraseys et al. (1996,2005) which were based on entire European region and they were not focused locally on Caucasus Region, Smit that was based on a small amount of acceleration data that really is not enough. Since 2003 construction of Georgian Digital Seismic Network has started with the help of number of International organizations, Projects and Private companies. In this study new GMP models are obtained based on new data from Georgian seismic network and also from neighboring countries. Estimation of models is obtained by classical, statistical way, regression analysis. Also site ground conditions are considered because the same earthquake recorded at the same distance may cause different damage according to ground conditions. Thus, this parameter is emphasized in the present study. Here it must be mentioned that in previous model which only one was done for Caucasus Region (Smit et. al., 2000) local conditions were not considered. Thus, it is an advantage of models from this study.

  2. Hydrogeochemistry of high-fluoride groundwater at Yuncheng Basin, northern China.

    Li, Chengcheng; Gao, Xubo; Wang, Yanxin


    Hydrogeochemical and environmental isotope methods were integrated to delineate the spatial distribution and enrichment of fluoride in groundwater at Yuncheng Basin in northern China. One hundred groundwater samples and 10 Quaternary sediment samples were collected from the Basin. Over 69% of the shallow groundwater (with a F(-) concentration of up to 14.1mg/L), 44% of groundwater samples from the intermediate and 31% from the deep aquifers had F(-) concentrations above the WHO provisional drinking water guideline of 1.5mg/L. Groundwater with high F(-) concentrations displayed a distinctive major ion chemistry: Na-rich and Ca-poor with a high pH value and high HCO3(-) content. Hydrochemical diagrams and profiles and hydrogen and oxygen isotope compositions indicate that variations in the major ion chemistry and pH are controlled by mineral dissolution, cation exchange and evaporation in the aquifer systems, which are important for F(-) mobilization as well. Leakage of shallow groundwater and/or evaporite (gypsum and mirabilite) dissolution may be the major sources for F(-) in groundwater of the intermediate and deep aquifers. PMID:25478652

  3. Arsenic release by indigenous bacteria Bacillus cereus from aquifer sediments at Datong Basin, northern China

    Xie, Zuoming; Wang, Yanxin; Duan, Mengyu; Xie, Xianjun; Su, Chunli


    Endemic arsenic poisoning due to long-term drinking of high arsenic groundwater has been reported in Datong Basin, northern China. To investigate the effects of microbial activities on arsenic mobilization in contaminated aquifers, Bacillus cereus ( B. cereus) isolated from high arsenic aquifer sediments of the basin was used in our microcosm experiments. The arsenic concentration in the treatment with both bacteria and sodium citrate or glucose had a rapid increase in the first 18 d, and then, it declined. Supplemented with bacteria only, the concentration could increase on the second day. By contrast, the arsenic concentration in the treatment supplemented with sodium citrate or glucose was kept very low. These results indicate that bacterial activities promoted the release of arsenic in the sediments. Bacterial activities also influenced other geochemical parameters of the aqueous phase, such as pH, Eh, and the concentrations of dissolved Fe, Mn, and Al that are important controls on arsenic release. The removal of Fe, Mn, and Al from sediment samples was observed with the presence of B. cereus. The effects of microbial activities on Fe, Mn, and Al release were nearly the same as those on As mobilization. The pH values of the treatments inoculated with bacteria were lower than those without bacteria, still at alkaline levels. With the decrease of Eh values in treatments inoculated with bacteria, the microcosms became more reducing and are thus favorable for arsenic release.

  4. Using Diverse Data Types to Calibrate a Watershed Model of the Trout Lake Basin, Northern Wisconsin

    Hunt, R. J.; Feinstein, D. T.; Pint, C. D.; Anderson, M. P.


    As part of the USGS Water, Energy, and Biogeochemical Budgets project and NSF Long-Term Ecological Research work, a parameter estimation code was used to calibrate a deterministic groundwater flow model of the Trout Lake Basin in northern Wisconsin. Observations included traditional calibration targets (head, lake stage, and baseflow observations) as well as unconventional targets such as groundwater flows to and from lakes, depth of a lake plume, and time of travel. The unconventional data types were important for parameter estimation convergence and allowed the development of a more parameterized model. Independent estimates of groundwater inflow to lakes were most important for constraining lakebed leakance, and the depth of the lake plume was important for determining hydraulic conductivity and conceptual aquifer layering. The most important target, however, was a conventional regional baseflow target that was important for correctly distributing flow between sub-basins and the regional system. The use of parameter estimation: 1) facilitated the calibration process by providing a quantitative assessment of the model's ability to match disparate observed data types; and 2) provided a best fit for the particular model conceptualization. The model calibration required the use of a "universal" parameter estimation code in order to include all types of observations in the objective function. The methods described here help address issues of watershed complexity and non-uniqueness common to deterministic watershed models.

  5. Crustal Structure Improvement for the Caucasus Region

    Tumanova, N.; Godoladze, T.; Gok, R.; Dreger, D. S.


    The Caucasus is a tectonically active and structurally complex region. The crustal and upper mantle velocities show great heterogeneity and the regional phases display significant variability in both amplitude and travel time. Existing regional velocity and attenuation models fail to capture the complexity of the region, and the extent of the variability is not well quantified. In the last eight years, a large number of digital stations, both broad-band and short-period have been installed in this region. The southern Caucasus countries (Armenia, Azerbaijan and Georgia) have a strongcollaboration to share the data from their national networks through onlinedata exchange. Each country has access to all the available waveform data for use it in scientific research. Utilizing the newly available digital data we have developed an improved seismic velocity model and crustal of the Caucasus. The data from national seismic networks of Georgia, Azerbaijan, and Armenia were analyzed and the velocity model was developed using joint inversion of teleseismic receiver functions and surface waves. We then calculated a forward waveform model of the seismic sources of the Caucasus, calibrating the existing velocity models, and improving the understanding of regional phase propagation in this complex region. Love and Rayleigh wave surface waves group and phase dispersion curves were derived from regional and teleseismic events. The stacked receiver functions and surface wave dispersion curves were jointly inverted to yield the absolute shear wave velocity to a depth of 100-120 km at each station. The depth of major discontinuities (sediment/basement, crust/mantle, and lithosphere/aesthenosphere) were inferred from the velocity/depth profiles at each station. In addition, we performed a local tomography study, based on data from several strong events recorded on temporal networks deployed throughout the southern Caucasus during the last few years ( Racha 2009. Javakheti 2010

  6. Land cover changes associated with recent energy development in the Williston Basin; Northern Great Plains, USA.

    Preston, Todd M; Kim, Kevin


    The Williston Basin in the Northern Great Plains has experienced rapid energy development since 2000. To evaluate the land cover changes resulting from recent (2000-2015) development, the area and previous land cover of all well pads (pads) constructed during this time were determined, the amount of disturbed and reclaimed land adjacent to pads was estimated, land cover changes were analyzed over time for three different well types, and the effects from future development were predicted. The previous land cover of the 12,990ha converted to pads was predominately agricultural (49.5%) or prairie (47.4%) with lesser amounts of developed (2.3%), aquatic (0.5%), and forest (0.4%). Additionally, 12,121ha has likely been disturbed and reclaimed. The area required per gas well remained constant through time while the land required per oil well increased initially and then decreased as development first shifted from conventional to unconventional drilling and then to multi-bore pads. For non-oil-and-gas wells (i.e. stratigraphic test wells, water wells, and injection wells), the area per well increased through time likely due to increased produced water disposal requirements. Future land cover change is expected to be 2.7 times greater than recent development with much of the development occurring in five counties in the core Bakken development area. Direct land cover change and disturbance from recent and expected development are predicted to affect 0.4% of the landscape across the basin; however, in the core Bakken development area, 2.3% of the landscape will be affected including 2.1% of the remaining grassland. Although future development will result in significant land cover change, evolving industry practices and proactive siting decisions, such as development along energy corridors and placing pads in areas previously altered by human activity, have the potential to reduce the ecological effects of future energy development in the Williston Basin. PMID:27318516

  7. Source identification of fine-grained suspended sediment in the Kharaa River basin, northern Mongolia

    Fine sediment inputs into river systems can be a major source of nutrients and heavy metals and have a strong impact on water quality and ecosystem functions of rivers and lakes, including those in semiarid regions. However, little is known to date about the spatial distribution of sediment sources in most large scale river basins in Central Asia. Accordingly, a sediment source fingerprinting technique was used to assess the spatial sources of fine-grained (< 10 μm) sediment in the 15 000 km2 Kharaa River basin in northern Mongolia. Variation in geochemical composition (e.g. in Ti, Sn, Mo, Mn, As, Sr, B, U, Ca and Sb) was used for sediment source discrimination with geochemical composite fingerprints based on Genetic Algorithm (GA)-driven Discriminant Function Analysis, the Kruskal–Wallis H-test and Principal Component Analysis. All composite fingerprints yielded a satisfactory GOF (> 0.97) and were subsequently used for numerical mass balance modelling with uncertainty analysis. The contributions of the individual sub-catchment spatial sediment sources varied from 6.4% (the headwater sub-catchment of Sugnugur Gol) to 36.2% (the Kharaa II sub-catchment in the middle reaches of the study basin), generally showing higher contributions from the sub-catchments in the middle, rather than the upstream, portions of the study area. The importance of river bank erosion is shown to increase from upstream to midstream tributaries. The source tracing procedure provides results in reasonable accordance with previous findings in the study region and demonstrates the applicability and associated uncertainties of the approach for fine-grained sediment source investigation in large scale semi-arid catchments. - Highlights: • Applied statistical approach for selecting composite fingerprints in Mongolia. • Geochemical fingerprinting for the definition of source areas in semiarid catchment. • Test of applicability of sediment sourcing in large scale semi-arid catchments.

  8. Source identification of fine-grained suspended sediment in the Kharaa River basin, northern Mongolia

    Theuring, Philipp [Department of Aquatic Ecosystem Analysis and Management — ASAM, Helmholtz Centre for Environmental Research — UFZ, Brückstrasse 3a, D-39114 Magdeburg (Germany); Collins, Adrian L. [Sustainable Soils and Grassland Systems Department, Rothamsted Research, North Wyke, Okehampton, Devon EX20 2SB (United Kingdom); Rode, Michael [Department of Aquatic Ecosystem Analysis and Management — ASAM, Helmholtz Centre for Environmental Research — UFZ, Brückstrasse 3a, D-39114 Magdeburg (Germany)


    Fine sediment inputs into river systems can be a major source of nutrients and heavy metals and have a strong impact on water quality and ecosystem functions of rivers and lakes, including those in semiarid regions. However, little is known to date about the spatial distribution of sediment sources in most large scale river basins in Central Asia. Accordingly, a sediment source fingerprinting technique was used to assess the spatial sources of fine-grained (< 10 μm) sediment in the 15 000 km{sup 2} Kharaa River basin in northern Mongolia. Variation in geochemical composition (e.g. in Ti, Sn, Mo, Mn, As, Sr, B, U, Ca and Sb) was used for sediment source discrimination with geochemical composite fingerprints based on Genetic Algorithm (GA)-driven Discriminant Function Analysis, the Kruskal–Wallis H-test and Principal Component Analysis. All composite fingerprints yielded a satisfactory GOF (> 0.97) and were subsequently used for numerical mass balance modelling with uncertainty analysis. The contributions of the individual sub-catchment spatial sediment sources varied from 6.4% (the headwater sub-catchment of Sugnugur Gol) to 36.2% (the Kharaa II sub-catchment in the middle reaches of the study basin), generally showing higher contributions from the sub-catchments in the middle, rather than the upstream, portions of the study area. The importance of river bank erosion is shown to increase from upstream to midstream tributaries. The source tracing procedure provides results in reasonable accordance with previous findings in the study region and demonstrates the applicability and associated uncertainties of the approach for fine-grained sediment source investigation in large scale semi-arid catchments. - Highlights: • Applied statistical approach for selecting composite fingerprints in Mongolia. • Geochemical fingerprinting for the definition of source areas in semiarid catchment. • Test of applicability of sediment sourcing in large scale semi-arid catchments

  9. Crustal structure beneath the Northern Transantarctic Mountains and Wilkes Subglacial Basin: Implications for tectonic origins

    Hansen, Samantha E.; Kenyon, Lindsey M.; Graw, Jordan H.; Park, Yongcheol; Nyblade, Andrew A.


    The Transantarctic Mountains (TAMs) are the largest noncollisional mountain range on Earth. Their origin, as well as the origin of the Wilkes Subglacial Basin (WSB) along the inland side of the TAMs, has been widely debated, and a key constraint to distinguish between competing models is the underlying crustal structure. Previous investigations have examined this structure but have primarily focused on a small region of the central TAMs near Ross Island, providing little along-strike constraint. In this study, we use data from the new Transantarctic Mountains Northern Network and from five stations operated by the Korea Polar Research Institute to investigate the crustal structure beneath a previously unexplored portion of the TAMs. Using S wave receiver functions and Rayleigh wave phase velocities, crustal thickness and average crustal shear velocity (V>¯s) are resolved within ±4 km and ±0.1 km/s, respectively. The crust thickens from ~20 km near the Ross Sea coast to ~46 km beneath the northern TAMs, which is somewhat thicker than that imaged in previous studies beneath the central TAMs. The crust thins to ~41 km beneath the WSB. V>¯s ranges from ~3.1-3.9 km/s, with slower velocities near the coast. Our findings are consistent with a flexural origin for the TAMs and WSB, where these features result from broad flexure of the East Antarctic lithosphere and uplift along its western edge due to thermal conduction from hotter mantle beneath West Antarctica. Locally, thicker crust may explain the ~1 km of additional topography in the northern TAMs compared to the central TAMs.

  10. The eastern Black Sea-Caucasus region during the Cretaceous: New evidence to constrain its tectonic evolution

    Sosson, Marc; Stephenson, Randell; Sheremet, Yevgeniya; Rolland, Yann; Adamia, Shota; Melkonian, Rafael; Kangarli, Talat; Yegorova, Tamara; Avagyan, Ara; Galoyan, Ghazar; Danelian, Taniel; Hässig, Marc; Meijers, Maud; Müller, Carla; Sahakyan, Lilit; Sadradze, Nino; Alania, Victor; Enukidze, Onice; Mosar, Jon


    We report new observations in the eastern Black Sea-Caucasus region that allow reconstructing the evolution of the Neotethys in the Cretaceous. At that time, the Neotethys oceanic plate was subducting northward below the continental Eurasia plate. Based on the analysis of the obducted ophiolites that crop out throughout Lesser Caucasus and East Anatolides, we show that a spreading center (AESA basin) existed within the Neotethys, between Middle Jurassic and Early Cretaceous. Later, the spreading center was carried into the subduction with the Neotethys plate. We argue that the subduction of the spreading center opened a slab window that allowed asthenospheric material to move upward, in effect thermally and mechanically weakening the otherwise strong Eurasia upper plate. The local weakness zone favored the opening of the Black Sea back-arc basins. Later, in the Late Cretaceous, the AESA basin obducted onto the Taurides-Anatolides-South Armenia Microplate (TASAM), which then collided with Eurasia along a single suture zone (AESA suture).

  11. Hydrothermal recrystallization of the Lower Ordovician dolomite and its significance to reservoir in northern Tarim Basin


    Discovered in S15 and some other wells, the Lower Ordovician in the northern Tarim Basin consists mainly of brown gray-dark gray very fine-fine crystalline dolomite, with a minor portion of locally light gray-white medium-coarse crystalline dolomite. Silicification can be observed in the medium-coarse dolomite, and some euhedral drusy quartz can also be found in pores and fractures of the dolomite. The homogenization temperature of the fluid inclusions in the medium-coarse dolomite is between 110 and 200°C with maximum between 140 and 190°C, and the salinity is between 10.7 and 18.5 wt.% NaCl Eq. The homogenization temperature and salinity of the fluid inclusions in the medium-coarse dolomite are similar to those in the drusy quartz. Compared with the very fine-fine dolomite, the medium-coarse phase contains relatively high Fe and Mn. The average concentration of FeO and MnO in the medium-coarse dolomite is 1.917% and 0.323%, respectively. The medium-coarse dolomite has a remarkable negative Eu anomaly, consistent with the REE pattern of the intermediate-felsic igneous rocks in the Tarim Basin. The oxygen isotopic composition of the medium-coarse dolomite is relatively lighter than that of the very fine-fine dolomite. The δ18OPDB values of the medium-coarse dolomite are between -10.35‰ and -7.31‰. The δ18OSMOW values of the fluid associated with the medium-coarse dolomite can be calculated according to homogenization temperature and oxygen isotope fractionation factor between dolomite and fluid, and the calculated values are between +4‰ and +10‰, consistent with those of the hydrothermal fluid. The medium-coarse dolomite has relatively high 87Sr/86Sr ratios as well, indi- cating an origin associated with intermediate-felsic igneous rock. The homogenization temperature, element composition, REE pattern, oxygen and strontium isotopes demonstrate that the medium-coarse dolomite is the result of recrystallization of very fine-fine dolomite under

  12. Low palaeoelevation of the northern Lhasa terrane during late Eocene: Fossil foraminifera and stable isotope evidence from the Gerze Basin

    Wei, Yi; Zhang, Kexin; Garzione, Carmala N.; Xu, Yadong; Song, Bowen; Ji, Junliang


    The Lhasa terrane is a key region for understanding the paleoelevation of the southern Tibetan Plateau after India-Asia collision. The Gerze Basin, located in the northern part of the Lhasa terrane, is a shortening-related basin. We discovered Lagena laevis (Bandy) fossils in upper Eocene strata of the Gerze Basin. This type of foraminifera is associated with lagoon and estuarine environments, indicating that the northern part of the Lhasa terrane was near sea level during the late Eocene. We speculate that these foraminifera were transported inland by storm surges to low elevation freshwater lakes during times of marine transgressions. This inference is consistent with the relatively positive δ18O values in carbonate from the same deposits that indicate low palaeoelevations close to sea level. Considering the palaeoelevation results from the nearby Oligocene basins at a similar latitude and the volcanic history of the Lhasa terrane, we infer that large-magnitude surface uplift of the northern Lhasa terrane occurred between late Eocene and late Oligocene time. PMID:27272610

  13. Radionuclide levels in fish from Lake Athabasca February 1993. Northern River Basins Study project report no.26

    The Northern River Basins Study was initiated through the 'Canada-Alberta-Northwest Territories Agreement Respecting the Peace-Athabasca-Slave River Basin Study, Phase II - Technical Studies' which was signed September 27, 1991. The purpose of the study is to understand and characterize the cumulative effects of development on the water and aquatic environment of the Study Area by coordinating with existing programs and undertaking appropriate new technical studies. This publication reports the method and findings of particular work conducted as part of the Northern River Basins Study. As such, the work was governed by a specific terms of reference and is expected to contribute information about the Study Area within the context of the overall study as described by the Study Final Report. This report has been reviewed by the Study Science Advisory Committee in regards to scientific content and has been approved by the Study Board of Directors for public release. It is explicit in the objectives of the Study to report the results of technical work regularly to the public. This objective is served by distributing project reports to an extensive network of libraries, agencies, organizations and interested individuals and by granting universal permission to reproduce the material. This report contains referenced data obtained from external to the Northern River Basins Study. Individuals interested in using external data must obtain permission to do so from the donor agency. (author). 47 refs., 9 tabs., 2 figs

  14. Seismic sequence and depositional evolution of slope basins in mid-northern margin of the South China Sea

    LI Mingbi; JIN Xianglong; LI Jiabiao; DING Weiwei; FANG Yinxia; LIU Jianhua; TANG Yong


    As one of the biggest marginal seas in the western Pacific margin,the South China Sea (SCS) experienced continental riffing and seafloor spreading during the Cenozoic.The northern continental margin of the SCS is classified as a passive continental margin.However,its depositional and structural evolution remains controversial,especially in the deep slope area.The lack of data hindered the correlation between continental shelf and oceanic basin,and prevented the establishment of sequence stratigraphic frame of the whole margin.The slope basins in the mid-northern margin of SCS developed in the Cenozoic;the sediments and basin infill recorded the geological history of the continental margin and the SCS spreading.Using multi-channel seismic dataset acquired in three survey cruises during 1987 to 2004,combined with the data of ODP Leg 184 core and industrial wells,we carried out the sequence stratigraphic division and correlation of the Cenozoic in the middle-northern margin of SCS with seismic profiles and sedimentary facies.We interpreted the seismic reflection properties including continuity,amplitude,frequency,reflection terminals,and 15 sequence boundaries of the Cenozoic in the study area,and correlated the well data in geological age.The depositional environment changed from river and lake,shallow bay to open-deep sea,in correspondence to tectonic events of syn-rifting,early drifting,and late drifting stages of basin evolution.

  15. Low palaeoelevation of the northern Lhasa terrane during late Eocene: Fossil foraminifera and stable isotope evidence from the Gerze Basin

    Wei, Yi; Zhang, Kexin; Garzione, Carmala N.; Xu, Yadong; Song, Bowen; Ji, Junliang


    The Lhasa terrane is a key region for understanding the paleoelevation of the southern Tibetan Plateau after India-Asia collision. The Gerze Basin, located in the northern part of the Lhasa terrane, is a shortening-related basin. We discovered Lagena laevis (Bandy) fossils in upper Eocene strata of the Gerze Basin. This type of foraminifera is associated with lagoon and estuarine environments, indicating that the northern part of the Lhasa terrane was near sea level during the late Eocene. We speculate that these foraminifera were transported inland by storm surges to low elevation freshwater lakes during times of marine transgressions. This inference is consistent with the relatively positive δ18O values in carbonate from the same deposits that indicate low palaeoelevations close to sea level. Considering the palaeoelevation results from the nearby Oligocene basins at a similar latitude and the volcanic history of the Lhasa terrane, we infer that large-magnitude surface uplift of the northern Lhasa terrane occurred between late Eocene and late Oligocene time.

  16. Oligocene-Miocene deformational and depositional history of the Andean hinterland basin in the northern Altiplano plateau, southern Peru

    Perez, Nicholas D.; Horton, Brian K.


    Cenozoic basin fill of the northern Altiplano plateau records the tectonic development of the flanking Western Cordillera magmatic arc and Eastern Cordillera fold-thrust belt. The Ayaviri hinterland basin of southern Peru contains a ~2300 m thick succession of fluvial sandstones and overbank siltstones (upper Oligocene Puno Group and lower Miocene lower Tinajani Formation) capped by ~400 m of alluvial fan conglomerates (middle Miocene upper Tinajani Formation). New U-Pb zircon chronostratigraphic constraints from ~30 to 15 Ma yield sediment accumulation rates of 110-660 m/Myr. Newly dated growth strata highlight the genetic role played by thrust displacement in basin evolution. A several phase accumulation history derived from chronostratigraphic, provenance, and structural data reveals Oligocene basin filling by fluvial sand and mud that changes provenance from Western Cordillera Mesozoic-Cenozoic volcanic rocks to Paleozoic-Mesozoic Eastern Cordillera sedimentary rocks driven by deformation along the southwest directed, northeastern basin margin Ayaviri thrust at 28-26 Ma. Continued early Miocene fluvial deposition was sourced solely from the Eastern Cordillera. An abrupt middle Miocene shift to coarse alluvial fan deposition sourced from the Western Cordillera was driven by out-of-sequence deformation along the northeast directed, southwestern basin margin Pasani thrust at 18-16 Ma. This northern Altiplano out-of-sequence deformation was coincident with increased Eastern and Western Cordillera exhumation and thrusting and may be symptomatic of changes in critical wedge dynamics. The overall record of basin sedimentation and syndepositional fold-thrust deformation emphasizes the role of regional shortening in governing crustal thickening and basin evolution in the central Andes during the Oligocene to Miocene.

  17. New seismo-stratigraphic data of the Volturno Basin (northern Campania, Tyrrhenian margin, southern Italy: implications for tectono-stratigraphy of the Campania and Latium sedimentary basins

    Ennio Marsella


    Full Text Available A geological section of the Volturno Basin (northern Campania, continental margin, Italy has been constructed based on new multi-channel seismic data, to show the stratigraphic relationships between the filling in the Quaternary basin and the Meso-Cenozoic acoustic basement. The new seismic sections presented here outline the underlying structures of the basin and their relationships to the filling in the Quaternary basin. Deep exploration wells in Campania and Latium on the Tyrrhenian margin have gathered litho-stratigraphic and commercial multi-channel seismic data that can be used for better integration of the geological data for the area under study. The trending of the seismic units is controlled by the Massico Structural High, which forms the boundary of the Volturno Basin towards the north-west. This produces a geometry that is characteristic of a fan complex, with NE-SW trending. This qualitative calibration of the seismic sequences that fill the sedimentary basin was carried out through the litho-stratigraphic data of the «Castelvolturno 2» well, which highlights the pyroclastic layers and conglomeratic strata of the lagoon and delta environments as they evolve upwards towards marine sediments. Seismo-stratigraphic analysis shows the complex depositional geometries of the filling in the Volturno Basin, which overlie the Meso-Cenozoic carbonatic basement and the related flysch deposits. Coupled with regional geological evidence, the data interpretation here suggests that the Volturno Basin represents a half-graben structure that is characterized by down-thrown blocks along normal faults.

  18. ITCZ-monsoonal association during the last glacial (Cariaco Basin, Northern Arabian Sea)

    Deplazes, G.; Haug, G. H.; Lueckge, A.


    The anoxic Cariaco Basin on the northern shelf of Venezuela preserves detailed records of past tropical climate variability. The sediment formation in this basin is controlled by the migration of the Atlantic Intertropical Convergence Zone (ITCZ) and the corresponding rain belt and trade winds. In the oxygen minimum zone off Pakistan in the northeastern Arabian Sea sediment archives of low-latitude monsoonal climate are preserved. In this study sediments from the two settings that cover the last 80,- to 110,000 years were analysed. Sediment color analysis resulted in reflectance records with a down to annual resolution. An age model was set up by correlation of these records to the δ18O record of Greenland ice (NGRIP). The major element chemistry of the sediments was analysed with X-ray fluorescence scanning. The new high resolution proxy records indicate an unbroken association between warm climate conditions over Greenland, a northerly position of the Atlantic Intertropical Convergence Zone, and a strong Indian summer monsoon since the last glacial. The tight coupling is explained by a dominant role of the North Atlantic that is communicated largely through the atmosphere. New insights of dynamical mechanisms arise from comparison of individual Dansgaard-Oeschger events. The tropical records and the Greenland δ18O record show both an abrupt change at the beginning of an interstadial. The δ18O of Greenland ice peaks early in the interstadials and then decreases more or less constantly toward stadial values. However, the tropical records have a tendency to maintain dark interstadial color on a similar level over several centuries. The following centennial-scale lightening toward the next stadial appears to be delayed compared to the δ18O ice record. This “resistance” of the tropics to the interstadial-stadial transitions suggests a threshold response of the tropics to North Atlantic cooling.

  19. Development of Overpressure in the Tertiary Damintun Depression, Liaohe Basin, Northern China

    YE Jiaren; HAO Fang; CHEN Jianyu


    The Damintun depression is one of the four depressions in the Liaohe basin in northern China, and is a rift basin developed in the Paleogene. This paper discusses in detail the characteristics of pressure and fluid potential of the Damintun depression based on a synthesis of the data from boreholes, well tests and seismic surveys. Data from sonic logs, well tests and seismic velocity measurements are used to study the pressure characteristics of the areas. From the sonic log data, shales can be characterized as normally pressured, slightly overpressured or highly overpressured; from the well test data, the pressure-depth gradient in oil-producing intervals implies hydrostatic pressure in general. Most seismic profiles in the Damintun depression are of sufficiently high quality for seismic velocities to be measured. The fluid pressures, excess pressures and pressure coefficients in 47 representative seismic profiles are predicted using formula calculation methods, and further transformed to fluid potentials. The resultant pressure profiles show normal pressure, moderate overpressure and intense overpressure increasing with depth. The pressure evolution can be divided into three stages as initial generation, partial dissipation and re-accumulation. Fluid potential is the principal factor controlling hydrocarbon migration in a reservoir. Its distribution varies with depth; above the T4 interface a gravity-flow dominates, whereas beneath it a compaction flow dominates. The development of overpressure in the Damintun depression has a crucial influence on the distribution of fluid potentials, which agrees with that of overpressure in general. The results of the fluid potential analysis indicate that the areas of Dongshenpu-Xinglongpu and the southwestern part of the depression are most favorable for hydrocarbon migration and accumulation.

  20. Effects of precipitation and potential evaporation on actual evapotranspiration over the Laohahe basin, northern China

    Liu, Y.; Ren, L.; Yang, X.; Ma, M.; Yuan, F.; Jiang, S.


    Problems associated with water scarcity are facing new challenges under the climate change. As one of main consumptions in water cycle on the Earth, evapotranspiration plays a crucial role in regional water budget. In this paper, we employ two methods, i.e. hydrological sensitivity analysis and hydrological model simulation, to investigate the effect of climate variability and climatic change on actual evapotranspiration (Ea) within the Laohahe basin during 1964-2009. Calibrations of the two methods are firstly conducted during the baseline period (1964-1979), then with the two benchmarked models, simulations in climatic change duration (1980-2009) are further conducted and quantitative assessments on climatic change-induced variation of Ea are analysed accordingly. The results show that affected by combined impacts of decreased precipitation and potential evapotranspiration, variation of annual Ea in most sub-catchments suffer a downward trend during 1980-2009, with a higher descending rate in northern catchments. At decadal scale, Ea shows significant oscillation in accordance with precipitation patterns. Northern catchments generally suffer more decadal Ea changes than southern catchments, implying the impact of climatic change on decadal Ea is more intense in semi-arid areas than that in semi-humid regions. For whole changed durations, a general 0-20 mm reduction of Ea is found in most parts of studied region. For this water-limited region, Ea shows higher sensitivity to precipitation than to potential evaporation, which confirms the significant role of precipitation in controlling Ea patterns, whereas the impact of potential evapotranspiration variation would be negligible.

  1. High resolution sequence stratigraphic analysis of the Late Miocene Abu Madi Formation, Northern Nile Delta Basin

    Sarhan, Mohammad Abdelfattah


    Abu Madi Formation represents the Upper Miocene Messinian age in the Nile Delta basin. It consists mainly of sandstones and shale intercalations and because of its richness in hydrocarbon, it has been subdivided by the petroleum companies into Level-I, Level-II and Level-III, respectively according to the increase in the sandstone to the shale ratio. The Miocene cycle in the northern subsurface section of the Nile Delta encompasses three main formations namely from the base; Sidi Salim formation, Qawasim Formation and Abu Madi Formation at the top. The high resolution sequence stratigraphic analysis, using gamma ray responses, has been done for the Late Miocene formation in the northern part of the Nile delta subsurface section. For this purpose, the gamma-ray logs of ten deep wells, arranged in four cross-sections trending in almost north-south direction throughout the northern region of the Nile Delta, were analyzed. The analysis has revealed that the interpreted 4th order depositional cycles within Abu Madi Formation display great variations in both number and gamma ray responses in each investigated well, and cannot be traced laterally, even in the nearest well. These variations in the interpreted 4th order depositional sequences could be attributed to the presence of normal faults buried in the inter-area laying between the investigated wells. This finding matches with the conclusion of that Abu Madi Formation represents a part of the Upper Miocene Nile Delta syn-rift megasequence, developed during the Upper Miocene rift phase of the Red Sea - Gulf of Suez province in Egypt. Accordingly, in the sequence stratigraphic approach, the depositional history of Abu Madi Formation was strongly overprinted by the tectonic controls rather than the relative sea-level changes which are assumed to be of a secondary influence. Regarding the hydrocarbon aspects of the Abu Madi Formation, the present work recommends to direct the drilling efforts into the stratigraphic traps

  2. Peat accumulation in drained thermokarst lake basins in continuous, ice-rich permafrost, northern Seward Peninsula, Alaska

    Jones, Miriam C.; Grosse, Guido; Jones, Benjamin M.; Anthony, Katey Walter


    Thermokarst lakes and peat-accumulating drained lake basins cover a substantial portion of Arctic lowland landscapes, yet the role of thermokarst lake drainage and ensuing peat formation in landscape-scale carbon (C) budgets remains understudied. Here we use measurements of terrestrial peat thickness, bulk density, organic matter content, and basal radiocarbon age from permafrost cores, soil pits, and exposures in vegetated, drained lake basins to characterize regional lake drainage chronology, C accumulation rates, and the role of thermokarst-lake cycling in carbon dynamics throughout the Holocene on the northern Seward Peninsula, Alaska. Most detectable lake drainage events occurred within the last 4,000 years with the highest drainage frequency during the medieval climate anomaly. Peat accumulation rates were highest in young (50–500 years) drained lake basins (35.2 g C m−2 yr−1) and decreased exponentially with time since drainage to 9 g C m−2 yr−1 in the oldest basins. Spatial analyses of terrestrial peat depth, basal peat radiocarbon ages, basin geomorphology, and satellite-derived land surface properties (Normalized Difference Vegetation Index (NDVI); Minimum Noise Fraction (MNF)) from Landsat satellite data revealed significant relationships between peat thickness and mean basin NDVI or MNF. By upscaling observed relationships, we infer that drained thermokarst lake basins, covering 391 km2 (76%) of the 515 km2 study region, store 6.4–6.6 Tg organic C in drained lake basin terrestrial peat. Peat accumulation in drained lake basins likely serves to offset greenhouse gas release from thermokarst-impacted landscapes and should be incorporated in landscape-scale C budgets.

  3. Determination of faults parameters controlling the Petroleum Systems Elements in the northern North Sea by using 3D basin Modelling

    Andriamihaja, Spariharijaona


    3D basin modelling of the northern North Sea region covering 4886km2 is performed in order to understand the petroleum system elements within the area. The approach used to obtain the most likely model is to analyze and determine quantitatively the faults properties controlling the hydrocarbons accumulations in the Gullfaks, Visund, Kvitebjørn, and Huldra fields. This approach is made by varying the faults properties defined by shale gauge ratio until the reserves in place in the four fields ...

  4. Growth Normal Faulting at the Western Edge of the Metropolitan Taipei Basin since the Last Glacial Maximum, Northern Taiwan

    Chih-Tung Chen; Jian-Cheng Lee; Yu-Chang Chan; and Chia-Yu Lu


    Growth strata analysis is an useful tool in understanding kinematics and the evolution of active faults as well as the close relationship between sedimentation and tectonics. Here we present the Shanchiao Fault as a case study which is an active normal fault responsible for the formation of the 700-m-thick late Quaternary deposits in Taipei Basin at the northern tip of the Taiwan mountain belt. We compiled a sedimentary record, particularly the depositional facies and their dated ages, at thr...

  5. Analysis of geological characteristics of uranium mineralization of Na Linggou in Husiliang located in the northern of Ordos basin

    In this paper, rock facies, the development of interlayer oxidation zone and the control factors and characteristics of uranium mineralization in northern Ordos basin in terms of beam areas call Adams Ridge sulcus satisfied lots Zhiluo uranium mineralization characteristics do lower concluded that the location uranium mineralization controlled by the interlayer oxidation zone of uranium deposits located in the developed parts of the faults. (author)

  6. Trace fossils associated to the end-Messinian unconformity in the northern border of the Bajo Segura Basin (SE Spain)

    Caracuel, Jesús Esteban; Corbí, Hugo; Estévez, Antonio; Giannetti, Alice; Monaco, Paolo; Pina, José Antonio; Soria, Jesús M.; Tent Manclús, José Enrique; Yébenes, Alfonso


    A detailed analysis of the Upper Messinian-Lower Pliocene at the northern border of the Bajo Segura Basin (BSB) has been carried out. Trace fossils of firm- and rockground were collected, aiding in the recognition of three ichnofacies: Glossifungites (types A and B), Entobia and Gnathichnus. The ichnological data provide evidence that the Pliocene flooding of the BSB, after the Messinian Salinity Crisis, was developed in two pulses. In the first one, the ingression penetrated only along the p...




    Full Text Available Since the Middle-Late Miocene, the Apennine chain was characterised by the development of several basins. These basins have been alternatively explained as extensional post-orogenic basins or syn-orogenic compressional basins. In this framework, the Pliocene depositional history of the Val d'Orcia Basin (Southern Tuscany is described, based on a sequence stratigraphic approach. Three depositional sequences (Vd3a-c have been recognized. The Vd3a sequence records marine ingression and subsequent relative sea-level highstand in a narrow W-E trending depression. Subsequent relative sea-level fluctuations led to a progressive basin widening and deposition of Vd3b and Vd3c sequences. Basin scale sedimentation was mainly controlled by relative sea-level changes, although accumulation of bioclastic deposits of the Vd3c sequence could have been influenced by climatic factors. Based on its wide bowl-shaped geometry, the Pliocene Val d'Orcia Basin has been interpreted as an inherited depression. This depression is thought to be originated by erosion at the Late Miocene-Early Pliocene transition. 

  8. Calculated Porosity of Volcanic Reservoir in Wangjiatun of the Northern Songliao Basin, NE China

    Xuanlong Shan; Chuanbiao Wa; Rihui Cheng; Wanzhu Liu


    In Wangjiatun area of the Northern Songliao Basin, reservoir space can be divided into three types: primary pore, secondary pore and fissure according to their origins,which can be subdivided into eight subtypes: macro-vesicule,shrank primary vesicule, alteration pore, groundmass corrosive pore, normal structural crack, corrosive structural crack,filled structural crack and groundmass shrank crack according to texture and origin of the pore space. It has characteristic of double pore medium. Volcanic porosities of small diameter samples (with diameter of ca. 2.5 cm) and large diameter samples (with diameter of ca. 21.5 cm) were tested in accordance with the characteristic of volcanic reservoir space. Volcanic porosities for small diameter samples correspond with matrix porosities and those of large diameter samples correspond with total porosities including matrix and fractured porosities. Models of the calculated porosity by acoustic wave or density of volcanic reservoir are established in view of those measured data. Comparison of calculated and measuredporosities shows that precision of calculated porosities is lower for rhyolite and tuffites, and higher for basaltand andesite.Relative errors of calculated porosities by model of large diameter samples are lower than those of small diameter samples, i. e. precision of the former is higher than that of the later.

  9. Cross-fault pressure depletion, Zechstein carbonate reservoir, Weser-Ems area, Northern German Gas Basin

    Corona, F.V.; Brauckmann, F.; Beckmann, H.; Gobi, A.; Grassmann, S.; Neble, J.; Roettgen, K. [ExxonMobil Production Deutschland GmbH (EMPG), Hannover (Germany)


    A cross-fault pressure depletion study in Upper Permian Zechstein Ca2 carbonate reservoir was undertaken in the Weser-Ems area of the Northern German Gas Basin. The primary objectives are to develop a practical workflow to define cross-fault pressures scenarios for Zechstein Ca2 reservoir drillwells, to determine the key factors of cross-fault pressure behavior in this platform carbonate reservoir, and to translate the observed cross-fault pressure depletion to fault transmissibility for reservoir simulation models. Analysis of Zechstein Ca2 cross-fault pressures indicates that most Zechstein-cutting faults appear to act as fluid-flow baffles with some local occurrences of fault seal. Moreover, there appears to be distinct cross-fault baffling or pressure depletion trends that may be related to the extent of the separating fault or fault system, degree of reservoir flow-path tortuosity, and quality of reservoir juxtaposition. Based on the above observations, a three-part workflow was developed consisting of (1) careful interpretation and mapping of faults and fault networks, (2) analysis of reservoir juxtaposition and reservoir juxtaposition quality, and (3) application of the observed cross-fault pressure depletion trends. This approach is field-analog based, is practical, and is being used currently to provide reliable and supportable pressure prediction scenarios for subsequent Zechstein fault-bounded drill-well opportunities.

  10. Biostratigraphy, sedimentology and paleoenvironments of the northern Danube Basin: Ratkovce 1 well case study

    Rybár Samuel


    Full Text Available The Ratkovce 1 well, drilled in the Blatné depocenter of the northern Danube Basin penetrated the Miocene sedimentary record with a total thickness of 2000 m. Biostratigraphically, the NN4, NN5 and NN6 Zones of calcareous nannoplankton were documented; CPN7 and CPN8 foraminifer Zones (N9, 10, 11 of the global foraminiferal zonation; and MMi4a; MMi5 and MMi6 of the Mediterranean foraminiferal zonation were recognized. Sedimentology was based on description of well core material, and together with SP and RT logs, used to characterize paleoenvironmental conditions of the deposition. Five sedimentary facies were reconstructed: (1 fan-delta to onshore environment which developed during the Lower Badenian; (2 followed by the Lower Badenian proximal slope gravity currents sediments; (3 distal slope turbidites were deposited in the Lower and Upper Badenian; (4 at the very end of the Upper Badenian and during the Sarmatian a coastal plain of normal marine to brackish environment developed; (5 sedimentation finished with the Pannonian-Pliocene shallow lacustrine to alluvial plain deposits. The provenance analysis records that the sediment of the well-cores was derived from crystalline basement granitoides and gneisses and from the Permian to Lower Cretaceous sedimentary cover and nappe units of the Western Carpathians and the Eastern Alps. Moreover, the Lower Badenian volcanism was an important source of sediments in the lower part of the sequence.

  11. Strategic groundwater resources in the Tagliamento River basin (northern Italy): hydrogeological investigation integrated with geophysical exploration

    Rapti-Caputo, Dimitra; Bratus, Antonio; Santarato, Giovanni


    The western sector of the Tagliamento River basin (Friuli Venezia-Giulia Region; northern Italy) is characterized by important water resources, both superficial and underground. In particular, in the Quaternary deposits of the plain, up to a depth of 500 m, six artesian aquifer systems exist. A large amount of lithological, geomorphological, and hydrogeological data is presented, allowing for definition of (a) the principal aquifer system of the area to a depth of about 500 m; (b) geometrical characteristics of the aquifers (thickness, lateral extension, etc); (c) the hydraulic parameters (hydraulic conductivity, transmissivity); (d) chemico-physical characteristics of the water; and (e) vulnerability to pollution of the aquifer systems. In a test area, where many boreholes were drilled for fresh water supply, the conceptual hydrogeological model was integrated by a detailed and repeated three-dimensional (3D) resistivity survey using combined electrical resistivity tomography (ERT) and time-domain electromagnetic (TDEM) soundings. ERT investigation was mainly used to get detailed information about geometry and porosity of the overburden and to calibrate the shallowest TDEM information.

  12. Digital resource modeling of the northern and central Appalachian Basin coal regions: Top producing coals

    Ruppert, L.; Tewalt, S.; Bragg, L.; Wallack, R.; Jenkins, J.; Tully, J. [Geological Survey, Reston, VA (United States)


    The US Geological Survey is currently conducting a coal resource assessment of the coal beds and zones that are expected to provide the bulk of the Nation`s coal resources for the next few decades. In partnership with the state geologic surveys of Kentucky, Tennessee, West Virginia, Virginia, Pennsylvania, Ohio, and Maryland, six coal beds will be digitally assessed in the northern and central Appalachian Basin coal region. In ascending stratigraphic order, the beds which range from the Lower Pennsylvanian Pocahontas Formation to the Upper Pennsylvanian Monongahela Group are the Pocahontas No. 3, Pond Creek, Fire Clay, Lower Kittanning, Upper Freeport, and Pittsburgh coals. Comprehensive stratigraphic and geochemical databases have been developed for the coal beds. Maps that show the extent and mined areas of the beds, structure contour, isopach, and overburden thickness have been compiled for the Pittsburgh coal bed and are in preparation for the other coal beds. The resource model for the Pittsburgh coal bed indicates that of the original 33.6 billion short tons (30.5 billion tonnes) of Pittsburgh coal, approximately 15.9 billion short tons (14.4 billion tonnes) remain. The remaining coal is, however, higher in ash and sulfur, and generally thinner and under thicker overburden cover.

  13. New palynological data from Karoo sediments, Mana Pools basin, northern Zimbabwe

    d'Engelbronner, E. R.


    The palynological associations of 16 Karoo samples, collected in the Mana Pools basin, Northern Zimbabwe, were studied, and four zonal assemblages can be recognized. Assemblage I (Kondo Pools Formation) is dominated by monosaccate pollen grains and diverse alete bisaccate pollen grains occur frequently. Important but rare marker genera include Limitisporites, Vittatina and Weylandites. These indicate a middle to late Early Permian age (e.g. Late Sakmarian to Early Artinskian). The palynological assemblage, derived from the Massive Sandstone Member, Angwa Sandstone Formation, is characterized by a small number of smooth and apiculate spores, but is lacking any age significant marker taxa. Assemblages II and III, both from the Alternations Member (Angwa Sandstone Formation), and Assemblage IV (Pebbly Arkose Formation) are dominated by alete bisaccate and multitaeniate pollen grains. The rare occurrence of Vittatina, Weylandites lucifer and Guttulapollenites hannonicus indicates a Late Permian to Early Triassic age for Assemblage II. Based on sedimentological data and literature, a preliminary age of Early Triassic (Induan) can be given. A range from latest Fassanian (Ladinian) to Lacian (Norian) for Assemblage III is indicated by the occurrence of Asseretospora gyrata, Cadargasporites senectus, Eucommiidites, Infernopollenites, Minutosaccus crenulatus, Retisulcites perforatus and Samaropollenites speciosus. Small amounts of Asseretospora gyrata, Cadargasporites senectus, Cycadopites, Microcachryidites and Minutosaccus crenulatus indicate a slightly larger age range for Assemblage IV (e.g. Carnien to Rhaetian).

  14. Geology and coal-bed methane resources of the northern San Juan Basin, Colorado and New Mexico

    This guidebook is the first of its kind: A focused look at coal-bed methane in a large Rocky Mountain Laramide basin. The papers in this volume cover every aspect of coal-bed methane in the San Juan Basin, including: The geology, environments of deposition, and geometry of the coal beds that contain the resource; the origin and migration history of the gas; basin-wide resource estimates; the engineering aspects of getting the gas out of the ground; the marketing and economics of producing coal-bed methane in the San Juan Basin; the legal ownership of the gas; state regulations governing well spacing and field rules; disposal of produced water; and land and mineral ownership patterns in the northern part of the basin. Also included are detailed papers on all of the major coal-bed methane fields in the basin, and in a paper on the history of Fruitland gas production, a discussion of most of the not-so-major fields. A small section of the book deals with geophysical methods, as yet still experimental, for surface detection of underground hydrocarbon resources. Individual papers have been processed separately for inclusion on the data base

  15. Precipitation thresholds for triggering floods in Corgo hydrographic basin (Northern Portugal)

    Santos, Monica; Fragoso, Marcelo


    The precipitation is a major cause of natural hazards and is therefore related to the flood events (Borga et al., 2011; Gaál et al., 2014; Wilhelmi & Morss, 2013). The severity of a precipitation event and their potential damage is dependent on the total amount of rain but also on the intensity and duration event (Gaál et al., 2014). In this work, it was established thresholds based on critical combinations: amount / duration of flood events with daily rainfall data for Corgo hydrographic basin, in northern Portugal. In Corgo basin are recorded 31 floods events between 1865 and 2011 (Santos et al., 2015; Zêzere et al., 2014). We determined the minimum, maximum and pre-warning thresholds that define the boundaries so that an event may occur. Additionally, we applied these thresholds to different flood events occurred in the past in the study basin. The results show that the ratio between the flood events and precipitation events that occur above the minimum threshold has relatively low probability of a flood happen. These results may be related to the reduced number of floods events (only those that caused damage reported by the media and produced some type of damage). The maximum threshold is not useful for floods forecasting, since the majority of true positives are below this limit. The retrospective analysis of the thresholds defined suggests that the minimum and pre warning thresholds are well adjusted. The application of rainfall thresholds contribute to minimize possible situations of pre-crisis or immediate crisis, reducing the consequences and the resources involved in emergency response of flood events. References Borga, M., Anagnostou, E. N., Blöschl, G., & Creutin, J. D. (2011). Flash flood forecasting, warning and risk management: the HYDRATE project. Environmental Science & Policy, 14(7), 834-844. doi: 10.1016/j.envsci.2011.05.017 Gaál, L., Molnar, P., & Szolgay, J. (2014). Selection of intense rainfall events based on intensity thresholds and

  16. The Post-Permian evolution of the Northern Part of the North German Basin

    Hansen, M. B.; Huebscher, C.; Lykke-Andersen, H.; Gajewski, D.; Dehghani, A.; Reicherter, K.


    In the frame of the Priority Program 1135 of the German Research Foundation (DFG) "Dynamics of sedimentary systems under varying stress conditions by example of the Central European Basin System", the scientific goal of the NeoBaltic project is to describe the post-Permian to recent geological evolution of the entire western Baltic Sea region, with a special emphasis on neotectonic activity and it relation to salt dynamics. The western Baltic Sea comprises the northern part of the North German Basin (NGB), a part of the Central European Basin System (CEBS), and the transitional zone between the NGB and the Baltic Shield. In order to investigate these scientific goals the Universities of Aarhus (Denmark) and Hamburg (Germany) has since 1998 completed seven marine campaigns in the western Baltic Sea, collecting 2D high resolution seismic (HRS), gravity and magnetic data in the entire region during different projects. Since 2003 all these data has been available for the NeoBaltic project. All together the data pool have more than 7000 km HRS, 5000 km gravity and 4000 km magnetic data. Until now the project work has been focused on the completion of the data processing and the digital interpretation of important Mesozoic and Cenozoic markers on the seismic sections from the Bays of Kiel and Mecklenburg. Furthermore, several maps have been completed from the potential field data (gravity and magnetic). As a result of the digital interpretation of the HRS data, the overall geological evolution of the northern part of the NGB can be subdivided into four distinct periods. During the Triassic and the Early Jurassic, E-W extension and the deposition of clastic sediments initiated the movement of the underlying Zechstein evaporites. This is seen by the presence of several salt pillows in the region. The deposition ceased during the Middle Jurassic, when the entire area was uplifted, due to the Mid North Sea Doming. The uplift resulted in a pronounced erosion of Upper Triassic

  17. Concerts of earthquakes and transverse dislocations in the Caucasus

    Pirouzian, S. A.


    The geologic-geophysical phenomenon of simultaneous fairly strong tremors or "concerts" of earthquakes in the territory of the Caucasus is considered. The tectonic interpretation of the phenomenon is proposed from the viewpoint of simultaneous activity of different parts of a seismogenic fault or the system of correlated disjunctive dislocations and especially, the transverse dislocations in the Caucasus.

  18. Depositional and provenance record of the Paleogene transition from foreland to hinterland basin evolution during Andean orogenesis, northern Middle Magdalena Valley Basin, Colombia

    Moreno, Christopher J.; Horton, Brian K.; Caballero, Victor; Mora, Andrés; Parra, Mauricio; Sierra, Jair


    The Central Cordillera and Eastern Cordillera of the northern Andes form the topographic flanks of the north-trending Magdalena Valley Basin. Constraining the growth of these ranges and intervening basin has implications for Andean shortening and the transformation from a foreland to hinterland basin configuration. We present sedimentological, paleocurrent, and sandstone petrographic results from Cenozoic type localities to provide insights into the tectonic history of the northern Middle Magdalena Valley Basin of Colombia. In the Nuevo Mundo Syncline, the mid-Paleocene transition from marine to nonmarine deposystems of the Lisama Formation corresponds with a paleocurrent shift from northward to eastward transport. These changes match detrital geochronological evidence for a contemporaneous shift from cratonic (Amazonian) to orogenic (Andean) provenance, suggesting initial shortening-related uplift of the Central Cordillera and foreland basin generation in the Magdalena Valley by mid-Paleocene time. Subsequent establishment of a meandering fluvial system is recorded in lower-middle Eocene strata of the lower La Paz Formation. Eastward paleocurrents in mid-Paleocene through uppermost Eocene fluvial deposits indicate a continuous influence of western sediment source areas. However, at the upper middle Eocene (˜40 Ma) boundary between the lower and upper La Paz Formation, sandstone compositions show a drastic decrease in lithic content, particularly lithic volcanic fragments. This change is accompanied by a facies shift from mixed channel and overbank facies to thick, amalgamated braided fluvial deposits of possible fluvial megafans, reflecting changes in both the composition and proximity of western sediment sources. We attribute these modifications to the growing influence of exhumed La Cira-Infantas paleohighs in the axial Magdalena Valley, features presently buried beneath upper Eocene-Quaternary basin fill along the western flank of the Nuevo Mundo Syncline. In

  19. The architecture of an incipient oceanic basin: a tentative reconstruction of the Jurassic Liguria-Piemonte basin along the Northern Apennines-Alpine Corsica transect

    Marroni, Michele; Pandolfi, Luca


    In this paper, a scenario for the early evolution of the Jurassic oceanic Liguria-Piemonte basin is sketched. For this purpose, four selected examples of ophiolite sequences from the Northern Apennines and Corsica are described and analyzed. In the External Ligurian units (Northern Apennines), the ocean-continent transition of the Adria plate was characterized by a basement made up of subcontinental mantle and lower continental crust, covered by extensional allochthons of upper crust. Both, the basement rocks and the extensional allochthons are cut by basaltic dikes and covered by basalts and pelagic deposits. The conjugate ocean-continent transition of the Corsica margin, represented by the Balagne nappe (Corsica), was composed of mantle peridotites and gabbros covered by basaltic flows and minor breccias, that in addition include continent-derived clasts. By contrast, the innermost (i.e., closest to the ocean) preserved area observed in the Internal Ligurian (Northern Apennines) and Inzecca (Corsica) units consists of former morphological highs of mantle peridotites and gabbros, bordered by small basins where the basement is covered by a volcano-sedimentary complex, characterized by ophiolitic breccias and cherts interlayered with basaltic flows. The overall picture resulting from our reconstructions suggests an asymmetric architecture for the Liguria-Piemonte basin with a central area bounded by two different transition zones toward the continental margins. This architecture can be interpreted as the result of a rifting process whose development includes a final stage characterized by passive, asymmetric extension of the lithosphere along an east-dipping detachment fault system.

  20. Palaeoclimatic oscillations in the Pliensbachian (Early Jurassic) of the Asturian Basin (Northern Spain)

    Gómez, Juan J.; Comas-Rengifo, María J.; Goy, Antonio


    One of the main controversial themes in palaeoclimatology involves elucidating whether climate during the Jurassic was warmer than the present day and if it was the same over Pangaea, with no major latitudinal gradients. There has been an abundance of evidence of oscillations in seawater temperature throughout the Jurassic. The Pliensbachian (Early Jurassic) constitutes a distinctive time interval for which several seawater temperature oscillations, including an exceptional cooling event, have been documented. To constrain the timing and magnitude of these climate changes, the Rodiles section of the Asturian Basin (Northern Spain), a well exposed succession of the uppermost Sinemurian, Pliensbachian and Lower Toarcian deposits, has been studied. A total of 562 beds were measured and sampled for ammonites, for biochronostratigraphical purposes, and for belemnites, to determine the palaeoclimatic evolution through stable isotope studies. Comparison of the recorded latest Sinemurian, Pliensbachian and Early Toarcian changes in seawater palaeotemperature with other European sections allows characterization of several climatic changes that are likely of a global extent. A warming interval partly coinciding with a δ13Cbel negative excursion was recorded at the Late Sinemurian. After a "normal" temperature interval, with temperatures close to average values of the Late Sinemurian-Early Toarcian period, a new warming interval containing a short-lived positive δ13Cbel peak, developed during the Early-Late Pliensbachian transition. The Late Pliensbachian represents an outstanding cooling interval containing a δ13Cbel positive excursion interrupted by a small negative δ13Cbel peak. Finally, the Early Toarcian represented an exceptional warming period, which has been pointed out as being responsible for the prominent Early Toarcian mass extinction.

  1. Long-term geochemical connections between the Samoan hotspot and the northern Lau and North Fiji Basins

    Price, A. A.; Jackson, M. G.; Blichert-Toft, J.; Hall, P. S.; Sinton, J. M.; Kurz, M. D.; Blusztajn, J.


    The Lau and North Fiji Basins provide a unique environment for the study of upper mantle flow around a subducting slab due to the juxtaposition of the Tonga Trench and the Samoan hotspot (Hart et al., 2004). Both geochemical and geophysical data suggest that material from the Samoan hotspot is leaking southward into the adjacent Lau Basin, but the direction and rate of mantle flow are difficult to constrain.Spatial variations in the isotope geochemistry of igneous rocks from the Lau Basin can provide a useful window on flow in the upper mantle. For example, some lavas from the Samoan hotspot exhibit high 3He/4He, and the observation of elevated 3He/4He at Rochambeau Bank in the nearby northern Lau Basin has been interpreted as the result of a 'finger-like' intrusion of Samoan-plume mantle into the region. However, high 3He/4He is rare even in Samoan lavas, so other geochemical signatures including radiogenic 87Sr/86Sr and Pb-isotopic compositions unique to the Samoan hotspot are useful for characterizing the spatial distribution of the Samoan component within the northern Lau and North Fiji Basins. We present analyses of a combination of geochemical tracers (He-Hf-Nd-Sr-Pb isotopes, major, and trace elements) measured on glasses from the northern Lau Basin and the North Fiji Basin. The samples have 3He/4He ratios that vary between 6 and 10.5 times atmospheric. The samples also show arange in isotopic values from extremely depleted (87Sr/86Sr=0.702892, 143Nd/144Nd=0.513218 and 176Hf/177Hf=0.283510 on a ridge 100km North of Fiji) to moderately enriched (87Sr/86Sr=0.703598, 143Nd/144Nd=0.512884 and 176Hf/177Hf=0.283082 in lavas fromPandora Ridge). Notably, moderately enriched isotopic compositions in Pandora Ridge lavas plot near Samoa's Upolu Island in isotope space, but are slightly shifted isotopically towards a depleted MORB mantle component. The new data suggestthat the western extent of the Samoan plume's influence in the region extends into both the

  2. A review of tectonics and sedimentation in a forearc setting: Hellenic Thrace Basin, North Aegean Sea and Northern Greece

    Maravelis, A. G.; Boutelier, D.; Catuneanu, O.; Seymour, K. St.; Zelilidis, A.


    Exposure of the forearc region of the North Aegean Sea, Greece, offers insight into evolving convergent margins. The sedimentary fill of the Thrace Basin during the Late Eocene to Oligocene time provides a record of subduction-driven processes, such as growth of magmatic arcs and construction of accretionary complexes. This large sediment repository received sediment from two sources. The southern (outboard) basin margin reflects the active influence of the exhumed accretionary prism (e.g. Pindic Cordillera or Biga peninsula), while the northern (inboard) margin records the effect of the magmatic arc in the Rhodope region. The forearc basin sedimentary fills shoal upward into shallow-marine strata but are dominated mainly by deep-marine facies. The depositional trend and stacking pattern are dominated by progradational patterns. This trend, which is observed in both basin margins, is related to tectonic deformation rather than sea-level fluctuations. Additional evidence for this tectonic uplift comes from the backstripping analysis. The accretionary complex provided material into the forearc basin. This material was transported northeast and formed a sand-rich turbidity system that evolved upslope into shallow-marine deposits. Stratigraphic data indicate that this turbidity system exhibits a successive landward (inboard) migration of the depocenter. Provenance data utilizing sandstone petrography, conglomerate clast composition, and bulk-rock geochemistry suggest that this system reflects an increased influx of mafic material into the basin. Volcanic arc-derived material was transported south and east and accumulated in deep-marine settings. Both stratigraphic and provenance data indicate a seaward (outboard) migration of the basin depocenter and a significant increase in felsic detritus into the forearc.

  3. Stress state variations among the clay and limestone formations of the molasse basin of Northern Switzerland

    Document available in extended abstract form only. Full text of publication follows: The design of geological repositories for radioactive waste responds to the requirements of technical feasibility and long-term safety in the context of a specific geological setting. An important aspect of the geological setting is the primary stress field. To a large extent the stress state controls repository induced effects such as the excavation damage zone and the associated potential changes in the waste isolation properties of the host rock. Therefore the measurement of the stress state receives some attention where the site selection for geological repositories focuses onto relatively weak host rocks such as clay-stones and marly shales that tend to develop a significant excavation damage zone. Measurements of the minimum stress magnitudes in a recently drilled geothermal well in the Molasse Basin of northern Switzerland have yielded a stress profile reaching from 592 m to 1455 m depth. It straddles several rock units and includes the top of the crystalline basement. The sedimentary sequence consists of Marine limestones, shales and marls unconformably covered by Tertiary rocks of the Molasse. In other parts of the basin the evaporitic rocks of the Triassic Muschelkalk formation at the base of the sedimentary layer served as a regional detachment and enabled thin skinned thrusting and the formation of the Jura Fold and Thrust Belt in the Late Miocene. The stress measurements have been performed in the open hole by Mini-frac tests. The method uses a double packer system to isolate a one meter long interval of the borehole that is then pressurized at high injection rates up to the breakdown of the formation. Repeated pressurization of the interval allows to determine the stress that acts on the newly created fracture. The total injected volume during such a test is in the range of a few litres and the size of the fracture that extends from the borehole normal to the minimum

  4. Thermal-rheological structure of lithosphere beneath the northern flank of Tarim Basin, western China:Implications for geodynamics

    LIU; Shaowen; WANG; Liangshu; LI; Cheng; LI; Hua; HAN; Yong


    Based on the data of geo-temperature and thermophysical parameters of rocks in the Kuqa Depression and the Tabei Uplift, northern flank of the Tarim Basin, in terms of the analytical solution of 1-D heat transfer equation, the thermal structure of the lithosphere under this region is determined. Our results show that the average surface heat flow of the northern flank of the Tarim Basin is 45 mW/m2, and the mantle heat flow is between 20 and 23 mW/m2; the temperature at crust-mantle boundary (Moho) ranges from 514℃ to 603℃ and the thermal lithosphere where the heat conduction dominates is 138-182 km thick. Furthermore, in combination with the P wave velocity structure resulting from the deep seismic sounding profile across this region and rheological modeling, we have studied the local composition of the lithosphere and its rheological profile, as well as the strength distribution. We find that the rheological stratification of the lithosphere in this region is apparent. The lowermost of the lower crust is ductile; however,the uppermost of the mantle and the upper and middle parts of the crust are both brittle layers,which is typically the so-called sandwich-like structure. Lithospheric strength is also characterized by the lateral variation, and the uplift region is stronger than the depression region. The lithospheric strength of the northem flank of the Tarim Basin decreases gradually from south to north; the Kuqa Depression has the lowest strength and the south of the Tabei Uplift is strongest.The total lithospheric strength of this region is 4.77× 1012-5.03 × 1013 N/m under extension, and 6.5 × 1012-9.4× 1013 N/m under compression. The lithospheric brittle-ductile transition depth is between 20 km and 33 km. In conclusion, the lithosphere of the northern flank of the Tarim Basin is relatively cold with higher strength, so it behaves rigidly and deforms as a whole, which is also supported by the seismic activity in this region. This rigidity of the




    Full Text Available The Upper Valdarno Basin, one of the most investigated Neogene–Quaternary basins of the Northern Apennines, developed during three main phases, as testified by the occurrence of three unconformity-bounded stratigraphic units (UBSUs in the basin infill. Despite numerous studies having been carried out, biochronological, paleoecological and stratigraphical issues in the lower portion of the Montevarchi Synthem (second phase have yet to be understood. Sandy deposits (Montecarlo Sand and Silt Unit, stratigraphically located in this portion of the Montevarchi Synthem, are the focus of this multidisciplinary study. These deposits conformably overlie sandy fluvio-eolian sediments and are, in turn, capped by fluvio-palustrine deposits through a progressive unconformity. Facies analysis suggest a sandy flood-basin environment for these deposits, characterised by variations in water discharge and flood event energy. Mollusc and fish remains, pointing to quiet or slow-moving shallow waters, have been affected by transport processes before final burial in overbank areas. Fish remains of the primary marine family Mugilids highlight a connection between the basin and the sea that was previously only supposed. Small mammal remains, referred to the rodent Mimomys polonicus, are coherent with a water-rich environment. Cyclic variations in shell content and sedimentological characteristics testify to the occurrence of short-term climatic oscillations during this warming phase. This study fits with paleomagnetic and radiometric datings and mammal biochronology, in indicating that the Montecarlo Sand and Silt Unit belongs to a time interval preceding the Reunion paleomagnetic event. The depositional evolution of the Montecarlo Unit was driven by climatic change from arid to humid conditions, related to a global increase in temperature that occurred between 2.4 and 2.2 Ma.

  6. Cheatgrass percent cover change: Comparing recent estimates to climate change − Driven predictions in the Northern Great Basin

    Boyte, Stephen P.; Wylie, Bruce K.; Major, Donald J.


    Cheatgrass (Bromus tectorum L.) is a highly invasive species in the Northern Great Basin that helps decrease fire return intervals. Fire fragments the shrub steppe and reduces its capacity to provide forage for livestock and wildlife and habitat critical to sagebrush obligates. Of particular interest is the greater sage grouse (Centrocercus urophasianus), an obligate whose populations have declined so severely due, in part, to increases in cheatgrass and fires that it was considered for inclusion as an endangered species. Remote sensing technologies and satellite archives help scientists monitor terrestrial vegetation globally, including cheatgrass in the Northern Great Basin. Along with geospatial analysis and advanced spatial modeling, these data and technologies can identify areas susceptible to increased cheatgrass cover and compare these with greater sage grouse priority areas for conservation (PAC). Future climate models forecast a warmer and wetter climate for the Northern Great Basin, which likely will force changing cheatgrass dynamics. Therefore, we examine potential climate-caused changes to cheatgrass. Our results indicate that future cheatgrass percent cover will remain stable over more than 80% of the study area when compared with recent estimates, and higher overall cheatgrass cover will occur with slightly more spatial variability. The land area projected to increase or decrease in cheatgrass cover equals 18% and 1%, respectively, making an increase in fire disturbances in greater sage grouse habitat likely. Relative susceptibility measures, created by integrating cheatgrass percent cover and temporal standard deviation datasets, show that potential increases in future cheatgrass cover match future projections. This discovery indicates that some greater sage grouse PACs for conservation could be at heightened risk of fire disturbance. Multiple factors will affect future cheatgrass cover including changes in precipitation timing and totals and

  7. Past, present and future formation of groundwater resources in northern part of Baltic Artesian Basin

    Marandi, A.; Vallner, L.; Vaikmae, R.; Raidla, V.


    Cambrian-Vendian Aquifer System (CVAS) is the deepest confined aquifer system used for water consumption in northern part of Baltic Artesian Basin (BAB). A regional groundwater flow and transport model (Visual Modflow) was used to investigate the paleohydrogeological scientific and contemporary management problems of CVAS. The model covers the territory of Estonia and its close surrounding, all together 88,000 km2 and includes all main aquifers and aquitards from ground surface to as low as the impermeable part of the crystalline basement. Three-dimensional distribution of groundwater heads, flow directions, velocities, and rates as well as transport and budget characteristics were simulated by the model. Water composition was changed significantly during the last glaciations.Strongly depleted O and H stable isotope composition, absence of 3H and low radiocarbon concentration are the main indicators of glacial origin of groundwater in the Cambrian-Vendian aquifer in northern Estonia. The noble gas analyses allowed concluding, that palaeorecharge took place at temperatures around the freezing point. While in North Estonia, most of water was changed by glacial melt water, high salinity water is till preserved in Southern part of Estonia.First results of modeling suggest that during the intrusion period lasting 7.3-9.3 ka the front of glacial thaw water movement had southeast direction and reachedto 180-220 kmfrom CVAS outcrop in Baltic Sea. Confining layer of CVAS is cut through by deep buried valleys in several places in North Estonia making possible for modern precipitation to infiltrate into aquifer system in present day. In case of natural conditions, the water pressure of CVAS is few meters above sea level and most of valleys act as discharge areas for aquifers system. Two regional depression ones have formed in North Estonia as a result of groundwater use from CVAS. Water consumption changes the natural groundwater gradient, flow direction and thereforerecharge

  8. Review of the Upper Jurassic-Lower Cretaceous stratigraphy in Western Cameros basin, Northern Spain

    Vidal, Maria del Pilar Clemente


    The Upper Jurassic-Lower Cretaceous stratigraphy of the Cameros basin has been reviewed. In Western Cameros the stratigraphic sections are condensed but they have a parallel development with the basin depocentre and the same groups have been identified. The Tera Group consists of two formations...

  9. Structure of the Wagner Basin in the Northern Gulf of California From Interpretation of Seismic Reflexion Data

    Gonzalez, M.; Aguilar, C.; Martin, A.


    The northern Gulf of California straddles the transition in the style of deformation along the Pacific-North America plate boundary, from distributed deformation in the Upper Delfin and Wagner basins to localized dextral shear along the Cerro Prieto transform fault. Processing and interpretation of industry seismic data adquired by Petroleos Mexicanos (PEMEX) allow us to map the main fault structures and depocenters in the Wagner basin and to unravel the way strain is transferred northward into the Cerro Prieto fault system. Seismic data records from 0.5 to 5 TWTT. Data stacking and time-migration were performed using semblance coefficient method. Subsidence in the Wagner basin is controlled by two large N-S trending sub-parallel faults that intersect the NNW-trending Cerro Prieto transform fault. The Wagner fault bounds the eastern margin of the basin for more than 75 km. This fault dips ~50° to the west (up to 2 seconds) with distinctive reflectors displaced more than 1 km across the fault zone. The strata define a fanning pattern towards the Wagner fault. Northward the Wagner fault intersects the Cerro Prieto fault at 130° on map view and one depocenter of the Wagner basin bends to the NW adjacent to the Cerro Prieto fault zone. The eastern boundary of the modern depocenter is the Consag fault, which extends over 100 km in a N-S direction with an average dip of ~50° (up to 2s) to the east. The northern segment of the Consag fault bends 25° and intersects the Cerro Prieto fault zone at an angle of 110° on map view. The acoustic basement was not imaged in the northwest, but the stratigraphic succession increases its thickness towards the depocenter of the Wagner basin. Another important structure is El Chinero fault, which runs parallel to the Consag fault along 60 km and possibly intersects the Cerro Prieto fault to the north beneath the delta of the Colorado River. El Chinero fault dips at low-angle (~30°) to the east and has a vertical offset of about 0

  10. Evolution of the Neogene Andean foreland basins of the Southern Pampas and Northern Patagonia (34°-41°S), Argentina

    Folguera, Alicia; Zárate, Marcelo; Tedesco, Ana; Dávila, Federico; Ramos, Victor A.


    The Pampas plain (30°-41°S) has historically been considered as a sector that evolved independently from the adjacent Andean ranges. Nevertheless, the study of the Pampas showed that it is reasonable to expect an important influence from the Andes into the extraandean area. The Pampas plain can be divided into two sectors: the northern portion, adjacent to the Pampean Ranges, has been studied by Davila (2005, 2007, 2010). The southern sector (34°-41°S) is the objective of the present work. The study of this area allowed to characterize two separate foreland basins: the Southern Pampa basin and the Northern Patagonian basin. The infill is composed of Late Miocene and Pliocene units, interpreted as distal synorogenic sequences associated with the late Cenozoic Andean uplift at this latitudinal range. These foreland basins have been defined based on facies changes, distinct depositional styles, along with the analysis of sedimentary and isopach maps. The basins geometries are proposed following De Celles and Gilles (1996) taking into account the infill geometry, distribution and grain size. In both cases, these depocenters are located remarkably far away from the Andean tectonics loads. Therefore they cannot be explained with short-wave subsidence patterns. Elastic models explain the tectonic subsidence in the proximal depocenters but fail to replicate the complete distal basins. These characteristics show that dynamic subsidence is controlling the subsidence in the Southern Pampas and Northern Patagonian basins.

  11. Hydrogeochemistry and stable isotopes of ground and surface waters from two adjacent closed basins, Atacama Desert, northern Chile

    Alpers, C.N.; Whittemore, D.O.


    The geochemistry and stable isotopes of groundwaters, surface waters, and precipitation indicate different sources of some dissolved constituents, but a common source of recharge and other constituents in two adjacent closed basins in the Atacama Desert region of northern Chile (24??15???-24??45???S). Waters from artesian wells, trenches, and ephemeral streams in the Punta Negra Basin are characterized by concentrations of Na>Ca>Mg and Cl ???SO4, with TDS Mg ??? Ca and SO4 > Cl, with TDS also Mg ??? Ca and SO4 > Cl, but with TDS up to 40 g/l. The deep mine waters have pH between 3.2 and 3.9, and are high in dissolved CO2 (??13 C = -4.8%PDB), indicating probable interaction with oxidizing sulfides. The deep mine waters have ??18O values of ???-1.8%.compared with values < -3.5??? for other Hamburgo Basin waters; thus the mine waters may represent a mixture of meteoric waters with deeper "metamorphic" waters, which had interacted with rocks and exchanged oxygen isotopes at elevated temperatures. Alternatively, the deep mine waters may represent fossil meteoric waters which evolved isotopically along an evaporative trend starting from values quite depleted in ??18O and ??Dd relative to either precipitation or shallow groundwaters. High I/Br ratios in the Hamburgo Basin waters and La Escondida mine waters are consistent with regionally high I in surficial deposits in the Atacama Desert region and may represent dissolution of a wind-blown evaporite component. Rain and snow collected during June 1984, indicate systematic ??18O and ??D fractionation with increasing elevation between 3150 and 4180 m a.s.l. (-0.21??.??18O and -1.7??.??D per 100 m). Excluding the deep mine waters from La Escondida, the waters from the Hamburgo and Punta Negra Basins have similar ??D and ??18O values and together show a distinct evaporative trend (??D = 5.0 ??18O - 20.2). Snowmelt from the central Andes Cordillera to the east is the most likely source of recharge to both basins. Some of the

  12. Hydrological application of the INCA model with varying spatial resolution and nitrogen dynamics in a northern river basin

    K. Rankinen


    Full Text Available As a first step in applying the Integrated Nitrogen model for CAtchments (INCA to the Simojoki river basin (3160 km2, this paper focuses on calibration of the hydrological part of the model and nitrogen (N dynamics in the river during the 1980s and 1990s. The model application utilised the GIS land-use and forest classification of Finland together with a recent forest inventory based on remote sensing. In the INCA model, the Hydrologically Effective Rainfall (HER is used to drive the water flow and N fluxes through the catchment system. HER was derived from the Watershed Simulation and Forecast System (WSFS. The basic component of the WSFS is a conceptual hydrological model which simulates runoff using precipitation, potential evapotranspiration and temperature data as inputs. Spatially uniform, lumped input data were calculated for the whole river basin and spatially semi-distributed input data were calculated for each of the nine sub-basins. When comparing discharges simulated by the INCA model with observed values, a better fit was obtained with the semi-distributed data than with the spatially uniform data (R2 0.78 v. 0.70 at Hosionkoski and 0.88 v. 0.78 at the river outlet. The timing of flow peaks was simulated rather well with both approaches, although the semi-distributed input data gave a more realistic simulation of low flow periods and the magnitude of spring flow peaks. The river basin has a relatively closed N cycle with low input and output fluxes of inorganic N. During 1982-2000, the average total N flux to the sea was 715 tonnes yr–1, of which 6% was NH4-N, 14% NO3-N, and 80% organic N. Annual variation in river flow and the concentrations of major N fractions in river water, and factors affecting this variation are discussed. Keywords: northern river basin, nitrogen, forest management, hydrology, dynamic modelling, semi-distributed modelling

  13. Paleoenvironmental and source rock assessment of black shales of Pennsylvanian Age, Powder River and northern Denver basins

    Clayton, J.L.; King, J.D.; Lubeck, C.M.; Leventhal, J.S.; Daws, T.A.


    Thin Middle Pennsylvanian (Desmoinesian) organic-rich black shales (cumulative thickness < 50 ft) underlie much of the northern Denver basin and southeastern Powder River basin. In the Powder River basin, these shales are part of the middle member of the Minnelusa Formation. During Desmoinesian time, the present area of the southeastern Powder River basin and Nebraska was a shallow, at times highly saline, restricted sea. In contrast, in the present area of northeastern Colorado, black shales were deposited in a marine environment with normal salinity that was probably continuous with the Mid-Continent Pennsylvanian sea. Assessment of the paleoenvironment has been carried out using organic geochemical parameters. Shales deposited in the restricted basin setting contain abundant porphyrins (25,000-30,000 ppm relative to total extractable organic matter) and significant quantities of aryl isoprenoids. The aryl isoprenoid compounds (1) are evidence for the presence of the sulfur bacteria families Chlorobiaceae and possibly Chromatiaceae and (2) indicate that euxinic conditions existed in the water column. High ratios of sulfur to carbon in the shales support this interpretation. In contrast, extracts from black shale in the normal sea to the south contain lower porphyrin concentrations (generally less than 1000 ppm) and aryl isoprenoids are minor constituents or are absent. Sulfur/carbon ratios in these latter shales are similar to those observed for normal marine shales (that is, not euxinic conditions). Other paleoenvironmental indicators (sterane composition, alkane distribution) are consistent with these observations. Bulk organic matter in the black shales from both environments is type II and has good source potential for generation of liquid hydrocarbons during catagenesis. Pyrolysis yields of 50 kg/MT (50,000 ppm) are common, and in some shales, yield is 100 kg/MT (100,000 ppm).


    Yakobishvili-piralishvili, Lela


    The geocultural orientation of the Caucasus, and Georgia as its part, is growing more and more important in the age of globalization. This process has already offered Caucasian geoculture new possibilities; the Caucasus has been given the chance of becoming the only cultural transit region where many different cultures meet. Cultural diffusion will not be its only function: it stands a good chance of becoming a topos of the dialogue of cultures. As part of the topos of the Georgian geoculture...


    Hanahu, Ruslan


    Globalization is undoubtedly a complex and contradictory sociocultural phenomenon affecting both numerically large and small nationalities, but its consequences can differ. The cultures of numerically small ethnic groups experience the consequences of globalization under the same conditions as large nationalities. But whereas large ethnic groups are in relatively little danger of losing their language and culture, the threat to the culture and uniqueness of numerically small Caucasian nationa...

  16. Gas hydrate formation and accumulation potential in the Qiangtang Basin, northern Tibet, China

    Highlights: • Qiangtang Basin is the biggest residual petroleum-bearing basin in Tibet Plateau. • The Late Triassic Tumen Gela Formation is the most important gas source rock. • Seventy-one potential anticline structural traps have been found. • A favorable geothermal condition for gas hydrate formation. • A large number of mud volcanoes were discovered in the basin. - Abstract: The Qiangtang Basin is the biggest residual petroleum-bearing basin in the Qinghai–Tibet Plateau, and is also an area of continuous permafrost in southwest China with strong similarities to other known gas-hydrate-bearing regions. Permafrost thickness is typically 60–180 m; average surface temperature ranges from −0.2 to −4.0 °C, and the geothermal gradient is about 2.64 °C/100 m. In the basin, the Late Triassic Tumen Gela Formation is the most important gas source rock for gas, and there are 34.3 × 108 t of gas resources in the Tumen Gela Formation hydrocarbon system. Seventy-one potential anticline structural traps have been found nowadays covering an area of more than 30 km2 for each individual one, five of them are connected with the gas source by faults. Recently, a large number of mud volcanoes were discovered in the central Qiangtang Basin, which could be indicative of the formation of potential gas hydrate. The North Qiangtang depression should be delineated as the main targets for the purpose of gas hydrate exploration

  17. Radioecological monitoring of south Caucasus - main results

    Basing in surrounding ambience at present radioactive on its origin possible to split into two main groups: artificial and natural radioactive. How is obvious from the most names, natural based in the nature nearly with first days of its shaping and are its by the component. Artificial - not existed or not saved in the nature - having radioactive characteristics isotopes 'appeared' as a result artificial doing atoms. Getting into surrounding ambience as a result person activity artificial (systematically or episodic detectable there) possible conditionally split into three subgroups. Artificial radioactive isotopes, got into surrounding natural ambience as a result anthropogenic activity, in principal (ecological) are distinguished from the natural radioactive isotopes by fetters and particularities to migration on ecological chains, but, consequently, and nature 'influence'. Sufficiently remind that if in biosphere practically no ecological niches, in which goes an accumulation natural, capable to give significant dozing effect; for the artificial (isotopes of iodine, isotopes a strontium, caesium) exactly ability be accumulated in separate 'niches' ecological chain or in separate organs or weaving an organism (thyroid gland for the iodine) do artificial radioisotopes hygienic extremely dangerous. Location of Caucasus in the area of approximate location of firing ranges of test, (after the series 1961-1962 conducted by USSR in the North hemisphere this were test China) and damages on Chernobyl, in the area of most intensity stratosphere - troposphere exchange, manifests themselves: 1. Early approach spring-year maximum; 2. More clear maximum in the seasonal move; 3. The Greater fallout levels in contrast with other regions of country; 4. The Greater 'sensitivity' to 'fresh' products. Structure of global fallout on the under investigation region is stipulated: 1. Decreasing the fallout levels from the north on the south. 2. Vertical fallout levels (growth with the

  18. The Eurasian Otter in the South Caucasus

    Gorgadze G.


    Full Text Available Seven species of Mustelidae are to be found in the south Caucasus (Armenia, Azerbaijan and Georgia: Lutra lutra, Martes martes, Martes foina, Meles meles, Mustela vison, Mustela nivalis and Vormela peregusna. The rarest of these species are the Eurasian otter (Lutra lutra and the marbled polecat (Vormela peregusna. The Eurasian otter, one of most endangered species of the south caucasian fauna, is still suffering under the influence of poaching, habitat loss, disturbance and pollution. No fundamental research has been undertaken on otters in any of the south Caucasian countries and, therefore, data provided in the literature are scarce. Further, no DNA analysis has been undertaken in this part of the world and, therefore, the actual number of subspecies is not clear.

  19. Seismo-stratigraphic evolution of the northern Austral Basin and its possible relation to the Andean tectonics, onshore Argentina.

    Sachse, Victoria; Anka, Zahie; Pagan, Facundo; Kohler, Guillermina; Cagnolatti, Marcelo; di Primio, Rolando; Rodriguez, Jorge


    The Austral Basin is situated in a formerly and recently high active tectonic zone in southern Argentina. The opening of the South Atlantic to the east, the opening of the Drake Passage in the south, and the subduction related to the rise of the Andes to the west, had major influence on the study area. To identify the impact of the tectonic events on basin geometry, sediment thickness and depocenter migration through time, 2D seismic interpretation was performed for an area of approx. 180.000 km² covering the onshore northern Austral Basin. A total of 10 seismic horizons were mapped and tied to the stratigraphy from well reports, representing 9 syn- and post- rift sequences. The main units are: Basement (U1), Jurassic Tobifera Formation (U2), Early Cretaceous (U3), Late Cretaceous (U4), sub-unit Campanian (U4A), Paleocene (U5), Eocene (U6), Oligocene (U7), Miocene (U8), and Plio-Pleistocene (U9). Main tectonic events are identified representing the break-up phase forming graben systems and the evolution from the ancient backarc Rocas Verdes Basin to the foreland Austral Basin. Inversion and changes in the tectonic regime are concomitant with onlapping and thinning of the base of the Upper Cretaceous to Campanian sediments, while the Top of the Upper Cretaceous represents a Maastrichtian unconformity. Units depth maps show a triangular geometry since the Jurassic, tracing the north-eastern basement high and deepening to the south. Since the Campanian the former geometry of basin fill changed and deepening to the south stopped. Beginning of the foreland phase is assigned to this time as well as changes in the stress regime. Paleogene times are marked by a relatively high sedimentation rate coupled with enduring thermal subsidence, on-going rise of the Andes and changes in the convergence rates of the Nazca relative to the South American plate. Onset of sediment supply from the Andes (Incaic phase) resulted in enhanced sedimentation rates during the Paleocene

  20. Raft tectonics in northern Campos Basin; Tectonica de jangada (raft tectonics) na area norte da Bacia de Campos

    Castro, Marilia R. de [Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacases, RJ (Brazil)]|[PETROBRAS, Macae, RJ (Brazil). Unidade de Negocio da Bacia de Campos; Fugita, Adhemar M. [Universidade do Estado, Rio de Janeiro, RJ (Brazil). Programa de Recursos Humanos da ANP


    In the northern area of Campos Basin salt gliding/spreading processes promoted the break-up and transport of Cretaceous and Tertiary rocks overlying the evaporites. This process is known as raft tectonics, and it represents the most extreme form of thin-skinned extension above the salt decollement surface. Three distinct geotectonic domains were recognized that formed in response to the raft tectonics. The first one, confined to the shallower shelf portion of the basin, is characterized by minor extension (pre-raft domain), probably because of small salt thickness and low gradient. In the second domain (or disorganized rafts domain), located in distal platformal and slope areas, seismic sections show the occurrence of blocks or rafts with angular shapes, sometimes imbricated and frequently discontinuous. In the third domain, or domain of organized rafts, located in bacinal region, seismic sections show a more continuous raft pattern, often folded because of salt compression in the distal portions of the basin. The main purposes of this work is to characterize these three tectonic domains distinguished by raft tectonics, as well as their importance in hydrocarbon accumulations in calcarenites. (author)

  1. Geologic implications of large-scale trends in well-log response, northern Green River Basin, Wyoming

    Well-log response in lower Tertiary and Upper Cretaceous rocks in the northern Green River basin, Wyoming, is examined. Digitally recorded well-log data for selected wells located throughout the basin were processed by computer and displayed as highly compressed depth-scale plots for examining large-scale geologic trends. Stratigraphic units, formed under similar depositional conditions, are distinguishable by differing patterns on these plots. In particular, a strong lithologic contrast between Tertiary and underlying Upper Cretaceous non-marine clastic rocks is revealed and correlated through the study area. Laboratory analysis combined with gamma-ray spectrometry log data show that potassium feldspars in the arkosic Tertiary sandstones cause the contrast. The nature and extent of overpressuring has been examined. Data shift on shale conductivity and shale acoustic transit-time plots, previously ascribed to changes in pore pressure, correspond to stratigraphic changes and not necessarily with changes in pore pressure as indicated by drilling-mud weights. Gulf Coast well-log techniques for detecting overpressuring are unreliable and ineffectual in this basin, which has experienced significantly different geologic depositional and tectonic conditions

  2. The linkage between longitudinal sediment routing systems and basin types in the northern South China Sea in perspective of source-to-sink

    Su, Ming; Hsiung, Kan-Hsi; Zhang, Cuimei; Xie, Xinong; Yu, Ho-Shing; Wang, Zhenfeng


    Using bathymetric and seismic data, this study describes the morpho-sedimentary features in Qiongdongnan basin and southwest Taiwan collision basin, northern South China Sea and reveals the linkages between sediment routing system and basin types. The modern Central Canyon in the Qiongdongnan basin is located along the rift margin, and subparallel to the shelf-break southeast of Hainan Island. The modern Central Canyon develops along the basin axis (i.e., Xisha Trough) and longitudinally transports sediments eastward which are mainly supplied by northern continental slope. The Penghu Canyon in the southwest Taiwan collision basin is located along the collision boundary parallel to the strike of the adjacent uplifted Taiwan orogen. The Penghu Canyon develops along the tilting basin axis transporting sediments longitudinally southward to the deep-sea basin and Manila Trench. The Penghu Canyon is supplied with sediments from both flank Kaoping and South China Sea slopes where tributary canyons and channels transport sediments down-slope and feed the axial canyon. The certain basin types may be occupied by particular styles of sediment routing system. By comparing the morpho-sedimentary features and basin characteristics associated with the modern Central Canyon to that of the Valencia Channel in NW Mediterranean Sea, the longitudinal sediment routing system in rift basin type can be determined. In contrast, the longitudinal sediment routing systems in collision setting can be represented by the comparable examples of Penghu Canyon in southwest Taiwan collision basin and Markham Canyon in western Solomon Sea. The rift type sediment routing system is characterized by an axial canyon with a single sediment supply from land drainage margin. In contrast, sediment routing system in collision type basins consists of an axial canyon and dual sediment supplies from flank adjacent slopes. The axial canyons in collision basins are more active than that of the rift basin due to

  3. Neotectonic aspects of the northern margin of the Adana–Cilicia submarine basin, NE Mediterranean

    E Ozel; A Ulug; B Pekcetinoz


    The sedimentary basins that dominate the north-eastern Mediterranean (Adana–Cilicia basins in the west and Iskenderun basin in the east) are located on the flanks of a partly submerged positive structure (a part of the Africa–Eurasia convergence zone) along which strike-slip faults are evident. This study summarizes the findings of two seismic surveys carried out in the Alanya– Mersin offshore region. Some 850 km of geophysical survey lines were compiled on these cruises. Based on the results determined from these surveys, the north and central part of Adana–Cilicia basin can be subdivided into eastern, central and western structural sub-basins separated by the Ecemiş fault complex in the east and the Anamur–Kormakiti structural high in the west at the same time. Results of this study also indicate that Ecemiş and Anamur–Kormakiti faults are active. Late Miocene regional compression was responsible for the compartmentation of this complex into the present arrangement and has initiated the rotational regime which has governed subsequent tectonic developments, notably the extensional behaviour of the NE–SW trending Ecemiş and Anamur–Kormakiti faults and the transpressive behaviour of the NNE–SSW trending border fault complex.

  4. Paleogeographic significance of Upper Triassic basinal succession of the Tamar Valley, northern Julian Alps (Slovenia

    Gale Luka


    Full Text Available The Julian Alps (western Slovenia structurally belong to the eastern Southern Alps. The Upper Triassic succession mostly consists of shallow water platform carbonates of the Dolomia Principale-Dachstein Limestone system and a deep water succession of the Slovenian Basin outcropping in the southern foothills of the Julian Alps. In addition to the Slovenian Basin, a few other intraplatform basins were present, but they remain poorly researched and virtually ignored in the existing paleogeographic reconstructions of the eastern Southern Alps. Herein, we describe a deepening-upward succession from the Tamar Valley (north-western Slovenia, belonging to the Upper Triassic Tarvisio Basin. The lower, Julian-Tuvalian part of the section comprises peritidal to shallow subtidal carbonates (Conzen Dolomite and Portella Dolomite, and an intermediate carbonate-siliciclastic unit, reflecting increased terrigenous input and storm-influenced deposition (Julian-lowermost Tuvalian shallow-water marlstone and marly limestone of the Tor Formation. Above the drowning unconformity at the top of the Portella Dolomite, Tuvalian well-bedded dolomite with claystone intercalations follows (Carnitza Formation. The latter gradually passes into the uppermost Tuvalian–lowermost Rhaetian bedded dolomite with chert and slump breccias, deposited on a slope and/or at the toe-of-slope (Bača Dolomite. Finally, basinal thin-bedded bituminous limestone and marlstone of Rhaetian age follow (Frauenkogel Formation. The upper part of the Frauenkogel Formation contains meter-scale platform-derived limestone blocks, which are signs of platform progradation. The Tarvisio Basin may have extended as far as the present Santo Stefano di Cadore area, representing a notable paleogeographic unit at the western Neotethys margin.

  5. Hydrochemistry (major and trace elements of Lake Malawi (Nyasa, Tanzanian Northern Basin: local versus global considerations

    P. Branchu


    Full Text Available This paper presents the first inventory of dissolved minor and trace element (F, Al, Fe, Mn, Ba, Cd, Cr, Cu, Pb, Mo, Bi, Sr, Zn concentrations in Lake Malawi, the second largest African lake. Sampling was carried out during 1993 dry season in the northern part of the lake. Trace metal concentrations were measured, together with Ca, Mg, Na, K, Cl, SO4, Alkalinity and Si, along three profiles in the lake northern extremity, in five tributaries and two on-land hydrothermal springs. Water profiles show similar elemental distributions and concentrations that are influenced by lake physical-chemical stratification. Stratification, assessed using temperature, conductivity, Si and Mn profiles, is characterised by two boundaries: the thermocline (70–90 m and the oxicline (150–190 m. Elemental water concentrations are discussed using simple covariance analyse. Epilimnetic concentrations and distribution are also influenced by atmospheric deposition and river diving. Comparison of dissolved concentrations for potentially polluting elements with World Health Organisation Guidelines and those reported for other East African lakes shows that this reservoir is uncontaminated despite an increasing human stress. Major element behaviour is assessed through a 3 boxes model. In this model Cl and K are conservative elements whereas Si is removed from the solution by diatom productivity and sedimentation. Ca, Na, Mg and alkalinity show low reactivity. Evaporation is one of the controlling factors of lake element concentration that superimposes on the watershed control. Hydrothermal activity, not evidenced in the lake, controls the chemistry of one of the main northern tributary. Chemical comparison between Northern rivers and other tributaries characterises the geographical and geological specificity of studied northern watershed. Moreover the lake annual chemical budget shows that northern watershed generates the main elemental input to the lake


    Mellors, R; Gok, R; Sandvol, E


    The southwest edge of Eurasia is a tectonically and structurally complex region that includes the Caspian and Black Sea basins, the Caucasus Mountains, and the high plateaus south of the Caucasus. Crustal and upper mantle velocities show great heterogeneity in this region and regional phases display variations in both amplitudes and travel time. Furthermore, due to a lack of quality data, the region has largely been unexplored in terms of the detailed lithospheric seismic structure. A unified high-resolution 3D velocity and attenuation model of the crust and upper mantle will be developed and calibrated. This model will use new data from 23 new broadband stations in the region analyzed with a comprehensive set of techniques. Velocity models of the crust and upper mantle will be developed using a joint inversion of receiver functions and surface waves. The surface wave modeling will use both event-based methods and ambient noise tomography. Regional phase (Pg, Pn, Sn, and Lg) Q model(s) will be constructed using the new data in combination with existing data sets. The results of the analysis (both attenuation and velocity modeling) will be validated using modeling of regional phases, calibration with selected events, and comparison with previous work. Preliminary analyses of receiver functions show considerable variability across the region. All results will be integrated into the KnowledgeBase.

  7. National Account Energy Alliance Final Report for the Basin Electric Project at Northern Border Pipeline Company's Compressor Station #7, North Dakota

    Sweetzer, Richard [Exergy Partners Corp.; Leslie, Neil [Gas Technology Institute


    A field research test and verification project was conducted at the recovered energy generation plant at Northern Border Pipeline Company Compressor Station #7 (CS#7) near St. Anthony. Recovered energy generation plant equipment was supplied and installed by ORMAT Technologies, Inc. Basin Electric is purchasing the electricity under a purchase power agreement with an ORMAT subsidiary, which owns and operates the plant.

  8. Recent area and volume changes of Marukh glacier in western Caucasus

    Kutuzov, S.; Lavrentiev, I. I.; Petrakov, D. A.; Macheret, Yu. Ya.


    Field studies have been carried out at Marukh glacier located in western part of the Northern Caucasus in summer 2011. Studies included ground-based radio-echo sounding measurements at a frequency of 20 MHz and glacier surface elevation survey using a dual frequency differential GPS receiver. Marukh Glacier is most western valley type glacier in the Russian Greater Caucasus. It is located 60 km from the Black Sea and was selected as most maritime glacier in the Soviet Union for direct measurements of ice, water and energy balances during IHD (International Hydrologycal Decade) in 1966-67-1981-82 when mass balance measurements were accompanied by meteorological observations and several topographic map were completed in scale of 1:10000. Detailed volume and surface area changes of the glacier for the period 1945-2011 were obtained using aerial photo, satellite images and topographic maps analysis. Annual glacier accumulation, ablation and mass balance have been estimated for the period of 1967 to 2011 using direct measurements (1967-1982) and mass balance reconstruction based on meteorological data. It is founded that Marukh glacier is retreating and has reduced its surface area by 17% over the past 66 years. Glacier volume is 0,276 km3 in 2011 and has decreased by 0,06 km3 since 1967.

  9. The northern and central Appalachian basin coal region -- The Upper Freeport and Pond Creek coal bed assessments

    Ruppert, L.; Tewalt, S.; Bragg, L.; Wallack, R.; Freeman, P.; Tully, J.


    The Upper Freeport and Pond Creek coal beds are two of six coal beds being assessed by the US Geological Survey (USGS) in the northern and central Appalachian basin coal region. The coal resource assessments were designed to provide up-to-date, concise data on the location, quantity, and quality of US coals for Federal agencies, the public, industry and academia. Assessment products are fully digital and include original and remaining resource estimates; maps depicting areal extent, mined areas, geologic structure contour, isopach, overburden thickness, ash yield, sulfur content, calorific value, and selected trace-element contents; and public domain geochemical and stratigraphic databases. The assessment methodology and a few results are presented.

  10. Existing concepts of the formation of the Northern Czech lignite basin

    Nurnik, S.


    In the Myocene period, the area of sediment accumulation occupied three times more area than the region of the basin's denudation. The Krushnyye Mountains and Czech Midland did not yet exist as orographic units. These morphostructures arose in the Pleistocene epoch. Both morphostructures are currently considered to be an integral part of the large fold.

  11. Fluvio-lacustrine sedimentation and volcanism in a Late Carboniferous tensional intra-arc basin, northern Chile

    Breitkreuz, Christoph


    Extensive outcrops of Late Carboniferous to Triassic volcanoplutonic magnetic-arc complexes occur in the Andes of northern Chile. In the Salar de Atacama area, terrestrial volcanosedimentary successions include a 200-600 m thick fluvio-lacustrine sequence ("Miembro Medio"). The terrestrial basin which accommodated this sequence formed during the latest Carboniferous on top of the deposits of the pre-existing Carboniferous composite volcanoes. The lower part of the Miembro Medio consists of green limnic and multicoloured alluvial fan deposits; the upper part is made up of red fluvial sedimentary rocks. Basic volcanic rocks occur locally throughout the sequence. The climate is inferred to have been warm and humid. The limnic (freshwater) environment had a minimum extension of 300 × 100 km. Limnic facies is inferred from the existence of fine-parallel-bedded sediments, ooliths and a limnic benthic fauna. Lake-shore deposits prevail in the outcrops. In some sections, the green limnic sequence is followed by red fine-grained floodplain or alluvial plain, and fluvial channel deposits. The framework composition of the Miembro Medio is dominated by volcanogenic detritus presumably eroded from the successions of the previous Late Carboniferous volcanic arc. Another volcanogenic clast type was provided by syndepositional basalto-andesitic phreatomagmatic activity, which also produced peperitic sills, dykes and lavas. The limnic-alluvial fan facies association, the predominance of volcanogenic detritus, and the accompanying intrabasinal basic calc-alkaline volcanism together with the considerable size of the basin point to a ?NW-SE trending half-graben setting controlled by (trans-)tensional arc tectonics. With regard to the Late Carboniferous-Triassic volcanosedimentary successions of northern Chile, this Latest Carboniferous tensional setting is the only feature in this area supporting those models, which inferred an extensional magmatic arc for the entire Central and

  12. Late Quaternary faulting on the Manas and Hutubi reverse faults in the northern foreland basin of Tian Shan, China

    Gong, Zhijun; Li, Sheng-Hua; Li, Bo


    The Tian Shan Range lies in the actively deforming part of the India-Asia collision zone. In the northern foreland basin of Tian Shan, the strata were intensively deformed by Cenozoic folding and faulting. Slip rate studies along these faults are important for understanding the dynamics of crustal deformation and evaluating the seismic hazards in the region. Two reverse faults (the Manas and Hutubi faults) in the northern foreland basin were investigated. Due to past faulting events along these faults, the terrace treads along the Manas River were ruptured, forming fault scarps several meters in height. Loess deposits were trapped and preserved at the surface ruptures along these scarps. The thickness of the trapped loess is dependent on the size of the ruptures. The minimum and maximum ages of these scarps are constrained by dating the loess preserved at the surface ruptures and the terrace treads, respectively, using the quartz optically stimulated luminescence (OSL) dating technique. Our dating results suggest that the loess trapped at the ruptures was deposited from the early to mid-Holocene at the Hutubi Fault, and from the mid- to late-Holocene at the Manas Fault. The vertical displacements of the faults were evaluated by measuring the topographic profiles across the investigated fault scarps using the differential global position system (DGPS). Our results suggest that, during the late Quaternary in the studied region, the vertical slip rates of the Manas Fault were between ˜ 0.74 mm /yr and ˜ 1.6 mm /yr, while the Hutubi Fault had a much lower vertical slip rate between ˜ 0.34 mm /yr and ˜ 0.40 mm /yr. The tectonic implications of our results are discussed.

  13. What drives basin scale spatial variability of snowpack properties in northern Colorado?

    Sexstone, G. A.; Fassnacht, S. R.


    This study uses a combination of field measurements and Natural Resource Conservation Service (NRCS) operational snow data to understand the drivers of snow density and snow water equivalent (SWE) variability at the basin scale (100s to 1000s km2). Historic snow course snowpack density observations were analyzed within a multiple linear regression snow density model to estimate SWE directly from snow depth measurements. Snow surveys were completed on or about 1 April 2011 and 2012 and combined with NRCS operational measurements to investigate the spatial variability of SWE near peak snow accumulation. Bivariate relations and multiple linear regression models were developed to understand the relation of snow density and SWE with terrain variables (derived using a geographic information system (GIS)). Snow density variability was best explained by day of year, snow depth, UTM Easting, and elevation. Calculation of SWE directly from snow depth measurement using the snow density model has strong statistical performance, and model validation suggests the model is transferable to independent data within the bounds of the original data set. This pathway of estimating SWE directly from snow depth measurement is useful when evaluating snowpack properties at the basin scale, where many time-consuming measurements of SWE are often not feasible. A comparison with a previously developed snow density model shows that calibrating a snow density model to a specific basin can provide improvement of SWE estimation at this scale, and should be considered for future basin scale analyses. During both water year (WY) 2011 and 2012, elevation and location (UTM Easting and/or UTM Northing) were the most important SWE model variables, suggesting that orographic precipitation and storm track patterns are likely driving basin scale SWE variability. Terrain curvature was also shown to be an important variable, but to a lesser extent at the scale of interest.

  14. Characteristics of high arsenic groundwater in Hetao Basin, Inner Mongolia, northern China

    YangChun Zhu; XueYong Zhao; Min Chen; YongQing Luo; Xin Zhou


    It is well known that the Hetao Basin is one of the most seriously arsenic-affected groundwater areas in China. In order to understand the characteristics of high arsenic (As) groundwater in the Basin, a brief overview of arsenic in groundwater follows. High arsenic in the Basin commonly occurs in shallow groundwater and the total arsenic concentrations range from 0.58 to 572 µg/L (average 99.73 µg/L), exceeding the maximum mandated value of 10 µg/L for drinking water in China;As(Ш) is the predominant species. The regional distribution pattern of arsenic in the groundwater increases from south/southeast to north/northwest. Hangjinhouqi and Wuyuan counties are considered as the most seriously affected areas, with high incidences of endemic arsenicosic diseases in the Hetao Basin. High groundwater arsenic correlates with the increase of well depth. Previous studies proposed that groundwater arsenic in the Basin is mainly originated from desorption of some natural solid materials in the sediments, under reducing condition. Generally, reducing condition is believed to be the primary factor for arsenic releasing from the sediment to groundwater in the region. Under inorganic or bacterial processes, Fe2O3 changes to FeS and arsenic adsorbed to Fe(OH)3 dissolves into groundwater, and As(V) is re-duced to As(Ш). Besides, reducing environments, groundwater hydraulic gradients, organic matter, pH, evapotranspiration, and soil texture are presumed to be the predominant factors that control arsenic mobilization.

  15. Unroofing around Qaidam Basin of northern Tibet at 30 Ma:constraints from 40Ar/39Ar and FT thermochronology on granitoids

    王非; 罗清华; 李齐; 万京林; 郑德文; 王二七


    An 40Ar/39Ar and fission track thermochronological study has been carried out on three suites of granitoids collected along the northern and southern edges of the Qaidam Basin to better constrain the mechanisms accommodating the India-Asia collision around the Qaidam Basin (northern Tibet), in order to understand the evolution of the entire deformation area. Mica and K-feldspar have been analyzed and the cooling histories of the latter have been modeled. The cooling histories based upon K-feldspar modeling and fission track ages show that samples simultaneously recorded an important cooling event (7.5-10.7℃/Ma) around 30 Ma, which is thought to reflect an increase of denudation rate related to the tectonic activity in this area associated with uplift suggesting significant crustal thickening starting around 30 Ma in this area. The estimated sedimentation rate in the Qaidam Basin, the propagation rate along the Altyn Tagh fault and field observations support this deduction.

  16. The importance of diverse data types to calibrate a watershed model of the Trout Lake Basin, Northern Wisconsin, USA

    Hunt, Randall J.; Feinstein, Daniel T.; Pint, Christine D.; Anderson, Mary P.


    As part of the USGS Water, Energy, and Biogeochemical Budgets project and the NSF Long-Term Ecological Research work, a parameter estimation code was used to calibrate a deterministic groundwater flow model of the Trout Lake Basin in northern Wisconsin. Observations included traditional calibration targets (head, lake stage, and baseflow observations) as well as unconventional targets such as groundwater flows to and from lakes, depth of a lake water plume, and time of travel. The unconventional data types were important for parameter estimation convergence and allowed the development of a more detailed parameterization capable of resolving model objectives with well-constrained parameter values. Independent estimates of groundwater inflow to lakes were most important for constraining lakebed leakance and the depth of the lake water plume was important for determining hydraulic conductivity and conceptual aquifer layering. The most important target overall, however, was a conventional regional baseflow target that led to correct distribution of flow between sub-basins and the regional system during model calibration. The use of an automated parameter estimation code: (1) facilitated the calibration process by providing a quantitative assessment of the model's ability to match disparate observed data types; and (2) allowed assessment of the influence of observed targets on the calibration process. The model calibration required the use of a 'universal' parameter estimation code in order to include all types of observations in the objective function. The methods described in this paper help address issues of watershed complexity and non-uniqueness common to deterministic watershed models.

  17. Seismic imaging and analysis of source and migration within an integrated hydrocarbon system study: Northern Gulf of Mexico Basin

    Gross, Oliver P.; Hood, Kenneth C.; Harrison, Stanley C. [Exxon Exploration Co., Houston, TX (United States); Wenger, Lloyd M. [Exxon Production Research Co., Houston, TX (United States)


    The sources for hydrocarbons in young Tertiary reservoirs of the offshore Gulf of Mexico have been enigmatic in the past due to the lack of source rock penetration in offshore drilling. Exxon formed a multidisciplinary team to address source, maturation, and migration in the northern Gulf of Mexico. The study was initiated in a pilot area east of the Mississippi River Delta where the complete hydrocarbon system can be seismically imaged, then expanded to the west across much of the shelf and slope. Hydrocarbons from seeps and reservoirs were geochemically characterized across the entire northern Gulf of Mexico Basin, and direct oil to source rock correlations were made both offshore (in pilot area) and onshore. Modern 2-D and 3-D seismic was used to develop a geologic framework and to map potential offshore source intervals. The major sources identified offshore are centered on the Eocene, Turonian, Tithonian, and Oxfordian, and correspond to second-order sequence stratigraphic transgressions. (author). 1 fig., 1 tab


    Attila IAKOB


    Full Text Available The past years showed to the world and to the European Union that classical approaches are not enough to be a power breaker in the Caucasian region, where the overlap of history, myth, and cultures creates a unique geopolitical context marked by century old grudges and imaginary or real socio-economical issues. It is clear that concepts like “ring of friends” or Eastern Partnership need a rebranding and an upgrade due to contemporary context changes. Russian expansion, Turkish political shifts, Ukrainian crisis, Iranian ambitions, Kurd issues, energy policies and socio-economical convulsions are defining the new shape of the geographical areas on both side of the Caucasus Mountain. In this context the European leadership needs to rethink the foreign policy approach to the region and to create a new set of actions in this context. This difficult task is needed not only from the perspective of Europe’s energetic security but from the point of regional stability, because Europe and its global development depend on its involvement in the neighboring regions. From this perspective our paper would like to analyze and create a realistic image on the dynamic of the relations of EU with the countries in this region and the perspectives in the contemporary context where the overlapping geopolitical interests are making this region a key one for several future issues.

  19. Interactions between basement and cover during the evolution of the Salar de Atacama Basin, northern Chile

    Nelson Muñoz; Reynaldo Charrier; Teresa Jordan


    ABSTRACT A reinterpretation of the structural style on the eastern Cordillera Domeyko and the adjacent Salar de Atacama Basin reveals the existence of west-dipping, high-angle, thrust-faults extending below the Cordillera Domeyko and Cordón de Lila, resulting from inversion of Cretaceous extensional faults, that transferred west-ward their displacement into the cover, generating fault-propagation and detachment folds. The most conspicuous of these structures is the Cordillera de la Sal. Contr...




    To determine to what extent climate change affects the rainfall recorded on the southern Mediterranean basin, a trend analysis is proposed. This study is based on the chronological graphic method of processing information (MGCTI) of type "Matrice Bertin". Results show an extreme variability of the precipitations and a severe drought, especially for Morocco, observed since 1970s. Finally, a gradual return to humid conditions is observed from the beginning of the 2000s in Algeria and Tunisia an...

  1. Effects of precipitation and potential evaporation on actual evapotranspiration over the Laohahe basin, northern China

    Y. LIU; L Ren; X. Yang; M. Ma; Yuan, F.; Jiang, S.


    Problems associated with water scarcity are facing new challenges under the climate change. As one of main consumptions in water cycle on the Earth, evapotranspiration plays a crucial role in regional water budget. In this paper, we employ two methods, i.e. hydrological sensitivity analysis and hydrological model simulation, to investigate the effect of climate variability and climatic change on actual evapotranspiration (Ea) within the Laohahe basin during 1964–2009. Calibr...

  2. Chronostatigraphic basin framework for Palaeoproterozoic rocks (1730-1575 Ma) in northern Australia and implications of base-metal mineralisation

    The new chronostratigraphic subdivision for Palaeoproterozoic rocks of northern Australia provides an improved framework for future resource exploration. The nine supersequence boundaries identified in the ca 1730-1575Ma Calvert and Isa Superbasins enable the timing of major tectonic events and their stratigraphic response to be better understood. Third- and 4th-order sequence boundaries facilitate the determination of stratigraphic architecture, ultimately providing the necessary information for constraining the flow of fluids in these basins. SHRIMP zircon ages are essential for determining the magnitude of depositional hiatuses at supersequence and some sequence boundaries, and together with palaeomagnetic data provide independent age constraints for the sequence interpretations. Pb/Pb model ages for the world class Broken Hill, Mt Isa, McArthur River and Century Zn Pb Ag deposits coincide with tectonic events recorded at the Gun, Loretta, River Supersequence boundaries and the superbasin boundary formed during closure of the Isa Superbasin during D2 at Mt Isa. The coincidence of a Pb/Pb model age for Broken Hill with an apparent polar wander path inflection at the Gun Supersequence boundary indicates that the regional chronostratigraphic basin framework developed for northern Australia is applicable to rocks of similar age elsewhere in Australia. Furthermore, if the ultimate cause of these inflections is interplate stress, the basin framework should be globally applicable. Hand-held spectrometers provide an efficient and cost-effective method for collecting gamma-ray data from outcrops. The resulting gamma-ray curves permit more accurate correlation with subsurface stratigraphies and together with facies information facilitate the identification of stratigraphic sequences and their bounding stratal surfaces, the essential building blocks of regional chronostratigraphic correlations. Contrary to general belief most of the sections measured in this study preserve


    Kotti, B K


    There are 116 species of fleas in the territory of the Great Caucasus. 21 species are parasites of birds, others are the fleas of mammals. Among 41 genera of Caucasus' fauna only Caenopsylla, Phaenopsylla and Araeopsylla are absent in the Great Caucasus. There are 11 endemic species. Fleas of 66 species are distributed along all mountain system. Parasites of some birds and carnivorous mammals, insectivores and rodents live from lowlands till highlands. Some species are living at the forest altitudinal belt, others prefer the foothills and the mid-height areas; they are absent atthe highlands. Their hosts may live at all longitudinal belts; the distribution of other species is limited to lowlands in accordance with distribution of their main hosts. PMID:26827488

  4. Thermochronological evolution of the Eastern Pontides and the Eastern Anatolian Plateau and NW Lesser Caucasus (Turkey, Georgia, Armenia)

    Albino, Irene


    The analysis of apatite fission tracks is applied to the study of the syn- and post-collisional thermochronological evolution of a vast area that includes the Eastern Pontides, their continuation in the Lesser Caucasus of Georgia (Adjara-Trialeti zone) and northern Armenia, and the eastern Anatolian Plateau. The resulting database is then integrated with the data presented by Okay et al. (2010) for the Bitlis Pütürge Massif, i.e. the western portion of the Bitlis-Zagros collision zone between...

  5. Caucasus and the petroleum stakes of Caspian Sea

    The splitting of the former USSR block in 1991 has generated a shock wave in the Caucasus area with the will of all ex-soviet republics to reach their complete independence. Because of the historical and geographical complexity of Caucasus, both geopolitical and human, this disorder has generated even more hazardous results, enhanced by the coveted oil and gas reserves of the Caspian Sea. This article analyses the petroleum stakes as factors of rivalry and instability (sovereignty of oil and gas fields, rivalries about the exploitation and transport of hydrocarbons), but also as factors of cooperation and re-composition. (J.S.)




    Full Text Available To determine to what extent climate change affects the rainfall recorded on the southern Mediterranean basin, a trend analysis is proposed. This study is based on the chronological graphic method of processing information (MGCTI of type "Matrice Bertin". Results show an extreme variability of the precipitations and a severe drought, especially for Morocco, observed since 1970s. Finally, a gradual return to humid conditions is observed from the beginning of the 2000s in Algeria and Tunisia and since 2008 in Morocco. This new trend is also confirmed by recent results provided by agricultural data of 2011/2012 and 2012/2013.

  7. Hydrogeochemistry of high iodine groundwater: a case study at the Datong Basin, northern China.

    Li, Junxia; Wang, Yanxin; Xie, Xianjun; Zhang, Liping; Guo, Wei


    High iodine concentrations in groundwater have seldom been reported and there have been few systematic studies on high iodine groundwater worldwide. To better understand the sources and processes responsible for iodine enrichment in the groundwater of the Datong Basin, the hydrochemical characteristics of groundwater and geochemical features of aquifer sediments were studied. High iodine groundwater mainly occurs in the center of the Datong Basin with iodine concentrations ranging between 3.31 and 1890 μg L(-1). Most samples with iodine concentrations higher than 500 μg L(-1) are from wells with depths between 75 and 120 m. High pH and a reducing environment are favorable for iodine enrichment in the groundwater, with iodide as the dominant species that accounts for 63.2-99.3% of the total iodine. Sediment samples from a borehole specifically drilled for this study contain 0.18-1.46 mg kg(-1) iodine that is moderately correlated with total organic carbon (TOC). The results of sequential extraction experiments show that iodine is mostly bound to iron oxyhydroxides and organic matter in the sediments. The mobilization processes of iodine are proposed to include reductive dissolution of iron oxyhydroxides and transformations among iodide, iodate and organic iodine driven by microbial activities under alkaline and reducing conditions. PMID:23478640

  8. Snow cover dynamics and hydrological regime of the Hunza River basin, Karakoram Range, Northern Pakistan

    A. A. Tahir


    Full Text Available A major proportion of flow in the Indus River is contributed by its snow- and glacier-fed river catchments situated in the Himalaya, Karakoram and Hindukush ranges. It is therefore essential to understand the cryosphere dynamics in this area for water resource management. The MODIS MOD10A2 remote-sensing database of snow cover products from March 2000 to December 2009 was selected to analyse the snow cover changes in the Hunza River basin (the snow- and glacier-fed sub-catchment of the Indus River. A database of daily flows for the Hunza River at Dainyor Bridge over a period of 40 yr and climate data (precipitation and temperature for 10 yr from three meteorological stations within the catchment was made available to investigate the hydrological regime in the area. Analysis of remotely sensed cryosphere (snow and ice cover data during the last decade (2000–2009 suggest a rather slight expansion of cryosphere in the area in contrast to most of the regions in the world where glaciers are melting rapidly. This increase in snow cover may be the result of an increase in winter precipitation caused by westerly circulation. The impact of global warming is not effective because a large part of the basin area lies under high altitudes where the temperature remains negative throughout most of the year.


    Robert Jacobi; John Fountain


    In the structure task, we completed a N-S transect east of Seneca Lake that indicated a N-striking fault near the southeastern shore of Seneca Lake, and also indicated NE and ENE-trending FIDs and faults north of Valois. The orientation and existence of the NE-striking FIDs and faults are thought to be controlled by basement faults, rather than thrust ramps above the Salina salt controlled only by a far-field Alleghanian stress field. Structure contour maps based on well log analyses have been constructed but not interpreted. Soil gas data displayed a number of ethane-charged soil gas ''spikes'' on a N-S transect from Ovid south to near Valois. The soil gas team found a larger number of spikes in the northern half of the survey, suggesting more open fractures (and faults) in the northern half of the survey. Seismic data has been purchased and reprocessed. Several grabens observed in the Trenton reflector are consistent with surface structure, soil gas, and aeromagnetic anomalies. The aeromagnetic survey is completed and the data is processed. Prominent magnetic anomalies suggest that faults in the Precambrian basement are located beneath regions where grabens in the Trenton are located.

  10. Interactions between basement and cover during the evolution of the Salar de Atacama Basin, northern Chile

    Nelson Muñoz


    Full Text Available ABSTRACT A reinterpretation of the structural style on the eastern Cordillera Domeyko and the adjacent Salar de Atacama Basin reveals the existence of west-dipping, high-angle, thrust-faults extending below the Cordillera Domeyko and Cordón de Lila, resulting from inversion of Cretaceous extensional faults, that transferred west-ward their displacement into the cover, generating fault-propagation and detachment folds. The most conspicuous of these structures is the Cordillera de la Sal. Contractional structures in the Cordillera Domeyko involved a Paleozoic crystalline, volcanic, and sedimentary, uplifted basement. Seismic reflection sections and available surface geology allows to study the interactions between development of the thick-skinned basement structures, sedimentation within the basin, and the thin-skinned deformation in the sedimentary cover. Geometry of the units in the basin continuously modified. Anticline growth above basement thrust-faults locally controlled syn-thrusting sequences, and generated progressive unconformities. Stratigraphic architecture in the basin seems to have been mainly controlled by tectonic activity. Tectonism generated accommodation space, altered base levels, and controlled source areas. The stratigraphy and geometry of the basin deposits resulted mainly from the succession of the following events: local extensional subsidence during the Early to Late Cretaceous, uplift of the Cordillera Domeyko during the latest Cretaceous to Miocene, uplift of the Puna, and subsidence probably caused by flexural response of the lithosphere during thrust-sheet loading, and sediment accumulationRESUMEN Interacciones entre el basamento y la cobertura durante la evolución de la Cuenca del Salar de Atacama, norte de Chile. La reinterpretación del estilo estructural del borde oriental de la Cordillera Domeyko y de la adyacente cuenca del Salar de Atacama, basada en el análisis de la geología de superficie y de perfiles s

  11. Tectonics and paleogeography of the Marajó Basin, northern Brazil



    Full Text Available The Marajó Basin area presents geologic and geomorphologic features chiefly due to the Mesozoic extension and post-Miocene neotectonics. The extension event with an Early and a Late Cretaceous phases originated four sub-basins that constitutes the Marajó Basin, with a thick continental clastic sequence showing marine influence. NW and NNW normal faults and NE and ENE strike-slip faults controlled the basin geometry. The extension, related to the Equatorial Atlantic opening, propagated into the continent along crustal weakness zones of the Precambrian Tumucumaque, Amapá and Araguaia orogenic belts. The neotectonic event is a strike-slip regime which developed transtensional basins filled in by Upper Tertiary shallow marine (Pirabas Formation and transitional sequences (Barreiras Group, followed by Quaternary fluvial deposits and transitional sequences derived from the Amazon and Tocantins rivers and the Marajoara estuary. The current landscape has a typical estuarine morphology. The coast morphology presents sea-cliffs on transitional Upper Tertiary sequences, while inwards dominate hills sustained by Mid-Pleistocene lateritic crust, with a flat erosive surface at 70 m. In the eastern Marajó Island several generations of paleochannels associated with fluvial-estuarine sequences are recognized, while a fluvial-marine plain is widespread on its western side.A área da Bacia do Marajó apresenta feições geológicas e geomorfológicas devidas principamente à distensão Mesozóica e à neotectônica pós-miocênica. O evento de distensão, com fases do Cretáceo Inferior e Superior, originou quatro sub-bacias que contituem a Bacia do Marajó, com uma espessa seqüência clástica continental mostrando influência marinha. Falhas normais NW e NNW e direcionais NE e ENE controlaram a geometria da bacia. A distensão, relacionada com a abertura do Atlântico Equatorial, propagou-se continente adentro ao longo de zonas de fraqueza crustal dos

  12. Spatio-temporal snow cover change and hydrological characteristics of the Astore, Gilgit and Hunza river basins (western Himalayas, Hindukush and Karakoram region) - Northern Pakistan

    Tahir, Adnan Ahmad; Chevallier, Pierre; Arnaud, Yves; Lane, Stuart; Terzago, Silvia; Adamowski, Jan Franklin


    A large proportion of Pakistan's irrigation water supply is drawn from the Upper Indus River Basin (UIB) situated in the Himalaya-Karakoram-Hindukush (HKH) ranges. More than half of the annual flow in the UIB is contributed by five of its high-altitude snow and glacier-fed sub-basins including the Astore (Western Himalaya - southern part of the UIB), Gilgit (Hindukush - western part of the UIB) and Hunza (Central Karakoram - northern part of the UIB) River basins. Studying the snow cover, its spatio-temporal evolution and the hydrological response of these sub-basins is important so as to better manage water resources. This study compares data from the Astore, Gilgit and Hunza River basins (mean catchment elevation, 4100, 4250 and 4650 m ASL, respectively), obtained using MODIS satellite snow cover images. The hydrological regime of these sub-catchments was analyzed using hydrological and climate data available at different altitudes from the basin areas. The results suggest that the UIB is a region undergoing a stable or slightly increasing trend of snow cover in the southern (Western Himalayas), western (Hindukush) and northern (Central Karakoram) parts. Discharge from the UIB is a combination of snow and glacier melt with rainfall-runoff in the southern part, but snow and glacier melt is dominant in the northern and western parts of the catchment. Despite similar snow cover trends (stable or slightly increasing), different river flow trends (increasing in Astore and Gilgit, decreasing in Hunza) suggest that a sub-catchment level study of the UIB is needed to understand thoroughly its hydrological behavior for better flood forecasting and water resources management and to quantify how the system is being forced by changing climate.

  13. Sedimentological and geochronological evidences of anthropogenic impacts on river basins in the Northern Latium coastal area (Italy)

    Piazzolla, Daniele; Paladini de Mendoza, Francesco; Scanu, Sergio; Marcelli, Marco


    In this work we aimed to compare sedimentological and geochronological data from three sediment core samples (MIG50, MRT50, and GRT50) taken in the Northern Latium (Italy) coastal area, at -50 m depth, to data regarding rainfall, river flows and the land use in the three most important hydrographic basins (Mignone, Marta and Fiora) and in the coastal area. Different trends of sediment mass accumulation rate (MAR) are detected in the three cores: a strongly increasing trend was identified in MIG50 and MRT50 cores while GRT50 doesn't show significant variation. Data from the sedimentological analysis of GRT50 core identify a progressive decrease in the sandy component, which declined from about 30% to the current level of 7% over the last 36 years, while MRT50 and MIG50 cores (mainly composed by pelitic fraction > 95%) showed slight variations of textural ratio between silt and clay. According to the general decrease of pluviometric trend observed in Italy, related to teleconnection pattern tendency (NAO), the statistical analysis of rain identified significative decrease only in the Fiora river basin, whereas in the other two locations the decrease was not as significant. Regarding the Fiora river flow, a significative decreasing trend of average flow is detected, while the flood regime remained unaffected over the past 30 years. The analysis of the land use shows that the human activities are increased of 6-10% over the available time steps (1990 - 2006) in Fiora and Mignone river basins, while the Marta river basin has a strong human impact since 1990 highligting more than 80% of artificial soil covering. The largest variation is observed on the Fiora basin (10%) where the antrhopic activities have expanded to an area of about 85 Km2. Moreover, in the last ten years a large beach nourishment in 2004 (570000 m3) and dredging activities in the early second half of 2000s (1000000 m3 moved) were performed in Marina di Tarquinia beach and in front of the Torrevaldaliga

  14. Two new species of Pseudancistrus (Siluriformes, Loricariidae from the Amazon basin, northern Brazil

    Gabriel da Costa e Silva


    Full Text Available Two new species of Pseudancistrus, a genus diagnosed by non-evertible cheek plates and hypertrophied odontodes along the snout margin, are described from two drainages of the Brazilian Shield: P. kayabi from the rio Teles Pires (rio Tapajós basin and P. asurini from the rio Xingu. The new species are distinguished from congeners (P. barbatus, P. corantijniensis, P. depressus, P. nigrescens, P. reus, and P. zawadzkii by the coloration pattern. Pseudancistrus kayabi has dark bars on the dorsal and caudal fins which are similar to that of P. reus from the Caroní River, Venezuela. Pseudancistrus asurini is unique among Pseudancistrus in having whitish tips of the dorsal and caudal fins in juveniles to medium-sized adults.

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

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


    elements provide a hint at a prevailing subsidence regime and effective sediment supply into the basin that clearly contrast with the conveyed idea of a sediment-starved and tectonic stable shelf. They naturally raise questions about the nature and origin of sediment supply, since no significant point siliciclastic fluvial source flows directly into the shelf. Stemming from that, we are forced to speculate about: (A) the role of neotectonic movements involving the Serra do Mar coastal mountain ranges to potentially source clastic influx into the basin during the Quaternary, or about the real importance of secondary drainage basins debouching today; and (B) the mechanical nature of a supposed subsidence during the Pliocene and the Quaternary time span (overloading ? sediment compaction ? thermal cooling ?). The interpretation of industrial seismic lines can provide the answers of many of these questions. The next step of this work is to make a stratigraphy model of the sedimentary systems of Santos basin to understand how the ancient creation of accommodation space can influence the recent sedimentary architecture and how is the change in sedimentary influx and the sedimentary records of different orders of cyclicity.

  16. Organic geochemical characterisation of shallow marine Cretaceous formations from Yola Sub-basin, Northern Benue Trough, NE Nigeria

    Sarki Yandoka, Babangida M.; Abdullah, Wan Hasiah; Abubakar, M. B.; Hakimi, Mohammed Hail; Jauro, Aliyu; Adegoke, Adebanji Kayode


    The shallow marine shales of the Cretaceous formations namely Yolde, Dukul, Jessu, Sekuliye and Numanha ranging in age from Cenomanian to Coniacian within the Yola Sub-basin in the Northern Benue Trough, northeastern Nigeria were analysed to provide an overview on their hydrocarbon generation potential. This study is based on pyrolysis analysis, total organic carbon content (TOC), extractable organic matter (EOM), biomarker distributions and measured vitrinite reflectance. The present-day TOC contents range between 0.24 and 0.71 wt. % and Hydrogen Index (HI) values between 8.7 and 113 mg HC/g TOC with Type III/IV kerogens. Based on the present-day kerogen typing, the shale sediments are expected to generate mainly gas. Biomarker compositions indicates deposition in a marine environment under suboxic conditions with prevalent contribution of aquatic organic matter and a significant amount of terrigenous organic matter input. Organic matter that is dominated by marine components contains kerogens of Type II and Type II-III. This study shows that the organic matter has been affected by volcanic intrusion and consequently, have reached post-mature stage of oil generation. These higher thermal maturities levels are consistent with the vitrinite reflectance ranging from 0.85 to 2.35 Ro % and high Tmax (440-508 °C) values as supported by biomarker maturity ratios. Based on this study, a high prospect for major gas and minor oil generation potential is anticipated from the shallow marine Cretaceous formations from Yola Sub-basin.

  17. Late Pleistocene shortening rate on the northern margin of the Yanqi Basin, southeastern Tian Shan, NW China

    Huang, Wei-liang; Yang, Xiao-ping; Li, An; Pierce, Ian K. D.; Thompson, Jessica A.; Angster, Stephen J.; Zhang, Ling


    How strain is distributed and partitioned on individual faults and folds on the margins of intermontane basins remains poorly understood. The Haermodun (Ha) anticline, located along the northern margin of the intermontane Yanqi Basin on the southeastern flank of the Tian Shan, preserves flights of passively deformed alluvial terraces. These terraces cross the active anticline and can be used to constrain local crustal shortening and uplift rates. Geologic and geomorphic mapping, in conjunction with high-resolution dGPS topographic surveys, reveal that the terrace surfaces are perpendicular to the fold's strike, and display increased rotation with age, implying that the anticline has grown by progressive limb rotation. Combined with the open sinusoidal curve model and excess area method, we calculated uplift and shortening values for each terrace since abandonment. Using the published exposure ages of each terrace, we found the vertical uplift rate gradually decreased from ∼0.43 to ∼0.11 mm/a, whereas the shortening rate remained constant at ∼0.3 mm/a since the anticline began to grow. A fresh fault scarp, 0.4 ± 0.1 m high, is visible along the southern portion of the Ha anticline, and is interpreted to be the most recent evidence of seismic activity. Using an estimated rupture area and the length of the fresh offset created by this earthquake, we estimate that the main thrust underlying the Ha anticline has generated moderate (M < 7) earthquakes in the past. The shortening rates of the Ha anticline from geomorphology agree with current GPS measurements cover-over the fold, and highlight the importance of determining slip rates for individual faults in order to resolve patterns of strain distribution across intermontane belts.

  18. Occurrence, behavior and distribution of high levels of uranium in shallow groundwater at Datong basin, northern China

    Geochemical investigations of uranium (U) occurrence in the environments were conducted at Datong basin of northern China. The results suggest that U contents were generally 22+) species is dominant and strongly adsorbed onto iron (hydro)xides, while it would be preferentially complexed with carbonate in the alkaline groundwater, forming highly soluble uranyl-carbonate complexes at Datong. Under reducing conditions, uranous (U(IV)) species is ready to precipitate or bind to organic matter, therefore having a low mobility. At the study area, high U groundwater (> 30 μg/L) occurs at the alluvial plains due to intermediate redox and enhanced alkaline conditions. The abnormally high levels of U in groundwater (> 100 μg/L) are locally found at the west alluvial plains. By contrast, U co-precipitation with secondary carbonate minerals like Ca2UO2(CO3)3 in the dominant Ca–Mg–Na–HCO3 type groundwater may prevail at the east alluvial plains. Besides, bedrocks such as Carboniferous and Permian sedimentary rocks, especially the coal-bearing strata which have higher U contents at the west mountain areas may also account for the abnormally high levels of U in groundwater. - Highlights: • High U groundwater occurs at the alluvial plains of Datong basin. • Redox state, complexation and adsorption are responsible for U enrichment. • Carboniferous and Permian sedimentary rocks have higher U contents at Datong. • Uranyl is preferentially complexed with carbonate in groundwater. • U in the aquifer sediments may be primarily associated with carnotite


    А. А. Dobrynina


    Full Text Available This paper presents results of the study of attenuation of seismic waves in the lithosphere and upper mantle of the northern part of the Basin and Range Province (BRP (Fig. 1. In this study, the coda-wave method [Aki, Chouet, 1975] is applied to process data collected in the seismic experiment conducted in 1988–1989, PASSCAL Basin and Range Passive Seismic Experiment [Owens, Randall, 1989], including records of 66 earthquakes and explosions (Mb=1.1–5.0 which occurred in BRP (Fig. 2.The effective seismic quality factor by the coda is calculated using the single-backscattering model [Aki, Chouet, 1975]. The QC values are calculated for 18 values of the lapse time window W from 10 to 95 sec with the step of 5 sec at six (6 central frequencies (0.3, 0.75, 1.5, 3.0, 6.0, and 12.0 Hz. In total, 7776 individual measurements of QC were done. It is observed that the quality factor QC is strongly dependent on the frequency and the lapse time window W: QC increases from 12±6 to 359±17 for the central frequencies of 0.3 and 12.0 Hz when the lapse time window is W=10 sec and from 87±6 to 1177±87 for the same frequencies when W=95 sec (Fig. 6. On the basis of the QС values obtained for all the lapse time windows W empirical relationships of quality factors and frequencies are calculated according to [Mitchell, 1981], and values of quality factor Q0 at reference frequency f0 (f0=1 Hz and frequency parameter n (which is close to 1 and varies depending on the heterogeneity of the medium [Aki, 1981] are obtained. In this study, Q0 varies from 60±8 to 222±17, the frequency parameter ranges from 0.57±0.04 to 0.84±0.05, and the attenuation coefficient δ varies from 0.015 to 0.004 km–1, depending on W (Fig. 8; similar values of attenuation parameters are typical of regions with high tectonic activity [Mak et al., 2004].In the single-backscattering model, the dependence of the attenuation parameters from the lapse time window can be explained in terms

  20. Military co-operation with South Caucasus countries / Rafal Seniuch

    Seniuch, Rafal


    Ettekanne Poola ja Lõuna-Kaukaasia vabariikide vahelisest sõjalis-poliitilisest koostööst 22.-23. septembrini 2003 Vilniuses toimunud seminaril "South Caucasus: making the best use of external assistance for stability building and for co-operation with NATO"


    Bubenok, Oleg


    This article takes a look at the formation of the Ossetian ethnos in the Southern Caucasus. The author attempts to analyze the different approaches to this issue, particularly those relating to the ethnogenesis and identification of the Ossets, and to coordinate these processes with possible ways to settle the South Osset-Georgian ethnopolitical conflict.

  2. Seismic reflection-based evidence of a transfer zone between the Wagner and Consag basins: implications for defining the structural geometry of the northern Gulf of California

    González-Escobar, Mario; Suárez-Vidal, Francisco; Hernández-Pérez, José Antonio; Martín-Barajas, Arturo


    This study examines the structural characteristics of the northern Gulf of California by processing and interpreting ca. 415 km of two-dimensional multi-channel seismic reflection lines (data property of Petróleos Mexicanos PEMEX) collected in the vicinity of the border between the Wagner and Consag basins. The two basins appear to be a link between the Delfín Superior Basin to the south, and the Cerro Prieto Basin to the north in the Mexicali-Imperial Valley along the Pacific-North America plate boundary. The seismic data are consistent with existing knowledge of four main structures (master faults) in the region, i.e., the Percebo, Santa María, Consag Sur, and Wagner Sur faults. The Wagner and Consag basins are delimited to the east by the Wagner Sur Fault, and to the west by the Consag Sur Fault. The Percebo Fault borders the western margin of the modern Wagner Basin depocenter, and is oriented N10°W, dipping (on average) ˜40° to the northeast. The trace of the Santa María Fault located in the Wagner Basin strikes N19°W, dipping ˜40° to the west. The Consag Sur Fault is oriented N14°W, and dips ˜42° to the east over a distance of 21 km. To the east of the study area, the Wagner Sur Fault almost parallels the Consag Sur Fault over a distance of ˜86 km, and is oriented N10°W with an average dip of 59° to the east. Moreover, the data provide new evidence that the Wagner Fault is discontinuous between the two basins, and that its structure is more complex than previously reported. A structural high separates the northern Consag Basin from the southern Wagner Basin, comprising several secondary faults oriented NE oblique to the main faults of N-S direction. These could represent a zone of accommodation, or transfer zone, where extension could be transferred from the Wagner to the Consag Basin, or vice versa. This area shows no acoustic basement and/or intrusive body, which is consistent with existing gravimetric and magnetic data for the region.

  3. Did Oligocene crustal thickening precede basin development in northern Thailand? A geochronological reassessment of Doi Inthanon and Doi Suthep

    Gardiner, Nicholas J.; Roberts, Nick M. W.; Morley, Christopher K.; Searle, Michael P.; Whitehouse, Martin J.


    The Doi Inthanon and Doi Suthep metamorphic core complexes in northern Thailand are comprised of amphibolite-grade migmatitic gneisses mantled by lower-grade mylonites and metasedimentary sequences, thought to represent Cordilleran-style core complexes exhumed through the mobilization of a low-angle detachment fault. Previous studies have interpreted two metamorphic events (Late Triassic and Late Cretaceous), followed by ductile extension between the late Eocene and late Oligocene, a model which infers movement on the detachment at ca. 40 Ma, and which culminates in a rapid unroofing of the complexes in the early Miocene. The Chiang Mai Basin, the largest such Cenozoic Basin in the region, lies immediately to the east. Its development is related to the extension observed at Doi Inthanon and Doi Suthep, however it is not definitively dated, and models for its development have difficulty reconciling Miocene cooling ages with Eocene detachment movement. Here we present new in-situ LA-ICP-MS and SIMS U-Pb age data of zircon and monazite grains from gneiss and leucogranite samples taken from Doi Inthanon and Doi Suthep. Our new zircon data exhibit an older age range of 221-210 Ma, with younger ages of ca. 72 Ma, and 32-26 Ma. Our monazite data imply an older age cluster at 83-67 Ma, and a younger age cluster of 34-24 Ma. While our data support the view of Indosinian basement being reworked in the Cretaceous, they also indicate a late Eocene-Oligocene tectonothermal event, resulting in prograde metamorphism and anatexis. We suggest that this later event is related to localized transpressional thickening associated with sinistral movement on the Mae Ping Fault, coupled with thickening at the restraining bend of the Mae Yuan Fault to the immediate west of Doi Inthanon. Further, this upper Oligocene age limit from our zircon and monazite data would imply a younger Miocene constraint on movement of the detachment, which, when combined with the previously recorded Miocene

  4. Benthic macro red alga:A new possible bio-precursor of Jurassic mudstone source rocks in the northern Qaidam Basin,northwestern China


    Whether benthic macroalga can be an important type of bio-precursor of source rocks is a contentious issue in source-rock studies,and has not been well understood.This paper represents a case study of Jurassic mudstone source rocks from the northern Qaidam Basin,northwestern China,in which the benthic macro red algae were recognized for the first time based on combined organic petrological and biomarker works.We found not only cystocarps in the algae,representative of rhodophyta,but also diahopanes,which are diagnostic biomarkers of such algae.Thus,as many reservoired oils in the northern Qaidam Basin contain abundant diahopanes,it may indicate that the red algae have contributed to hydrocarbon accumulation.This was confirmed by integrated geological and geochemical analyses.Hence,this study provides new evidence for macroalga-generated hydrocarbons.

  5. Growth of the Zagros Fold-Thrust Belt and Foreland Basin, Northern Iraq, Kurdistan

    Koshnaw, Renas; Horton, Brian; Stockli, Daniel; Barber, Douglas; Ghalib, Hafidh; Dara, Rebwar


    The Zagros orogenic belt in the Middle Eastern segment of the Alpine-Himalayan system is among the youngest seismically active continental collision zones on Earth. However, due to diachronous and incremental collision, the precise ages and kinematics of shortening and deposition remain poorly understood. The Kurdistan region of the Zagros fold-thrust belt and foreland basin contains well-preserved Neogene wedge-top and foredeep deposits that include clastic nonmarine fill of the Upper Fars, Lower Bakhtiari, and Upper Bakhtiari Formations. These deposits record significant information about orogenic growth, fold-thrust dynamics, and advance of the deformation front. Thermochronologic and geochronologic data from thrust sheets and stratigraphic archives combined with local earthquake data provide a unique opportunity to address the linkages between surface and subsurface geologic relationships. This research seeks to constrain the timing and geometry of exhumation and deformation by addressing two key questions: (1) Did the northwestern Zagros fold-thrust belt evolve from initial thin-skinned shortening to later thick-skinned deformation or vice-versa? (2) Did the fold-thrust belt advance steadily under critical/supercritical wedge conditions involving in-sequence thrusting or propagate intermittently under subcritical conditions with out-of-sequence deformation? From north to south, apatite (U-Th)/He ages from the Main Zagros Thrust, the Mountain Front Flexure (MFF), and additional frontal thrusts suggest rapid exhumation by ~10 Ma, ~5 Ma, and ~8 Ma respectively. Field observations and seismic sections indicate progressive tilting and development of growth strata within the Lower Bakhtiari Formation adjacent to the frontal thrusts and within the Upper Bakhtiari Formation near the MFF. In the Kurdistan region of Iraq, a regional balanced cross section constrained by new thermochronometric results, proprietary seismic reflection profiles, and earthquake hypocenters

  6. Quantification of effects of climate variations and human activities on runoff by a monthly water balance model: A case study of the Chaobai River basin in northern China

    Wang, G; Xia, J.; J. Che


    The Chaobai River basin in northern China consists of two major tributaries, the Chao River and Bai River. Monthly observations of precipitation, streamfiow, and panevaporation data are available for 35 years (1961-1966 and 1973-2001). Using the annual time series of the observed streamfiow, one break point at 1979 is detected and is adopted to divide the data set into two study periods, the "before" and "after" periods marking the onset of significant anthropogenic alteration of the flow (re...

  7. Middle to late Cenozoic basin evolution in the western Alborz Mountains: Implications for the onset of collisional deformation in northern Iran

    Guest, Bernard; Horton, Brian K.; Axen, Gary J.; Hassanzadeh, Jamshid; MCINTOSH, William C.


    Oligocene-Miocene strata preserved in synclinal outcrop belts of the western Alborz Mountains record the onset of Arabia-Eurasia collision-related deformation in northern Iran. Two stratigraphic intervals, informally named the Gand Ab and Narijan units, represent a former basin system that existed in the Alborz. The Gand Ab unit is composed of marine lagoonal mudstones, fluvial and alluvial-fan clastic rocks, fossiliferous Rupelian to Burdigalian marine carbonates, and basalt flows yielding ^...

  8. An investigation of the genus Mesacanthus (Chordata: Acanthodii) from the Orcadian Basin and Midland Valley areas of Northern and Central Scotland using traditional morphometrics

    Baron, Matthew G.


    Mesacanthus is a common and speciose genus of acanthodian fish from Lower Old Red Sandstone and Middle Old Red Sandstone assemblages (representing the Lower Devonian and Middle Devonian respectively) and is well represented in many palaeoichthyology collections in the UK. Based upon descriptions given during the 19th century, specimens of the genus Mesacanthus from the Orcadian Basin and Midland Valley areas of Northern and Central Scotland have historically been referred to a number of diffe...

  9. Hydrogeochemistry of co-occurring geogenic arsenic, fluoride and iodine in groundwater at Datong Basin, northern China.

    Pi, Kunfu; Wang, Yanxin; Xie, Xianjun; Su, Chunli; Ma, Teng; Li, Junxia; Liu, Yaqing


    Abnormal levels of co-occurring arsenic (As), fluorine (F) and iodine (I) in groundwater at Datong Basin, northern China are geochemically unique. Hydrochemical, (18)O and (2)H characteristics of groundwater were analyzed to elucidate their mobilization processes. Aqueous As, F and I ranged from 5.6 to 2680 μg/L, 0.40 to 3.32 mg/L and 10.1 to 186 μg/L, respectively. High As, F and I groundwater was characterized by moderately alkaline, high HCO3(-), Fe(II), HS(-) and DOC concentrations with H3AsO3, F(-) and I(-) as the dominant species. The plots of δ(18)O values and Cl/Br ratios versus Cl(-) concentration demonstrate build-up of more oxidizing conditions and precipitation of carbonate minerals induced by vertical recharge and intensive evaporation facilitate As retention to Fe (hydr) oxides, but enhance F and I mobilization from host minerals. Under reducing conditions, As and I can be simultaneously released via reductive dissolution of Fe (hydr) oxides and reduction of As(V) and I(V) while F migration may be retarded due to effects of dissolution-precipitation equilibria between carbonate minerals and fluorite. With the prevalence of sulfate-reducing condition and lowering of HCO3(-) concentration, As and I may be sequestered by Fe(II) sulfides and F is retained to fluorite and on clay mineral surfaces. PMID:26282220

  10. Simulation experiment on hydrocarbon generating potential of various source rocks on the northern margin of the Qaidam Basin, Qinghai, China

    LI Xin; WANG Dongliang; LIU Baoquan; REN Chunling; GUO Jianying; SU Xuefeng; WANG Jian


    The northern margin of the Qaidam Basin is one of the main oil-gas exploration areas in western China, where source rocks are composed mostly of Middle and Lower Jurassic dark mud shale, carbargillite and coal. A large number of subsurface and outcrop samples differing in lithology with different types of organic matter were selected for resource evaluation, research and calculation. And among them, 13 samples were used for simulation experiment on hydrocarbon generating potential of various source rocks. At first, two kinds of heating modes were compared through simulation experiment, including single temperature-step heating and continual heating. Perhaps, the process of hydrocarbon generation and expulsion occurred naturally between a close system and an open system. In addition, the first heating mode was convenient, and all its reaction products were involved in the whole thermal evolution, and the final simulation experimental results were basically in consistency with the natural evolution trend. Therefore, the first heating mode was adopted and the hydrocarbon yield of every sample was worked out. According to the type and lithology of organic matter and the hydrocarbon yield of samples for simulation experiment, hydrocarbon generation and expulsion mode with three kinds of lithology and five types of source rock has been established to provide the basis for hydrocarbon generation evaluation, research and resource calculation.

  11. Quantification and multivariate analysis of water erosion in the Mediterranean region. A case study of the Isser basin. northern Algeria

    Zeggane, Houari; Boutoutaou, Djamel


    In the Mediterranean region, the specifisity of erosion stems from a particularly contrasted climate, drought, and from summer and autumn severe thunderstorms. The process of erosion generates substantial loss of soil and affects any kind of crop. The adopted approach aims to establish regression models in order to highlight the relationship between solid and liquid flows at four measurement stations in the Isser catchement area, northern Ageria. The Power Model seems to explain this relationship. The quantification and temporal analysis of solid matter transport showed that the rates of erosion are high along the study area. The annual mean solid matter transport for the whole basin is about 2 200 t/km2.year, of which the main part is recorded in autumn during peak flows. The different factors involved in the process of water erosion are determined in advance in order to establish a model between the predictand variable, which is the specific erosion, and other predictors. Besides, a functional relationship has been highlighted between water erosion and the mean slope, the drainage density and the lithology index.

  12. Seismicity in the Raton Basin of Southern Colorado and Northern New Mexico, USA, as Recorded by a Local Array

    Macartney, H.


    Microseismic events (Basin of southern Colorado and northern New Mexico, USA, over a period of 18 months following the occurrence of a 5.3 magnitude event near Trinidad CO in August, 2011. Micro-seismicity was observed in the region, concentrated in six clusters at depths of 6-12 km below the surface, deep in the basement, and 4-10 km below zones used for fluid disposal from an overlying coalbed methane natural gas field. Clusters are separated from disposal zones by large aseismic intervals. The clusters are mixed in character; both planar and elongate amorphous swarms, some continually active and some as short-lived bursts, with larger initial events tending to occur deeper and smaller after-shocks propagating upward and away from the nucleating events. Magnitudes range between 0 and 3, with the vast majority being less than 1.5M. Most of the clusters have no disposal wells above and no seismic activity was correlated with changes in fluid disposal. No seismicity was detected from hydraulic fracturing operations.

  13. Stable isotope record of Eemian seasonal temperature from MIS 5e tufa stromatolite; Somme Basin, Northern France

    J. Dabkowski


    Full Text Available In many modern to sub-fossil deposits tufa formations, very well crystallised deposits called stromatolites are preserved. These are often strongly laminated deposits, the laminae linked to seasonal climatic and environmental variations. Where found in fossil tufas such deposits have huge potential as high resolution archives of Pleistocene climate. One of the first investigations of this type has been performed on a 2.5 cm-radius stromatolite from the Eemian sequence of Caours (Somme Basin, Northern France, where precise observations in thin section have been combined with intra-lamina δ18O and δ13C analyses. Independent interpretations of petrographical and geochemical data are strongly coherent and demonstrate a clear seasonal signal. Moreover, as δ18O is temperature dependent, we have quantified likely maximum water temperature variations between summer and winter at Caours. A small mismatch between the δ18O derived temperature values and the typical modern range is observed, which may reflect a real difference between modern and Eemian temperature seasonality. This study supports previous investigations performed on a laminated tufa from central Greece and clearly confirms the potential of tufa stromatolites as records of seasonal climatic information and for the quantification of riverine water temperature variations.

  14. Thick-skinned Contractional Salt Structures in the Kuqa Depression, the Northern Tarim Basin: Constraints from Physical Experiments

    YU Yixin; TANG Liangjie; YANG Wenjing; JIN Wenzheng; PENG Gengxin; LEI Ganglin


    Thick-skinned contractional salt structures are widely developed in the western Kuqa depression, northern Tarim basin. To understand the mechanisms that govern the development of these structures, physical experiments are conducted and the results show that they are largely governed by the activities of basement faults and the forming of paleo-uplifts and basement slopes. The model materials in this study are dry sand, vaseline and plasticene (or hard foam), simulating the suprasalt, salt, and subsalt layers respectively. The experiments show that, due to the activities of basement faults and the forming of the paleo-uplifts, salt bodies usually accumulate and thicken significantly on the middle top of the paleo-uplifts which are constrained by the pre-exiting boundary faults. The development of large-scale thrust faults and salt nappes is favored by the basement slops with larger dips. The experiments also conclude that differential structural deformation could occur between the subsalt and suprasalt layers because of the presence of salt layers. Their geometries and the locations of structural highs are different, despite of the great similarities in the uplifted areas. The pierced salt diapir is not observed in the experiments, which indicates that the contractional shortening does not effectively accelerate the development of the salt diapir.

  15. Structural framework and its evolution in Chasang area of Qiangtang Basin in northern Tibetan

    刘池洋; 杨兴科; 任战利; 赖绍聪; 陈刚; 赵红格; 魏永佩; 郑孟林; 王成善


    Through comprehensive research on the various geophysical and geological data acquired recently, we consider that the Chasang area in the western uplift of Qiangtang is a huge south-dipping block which is overlapped by several east-west trending blocks rather than a simple and palaeo-doming existing for a long time. The structural and geophysical features of the area, which only alone limited between Shuanghu and Rongma districts, are of no regional significance. Their development is closely related with the approximately south-north trending transform faults developed during the Mesozoic era on the east and west sides of the area and their later continuous movement. The compressing, overlapping and uplifting of the Chasang area began at the stage of reversing of the Qiangtang Basin during the Lower Cretaceous, which is in direct relation with Bangonghu-Dingqing limited ocean’s closure and the convergence of the neighboring blocks. The compression and overlapping of the area have further developed and re

  16. 26Al/10Be burial dating of Xujiayao-Houjiayao site in Nihewan Basin, northern China.

    Hua Tu

    Full Text Available The Xujiayao-Houjiayao site in Nihewan Basin is among the most important Paleolithic sites in China for having provided a rich collection of hominin and mammalian fossils and lithic artifacts. Based on biostratigraphical correlation and exploratory results from a variety of dating methods, the site has been widely accepted as early Upper Pleistocene in time. However, more recent paleomagnetic analyses assigned a much older age of ∼500 ka (thousand years. This paper reports the application of 26Al/10Be burial dating as an independent check. Two quartz samples from a lower cultural horizon give a weighted mean age of 0.24 ± 0.05 Ma (million years, 1σ. The site is thus younger than 340 ka at 95% confidence, which is at variance with the previous paleomagnetic results. On the other hand, our result suggests an age of older than 140 ka for the site's lower cultural deposits, which is consistent with recent post-infrared infrared stimulated luminescence (pIR-IRSL dating at 160-220 ka.

  17. Late Quaternary evolution of the Rotoaira Basin, northern Tongariro ring plain, New Zealand

    The last 100,000 yr record of volcaniclastic sedimentation in the Rotoaira Basin reflects the critical role played by tectonic and eruptive activity that led to: (1) the catastrophic emplacement of Te Whaiau Formation (60-55 ka); (2) major episodes of effusive activity (c. 30 ka and c. 15 ka); and (3) syn- and post-eruptive lahar aggradation on the shores of Lake Rotoaira. Stratigraphic unconformities, fluvial and aeolian reworking, and subsequent volcanogenic sedimentation indicate that climate change driven periods of erosion contributed significantly to the evolution of the landscape during the late Quaternary. Waters that accumulated in a newly expanded graben formed Lake Rotoaira. An attempt to core through the sediments on the lake's floor revealed a >6.5 m thick mantling of Taupo ignimbrite, restricting chronostratigraphic sampling to the last 1.85 ka. Lake Rotoaira pollen profiles record: (1) the destruction of the indigenous forest by the Taupo ignimbrite eruption; (2) the following period of vegetation recovery (c. 300 yr); and (3) periods of human occupation of the lakeshores (bracken spores and Pinus pollen) in the younger sediments. Coarse sand generated by the 1995-96 tephra-producing Ruapehu eruptions also contributed to the recent lake sedimentation. (author). 59 refs., 9 figs., 1 tab

  18. Mesozoic deformation in the Chaoshan Depression of the Pearl River Mouth Basin, northern South China Sea

    Zhang, Jiangyang; Sun, Zhen; Zhang, Yunfan; Li, Fucheng


    Newly collected, high resolution multi-beam sonar data are combined with previous bathymetry data to produce an improved bathymetric map of Shatsky Rise oceanic plateau. Bathymetry data show that two massifs within Shatsky Rise are immense central volcanoes with gentle flank slopes declining from a central summit. Tamu Massif is a slightly elongated, dome-like volcanic edifice; Ori Massif is square shaped and smaller in area. Several down-to-basin normal faults are observed on the western flank of the massifs but they do not parallel the magnetic lineations, indicating that these faults are probably not related to spreading ridge faulting. Moreover, the faults are observed only on one side of the massifs, which is contrary to expectations from a mechanism of differential subsidence around the massif center. Multi-beam data show many small secondary cones with different shapes and sizes that are widely-distributed on Shatsky Rise massifs, which imply small late-stage magma sources scattered across the surface of the volcanoes in the form of lava flows or explosive volcanism. Erosional channels occur on the flanks of Shatsky Rise volcanoes due to mass wasting and display evidence of down-slope sediment movement. These channels are likely formed by sediments spalling off the edges of summit sediment cap.

  19. Genetic Relationship between Natural Gas Dispersal Zone and Uranium Accumulation in the Northern Ordos Basin, China

    GAN Huajun; XIAO Xianming; LU Yongchao; JIN Yongbin; TIAN Hui; LIU Dehan


    The Ordos Basin is well-known for the coexistence of oil, natural gas, coal and uranium. However, there has been little research to discuss the genetic relationship between them. In this paper, a case study of the Zaohuohao area in Dongsheng, Inner Mongolia, China, is conducted to investigate the genetic relationship between the natural gas and the uranium accumulation. Fluid inclusion data from the uranium-bearing sandstone samples indicate that the fluid inclusions formed in a gas-water transition zone. Using the homogeneous temperatures of aqueous inclusions coeval with hydrocarbonbearing inclusions, combined with the buried history and paleo-temperature data, the gas-water transition zone reached the area at about 110 Ma. On the basis of this, the contents of Uranium (U)and Total Organic Carbon (TOC) of the samples were analyzed, and there was no obvious relation between them. With regard to the available data from both publications and this study, it is found that the U mineralization has a spatiotemporal accordance with the gas-water dispersal zone. Thus, it is believed that the natural gas in the gas-water zone is an effective reducer to the U-bearing ground water abundant in oxygen, which is the main factor to U accumulation. This result can be used as the reference to the U mines predicting and prospecting.

  20. Winter and spring mixing depths affect the trophic status and composition of phytoplankton in the northern meromictic basin of Lake Lugano

    Marco SIMONA


    Full Text Available The trophic state of Lake Lugano is still too high to be acceptable, despite extensive recovery measures undertaken in recent decades which have resulted in a reduction of the external phosphorus load to the deepest of the lake's basins (northern basin; Zmax=286 m to fairly acceptable values. Since meromixis was established in the middle of last century, the deep hypolimnion of the northern basin (the layer between ca 100 m and the bottom has contained high quantities of nutrients (especially phosphorus which are a major potential source of internal load. When there are particularly strong winter mixing events, a portion of this phosphorus reserve is redistributed along the upper water column (0-100 m. The impact of meteo-climatic conditions on the plankton biocenosis were analysed using data collected in the northern basin (Gandria station during the three-year period 1998-2000. The phytoplankton composition, which is typical of eutrophicated waters, shows marked interannual variations, also depending on the degree of mixing of the waters at the start of the vegetative period. Though there is no steady pattern of typical dominant species / master species in the lake, there is a seasonal succession characterised by a marked development of diatoms in spring, and a predominance of chlorophyceans and cyanobacteria in summer and autumn. Under present conditions, the mechanisms of internal replenishment of nutrients towards the euphotic layer, due to the phenomena of late winter and spring mixing, constitute a significant source of nutrients for the spring and summer growth of phytoplankton. On the other hand, pronounced mixing phenomena, like those occurring in the two-year period 1999-2000, can reduce the hypolimnetic nutrient reserves and cause a decrease in the trophic potential of the basin, contrasting with an increase in algal biomass in the euphotic zone.

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

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


    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.

  2. Preliminary Paleomagnetic Results From Tertiary Rocks of Sedimentary Basins in Northern Vietnam and Tectonic Implications

    Zhao, X.; Liu, Z.; Le, K.; Zhao, Y.; Hoang, V.; Phan, D.


    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.

  3. Understanding the Hydrogeology of Raya Valley Basin, Northern Ethopia Using Stablee Isotopes of Water

    The Raya valley is located in the northern part of Ethiopia. The study area is connected to the Ethiopian rift system and bounded by the Ethiopian plateau to the west and Cherecher Mountain to the east. The study area is characterized by its semiarid climate. In order to investigate isotopic characteristics of different water bodies and groundwater recharge, water samples were collected in the summer rainy season and analysed for stable isotopes of oxygen and hydrogen by a laser based liquid water isotope analyser. Most of the groundwater samples are plotted just below the LMWL, which indicates that the origin is meteoric water and affected by secondary evaporation. There are highly depleted water samples in the eastern side of the study area, which could be attributed to the existence of palaeowater. Groundwater is mainly recharged by rain water and intermittent rivers. Open water bodies (the lake Ashenge and Gerjale swamp area) show enrichment due to high rate of evaporation. Isotopically the flood water in the highland aarea is depleted as a result of high rate of rainfall, high humidity and low rate of evaporation. (author)

  4. Structural architecture and tectonic evolution of the Maghara inverted basin, Northern Sinai, Egypt

    Moustafa, Adel R.


    Large NE-SW oriented asymmetric inversion anticlines bounded on their southeastern sides by reverse faults affect the exposed Mesozoic and Cenozoic sedimentary rocks of the Maghara area (northern Sinai). Seismic data indicate an earlier Jurassic rifting phase and surface structures indicate Late Cretaceous-Early Tertiary inversion phase. The geometry of the early extensional fault system clearly affected the sense of slip of the inverted faults and the geometry of the inversion anticlines. Rift-parallel fault segments were reactivated by reverse slip whereas rift-oblique fault segments were reactivated as oblique-slip faults or lateral/oblique ramps. New syn-inversion faults include two short conjugate strike-slip sets dissecting the forelimbs of inversion anticlines and the inverted faults as well as a set of transverse normal faults dissecting the backlimbs. Small anticline-syncline fold pairs ornamenting the steep flanks of the inversion anticlines are located at the transfer zones between en echelon segments of the inverted faults.

  5. Characterization of submarine canyon bathymetries in northern Ionian Sea, Italy, using sediment geochemical variation induced by transportation distance and basin depth

    Francesco, Perri; Tohru, Ohta; Salvatore, Critelli


    Geochemical data of marine mud sediments collected from the Esaro, Neto and Corigliano canyons in the northern Ionian Sea (southern Italy) were investigated in order to characterize canyon bathymetry types. Mud sample compositions analyzed by the principal component analysis (PCA) provided useful information for the morphology of the depositional area of the northern Ionian Sea. The use of sediment geochemical data as well as transportation distance and depth as input variables for PCA enabled the extraction of following latent variables: basin depth (PC1), sedimentation rate (PC2) and transportation distance (PC3). Based on these results, we further developed geochemical indices that can estimate basin depth (F1), sedimentation rate (F2) and transportation distance (F3); these functions can be solely calculated from the elemental concentration data of the mud samples. Since these F1, F2 and F3 functions are mathematically independent variables, they facilitate more precise characterization of individual canyon types. That is, the Esaro Canyon is regarded as a sediment-starved deep canyon characterized by a single source area; the Neto Canyon can be seen as a deeply sloped submarine apron system and sediments are mainly supplied by the sediment gravity flows; the Corigliano Canyon is characterized by multiple sources and moderately sloped system, whose sediments disperse mainly by traction currents. These interpretations are concordant with the basin bathymetry of the studied area. Therefore, F1, F2 and F3 functions might be applicable to any oceanic basins.

  6. Assessment of River Habitat Quality in the Hai River Basin, Northern China

    Yuekui Ding


    Full Text Available We applied a river habitat quality (RHQ assessment method to the Hai River Basin (HRB; an important economic centre in China; to obtain baseline information for water quality improvement; river rehabilitation; and watershed management. The results of the assessment showed that the river habitat in the HRB is seriously degraded. Specifically; 42.41% of the sites; accounting for a river length of 3.31 × 104 km; were designated poor and bad. Habitat in the plain areas is seriously deteriorated; and nearly 50% of the sites; accounting for a river length of 1.65 × 104 km; had either poor or bad habitats. River habitat degradation was attributable to the limited width of the riparian zone (≤5 m; lower coverage of riparian vegetation (≤40%; artificial land use patterns (public and industrial land; frequent occurrence of farming on the river banks and high volumes of solid waste (nearly 10 m3; single flow channels; and rare aquatic plants (≤1 category. At the regional scale; intensive artificial land use types caused by urbanization had a significant impact on the RHQ in the HRB. RHQ was significantly and negatively correlated with farmland (r = 1.000; p < 0.01 and urban land (r = 0.998; p < 0.05; and was significantly and positively correlated with grassland and woodland (r = 1.000; p < 0.01. Intensive artificial land use; created through urbanization processes; has led to a loss of the riparian zone and its native vegetation; and has disrupted the lateral connectivity of the rivers. The degradation of the already essentially black rivers is exacerbated by poor longitudinal connectivity (index of connectivity is 2.08–16.56; caused by reservoirs and sluices. For river habitat rehabilitation to be successful; land use patterns need to be changed and reservoirs and sluices will have to be regulated.

  7. Assessment of River Habitat Quality in the Hai River Basin, Northern China.

    Ding, Yuekui; Shan, Baoqing; Zhao, Yu


    We applied a river habitat quality (RHQ) assessment method to the Hai River Basin (HRB); an important economic centre in China; to obtain baseline information for water quality improvement; river rehabilitation; and watershed management. The results of the assessment showed that the river habitat in the HRB is seriously degraded. Specifically; 42.41% of the sites; accounting for a river length of 3.31 × 10⁴ km; were designated poor and bad. Habitat in the plain areas is seriously deteriorated; and nearly 50% of the sites; accounting for a river length of 1.65 × 10⁴ km; had either poor or bad habitats. River habitat degradation was attributable to the limited width of the riparian zone (≤5 m); lower coverage of riparian vegetation (≤40%); artificial land use patterns (public and industrial land); frequent occurrence of farming on the river banks and high volumes of solid waste (nearly 10 m³); single flow channels; and rare aquatic plants (≤1 category). At the regional scale; intensive artificial land use types caused by urbanization had a significant impact on the RHQ in the HRB. RHQ was significantly and negatively correlated with farmland (r = 1.000; p urban land (r = 0.998; p urbanization processes; has led to a loss of the riparian zone and its native vegetation; and has disrupted the lateral connectivity of the rivers. The degradation of the already essentially black rivers is exacerbated by poor longitudinal connectivity (index of connectivity is 2.08-16.56); caused by reservoirs and sluices. For river habitat rehabilitation to be successful; land use patterns need to be changed and reservoirs and sluices will have to be regulated. PMID:26393628

  8. Subsurface structure and stratigraphy of the northwest end of the Turkana Basin, Northern Kenya Rift, as revealed by magnetotellurics and gravity joint inversion

    Abdelfettah, Yassine; Tiercelin, Jean-Jacques; Tarits, Pascal; Hautot, Sophie; Maia, Marcia; Thuo, Peter


    In order to understand the subsurface stratigraphy and structure of the northwest end of the Turkana Basin, Northern Kenya Rift, we used 2-D joint inversion of magnetotelluric (MT) and gravity data acquired along 3 profiles perpendicular to the main Murua Rith-Lapur Rift Border Fault. The regional geology is characterized by a basement of Precambrian age overlain by a ≤500-m thick sandstone formation named the Lapur Sandstone of upper Cretaceous-lower Eocene in age, covered by thick rhyolitic and basaltic lavas of late Eocene-middle Miocene age, known as the "Turkana Volcanics". Final interpretation of the resistivity and density models, until 5 km depth, obtained by the joint inversion approach confirms the previous general knowledge about the half-graben geometry of the northern part of the Turkana Basin. The main Murua Rith-Lapur Rift Border Fault is well identified by both gravity and MT. At least, two other important secondary faults without surface expression are also identified. A new small half-graben basin, named the Kachoda Basin, parallel to the main Turkana Basin and filled by 1.5 km of sediments, has been also characterized. This study also highlights strong thickness variations of the three main geological units that could be expected in the subsurface of the Turkana Basin. For example, the sedimentary Nachukui and Kibish Formations reach up to >3 km in thickness at the eastern end of the north and central profiles. Lateral variations of the topography of the Precambrian basement are also evidenced. Conceptual geological models, which result from the combination of the obtained density and resistivity models as well as from geological and reflection seismic data, are proposed. In such an area of intensive and promising oil exploration, these models are essential in terms of identification of reservoirs, source rocks and trapping mechanisms.

  9. Aerosol chemistry above an extended Archipelago of the Eastern Mediterranean basin during strong northern winds

    E. Athanasopoulou


    Full Text Available Detailed aerosol chemical predictions by a carefully designed model system (i.e. PMCAMx, WRF, GEOS-CHEM, along with airborne and ground-based observations, are presented and analyzed over a wide domain covering the Aegean Archipelago. The studied period is ten successive days during the summer of 2011, characterized by the most frequent prevailing wind conditions (Etesian regime. The submicron aerosol load in the lower troposphere above the Archipelago (< 2.2 km altitude is homogenously enriched in sulfate (average modeled and measured submicron sulfate of 5.5 and 5.8 μg m−3, respectively, followed by organics (2.3 and 4.4 μg m−3 and ammonium (1.5 and 1.7 μg m−3. Aerosol concentrations smoothly decline aloft, reaching lower values (< 1 μg m−3 above 4.2 km altitude. Model performance is found good (according the selected evaluation criteria for sulfate, ammonium, chloride, elemental carbon, organic carbon and total PM10 mass concentration, indicating a satisfactory representation of the aerosol chemistry and precursors. Higher model discrepancies are confined to the highest (e.g. peak sulfate values and lowest ends (e.g. nitrate of the airborne aerosol mass size distribution, as well as in airborne organic concentrations (model underestimation around 50%. The latter is most probably related to the intense fire activity upwind the Archipelago (i.e. Balkan area and Black Sea coastline, which is not represented in the current model application. Overall, the model system shows the best agreement with observations under strong northeastern winds over the Archipelago and up to 2.2 km altitude. The activation of the chemical ageing of biogenic particles is suggested to be used for the aerosol chemistry module, when treating organics in a sufficient nitrogen and sulfate-rich environment, such as that over the Aegean basin. More than 70% of the predicted aerosol mass over the Aegean Archipelago during a representative Etesian episode is


    Blount, G.; Millings, M.


    A reconnaissance assessment of the carbon dioxide (CO{sub 2}) sequestration potential within the Triassic age rift trend sediments of South Carolina, Georgia and the northern Florida Rift trend was performed for the Office of Fossil Energy, National Energy Technology Laboratory (NETL). This rift trend also extends into eastern Alabama, and has been termed the South Georgia Rift by previous authors, but is termed the South Carolina, Georgia, northern Florida, and eastern Alabama Rift (SGFAR) trend in this report to better describe the extent of the trend. The objectives of the study were to: (1) integrate all pertinent geologic information (literature reviews, drilling logs, seismic data, etc.) to create an understanding of the structural aspects of the basin trend (basin trend location and configuration, and the thickness of the sedimentary rock fill), (2) estimate the rough CO{sub 2} storage capacity (using conservative inputs), and (3) assess the general viability of the basins as sites of large-scale CO{sub 2} sequestration (determine if additional studies are appropriate). The CO{sub 2} estimates for the trend include South Carolina, Georgia, and northern Florida only. The study determined that the basins within the SGFAR trend have sufficient sedimentary fill to have a large potential storage capacity for CO{sub 2}. The deeper basins appear to have sedimentary fill of over 15,000 feet. Much of this fill is likely to be alluvial and fluvial sedimentary rock with higher porosity and permeability. This report estimates an order of magnitude potential capacity of approximately 137 billion metric tons for supercritical CO{sub 2}. The pore space within the basins represent hundreds of years of potential storage for supercritical CO{sub 2} and CO{sub 2} stored in aqueous form. There are many sources of CO{sub 2} within the region that could use the trend for geologic storage. Thirty one coal fired power plants are located within 100 miles of the deepest portions of

  11. Structure and Stratigraphy of the Rift Basins in the Northern Gulf of California: Results from Analysis of Seismic Reflection and Borehole Data.

    Martín, A.; González, M.; Helenes, J.; García, J.; Aragón, M.; Carreño, A.


    The northern Gulf of California contains two parallel, north-south trending rift basin systems separated by a basement-high. The interpretation of several exploration wells, and ~4500 km of seismic reflection data from PEMEX (Mexican national oil company) indicate that the tectonically active basins to the west (Wagner- Consag and Upper Delfin basins) may have initiated synchronously with the now abandoned Tiburón- Tepoca-Altar basins to the east in the Sonora margin. In both basin systems the lower sequence (A) is marine mudstone-siltstone, has parallel reflectors and a largely uniform thickness that reaches up to1.5 km, and gradually pinches out toward the lateral margins. This suggests that the unit was deposited prior to their segmentation by transtensional faulting. Marine microfossils from borehole samples from sequence A in the Tiburón and Consag basins indicates middle Miocene (>11.2 Ma) proto-Gulf conditions. Sequence B conformably overlies sequence A, and is characterized by up to 2 km growth strata with a fanning geometry that show a clear genetic relationship to the major transtensional faults that control the segmentation of the two basin systems. Sequence C in the Tiburón and Tepoca basins is comparatively thin (<800 m) and includes several unconformities, but is much less affected by faulting. In contrast, sequence C in the active Wagner, Consag and Upper Delfin basin is a much thicker (up to 2 km) growth sequence with abundant volcanic intrusions. Marked variations in sequence C in the different basin systems clearly demonstrate a major westward shift of deformation and subsidence at this time. The modern depocenter in Wagner-Consag basins is controlled by the Consag and Wagner faults, which trend parallel to the north ~20 km apart, and show opposite normal offset. These two faults merge at an oblique angle (70°-50°, respectively) into the Cerro Prieto transform fault to the north and likely accommodate an important amount of dextral shear. To

  12. Geo-economy of the Caspian basin

    The Caspian area is essential for the development of the central Asia countries and Caucasus. Excepted the Iran and the Russia, these areas economy is poor. The hydrocarbons exploitation should reinforce the economic weight of these States. The author analyzes the Caspian area economies and shows that the basin economies are confronted with three handicaps, and that even with different economic ways, the soviet economic system is still present in the basin. (A.L.B.)

  13. Determining the source and genetic fingerprint of natural gases using noble gas geochemistry: a northern Appalachian Basin case study

    Hunt, Andrew G.; Darrah, Thomas H.; Poreda, Robert J.


    Silurian and Devonian natural gas reservoirs present within New York state represent an example of unconventional gas accumulations within the northern Appalachian Basin. These unconventional energy resources, previously thought to be noneconomically viable, have come into play following advances in drilling (i.e., horizontal drilling) and extraction (i.e., hydraulic fracturing) capabilities. Therefore, efforts to understand these and other domestic and global natural gas reserves have recently increased. The suspicion of fugitive mass migration issues within current Appalachian production fields has catalyzed the need to develop a greater understanding of the genetic grouping (source) and migrational history of natural gases in this area. We introduce new noble gas data in the context of published hydrocarbon carbon (C1,C2+) (13C) data to explore the genesis of thermogenic gases in the Appalachian Basin. This study includes natural gases from two distinct genetic groups: group 1, Upper Devonian (Marcellus shale and Canadaway Group) gases generated in situ, characterized by early mature (13C[C1  C2][13C113C2]: –9), isotopically light methane, with low (4He) (average, 1  103 cc/cc) elevated 4He/40Ar and 21Ne/40Ar (where the asterisk denotes excess radiogenic or nucleogenic production beyond the atmospheric ratio), and a variable, atmospherically (air-saturated–water) derived noble gas component; and group 2, a migratory natural gas that emanated from Lower Ordovician source rocks (i.e., most likely, Middle Ordovician Trenton or Black River group) that is currently hosted primarily in Lower Silurian sands (i.e., Medina or Clinton group) characterized by isotopically heavy, mature methane (13C[C1 – C2] [13C113C2]: 3), with high (4He) (average, 1.85  103 cc/cc) 4He/40Ar and 21Ne/40Ar near crustal production levels and elevated crustal noble gas content (enriched 4He,21Ne, 40Ar). Because the release of each crustal noble gas (i.e., He, Ne, Ar

  14. Growth Normal Faulting at the Western Edge of the Metropolitan Taipei Basin since the Last Glacial Maximum, Northern Taiwan

    Chih-Tung Chen


    Full Text Available Growth strata analysis is an useful tool in understanding kinematics and the evolution of active faults as well as the close relationship between sedimentation and tectonics. Here we present the Shanchiao Fault as a case study which is an active normal fault responsible for the formation of the 700-m-thick late Quaternary deposits in Taipei Basin at the northern tip of the Taiwan mountain belt. We compiled a sedimentary record, particularly the depositional facies and their dated ages, at three boreholes (SCF-1, SCF-2 and WK-1, from west to east along the Wuku Profile that traverses the Shanchiao Fault at its central segment. By incorporating the global sea level change curve, we find that thickness changes of sediments and changes of depositional environments in the Wuku area are in a good agreement with a rapid sea level rise since the Last Glacial Maximum (LGM of about 23 ka. Combining depositional facies changes and their ages with their thickness, we are able to introduce a simple back-stripping method to reconstruct the evolution of growing strata across the Shanchiao Fault since the LGM. We then estimate the vertical tectonic slip rate since 23 ka, which exhibits 2.2 mm yr-1 between SCF-2 and WK-1 and 1.1 mm yr-1 between SCF-1 and SCF-2. We also obtain the Holocene tectonic subsidence rate of 2.3 mm yr-1 at WK-1 and 0.9 mm yr-1 at SCF-2 since 8.4 ka. We thus conclude that the fault zone consists of a high-angle main fault to the east between SCF-2 and WK-1 and a western lower-angle branch fault between SCF-1 and SCF-2, resembling a tulip structure developed under sinistral transtensional tectonism. We find that a short period of 600-yr time span in 9 - 8.4 ka shows important tectonic subsidence of 7.4 and 3.3 m for the main and branch fault, respectively, consistent with possible earthquake events proposed by previous studies during that time. A correlation between geomorphology and subsurface geology in the Shanchiao Fault zone shows

  15. Identifying hydro-meteorological events from precipitation extremes indices and other sources over northern Namibia, Cuvelai Basin

    Frans C. Persendt


    Full Text Available Worldwide, more than 40% of all natural hazards and about half of all deaths are the result of flood disasters. In northern Namibia flood disasters have increased dramatically over the past half-century, along with associated economic losses and fatalities. There is a growing concern to identify these extreme precipitation events that result in many hydro-meteorological disasters. This study presents an up to date and broad analysis of the trends of hydrometeorological events using extreme daily precipitation indices, daily precipitation data from the Grootfontein rainfall station (1917–present, regionally averaged climatologies from the gauged gridded Climate Research Unit (CRU product, archived disasters by global disaster databases, published disaster events in literature as well as events listed by Mendelsohn, Jarvis and Robertson (2013 for the data-sparse Cuvelai river basin (CRB. The listed events that have many missing data gaps were used to reference and validate results obtained from other sources in this study. A suite of ten climate change extreme precipitation indices derived from daily precipitation data (Grootfontein rainfall station, were calculated and analysed. The results in this study highlighted years that had major hydro-meteorological events during periods where no data are available. Furthermore, the results underlined decrease in both the annual precipitation as well as the annual total wet days of precipitation, whilst it found increases in the longest annual dry spell indicating more extreme dry seasons. These findings can help to improve flood risk management policies by providing timely information on historic hydro-meteorological hazard events that are essential for early warning and forecasting.

  16. Meltwater palaeohydrology of the Baker River basin (Chile/Argentina) during Late Pleistocene deglaciation of the Northern Patagonia Icefield

    Thorndycraft, Varyl; Bendle, Jacob; Benito, Gerardo; Sancho, Carlos; Palmer, Adrian; Rodríguez, Xavier


    The Late Pleistocene deglaciation of the Northern Patagonia Icefield (NPI) was characterised by rapid ice sheet thinning and retreat, and the development of large proglacial lake systems characterised by continental scale drainage reversals. In this region, research has focused primarily on the identification of former ice-limits (e.g. moraine ridges) for geochronological analyses, with little attention given to the meltwater palaeohydrology of major river valleys. The Baker River catchment drains the majority of the eastern ice shed of the NPI, with a basin area of 29,000 km2 that includes the large transboundary lakes of General Carrera/Buenos Aires and Cochrane/Puerreydón. The Baker River valley is aligned north to south, crossing the east-west valleys of the main NPI outflow glaciers, and thus represents an important aspect of regional Late Pleistocene palaeogeography. The Baker River valley therefore has the potential to refine regional models of deglaciation through better understanding of relationships between glacier dynamics, ice dammed lakes and meltwater pathways. Here we present geomorphological mapping from the Atlantic-Pacific drainage divide (over 150 km east of the Cordillera) to the lower Baker valley, in order to reconstruct Late Pleistocene palaeohydrology. We provide new mapping of palaeolake shoreline elevations and evidence for glacial lake outburst flood (GLOF) pathways that require a re-evaluation of the currently accepted palaeogeographic models. For example, the palaeohydrological evidence does not support existing models of a unified Buenos Aires/Puerreydón mega-lake at ca. 400m elevation. We propose a relative chronology of palaeohydrological events that help refine the published moraine chronology derived from cosmogenic nuclide exposure dating. Controls on Late Pleistocene meltwater palaeohydrology of the Baker catchment are discussed, including the interplay of glacial processes and regional tectonics, in particular, dynamic

  17. Scenarios for shale gas development and their related land use impacts in the Baltic Basin, Northern Poland

    Scenarios for potential shale gas development were modelled for the Baltic Basin in Northern Poland for the period 2015–2030 using the land allocation model EUCS100. The main aims were to assess the associated land use requirements, conflicts with existing land use, and the influence of legislation on the environmental impact. The factors involved in estimating the suitability for placement of shale gas well pads were analysed, as well as the potential land and water requirements to define 2 technology-based scenarios, representing the highest and lowest potential environmental impact. 2 different legislative frameworks (current and restrictive) were also assessed, to give 4 combined scenarios altogether. Land consumption and allocation patterns of well pads varied substantially according to the modelled scenario. Potential landscape fragmentation and conflicts with other land users depended mainly on development rate, well pad density, existing land-use patterns, and geology. Highly complex landscapes presented numerous barriers to drilling activities, restricting the potential development patterns. The land used for shale gas development could represent a significant percentage of overall land take within the shale play. The adoption of appropriate legislation, especially the protection of natural areas and water resources, is therefore essential to minimise the related environmental impact. -- Highlights: •A range of scenarios for shale gas development in Poland were modelled. •The impact in terms of land take and competition for land was assessed. •Of land used for industrial purposes, 7–12% was attributed to shale gas extraction. •If unregulated, 24% of well pads were developed within protected areas. •The legislative framework can have a major influence on overall environmental impact

  18. Natural resources and their prospects in the closed basins of rift valley marginal grabens in northern Ethiopia

    Meaza, Hailemariam; Frankl, Amaury; Poesen, Jean; Zenebe, Amanuel; Deckers, Jozef; Vaneetvelde, Veerle; Lanckriet, Sil; Nyssen, Jan


    With increasing population, producing more food and fibers has led to an expansion of the area under cultivation. For this, much attention is given to low-lying flat areas in search of suitable agricultural lands. The objectives of this paper are therefore: (1) to review the opportunities and challenges of natural resources in the marginal grabens for rural development; (2) to highlight the knowledge gaps and priorities in research and development in the marginal grabens, and (3) to supplement the literature review through repeat transect walks, focus group discussions and interviews across the western rift valley of northern Ethiopia. The paper shows that marginal grabens along the rift valleys are rich both in blue and green water resources due to their topographical and geological characteristics. Spate irrigation has been a growing water management practice to respond to soil moisture deficit. Besides, marginal grabens are fertile plains as a result of alluvial deposition that could be suitable for agricultural development. However, rainfall variability and groundwater withdrawal lead to graben basin closure and salinization. Notably, riverbed incisions and sediment deposition affects drainage systems and water supply in the marginal grabens. As a result, socioeconomic and natural capital of the marginal graben farmers are continuously threatened. Thus, the benefits of natural resources for rural development in the marginal grabens along the rift valley can be optimized if the current bottlenecks are converted into opportunities. A better understanding of the complex marginal graben system via a robust land evaluation framework will improve livelihoods of the communities that live in the (closed) marginal grabens. Keywords: population pressure, marginal grabens, endorheic lakes, salinization, Ethiopia

  19. Formation of hydrothermal deposits at Kings Triple Junction, northern Lau back-arc basin, SW Pacific: The geochemical perspectives

    Paropkari, Anil L.; Ray, Durbar; Balaram, V.; Surya Prakash, L.; Mirza, Imran H.; Satyanarayana, M.; Gnaneshwar Rao, T.; Kaisary, Sujata


    An inactive hydrothermal field was discovered near Kings Triple Junction (KTJ) in northern Lau back-arc basin during 19th cruise of R/V Akademik Mstislav Keldysh in 1990. The field consisted of a large elongated basal platform 'the pedestal' with several 'small' chimneys on its periphery and one 'main mound' superposed over it. The surrounding region is carpeted with lava pillows having ferromanganese 'precipitate' as infillings. The adjoining second field consisted of small chimney like growths termed as 'Christmas Tree' Field. The basal pedestal, the peripheral chimneys and small 'Christmas Tree' like growths (samples collected by MIR submersibles), though parts of the same hydrothermal field, differ significantly in their mineralogy and elemental composition indicating different history of formation. The pedestal slab consisting of chalcopyrite and pyrite as major minerals and rich in Cu is likely to have formed at higher temperatures than sphalerite dominated peripheral chimney. Extremely low concentration of high field strength elements (e.g. Zr, Hf, Nb and Ta) and enrichment of light REE in these sulfides indicate prominent influence of aqueous arc-magma, rich in subduction components. The oxide growths in the 'Christmas Tree' Field have two distinct layers, Fe rich orange-red basal part which seems to have formed at very low temperature as precipitates from diffused hydrothermal flows from the seafloor whereas Mn rich black surface coating is formed from hydrothermal fluids emanated from the seafloor during another episode of hydrothermal activity. Perhaps this is for the first time such unique hydrothermal oxide growths are being reported in association with hydrothermal system. Here, we discuss the possible processes responsible for the formation of these different hydrothermal deposits based on their mineralogy and geochemistry.

  20. Innovative Methodology for Detection of Fracture-Controlled Sweet Spots in the Northern Appalachian Basin

    Robert Jacobi; John Fountain; Stuart Loewenstein; Edward DeRidder; Bruce Hart


    For two consecutive years, 2004 and 2005, the largest natural gas well (in terms of gas flow/day) drilled onshore USA targeted the Ordovician Trenton/Black River (T/BR) play in the Appalachian Basin of New York State (NYS). Yet, little data were available concerning the characteristics of the play, or how to recognize and track T/BR prospects across the region. Traditional exploration techniques for entry into a hot play were of limited use here, since existing deep well logs and public domain seismic were almost non-existent. To help mitigate this problem, this research project was conceived with two objectives: (1) to demonstrate that integrative traditional and innovative techniques could be used as a cost-effective reconnaissance exploration methodology in this, and other, areas where existing data in targeted fracture-play horizons are almost non-existent, and (2) determine critical characteristics of the T/BR fields. The research region between Seneca and Cayuga lakes (in the Finger Lakes of NYS) is on strike and east of the discovery fields, and the southern boundary of the field area is about 8 km north of more recently discovered T/BR fields. Phase I, completed in 2004, consisted of integrating detailed outcrop fracture analyses with detailed soil gas analyses, lineaments, stratigraphy, seismic reflection data, well log data, and aeromagnetics. In the Seneca Lake region, Landsat lineaments (EarthSat, 1997) were coincident with fracture intensification domains (FIDs) and minor faults observed in outcrop and inferred from stratigraphy. Soil gas anomalies corresponded to ENE-trending lineaments and FIDs. N- and ENE-trending lineaments were parallel to aeromagnetic anomalies, whereas E-trending lineaments crossed aeromagnetic trends. 2-D seismic reflection data confirmed that the E-trending lineaments and FIDs occur where shallow level Alleghanian salt-cored thrust-faulted anticlines occur. In contrast, the ENE-trending FIDs and lineaments occur where Iapetan

  1. Innovative Methodology for Detection of Fracture-Controlled Sweet Spots in the Northern Appalachian Basin

    Robert Jacobi; John Fountain; Stuart Loewenstein; Edward DeRidder; Bruce Hart


    For two consecutive years, 2004 and 2005, the largest natural gas well (in terms of gas flow/day) drilled onshore USA targeted the Ordovician Trenton/Black River (T/BR) play in the Appalachian Basin of New York State (NYS). Yet, little data were available concerning the characteristics of the play, or how to recognize and track T/BR prospects across the region. Traditional exploration techniques for entry into a hot play were of limited use here, since existing deep well logs and public domain seismic were almost non-existent. To help mitigate this problem, this research project was conceived with two objectives: (1) to demonstrate that integrative traditional and innovative techniques could be used as a cost-effective reconnaissance exploration methodology in this, and other, areas where existing data in targeted fracture-play horizons are almost non-existent, and (2) determine critical characteristics of the T/BR fields. The research region between Seneca and Cayuga lakes (in the Finger Lakes of NYS) is on strike and east of the discovery fields, and the southern boundary of the field area is about 8 km north of more recently discovered T/BR fields. Phase I, completed in 2004, consisted of integrating detailed outcrop fracture analyses with detailed soil gas analyses, lineaments, stratigraphy, seismic reflection data, well log data, and aeromagnetics. In the Seneca Lake region, Landsat lineaments (EarthSat, 1997) were coincident with fracture intensification domains (FIDs) and minor faults observed in outcrop and inferred from stratigraphy. Soil gas anomalies corresponded to ENE-trending lineaments and FIDs. N- and ENE-trending lineaments were parallel to aeromagnetic anomalies, whereas E-trending lineaments crossed aeromagnetic trends. 2-D seismic reflection data confirmed that the E-trending lineaments and FIDs occur where shallow level Alleghanian salt-cored thrust-faulted anticlines occur. In contrast, the ENE-trending FIDs and lineaments occur where Iapetan

  2. Seismic hazard assessment for the Caucasus test area

    V. Trifonov


    Full Text Available The GSHAP CAUCAS test area was established under the INTAS Ct.94-1644 (Test Area for sismic Hazard Assessment in the Caucasus and NATO ARW Ct.95-1521 (Historical and Prehistorical Earthquakes in the Caucasus, with the initial support of IASPEI, UNESCO and ILP. The high tectonic interest and seismicity rate of the whole area, the availability of abundant multi-disciplinary data and the long established tradition in hazard assessment provide a unique opportunity to test different methodologies in a common test area and attempt to establish some consensus in the scientific community. Starting from the same input data (historical and instrumental seismic catalogue, lineament and homogeneous seismic source models six independent approaches to seismic hazard assessment have been used, ranging from pure historical deterministic to seismotectonic probabilistic and areal assessment methodologies. The results are here compared.

  3. Zircon Hf isotopic constraints on the mantle source of felsic magmatic rocks in the Phan Si Pan uplift and Tu Le basin, northern Vietnam

    Usuki, T.; Lan, C.; Tran, T.; Pham, T.; Wang, K.


    Permian plume-related rocks, such as picrites, flood basalts and silicic volcanic rocks occur in northern Vietnam. This area was displaced 600 km southeastward along the Ailao Shan-Red River fault during mid-Tertiary in response to the India-Eurasia collision. The original location of the area was situated at the central Emeishan Large Igneous Province (ELIP) in SW China before Tertiary. The picrites and flood basalts in northern Vietnam have been investigated by many authors and are comparable with the ELIP. While, felsic magmatisms in northern Vietnam has been poorly studied. Zircon U-Pb age and Hf isotopic data are useful to compare the felsic magmatism in northern Vietnam with that in the ELIP, because the magmatisms of the ELIP had a characteristic time period (260-250 Ma) and the Hf isotopes show a remarkable mantle signature. Therefore, this study carried out in-situ U-Pb ages and Hf isotopic compositions for 300 zircon grains in eighteen granitoids and rhyolites in Phan Si Pan uplift and Tu Le basin in northern Vietnam. Zircons from the granitoids and rhyolites occasionally show development of {101} pyramid and {100} prism crystal facies, suggesting typical zircons crystallized from high temperature alkaline granite. 206Pb/238U ages of granitoid and rhyolite yield consistently in a narrow range of 260 to 250 Ma, which coincides with those from peralkaline to metaluminous granites in the ELIP. ɛHf(t) values of zircons in rhyolites and granites of this study dominate in the range of +5 to +10, which is consistent with those from the ELIP. U-Pb ages and Hf isotopic compositions of zircons indicate that felsic magmatic rocks in the Phan Si Pan uplift and Tu La basin have been derived from the same mantle source with the ELIP.

  4. Eocene to late Oligocene history of crustal shortening within the Hoh Xil Basin and implications for the uplift history of the northern Tibetan Plateau

    Staisch, Lydia M.; Niemi, Nathan A.; Clark, Marin K.; Chang, Hong


    The timing and magnitude of deformation across the northern Tibetan Plateau are poorly constrained but feature prominently in geodynamic models of the plateau's evolution. The Fenghuoshan fold and thrust belt, located in the Hoh Xil Basin, provides a valuable record of the Cenozoic deformation history of the northern Tibetan Plateau. Here we integrate fault gouge geochronology, low-temperature thermochronology, geologic mapping, and a balanced cross section to resolve the deformation history of Hoh Xil Basin. Chronologic data suggest that deformation initiated in the mid-Eocene continued until at least 34 Ma and ceased by 27 Ma. The balanced cross section resolves 34 ± 12 km upper crustal shortening (24 ± 9%). We explore whether the observed Cenozoic shortening can account for the modern elevation and lithospheric thickness in the northern Tibetan Plateau. For a range of reasonable preshortening conditions, we conclude that the observed shortening alone cannot achieve modern crustal and mantle lithospheric thicknesses or modern elevation without either the removal of lithospheric mantle, the influx of lower crustal material, or some combination of these processes. Our results, along with previous studies, suggest that crustal shortening propagated into the northern Tibetan Plateau shortly after the onset of the Indo-Asian collision. The small magnitude of shortening and the late Oligocene cessation of deformation in the northern Tibetan Plateau raise questions of how and where the remaining Indo-Asian convergence was accommodated between Eocene to mid-Miocene time, prior to the approximately late Miocene establishment of the deformation patterns observed in the present day.

  5. Middle-Upper Ordovician (Darriwilian-Early Katian) Positive Carbon Isotope Excursions in the Northern Tarim Basin, Northwest China:Implications for Stratigraphic Correlation and Paleoclimate

    Cunge Liu; Guorong Li; Dawei Wang; Yongli Liu; Mingxia Luo; Xiaoming Shao


    ABSTRACT:Three positive carbon isotope excursions are reported from Middle–Upper Ordovician in Tahe oil-gas field, northern Tarim Basin. Based on conodont biostratigraphy, the Middle Darriwilian Isotope Carbon Excursion (MDICE) and the Guttenberg Carbon Isotope Excursion (GICE) are identified from Darriwilian to Early Katian by the aid of whole-rock carbon isotope data from two well cores. Positive excursion within conodont Pygodus anserinus zone is developed in Early Sandbian, and the fluctuation range is no less than MDICE. Because the range of this excursion in the generalized global carbon isotope curve is short, previous studies paid little attention to it, and named Early Sandbian Isotope Carbon Excursion (ESICE) in this paper. Furthermore, these positive excursions are not directly related to sea level fluctuations and the MDICE and GICE identified in northern Tarim can be globally correlated to that in southern China, North America, South America, and Europe. The Saergan Fm. source rocks of Middle-Upper Ordovician in Kalpin Dawangou outcrop are in accord with the geologic time of MDICE and ESICE, and GICE have strong ties to the source rock of Lianglitag Fm. in basin. Abundant organic carbon burial is an important factor in genesis of positive isotope carbon excursions. Positive oxygen isotope excursion, conodont fauna turnover, decreased conodont total diversity, and the change of sedimentary facies indicated that dramatic changes of paleoceanographic environment of Early-Middle Ordovician in Tarim Basin started from the end of Darriwillian, and an obvious icehouse climate of Late Ordovician occurred in ESICE.

  6. Fission track analysis and evolution of mesozoic-paleozoic hydrocarbon resource-rocks headed in Northern Jiangsu-South Yellow sea basin

    Fission track data of different geologic epoches from Binhai salient, Yancheng sag, Haian sag, Baiju sag, Gaoyou sag, Hongze sag and Jinhu sag of northern Jiangsu basin and seismic data from Laoshan uplift in South Yellow Sea basin and evolution of Paleozoic hydrocarbon resource-rocks headed in the Northern Jiangsu-South Yellow Sea basin were studied. Results indicate that Binhai salient uplifted in 38-15 Ma, forming 'structure uplifting model', Paleozoic hydrocarbon resource-rocks have the appearance of 'different layers but identical mature, different layers but identical temperature' with Laoshan uplift. All sags have the characters of 'long time heating model', and sedimentations in Cenozoic were exploited by 2 km. Mesozoic-Paleozoic hydrocarbon resource- rocks of Laoshan uplift get ahead of 10 km. Structure evolution was compared with Binhai salient. According to the modeling results of secondary hydrocarbon generation, Mesozoic-Paleozoic hydrocarbon resource-rocks of Laoshan uplift have the good reservoir potentiality and probably become an important new window for sea oil and gas exploration. (authors)

  7. A regional view of urban sedimentary basins in Northern California based on oil industry compressional-wave velocity and density logs

    Brocher, T.M.


    Compressional-wave (sonic) and density logs from 119 oil test wells provide knowledge of the physical properties and impedance contrasts within urban sedimentary basins in northern California, which is needed to better understand basin amplification. These wire-line logs provide estimates of sonic velocities and densities for primarily Upper Cretaceous to Pliocene clastic rocks between 0.1 - and 5.6-km depth to an average depth of 1.8 km. Regional differences in the sonic velocities and densities in these basins largely 1reflect variations in the lithology, depth of burial, porosity, and grain size of the strata, but not necessarily formation age. For example, Miocene basin filling strata west of the Calaveras Fault exhibit higher sonic velocities and densities than older but finer-grained and/or higher-porosity rocks of the Upper Cretaceous Great Valley Sequence. As another example, hard Eocene sandstones west of the San Andreas Fault have much higher impedances than Eocene strata, mainly higher-porosity sandstones and shales, located to the east of this fault, and approach those expected for Franciscan Complex basement rocks. Basement penetrations define large impedence contrasts at the sediment/basement contact along the margins of several basins, where Quaternary, Pliocene, and even Miocene deposits directly overlie Franciscan or Salinian basement rocks at depths as much as 1.7 km. In contrast, in the deepest, geographic centers of the basins, such logs exhibit only a modest impedance contrast at the sediment/basement contact at depths exceeding 2 km. Prominent (up to 1 km/sec) and thick (up to several hundred meters) velocity and density reversals in the logs refute the common assumption that velocities and densities increase monotonically with depth.

  8. Geometry of the El Fresnal basin, northern Chihuahua, Mexico, as inferred from three-dimensional gravity modeling (parte A)

    W. L. Bandy; J. Ortega Ramírez; J. M. Maillol; A. Valiente Banuet; Rodríguez, J. A.


    A multidisciplinary study of the El Fresnal basin, Chihuahua, Mexico is being conducted to investigate the relationships between the structure, vegetation and geomorphology and the Quaternary paleoenvironment. As part of this study, 221 new gravity measurements were collected within the basin and combined with 506 preexisting measurements from the surrounding area to determine the basin geometry and the depth of the sediment infill. A basement-depth model calculated from these data indicates ...

  9. Pockmark development in the Petrel Sub-basin, Timor Sea, Northern Australia: Seabed habitat mapping in support of CO2 storage assessments

    Nicholas, W. A.; Nichol, S. L.; Howard, F. J. F.; Picard, K.; Dulfer, H.; Radke, L. C.; Carroll, A. G.; Tran, M.; Siwabessy, P. J. W.


    The extent to which fluids may leak from sedimentary basins to the seabed is a critical issue for assessing the potential of a basin for carbon capture and storage. The Petrel Sub-basin, located beneath central and eastern Joseph Bonaparte Gulf in tropical northern Australia, was identified as potentially suitable for the geological storage of CO2 because of its geological characteristics and proximity to offshore gas and petroleum resources. In May 2012, a multidisciplinary marine survey (SOL5463) was undertaken to collect data in two targeted areas of the Petrel Sub-basin to facilitate an assessment of its CO2 storage potential. This paper focuses on Area 1 of that survey, a 471 km2 area of sediment-starved shelf (water depths of 78 to 102 m), characterised by low-gradient plains, low-lying ridges, palaeo-channels and shallow pockmarks. Three pockmark types are recognised: small shallow unit pockmarks 10-20 m in diameter (generally mangrove deposits and shells to have begun after 15.5 cal ka BP when a rapid marine transgression of Bonaparte Shelf associated with meltwater pulse 1A drowned coastal mangrove environments. Pockmark development is likely an ongoing process driven by fluid seepage at the seabed, and sourced from CO2 produced in the shallow sub-surface (<2 m) sediment. No evidence for direct connection to deeper features was observed.

  10. Application of the authigenic 10Be/9Be dating method to Late Miocene-Pliocene sequences in the northern Danube Basin (Pannonian Basin System): Confirmation of heterochronous evolution of sedimentary environments

    Šujan, Michal; Braucher, Régis; Kováč, Michal; Bourlès, Didier L.; Rybár, Samuel; Guillou, Valéry; Hudáčková, Natália


    Authigenic 10Be/9Be dating method was applied to lacustrine, deltaic and alluvial sequences of the northern Danube Basin (Pannonian Basin System), to bridge the insufficiency of geochronological data for the Late Miocene to Pliocene period. The measurements of 51 samples (both lacustrine and floodplain), ranging from 11.6 to 0.95 Ma are consistent with the existing magnetostratigraphic and biostratigraphic data standing mainly on the evolution degree of endemic mollusk fauna, mammals and dinocysts. This agreement confirms our assumption that the incoming beryllium fluxes remained constant over the studied time period and thus that the two initial 10Be/9Be ratios determined in actual Holocene/Late Pleistocene sediments (lacustrine and floodplain) are valid for these environments. The obtained ages indicate gradual progradation of the deltaic depositional systems across the Danube Basin with a clear time-transgressional character, replacing basin floor and shelfal environments. Deltaic sedimentation occurred firstly in the north at foothills of the Western Carpathians from 11.0 Ma, and changed to the alluvial environment after 10.5 Ma. At the same time (~ 10.5 Ma), the paleo-Danube deltaic system draining the Eastern Alps entered the study area from the Vienna Basin situated on the West. Later, the deltaic systems were merged in the central part of the basin and reached its southeastern margin at ~ 9.4 Ma. Regression of the Lake Pannon from the southernmost part of the study area is evidenced after 8.7 Ma. Alluvial deposition of meandering rivers lasting until 6.0-5.0 Ma followed and was interrupted by the early Pliocene basin inversion. Sedimentation of braided streams took place during the late Pliocene and Pleistocene, reflecting uplift of mountains surrounding the basin margins. This study documents the powerful potential of the authigenic 10Be/9Be dating method and its reliability in a basin with complicated tectonic and sedimentary history. It demonstrates that