Deposition and diagenesis of the Hibernia member, Jeanne d'Arc Basin, offshore Newfoundland

Energy Technology Data Exchange (ETDEWEB)

Fitzgerald, C E

1987-01-01

The Jeanne d'Arc Basin was formed during Late Triassic to Early Cretaceous time by two episodes of rifting that caused repeated movement on one set of basin-forming faults. This resulted in up to 14 km of sediments, some of which contain huge reserves of hydrocarbons. The Hibernia member, the subject of this thesis, is a sandstone dominated zone within this basin-fill that contains a high proportion of the discovered hydrocarbons. Deposition of the Hibernia member is a result of two simultaneous and related events during Tithonian to Berriasian time: deep erosion of upthrown sides of the fault blocks, and a global eustatic rise of sea level. The provenance and depositional environment are interpreted from the examination of cores, cuttings, microfossils, and thin sections. The siliciclastics were derived from a southern source of sediments and sedimentary rocks that had an original metamorphic origin. They were deposited in a non-marine to brackish water environment of channels and associated floodplains in an anastomosed fluvial system. Rates of sedimentation and subsidence were high, and coupled with a contemporaneous eustatic sea level rise resulted in rapid aggradation and a thick sequence. The center of the basin currently has the highest geothermal gradient and thinnest oil window. Burial and thermal history curves show that the source rocks reached maturity first at the Ben Nevis well; early-formed hydrocarbons may have been lost during tectonic movements in Albian time. The source rocks underlying the Hibernia field are presently at peak oil-generating capability. Organic acids formed during the maturation of organic matter have produced excellent secondary porosity in the sandstones of the Hibernia field. However, at Ben Nevis, subsequent thermal degradation of carboxylic acids allowed late-stage cementation by ferroan calcite cement, destroying the reservoir porosity. 63 refs., 79 figs., 1 tab

SHRIMP zircon U-Pb age and its significances of volcanic rocks from banshi basin in south jiangxi province

International Nuclear Information System (INIS)

Wang Baofeng; Wu Jianhua

2011-01-01

SHRIMP zircon U-Pb dating is applied to geochronological study for tuff of original Jilongzhang formation and rhyolite of original Banshi formation in Banshi basin, located in the Sannan (Longnan, Dingnan, Quannan) -Xunwu volcanic rocks belts in the south of Jiangxi. The result shows that zircon SHRIMP U-Pb age of the tuff is (142.5 ± 1.3) Ma and the age of the rhyolite is (131.4 ± 1.3) Ma. According to the latest international stratigraphic chart, the boundary between Jurassic and Cretaceous is (145.4 ± 4.0) Ma. So original Jilongzhang Formation and original Banshi Formation in Banshi basin were formed during early Early Cretaceous. The volcanic series in Banshi basin belongs to only one volcanic cycle. The features of the rock associations consistent with Wuyi group on the Xiajiang-Guangfeng volcanic rocks belts in the north of Jiangxi, so original Jilongzhang formation falls under E'huling formation and original Banshi formation falls under Shixi formation. (authors)

Geological and 40Ar/39Ar age constraints on late-stage Deccan rhyolitic volcanism, inter-volcanic sedimentation, and the Panvel flexure from the Dongri area, Mumbai

Science.gov (United States)

Sheth, Hetu C.; Pande, Kanchan

2014-04-01

Post-K-Pg Boundary Deccan magmatism is well known from the Mumbai area in the Panvel flexure zone. Represented by the Salsette Subgroup, it shows characters atypical of much of the Deccan Traps, including rhyolite lavas and tuffs, mafic tuffs and breccias, spilitic pillow basalts, and "intertrappean" sedimentary or volcanosedimentary deposits, with mafic intrusions as well as trachyte intrusions containing basaltic enclaves. The intertrappean deposits have been interpreted as formed in shallow marine or lagoonal environments in small fault-bounded basins due to syn-volcanic subsidence. We report a previously unknown sedimentary deposit underlying the Dongri rhyolite flow from the upper part of the Salsette Subgroup, with a westerly tectonic dip due to the Panvel flexure. We have obtained concordant 40Ar/39Ar ages of 62.6 ± 0.6 Ma (2σ) and 62.9 ± 0.2 Ma (2σ) for samples taken from two separate outcrops of this rhyolite. The results are significant in showing that (i) Danian inter-volcanic sedimentary deposits formed throughout Mumbai, (ii) the rock units are consistent with the stratigraphy postulated earlier for Mumbai, (iii) shale fragments known in some Dongri tuffs were likely derived from the sedimentary deposit under the Dongri rhyolite, (iv) the total duration of extrusive and intrusive Deccan magmatism was at least 8-9 million years, and (v) Panvel flexure formed, or continued to form, after 63 Ma, possibly even 62 Ma, and could not have formed by 65-64 Ma as concluded in a recent study.

Electron paramagnetic resonance of rhyolite and γ-irradiated trona minerals

International Nuclear Information System (INIS)

Koeksal, F.; Koeseoglu, R.; Basaran, E.

2003-01-01

Rhyolite from the ''Yellow Stone of Nevsehir'' and γ-irradiated trona from the Ankara Mine have been investigated by electron paramagnetic resonance at ambient temperature and at 113 K. Rhyolite was examined by X-ray powder diffraction and found to consist mainly of SiO 2 . Before γ-irradiation, the existing paramagnetic species in rhyolite were identified as PO 4 2- , CH 2 OH, CO 3 - , SO 2 - , CO 3 3- , and CO 2 - free radicals and Fe 3+ at ambient temperature. At 113 K SO 2 - , CO 3 3- , and CO 2 - radicals and Fe 3+ were observed. The γ-irradiation produced neither new species nor detectable effects on these free radicals. The disappearance of some of the radicals at 113 K is attributed to the freezing of their motions. Before γ-irradiation, the trona mineral shows only Mn 2+ lines, but after γ-irradiation it indicated the inducement of CO 3 3- and CO 2 - radicals at ambient temperature, 113 K, in addition to the Mn 2+ lines. The g and a values of the species were determined. (orig.)

Tectonic-sedimentary evolution of foreland basins: U-Pb dating of the discharge that would have originated the piggy-back basin of Rodeo-Iglesias, San Juan-Argentina

International Nuclear Information System (INIS)

Santos, Romulo Duarte Moreira dos; Hauser, Natalia; Matteini, Massimo; Pimentel, Marcio Martins

2015-01-01

Between the 28 ° and 31 ° LS parallels of the Argentinean west, in the province of San Juan, foreland basins originated by the subhorizontal subduction of oceanic crust as a result of the Andean orogeny in the late Oligocene emerges. The Bermejo basin and Rodeo-Iglesias piggy-back basin would be associated with the progressive development of landslides, backscatter and minor faults, and basin fragmentation. Two samples of volcanic rocks, R-1 (rhyolitic dome) and R-3 (fall deposit) of the Rodeo-Iglesias basin, had ages of 8.2 ± 0.11 Ma and 8.7 ± 0.24 Ma. At the same time, the age of the (R-1) made it possible to infer quantitatively the age of the first cavalcade that occurred approximately 8.2 ± 0.11 Ma. From the data obtained in the Rodeo-Iglesias basin both volcanism and the first cavalcade could have been synchronous

Crustal-scale recycling in caldera complexes and rift zones along the Yellowstone hotspot track: O and Hf isotopic evidence in diverse zircons from voluminous rhyolites of the Picabo volcanic field, Idaho

Science.gov (United States)

Drew, Dana L.; Bindeman, Ilya N.; Watts, Kathryn E.; Schmitt, Axel K.; Fu, Bin; McCurry, Michael

2013-01-01

followed by rapid batch assembly prior to eruption. However, due to the greater abundance of low-δ18O rhyolites at Picabo, the eruptive framework may reflect an intertwined history of caldera collapse and coeval Basin and Range rifting and hydrothermal alteration. We speculate that the source rocks with pre-existing low-δ18O alteration may be related to: (1) deeply buried and unexposed older deposits of Picabo-age or Twin Falls-age low-δ18O volcanics; and/or (2) regionally-abundant late Eocene Challis volcanics, which were hydrothermally altered near the surface prior to or during peak Picabo magmatism. Basin and Range extension, specifically the formation of metamorphic core complexes exposed in the region, could have facilitated the generation of low-δ18O magmas by exhuming heated rocks and creating the large water-rock ratios necessary for shallow hydrothermal alteration of tectonically (rift zones) and volcanically (calderas) buried volcanic rocks. These interpretations highlight the major processes by which supereruptive volumes of magma are generated in the SRP, mechanisms applicable to producing rhyolites worldwide that are facilitated by plume driven volcanism and extensional tectonics.

Radon risk and natural radioactivity of Ziar Basin territory

International Nuclear Information System (INIS)

Urminska, J.; Khun, M.; Jurkovic, L.

1999-01-01

Radon is one of the most important detection elements for assessing the environmental conditions, e.g.in conurbations. The radon radiation waters, and rocks on the Ziar Basin territory [Central Slovakia] was fully studied. Potential risk areas can be found in the vicinity of tectonic faults (verified and supposed). An excess of over 11% of the radon limit concentration was detected in the environment of some buildings. But in terms of high radioactivity Basin region, the dominant position is kept by the rhyolites, rhyodacites and their pyroclastic rocks. Higher values for the 222 Rn volume activity were identified for the samples of waters in rhyolite and granodiorite bodies situated in the tectonic lines of the NE - SW direction. During its transfer through living material the ionizing radiation causes ionization and produces changes in its structure and composition at the same time. This results along with heavy metals in cell death, damage to genetic material, and an increase in the incidence of malignant tumors of the digestation system and lymph-nodes, leukaemia and cancer of the lung. Since 1990, the localities under investigation have shown a higher sickness rate (congenital evolution defects, tumor diseases) when compared to the all-Slovak average

Evolution characteristic of gypsum-salt rocks of the upper member of Oligocene Lower Ganchaigou Fm in the Shizigou area, western Qaidam Basin

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Dinghong Yi

2017-09-01

Full Text Available Over years of oil and gas exploration in the Qaidam Basin, reservoirs have been discovered in many layers. In the Shizigou area, western Qaidam Basin, the upper member of Oligocene Lower Ganchaigou Fm is an important target for oil and gas exploration, and gypsum-salt rocks are the high-quality caprocks for the preservation of oil and gas reservoirs in this area. For predicting oil and gas exploration direction and target in the western Qaidam Basin and providing guidance for its oil and gas exploration deployment, its depositional characteristics and environment of gypsum-salt rocks in this area were investigated based on the core observation, thin section identification, and analysis of grain size, sensitivity parameter ratios (Sr/Cu, Fe/Mn, (Fe + Al/(Ca + Mg, V/(V + Ni and Pr/Ph, pyrite content and inclusions. The following characteristics are identified. First, gypsum-salt rocks are mainly distributed in the depocenter of the lake basin and their thickness decreases towards the margin of the basin. They are laterally transformed into carbonate rocks or terrigenous clastic rocks. They are areally distributed in the shape of irregular ellipse. Second, gypsum-salt rocks are vertically developed mainly in the middle and upper parts of the upper member of Lower Ganchaigou Fm and they are interbedded with carbonate rocks or terrigenous clastic rocks. Their single layer thickness changes greatly, and there are many layers with good continuity. Third, Sand Group III to Group I in the upper member of Lower Ganchaigou Fm (inter-salt are of reductive water environment of semi-deep to deep lake facies due to their sedimentation in an arid and hot climate. It is concluded that gypsum-salt rocks of the upper member of Lower Ganchaigou Fm are distributed widely with great accumulative thickness in this area; and that they are originated from deep lake water by virtue of evaporation, concentration and crystallization in an arid and hot climate instead

U-Pb ages in meta-rhyolite zircon from Arai Group and associated granites

International Nuclear Information System (INIS)

Pimentel, M.M.; Fuck, R.A.

1991-01-01

Geochronology results by V-Pb method in zircon of granite rocks from staniferous province of Goias and rhyolite Arai groups are revealed. Two distinct episode of acid magmatism in Paleo-and Meso proterozoic are presented. V-Pb data in zircon from Sucuri and Soledade granites of the province from Parana River with ages of higher intercepted are also defined. This ages are consider mistakes, similar the V-Pb age of a rhyolite from Arai group. (author)

A compositional tipping point governing the mobilization and eruption style of rhyolitic magma.

Science.gov (United States)

Di Genova, D; Kolzenburg, S; Wiesmaier, S; Dallanave, E; Neuville, D R; Hess, K U; Dingwell, D B

2017-12-13

The most viscous volcanic melts and the largest explosive eruptions on our planet consist of calcalkaline rhyolites. These eruptions have the potential to influence global climate. The eruptive products are commonly very crystal-poor and highly degassed, yet the magma is mostly stored as crystal mushes containing small amounts of interstitial melt with elevated water content. It is unclear how magma mushes are mobilized to create large batches of eruptible crystal-free magma. Further, rhyolitic eruptions can switch repeatedly between effusive and explosive eruption styles and this transition is difficult to attribute to the rheological effects of water content or crystallinity. Here we measure the viscosity of a series of melts spanning the compositional range of the Yellowstone volcanic system and find that in a narrow compositional zone, melt viscosity increases by up to two orders of magnitude. These viscosity variations are not predicted by current viscosity models and result from melt structure reorganization, as confirmed by Raman spectroscopy. We identify a critical compositional tipping point, independently documented in the global geochemical record of rhyolites, at which rhyolitic melts fluidize or stiffen and that clearly separates effusive from explosive deposits worldwide. This correlation between melt structure, viscosity and eruptive behaviour holds despite the variable water content and other parameters, such as temperature, that are inherent in natural eruptions. Thermodynamic modelling demonstrates how the observed subtle compositional changes that result in fluidization or stiffening of the melt can be induced by crystal growth from the melt or variation in oxygen fugacity. However, the rheological effects of water and crystal content alone cannot explain the correlation between composition and eruptive style. We conclude that the composition of calcalkaline rhyolites is decisive in determining the mobilization and eruption dynamics of Earth

A compositional tipping point governing the mobilization and eruption style of rhyolitic magma

Science.gov (United States)

di Genova, D.; Kolzenburg, S.; Wiesmaier, S.; Dallanave, E.; Neuville, D. R.; Hess, K. U.; Dingwell, D. B.

2017-12-01

The most viscous volcanic melts and the largest explosive eruptions on our planet consist of calcalkaline rhyolites. These eruptions have the potential to influence global climate. The eruptive products are commonly very crystal-poor and highly degassed, yet the magma is mostly stored as crystal mushes containing small amounts of interstitial melt with elevated water content. It is unclear how magma mushes are mobilized to create large batches of eruptible crystal-free magma. Further, rhyolitic eruptions can switch repeatedly between effusive and explosive eruption styles and this transition is difficult to attribute to the rheological effects of water content or crystallinity. Here we measure the viscosity of a series of melts spanning the compositional range of the Yellowstone volcanic system and find that in a narrow compositional zone, melt viscosity increases by up to two orders of magnitude. These viscosity variations are not predicted by current viscosity models and result from melt structure reorganization, as confirmed by Raman spectroscopy. We identify a critical compositional tipping point, independently documented in the global geochemical record of rhyolites, at which rhyolitic melts fluidize or stiffen and that clearly separates effusive from explosive deposits worldwide. This correlation between melt structure, viscosity and eruptive behaviour holds despite the variable water content and other parameters, such as temperature, that are inherent in natural eruptions. Thermodynamic modelling demonstrates how the observed subtle compositional changes that result in fluidization or stiffening of the melt can be induced by crystal growth from the melt or variation in oxygen fugacity. However, the rheological effects of water and crystal content alone cannot explain the correlation between composition and eruptive style. We conclude that the composition of calcalkaline rhyolites is decisive in determining the mobilization and eruption dynamics of Earth�

Lithium deposits hosted in intracontinental rhyolite calderas

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Benson, T. R.; Coble, M. A.; Mahood, G. A.

2017-12-01

Lithium (Li) is classified as a technology-critical element due to the increasing demand for Li-ion batteries, which have a high power density and a relatively low cost that make them optimal for energy storage in mobile electronics, the electrical power grid, and hybrid and electric vehicles. Given that many projections for Li demand exceed current economic reserves and the market is dominated by Australia and Chile, discovery of new domestic Li resources will help diversify the supply chain and keep future technology costs down. Here we show that lake sediments preserved within intracontinental rhyolite calderas have the potential to host Li deposits on par with some of the largest Li brine deposits in the world. We compare Li concentrations of rhyolite magmas formed in a variety of tectonic settings using in situ SHRIMP-RG measurements of homogenized quartz-hosted melt inclusions. Rhyolite magmas that formed within thick, felsic continental crust (e.g., Yellowstone and Hideaway Park, United States) display moderate to extreme Li enrichment (1,500 - 9,000 ppm), whereas magmas formed in thin crust or crust comprised of accreted arc terranes (e.g., Pantelleria, Italy and High Rock, Nevada) contain Li concentrations less than 500 ppm. When the Li-enriched magmas erupt to form calderas, the cauldron depression serves as an ideal catchment within which meteoric water that leached Li from intracaldera ignimbrite, nearby outflow ignimbrite, and caldera-related lavas can accumulate. Additional Li is concentrated in the system through near-neutral, low-temperature hydrothermal fluids circulated along ring fractures as remnant magma solidifies and degasses. Li-bearing hectorite and illite clays form in this alteration zone, and when preserved in the geological record, can lead to a large Li deposit like the 2 Mt Kings Valley Li deposit in the McDermitt Caldera, Nevada. Because more than 100 large Cenozoic calderas occur in the western United States that formed on eruption

Characteristics of Young Rhyolites at Taupo, New Zealand: Implications for the Sub-Surface Plutonic System

Science.gov (United States)

Wilson, C. J.; Charlier, B. L.

2007-12-01

The young history of Taupo volcano captures the growth and destruction in the 26.5 ka ca. 530 km3 Oruanui eruption of a large rhyolitic magma body, together with the subsequent rejuvenation of magma sources below the volcano. Integration of field information with petrological and isotopic studies at the whole-pumice and single- crystal scales provide a picture of this history. Several important contrasts are inferred to exist between Taupo and comparably-sized, long-lived silicic foci such at Long Valley and in the Bishop Tuff. At Taupo the following are demonstrable. 1. Even in crystal-poor rhyolites like the Oruanui, many grains are inherited antecrysts or xenocrysts. The Oruanui crystal-poor rhyolite body was an open system, with influxes of crystals (plus melt) from remobilised older crystal mush, melted metasedimentary country rocks and plutonics, and crystal-poor basaltic to andesitic magmas. 2. All the Taupo rhyolites were well mixed prior to eruption, and there are no gradients in the eruption products to suggest that the holding chamber(s) were stratified to any extent. 3. Mafic magmas rose into, interacted with, and ponded on the floors of crystal-poor rhyolite in the Oruanui and Waimihia (3.5 ka) examples, again implying that the chamber floor was sharply defined, not a gradual progression down into a more crystal- rich root zone. 4. Pre-Oruanui activity involved contrasting magma types being generated simultaneously, but erupting from geographically separated vents. Post-Oruanui activity has seen (subtly) contrasting magma groups being erupted from vents in the same geographic area, but separated in time. The Oruanui and post-Oruanui magmas are different and do not appear to be related by consanguinity or by mixing - the Oruanui eruption effectively destroyed its magma body. These features are consistent with rhyolite magma generation at Taupo that is exceptionally fast, driven by high fluxes of mafic magmas into a highly heterogeneous crustal melange

New insights into the origin of the bimodal volcanism in the middle Okinawa Trough: not a basalt-rhyolite differentiation process

Science.gov (United States)

Zhang, Yuxiang; Zeng, Zhigang; Chen, Shuai; Wang, Xiaoyuan; Yin, Xuebo

2018-06-01

In the middle Okinawa Trough (MOT), rhyolites have been typically considered as products of crystallization differentiation of basaltic magma as a feature of bimodal volcanism. However, the evidence is insufficient. This paper compared chemical trends of volcanic rocks from the MOT with fractional crystallization simulation models and experimental results and utilized trace element modeling combined with Rayleigh fractionation calculations to re-examine fractional crystallization processes in generating rhyolites. Both qualitative and quantitative studies indicate that andesites, rather than rhyolites, originate by fractional crystallization from basalts in the MOT. Furthermore, we established two batch-melting models for the MOT rhyolites and proposed that type 1 rhyolites are produced by remelting of andesites with amphiboles in the residue, while type 2 rhyolites are derived from remelting of andesites without residual amphiboles. It is difficult to produce melts with a SiO2 content ranging from 62% to 68% either by magmatic differentiation from basalts or by remelting of andesites, and this difficulty might help account for the compositional gap (Daly gap) for bimodal volcanism in the Okinawa Trough.

Status of image analysis methods to delineate stratigraphic position in the Topopah Spring Member of the Paintbrush Tuff, Yucca Mountain, Nye County, Nevada

International Nuclear Information System (INIS)

Campbell, K.; Broxton, D.E.; Spaw, J.

1989-10-01

The Topopah Spring Member of the Paintbrush Tuff is an ash-flow cooling unit that is the candidate host rock for a potential high-level nuclear waste repository at Yucca Mountain, Nevada. The repository workings will be mostly confined to the member's rhyolitic portion, which is chemically homogenous but texturally variable. This report describes the status of work to develop a useful internal stratigraphy for the rhyolitic portion of the member; our approach is to use an image analysis technique to map textural variations within the member as a function of stratigraphic height. Fifteen petrographic thin sections of Topopah Spring rhyolitic tuff were studied in each of two drill holes (USW GU-3 and USW G-4). Digital color images were collected in transmitted light for two scenes 1 cm on a side for each thin section. Objects within a scene were classified by color, and measurements of area, elongation, and roughness were determined for each object. Summary statistics were compiled for all measurements for each color component within a scene, and each variable was statistically examined for correlations with stratigraphic position. Our initial studies using image analysis have not yet produced a useful method for determining stratigraphic position within the Topopah Spring Member. Simplifications made in this preliminary application of image analysis may be largely responsible for these negative results. The technique deserves further investigation, and more detailed analysis of existing data is recommended. 9 refs., 11 figs., 4 tabs

Relationship between natural radioactivity and rock type in the Van lake basin - Turkey

International Nuclear Information System (INIS)

Tolluoglu, A. U.; Eral, M.; Aytas, S.

2004-01-01

The Van Lake basin located at eastern part of Turkey. The Van lake basin essentially comprises two province, these are namely Van and Bitlis. The former geochemistry research indicated that the uranium concentrations of Van lake water and deep sediments are 78-116 ppb and 0.1-0.5 ppm respectively. Uranium was transported to Van Lake by rivers and streams, flow through to outcrops of Paleozoic Bitlis Massive, and young Pleistocene alkaline/calkalkaline volcanic rocks. This study focused on the revealing natural radioactivity and secondary dispersion of radioactivity related to rock types surface environments in the Van Lake Basin. The Van Lake Basin essentially subdivided into three different parts; the Eastern parts characterized by Mesozoic basic and ultra basic rocks, southern parts dominated by metamorphic rocks of Bitlis Massive, Western and Northwestern parts covered by volcanic rocks of Pleistocene. Volcanic rocks can be subdivided into two different types. The first type is mafic rocks mainly composed of basalts. The second type is felsic rocks represented by rhyolites, dacites and pumice tuff. Surface gamma measurements (cps) and dose rate measurements (μR/h) show different values according to rock type. Surface gamma measurement and surface dose rate values in the basaltic rocks are slightly higher than the average values (130 cps, 11 μR/h). In the felsic volcanic rocks such as rhyolites and dacites surface gamma measurement values and surface dose rate values, occasionally exceed the background. Highest values were obtained in the pumice tuffs. Rhyolitic eruptions related to Quaternary volcanic activity formed thick pumice (natural glassy froth related to felsic volcanic rocks and exhibit spongy texture) sequences Northern and Western part of Van Lake basin. The dose rate of pumice rocks was measured mean 15 μR/h. The highest value for surface gamma measurements was recorded as 200 cps. The pumice has very big water capacity, due to porous texture of

Cooling and crystallization of rhyolite-obsidian lava: Insights from micron-scale projections on plagioclase microlites

Science.gov (United States)

Sano, Kyohei; Toramaru, Atsushi

2017-07-01

To reveal the cooling process of a rhyolite-obsidian flow, we studied the morphology of plagioclase microlites in the Tokachi-Ishizawa lava of Shirataki, northern Hokkaido, Japan, where the structure of the lava can be observed from obsidian at the base of the flow to the innermost rhyolite. Needle-like micron-scale textures, known as "projections", occur on the short side surfaces of the plagioclase microlites. Using FE-SEM we discovered a positive correlation between the lengths and spacings of these projections. On the basis of the instability theory of an interface between melt and crystal, and to understand the length and spacing data, we developed a model that explains the positive correlation and allows us to simultaneously estimate growth rates and growth times. Applying the model to our morphological data and the estimated growth rates and growth times, we suggest that the characteristics of the projections reflect the degree of undercooling, which in turn correlates with lava structure (the obsidian at the margin of the flow experienced a higher degree of undercooling than the interior rhyolite). The newly developed method provides insights into the degree of undercooling during the final stages of crystallization of a rhyolitic lava flow.

Stratigraphic position of the rhyolitic in the Upper Rotliegende of the Saar-Nahe-area and the uranium content of the coal-tuff-horizon at the Kornkiste near Schallodenbach/Pfalz (SW Germany)

Energy Technology Data Exchange (ETDEWEB)

Haneke, J; Gaede, C W [Gewerkschaft Brunhilde, Uetze (Germany, F.R.); Lorenz, V [Mainz Univ. (Germany, F.R.). Inst. fuer Geowissenschaften

1979-01-01

The lithostratigraphic sequence of the Upper Rotliegende rocks of the SE-flank of the Palatinate anticline (Saar-Nahe-basin, SW Germany) is described using as index horizons six principal rhyolitic tuff layers (1-VI) and several basic to intermediate lava flows. Coal and bentonite beds are developed at the base of rhyolite tuff III at the Kornkiste near Schallodenbach. In this basal sequence anomalous U/sub 3/O/sub 8/, Cu, Pb, Zn contents have been detected. Cu occurs in part as azurite and malachite. The major amount of the investigated elements appears to occur in form of organic complexes or compounds in the coals. In addition these elements seem to have been absorbed by the bentonite clay minerals. The elements U, Cu, Pb show a clear positive correlation between each other wheres Zn correlators negatively with these elements. The U-Cu-Pb-Zn-enrichment is believed to have been caused by descending aqueous solutions.

Educational utilization of outstanding spherulitic rhyolite occurred in Cheongsong, Korea

Science.gov (United States)

Jang, Y. D.; Woo, H.

2015-12-01

Cheongsong is located in the central eastern area of South Korea. Unique spherulitic rhyolites occur in this region as dykes formed about 48 to 50 million years ago. Composed of quartz and feldspar these spherulitic rhyolites show various flowerlike shapes, such as chrysanthemum, dandelion, rose, carnation, sunflower, dahlia and so on, so they are called 'flower stones'. The spherulite indicates that it was undercooled caused by very fast cooling at a shallow depth near the surface and the variety of shapes resulted from the difference of crystallizing conditions. According to the condition, minerals start to crystallize homogeneously or heterogeneously and develop as rounded or fibrous shapes, representing beautiful patterns when combined. These spherulitic structures are very rare not only in Korea but also globally, being valuable for research and preservation because of their rarity, beauty and diversity. Cheongsong therefore applies to the UGG (UNESCO Global Geopark) in an attempt to popularize the flower stones and use them as education materials which can also be incorporated in other valuable sites. The exhibition center provides diverse types of flower stones in which visitors could learn about rhyolitic volcanism, crystallization and spherulite and can experience the process of changing a rough stone into a flower stone. A geotrail course has also been created, showing each type of flower stone on the outcrop and providing educational programs about geological mechanisms of the stones with a trained guide.

Cerro Amarillo rhyolites, advanced AFC in the northern SVZ, Chile

International Nuclear Information System (INIS)

Godoy, E; Hildreth, W

2001-01-01

Cerro Amarillo is a Quaternary medium size (500m high, 2 km 2 ) rhyolite dome complex located close to the Chile-Argentina border, reaching a height of 4162 m, between the headwaters of the Rio Colina and the Nieves Negras Pass. It overlies a broad anticline of thick Middle Jurassic pelites (Alvarez et al., 1997). Thiele (1980) includes this complex in his 'Unidad Volcanica Antigua', a Pleistocene composite map unit made up of andesites and trachyandesites. Ramos et al. (1997), while recognizing its rhyolitic character, assigned a Tertiary age to the lava domes, most likely based on the late Pliocene age of silicic dikes outcropping eastward, in Argentina. Both the lack of younger overlying units and freshness of its components, together with preservation of the unconsolidated, easily eroded pyroclastic deposits at its base, suggest, however, that it is not older than Pleistocene (au)

Drilling into Rhyolitic Magma at Shallow depth at Krafla Volcanic Complex, NE-Iceland

Science.gov (United States)

Mortensen, A. K.; Markússon, S. H.; Gudmundsson, Á.; Pálsson, B.

2017-12-01

Krafla volcanic complex in NE-Iceland is an active volcano but the latest eruption was the Krafla Fires in 1975-1984. Though recent volcanic activity has consisted of basaltic fissure eruptions, then it is rhyolitic magma that has been intercepted on at least two occasions while drilling geothermal production wells in the geothermal field suggesting a layered magma plumbing system beneath the Krafla volcanic complex. In 2008 quenched rhyolitic glass was retrieved from the bottom of well KJ-39, which is 2865 m deep ( 2571 m true vertical depth). In 2009 magma was again encountered at an even shallower depth and in more than 2,5 km distance from the bottom of well KJ-39, but in 2009 well IDDP-1 was drilled into magma three times just below 2100 m depth. Only on the last occasion was quenched glass retrieved to confirm that magma had been encountered. In well KJ-39 the quenched glass was rhyolitic in composition. The glass contained resorbed minerals of plagioclase, clinopyroxene and titanomagnetite, but the composition of the glass resembles magma that has formed by partial melting of hydrated basalt. The melt was encountered among cuttings from impermeable, coarse basaltic intrusives at a depth, where the well was anticipated to penetrate the Hólseldar volcanic fissure. In IDDP-1 the quenched glass was also rhyolitic in composition. The glass contained less than 5% of phenocrysts, but the phenocryst assemblage included andesine plagioclase, augite, pigeonite, and titanomagnetite. At IDDP-1 the melt was encountered below a permeable zone composed of fine to coarse grained felsite and granophyre. The disclosure of magma in two wells at Krafla volcanic complex verify that rhyolitic magma can be encountered at shallow depth across a larger area within the caldera. The encounter of magma at shallow depth conforms with that superheated conditions have been found at >2000 m depth in large parts of Krafla geothermal field.

The stratigraphic position of the rhyolitic in the Upper Rotliegende of the Saar-Nahe-area and the uranium content of the coal-tuff-horizont at the Kornkiste near Schallodenbach/Pfalz (SW Germany)

International Nuclear Information System (INIS)

Haneke, J.; Gaede, C.W.; Lorenz, V.

1979-01-01

The lithostratigraphic sequence of the Upper Rotliegende rocks of the SE-flank of the Palatinate anticline (Saar-Nahe-basin, SW Germany) is described using as index horizons six principal rhyolitic tuff layers (1-VI) and several basic to intermediate lava flows. Coal and bentonite beds are developed at the base of rhyolite tuff III at the Kornkiste near Schallodenbach. In this basal sequence anomalous U 3 O 8 , Cu, Pb, Zn contents have been detected. Cu occurs in part as azurite and malachite. The major amount of the investigated elements appears to occur in form of organic complexes or compounds in the coals. In addition these elements seem to have been absorbed by the bentonite clay minerals. The elements U, Cu, Pb show a clear positive correlation between each other wheres Zn correlators negatively with these elements. The U-Cu-Pb-Zn-enrichment is believed to have been caused by descending aqueous solutions. (orig.) [de

Dynamics of a large, restless, rhyolitic magma system at Laguna del Maule, southern Andes, Chile

Science.gov (United States)

Singer, Brad S.; Andersen, Nathan L.; Le Mével, Hélène; Feigl, Kurt L.; DeMets, Charles; Tikoff, Basil; Thurber, Clifford H.; Jicha, Brian R.; Cardonna, Carlos; Córdova, Loreto; Gil, Fernando; Unsworth, Martyn J.; Williams-Jones, Glyn; Miller, Craig W.; Fierstein, Judith; Hildreth, Edward; Vazquez, Jorge A.

2014-01-01

Explosive eruptions of large-volume rhyolitic magma systems are common in the geologic record and pose a major potential threat to society. Unlike other natural hazards, such as earthquakes and tsunamis, a large rhyolitic volcano may provide warning signs long before a caldera-forming eruption occurs. Yet, these signs—and what they imply about magma-crust dynamics—are not well known. This is because we have learned how these systems form, grow, and erupt mainly from the study of ash flow tuffs deposited tens to hundreds of thousands of years ago or more, or from the geophysical imaging of the unerupted portions of the reservoirs beneath the associated calderas. The Laguna del Maule Volcanic Field, Chile, includes an unusually large and recent concentration of silicic eruptions. Since 2007, the crust there has been inflating at an astonishing rate of at least 25 cm/yr. This unique opportunity to investigate the dynamics of a large rhyolitic system while magma migration, reservoir growth, and crustal deformation are actively under way is stimulating a new international collaboration. Findings thus far lead to the hypothesis that the silicic vents have tapped an extensive layer of crystal-poor, rhyolitic melt that began to form atop a magmatic mush zone that was established by ca. 20 ka with a renewed phase of rhyolite eruptions during the Holocene. Modeling of surface deformation, magnetotelluric data, and gravity changes suggest that magma is currently intruding at a depth of ~5 km. The next phase of this investigation seeks to enlarge the sets of geophysical and geochemical data and to use these observations in numerical models of system dynamics.

Morphostructural characterization of the Charco basin and its surrounding areas in the Chihuahua segment of north Mexican Basin and Range Province

Science.gov (United States)

Troiani, Francesco; Menichetti, Marco

2014-05-01

The Chihuahua Basin and Range (CBR) is the eastern branch of the northern Mexican Basin and Range Province that, from a morphostructural point of view, presently is one amongst the lesser-known zones of the southern portion of the North America Basin and Range Province. The study area covers an approximately 800 km2-wide portion of the CBR and encompasses the fault-bounded Charco basin and its surrounding areas. The bedrock of the area pertains to the large siliceous-igneous province of the Sierra Madre Occidental and consists of volcanoclastic rocks including Oligocene dacite, rhyolite, rhyolitic tuffs, and polimitic conglomerates. The region is characterized by a series of NW-SE oriented valleys delimited by tilted monoclinal blocks bounded by high angle, SW-dipping, normal faults. Abrupt changes in elevation, alternating between narrow faulted mountain chains and flat arid valleys or basins are the main morphological elements of the area. The valleys correspond to structural grabens filled with Plio-Pleistocene continental sediments. These grabens are about 10 km wide, while the extensional fault system extend over a distance of more than 15 km. The mountain ranges are in most cases continuous over distances that range from 10 to 70 km including different branches of the extensional and transfer faults. The morphogenesis is mainly erosive in character: erosional landforms (such as rocky scarps, ridges, strath-terraces, erosional pediment, reverse slopes, landslide scar zones, litho-structural flat surfaces) dominate the landscape. In contrast, Quaternary depositional landforms are mainly concentrated within the flat valleys or basins. The Quaternary deposits consist of wide alluvial fans extending to the foot of the main ridges, fluvial and debris-slope deposits. The morphostructural characterization of the area integrated different methodologies, including: i) geomorphological and structural field analyses; ii) remote sensing and geo-morphometric investigations

Argon Diffusion Measured in Rhyolite Melt at 100 MPa

Science.gov (United States)

Weldon, N.; Edwards, P. M.; Watkins, J. M.; Lesher, C. E.

2016-12-01

Argon diffusivity (D_{Ar} ) controls the rate and length scale of argon exchange between melt and gas phases and is used as a parameter to model noble gas fractionation during magma degassing. D_{Ar} may also be useful in geochronology to estimate the distribution of excess (non-radiogenic) atmospheric argon in lavas. Our measurements of D_{Ar} in molten anhydrous rhyolite near 1000 °C and 100 MPa add to the existing dataset. Using a rapid-quench cold seal pressure apparatus we exposed cylindrical charges drilled from a Miocene rhyolite flow near Buck Mtn., CA to a pure argon atmosphere resulting in a gradually lengthening argon concentration gradient between the saturated surface and the argon poor interior. Argon concentration was measured by electron microprobe along radial transects from the center to the surface of bisected samples. D_{Ar} was calculated for each transect by fitting relative argon concentration (as a function of distance from the surface) to Green's function (given each experiment's specific temperature, pressure and runtime). Variability (σ = 1.202{μm }^{2} /s) was smaller than in previous studies, but still greater than what is likely due to analytical or experimental uncertainty. We observed a symmetric geometric bias in the distribution of argon in our samples, possibly related to advective redistribution of argon accompanying the deformation of cylindrical charges into spheroids driven by surface tension. Average diffusivity, D_{Ar} = 4.791{μm }^{2} /s, is close to the predicted value, D_{Ar} = {μm }^{2} /s ( σ_{ \\bar{x} } = 1.576 {μm }^{2} /s), suggesting that Behrens and Zhang's (2001) empirical model is valid for anhydrous rhyolite melts to relatively higher temperatures and lower pressures. Behrens, H. and Y. Zhang (2001). "Ar diffusion in hydrous silicic melts: implications for volatile diffusion mechanisms and fractionation." Earth and Planetary Science Letters 192: 363-376.

Discovery of uranium mineralizations in the rhyolite-granite complex in the Jabal Eghei area of southern Libya

Directory of Open Access Journals (Sweden)

Kovačević Jovan

2013-01-01

Full Text Available During investigation of the Jabal Eghei area in southern Libya and the production of geological maps at a scale of 1:250 000 (Tibesti sector, sheet Wadi Eghei NF 34-1 and NF 34-2, regional prospecting for mineral raw materials was performed. Radiometric survey of observed targets at the sites indicated two significant uranium mineralizations in rhyolites, and some smaller ones in granites that are in close contact with rhyolites. Rhyolites are located in the central part of the investigated region. They cut through granite rocks. The first mineralization is in the central part of the rhyolite region, which is mostly composed of silificated rhyolites. The second one was discovered near the granite-rhyolite contact zone, characterized by the presence of silicified breccia rocks. These findings were confirmed by laboratory measurements of more than seventy samples collected in the area, using high resolution gamma-ray spectrometry. The concentrations of uranium in these mineralizations were found to range from approx. 50 mg kg-1 to more than 600 mg kg-1. The latter value is about 240 times above the Earth’s average. Besides uranium, these measurements have also given concentrations of thorium and potassium. Additional geochemical analysis was performed on samples taken from locations where uranium anomalies were discovered using ICP-MS technique, in which concentrations of more than forty elements were determined. Uranium mineralizations are accompained by increased contents of silver (up to 17 times, arsenic (up to 8 times, molybdenum (up to 50 times, mercury (up to 9 times, and lead (up to 14 times, in regard to the Clark’s values. These results warrant a continued investigation of this region because of potential interest in the discovery of nuclear mineral raw materials.

Contrasting origin of two A-type rhyolite series from the Early Permian Nomgon bimodal volcanic association (Southern Mongolia)

Science.gov (United States)

Kozlovsky, A. M.; Yarmolyuk, V. V.; Savatenkov, V. M.; Kudryashova, E. A.

2017-08-01

A-type rhyolites of contrasting compositions and eruption characters were revealed among two volcanic series of the Early Permian bimodal association in the Nomgon graben. Rhyolites of the lower volcanic series formed extrusions, lava domes, and tuff horizons. They had low FeOt, Zr, Hf, Nb, Ta, Y, and REE concentrations and also a moderately depleted Nd isotope composition (ɛNd( T) = 6.7-7.1). Their formation was related to anatexis of the juvenile continental crust, triggered by the thermal effect of mafic magmas. Rhyolites of the upper volcanic series formed extensive lava flows and dikes. Their composition was characterized by high FeOt, Zr, Hf, Nb, Ta, Y, and REE concentrations, and also depleted Nd isotope characteristics (ɛNd( T) = 7.7-9.0). These rhyolite melts formed under long-term crystallizational differentiation of basaltoids in the intracrustal magmatic chambers, with limited participation of crustal contamination. The source of magmas for the upper volcanic series was the sublithospheric mantle.

Expanding Geophysical and Geochemical Investigation of Causes of Extraordinary Unrest at the Laguna del Maule (Rhyolitic) Volcanic Field, Southern Andes, Chile

Science.gov (United States)

Singer, B. S.

2014-12-01

The Laguna del Maule Volcanic Field, Chile, includes an unusually large and recent concentration of silicic eruptions. Since 2007 the crust here has been inflating at an astonishing rate of 25 cm/yr. Findings thus far lead to the hypothesis that the silicic vents have tapped an extensive layer of crystal-poor, rhyolitic melt that began to form atop a magmatic mush zone that was established by ~20 ka with a renewed phase of rhyolite eruptions during the Holocene. Modeling of surface deformation, magnetotelluric data, and gravity changes suggest that magma is currently intruding at a depth of ~5 km. Swarms of volcano-tectonic and long period earthquakes, mostly of M San Juan-Argentina, Nanyang Technological University-Singapore, SERNAGEOMIN, OVDAS, USGS, and SEGEMAR-Argentina. Team members will be introduced in this presentation. Our approach includes augmenting the OVDAS array of 6 permanent seisic stations with 40 additional instruments to conduct tomographic, receiver function and ambient noise studies. We continue to collect 4-D gravity data from 37 stations. Surface deformation is monitored via cGPS at 5 permanent receivers and InSAR data. A magnetotelluric survey across the Andes at 36o S is planned. Geochemical studies include mineral zoning and U-Th disequilibrium of zircons to constrain the timing of magma intrusion and mixing events prior to the current unrest. The overall aim is to integrate these observations and to construct numerical models of system dynamics. We are developing communications protocols and a web site to facilitate sharing of findings among the team members and with the public.

Mineralogy and geothermometry of high-temperature rhyolites from the central and western Snake River Plain

Science.gov (United States)

Honjo, N.; Bonnichsen, B.; Leeman, W.P.; Stormer, J.C.

1992-01-01

Voluminous mid-Miocene rhyolitic ash-flow tuffs and lava flows are exposed along the northern and southern margins of the central and western Snake River Plain. These rhyolites are essentially anhydrous with the general mineral assemblage of plagioclase ??sanidine ?? quartz + augite + pigeonite ?? hypersthene ?? fayalitic olivine + Fe-Ti oxides + apatite + zircon which provides an opportunity to compare feldspar, pyroxene, and Fe-Ti oxide equilibration temperatures for the same rocks. Estimated pyroxene equilibration temperatures (based on the geothermometers of Lindsley and coworkers) range from 850 to 1000??C, and these are well correlated with whole-rock compositions. With the exception of one sample, agreement between the two-pyroxene thermometers tested is well within 50??C. Fe-Ti oxide geothermometers applied to fresh magnetite and ilmenite generally yield temperatures about 50 to 100??C lower than the pyroxene temperatures, and erratic results are obtained if these minerals exhibit effects of subsolidus oxidation and exsolution. Results of feldspar thermometry are more complicated, and reflect uncertainties in the thermometer calibrations as well as in the degree of attainment of equilibrium between plagioclase and sanidine. In general, temperatures obtained using the Ghiorso (1984) and Green and Usdansky (1986) feldspar thermometers agree with the pyroxene temperatures within the respective uncertainties. However, uncertainties in the feldspar temperatures are the larger of the two (and exceed ??60??C for many samples). The feldspar thermometer of Fuhrman and Lindsley (1988) produces systematically lower temperatures for many of the samples studied. The estimated pyroxene temperatures are considered most representative of actual magmatic temperatures for these rhyolites. This range of temperatures is significantly higher than those for rhyolites from many other suites, and is consistent with the hypothesis that the Snake River Plain rhyolitic magmas formed

Possible two-stage 87Sr evolution in the Stockdale Rhyolite

International Nuclear Information System (INIS)

Compston, W.; McDougall, I.; Wyborn, D.

1982-01-01

The Rb-Sr total-rock data for the Stockdale Rhyolite, of significance for the Palaeozoic time scale, are more scattered about a single-stage isochron than expected from experimental error. Two-stage 87 Sr evolution for several of the samples is explored to explain this, as an alternative to variation in the initial 87 Sr/ 86 Sr which is customarily used in single-stage dating models. The deletion of certain samples having very high Rb/Sr removes most of the excess scatter and leads to an estimate of 430 +- 7 m.y. for the age of extrusion. There is a younger alignment of Rb-Sr data within each sampling site at 412 +- 7 m.y. We suggest that the Stockdale Rhyolite is at least 430 m.y. old, that its original range in Rb/Sr was smaller than now observed, and that it experienced a net loss in Sr during later hydrothermal alteration at ca. 412 m.y. (orig.)

Rheomorphic ignimbrites of the Rogerson Formation, central Snake River plain, USA

DEFF Research Database (Denmark)

Knott, Thomas R.; Reichow, Marc K.; Branney, Michael J.

2016-01-01

Rogerson Graben, USA, is critically placed at the intersection between the Yellowstone hotspot track and the southern projection of the west Snake River rift. Eleven rhyolitic members of the re-defined, ≥420-m-thick, Rogerson Formation record voluminous high-temperature explosive eruptions....... Between 11.9 and ∼8 Ma, the average frequency of large explosive eruptions in this region was 1 per 354 ky, about twice that at Yellowstone. The chemistry and mineralogy of the early rhyolites show increasing maturity with time possibly by progressive fractional crystallisation. This was followed......-margin monocline, which developed between 10.59 and 8 Ma. The syn-volcanic basin topography contrasted significantly with the present-day elevated Yellowstone hotspot plateau. Concurrent basin-and-range extension produced the N-trending Rogerson Graben: early uplift of the Shoshone Hills (≥10.34 Ma) was followed...

The petrologic evolution and pre-eruptive conditions of the rhyolitic Kos Plateau Tuff (Aegean arc)

Science.gov (United States)

Bachmann, Olivier

2010-09-01

The Kos Plateau Tuff is a large (>60 km3) and young (160 k.y.) calc-alkaline, high-SiO2 rhyolitic ignimbrite from the active Kos-Nisyros volcanic center in the Aegean arc (Greece). Combined textural, petrological and geochemical information suggest that (1) the system evolved dominantly by crystal fractionation from (mostly unerupted) more mafic parents, (2) the magma chamber grew over ≥ 250 000 years at shallow depth (˜1.5-2.5 kb) and was stored as a H2O-rich crystalline mush close to its solidus (˜670-750°C), (3) the eruption occurred after a reheating event triggered by the intrusion of hydrous mafic magma at the base of the rhyolitic mush. Rare banded pumices indicate that the mafic magma only mingled with a trivial portion of resident crystal-rich rhyolite; most of the mush was remobilized following partial melting of quartz and feldspars induced by advection of heat and volatiles from the underplated, hotter mafic influx.

Two types of gabbroic xenoliths from rhyolite dominated Niijima volcano, northern part of Izu-Bonin arc: petrological and geochemical constraints

Science.gov (United States)

Arakawa, Yoji; Endo, Daisuke; Ikehata, Kei; Oshika, Junya; Shinmura, Taro; Mori, Yasushi

2017-03-01

We examined the petrography, petrology, and geochemistry of two types of gabbroic xenoliths (A- and B-type xenoliths) in olivine basalt and biotite rhyolite units among the dominantly rhyolitic rocks in Niijima volcano, northern Izu-Bonin volcanic arc, central Japan. A-type gabbroic xenoliths consisting of plagioclase, clinopyroxene, and orthopyroxene with an adcumulate texture were found in both olivine basalt and biotite rhyolite units, and B-type gabbroic xenoliths consisting of plagioclase and amphibole with an orthocumulate texture were found only in biotite rhyolite units. Geothermal- and barometricmodelling based on mineral chemistry indicated that the A-type gabbro formed at higher temperatures (899-955°C) and pressures (3.6-5.9 kbar) than the B-type gabbro (687-824°C and 0.8-3.6 kbar). These findings and whole-rock chemistry suggest different parental magmas for the two types of gabbro. The A-type gabbro was likely formed from basaltic magma, whereas the B-type gabbro was likely formed from an intermediate (andesitic) magma. The gabbroic xenoliths in erupted products at Niijima volcano indicate the presence of mafic to intermediate cumulate bodies of different origins at relatively shallower levels beneath the dominantly rhyolitic volcano.

238U-230Th dating of chevkinite in high-silica rhyolites from La Primavera and Yellowstone calderas

Science.gov (United States)

Vazquez, Jorge A.; Velasco, Noel O.; Schmitt, Axel K.; Bleick, Heather A.; Stelten, Mark E.

2014-01-01

Application of 238U-230Th disequilibrium dating of accessory minerals with contrasting stabilities and compositions can provide a unique perspective on magmatic evolution by placing the thermochemical evolution of magma within the framework of absolute time. Chevkinite, a Th-rich accessory mineral that occurs in peralkaline and metaluminous rhyolites, may be particularly useful as a chronometer of crystallization and differentiation because its composition may reflect the chemical changes of its host melt. Ion microprobe 128U-230Th dating of single chevkinite microphenocrysts from pre- and post-caldera La Primavera, Mexico, rhyolites yields model crystallization ages that are within 10's of k.y. of their corresponding K-Ar ages of ca. 125 ka to 85 ka, while chevkinite microphenocrysts from a post-caldera Yellowstone, USA, rhyolite yield a range of ages from ca. 110 ka to 250 ka, which is indistinguishable from the age distribution of coexisting zircon. Internal chevkinite-zircon isochrons from La Primavera yield Pleistocene ages with ~5% precision due to the nearly two order difference in Th/U between both minerals. Coupling chevkinite 238U-230Th ages and compositional analyses reveals a secular trend of Th/U and rare earth elements recorded in Yellowstone rhyolite, likely reflecting progressive compositional evolution of host magma. The relatively short timescale between chevkinite-zircon crystallization and eruption suggests that crystal-poor rhyolites at La Primavera were erupted shortly after differentiation and/or reheating. These results indicate that 238U-230Th dating of chevkinite via ion microprobe analysis may be used to date crystallization and chemical evolution of silicic magmas.

Rhyolites associated to Ethiopian CFB: Clues for initial rifting at the Afar plume axis

Science.gov (United States)

Natali, Claudio; Beccaluva, Luigi; Bianchini, Gianluca; Siena, Franca

2011-12-01

A comprehensive tectono-magmatic model based on new geochemical and field data is discussed in order to highlight the significance of the high-TiO 2 bimodal picrite basalt/rhyolite association in the north-eastern sector of the Ethiopian Plateau, which is considered to be the axial zone of the 30 Ma Continental Flood Basalt activity related to the Afar plume (Beccaluva et al., 2009). In this area the volcanic sequence consists of approximately 1700 m of high TiO 2 (4-6.5%) picrite basalts, covered by rhyolitic ignimbrites and lavas, with an average thickness of 300 m, which discontinuously extend over an area of nearly 13,500 km 2 (ca. 3600 km 3). Petrogenetic modelling, using rock and mineral chemical data and phase equilibria calculations by PELE and MELTS, indicates that: 1) picrite basalts could generate rhyolitic, sometimes peralkaline, residual melts with persistently high titanium contents (TiO 2 0.4-1.1%; Fluorine 0.2-0.3%; H 2O 2-3%; density ca. 2.4) corresponding to liquid fractions 9-16%; 2) closed system fractional crystallisation processes developed at 0.1-0.3 GPa pressure and 1390-750 °C temperature ranges, under QFM fO 2 conditions; 3) the highest crystallisation rate - involving 10-13% of Fe-Ti oxide removal - in the temperature range 1070-950 °C, represents a transitory (short-lived) fractionation stage, which results in the absence of erupted silica intermediate products (Daly gap). The eruption of low aspect ratio fluorine-rich rhyolitic ignimbrites and lavas capping the basic volcanics implies a rapid change from open- to closed-system tectono-magmatic conditions, which favoured the trapping of parental picrite basalts and their fractionation in upwardly zoned magma chambers. This evolution resulted from the onset of continental rifting, which was accompanied by normal faulting and block tilting, and the formation of shallow - N-S elongated - fissural chambers parallel to the future Afar Escarpment. The eruption of large volumes of rhyolitic

Two types of gabbroic xenoliths from rhyolite dominated Niijima volcano, northern part of Izu-Bonin arc: petrological and geochemical constraints

Directory of Open Access Journals (Sweden)

Arakawa Yoji

2017-03-01

Full Text Available We examined the petrography, petrology, and geochemistry of two types of gabbroic xenoliths (A- and B-type xenoliths in olivine basalt and biotite rhyolite units among the dominantly rhyolitic rocks in Niijima volcano, northern Izu-Bonin volcanic arc, central Japan. A-type gabbroic xenoliths consisting of plagioclase, clinopyroxene, and orthopyroxene with an adcumulate texture were found in both olivine basalt and biotite rhyolite units, and B-type gabbroic xenoliths consisting of plagioclase and amphibole with an orthocumulate texture were found only in biotite rhyolite units. Geothermal- and barometricmodelling based on mineral chemistry indicated that the A-type gabbro formed at higher temperatures (899–955°C and pressures (3.6–5.9 kbar than the B-type gabbro (687–824°C and 0.8–3.6 kbar. These findings and whole-rock chemistry suggest different parental magmas for the two types of gabbro. The A-type gabbro was likely formed from basaltic magma, whereas the B-type gabbro was likely formed from an intermediate (andesitic magma. The gabbroic xenoliths in erupted products at Niijima volcano indicate the presence of mafic to intermediate cumulate bodies of different origins at relatively shallower levels beneath the dominantly rhyolitic volcano.

Oxygen isotope partitioning between rhyolitic glass/melt and CO2: An experimental study at 550-950 degrees C and 1 bar

International Nuclear Information System (INIS)

Palin, J.M.; Epstein, S.; Stolper, E.M.

1996-01-01

Oxygen isotope partitioning between gaseous CO 2 and a natural rhyolitic glass and melt (77.7 wt% SiO 2 , 0.16 wt% H 2 O total ) has been measured at 550-950 degrees C and approximately 1 bar. Equilibrium oxygen isotope fractionation factors (α CO2-rhyolite = ( 18 O/ 16 O) rhyolite ) determined in exchange experiments of 100-255 day duration. These values agree well with predictions based on experimentally determined oxygen isotope fractionation factors for CO 2 -silica glass and CO 2 -albitic glass/melt, if the rhyolitic glass is taken to be a simple mixture of normative silica and alkali feldspar components. The results indicate that oxygen isotope partitioning in felsic glasses and melts can be modeled by linear combinations of endmember silicate constituents. Rates of oxygen isotope exchange observed in the partitioning experiments are consistent with control by diffusion of molecular H 2 O dissolved in the glass/melt and are three orders of magnitude faster than predicted for rate control solely by diffusion of dissolved molecular CO 2 under the experimental conditions. Additional experiments using untreated and dehydrated (0.09 wt% H 2 O total ) rhyolitic glass quantatively support these interpretations. We conclude that diffusive oxygen isotope exchange in rhyolitic glass/melt, and probably other polymerized silicate materials, it controlled by the concentrations and diffusivities of dissolved oxygen-bearing volatile species rather than diffusion of network oxygen under all but the most volatile-poor conditions. 25 refs., 6 figs., 1 tab

How deep, how hot: comparing pressure and temperature estimates from amphibole and rhyolite-MELTS thermobarometry

Science.gov (United States)

Pamukcu, A. S.; Gualda, G. A.

2013-12-01

Accurately constraining the pressure and temperature of magma residence is problematic, but it is key to understanding the structure and evolution of magmatic systems. Various thermometers exist (Fe-Ti oxides, Ti-in-zircon, Zr-in-sphene, etc.), but there are fewer barometers that can be applied to volcanic rocks. Most barometers capitalize on amphibole, a relatively common mineral whose composition is sensitive to pressure and temperature changes. Glass composition is a function of pressure for magmas saturated in quartz and feldspar, and a new thermobarometer based on rhyolite-MELTS simulations using glass (matrix glass and crystal-hosted glass inclusions) compositions has been recently proposed. We compare results from amphibole and matrix glass thermobarometry. We focus on outflow high-silica rhyolite pumice from the Peach Spring Tuff (CA-NV-AZ, USA), which are characterized by sanidine+plagioclase×quartz+amphibole+sphene in a high-silica rhyolite glass matrix. Compositional variations in amphibole are slight and described by edenite and Ti-Tschermak substitution, with little Al-Tschermak substitution, suggesting small changes in temperature but not in pressure. Plagioclase compositions are also nearly homogeneous. Thus, we expect thermobarometry results to cluster around a single pressure and temperature, making these samples excellent candidates for comparing thermobarometers. Amphibole×plagioclase thermobarometry reveals: - Amphibole-plagioclase: results vary widely depending on the calibration (e.g. 150-420 MPa, 520-730 °C); combined Anderson & Smith (1995) barometer with Holland & Blundy (1990) thermometer is most consistent, suggesting crystallization at 230 MPa, 680 °C. - Amphibole-only: calibrations give significantly different results (75-115 MPa, 770-960 °C [Ridolfi et al. 2010]; 400-950 MPa, 800-950°C [Ridolfi & Renzulli 2012]). Results suggest the recent re-calibration is particularly unreliable for these rocks, and the earlier calibration is

Tertiary volcanic rocks and uranium in the Thomas Range and northern Drum Mountains, Juab County, Utah

Science.gov (United States)

Lindsey, David A.

1982-01-01

(?) Formation was erupted 30-31 m.y. ago from an unknown source. Mineralization probably did not occur during the rhyolitic stage of volcanism. The last stage of volcanism was contemporaneous with basin-and-range faulting and was characterized by explosive eruption of ash and pumice, forming stratified tuff, and by quiet eruption of alkali rhyolite as viscous flows and domes. The first episode of alkali rhyolite volcanism deposited the beryllium tuff and porphyritic rhyolite members of the Spor Mountain Formation 21 m.y. ago. After a period of block faulting, the stratified tuff and alkali rhyolite of the Topaz Mountain Rhyolite were erupted 6-7 m.y. ago along faults and fault intersections. Erosion of Spor Mountain, as well as explosive eruptions through dolomite, provided abundant dolomite detritus to the beryllium tuff member. The alkali rhyolite of both formations is fluorine rich, as is evident from abundant topaz, and contains anomalous amounts of lithophile metals. Alkali rhyolite volcanism was accompanied by lithophile metal mineralization which deposited fluorite, beryllium, and uranium. The structure of the area is dominated by the Thomas caldera and the younger Dugway Valley cauldron, which is nested within the Thomas caldera; the Thomas caldera is surrounded by a rim of Paleozoic rocks at Spor Mountain and Paleozoic to Precambrian rocks in the Drum Mountains. The Joy fault and Dell fault system mark the ring-fracture zone of the Thomas caldera. These structural features began to form about 39 m.y. ago during eruption of the Mt. Laird Tuff and caldera subsidence. The Dugway Valley cauldron sank along a series of steplike normal faults southeast of Topaz Mountain in response to collapse of the magma chamber of the Joy Tuff. Caldera structure was modified by block faulting between 21 and 7 m.y. ago, the time of widespread extensional faulting in the Basin and Range Province. Vents erupted alkali rhyolite 6-7 m.y. ago along basin-and-range faults.

Possible two-stage /sup 87/Sr evolution in the Stockdale Rhyolite

Energy Technology Data Exchange (ETDEWEB)

Compston, W.; McDougall, I. (Australian National Univ., Canberra. Research School of Earth Sciences); Wyborn, D. (Department of Minerals and Energy, Canberra (Australia). Bureau of Mineral Resources)

1982-12-01

The Rb-Sr total-rock data for the Stockdale Rhyolite, of significance for the Palaeozoic time scale, are more scattered about a single-stage isochron than expected from experimental error. Two-stage /sup 87/Sr evolution for several of the samples is explored to explain this, as an alternative to variation in the initial /sup 87/Sr//sup 86/Sr which is customarily used in single-stage dating models. The deletion of certain samples having very high Rb/Sr removes most of the excess scatter and leads to an estimate of 430 +- 7 m.y. for the age of extrusion. There is a younger alignment of Rb-Sr data within each sampling site at 412 +- 7 m.y. We suggest that the Stockdale Rhyolite is at least 430 m.y. old, that its original range in Rb/Sr was smaller than now observed, and that it experienced a net loss in Sr during later hydrothermal alteration at ca. 412 m.y.

Emplacement model of obsidian-rhyolite magma deduced from complete internal section of the Akaishiyama lava, Shirataki, northern Hokkaido, Japan

Science.gov (United States)

Wada, K.; Sano, K.

2016-12-01

Simultaneously explosive and effusive eruptions of silicic magmas has shed light on the vesiculation and outgassing history of ascending magmas in the conduit and emplacement model of obsidian-rhyolite lavas (Castro et al., 2014; Shipper et al, 2013). As well as the knowledge of newly erupted products such as 2008-2009 Chaitén and 2011-2012 Cordón Caule eruptions, field and micro-textural evidences of well-exposed internal structure of obsidian-rhyolite lava leads to reveal eruption processes of silicic magmas. The Shirataki monogenetic volcano field, 2.2 million year age, northern Hokkaido, Japan, contains many outcrops of obsidian and vesiculated rhyolite zones (SiO2=76.7-77.4 wt.%). Among their outcrops, Akaishiyama lava shows good exposures of internal sections from the top to the bottom along the Kyukasawa valley with thickness of about 190 meters, showing the symmetrical structure comprising a upper clastic zone (UCZ; 5m thick), an upper dense obsidian zone (UDO; 15m), an upper banded obsidian zone (UBO; 70-80m), a central rhyolite zone (CR; 65m), a lower banded obsidian zone (LBO; 15m), a lower dense obsidian zone (LDO; 20m), and a lower clastic zone (LCZ; 3m). The upper banded obsidian zone is characterized by existence of spherulite concentration layers with tuffisite veins and rhyolite enclaves. Spherulites consisting of albite, cristobalaite and obsidian glass, are clustered in the dense obsidian. Tuffisite veins show brecciated obsidians in tuffaceous matrix, showing an outgassing path during the emplacement of obsidian lava. Perpendicular dip of spherulite parallel rows indicates the banded zone itself was the domain of vent area. From the observation of these occurrences in the internal section and rock texture, we show the qualitative formation model of Shirataki obsidian-rhyolite lava.

Miocene volcanism in the Oaş-Gutâi Volcanic Zone, Eastern Carpathians, Romania: Relationship to geodynamic processes in the Transcarpathian Basin

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Kovacs, Marinel; Seghedi, Ioan; Yamamoto, Masatsugu; Fülöp, Alexandrina; Pécskay, Zoltán; Jurje, Maria

2017-12-01

We present the first comprehensive study of Miocene volcanic rocks of the Oaş-Gutâi Volcanic Zone (OGVZ), Romania, which are exposed in the eastern Transcarpathian Basin (TB), within the Eastern Alpine-Western Carpathian-Northern Pannonian (ALCAPA) block. Collision between the ALCAPA block and Europe at 18-16 Ma produced the Carpathian fold-and-thrust belt. This was followed by clockwise rotation and an extensional regime forming core complexes of the separated TB fragment. Based on petrographic and geochemical data, including Srsbnd Nd isotopic compositions and Ksbnd Ar ages, we distinguish three types of volcanic activity in the OGVZ: (1) early Miocene felsic volcanism that produced caldera-related ignimbrites in the Gutâi Mountains (15.4-14.8 Ma); (2) widespread middle-late Miocene intermediate/andesitic volcanism (13.4-7.0 Ma); and (3) minor late Miocene andesitic/rhyolitic volcanism comprising the Oraşu Nou rhyolitic volcano and several andesitic-dacitic domes in the Oaş Mountains (11.3-9.5 Ma). We show that magma evolution in the OGVZ was controlled by assimilation-fractional crystallization and magma-mixing processes within an interconnected multi-level crustal magmatic reservoir. The evolution of volcanic activity within the OGVZ was controlled by the geodynamics of the Transcarpathian Basin. The early felsic and late intermediate Miocene magmas were emplaced in a post-collisional setting and were derived from a mantle source region that was modified by subduction components (dominantly sediment melts) and lower crust. The style of volcanism within the eastern TB system exhibits spatial variations, with andesitic composite volcanoes (Gutâi Mountains) observed at the margins, and isolated andesitic-rhyolitic monogenetic volcanoes (Oaş Mountains) in the center of the basin.

Fluvial sedimentology of a major uranium-bearing sandstone - A study of the Westwater Canyon member of the Morrison Formation, San Juan Basin, New Mexico

International Nuclear Information System (INIS)

Turner-Peterson, C.E.

1986-01-01

The Westwater Canyon Member of the Morrison Formation, the main ore-bearing sandstone in the San Juan basin, consists of a sequence of vertically stacked braided stream deposits. Three fluvial units within the sequence can be delineated in the basin. Volcanic pebbles are abundant in the middle fluvial unit, in a zone that forms a crude time line. A pronounced thickening of sandstone in the Westwater Canyon Member north of Gallup, once believed to be the apex of a large alluvial fan, is now thought to merely reflect a greater accumulation of sediment in response to downwarping of the basin in that area. Provenance studies suggest that highlands that contributed detritus to Westwater Canyon streams were located several hundred kilometers to the west and southwest of the San Juan basin, and thus fan apices would also have been several hundred kilometers upstream. The fluvial units recognized in the basin may well be coalesced distal fan deposits, but are probably best interpreted as vertically stacked braided steam sequences. Facies changes in fine-grained interbeds of the Westwater Canyon probably have greater significance in terms of localizing ore than any special attribute of the fluvial sandstones themselves. Uranium ore generally occurs in sandstones that are interbedded with greenish-gray lacustrine mudstones. Pore waters that were expelled from these mudstones are thought to have been the source of the pore-filling organic matter (humate) associated with primary uranium ore in nearby sandstones

Assessment of undiscovered oil and gas resources in the Uteland Butte Member of the Eocene Green River Formation, Uinta Basin, Utah

Science.gov (United States)

Johnson, Ronald C.; Birdwell, Justin E.; Mercier, Tracey J.; Brownfield, Michael E.; Charpentier, Ronald R.; Klett, Timothy R.; Leathers, Heidi M.; Schenk, Christopher J.; Tennyson, Marilyn E.

2015-09-03

Using a geology-based assessment methodology, the U.S. Geological Survey estimated mean undiscovered resources of 214 million barrels of oil, 329 billion cubic feet of associated/dissolved natural gas, and 14 million barrels of natural gas liquids in the informal Uteland Butte member of the Green River Formation, Uinta Basin, Utah.

Tectonic-sedimentary evolution of foreland basins: U-Pb dating of the discharge that would have originated the piggy-back basin of Rodeo-Iglesias, San Juan-Argentina; Evolucao tectono-sedimentar de bacias de antepais: datacao U-Pb do corrimento que teria originado a bacia de piggy-back de Rodeo-Iglesias, San Juan-Argentina

Energy Technology Data Exchange (ETDEWEB)

Santos, Romulo Duarte Moreira dos; Hauser, Natalia; Matteini, Massimo; Pimentel, Marcio Martins [Universidade de Brasilia (UnB), DF (Brazil). Instituto de Geociencias. Laboratorio de de Estudos Geocronologicos, Geodinamicos e Ambientais; Limarino, Oscar; Marensi, Sergio; Ciccioli, Patricia; Alonso, Susana, E-mail: romulodms@gmail.com [Departamento de Ciencias Geologicas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina)

2015-07-01

Between the 28 ° and 31 ° LS parallels of the Argentinean west, in the province of San Juan, foreland basins originated by the subhorizontal subduction of oceanic crust as a result of the Andean orogeny in the late Oligocene emerges. The Bermejo basin and Rodeo-Iglesias piggy-back basin would be associated with the progressive development of landslides, backscatter and minor faults, and basin fragmentation. Two samples of volcanic rocks, R-1 (rhyolitic dome) and R-3 (fall deposit) of the Rodeo-Iglesias basin, had ages of 8.2 ± 0.11 Ma and 8.7 ± 0.24 Ma. At the same time, the age of the (R-1) made it possible to infer quantitatively the age of the first cavalcade that occurred approximately 8.2 ± 0.11 Ma. From the data obtained in the Rodeo-Iglesias basin both volcanism and the first cavalcade could have been synchronous.

Composition and origin of rhyolite melt intersected by drilling in the Krafla geothermal field, Iceland

Science.gov (United States)

Zierenberg, R.A.; Schiffman, P.; Barfod, G.H.; Lesher, C.E.; Marks, N.E.; Lowenstern, Jacob B.; Mortensen, A.K.; Pope, E.C.; Bird, D.K.; Reed, M.H.; Friðleifsson, G.O.; Elders, W.A.

2013-01-01

The Iceland Deep Drilling Project Well 1 was designed as a 4- to 5-km-deep exploration well with the goal of intercepting supercritical hydrothermal fluids in the Krafla geothermal field, Iceland. The well unexpectedly drilled into a high-silica (76.5 % SiO2) rhyolite melt at approximately 2.1 km. Some of the melt vesiculated while extruding into the drill hole, but most of the recovered cuttings are quenched sparsely phyric, vesicle-poor glass. The phenocryst assemblage is comprised of titanomagnetite, plagioclase, augite, and pigeonite. Compositional zoning in plagioclase and exsolution lamellae in augite and pigeonite record changing crystallization conditions as the melt migrated to its present depth of emplacement. The in situ temperature of the melt is estimated to be between 850 and 920 °C based on two-pyroxene geothermometry and modeling of the crystallization sequence. Volatile content of the glass indicated partial degassing at an in situ pressure that is above hydrostatic (~16 MPa) and below lithostatic (~55 MPa). The major element and minor element composition of the melt are consistent with an origin by partial melting of hydrothermally altered basaltic crust at depth, similar to rhyolite erupted within the Krafla Caldera. Chondrite-normalized REE concentrations show strong light REE enrichment and relative flat patterns with negative Eu anomaly. Strontium isotope values (0.70328) are consistent with mantle-derived melt, but oxygen and hydrogen isotope values are depleted (3.1 and −118 ‰, respectively) relative to mantle values. The hydrogen isotope values overlap those of hydrothermal epidote from rocks altered by the meteoric-water-recharged Krafla geothermal system. The rhyolite melt was emplaced into and has reacted with a felsic intrusive suite that has nearly identical composition. The felsite is composed of quartz, alkali feldspar, plagioclase, titanomagnetite, and augite. Emplacement of the rhyolite magma has resulted in partial melting of

Stratigraphy, geochronology and regional tectonic setting of the Late Cretaceous (ca. 82-70 Ma) Cabullona basin, Sonora, Mexico

Science.gov (United States)

González-León, Carlos M.; Solari, Luigi A.; Madhavaraju, Jayagopal

2017-12-01

magmatic arc that located to the west of the basin, and to a tectonic shortening that occurred in northern Sonora during Late Cretaceous time. In the older columns of the Cabullona Group and in columns of the northern part, the early arc had a distal influence during sedimentation as shown by interbedded ash fall tuffs and minor rhyolitic flows, but sections in the southern part of the basin record more abundant rhyolitic ash-fall tuffs and flows indicating the arc proximity. An important regional flare-up of the arc at ca. 74 Ma is recorded by the Ejido Ruiz Cortines column, while the upper part of the Cabullona Group was interdigitating with rhyolitic rocks by 70 Ma. The Cabullona basin started to form during the shortening event whose age is constrained between ca. 93 and 76 Ma according to U-Pb ages of the syntectonic Cocóspera Formation of northern Sonora and from Laramide arc rocks that overlie it. Ages and correlation of the Cocóspera and the Altar formations may indicate that a Laramide tectonic front extended from north-central Sonora to the Caborca region and whose trace may correspond to a westward extension of the San Antonio fault.

Insights into hydrologic and hydrochemical processes based on concentration-discharge and end-member mixing analyses in the mid-Merced River Basin, Sierra Nevada, California

Science.gov (United States)

Liu, Fengjing; Conklin, Martha H.; Shaw, Glenn D.

2017-01-01

Both concentration-discharge relation and end-member mixing analysis were explored to elucidate the connectivity of hydrologic and hydrochemical processes using chemical data collected during 2006-2008 at Happy Isles (468 km2), Pohono Bridge (833 km2), and Briceburg (1873 km2) in the snowmelt-fed mid-Merced River basin, augmented by chemical data collected by the USGS during 1990-2014 at Happy Isles. Concentration-discharge (C-Q) in streamflow was dominated by a well-defined power law relation, with the magnitude of exponent (0.02-0.6) and R2 values (p lower on rising than falling limbs. Concentrations of conservative solutes in streamflow resulted from mixing of two end-members at Happy Isles and Pohono Bridge and three at Briceburg, with relatively constant solute concentrations in end-members. The fractional contribution of groundwater was higher on rising than falling limbs at all basin scales. The relationship between the fractional contributions of subsurface flow and groundwater and streamflow (F-Q) followed the same relation as C-Q as a result of end-member mixing. The F-Q relation was used as a simple model to simulate subsurface flow and groundwater discharges to Happy Isles from 1990 to 2014 and was successfully validated by solute concentrations measured by the USGS. It was also demonstrated that the consistency of F-Q and C-Q relations is applicable to other catchments where end-members and the C-Q relationships are well defined, suggesting hydrologic and hydrochemical processes are strongly coupled and mutually predictable. Combining concentration-discharge and end-member mixing analyses could be used as a diagnostic tool to understand streamflow generation and hydrochemical controls in catchment hydrologic studies.

Long-lived melting of ancient lower crust of the North China Craton in response to paleo-Pacific plate subduction, recorded by adakitic rhyolite

Science.gov (United States)

Wang, Chao; Song, Shuguang; Niu, Yaoling; Allen, Mark B.; Su, Li; Wei, Chunjing; Zhang, Guibin; Fu, Bin

2017-11-01

Magmatism in eastern China in response to paleo-Pacific plate subduction during the Mesozoic was complex, and it is unclear how and when exactly the magmas formed via thinning and partial destruction of the continental lithosphere. To better understand this magmatism, we report the results of a geochronological and geochemical study of Early Cretaceous adakitic rhyolite (erupted at 125.4 ± 2.2 Ma) in the Xintaimen area within the eastern North China Craton (NCC). In situ zircon U-Pb dating shows that this adakitic rhyolite records a long ( 70 Myrs) and complicated period of magmatism with concordant 206Pb/238U ages from 193 Ma to 117 Ma. The enriched bulk rock Sr-Nd isotopic compositions of the Xintaimen adakitic rhyolite, as well as the enriched zircon Hf and O isotopic compositions, indicate that the magmas parental to the adakitic rhyolite were derived from partial melting of the Paleoproterozoic mafic lower crust, heated by mafic melts derived from the mantle during the paleo-Pacific plate subduction. A minor older basement component is indicated by the presence of captured Neoarchean to Early Paleoproterozoic zircons. The Mesozoic zircons have restricted Hf and O isotopic compositions irrespective of their ages, suggesting that they formed from similar sources at similar melting conditions. The Xintaimen adakitic rhyolite offers an independent line of evidence that the ancient lower crust of eastern China underwent a long period ( 70 Myrs) of destruction, melting or remelting, from 193 to 120 Ma, related to the subduction of the paleo-Pacific plate beneath eastern China.

The permeability evolution of tuffisites and outgassing from dense rhyolitic magma

Science.gov (United States)

Heap, M. J.; Tuffen, H.; Wadsworth, F. B.; Reuschlé, T.; Castro, J. M.; Schipper, C. I.

2017-12-01

Recent observations of rhyolitic lava effusion from eruptions in Chile indicate that simultaneous pyroclastic venting facilitates outgassing. Venting from conduit-plugging lava domes is pulsatory and occurs through shallow fracture networks that deliver pyroclastic debris and exsolved gases to the surface. However, these fractures become blocked as the particulate fracture infill sinters viscously, thus drastically reducing permeability. Tuffisites, fossilized debris-filled fractures of this venting process, are abundant in pyroclastic material ejected during hybrid explosive-effusive activity. Dense tuffisite-hosting obsidian bombs ejected from Volcán Chaitén (Chile) in 2008 afford an opportunity to better understand the permeability evolution of tuffisites within low-permeability conduit plugs, wherein gas mobility is reliant upon fracture pathways. We use laboratory measurements of the permeability and porosity of tuffisites that preserve different degrees of sintering, combined with a grainsize-based sintering model and constraints on pressure-time paths from H2O diffusion, to place first-order constraints on tuffisite permeability evolution. Inferred timescales of sintering-driven tuffisite compaction and permeability loss, spanning minutes to hours, coincide with observed vent pulsations during hybrid rhyolitic activity and, more broadly, timescales of pressurization accompanying silicic lava dome extrusion. We therefore conclude that sintering exerts a first-order control on fracture-assisted outgassing from low-permeability, conduit-plugging silicic magma.

Petrophysical characterization of the Dolomitic Member of the Boñar Formation (Upper Cretaceous; Duero Basin, Spain) as a potential CO2 reservoir

Energy Technology Data Exchange (ETDEWEB)

Suarez-Gonzalez, A.; Kovacs, C.; Herrero-Hernandez, A.; Gomez-Fernandez, F.

2016-07-01

Boñar Formation (Upper Cretaceous) is a mainly carbonate succession, which outcrops in the North of Duero Basin (Spain). According to the existing data, the Dolomitic Member of this formation appears to be the most suitable for geological storage of CO2. The main objective of this study is to find evidence to support, clarify and specify –at an initial level– the potential of the Dolomitic Member of the Boñar Formation as a geological reservoir. The study covers density, porosity and permeability tests on samples obtained from the outcrop of the succession near the village of Boñar (León). According to the analysis and interpretation of the mentioned petrophysical properties, the porosity of the Dolomitic Member is within the acceptable range for CO2 geological storage, but the permeability values are far too low. This minimizes the possibilities of the Dolomitic Member –and probably of the whole Boñar Formation– to become an appropriate CO2 reservoir. (Author)

Paleodepositional environment and age of Kanawa Member of Pindiga Formation, Gongola Sub-basin, Northern Benue Trough, NE Nigeria: Sedimentological and palynological approach

Science.gov (United States)

Aliyu, Abdulkarim H.; Mamman, Y. D.; Abubakar, M. B.; Sarki Yandoka, Babangida M.; Jitong, John Shirputda; Shettima, Bukar

2017-10-01

Sedimentogical and palynological investigations of the Kanawa Member of Pindiga Formation in the Gongola Sub-basin, Northern Benue Trough, NE Nigeria were carried out in order to determine the paleoenvironment and age of the sediments. Three main lithofacies were identified from the measured sedimentary log section, namely; the wave rippled sandstones, the limestones (with ammonites, bivalves and gastropods) and the clay-shale. The facies were interpreted to have been deposited in a marine environment. Based on palynological studies, Kanawa Member consists of two palynozones, namely; Cretacaeiporites scabratus and Triorites africaensis. The Triorites africaensis zone is characterized by species of T. africaensis, Gnetaceaepollenites sp. 1, Cretacaeiporites polygonalis, Monosulcites sp., Cretacaeiporites scabratus, Elaterocolpites castelainii and is dated Late Cenomanian whilst the Cretacaeiporites scabratus zone is characterized by the dominance of C. scabratus, C. mulleri and Tricolporopollenites sp and is dated Early Turonian. The Kanawa Member is therefore, dated Late Cenomanian to early Turonian.

Late Mesozoic basin and range tectonics and related magmatism in Southeast China

Directory of Open Access Journals (Sweden)

Dezi Wang

2012-03-01

Full Text Available During the Late Mesozoic Middle Jurassic–Late Cretaceous, basin and range tectonics and associated magmatism representative of an extensional tectonic setting was widespread in southeastern China as a result of Pacific Plate subduction. Basin tectonics consists of post-orogenic (Type I and intra-continental extensional basins (Type II. Type I basins developed in the piedmont and intraland during the Late Triassic to Early Jurassic, in which coarse-grained terrestrial clastic sediments were deposited. Type II basins formed during intra-continental crustal thinning and were characterized by the development of grabens and half-grabens. Graben basins were mainly generated during the Middle Jurassic and were associated with bimodal volcanism. Sediments in half-grabens are intercalated with rhyolitic tuffs and lavas and are Early Cretaceous in age with a dominance of Late Cretaceous–Paleogene red beds. Ranges are composed of granitoids and bimodal volcanic rocks, A-type granites and dome-type metamorphic core complexes. The authors analyzed lithological, geochemical and geochronological features of the Late Mesozoic igneous rock assemblages and proposed some geodynamical constraints on forming the basin and range tectonics of South China. A comparison of the similarities and differences of basin and range tectonics between the eastern and western shores of the Pacific is made, and the geodynamical evolution model of the Southeast China Block during Late Mesozoic is discussed. Studied results suggest that the basin and range terrane within South China developed on a pre-Mesozoic folded belt was derived from a polyphase tectonic evolution mainly constrained by subduction of the western Pacific Plate since the Late Mesozoic, leading to formation of various magmatism in a back-arc extensional setting. Its geodynamic mechanism can compare with that of basin and range tectonics in the eastern shore of the Pacific. Differences of basin and range

The timing of compositionally-zoned magma reservoirs and mafic 'priming' weeks before the 1912 Novarupta-Katmai rhyolite eruption

Science.gov (United States)

Singer, Brad S.; Costa, Fidel; Herrin, Jason S.; Hildreth, Wes; Fierstein, Judith

2016-01-01

The June 6, 1912 eruption of more than 13 km3 of dense rock equivalent (DRE) magma at Novarupta vent, Alaska was the largest of the 20th century. It ejected >7 km3 of rhyolite, ~1.3 km3 of andesite and ~4.6 km3 of dacite. Early ideas about the origin of pyroclastic flows and magmatic differentiation (e.g., compositional zonation of reservoirs) were shaped by this eruption. Despite being well studied, the timing of events that led to the chemically and mineralogically zoned magma reservoir remain poorly known. Here we provide new insights using the textures and chemical compositions of plagioclase and orthopyroxene crystals and by reevaluating previous U-Th isotope data. Compositional zoning of the magma reservoir likely developed a few thousand years before the eruption by several additions of mafic magma below an extant silicic reservoir. Melt compositions calculated from Sr contents in plagioclase fill the compositional gap between 68 and 76% SiO2 in whole pumice clasts, consistent with uninterrupted crystal growth from a continuum of liquids. Thus, our findings support a general model in which large volumes of crystal-poor rhyolite are related to intermediate magmas through gradual separation of melt from crystal-rich mush. The rhyolite is incubated by, but not mixed with, episodic recharge pulses of mafic magma that interact thermochemically with the mush and intermediate magmas. Hot, Mg-, Ca-, and Al-rich mafic magma intruded into, and mixed with, deeper parts of the reservoir (andesite and dacite) multiple times. Modeling the relaxation of the Fe-Mg concentrations in orthopyroxene and Mg in plagioclase rims indicates that the final recharge event occurred just weeks prior to the eruption. Rapid addition of mass, volatiles, and heat from the recharge magma, perhaps aided by partial melting of cumulate mush below the andesite and dacite, pressurized the reservoir and likely propelled a ~10 km lateral dike that allowed the overlying rhyolite to reach the surface.

Subaqueous rhyolite block lavas in the Miocene Ushikiri Formation, Shimane Peninsula, SW Japan

Science.gov (United States)

Kano, Kazuhiko; Takeuchi, Keiji; Yamamoto, Takahiro; Hoshizumi, Hideo

1991-06-01

A rhyolite mass of the Miocene Ushikiri Formation in the western part of the Shimane Peninsula, SW Japan, is a small subaqueous edifice about 600 m high and 4 km wide, formed at water depths between 200 and 1000 m. It consists mainly of three relatively flat, lava-flow units 50-300 m in maximum thickness, each of which includes lobes and their polyhedral fragments. The lava lobes are poorly to well vesiculated, glassy to microcrystalline and flow-banded and -folded. Compared with mafic pillows, they are large, having thick, quenched and brecciated, glassy crusts because of their high viscosity, surface tension and thermal conductivity. Their surfaces disintegrate into polyhedral fragments and grade into massive volcanic breccia. The massive volcanic breccia composed of the lobe fragments is poorly sorted and covered with stratified volcanic breccia of the same rock type. The rhyolite lavas commonly bifurcate in a manner similar to mafic pillow lavas. However, they are highly silicic with 1-5 vol.% phenocrysts and have elongated vesicles and flow-folds, implying that they were visco-plastic during flowage. Their surface features are similar to those of subaerial block lava. With respect to rheological and morphological features, they are subaqueous equivalents of block lava.

Exceptional mobility of an advancing rhyolitic obsidian flow at Cordón Caulle volcano in Chile.

Science.gov (United States)

Tuffen, Hugh; James, Mike R; Castro, Jonathan M; Schipper, C Ian

2013-01-01

The emplacement mechanisms of rhyolitic lava flows are enigmatic and, despite high lava viscosities and low inferred effusion rates, can result in remarkably, laterally extensive (>30 km) flow fields. Here we present the first observations of an active, extensive rhyolitic lava flow field from the 2011-2012 eruption at Cordón Caulle, Chile. We combine high-resolution four-dimensional flow front models, created using automated photo reconstruction techniques, with sequential satellite imagery. Late-stage evolution greatly extended the compound lava flow field, with localized extrusion from stalled, ~35 m-thick flow margins creating >80 breakout lobes. In January 2013, flow front advance continued ~3.6 km from the vent, despite detectable lava supply ceasing 6-8 months earlier. This illustrates how efficient thermal insulation by the lava carapace promotes prolonged within-flow horizontal lava transport, boosting the extent of the flow. The unexpected similarities with compound basaltic lava flow fields point towards a unifying model of lava emplacement.

Facies architecture of basin-margin units in time and space: Lower to Middle Miocene Sivas Basin, Turkey

Science.gov (United States)

Çiner, A.; Kosun, E.

2003-04-01

The Miocene Sivas Basin is located within a collision zone, forming one of the largest basins in Central Turkey that developed unconformably on a foundered Paleozoic-Mesozoic basement and Eocene-Oligocene deposits. The time and space relationships of sedimentary environments and depositional evolution of Lower to Middle Miocene rocks exposed between Zara and Hafik towns is studied. A 4 km thick continuous section is subdivided into the Agilkaya and Egribucak Formations. Each formation shows an overall fining upward trend and contains three members. Although a complete section is present at the western part (near Hafik) of the basin, to the east the uppermost two members (near Zara) are absent. The lower members of both formations are composed of fluvial sheet-sandstone and red mudstone that migrate laterally on a flood basin within a semi-arid fan system. In the Agilkaya Formation that crops out near Zara, alluvial fans composed of red-pink volcanic pebbles are also present. The middle members are composed of bedded to massive gypsum and red-green mudstone of a coastal and/or continental sabkha environment. While the massive gypsum beds reach several 10’s of m in Hafik area, near Zara, they are only few m thick and alternate with green mudstones. In Hafik, bedded gypsums are intercalated with lagoonal dolomitic limestone and bituminous shale in the Agilkaya Formation and with fluvial red-pink sandstone-red mudstone in the Egribucak Formation. The upper members are made up of fossiliferous mudstone and discontinuous sandy limestone beds with gutter casts, HCS, and 3-D ripples. They indicate storm-induced sedimentation in a shallow marine setting. The disorganized accumulations of ostreid and cerithiid shells, interpreted as coquina bars, are the products of storm generated reworking processes in brackish environments. Rapid vertical and horizontal facies changes and the facies associations in both formations reflect the locally subsiding nature of this molassic

Permian A-type rhyolites of the Muráň Nappe, Inner Western Carpathians, Slovakia: in-situ zircon U-Pb SIMS ages and tectonic setting

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Ondrejka, Martin; Li, Xian-Hua; Vojtko, Rastislav; Putis, Marian; Uher, Pavel; Sobocký, Tomas

2018-04-01

Three representative A-type rhyolitic rock samples from the Muráň Nappe of the inferred Silicic Unit of the Inner Western Carpathians (Slovakia) were dated using the high-precision SIMS U-Pb isotope technique on zircons. The geochronological data presented in this paper is the first in-situ isotopic dating of these volcanic rocks. Oscillatory zoned zircon crystals mostly revealed concordant Permian (Guadalupian) ages: 266.6 ± 2.4 Ma in Tisovec-Rejkovo (TIS-1), 263.3 ± 1.9 Ma in Telgárt-Gregová Hill (TEL-1) and 269.5 ± 1.8 Ma in Veľká Stožka-Dudlavka (SD-2) rhyolites. The results indicate that the formation of A-type rhyolites and their plutonic equivalents are connected to magmatic activity during the Permian extensional tectonics and most likely related to the Pangea supercontinent break-up.

Drilling a ';super-volcano': volcanology of the proximal rhyolitic volcanic succession in the HOTSPOT deep drill hole, Idaho, Yellowstone hot-spot track

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Knott, T.; Branney, M. J.; Christiansen, E. H.; Reichow, M. K.; McCurry, M. O.; Shervais, J. W.

2013-12-01

Project HOTSPOT seeks to understand the bimodal volcanism in the Yellowstone-Snake River large igneous province, including the magma generation and eruption history. The 1.9 km-deep Kimberly well in southern Idaho, USA, reveals a proximal mid-Miocene rhyolitic and basaltic volcanic succession marginal to the postulated Twin Falls eruptive centre. Three rhyolitic eruption-units (each we interpret to record a single eruption, based on core descriptions) are separated by basaltic lavas, palaeosols and volcaniclastic sediments, and are being dated by 40Ar-39Ar on plagioclases. Whole-rock and mineral chemical data, from each unit, has been compiled to facilitate correlation with well-studied eruption-units at more distal outcrops, where we have detailed chemical, palaeomagnetic and radiometric characterisation. Results will contribute to frequency and volume calculations for some of the most catastrophic super-eruptions in Earth history. As the volcanism is of Snake River (SR)-type and lacks typical pumice fall deposits and low-moderate grade ignimbrites, interpreting the physical origin of the units can be difficult; many SR-type rheomorphic ignimbrites are flow-banded and resemble lavas, and the distinction between these and true lavas involves interpretation of critical evidence from lower contacts (e.g., distinguishing basal lava autobreccias from peperitic contacts, which can occur at the bases of SR-type lavas and ignimbrites). The lower most eruption-unit, ';Kimberly Rhyolite 1,' is >1323 m thick (base not seen) and suggests ponding in the margin of a caldera. Few vitroclastic textures are preserved, but a rheomorphic ignimbrite origin is inferred by folded fabrics and scattered obsidian chips (2-5 mm in size) within a thick lithoidal zone, which passes sharply upwards into a 39.6 m thick vitrophyre with an autobrecciated top and it is overlain by 18 m (caldera?) lake sediments. However, lithic mesobreccia, that characterise caldera fills elsewhere, are not seen

Sequence stratigraphy, sedimentary systems and petroleum plays in a low-accommodation basin: Middle to upper members of the Lower Jurassic Sangonghe Formation, Central Junggar Basin, Northwestern China

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Feng, Youliang; Jiang, Shu; Wang, Chunfang

2015-06-01

The Lower Jurassic Junggar Basin is a low-accommodation basin in northwestern China. Because of low subsidence rates and a warm, wet climate, deposits of the Central subbasin of the Junggar Basin formed from fluvial, deltaic, shallow lake facies. Sequence stratigraphy and sedimentary systems of the Lower Jurassic members of the Sangonghe Formation (J1s) were evaluated by observing cores, interpreting wireline logs and examining seismic profiles. Two third-order sequences were recognized in the strata. The distribution of the sedimentary systems in the systems tracts shows that tectonic movement, paleorelief, paleoclimate and changes in lake level controlled the architecture of individual sequences. During the development of the lowstand systems tract (LST), the intense structural movement of the basin resulted in a significant fall in the water level in the lake, accompanied by rapid accommodation decrease. Braided rivers and their deltaic systems were also developed in the Central Junggar Basin. Sediments carried by braided rivers were deposited on upward slopes of the paleorelief, and braid-delta fronts were deposited on downward slopes. During the transgressive systems tract (TST), the tectonic movement of the basin was quiescent and the climate was warm and humid. Lake levels rose and accommodation increased quickly, shoal lines moved landward, and shore- to shallow-lake deposits, sublacustrine fans and deep-lake facies were deposited in shallow- to deep-lake environments. During the highstand systems tract (HST), the accommodation no longer increased but sediment supply continued, far exceeding accommodation. HST deposits slowly formed in shallow-lake to meandering river delta-front environments. Relatively low rates of structural subsidence and low accommodation resulted in coarse-grained successions that were fining upward. Deposits were controlled by structural movement and paleorelief within the LST to TST deposits in the Central subbasin. Fine- to medium

Lithostratigraphy of the Cretaceous–Paleocene Nuussuaq Group, Nuussuaq Basin, West Greenland

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Dam, Gregers

2009-12-01

Full Text Available The Nuussuaq Basin is the only exposed Cretaceous–Paleocene sedimentary basin in West Greenland and is one of a complex of linked rift basins stretching from the Labrador Sea to northern Baffin Bay. These basins developed along West Greenland as a result of the opening of the Labrador Sea in Late Mesozoic to Early Cenozoic times. The Nuussuaq Basin is exposed in West Greenland between 69°N and 72°N on Disko, Nuussuaq, Upernivik Ø, Qeqertarsuaq, Itsaku and Svartenhuk Halvø and has also been recorded in a number of shallow and deep wells in the region. The sediments are assigned to the more than 6 km thick Nuussuaq Group (new which underlies the Palaeogene plateau basalts of the West Greenland Basalt Group. The sediment thickness is best estimated from seismic data; in the western part of the area, seismic and magnetic data suggest that the succession is at least 6 km and possibly as much as 10 km thick. The exposed Albian–Paleocene part of the succession testifies to two main episodes of regional rifting and basin development: an EarlyCretaceous and a Late Cretaceous – Early Paleocene episode prior to the start of sea-floor spreading in mid-Paleocene time. This exposed section includes fan delta, fluviodeltaic, shelfal and deepmarine deposits. The Nuussuaq Group is divided into ten formations, most of which have previously been only briefly described, with the exception of their macrofossil content. In ascending stratigraphic order, the formations are: the Kome Formation, the Slibestensfjeldet Formation (new, the Upernivik Næs Formation, the Atane Formation (including four new members – the Skansen, Ravn Kløft, Kingittoq and Qilakitsoq Members – and one new bed, the Itivnera Bed, the Itilli Formation (new, including four new members: the Anariartorfik, Umiivik, Kussinerujuk and Aaffarsuaq Members, the Kangilia Formation (including the revised Annertuneq Conglomerate Member andthe new Oyster–Ammonite Conglomerate Bed, the

Origin and potential geothermal significance of China Hat and other late Pleistocene topaz rhyolite lava domes of the Blackfoot Volcanic Field, SE Idaho

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McCurry, M. O.; Pearson, D. M.; Welhan, J. A.; Kobs-Nawotniak, S. E.; Fisher, M. A.

2014-12-01

The Snake River Plain and neighboring regions are well known for their high heat flow and robust Neogene-Quaternary tectonic and magmatic activity. Interestingly, however, there are comparatively few surficial manifestations of geothermal activity. This study is part of a renewed examination of this region as a possible hidden or blind geothermal resource. We present a testable, integrated volcanological, petrogenetic, tectonic and hydrothermal conceptual model for 57 ka China Hat and cogenetic topaz rhyolite lava domes of the Blackfoot Volcanic Field. This field is well suited for analysis as a blind resource because of its distinctive combination of (1) young bimodal volcanism, petrogenetic evidence of shallow magma storage and evolution, presence of coeval extension, voluminous travertine deposits, and C- and He-isotopic evidence of active magma degassing; (2) a paucity of hot springs or other obvious indicators of a geothermal resource in the immediate vicinity of the lava domes; and (3) proximity to a region of high crustal heat flow, high-T geothermal fluids at 2.5-5 km depth and micro-seismicity characterized by its swarming nature. Eruptions of both basalt and rhyolite commonly evolve from minor phreatomagmatic to effusive. In our model, transport of both magmatic and possible deep crustal aqueous fluids may be controlled by preexisting crustal structures, including west-dipping thrust faults. Geochemical evolution of rhyolite magma is dominated by mid- to upper-crustal fractional crystallization (with pre-eruption storage and phenocryst formation at ~14 km). Approximately 1.2 km3 of topaz rhyolite have been erupted since 1.4 Ma, yielding an average eruption rate of 0.8 km3/m.y. Given reasonable assumptions of magma cumulate formation and eruption rates, and initial and final volatile concentrations, we infer average H2O and CO2 volatile fluxes from the rhyolite source region of ~2MT/year and 340 T/day, respectively. Lithium flux may be comparable to CO2.

Characterization of the rhyolitic rocks from the Lela ore body using neutron activation analysis

International Nuclear Information System (INIS)

Rodriguez, G.C.; Fortes, B.P.; Guevara, S.R.

1998-01-01

Instrumental neutron activation analysis (INAA) is a well-known analytical method for nondestructive, sensitive and accurate determination of elemental composition of geological samples. In the present work twenty-two elements were determined by INAA in nine rhyolitic geological samples from a wolframium ore body Lela, located in the territory of Isla de la Juventud, Cuba. The obtained results are important for the preliminary geochemical evaluation of the studied rocks. (author)

Slope-apron deposition in an ordovician arc-related setting: The Vuelta de Las Tolas Member (Suri Formation), Famatina Basin, northwest Argentina

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Mangano, M.G.; Buatois, L.A.

1997-01-01

The Ordovician Suri Formation is part of the infill of the Famatina Basin of northwest Argentina, which formed in an active setting along the western margin of early Paleozoic Gondwana. The lower part of this formation, the Vuelta de Las Tolas Member, records sedimentation on a slope apron formed in an intra-arc basin situated on a flooded continental arc platform. The coincidence of a thick Arenig-Llanvirn sedimentary succession and volcanic-plutonic arc rocks suggests an extensional or transtensional arc setting, and is consistent with evidence of an extensional regime within the volcanic arc in the northern Puna region. The studied stratigraphic sections consist of volcanic rocks and six sedimentary facies. The facies can be clustered into four facies associations. Association 1, composed of facies A (laminated siltstones and mudstones) and B (massive mudstones and siltstones), is interpreted to have accumulated from silty-muddy high-and low-density turbidity currents and highly fluid, silty debris flows, with subsequent reworking by bottom currents, and to a lesser extent, hemipelagic suspension in an open-slope setting. Facies association 2 is dominated by facies C (current-rippled siltstones) strata. These deposits are interpreted to record overbank sedimentation from fine-grained turbidity currents. Facies E (matrix-supported volcanic breccias) interbedded with andesitic lava units comprises facies association 3. Deposition was contemporaneous with subaqueous volcanic activity, and accumulated from cohesive debris flows in a coarse-grained wedge at the base of slope. Facies association 4 is typified by facies D (vitric fine-grained sandstones and siltstones) and F (channelized and graded volcanic conglomerates and breccias) deposits. These strata commonly display thinning-and fining-upward trends, indicating sedimentation from highly-concentrated volcaniclastic turbidity currents in a channelized system. The general characteristics of these deposits of fresh

Field-trip guide to Columbia River flood basalts, associated rhyolites, and diverse post-plume volcanism in eastern Oregon

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Ferns, Mark L.; Streck, Martin J.; McClaughry, Jason D.

2017-08-09

The Miocene Columbia River Basalt Group (CRBG) is the youngest and best preserved continental flood basalt province on Earth, linked in space and time with a compositionally diverse succession of volcanic rocks that partially record the apparent emergence and passage of the Yellowstone plume head through eastern Oregon during the late Cenozoic. This compositionally diverse suite of volcanic rocks are considered part of the La Grande-Owyhee eruptive axis (LOEA), an approximately 300-kilometer-long (185 mile), north-northwest-trending, middle Miocene to Pliocene volcanic belt located along the eastern margin of the Columbia River flood basalt province. Volcanic rocks erupted from and preserved within the LOEA form an important regional stratigraphic link between the (1) flood basalt-dominated Columbia Plateau on the north, (2) bimodal basalt-rhyolite vent complexes of the Owyhee Plateau on the south, (3) bimodal basalt-rhyolite and time-transgressive rhyolitic volcanic fields of the Snake River Plain-Yellowstone Plateau, and (4) the High Lava Plains of central Oregon.This field-trip guide describes a 4-day geologic excursion that will explore the stratigraphic and geochemical relationships among mafic rocks of the Columbia River Basalt Group and coeval and compositionally diverse volcanic rocks associated with the early “Yellowstone track” and High Lava Plains in eastern Oregon. Beginning in Portland, the Day 1 log traverses the Columbia River gorge eastward to Baker City, focusing on prominent outcrops that reveal a distal succession of laterally extensive, large-volume tholeiitic flood lavas of the Grande Ronde, Wanapum, and Saddle Mountains Basalt formations of the CRBG. These “great flows” are typical of the well-studied flood basalt-dominated Columbia Plateau, where interbedded silicic and calc-alkaline lavas are conspicuously absent. The latter part of Day 1 will highlight exposures of middle to late Miocene silicic ash-flow tuffs, rhyolite domes, and

Brushy Basin drilling project, Cedar Mountain, Emergy County, Utah

International Nuclear Information System (INIS)

Kiloh, K.D.; McNeil, M.; Vizcaino, H.

1980-03-01

A 12-hole drilling program was conducted on the northwestern flank of the San Rafael swell of eastern Utah to obtain subsurface geologic data to evaluate the uranium resource potential of the Brushy Basin Member of the Morrison Formation (Jurassic). In the Cedar Mountain-Castle Valley area, the Brushy Basin Member consists primarily of tuffaceous and carbonaceous mudstones. Known uranium mineralization is thin, spotty, very low grade, and occurs in small lenticular pods. Four of the 12 drill holes penetrated thin intervals of intermediate-grade uranium mineralization in the Brushy Basin. The study confirmed that the unit does not contain significant deposits of intermediate-grade uranium

The Yellowstone ‘hot spot’ track results from migrating Basin Range extension

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Foulger, Gillian R.; Christiansen, Robert L.; Anderson, Don L.; Foulger, Gillian R.; Lustrino, Michele; King, Scott D.

2015-01-01

Whether the volcanism of the Columbia River Plateau, eastern Snake River Plain, and Yellowstone (western U.S.) is related to a mantle plume or to plate tectonic processes is a long-standing controversy. There are many geological mismatches with the basic plume model as well as logical flaws, such as citing data postulated to require a deep-mantle origin in support of an “upper-mantle plume” model. USArray has recently yielded abundant new seismological results, but despite this, seismic analyses have still not resolved the disparity of opinion. This suggests that seismology may be unable to resolve the plume question for Yellowstone, and perhaps elsewhere. USArray data have inspired many new models that relate western U.S. volcanism to shallow mantle convection associated with subduction zone processes. Many of these models assume that the principal requirement for surface volcanism is melt in the mantle and that the lithosphere is essentially passive. In this paper we propose a pure plate model in which melt is commonplace in the mantle, and its inherent buoyancy is not what causes surface eruptions. Instead, it is extension of the lithosphere that permits melt to escape to the surface and eruptions to occur—the mere presence of underlying melt is not a sufficient condition. The time-progressive chain of rhyolitic calderas in the eastern Snake River Plain–Yellowstone zone that has formed since basin-range extension began at ca. 17 Ma results from laterally migrating lithospheric extension and thinning that has permitted basaltic magma to rise from the upper mantle and melt the lower crust. We propose that this migration formed part of the systematic eastward migration of the axis of most intense basin-range extension. The bimodal rhyolite-basalt volcanism followed migration of the locus of most rapid extension, not vice versa. This model does not depend on seismology to test it but instead on surface geological observations.

Evolution of tertiary intermontane fluvial system of Powder River Basin, Wyoming and Montana

International Nuclear Information System (INIS)

Flores, R.M.; Ethridge, F.G.

1985-01-01

Exploration and development of economic coal and uranium deposits of the Tertiary Fort Union and Wasatch Formations provided data related to the evolution of depositional systems in the Powder River Basin. In ascending order, the Paleocene Fort Union Formation consists of the Tullock, Lebo, and Tongue River Members. The overlying Eocene Wasatch Formation consists of the conglomeratic Kingsbury and Moncrief Members and laterally equivalent finer grained deposits. Evolution of fluvial deposition in the basin was determined from sandstone percent maps. A high proportion of sandstones in the Tullock Member and combined Tongue River Member and Wasatch Formation formed in interconnected east-west and north-south belts. The east-west belts represent alluvial fans, as well as braided and meandering tributary streams. The north-south belts reflect meandering and anastomosing trunk streams fed by basin margin tributaries. The sandstones of the Lebo Shale show east-west trends and represent deposits of fluvio-deltaic systems that filled a western, closed-lacustrine basin. The lake in this basin may have formed during localized subsidence along the Buffalo deep fault. These contrasting styles of fluvial deposition were largely controlled by extrabasinal and intrabasinal tectonics associated with Laramide orogeny

Carboniferous geology and uranium potential of the northeast flank of the Parana Basin and southwest flank of the Parnaiba Basin, Brazil

International Nuclear Information System (INIS)

Andrade, S.M. de; Camarco, P.E.N.

1984-01-01

The Carboniferous sequences of the northeast flank of the Parana Basin and those of the southwest flank of the Parnaiba Basin have been the subject of discussion and polemics for quite a long time, especially in terms of their stratigraphic relations and depositional environments. Thus, we reinforce our main objective, which is to furnish data for the definition of the uranium potential in these Carboniferous sediments, by adding recently acquired information that should aid in the clarification of the existing controversies. The Carboniferous along the northeast flank of the Parana Basin is represented by the Aquidauana Formation which has been informally divided into three members: lower, middle and upper members. The middle member, of marine origin, constitutes a prospective target for uranium and phosphate associations, in which sandstones interbedded with shales constitute the host rocks. On the other hand, the Carboniferous of the southwest margin of the Parnaiba Basin, which encompasses the Longa, Poti and Piaui Formations has shown very remote possibilities of uranium occurrences. The regional structural framework, as reflected by the Carboniferous rocks along both basin flanks, is characterized by homoclines cut by gravity faults. The faults along these weakness zones were occasionally intruded by basic rocks of Cretaceous age. Superimposed on the regional structure, open folds appear in the form of anticlines and domes. These folds are discontinuous structures resulting from uplift due to vertical stresses or result from differential subsidence along the limbs of the folds. (Author) [pt

The effect of prior hydrothermal alteration on the melting behaviour during rhyolite formation in Yellowstone, and its importance in the generation of low-δ18O magmas

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Troch, Juliana; Ellis, Ben S.; Harris, Chris; Ulmer, Peter; Bachmann, Olivier

2018-01-01

Constraining the contribution of crustal lithologies to silicic magmas has important implications for understanding the dynamics of these potentially highly explosive systems. Low-δ18O rhyolite lavas erupted after caldera-forming events in Yellowstone have been interpreted as the products of bulk crustal melting of previously deposited and hydrothermally altered rhyolitic material in the down-dropped caldera roof. For lack of compositional data, the "self-cannibalisation bulk melting"-theory relies on the assumption that hydrothermally altered materials are near-cotectic and hydrous (>3 wt% H2O) and will therefore readily melt at temperatures below 850 °C. In this study, we examine the drillcores Y2, Y9 and Y13 from a USGS drilling campaign in Yellowstone in order to characterise the hydrothermally altered material in terms of major and trace elements, oxygen isotopes and water contents. Rhyolite δ18O values can decrease from "normal" (+5.8 to +6.1‰) on the surface to as low as -5‰ at depths of 100-160 m and probably lower as a function of increasing temperature with depth. While material in the drillcores is variably altered and silicified, oxygen isotope exchange in these samples is not accompanied by systematic changes in major and trace element composition and is independent of uptake of water. More than 75% of the drillcore samples have 1100 °C. Therefore, large-scale bulk melting is unrealistic and low-δ18O rhyolite magmas more likely result from assimilation of <30% partially melted altered crust with low δ18O into a normal-δ18O rhyolite magma from the main reservoir. This mechanism is supported by isotopic mass-balance models as well as thermal and volumetric constraints, and may be similarly applicable to other low-δ18O settings worldwide.

Cordierite-bearing strongly peraluminous Cebre Rhyolite from the eastern Sakarya Zone, NE Turkey: Constraints on the Variscan Orogeny

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Dokuz, Abdurrahman; Külekçi, Elif; Aydınçakır, Emre; Kandemir, Raif; Cihat Alçiçek, M.; Pecha, Mark E.; Sünnetçi, Kadir

2017-05-01

The Cebre Rhyolite with an outcropping area up to 12 km2 is one of the rare extrusions in the Variscan basement of the Sakarya Zone. The unit consists of high-K calc alkaline rhyolites (SiO2 = 74-82 wt.%). Abundant phenocrysts of quartz and K-feldspar are accompanied by subordinate cordierite phenocrysts, rare muscovite microphenocrysts and biotite microcrysts set in a fine-grained groundmass. Three types of rock fragments (xenoliths) have been recognized; (i) porphyritic, (ii) equigranular hypabyssal and (iii) hypocrystalline fragments. Zircon U-Pb dating indicates that the Cebre Rhyolite was extruded at 332.8 ± 4.38 Ma, which post-dates the Variscan low temperature metamorphism and pre-dates the emplacement of I-type granitic intrusions (325-303 Ma).The samples are strongly peraluminous with A/CNK values ranging from 1.48 to 2.95 and A/NK from 1.49 to 2.99. They have very high K2O (3.72-7.42 wt.%) and Al2O3 (10.77-14.11 wt.%) contents, but very low CaO (0.02-0.21 wt.%), Na2O (0.05-0.78 wt.%) and MgO (0.3-0.21 wt.%) contents. The samples show geochemical affinity with the upper continental crust, e.g., enrichment of large ion lithophile elements (LILEs; K, Rb, U, Th, Pb), depletion of high field strength elements (HFSEs; Nb, Ta, Ti), Sr, P and Eu, but ԐNd(t) values (- 3.06 to - 8.75) and isotope ratios of Sr(t)(87Sr/86Sr = 0.70499-0.70915) and Pb(t) (206Pb/204Pb = 16.41-17.570, 207Pb/204Pb = 15.54-15.59, 208Pb/204Pb = 36.20-37.22) are similar to those of the lower crust. Geochemical and isotope data indicate that the Cebre Rhyolite was generated by melting of metapelitic rocks with some addition of intermediate metaigneous derived magma. As a geodynamic model, we propose that the Variscan Orogeny in Turkey was occurred by collision of Gondwana with an arc/terrane separated from the southern margin of Laurussia. This collision was followed shortly after by splitting of oceanic lithosphere into two pieces and sinking down into asthenosphere. Rapid upwelling of

The radioisotopically constrained Viséan onset of turbidites in the Moravian-Silesian part of the Rhenohercynian foreland basin (Central European Variscides)

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Jirásek, Jakub; Otava, Jiří; Matýsek, Dalibor; Sivek, Martin; Schmitz, Mark D.

2018-03-01

The Březina Formation represents the initiation of siliciclastic flysch turbidite sedimentation at the eastern margin of Bohemian Massif or within the Rhenohercynian foreland basin. Its deposition started after drowning of the Devonian carbonate platform during Viséan (Mississippian) times, resulting in a significant interval of black siliceous shale and variegated fossiliferous shale deposition in a starved basin. Near the top of the Březina Formation an acidic volcanoclastic layer (tuff) of rhyolitic composition has been dated with high precision U-Pb zircon chemical abrasion isotope dilution method at 337.73 ± 0.16 Ma. This new radiometric age correlates with the previously inferred stratigraphic age of the locality and the current calibration of the Early Carboniferous geologic time scale. Shales of the Březina Formation pass gradually upwards into the siliciclastics of the Rozstání Formation of the Drahany culm facies. Thus our new age offers one of the few available radioisotopic constraints on the time of onset of siliciclastic flysch turbidites in the Rhenohercynian foreland basin of the European Variscides.

The roles of fractional crystallization, magma mixing, crystal mush remobilization and volatile-melt interactions in the genesis of a young basalt-peralkaline rhyolite suite, the greater Olkaria volcanic complex, Kenya Rift valley

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Macdonald, R.; Belkin, H.E.; Fitton, J.G.; Rogers, N.W.; Nejbert, K.; Tindle, A.G.; Marshall, A.S.

2008-01-01

The Greater Olkaria Volcanic Complex is a young (???20 ka) multi-centred lava and dome field dominated by the eruption of peralkaline rhyolites. Basaltic and trachytic magmas have been erupted peripherally to the complex and also form, with mugearites and benmoreites, an extensive suite of magmatic inclusions in the rhyolites. The eruptive rocks commonly represent mixed magmas and the magmatic inclusions are themselves two-, three- or four-component mixes. All rock types may carry xenocrysts of alkali feldspar, and less commonly plagioclase, derived from magma mixing and by remobilization of crystal mushes and/or plutonic rocks. Xenoliths in the range gabbro-syenite are common in the lavas and magmatic inclusions, the more salic varieties sometimes containing silicic glass representing partial melts and ranging in composition from anorthite ?? corundum- to acmite-normative. The peralkaline varieties are broadly similar, in major element terms, to the eruptive peralkaline rhyolites. The basalt-trachyte suite formed by a combination of fractional crystallization, magma mixing and resorption of earlier-formed crystals. Matrix glass in metaluminous trachytes has a peralkaline rhyolitic composition, indicating that the eruptive rhyolites may have formed by fractional crystallization of trachyte. Anomalous trace element enrichments (e.g. ??? 2000 ppm Y in a benmoreite) and negative Ce anomalies may have resulted from various Na- and K-enriched fluids evolving from melts of intermediate composition and either being lost from the system or enriched in other parts of the reservoirs. A small group of nepheline-normative, usually peralkaline, magmatic inclusions was formed by fluid transfer between peralkaline rhyolitic and benmoreitic magmas. The plumbing system of the complex consists of several independent reservoirs and conduits, repeatedly recharged by batches of mafic magma, with ubiquitous magma mixing. ?? The Author 2008. Published by Oxford University Press. All

Magmatic emulsion texture formed by mixing during extrusion, Rauðafell composite complex, Breiðdalur volcano, eastern Iceland

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Charreteur, Gilles; Tegner, Christian

2013-06-01

The Rauðafell composite complex is part of the Neogene Breiðdalur volcano, eastern Iceland and is composed of a composite feeder dyke, a vent structure and a composite flow. The two end-members of the composite complex are rhyolite and basalt, and both are rich in plagioclase macrocrysts: bytownite in basalt and oligoclase in rhyolite. The rhyolite also includes ferroaugite macrocrysts. The mixed rocks are separated in three textural groups related to mixing proportions. When the basaltic end-member is dominant, a hybrid texture with a homogeneous matrix is observed and the only evidence of mixing is the presence of antecrysts of both end-members. When the basaltic end-member represents c. 65 to 30 % of the mixture, we observe emulsion textures composed of finely co-mingled basalt and rhyolite. The difference between these two textural expressions of mixing is due to effects of diffusion. The third texture shows mafic enclaves suspended in a rhyolitic matrix. In these rocks, the proportion of the basaltic end-member is inferior to 30 %, implying that the basalt froze solid in contact with the rhyolite. Zoning of plagioclase shows that the mixing processes are driven initially by highly efficient micro-mingling; the emulsification is possibly a result of compositional gradient stresses (Korteweg stress) between miscible basalt and rhyolite. This is followed by chemical diffusion (hybridisation) and tend to protect antecrysts from reaction with the primitive magmas. When antecrysts originated in the evolved magma, they undergo dissolution due to thermal disequilibrium during mingling and chemical disequilibrium during hybridisation. We argue that such mixing processes are important in producing intermediate rocks in Iceland and elsewhere that shows only the chemical attributes of an origin by mixing. The preservation of emulsion textures is rare and highly dependent on cooling history.

Diagenetic differences of the Zhenzhuchong Member of Ziliujing Formation in the Jiulongshan–Jiange area, Sichuan Basin

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Mingcai Hou

2015-03-01

Full Text Available The rocks of the Zhenzhuchong Member of the Ziliujing Formation, Jiulongshan–Jiange area in the Sichuan Basin, were analyzed by petrography, XRD, and SEM techniques to investigate their diagenetic history and properties, such as authigenic mineral types, evolution of mixed-layer illite–smectite minerals, the clay assembly, and the fraction of mixed-layer clay minerals. The results revealed that the Zhenzhuchong Member has experienced several important episodes of diagenetic alteration since the deposition, including compaction (pressure-solution, cementation, metasomatism, dissolution, fracturing, and infilling of caves and cracks. It was also observed that diagenetic properties of the Jiulongshan area were significantly different from those of the Jiange area. The rock samples from the Jiulongshan area were characterized by the composition of siliceous and calcareous cements, varying amounts of detrital grains, clay matrix and kaolinite replaced by calcites, a certain amount of rarely dissolved early-stage kaolinite, dickite, and infillings by late-stage calcite. On the other hand, for the rock samples from the Jiange area, the dissolution is a common phenomenon with features of abundant aluminosilicates-dissolution pores or components, but the replacement phenomenon has rarely been seen. These rock samples were characterized by the presence of clay mineral cements, quartz, and dolomite infillings. It indicated that there was a great difference of diagenesis between the two areas in the types, phase, and temperature of diagenetic fluids. Revealing the difference would provide theoretical and practical implications for the exploration of high quality oil and gas reservoirs.

Evidence for a welded tuff in the Rhyolite of Calico Hills

International Nuclear Information System (INIS)

Dickerson, R.P.; Hunter, W.C.

1994-01-01

A welded pyroclastic deposit has been identified in the Rhyolite of Calico Hills near Yucca Mountain, Nevada, where only lava flows and nonwelded pyroclastic deposits were previously described. Field data from Fortymile Wash show that nonwelded, bedded tuff grades upward into partially welded massive ruff, and thence into densely welded vitrophyre. Petrographic data show a progressive decrease in inter- and intragranular porosity and amount of vapor-phase minerals, with increasing welding. Pumice fragments are first deformed, then develop diffuse boundaries which become increasingly obscure with progressive welding. The most densely welded rock is a perlitic vitrophyre. The origin of this welded tuff is not clear, as it could represent an ignimbrite or a tuff fused beneath a thick lava flow

Characterization of the rhyolites from the ore body Lela using neutron activation analysis

International Nuclear Information System (INIS)

Capote Rodriguez, G.; Pena Fortes, B.

1996-01-01

Is the present work 22 elements were determined in nine rhyolitic geological samples from a wolframium ore body Lela located in the territory of La Isla de la Juventud. The results obtained are of great importance for the evaluation of the potentiality of the mentioned rocks as a source of uranium mineralization. The neutron activation analysis is an important analytical method used for a multi-elementary determination in geological samples, because its non-destructive character and high accuracy and precision. The irradiation of the samples was developed in the research reactor RA-6 of the Atomic Center of Bariloche, Argentina

Early Cretaceous MORB-type basalt and A-type rhyolite in northern Tibet: Evidence for ridge subduction in the Bangong-Nujiang Tethyan Ocean

Science.gov (United States)

Fan, Jian-Jun; Li, Cai; Sun, Zhen-Ming; Xu, Wei; Wang, Ming; Xie, Chao-Ming

2018-04-01

New zircon U-Pb ages, major- and trace-element data, and Hf isotopic compositions are presented for bimodal volcanic rocks of the Zhaga Formation (ZF) in the western-middle segment of the Bangong-Nujiang suture zone (BNSZ), northern Tibet. The genesis of these rocks is described, and implications for late-stage evolution of the Bangong-Nujiang Tethyan Ocean (BNTO) are considered. Detailed studies show that the ZF bimodal rocks, which occur as layers within a typical bathyal to abyssal flysch deposit, comprise MORB-type basalt that formed at a mid-ocean ridge, and low-K calc-alkaline A-type rhyolite derived from juvenile crust. The combination of MORB-type basalt, calc-alkaline A-type rhyolite, and bathyal to abyssal flysch deposits in the ZF leads us to propose that they formed as a result of ridge subduction. The A-type ZF rhyolites yield LA-ICP-MS zircon U-Pb ages of 118-112 Ma, indicating formation during the Early Cretaceous. Data from the present study, combined with regional geological data, indicate that the BNTO underwent conversion from ocean opening to ocean closure during the Late Jurassic-Early Cretaceous. The eastern segment of the BNTO closed during this period, while the western and western-middle segments were still at least partially open and active during the Early Cretaceous, accompanied by ridge subduction within the Bangong-Nujiang Tethyan Ocean.

Modelling the petroleum generation and migration of the third member of the Shahejie Formation (Es3) in the Banqiao Depression of Bohai Bay Basin, Eastern China

Science.gov (United States)

Guo, Xiaowen; He, Sheng; Liu, Keyu; Shi, Zhongsheng; Bachir, Sani

2011-01-01

The mudstones in the third member of the Shahejie Formation (Es3) are the primary source rocks in the Banqiao Depression of Bohai Bay Basin. They are rich in organic matter with Total Organic Carbon (TOC) content up to 3.5%. The sandstones in the Es3 member are the deepest proven hydrocarbon reservoir rocks with measured porosity and permeability values ranging from 3.6% to 32.4% and from 0.01 md to 3283.7 md, respectively. One, two and three-dimensional basin modelling studies were performed to analyse the petroleum generation and migration history of the Es3 member in the Banqiao Depression based on the reconstruction of the burial, thermal and maturity history in order to evaluate the remaining potential of this petroleum province. The modelling results are calibrated with measured vitrinite reflectance ( R o), borehole temperatures and some drilling results of 63 wells in the study area. Calibration of the model with thermal maturity and borehole temperature data indicates that the present-day heat flow in the Banqiao Depression varies from 59.8 mW/m 2 to 61.7 mW/m 2 and the paleo-heat flow increased from 65 Ma to 50.4 Ma, reached a peak heat-flow values of approximately 75 mW/m 2 at 50.4 Ma and then decreased exponentially from 50.4 Ma to present-day. The source rocks of the Es3 member are presently in a stage of oil and condensate generation with maturity from 0.5% to 1.8% R o and had maturity from 0.5% to 1.25% R o at the end of the Dongying Formation (Ed) deposition (26 Ma). Oil generation (0.5% R o) in the Es3 member began from about 37 Ma to 34 Ma and the peak hydrocarbon generation (1.0% R o) occurred approximately from 30 Ma to 15 Ma. The modelled hydrocarbon expulsion evolution suggested that the timing of hydrocarbon expulsion from the Es3 member source rocks began from 31 Ma to 10 Ma with the peak hydrocarbon expulsion shortly after 26 Ma. Secondary petroleum migration pathways in the Es3 member of the Banqiao Depression are modelled based on the

Pre-eruptive conditions of the ~31 ka rhyolitic magma of Tlaloc volcano, Sierra Nevada Volcanic Range, Central Mexico

Science.gov (United States)

Macias, J.; Arce, J.; Rueda, H.; Gardner, J.

2008-12-01

Tlaloc volcano is located at the northern tip of the Sierra Nevada Volcanic Range in Central Mexico. This Pleistocene to Recent volcanic range consists from north to south of Tlaloc-Telapón-Teyotl-Iztaccíhuatl-and- Popocatépetl volcanoes. While andesitic to barely dacitic volcanism dominates the southern part of the range (i.e. Popocatépetl and Iztaccíhuatl); dacitic and rare rhyolithic volcanism (i.e. Telapón, Tlaloc) dominates the northern end. The known locus of rhyolitic magmatism took place at Tlaloc volcano with a Plinian-Subplinian eruption that occurred 31 ka ago. The eruption emplaced the so-called multilayered fallout and pumiceous pyroclastic flows (~2 km3 DRE). The deposit consists of 95% vol. of juvenile particles (pumice + crystals) and minor altered lithics 5% vol. The mineral association of the pumice fragments (74-76 % wt. SiO2) consists of quartz + plagioclase + sanidine + biotite and rare oxides set in a glassy groundmass with voids. Melt inclusions in quartz phenocrysts suggest that prior to the eruption the rhyolitic contain ~7% of H2O and Nevado de Toluca volcano (~6 km) some 50 km to the southwest.

A micromorphological study of pedogenic processes in an evolutionary soil sequence formed in late quaternary rhyolitic tephra deposits, North Island, New Zealand.

NARCIS (Netherlands)

Bakker, L.; Lowe, D.J.; Jongmans, A.G.

1996-01-01

The influence of time as a soil forming factor was studied on an evolutionary sequence of five soils (1850 radiocarbo years BP-ca. 120,000 BP) developed in rhyolitic tephra deposits in New Zealand. New micromorphological observations were combined with existing macromorphological, chemical,

The Tunas Formation (Permian) in the Sierras Australes foldbelt, east central Argentina: evidence for syntectonic sedimentation in a foreland basin

Science.gov (United States)

Lopez-Gamundi, O. R.; Conaghan, P. J.; Rossello, E. A.; Cobbold, P. R.

1995-04-01

The Tunas Formation, extensively exposed in the Sierras Australes foldbelt of eastern central Argentina, completes the sedimentation of the Gondwanan (Late Carboniferous-Permian) sequence, locally known as the Pillahuincó Group. The underlying units of the Group show an integrated depositional history which can be explained in terms of glaciomarine sedimentation (Sauce Grande Formation) and postglacial transgression (Piedra Azul and Bonete Formations). This succession also has a rather uniform quartz-rich, sand-sized composition indicative of a cratonic provenance from the Tandilia Massif to the northeast. Early to Late Permian deformation folded and thrusted the southwestern basin margin (Sierras Australes) and triggered the deposition of a 1,500 m — thick, synorogenic prograding wedge, the Tunas Formation, in the adjacent foreland basin (Sauce Grande or Claromecó Basin). Sandstone detrital modes for the Tunas deposits show moderate to low contents of quartz and abundant lithics, mostly of volcanic and metasedimentary origin. Paleocurrents are consistently from the SW. Tuffs interbedded with sandstones in the upper half of Tunas Formation (Early — early Late? Permian) are interpreted as being derived from volcanic glass-rich tuffs settled in a body of water. Extensive rhyolitic ignimbrites and consanguineous airborne tuffaceous material erupted in the northern Patagonian region during that period. The age constraints and similarities in composition between these volcanics and the tuffaceous horizons present in the Sauce Grande, Parana and Karoo Basins suggest a genetic linkage between these two episodes. The intimate relationship between volcanic activity inboard of the paleo-Pacific margin, deformation in the adjacent orogenic belt and subsidence and sedimentation in the contiguous foreland basin constitutes a common motif in the Sauce Grande and Karoo Basins of southwestern Gondwana.

Diagenetic Iron Cycling in Ancient Alkaline Saline Lacustrine Sedimentary Rocks: A Case Study on the Jurassic Brushy Basin Member of the Morrison Formation, Colorado Plateau, USA

Science.gov (United States)

Potter-McIntyre, S. L.; Chan, M. A.; McPherson, B. J. O. L.

2014-12-01

The upper part of the Brushy Basin Member in the Four Corners region of the U.S. was deposited in an ephemeral alkaline saline lake system with copious input of volcanic ash. The variegated shale formation provides a setting for the study of early diagenetic iron cycling that records the action of alkaline saline fluid chemistries reacting with volcaniclastic sediments in the presence of microbes. A bull's-eye pattern of authigenic minerals with increasing alteration towards the basinal center similar to modern alkaline saline lakes provides evidence for an extreme paleoenvironmental interpretation. The purpose of this research is to document specific factors, such as reactive sediments, microbial influences, and grain size that affect concretion formation and iron cycling in an ancient extreme environment. Three broad diagenetic facies are interpreted by color and associated bioturbation features: red, green and intermediate. Diagenetic facies reflect meter-scale paleotopography: red facies represent shallow water to subaerial, oxidizing conditions; green facies reflect saturated conditions and reducing pore water chemistry shortly after deposition, and intermediate facies represent a combination of the previous two conditions. Evidence of biotic influence is abundant and trace fossils exhibit patterns associated with the diagenetic facies. Red diagenetic facies typically contain burrows and root traces and green diagenetic facies exhibit restricted biotic diversity typically limited to algal molds (vugs). Microbial fossils are well-preserved and are in close proximity to specific iron mineral textures suggesting biotic influence on the crystal morphology. Three categories of concretions are characterized based on mineralogy: carbonate, iron (oxyhydr)oxide and phosphate concretions. Concretion mineralogy and size vary within an outcrop and even within a stratigraphic horizon such that more than one main category is typically present in an outcrop. Variation in

Field-based description of rhyolite lava flows of the Calico Hills Formation, Nevada National Security Site, Nevada

Science.gov (United States)

Sweetkind, Donald S.; Bova, Shiera C.

2015-01-01

Contaminants introduced into the subsurface of Pahute Mesa, Nevada National Security Site, by underground nuclear testing are of concern to the U.S. Department of Energy and regulators responsible for protecting human health and safety. The potential for contaminant movement away from the underground test areas at Pahute Mesa and into the accessible environment is greatest by groundwater transport through fractured volcanic rocks. The 12.9 Ma (mega-annums, million years) Calico Hills Formation, which consists of a mixture of rhyolite lava flows and intercalated nonwelded and bedded tuff and pyroclastic flow deposits, occurs in two areas of the Nevada National Security Site. One area is north of the Rainier Mesa caldera, buried beneath Pahute Mesa, and serves as a heterogeneous volcanic-rock aquifer but is only available to study through drilling and is not described in this report. A second accumulation of the formation is south of the Rainier Mesa caldera and is exposed in outcrop along the western boundary of the Nevada National Security Site at the Calico Hills near Yucca Mountain. These outcrops expose in three dimensions an interlayered sequence of tuff and lava flows similar to those intercepted in the subsurface beneath Pahute Mesa. Field description and geologic mapping of these exposures described lithostratigraphic variations within lava flows and assisted in, or at least corroborated, conceptualization of the rhyolite lava-bearing parts of the formation.

Alteration of rhyolitic (volcanic) glasses in natural Bolivian salt lakes. - Natural analogue for the behavior of radioactive waste glasses in rock salt repositories

International Nuclear Information System (INIS)

Abdelouas, A.

1996-06-01

Alteration experiments with the R7T7 glass in three salt brines, saturated respectively in MgCl 2 , MgCl 2 -CaCl 2 and NaCl, showed that the solubilities of most radionuclides are controlled by the secondary phases. Nd, La, and Pr are trapped in powellite, Ce in cerianite, U in coffinite, and Sr is partially immobilized in barite. There is a good similarity between the secondary phases formed experimentally on volcanic glasses and the R7T7 glass altered in MgCl 2 CaCl 2 -saturated brine (formation of hydrotalcite and chlorite-serpentine at short-term and saponite at long-term). These results support the use of volcanic glasses alteration patterns in Mg-rich solutions (seawater, brines) to understand the long-term behavior of nuclear waste glasses and to evaluate the stability of the secondary phases. The study of the sediments of Uyuni (Bolivia) showed that the corrosion rate of the rhyolitic glass in brines at 10 C is 12 to 30 time lower than those of rhyolitic glasses altered in high dilute conditions. The neoformed phases in the sediments are: Smectite, alunite, pyrite, barite, celestite and cerianite. The low alteration rate of rhyolitic glasses in brines and the formation of secondary phases such as smectite, barite and cerianite (also formed during the experimental alteration of the R7T7 glass), permit us to expect the low alteration of nuclear waste glasses at long-term in brines and the trapping of certain radionuclides in secondary phases. (orig.) [de

Post-middle Miocene Tuffs of Bodie Hills and Mono Basin, California: Paleomagnetic Reference Directions and Vertical Axis Rotation

Science.gov (United States)

Lindeman, J. R.; Pluhar, C. J.; Farner, M. J.

2013-12-01

The relative motions of the Pacific and North American plates about the Sierra Nevada-North American Euler pole is accommodated by dextral slip along the San Andreas Fault System (~75%) and the Walker Lane-Eastern California Shear Zone system of faults, east of the Sierra Nevada microplate (~25%). The Bodie Hills and Mono Basin regions lie within the Walker Lane and partially accommodate deformation by vertical axis rotation of up to 60o rotation since ~9.4 Ma. This region experienced recurrent eruptive events from mid to late Miocene, including John et al.'s (2012) ~12.05 Ma Tuff of Jack Springs (TJS) and Gilbert's (1968) 11.1 - 11.9 Ma 'latite ignimbrite' east of Mono Lake. Both tuffs can be identified by phenocrysts of sanidine and biotite in hand specimens, with TJS composed of a light-grey matrix and the latite ignimbrite composed of a grey-black matrix. Our paleomagnetic results show these units to both be normal polarity, with the latite ignimbrite exhibiting a shallow inclination. TJS's normal polarity is consistent with emplacement during subchron C5 An. 1n (12.014 - 12.116 Ma). The X-ray fluorescence analyses of fiamme from TJS in Bodie Hills and the latite ignimbrite located east of Mono Lake reveal them both to be rhyolites with the latite ignimbrite sharing elevated K composition seen in the slightly younger Stanislaus Group (9.0 - 10.2 Ma). We establish a paleomagnetic reference direction of D = 352.8o I = 42.7o α95 = 7.7o n = 5 sites (42 samples) for TJS in the Bodie Hills in a region hypothesized by Carlson (2012) to have experienced low rotation. Our reference for Gilbert's latite ignimbrite (at Cowtrack Mountain) is D = 352.9o I = 32.1o α95 = 4.7o. This reference locality is found on basement highland likely to have experienced less deformation then the nearby Mono Basin since ignimbrite emplacement. Paleomagnetic results from this latite ignimbrite suggests ~98.2o × 5.5o of clockwise vertical axis rotation of parts of eastern Mono Basin since

Lithium and Beryllium By-product Recovery from the Round Top Mountain, Texas, Peraluminous Rhyolite Heavy Rare Earth Deposit

Science.gov (United States)

Pingitore, N. E., Jr.; Clague, J. W.; Gorski, D.

2016-12-01

The technology metals Li and Be combine low mass and unique properties. Li batteries are critical in applications at scales from micro-electronics to automotive and grid storage. Low mass Be structural components are essential in aerospace/defense applications and in non-sparking BeCu alloy oilfield tools. Most Li is sourced from desert salarsin the "Lithium Triangle" of Argentina—Bolivia—Chile. In contrast, Materion Corp mines >80% of global Be at Spor Mountain, UT. The massive peraluminous rhyolite heavy rare earth deposit at Round Top Mountain, TX is also enriched in Li, 500 ppm, and Be, 50 ppm. 2016 prices of 7000/tonne Li2CO3 (19% Li) and 1000/kg Be metal suggest favorable economics to extract Li and Be as by-products of HREE mining. Li and some Be are hosted in annite biotite that comprises up to 5% of the rhyolite. Texas Mineral Resources Corp proposes to heap leach crushed rhyolite with dilute H2SO4to release the yttrofluorite-hosted HREEs. At bench scale the annite biotite dissolves, but not quartz and feldspars (>90% of the rock). A series of 40 high-yield laboratory tests at various acid strength, particle size, and exposure time released up to 350 ppm (70%) of the Li and 14 ppm (30%) of the Be. For a 20,000 tonne/day operation, these recoveries correspond to daily production of >3 tonnes Li and 250 kg Be. Higher Li and Be recoveries also increased yields of gangue elements, Fe & Al, into solution. This complicates subsequent separation of Li, Be, and HREEs from the pregnant leach solution. Recovery of target HREEs did not increase beyond 200 ppm Li and 8 ppm Be recovery. Greater Li and Be recoveries increased acid consumption. Thus the "sweet spot" economics for heap leach is likely under conditions of acid strength, grain size, and exposure time that do not maximize by-product Li and Be recoveries. Evolving market prices for the full target element suite and additional costs to recover and purify the Li and Be must also be considered.

Origins and evolution of rhyolitic magmas in the central Snake River Plain: insights from coupled high-precision geochronology, oxygen isotope, and hafnium isotope analyses of zircon

Science.gov (United States)

Colón, Dylan P.; Bindeman, Ilya N.; Wotzlaw, Jörn-Frederik; Christiansen, Eric H.; Stern, Richard A.

2018-02-01

We present new high-precision CA-ID-TIMS and in situ U-Pb ages together with Hf and O isotopic analyses (analyses performed all on the same grains) from four tuffs from the 15-10 Ma Bruneau-Jarbidge center of the Snake River Plain and from three rhyolitic units from the Kimberly borehole in the neighboring 10-6 Ma Twin Falls volcanic center. We find significant intrasample diversity in zircon ages (ranges of up to 3 Myr) and in δ18O (ranges of up to 6‰) and ɛHf (ranges of up to 24 ɛ units) values. Zircon rims are also more homogeneous than the associated cores, and we show that zircon rim growth occurs faster than the resolution of in situ dating techniques. CA-ID-TIMS dating of a subset of zircon grains from the Twin Falls samples reveals complex crystallization histories spanning 104-106 years prior to some eruptions, suggesting that magma genesis was characterized by the cyclic remelting of buried volcanic rocks and intrusions associated with previous magmatic episodes. Age-dependent trends in zircon isotopic compositions show that rhyolite production in the Yellowstone hotspot track is driven by the mixing of mantle-derived melts (normal δ18O and ɛHf) and a combination of Precambrian basement rock (normal δ18O and ɛHf down to - 60) and shallow Mesozoic and Cenozoic age rocks, some of which are hydrothermally altered (to low δ18O values) by earlier stages of Snake River Plain magmatism. These crustal melts hybridize with juvenile basalts and rhyolites to produce the erupted rhyolites. We also observe that the Precambrian basement rock is only an important component in the erupted magmas in the first eruption at each caldera center, suggesting that the accumulation of new intrusions quickly builds an upper crustal intrusive body which is isolated from the Precambrian basement and evolves towards more isotopically juvenile and lower-δ18O compositions over time.

Stratigraphic architecture of a fluvial-lacustrine basin-fill succession at Desolation Canyon, Uinta Basin, Utah: Reference to Walthers’ Law and implications for the petroleum industry

Science.gov (United States)

Ford, Grace L.; David R. Pyles,; Dechesne, Marieke

2016-01-01

A continuous window into the fluvial-lacustrine basin-fill succession of the Uinta Basin is exposed along a 48-mile (77-kilometer) transect up the modern Green River from Three Fords to Sand Wash in Desolation Canyon, Utah. In ascending order the stratigraphic units are: 1) Flagstaff Limestone, 2) lower Wasatch member of the Wasatch Formation, 3) middle Wasatch member of the Wasatch Formation, 4) upper Wasatch member of the Wasatch Formation, 5) Uteland Butte member of the lower Green River Formation, 6) lower Green River Formation, 7) Renegade Tongue of the lower Green River Formation, 8) middle Green River Formation, and 9) the Mahogany oil shale zone marking the boundary between the middle and upper Green River Formations. This article uses regional field mapping, geologic maps, photographs, and descriptions of the stratigraphic unit including: 1) bounding surfaces, 2) key upward stratigraphic characteristics within the unit, and 3) longitudinal changes along the river transect. This information is used to create a north-south cross section through the basin-fill succession and a detailed geologic map of Desolation Canyon. The cross section documents stratigraphic relationships previously unreported and contrasts with earlier interpretations in two ways: 1) abrupt upward shifts in the stratigraphy documented herein, contrast with the gradual interfingering relationships proposed by Ryder et al., (1976) and Fouch et al., (1994), 2) we document fluvial deposits of the lower and middle Wasatch to be distinct and more widespread than previously recognized. In addition, we document that the Uteland Butte member of the lower Green River Formation was deposited in a lacustrine environment in Desolation Canyon.

Permeability of porour rhyolite

Science.gov (United States)

Cashman, K.; Rust, A.; Wright, H.; Roberge, J.

2003-04-01

The development of permeability in bubble-bearing magmas determines the efficiency of volatile escape during their ascent through volcanic conduits, which, in turn, controls their explosive potential. As permeability requires bubble connectivity, relationships between permeability and porosity in silicic magmas must be controlled by the formation, growth, deformation and coalescence of their constituent bubbles. Although permeability data on porous volcanic pyroclasts are limited, the database can be greatly extended by including data for ceramic and metallic foams1. Several studies indicate that a single number does not adequately describe the permeability of a foam because inertial effects, which predominate at high flow rates, cause deviations from Darcy's law. These studies suggest that permeability is best modeled using the Forschheimer equation to determine both the Darcy permeability (k1) and the non-Darcian (k2) permeability. Importantly, at the high porosities of ceramic foams (75-95%), both k1 and k2 are strongly dependent on pore size and geometry, suggesting that measurement of these parameters provides important information on foam structure. We determined both the connected porosity (by He-pycnometry) and the permeability (k1 and k2) of rhyolitic samples having a wide range in porosity (22-85%) and vesicle textures. In general, these data support previous observations of a power law relationship between connected porosity and Darcy permeability2. In detail, variations in k1 increase at higher porosities. Similarly, k2 generally increases in both mean and standard deviation with increasing porosity. Measurements made on three mutually perpendicular cores from individual pumice clasts suggest that some of the variability can be explained by anisotropy in the vesicle structure. By comparison with ceramic foams, we suggest that the remaining variability results from differences either in average vesicle size or, more likely, in the size of apertures

Conduit dynamics in transitional rhyolitic activity recorded by tuffisite vein textures from the 2008-2009 Chaitén eruption

Directory of Open Access Journals (Sweden)

Elodie eSaubin

2016-05-01

Full Text Available The mechanisms of hazardous silicic eruptions are controlled by complex, poorly-understood conduit processes. Observations of recent Chilean rhyolite eruptions have revealed the importance of hybrid activity, involving simultaneous explosive and effusive emissions from a common vent. Such behaviour hinges upon the ability of gas to decouple from magma in the shallow conduit. Tuffisite veins are increasingly suspected to be a key facilitator of outgassing, as they repeatedly provide a transient permeable escape route for volcanic gases. Intersection of foam domains by tuffisite veins appears critical to efficient outgassing. However, knowledge is currently lacking into textural heterogeneities within shallow conduits, their relationship with tuffisite vein propagation, and the implications for fragmentation and degassing processes. Similarly, the magmatic vesiculation response to upper conduit pressure perturbations, such as those related to the slip of dense magma plugs, remains largely undefined. Here we provide a detailed characterization of an exceptionally large tuffisite vein within a rhyolitic obsidian bomb ejected during transitional explosive-effusive activity at Chaitén, Chile in May 2008. Vein textures and chemistry provide a time-integrated record of the invasion of a dense upper conduit plug by deeper fragmented magma. Quantitative textural analysis reveals diverse vesiculation histories of various juvenile clast types.Using vesicle size distributions, bubble number densities, zones of diffusive water depletion, and glass H2O concentrations, we propose a multi-step degassing/fragmentation history, spanning deep degassing to explosive bomb ejection. Rapid decompression events of ~3-4 MPa are associated with fragmentation of foam and dense magma at ~200-350 metres depth in the conduit, permitting vertical gas and pyroclast mobility over hundreds of metres. Permeable pathway occlusion in the dense conduit plug by pyroclast accumulation

The terminal Permian in European Russia: Vyaznikovian Horizon, Nedubrovo Member, and Permian-Triassic boundary

Science.gov (United States)

Lozovsky, V. R.; Balabanov, Yu. P.; Karasev, E. V.; Novikov, I. V.; Ponomarenko, A. G.; Yaroshenko, O. P.

2016-07-01

The comprehensive analysis of the data obtained on terrestrial vertebrata, ostracods, entomologic fauna, megaflora, and microflora in deposits of the Vyaznikovian Horizon and Nedubrovo Member, as well as the paleomagnetic data measured in enclosing rocks, confirms heterogeneity of these deposits. Accordingly, it is necessary to distinguish these two stratons in the terminal Permian of the East European Platform. The combined sequence of Triassic-Permian boundary deposits in the Moscow Syneclise, which is considered to be the most complete sequence in the East European Platform, is as follows (from bottom upward): Vyatkian deposits; Vyaznikovian Horizon, including Sokovka and Zhukovo members; Nedubrovo Member (Upper Permian); Astashikha and Ryabi members of the Vokhmian Horizon (Lower Triassic). None of the sequences of Permian-Triassic boundary deposits known in the area of study characterizes this sequence in full volume. In the north, the Triassic deposits are underlain by the Nedubrovo Member; in the south (the Klyazma River basin), the sections are underlain by the Vyaznikovian Horizon. The Permian-Triassic boundary adopted in the General Stratigraphic Scale of Russia for continental deposits of the East European platform (the lower boundary of the Astashikha Member) is more ancient than the one adopted in the International Stratigraphic Chart. The same geological situation is observed in the German Basin and other localities where Triassic continental deposits are developed. The ways of solving this problem are discussed in this article.

Resedimented Limestones in Middle and Upper Jurassic Succession of the Slovenian Basin

Directory of Open Access Journals (Sweden)

Boštjan Rožič

2006-12-01

Full Text Available The Middle and Upper Jurassic succession of the Slovenian Basin is characterized by pelagic sedimentation of siliceous limestones and radiolarian cherts. In the southern and central part of the basin two packages of resedimented limestones are interbedded within pelagic sediments. The Lower resedimented limestones are lower-middle Bajocian to lower Callovian in age. In the southern part of the basin they form laterally discontinuous sequences composed of limestone breccias, calcarenites and micritic limestone and in the central part of the basin calcarenite intercalations within pelagic beds. They were transported by turbidity currents from highly productive ooidal shoals of the Dinaric Carbonate Platform. The Lower resedimented carbonates correlate with the lower three members of the Travnik Formation in the Bovec Trough and similarly developed but much thicker Vajont Formation in the Belluno Basin. The difference in thickness is interpreted as a consequence of shallow-water and longshore currents on the Dinaric Carbonate Platform that transported platform material towards southwest in the direction of the Belluno Basin. The Upper resedimented limestones are upper Kimmeridgian to lower Tithonian and occur within radiolarian cherts in the upper part of the succession as calcarenite beds that originated by turbidity currents. Onset of resedimentation coincides with the emersion-related demise of barrier reef and following deposition of micritic and rare oolitic limestones on the Dinaric Carbonate Platform. Approximatelly coeval resedimented limestones occur in the fourth member of the Travnik Formation in the Bovec Trough, but are not reported from the Ammonitico Rosso Superiore Formation in the Belluno Basin.

Rhyolitic calderas and centers clustered within the active andesitic belt of Ecuador's Eastern Cordillera

Energy Technology Data Exchange (ETDEWEB)

Mothes, Patricia A; Hall, Minard L [Instituto Geofisico, Escuela Politecnica Nacional, Quito (Ecuador)], E-mail: pmothes@igepn.edu.ec

2008-10-01

In the Ecuadorian volcanic arc a cluster of scattered rhyolitic and dacitic centers within the mainly andesitic Eastern Cordillera includes large caldera structures (Chalupas, Chacana, Cosanga) as well as smaller edifices, built upon the Paleozoic-Mesozoic metamorphic basement. At the Chacana caldera magmatism dates from 2.7 Ma to historic times. These centers erupted enormous ash flows and thick pumice lapilli falls that covered the InterAndean Valley near Quito. The role of the 50-70 km-thick crust with a notable negative gravity anomaly appears to be related to the generation of this highly silicic magmatism occurring along the crest of the Andes in the NVZ.

Geochemical Characterization of Late Pleistocene and Holocene Tephra Layers from the Basin of Mexico, Central Mexico

Science.gov (United States)

Ortega-Guerrero, Beatriz; Newton, Anthony J.

1998-07-01

In order to aid palaeoenvironmental research of Late Pleistocene and Holocene deposits of central Mexico, tephra layers collected from the sediments of the Texcoco and Chalco sub-basins, in the southern part of the Basin of Mexico, are geochemically characterized and used as stratigraphic markers. The tephra layers range in composition from basaltic andesites to rhyolites and are calc-alkaline. The tephras range in age from >34,000 to ca. 2600 14C yr B.P. New names are used informally to designate correlated tephras. The Tlahuac tephra is present in Chalco, at a depth of 18 m; in the southeastern part of Texcoco, at a depth of around 10 m; and at the Tlapacoya archaeological site, where it had been mistakenly described as basaltic. This basalt-andesite tephra is dated to at least 34,000 14C yr B.P. The Tlapacoya 1 tephra is dated to between 15,020 ± 450 and 14,430 ± 190 yr B.P. and is present in all Chalco sections. The Tlapacoya 2 tephra corresponds to the previously described "pomez gruesa con fragmentos de andesita" (ca. 14,400 yr B.P.) and is present in all Chalco and Texcoco sections. The likely source of these three tephras is the volcano Popocatepetl. Tephra II at Chalco dates to 12,520 ± 135 yr B.P. and correlates with the Upper Toluca Pumice from Nevado de Toluca volcano. These represent the first geochemical glass-shard analysis of tephras from the Basin of Mexico, and so further research is necessary before a reliable tephrochronology can be established.

Diagenesis of the Mucuri Member sandstones, lower cretaceous in the Espirito Santo and Mucuri Basins; Diagenese dos arenitos do Membro Mucuri, cretaceo inferior das Bacias do Espirito Santo e de Mucuri

Energy Technology Data Exchange (ETDEWEB)

Silva, Carlos Manuel de Assis; Anjos, Sylvia Maria Couto dos [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas. Dib. de Geologia e Engenharia de Reservatorios

1996-01-01

The diagenetic evolution of the sandy conglomerate sediments belonging to the Mucuri Member was regionally defined in the basins of Espirito Santo and Mucuri from samples collected in 24 wells at depths varying from 500 m to 3,000 m. Nine hundred meters of core samples were described, and 600 thin sections were prepared to be studied at the petrographic microscope and later at the scanning electron microscope (SEM). Samples were also analyze using X-ray diffraction in order to determine the clay minerals content as well as carbon and oxygen isotopic determination of the carbonate cements. The Mucuri Member consists of Alagoas and pre-Alagoas age sediments from alluvial-fluvial-deltaic environments, of arid climate, deposited during the rift phase of the Espirito Santo and Mucuri basins. The Aptian portion (Alagoas age) presents intercalations of typically marine shales. Thus, the Alagoas age sediments present formation water with a distinctive composition from the pre-Alagoas age sediments (continental) responsible for different diagenetic changes in both packages. Moreover, the pre-Alagoas sediments had a burial history characterized by a longer residence time at greater depths than the Alagoas package, and thereby being more susceptible to mesodiagnetic processes. Most reservoirs of the Mucuri Member are of the Alagoas age, and because of better sampling a more detailed description is given. These reservoirs were also deeply affected by eodiagenesis, with particular emphasis in calcite precipitation in zones of sulfate reduction and methagenesis and authigenesis of smectites, which is the main agent responsible for the large amounts of clay minerals present in these reservoirs. several other diagenetic processes were identified in the Mucuri Member being however less efficient in reducing the pore space. The progressive utilization of the clay minerals, the albitization of the feldspar and the precipitation of quartz overgrowth were the mesodiagenetic features

Stratigraphical sequence and geochronology of the volcanic rock series in caifang basin, south jiangxi

International Nuclear Information System (INIS)

Xu Xunsheng; Wu Jianhua

2010-01-01

The late Mesozoic volcanic rocks in Jiangxi constitute two volcanic belts: the northern is Xiajiang-Guangfeng volcanic belt, the volcanic rocks series belong to one volcano cycle and named Wuyi group which is subdivided into three formations (Shuangfengling formation, Ehuling formation and Shixi formation); the southern is Sannan-Xunwu volcanic belt, the volcanic rocks series in Caifang basin which locates on Sannan-Xunwu volcanic belt also belong to only one volcano cycle. It can be subdivided into two lithology and lithofacies units (upper and lower): the lower unit consists of sedimentary rocks and associated with a subordinate amount of volcanic rocks, it belongs to erupt-deposit facies which is the product of early volcanic stage; the upper unit is mostly composed of volcanic rocks, it belongs to erupt facies that is the volcanic eruption product. SHRIMP zircon U-Pb age of rhyolite? which locates at the top of the upper unit is 130.79 ± 0.73) Ma. According to the new International Stratigraphic Chart, the boundary of Jurassic and Cretaceous is (145.4 ± 4.0) Ma, so the age shows that the geologic period of Caifang volcanic rocks series is early Early Cretaceous epoch. On the basis of lithological correlation, lithofacies and stratigraphic horizon analysis, the volcanic rock series in Caifang basin fall under Wuyi group, and the lower unit could be incorporated into Shuangfengling formation, the upper unit could be incorporated into Ehuling formation. The subdivision of sequence and the determination of geochronology of the volcanic rock series in Caifang basin provide some references for the study of the late Mesozoic volcanic rocks series of the Sannan-Xunwu volcanic belt. (authors)

Provenance of the Lower Triassic Bunter Sandstone Formation: implications for distribution and architecture of aeolian vs. fluvial reservoirs in the North German Basin

DEFF Research Database (Denmark)

Olivarius, Mette; Weibel, Rikke; Friis, Henrik

2017-01-01

Zircon U–Pb geochronometry, heavy mineral analyses and conventional seismic reflection data were used to interpret the provenance of the Lower Triassic Bunter Sandstone Formation. The succession was sampled in five Danish wells in the northern part of the North German Basin. The results show...... Shield did not supply much sediment to the basin as opposed to what was previously believed. Sediment from the Variscan belt was transported by wind activity across the North German Basin when it was dried out during deposition of the aeolian part of the Volpriehausen Member (lower Bunter Sandstone......). Fluvial sand was supplied from the Ringkøbing-Fyn High to the basin during precipitation events which occurred most frequently when the Solling Member was deposited (upper Bunter Sandstone). Late Neoproterozoic to Carboniferous zircon ages predominate in the Volpriehausen Member where the dominant age...

Behavior of nuclear waste elements during hydrothermal alteration of glassy rhyolite in an active geothermal system: Yellowstone National Park, Wyoming

International Nuclear Information System (INIS)

Sturchio, N.C.; Seitz, M.G.

1984-01-01

The behavior of a group of nuclear waste elements (U, Th, Sr, Zr, Sb, Cs, Ba, and Sm) during hydrothermal alteration of glassy rhyolite is investigated through detailed geochemical analyses of whole rocks, glass and mineral separates, and thermal waters. Significant mobility of U, Sr, Sb, Cs, and Ba is found, and the role of sorption processes in their observed behavior is identified. Th, Zr, and Sm are relatively immobile, except on a microscopic scale. 9 references, 2 figures, 2 tables

The nature of the Dakota-Morrison boundary, Southeastern San Juan basin

International Nuclear Information System (INIS)

Aubrey, W.M.

1986-01-01

A thin, discontinuous, fluvial locally conglomeratic sandstone at the vase of the Dakota Sandstone in the vicinity of the southeastern San Juan basin, New Mexico has been named the Encinal Canyon Member of the Dakota Sandstone. In the past, the sandstone beds, placed here in the Encinal Canyon, have been included in the Jackpile sandstone, (an economic unit in the Morrison Formation), in the Burro Canyon Formation, or in the Oak Canyon Member of the Dakota Sandstone. Distinction between the Encinal Canyon Member and the Jackpile sandstone, which are separated by an unconformity that probably spans most of the Early Cretaceous, is economically important. The Jackpile is a primary uranium exploration target, whereas the Dakota contains little known uranium. In the past, the sub-Dakota erosional surface in the southeastern San Juan basin generally was thought to be at the base of the marine and paralic Oak Canyon Member of the Dakota Sandstone, which overlies the Encinal Canyon Member. The unconformity is shown here to be at the base of the fluvial rocks of the Encinal Canyon Member. Local relief at the base of the Encinal Canyon indicates that the sub-Dakota erosional surface formed during a time of regional degradation. Easterly flowing streams scoured underlying units and in some places cut completely through the Jackpile sandstone and the Burro Canyon Formation. The Encinal Canyon was deposited in response to the initial transgression of the Dakota sea. As the sea inundated the area, a transgressive erosional surface formed, and the overlying paralic and marine sediments of the Oak Canyon Member were deposited

Sedimentary architecture of a Plio-Pleistocene proto-back-arc basin: Wanganui Basin, New Zealand

Science.gov (United States)

Proust, Jean-Noël; Lamarche, Geoffroy; Nodder, Scott; Kamp, Peter J. J.

2005-11-01

The sedimentary architecture of active margin basins, including back-arc basins, is known only from a few end-members that barely illustrate the natural diversity of such basins. Documenting more of these basins types is the key to refining our understanding of the tectonic evolution of continental margins. This paper documents the sedimentary architecture of an incipient back-arc basin 200 km behind the active Hikurangi subduction margin, North Island, New Zealand. The Wanganui Basin (WB) is a rapidly subsiding, Plio-Pleistocene sedimentary basin located at the southern termination of the extensional back-arc basin of the active Central Volcanic Region (TVZ). The WB is asymmetric with a steep, thrust-faulted, outer (arc-ward) margin and a gentle inner (craton-ward) margin. It contains a 4-km-thick succession of Plio-Pleistocene sediments, mostly lying offshore, composed of shelf platform sediments. It lacks the late molasse-like deposits derived from erosion of a subaerial volcanic arc and basement observed in classical back-arc basins. Detailed seismic stratigraphic interpretations from an extensive offshore seismic reflection data grid show that the sediment fill comprises two basin-scale mega-sequences: (1) a Pliocene (3.8 to 1.35 Ma), sub-parallel, regressive "pre-growth" sequence that overtops the uplifted craton-ward margin above the reverse Taranaki Fault, and (2) a Pleistocene (1.35 Ma to present), divergent, transgressive, "syn-growth" sequence that onlaps: (i) the craton-ward high to the west, and (ii) uplifted basement blocks associated with the high-angle reverse faults of the arc-ward margin to the east. Along strike, the sediments offlap first progressively southward (mega-sequence 1) and then southeastward (mega-sequence 2), with sediment transport funnelled between the craton- and arc-ward highs, towards the Hikurangi Trough through the Cook Strait. The change in offlap direction corresponds to the onset of arc-ward thrust faulting and the rise of

Study of rhyolitic glasses alteration in contact with natural brines (Bolivia). Application to the study of the long-term behaviour of the R7T7 nuclear glass

International Nuclear Information System (INIS)

Abdelouas, A.

1996-01-01

The purpose of this work is to complement an experimental program on the R7T7 nuclear waste glass alteration in brines at 190 deg C in Germany by the analysis of the structure and the chemical composition of the alteration layers, and to study the alteration of rhyolitic glasses in natural brines from Bolivia as analogue for nuclear waste glasses disposed in salt formations. Alteration experiments with the R7T7 and basaltic glasses and obsidian in MgCl 2 -CaCl 2 -saturated brine at 190 deg. C were also conducted in order to study the influence of the glass composition on the nature of the secondary phases. The experiments with the R7T7 glass in three salt brines, saturated respectively in MgCl 2 , MgCl 2 -CaCl 2 and NaCl, showed that the solubilities of most radionuclides are controlled by the secondary phases. Nd, La, and Pr are trapped in powellite, Ce in cerianite, U in coffinite, and Sr is partially immobilized in barite. These phases are stable for more than one year. There is a good similarity between the secondary phases formed experimentally on volcanic glasses and the R7T7 glass altered in MgCl 2 -CaCl 2 -saturated brine. The abundance of Mg in solution permits the formation of similar magnesian clays on the glass samples independently of the nature of the initial glasses. These results support the use of volcanic glasses alteration patterns in Mg-rich solutions to understand the long-term behavior of nuclear waste glasses and to evaluate the stability of the secondary phases. The study of the sediments of Uyuni (Bolivia) showed that the corrosion rate of the rhyolitic glass in brines at 10 deg. C is 12 to 30 time lower than those of rhyolitic glasses altered in high dilute conditions. The low alteration rate of rhyolitic glasses in brines and the formation of secondary phases such as smectite, barite and cerianite (also formed during the experimental alteration of the R7T7 glass), permit us to expect the low alteration of nuclear waste glasses at long

Characteristics of uranium mineralization and depositional system of host sediments, Bayantala basin, Inner Mongolia autonomous region

International Nuclear Information System (INIS)

Zhu Minqiang; Wu Rengui; Yu Dagan; Chen Anping; Shen Kefeng

2003-01-01

Based upon the research of basin fills at the Bayantala basin, the genetic facies of host sediments have been ascertained and the target beds and their range are delineated. The sand bodies of the Upper Member of Tengge'er Formation deposited in fan delta front is favorable to the formation of uranium mineralization of phreatic-interlayer oxidation. The Saihantala Fm deposited in fluvial system can be divided into Lower Member and Upper Member based on depositional microfacies and paleoclimate. The Lower Member of braided system is the most important target bed enriched in organic matter where basal-channel-type uranium mineralization occurs. Features of alteration and mineralization suggest that the early-stage and the late-stage uranium mineralization are related to phreatic oxidation and interlayer oxidation (roll-type) respectively. Meanwhile, the secondary reduction has superimposed over the earlier mineralization in the area caused by hydrocarbons raising along faults

Comparison of nuclear plant emergency plans of PBNCC members

International Nuclear Information System (INIS)

Kato, W.Y.; Hopwood, J.M.

1987-01-01

The Nuclear Safety Working Group (NSWG) of the Pacific Basin Nuclear Cooperation Committee initiated cooperation among Pacific Basin areas based primarily around emergency planning. The NSWG conducted a review of the emergency response plans of members. This paper briefly reviews and makes a comparison of the emergency response plans, with particular attention on the response organization, the planning zone, and the protective action guidelines for emergencies. Although all areas have adopted the same basic elements of emergency planning and are similar, there are also variances due to different governmental structures, population densities, and available resources. It is found that the most significant difference is in the size of the emergency planning zone. The paper concludes with a discussion on possible future cooperative activities of the working group. (author)

Sedimentology and chemostratigraphy of a Valanginian carbonate succession from the Baja Guajira Basin, northern Colombia

Directory of Open Access Journals (Sweden)

Juan Carlos Silva-Tamayo

Full Text Available ABSTRACT: The Kesima Member of the Palanz Formation constitutes the first record of Cretaceous marine sedimentation along the Baja Guajira Basin, northern Colombia. Sedimentologic and petrographic analyses suggest a deposition along a coral reef dominated rimmed carbonate platform. 87Sr/86Sr values between 0.707350 and 0.707400 suggest a Valanginian (136 - 132 Ma depositional age for the Kesima Member. A positive anomaly on the δ13C values of ~2.2‰ suggests that this rimmed carbonate platform registered the Valanginian Weissert oceanic anoxic event. Although the Weissert oceanic anoxic event resulted on a major drowning of the Circum Tethyan carbonate platforms, it seems to have not affected those from the Circum Caribbean, where several shallow marine carbonate platform successions crop out. The Kesima Member displays a change from an organically produced carbonate factory into an inorganically produced, ooids dominated, carbonate factory during the peak of the Weissert event δ13C anomaly. This change in the carbonate factory, which may represent a major perturbation of the marine carbonate budget along tropical settings during the Weissert event, coincides with a major decrease in global sea level. Finally, the age of the Kesima Member is considerably older than that of other Cretaceous carbonate successions cropping out in other northern South America sedimentary basins (i.e. Perija-Merida, Cesar-Rancheria. Differences in the timing of the Cretaceous marine incursion along northern South America, together with the differences in the Triassic-Jurassic stratigraphy of several sedimentary basins in northern South America, suggest that the Baja Guajira and Maracaibo basins remained as an isolated tectonic block separated from northern South America after the breakup of Pangea.

Reaction of Rhyolitic Magma to its Interception by the IDDP-1 Well, Krafla, 2009

Science.gov (United States)

Saubin, É.; Kennedy, B.; Tuffen, H.; Villeneuve, M.; Watson, T.; Nichols, A. R.; Schipper, I.; Cole, J. W.; Mortensen, A. K.; Zierenberg, R. A.

2017-12-01

The unexpected encounter of rhyolitic magma during IDDP-1 geothermal borehole drilling at Krafla, Iceland in 2009, temporarily created the world's hottest geothermal well. This allowed new questions to be addressed. i) How does magma react to drilling? ii) Are the margins of a magma chamber suitable for long-term extraction of supercritical fluids? To investigate these questions, we aim to reconstruct the degassing and deformation behaviour of the enigmatic magma by looking for correlations between textures in rhyolitic material retrieved from the borehole and the recorded drilling data. During drilling, difficulties were encountered in two zones, at 2070 m and below 2093 m depth. Drilling parameters are consistent with the drill bit encountering a high permeability zone and the contact zone of a magma chamber, respectively. Magma was intercepted three times between 2101-2104.4 m depth, which culminated in an increase in standpipe pressure followed by a decrease in weight on bit interpreted as representing the ascent of magma within the borehole. Circulation returned one hour after the last interception, carrying cuttings of glassy particles, felsite with granophyre and contaminant clasts from drilling, which were sampled as a time-series for the following 9 hours. The nature of glassy particles in this time-series varied through time, with a decrease in the proportion of vesicular clasts and a commensurate increase in dense glassy clasts, transitioning from initially colourless to brown glass. Componentry data show a sporadic decrease in felsite (from 34 wt. %), an increase in glassy particles during the first two hours (from 63 wt. % to 94 wt. %) and an increase in contaminant clasts towards the end of the cutting retrieval period. These temporal variations are probably related to the magma body architecture and interactions with the borehole. Transition from vesicular to dense clasts suggests a change in the degassing process that could be related to an early

Late Palaeozoic calcareous algae in the Pisuerga basin (N-Palencia, Spain)

NARCIS (Netherlands)

Rácz, L.

1965-01-01

The calcareous algae were important rock-builders in the deposition of the many limestone members of the Pisuerga Basin. Systematic descriptions are given of 12 species. The following species are new: Clavaporella reinae, Clavaphysoporella endoi, Epimastopora camasobresensis, Psuedoepimastopora?

The Chacana caldera complex in Ecuador

Energy Technology Data Exchange (ETDEWEB)

Hall, Minard L; Mothes, Patricia A [Instituto Geofisico, Escuela Politecnica Nacional, Quito (Ecuador)], E-mail: volcan_pete@yahoo.com

2008-10-01

The Chacana caldera, located immediately east of Quito, capital of Ecuador, forms the most-northern edifice of Ecuadoros rhyolite province. It is a 50X30 km Pleistocene structure that has remained active into historic times. Vitrophyres, welded tuffs, and ignimbrites of rhyolitic and dacitic composition constitute the outer flanks, meantime syngenetic breccias and tuffs, capped later by extensive dacite lava flows and basin sediments, filled the calderaos depression. A notable resurgence occurred that lifted quiet-water sediments to over 4000 m in elevation. The area has numerous hot springs, and little seismic activity.

The Chacana caldera complex in Ecuador

International Nuclear Information System (INIS)

Hall, Minard L; Mothes, Patricia A

2008-01-01

The Chacana caldera, located immediately east of Quito, capital of Ecuador, forms the most-northern edifice of Ecuadoros rhyolite province. It is a 50X30 km Pleistocene structure that has remained active into historic times. Vitrophyres, welded tuffs, and ignimbrites of rhyolitic and dacitic composition constitute the outer flanks, meantime syngenetic breccias and tuffs, capped later by extensive dacite lava flows and basin sediments, filled the calderaos depression. A notable resurgence occurred that lifted quiet-water sediments to over 4000 m in elevation. The area has numerous hot springs, and little seismic activity.

Development of large-volume rhyolitic ignibrites (LRI'S): The Chalupas Caldera, an example from Ecuador

International Nuclear Information System (INIS)

Hammersley, L.; DePaolo, D.J; Beate, B

2001-01-01

The mechanisms responsible for the generation of large volumes of silicic magma and the eruption of large-volume rhyolitic ignimbrites (LRI's) remain poorly understood. Of particular interest are the relative roles of crustal assimilation, fractional crystallization and magma supply and the processes by which large volumes of magma accumulate in crustal chambers rather than erupt in smaller batches. Isotope geochemistry, combined with study of major and trace element variations of lavas, can be used to infer the relative contribution of crustal material and continued magmatic supply. Timescales for the accumulation of magma can be estimated using detailed geochronology. Magma supply rates can be estimated from eruption rates of nearby volcanoes. In this study we investigate the evolution of the Chalupas LRI, a caldera system in the Ecuadorian Andes where LRI's are rare in comparison to the Southern Volcanic Zone (SVZ) of South America (au)

2D seismic interpretation and characterization of the Hauterivian-Early Barremian source rock in Al Baraka oil field, Komombo Basin, Upper Egypt

Science.gov (United States)

Ali, Moamen; Darwish, M.; Essa, Mahmoud A.; Abdelhady, A.

2018-03-01

Komombo Basin is located in Upper Egypt about 570 km southeast of Cairo; it is an asymmetrical half graben and the first oil producing basin in Upper Egypt. The Six Hills Formation is of Early Cretaceous age and subdivided into seven members from base to top (A-G); meanwhile the B member is of Hauterivian-Early Barremian and it is the only source rock of Komombo Basin. Therefore, a detailed study of the SR should be carried out, which includes the determination of the main structural elements, thickness, facies distribution and characterization of the B member SR which has not been conducted previously in the study area. Twenty 2D seismic lines were interpreted with three vertical seismic profiles (VSP) to construct the depth structure-tectonic map on the top of the B member and to highlight the major structural elements. The interpretation of depth structure contour map shows two main fault trends directed towards the NW-SE and NE to ENE directions. The NW-SE trend is the dominant one, creating a major half-graben system. Also the depth values range from -8400 ft at the depocenter in the eastern part to -4800 ft at the shoulder of the basin in the northwestern part of the study area. Meanwhile the Isopach contour map of the B member shows a variable thickness ranging between 300 ft to 750 ft. The facies model shows that the B member SR is composed mainly of shale with some sandstone streaks. The B member rock samples were collected from Al Baraka-1 and Al Baraka SE-1 in the eastern part of Komombo Basin. The results indicate that the organic matter content (TOC) has mainly good to very good (1-3.36 wt %), The B member samples have HI values in the range 157-365 (mg HC/g TOC) and dominated by Type II/III kerogen, and is thus considered to be oil-gas prone based on Rock-Eval pyrolysis, Tmax values between 442° and 456° C therefore interpreted to be mature for hydrocarbon generation. Based on the measured vitrinite equivalent reflectance values, the B member SR

Organizational aspects of the Warrior Basin Environmental Cooperative

International Nuclear Information System (INIS)

Lasseter, E.L. Jr.

1993-01-01

Beginning in 1987, the coalbed methane industry in the Black Warrior Coal Basin of Alabama was on the verge of a boom. The industry soon recognized plans for development might require significant changes in disposal techniques for produced water or a change in the existing system for issuance of NPDES permits for the discharge of produced water. The industry, working closely with the Alabama Department of Environmental Management (ADEM), resolved this problem through with the formation of the Warrior Basin Environmental Cooperative, Inc. (WBEC), a cooperative venture which constructed and now operates a large-scale, integrated water monitoring system providing real-time water quality data to its member organizations. The monitoring system operated by the WBEC covers a 150 mile reach of the Black Warrior River in Alabama affected by coalbed methane discharges. The system provides its eleven members with access to real-time water quality data and monthly summary reports. The system is functionally integrated with the operational requirements of its members and with relevant NPDES permit requirements. September, 1992 marked the second year of full operation of the system. The concept of cooperative use of large-scale, integrated water monitoring systems and the experience gained in the formation of the WBEC and the operation of its system appear to have many potential benefits beyond the scope of its present application

Pre-eruptive conditions of the Hideaway Park topaz rhyolite: Insights into metal source and evolution of magma parental to the Henderson porphyry molybdenum deposit, Colorado

Science.gov (United States)

Mercer, Celestine N.; Hofstra, Albert H.; Todorov, Todor I.; Roberge, Julie; Burgisser, Alain; Adams, David T.; Cosca, Michael A.

2015-01-01

The Hideaway Park tuff is the only preserved extrusive volcanic unit related to the Red Mountain intrusive complex, which produced the world-class Henderson porphyry Mo deposit. Located within the Colorado Mineral Belt, USA, Henderson is the second largest Climax-type Mo deposit in the world, and is therefore an excellent location to investigate magmatic processes leading to Climax-type Mo mineralization. We combine an extensive dataset of major element, volatile, and trace element abundances in quartz-hosted melt inclusions and pumice matrix glass with major element geochemistry from phenocrysts to reconstruct the pre-eruptive conditions and the source and evolution of metals within the magma. Melt inclusions are slightly peraluminous topaz rhyolitic in composition and are volatile-charged (≤6 wt % H2O, ≤600 ppm CO2, ∼0·3–1·0 wt % F, ∼2300–3500 ppm Cl) and metal-rich (∼7–24 ppm Mo, ∼4–14 ppm W, ∼21–52 ppm Pb, ∼28–2700 ppm Zn, shallow ascent and eruption. Filter pressing, crystal settling, magma recharge and mixing of less evolved rhyolite melt, and volatile exsolution were important processes during magma evolution; the low estimated viscosities (∼105–1010 Pa s) of these H2O- and F-rich melts probably enhanced these processes. A noteworthy discrepancy between the metal contents in the pumice matrix glass and in the melt inclusions suggests that after quartz crystallization ceased upon shallow magma ascent and eruption, the Hideaway Park magma exsolved an aqueous fluid into which Mo, Bi, Ag, Zn, Mn, Cs, and Y strongly partitioned. Given that the Henderson deposit contains anomalous abundances of not only Mo, but also W, Pb, Zn, Cu, Bi, Ag, and Mn, we suggest that these metals were sourced from similar fluids exsolved from unerupted portions of the same magmatic system. Trace element ratios imply that Mo was sourced deep, from either the lower crust or metasomatized mantle. The origin of sulfur remains unresolved

Seasonal variability in CDOM absorption and fluorescence properties in the Barataria Basin, Louisiana, USA.

Science.gov (United States)

Singh, Shatrughan; D'Sa, Eurico; Swenson, Erick

2010-01-01

Absorption and fluorescence properties of chromophoric dissolved organic matter (CDOM) along a 124 km transect in the Barataria Basin, a large estuary located in Louisiana, USA, were investigated during high and low flow periods of the Mississippi River in the spring and winter of 2008-2009. Mean CDOM absorption at 355 nm from the marine to the freshwater end member stations ranged from (3.25 +/- 0.56) to (20.76 +/- 2.43) m(-1) for the three month high flow period whereas it varied from (1.48 +/- 1.08) to (25.45 +/- 7.03) m(-1) for the same stations during low flow period. Corresponding salinity values at these stations indicated the influence of river and shelf exchanges in the lower basin and precipitation and runoff in the upper basin. An inverse relationship of CDOM absorbance and fluorescence with salinity observed in the basin could be a useful indicator of salinity. CDOM fluorescence also varied over a large range showing an approximately 8 to 12-fold increase between the marine and freshwater end members for the two flow seasons. Excitation-emission matrix spectral plots indicated the presence of various fluorescence components with highest being the A-peak, lowest the T-peak, and the C and M-peaks showing similar trends along the transect. During low flow season the A/C ratio were well correlated with station locations indicating increased terrestrial influence towards the upper basin. CDOM absorption and fluorescence at 355 nm were highly correlated and independent of CDOM sources suggesting that fluorescence could be used to characterize CDOM in the basin.

Vertical Structural Variation and Their Development of the Sanukayama Rhyolite Lava in Kozushima Island, Japan

Science.gov (United States)

Furukawa, K.; Uno, K.; Kanamaru, T.; Nakai, K.

2017-12-01

We revealed structural development of the Pleistocene Sanukayama rhyolite lava of Kozushima Island, Japan. The good exposure, with about 130 m thick, provides valuable opportunity to understand the vertical structural variation. This exposure corresponds to the upper half of the lava. The paleomagnetic results show that the lava emplaced in subaerial condition at least in the exposed part. The vertical lithofacies are divided into the pumiceous (25-40 m thick), obsidian (40-60 m), spherulitic (30-50 m) layers from top to base. The pumiceous layer is characterized by massive foliated pumice. The foliation dips are gradually changed from gentle (10-30°) in lower part to steep (around 90°) in upper part. This shows the balloon-like morphology. The massive pumiceous layer would be generated from late stage diapiric inflation of the lava (Fink and Manley, 1987). The obsidian layer is composed of massive and welded-brecciated parts. The ductile-deformed light-colored veins, with a few mm thick, are frequently developed. In the microscopic observation, the veins are composed of broken crystals and obsidian clasts indicating fracturing of the lava followed by ductile deformation such as the RFH process (Tuffen et al., 2003). In this layer, extensive vesiculation and microlite development must have been prevented by higher load pressure and faster cooling, respectively. Consequently, they resulted in formation of the obsidian. The spherulitic layer is characterized by development of the ductile-deformed flow banding. The microscopic observation shows that the bands are formed by the spherulite trail. Furthermore, the microlites are aligned within the spherulites. In the heat-retained inner part of the lava, microlites would be developed around the healed fractures. The microlites acted as nucleation site of spherulite. In transition layer between obsidian and spherulitic layers (obsidian layer. This would be caused by high flow-induced shear arising from their rheological

Zeolitization of intracaldera sediments and rhyolitic rocks in the 1.25 Ma lake of Valles caldera, New Mexico, USA

Science.gov (United States)

Chipera, Steve J.; Goff, Fraser; Goff, Cathy J.; Fittipaldo, Melissa

2008-12-01

Quantitative X-ray diffraction analysis of about 80 rhyolite and associated lacustrine rocks has characterized previously unrecognized zeolitic alteration throughout the Valles caldera resurgent dome. The alteration assemblage consists primarily of smectite-clinoptilolite-mordenite-silica, which replaces groundmass and fills voids, especially in the tuffs and lacustrine rocks. Original rock textures are routinely preserved. Mineralization typically extends to depths of only a few tens of meters and resembles shallow "caldera-type zeolitization" as defined by Utada et al. [Utada, M., Shimizu, M., Ito, T., Inoue, A., 1999. Alteration of caldera-forming rocks related to the Sanzugawa volcanotectonic depression, northeast Honshu, Japan — with special reference to "caldera-type zeolitization." Resource Geol. Spec. Issue No. 20, 129-140]. Geology and 40Ar/ 39Ar dates limit the period of extensive zeolite growth to roughly the first 30 kyr after the current caldera formed (ca. 1.25 to 1.22 Ma). Zeolitic alteration was promoted by saturation of shallow rocks with alkaline lake water (a mixture of meteoric waters and degassed hydrothermal fluids) and by high thermal gradients caused by cooling of the underlying magma body and earliest post-caldera rhyolite eruptions. Zeolitic alteration of this type is not found in the later volcanic and lacustrine rocks of the caldera moat (≤ 0.8 Ma) suggesting that later lake waters were cooler and less alkaline. The shallow zeolitic alteration does not have characteristics resembling classic, alkaline lake zeolite deposits (no analcime, erionite, or chabazite) nor does it contain zeolites common in high-temperature hydrothermal systems (laumontite or wairakite). Although aerially extensive, the early zeolitic alteration does not form laterally continuous beds and are consequently, not of economic significance.

Uniform Distribution of Yttrium and Heavy Rare Earth Elements in Round Top Mountain Rhyolite Deposit , Sierra Blanca Texas, USA: Data, Significance, and Origin

Science.gov (United States)

Pingitore, N. E., Jr.; Clague, J. W.; Gorski, D.

2014-12-01

The Round Top Mountain peraluminous rhyolite, exposed at the surface in Sierra Blanca, Hudspeth County, west Texas, USA, is enriched in yttrium and heavy rare earth elements (YHREEs). Other potentially valuable elements in the deposit include Be, Li, U, Th, Sn, F, Nb, and Ta. Texas Rare Earth Resources Corp. proposes to extract the YHREEs from the host mineral variety yttrofluorite by inexpensive heap leaching with dilute sulfuric acid, which also releases some of the Be, Li, U, F, and Th from other soluble minor minerals. Data: Feldspars and quartz comprise 90-95% of the rhyolite, with pheonocrysts of up to 250 microns set in an aphanitic matrix that hosts the typically sub-micron target yttrofluorite. Reverse circulation cuttings from some 100 drill holes, two drill cores, and outcrop and trench observations suggest striking physical homogeneity through this billion-plus ton surface-exposed laccolith, about 1200 feet high and a mile in diameter (375 x 1600 m). Gray to pink, and other minor hues, color variation derives from magnetite—hematite redox reaction. Plots of Y, 13 REEs, U, Th, and Nb analyses from over 1500 samples collected from 64 drill holes (color codes in figure) exhibit remarkably little variation in the concentration of these elements with geographic position or depth within the laccolith. Importance: Uniform mineralization grades help insure against the mining production surprises often associated with vein deposits and heterogeneous open pit deposits. At Round Top, mine feedstock can be relatively constant over the life of the mine (multiple decades), so the mechanical mining process can be optimized early on and not need expensive alterations later. Likewise, the chemical and physical parameters of the heap leach can be perfected. The sensitive and expensive process of extraction of elements and element groups from the pregnant leach solution and purification also can be optimized. Origin: The remarkable homogeneity of the YHREE distribution

CREATING A GEOLOGIC PLAY BOOK FOR TRENTON-BLACK RIVER APPALACHIAN BASIN EXPLORATION

Energy Technology Data Exchange (ETDEWEB)

Douglas G. Patchen; James Drahovzal; Larry Wickstrom; Taury Smith; Chris Laughery; Katharine Lee Avary

2004-04-01

Private- and public-sector stakeholders formed the new ''Trenton-Black River Appalachian Basin Exploration Consortium'' and began a two-year research effort that will lead to a play book for Trenton-Black River exploration throughout the Appalachian basin. The final membership of the Consortium includes 17 gas exploration companies and 6 research team members, including the state geological surveys in Kentucky, Ohio, Pennsylvania and West Virginia, the New York State Museum Institute and West Virginia University. Seven integrated research tasks are being conducted by basin-wide research teams organized from this large pool of experienced professionals. More than 3400 miles of Appalachian basin digital seismic data have been quality checked. In addition, inquiries have been made regarding the availability of additional seismic data from government and industry partners in the consortium. Interpretations of the seismic data have begun. Error checking is being performed by mapping the time to various prominent reflecting horizons, and analyzing for any anomalies. A regional geological velocity model is being created to make time-to-depth conversions. Members of the stratigraphy task team compiled a generalized, basin-wide correlation chart, began the process of scanning geophysical logs and laid out lines for 16 regional cross sections. Two preliminary cross sections were constructed, a database of all available Trenton-Black River cores was created, and a basin-wide map showing these core locations was produced. Two cores were examined, described and photographed in detail, and were correlated to the network of geophysical logs. Members of the petrology team began the process of determining the original distribution of porous and permeable facies within a sequence stratigraphic framework. A detailed sedimentologic and petrographic study of the Union Furnace road cut in central Pennsylvania was completed. This effort will facilitate the calibration

An approach of understanding acid volcanics and tuffaceous volcaniclastics from field studies: A case from Tadpatri Formation, Proterozoic Cuddapah basin, Andhra Pradesh, India

Science.gov (United States)

Goswami, Sukanta; Upadhyay, P. K.; Bhagat, Sangeeta; Zakaulla, Syed; Bhatt, A. K.; Natarajan, V.; Dey, Sukanta

2018-03-01

The lower stratigraphic part of the Cuddapah basin is marked by mafic and felsic volcanism. Tadpatri Formation consists of a greater variety of rock types due to bimodal volcanism in the upper part. Presence of bimodal volcanism is an indication of continental rift setting. Various genetic processes involved in the formation of such volcanic sequence result in original textures which are classified into volcaniclastic and coherent categories. Detailed and systematic field works in Tadpatri-Tonduru transect of SW Cuddapah basin have provided information on the physical processes producing this diversity of rock types. Felsic volcanism is manifested here with features as finger print of past rhyolite-dacite eruptions. Acid volcanics, tuffs and associated shale of Tadpatri Formation are studied and mapped in the field. With supporting subordinate studies on geochemistry, mineralogy and petrogenesis of the volcanics to validate field features accurately, it is understood that volcanism was associated with rifting and shallow marine environmental condition. Four facies (i.e., surge, flow, fall and resedimented volcaniclastic) are demarcated to describe stratigraphic units and volcanic history of the mapped area. The present contribution focuses on the fundamental characterization and categorization of field-based features diagnostic of silica-rich volcanic activities in the Tadpatri Formation.

Geologic appraisal of Paradox basin salt deposits for water emplacement

Science.gov (United States)

Hite, Robert J.; Lohman, Stanley William

1973-01-01

Thick salt deposits of Middle Pennsylvanian age are present in an area of 12,000 square miles in the Paradox basin of southeast Utah and southwest Colorado. The deposits are in the Paradox Member of the Hermosa Formation. The greatest thickness of this evaporite sequence is in a troughlike depression adjacent to the Uncompahgre uplift on the northeast side of the basin.The salt deposits consist of a cyclical sequence of thick halite units separated by thin units of black shale, dolomite, and anhydrite. Many halite units are several hundred feet thick and locally contain economically valuable potash deposits.Over much of the Paradox basin the salt deposits occur at depths of more than 5,000 feet. Only in a series of salt anticlines located along the northeastern side of the basin do the salt deposits rise to relatively shallow depths. The salt anticlines can be divided geographically and structurally into five major systems. Each system consists of a long undulating welt of thickened salt over which younger rocks are arched in anticlinal form. Locally there are areas along the axes of the anticlines where the Paradox Member was never covered by younger sediments. This allowed large-scale migration of Paradox strata toward and up through these holes in the sediment cover forming diapiric anticlines.The central or salt-bearing cores of the anticlines range in thickness from about 2,500 to 14,000 feet. Structure in the central core of the salt anticlines is the result of both regional-compression and flowage of the Paradox Member into the anticlines from adjacent synclines. Structure in the central cores of the salt anticlines ranges from relatively undeformed beds to complexly folded and faulted masses, in which stratigraphic continuity is undemonstrable.The presence of thick cap rock .over many of the salt anticlines is evidence of removal of large volumes of halite by groundwater. Available geologic and hydrologic information suggests that this is a relatively slow

Basin Analysis of the Mississippi Interior Salt Basin and Petroleum System Modeling of the Jurassic Smackover Formation, Eastern Gulf Coastal Plain, Final Report and Topical Reports 5-8 on Smackover Petroleum system and Underdevelopment Reservoirs

Energy Technology Data Exchange (ETDEWEB)

Mancini, Ernest A.; Puckett, T. Markham; Parcell, William C.; Llinas, Juan Carlos; Kopaska-Merkel, David C.; Townsend, Roger N.

2002-03-05

The Smackover Formation, a major hydrocarbon-producing horizon in the Mississippi Interior Salt Basin (MISB), conformably overlies the Norphlet Formation and is conformably overlain by the Buckner Anhydrite Member of the Haynesville Formation. The Norphlet-Smackover contact can be either gradational or abrupt. The thickness and lithofacies distribution of the Smackover Formation were controlled by the configuration of incipient paleotopography. The Smackover Formation has been subdivided into three informal members, referred to as the lower, middle and upper members.

Drowning unconformity of lacustrine rift basins: A case study from the Dongying Sag in Bohai Bay Basin, China

Science.gov (United States)

Chen, R.; Fan, J.

2015-12-01

The concept of drowning unconformity of lacustrine rift basins was proposed in this paper. This paper utilized 3D seismic data, well-log and the principles methods associated with structural geology, sedimentology and geochemistry, to analyze the drowning unconformity and discuss the origins of drowning unconformity in Dongying Sag in Bohai Bay Basin.Researching on it is not only important for a better understanding of tectonic evolution, palaeogeography and sedimentation of hydrocarbon source rocks, but also a vital guiding significance for the exploration of beach-bar sandstone reservoirs and shale oil.1. The concept of drowning unconformity of lacustrine rift basins is defined. With the consequences of rapid tectonic subsidence in basin, the sharp rise of lake-level and the increased rate of accommodation(A) in basin exceeded the rate of sediment supply(S),namely A>>S, the basin suddenly transformed into deep-water settings from shallow-water settings with sudden change of sediment transport and sediment dispersal patterns. 2.The sequence surface between Sha4 and Sha3 Member of Shahejie Formation is the drowning unconformity(43.5Ma). There are the sedimentary association of the reefs in shallow lacustrine, beach-bar sandstones and glutenite fan bodies under the surface. By contrast, there are the sedimentary association of deep-lake oil shales and shales over the surface. The drowning unconformity in Dongying Sag is a tectonic revolution surface which is changed from extensional tectonics to transtensional tectonics and it is also the surface of discontinuity from shallow lacustrine to deep lacustrine. The responses to sudden changes appeared in the parameters of geophysics, geochemistry and paleontology. 3. With the penetration of India into Asia plate in NNE trending,the subduction zones of Pacific Plate retreated. It caused the rapid downwelling of asthenospheric mantle, followed by the extensive drowning unconformity.

Plio-Pleistocene facies environments from the KBS Member, Koobi Fora Formation: implications for climate controls on the development of lake-margin hominin habitats in the northeast Turkana Basin (northwest Kenya).

Science.gov (United States)

Lepre, Christopher J; Quinn, Rhonda L; Joordens, Josephine C A; Swisher, Carl C; Feibel, Craig S

2007-11-01

Climate change is hypothesized as a cause of major events of Plio-Pleistocene East African hominin evolution, but the vertically discontinuous and laterally confined nature of the relevant geological records has led to difficulties with assessing probable links between the two. High-resolution sedimentary sequences from lacustrine settings can provide comprehensive data of environmental changes and detailed correlations with well-established orbital and marine records of climate. Hominin-bearing deposits from Koobi Fora Ridge localities in the northeast Turkana Basin of Kenya are an archive of Plio-Pleistocene lake-margin sedimentation though significant developmental junctures of northern African climates, East African environments, and hominin evolution. This study examines alluvial channel and floodplain, nearshore lacustrine, and offshore lacustrine facies environments for the approximately 136-m-thick KBS Member (Koobi Fora Formation) exposed at the Koobi Fora Ridge. Aspects of the facies environments record information on the changing hydrosedimentary dynamics of the lake margin and give insights into potential climatic controls. Seasonal/yearly climate changes are represented by the varve-like laminations in offshore mudstones and the slickensides, dish-shaped fractures, and other paleosol features overprinted on floodplain strata. Vertical shifts between facies environments, however, are interpreted to indicate lake-level fluctuations deriving from longer-term, dry-wet periods in monsoonal rainfall. Recurrence periods for the inferred lake-level changes range from about 10,000 to 50,000 years, and several are consistent with the average estimated timescales of orbital precession ( approximately 20,000 years) and obliquity ( approximately 40,000 years). KBS Member facies environments from the Koobi Fora Ridge document the development of lake-margin hominin habitats in the northeast Turkana Basin. Environmental changes in these habitats may be a result of

Sedimentology and palaeontology of the Upper Jurassic Puesto Almada Member (Cañadón Asfalto Formation, Fossati sub-basin), Patagonia Argentina: Palaeoenvironmental and climatic significance

Science.gov (United States)

Cabaleri, Nora G.; Benavente, Cecilia A.; Monferran, Mateo D.; Narváez, Paula L.; Volkheimer, Wolfgang; Gallego, Oscar F.; Do Campo, Margarita D.

2013-10-01

Six facies associations are described for the Puesto Almada Member at the Cerro Bandera locality (Fossati sub-basin). They correspond to lacustrine, palustrine, and pedogenic deposits (limestones); and subordinated alluvial fan, fluvial, aeolian, and pyroclastic deposits. The lacustrine-palustrine depositional setting consisted of carbonate alkaline shallow lakes surrounded by flooded areas in a low-lying topography. The facies associations constitute four shallowing upward successions defined by local exposure surfaces: 1) a Lacustrine-Palustrine-pedogenic facies association with a 'conchostracan'-ostracod association; 2) a Palustrine facies association representing a wetland subenvironment, and yielding 'conchostracans', body remains of insects, fish scales, ichnofossils, and palynomorphs (cheirolepidiacean species and ferns growing around water bodies, and other gymnosperms in more elevated areas); 3) an Alluvial fan facies association indicating the source of sediment supply; and 4) a Lacustrine facies association representing a second wetland episode, and yielding 'conchostracans', insect ichnofossils, and a palynoflora mainly consisting of planktonic green algae associated with hygrophile elements. The invertebrate fossil assemblage found contains the first record of fossil insect bodies (Insecta-Hemiptera and Coleoptera) for the Cañadón Asfalto Formation. The succession reflects a mainly climatic control over sedimentation. The sedimentary features of the Puesto Almada Member are in accordance with an arid climatic scenario across the Upper Jurassic, and they reflect a strong seasonality with periods of higher humidity represented by wetlands and lacustrine sediments.

VOLATILECALC: A silicate melt-H2O-CO2 solution model written in Visual Basic for excel

Science.gov (United States)

Newman, S.; Lowenstern, J. B.

2002-01-01

We present solution models for the rhyolite-H2O-CO2 and basalt-H2O-CO2 systems at magmatic temperatures and pressures below ~ 5000 bar. The models are coded as macros written in Visual Basic for Applications, for use within MicrosoftR Excel (Office'98 and 2000). The series of macros, entitled VOLATILECALC, can calculate the following: (1) Saturation pressures for silicate melt of known dissolved H2O and CO2 concentrations and the corresponding equilibrium vapor composition; (2) open- and closed-system degassing paths (melt and vapor composition) for depressurizing rhyolitic and basaltic melts; (3) isobaric solubility curves for rhyolitic and basaltic melts; (4) isoplethic solubility curves (constant vapor composition) for rhyolitic and basaltic melts; (5) polybaric solubility curves for the two end members and (6) end member fugacities of H2O and CO2 vapors at magmatic temperatures. The basalt-H2O-CO2 macros in VOLATILECALC are capable of calculating melt-vapor solubility over a range of silicate-melt compositions by using the relationships provided by Dixon (American Mineralogist 82 (1997) 368). The output agrees well with the published solution models and experimental data for silicate melt-vapor systems for pressures below 5000 bar. ?? 2002 Elsevier Science Ltd. All rights reserved.

A Mesozoic orogenic cycle from post-collision to subduction in the southwestern Korean Peninsula: New structural, geochemical, and chronological evidence

Science.gov (United States)

Park, Seung-Ik; Kwon, Sanghoon; Kim, Sung Won; Hong, Paul S.; Santosh, M.

2018-05-01

The Early to Middle Mesozoic basins, distributed sporadically over the Korean Peninsula, preserve important records of the tectonic history of some of the major orogenic belts in East Asia. Here we present a comprehensive study of the structural, geochemical, geochronological, and paleontological features of a volcano-sedimentary package, belonging to the Oseosan Volcanic Complex of the Early to Middle Mesozoic Chungnam Basin, within the Mesozoic subduction-collision orogen in the southwestern Korean Peninsula. The zircon U-Pb data from rhyolitic volcanic rocks of the complex suggest Early to Middle Jurassic emplacement age of ca. 178-172 Ma, harmonious with plant fossil taxa found from the overlying tuffaceous sedimentary rock. The geochemical data for the rhyolitic volcanic rocks are indicative of volcanic arc setting, implying that the Chungnam Basin has experienced an intra-arc subsidence during the basin-expanding stage by subduction of the Paleo-Pacific (Izanagi) Plate. The Jurassic arc-related Oseosan Volcanic Complex was structurally stacked by the older Late Triassic to Early Jurassic post-collisional basin-fill of the Nampo Group by the Jangsan fault during basin inversion. The Late Jurassic to Early Cretaceous K-feldspar and illite K-Ar ages marked the timing of inversion tectonics, contemporaneous with the magmatic quiescence in the southern Korean Peninsula, likely due to flat-lying or low-angle subduction. The basin evolution history preserved in the Mesozoic Chungnam Basin reflects a Mesozoic orogenic cycle from post-collision to subduction in the southwestern Korean Peninsula. This, in turn, provides a better understanding of the spatial and temporal changes in Mesozoic tectonic environments along the East Asian continental margin.

Journal of Earth System Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

... we propose a three-fold classification comprising Lower Clastic Unit and an Upper Clastic Unit and a Bimodal (basalt–rhyolite) Volcanic Unit separating the two. Tilting due to basin inversion and faulting has been observed; however, the rocks are unmetamorphosed and show undisturbed primary sedimentary features.

The SHRIMP zircon U-Pb dating of felsic volcanic rocks and its geological significance from yutian group in southern jiangxi

International Nuclear Information System (INIS)

Ji Chunyu; Wu Jianhua

2010-01-01

Past researches have showed that the Rb-Sr isochron ages of felsic end member for r hyolite-basalt b imodal volcanic rocks of Yutian Group in the Changpu and Longnan Basin in Southern Jiangxi Province are 175 ∼ 148 Ma, not only does its amplitude change more significantly, but it does not match with the Rb-Sr isochron ages (179 ∼ 173 Ma) of basic end member. As a result, I choose a method of zircon U-Pb dating with a higher accuracy, to obtain the rhyolite in the bottom of bimodal volcanic rocks in the Changpu Basin and the dacite in the top of of bimodal volcanic rocks in the Longnan Basin, whose zircon SHIRMP U-Pb age are respectively (195.2 ± 2.8) Ma and (191 ± 1.7) Ma. What's more, they are both almost the same in the error limit. It shows that the bimodal volcanic rocks in these both two basins are the product of the same session of magma movement. Simultaneously, it explains they form in a flash during the eruption intervals. According to the the newest International Stratigraphic Chart (Gradsrein et al. , 2004), in terms of geological age, the bimodal volcanic rocks in Changpu Basin and Longnan Basin, belonging to the early Early Jurassic. The zircon SHIRMP U-Pb age are distinctly older than the whole-rock Rb-Sr isochron age, it is probably because of the deviation of the dating method for the wholerock Rb-Sr isochron age. The zircon SHIRMP U-Pb age of bimodal volcanic rocks are 191 ∼ 195 Ma in Southern Jiangxi Province, which indicates that there had been an extensional environment. And after the bimodal volcanic activity, The zircon SHIRMP U-Pb age of felsic volcanic rocks are 145 ∼ 130 Ma. Both of the ages shows a as long as 45 Ma quiet period between 190 Ma and 145 Ma. It is unreasonable possible to interpreted by the single pattern of pacific plate subducting to eurasian plate. (authors)

Sedimentology and paleoenvironments of a new fossiliferous late Miocene-Pliocene sedimentary succession in the Rukwa Rift Basin, Tanzania

Science.gov (United States)

Mtelela, Cassy; Roberts, Eric M.; Hilbert-Wolf, Hannah L.; Downie, Robert; Hendrix, Marc S.; O'Connor, Patrick M.; Stevens, Nancy J.

2017-05-01

This paper presents a detailed sedimentologic investigation of a newly identified, fossiliferous Late Neogene sedimentary succession in the Rukwa Rift Basin, southwestern Tanzania. This synrift deposit is a rare and significant new example of a fossiliferous succession of this age in the Western Branch of East Africa Rift System. The unit, informally termed the lower Lake Beds succession, is late Miocene to Pliocene in age based on cross-cutting relationships, preliminary biostratigraphy, and U-Pb geochronology. An angular unconformity separates the lower Lake Beds from underlying Cretaceous and Oligocene strata. Deposition was controlled by rapid generation of accommodation space and increased sediment supply associated with late Cenozoic tectonic reactivation of the Rukwa Rift and synchronous initiation of the Rungwe Volcanic Centre. The lower Lake Beds, which have thus far only been identified in three localities throughout the Rukwa Rift Basin, are characterized by two discrete lithologic members (herein A and B). The lower Member A is a volcanic-rich succession composed mostly of devitrified volcanic tuffs, and volcaniclastic mudstones and sandstones with minor conglomerates. The upper Member B is a siliciclastic-dominated succession of conglomerates, sandstones, mudstones and minor volcanic tuffs. Detailed facies analysis of the lower Lake Beds reveals various distinctive depositional environments that can be grouped into three categories: 1) alluvial fan; 2) fluvial channel; and 3) flood basin environments, characterized by volcanoclastic-filled lakes and ponds, abandoned channel-fills and pedogenically modified floodplains. Member A represents a shallow lacustrine setting filled by tuffaceous sediments, which grade up into a system of alluvial fans and high-energy, proximal gravel-bed braided rivers. An unconformity marks the contact between the two members. Member B shows an upward transition from a high-energy, gravel-bed braided river system to a sandy

SEA of river basin management plans

DEFF Research Database (Denmark)

Larsen, Sanne Vammen; Kørnøv, Lone

2009-01-01

In, 2000 the European Parliament and the European Council passed the Water Framework Directive (WFD) to be implemented in all Member States. The consequence of the directive is that river basin management plans (RBMPs) shall be prepared which are legally subject to a strategic environmental...... assessment (SEA). An important environmental factor for the water sector is climate change, especially the changes it causes to the water environment. However, based on an argument of an inadequate knowledge base regarding climate change impacts, the prospect of Danish authorities including climate change...

Quaternary volcanism in Deception Island (Antarctica): South Shetland Trench subduction-related signature in the Bransfield Basin back arc domain

International Nuclear Information System (INIS)

Gale, C.; Ubide, T.; Lago, M.; Gil-Imaz, A.; Gil-Pena, I.; Galindo-Zaldivar, J.; Rey, J.; Maestro, A.; Lopez-Martinez, J.

2014-01-01

Deception Island shows a volcanism related to the Phoenix Plate subduction and roll-back under South Shetland Block in the present times. The development of the island is related to the evolution and collapse of a volcanic caldera, and this study is focused on the petrology, mineralogy and geochemistry of the post-caldera rocks. We have made a study of the lava flows, dikes and the youngest historic eruption in 1970. These rocks range from dacite to rhyolite and have a microporphyritic texture with olivine and minor clinopyroxene. A pre-caldera basaltic andesite has also been studied. It has a microporphyritic texture with clinopyroxene. The intermediate and acid compositions alternating in the volcanostratigraphic sequence suggest either mafic recharge events or melt extraction from different levels in the deep magmatic system. All the studied compositions share a subduction-related signature similar to other magmatics from the Bransfield Basin. However, compositional differences between pre-caldera and post-caldera rocks indicate a different magma source and depth of crystallisation. According to the geothermobarometric calculations the pre-caldera magmas started to crystallise at deeper levels (13.5-15 km) than the post-caldera magmas (6.2-7.8 km). Specifically, the postcaldera magmas indicate a smaller influence of the subducting slab in the southwestern part of the Bransfield Basin in respect to the available data from other sectors as well as the involvement of crustal contamination in the genesis of the magmas. (Author)

The Ogaden Basin, Ethiopia: an underexplored sedimentary basin

Energy Technology Data Exchange (ETDEWEB)

Teitz, H.H.

1991-01-01

A brief article examines the Ogaden Basin in Ethiopia in terms of basin origin, basin fill and the hydrocarbon exploration history and results. The natural gas find in pre-Jurassic sandstones, which appears to contain substantial reserves, justifies continuing investigations in this largely underexplored basin. (UK).

A Microsoft Excel interface for rhyolite-MELTS: a tool for research and teaching of magma properties and evolution

Science.gov (United States)

Gualda, G. A.; Ghiorso, M. S.

2013-12-01

The thermodynamic modeling software MELTS (and its derivatives) is a powerful and much utilized tool for investigating crystallization and melting in natural magmatic systems. Rhyolite-MELTS (Gualda et al. 2012, J. Petrol. 53:875-890) is a recent recalibration of MELTS aimed at better capturing the evolution of magmas present in the upper crust (up to ~400 MPa pressure). Currently, most users of rhyolite-MELTS rely on a graphical user interface (GUI), which can be run on UNIX/LINUX and Mac OS X computers. While the interface is powerful and flexible, it can be somewhat cumbersome for the novice and the output is in the form of text files that need to be processed offline. This situation is probably the main reason why MELTS - despite great potential - has not been used more frequently for teaching purposes. We are currently developing an alternative GUI for rhyolite-MELTS using web services consumed by a VBA backend in Microsoft Excel©. The goal is to create a much more interactive tool, that is easy to use that can be made available to a widespread audience, and that will be useful for both research and teaching. The interface is contained within a macro-enabled workbook, which includes editable cells where the user can insert the model input information. Interface buttons initiate computations that are executed on a central server at OFM Research in Seattle (WA). Results of simple calculations are shown immediately within the interface itself. For instance, a user can very rapidly determine the temperature at which a magma of a given composition is completely molten (i.e. find the liquidus); or determine which phases are present, in what abundances, their compositions, and their physical properties (e.g. density, viscosity) at any given combination of temperature, pressure and oxygen fugacity. We expect that using the interface in this mode will greatly facilitate building intuition about magmas and their properties. It is also possible to combine a sequence of

How different institutional arrangements promote integrated river basin management

DEFF Research Database (Denmark)

Nielsen, Helle Ørsted; Frederiksen, Pia; Saarikoski, Heli

2013-01-01

Management Planning processes in six countries around the Baltic Sea. We use theories on multi-level governance, regime interplay and institutional effectiveness. We find that, in most cases, central governments have played a dominant role in the formulation of river basin management plans, while local......, member states must therefore address both the roles of different institutional actors and the interplay among institutions. In this paper, we will explore strengths and weaknesses of different institutional arrangements for integrated water management through a comparative analysis of River Basin...... influence has been somewhat limited. The tight procedural deadlines of the di-rective appear to have pushed for more centralisation than originally intended by the countries. But the analysis also shows that interplay mechanisms such as norms, ideas and incentives do promote effective institutional...

New chronological and geochemical constraints on the genesis and geological evolution of Ponza and Palmarola Volcanic Islands (Tyrrhenian Sea, Italy)

Science.gov (United States)

Cadoux, Anita; Pinti, Daniele L.; Aznar, Cyril; Chiesa, Sergio; Gillot, Pierre-Yves

2005-04-01

A new geochronological and geochemical study of the volcanic rocks of the Ponza and Palmarola Islands, Pontine Archipelago, has been carried out. This archipelago is located along the boundary between the Italian continental shelf and the opening Tyrrhenian basin. It is a key area to study volcanism related to the opening of the Tyrrhenian Sea. Ponza is the oldest felsic magmatic manifestation in the central Tyrrhenian area. Previous studies suggested that Ponza volcanic activity began before 5 Ma. Twenty-five new K-Ar ages constrain the volcanic activity (rhyolitic hyaloclastites and dykes) to the last 4.2 Ma, with two episodes of quiescence between 3.7 and 3.2 Ma and between 2.9 and 1.0 Ma. A new volcanic episode dated at 3.2-2.9 Ma has been identified on the central and southern Ponza, with emplacement of pyroclastic units. At 1.0 Ma, a trachytic episode ended the volcanic activity. The near island of Palmarola exhibits rhyolitic hyaloclastites and domes dated between 1.6 and 1.5 Ma, indicating that the island was entirely built during the Early Pleistocene in a short span of time of ca. 120 ka. Although only 6-8 km apart, the two islands display significantly different geochemical signatures. Ponza rhyolites show major and trace element compositions representative of orogenic magmas of subduction/collision zones: high-K calc-alkaline and metaluminous rhyolites (Agpaitic Index [AI] and Alumina Saturation Index [ASI] 3), and Nb-Ta negative anomalies. In Palmarola, the orogenic character is also present, but much less marked than in Ponza: rhyolites have a peralkaline character (AI>1), lower LILE/HFSE (Th/Ta=11-15), low LREE/HFSE ratios (La/Nb=1-2) close to those of anorogenic lavas, and the Nb-Ta negative anomalies are almost absent. Y/Nb ratios indicate different magmatic sources, one similar to island-arc or active continental margin basalts for Ponza rhyolites, and the others probably involving an OIB type component for Palmarola rhyolites and Ponza trachytes

The mineralogy and genesis of uranium in rhyolitic ignimbrites of Precambrian age from Duobblon, Sweden

International Nuclear Information System (INIS)

Smellie, J.A.T.

1982-01-01

The Duobblon rhyolitic ignimbrites, of middle Precambrian age are 60 m thick. They consist of at least three flows with varying degrees of welding and have undergone devitrification, producing lithophysal and spherulitic textures. They are overlain by thick fluviatile red-bed-type conglomerates and sandstones, which in turn are capped by terrestrial acid volcanics. Uranium enrichments of up to 3000 ppm U occur within two or three peneconcordant tabular horizons which are mostly lithophysae-bearing. Fission-track investigations of the ignimbrites and overlying conglomerates and sandstones, which supplement earlier mineralogical studies, show that U occurs as fine pitchblende disseminations; as complex uranotitanates associated with Fe-Ti-Mn oxides; and as coatings associated with matrix sericite. Small amounts of U are present in such primary accessory minerals as sphene, apatite, and zircon. It is suggested that oxidizing U-bearing solutions, generated partly during devitrification of the ignimbrites and partly from the overlying volcano-sedimentary pile, produced the U enrichments with later sulphide deposition, along the more permeable lithophysal horizons in the ignimbrites. (author)

Preliminary report on the geology of the Lakeview uranium area, Lake County, Oregon

International Nuclear Information System (INIS)

Walker, G.W.

1980-01-01

This study was directed partly toward determining uranium resources, but, more specifically toward establishing the geochemical relations of uranium and other metals with rhyolite bodies in the Lakeview uranium area and to compare these bodies with similar rhyolitic bodies outside the area. The ultimate goal of this work was to determine, if possible, the uranium resource potential of these kinds of rocks over an area of several thousand square kilometers and to apply knowledge gained from this resource assessment to similar terranes within the Northern Basin and Range Province. The regional evaluation is still in progress, and its results will be reported at some appropriate time in the future. To these ends a review was made of previous geologic studies of the area and of the uranium deposits themselves, and some regional geologic mapping was done at a scale of 1:24,000. A geologic map was prepared of an area covering about 450 km 2 (approx. 170 mi 2 ), more or less centered on the White King and Lucky Lass mines and on the major cluster of uranium-bearing rhyolites, and some geologic reconnaissance and attendant sampling of rhyolite intrusives and extrusives well outside the Lakeview uranium area were completed. Isotopic dates were obtained on some units and magnetic polarity characteristics were determined on many units in order to more firmly establish age and stratigraphic relations of the diverse volcanic and volcaniclastic units of the region. Major oxide chemistry and selected trace-element chemistry were obtained on those rhyolitic units suitable for analysis in order to establish distribution patterns for uranium, as well as several other metals, in the rhyolitic rocks of the Lakeview uranium area and to make regional correlations with other analyzed rhyolitic rocks

No effect of H2O degassing on the oxidation state of hydrous rhyolite magmas: a comparison of pre- and post-eruptive Fe2+ concentrations in six obsidian samples from the Mexican and Cascade arcs

Science.gov (United States)

Waters, L.; Lange, R. A.

2011-12-01

The extent to which degassing affects the oxidation state of arc magmas is widely debated. Several researchers have examined how degassing of mixed H-C-O-S-Cl fluids may change the Fe3+/FeT ratio of magmas, and it has been proposed that degassing may induce either oxidation or reduction depending on the initial oxidation state. A commonly proposed oxidation reaction is related to H2O degassing: H2O (melt) + 2FeO (melt) = H2 (fluid) + Fe2O3 (melt). Another mechanism by which H2O degassing can affect the iron redox state is if dissolved water affects the activity of ferrous and/or ferric iron in the melt. Although Moore et al. (1995) presented experiments showing no evidence of an affect of dissolved water on the activity of the ferric-ferrous ratio in silicate melts, other experimental results (e.g., Baker and Rutherford, 1996; Gaillard et al., 2001; 2003) indicate that there may be such an effect in rhyolite liquids. It has long been understood that rhyolites, owing to their low total iron concentrations, are more sensitive than other magma types to degassing-induced change in redox state. Therefore, a rigorous test of whether H2O degassing affects the redox state of arc magmas is best evaluated on rhyolites. In this study, a comparison is made between the pre-eruptive (pre-degassing) Fe2+ concentrations in six, phenocryst-poor (volatiles, as indicated by the low loss on ignition values (LOI ≤ 0.7 wt%). In order to test how much oxidation of ferrous iron occurred as a consequence of that degassing, we measured the ferrous iron concentration in the bulk samples by titration, using the Wilson (1960) method, which was successfully tested again three USGS and one Canadian Geological Survey standards. Our results indicate no detectable change within analytical error between pre- and post-eruptive FeO concentrations, with an average deviation of 0.09 wt% and a maximum deviation of 0.15 wt%. Our results show that H2O degassing has no effect on the redox state of

Characteristics of interlayer oxidation zone and uranium metallogenetic prospect of Zhiluo formation in Daliuta area, Ordos Basin

International Nuclear Information System (INIS)

Yang Jianxin; Li Xide; Zhang Zhaolin

2006-01-01

Ordos Basin is a large down-warping basin in the northwest of North-China Platform; Daliuta area is located in the northeast of Ordos Basin. In this area, sand bodies of fluvial facies developed well in the submember of the lower member of the target Zhiluo Formation of Middle Jurassic and several sand belt of large scale occurred. Yellow interlayer oxidation zone have been discovered in belt I and belt III by the drilling and it is of a certain scale. Due to the young age of interlayer oxidation and unsatisfied uranium sources, uranium metallogenic prospect of this area need more research and exploration. (authors)

Link between Neogene and modern sedimentary environments in the Zagros foreland basin

Science.gov (United States)

Pirouz, Mortaza; Simpson, Guy; Bahroudi, Abbas

2010-05-01

The Zagros mountain belt, with a length of 1800 km, is located in the south of Iran and was produced by collision between the Arabian plate and the Iran micro plate some time in the early Tertiary. After collision, the Zagros carbonate-dominated sedimentary basin has been replaced by a largely clastic system. The Neogene Zagros foreland basin comprises four main depositional environments which reflect the progressive southward migration of the deformation front with time. The oldest unit - the Gachsaran formation - is clastic in the northern part of the basin, but is dominated by evaporates in southern part, being deposited in a supratidal Sabkha-type environment. Overlying the Gachsaran is the Mishan formation, which is characterized by the Guri limestone member at the base, overlain by marine green marls. The thickness of the Guri member increases dramatically towards the southeast. The next youngest unit is the Aghajari Formation which consists of well sorted lenticular sandstone bodies in a red silty-mudstone. This formation is interpreted as representing the floodplain of dominantly meandering rivers. Finally, the Bakhtiari formation consists of mainly coarse-grained gravel sheets which are interpreted to represent braided river deposits. Each of these Neogene depositional environments has a modern day equivalent. For example, the braided rivers presently active in the Zagros mountains are modern analogues of the Bakhtiari. In the downstream direction, these braided rivers become meandering systems, which are equivalents of the Aghajari. Eventually, the meandering rivers meet the Persian gulf which is the site of the ‘modern day' Mishan shallow marine marls. Finally, the modern carbonate system on the southern margin of Persian Gulf represents the Guri member paleo-environment, behind which Sabkha-type deposits similar to the Gachsaran are presently being deposited. One important implication of this link between the Neogene foreland basin deposits and the

Lithofacies paleogeography and sedimentary model of Sinian Dengying Fm in the Sichuan Basin

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Jingao Zhou

2017-05-01

Full Text Available For predicting the distribution of favorable reservoir facies belts of the super-large ancient Anyue carbonate gas field in the Sichuan Basin, through an analysis of structure and lithofacies paleogeography, the lithofacies paleogeography and sedimentary model of the Sinian Dengying Fm was reconstructed based on the field outcrop, drilling and seismic data. As a result, achievements are made in four aspects. First, the basin and its periphery resided in an extensional tectonic setting in the Sinian. Intense extension led to the formation of the Deyang–Anyue intra-platform rift. The Sichuan Basin was divided into the palaeo-geographic pattern of “two uplifts and four sags”. The “two uplifts” evolved into the platform, and the “four sags” evolved into the slope-basin environment. Second, in the depositional stage of the Deng 2 Member, some favorable reservoir belts developed, such as bioherm-shoal at the continental margin, bioherm-shoal at the rift margin, and bioherm-shoal in the platform. The bioherm-shoal at rift margin developed along both sides of the Deyang–Anyue rift, in a U-shape, with a width of about 5–40 km and a length of about 500 km. It connected with the platform margin belt at the continental margin to the west in the Shifang area, and to the north near Guangyuan area. Third, in the depositional stage of the Deng 4 Member, when the lithofacies paleogeographic features in the Deng 2 Member remained, the platform margin belt at the rift margin evolved into two parts in the east and the west as a result of the continuous southward extensional faulting of the Deyang–Anyue rift until it finally crossed the basin from north to south. The eastern platform margin belt was located in the Guangyuan–Yanting–Anyue–Luzhou area, showing NS distribution with a length of about 450 km and a width of about 4–50 km. The western platform margin belt mainly developed in the Dujiangyan�

On Dams in the Amazon Basin, Teleconnected Impacts, and Neighbors Unaware of the Damage to their Natural Resources and Assets.

Science.gov (United States)

Latrubesse, E. M.; Park, E.

2017-12-01

In a recent study, Latrubesse et al., (2017) demonstrated that the accumulated negative environmental effects of more than one hundred existing dams and at least 288 proposed dams, if constructed, will trigger massive hydrophysical and biotic disturbances that will affect the Amazon basin's floodplains, estuary and sediment plume. The authors introduced a Dam Environmental Vulnerability Index (DEVI) to quantify the current and potential impacts of dams in the basin. The current and potential vulnerabilities of different regions of the Amazon basin was assessed, and the results highlighted the need for a more efficient and integrative legal framework involving all nine countries of the basin in an anticipatory assessment to minimize the negative socio-environmental and biotic impacts of hydropower developments. Here we present expanded information on the potential impacts of dams in the lower Amazon and the northeast Atlantic coast of South America, and revisit our proposed integrative strategies for basin management which are based on the adaptation and functionality of the institutional and legal framework already existing in the Amazon countries. Participative strategies involving members from the Amazon Cooperation Treaty Organization (ACTO) countries, and additional members (for example, France), such as the creation of a basin committee -as defined by the Brazilian Law of Waters of Brazil-, and the creation of an Amazon Basin Panel allowing the participation of scientists that could have a policy-relevant role but should be not policy-prescriptive, are also discussed. ReferencesLatrubesse, E., Arima E. Dunne T., Park E., Baker V, Horta F.,Wight, C., Wittmann F., Zuanon, J., Baker P., Ribas C, Norgaard R., Filizola N., Ansar A., Flyvbjerg B., Stevaux, J. 2017. Damming the rivers of the Amazon basin. Nature, 546, 363-369.

Integrated Hydrographical Basin Management. Study Case - Crasna River Basin

Science.gov (United States)

Visescu, Mircea; Beilicci, Erika; Beilicci, Robert

2017-10-01

Hydrographical basins are important from hydrological, economic and ecological points of view. They receive and channel the runoff from rainfall and snowmelt which, when adequate managed, can provide fresh water necessary for water supply, irrigation, food industry, animal husbandry, hydrotechnical arrangements and recreation. Hydrographical basin planning and management follows the efficient use of available water resources in order to satisfy environmental, economic and social necessities and constraints. This can be facilitated by a decision support system that links hydrological, meteorological, engineering, water quality, agriculture, environmental, and other information in an integrated framework. In the last few decades different modelling tools for resolving problems regarding water quantity and quality were developed, respectively water resources management. Watershed models have been developed to the understanding of water cycle and pollution dynamics, and used to evaluate the impacts of hydrotechnical arrangements and land use management options on water quantity, quality, mitigation measures and possible global changes. Models have been used for planning monitoring network and to develop plans for intervention in case of hydrological disasters: floods, flash floods, drought and pollution. MIKE HYDRO Basin is a multi-purpose, map-centric decision support tool for integrated hydrographical basin analysis, planning and management. MIKE HYDRO Basin is designed for analyzing water sharing issues at international, national and local hydrographical basin level. MIKE HYDRO Basin uses a simplified mathematical representation of the hydrographical basin including the configuration of river and reservoir systems, catchment hydrology and existing and potential water user schemes with their various demands including a rigorous irrigation scheme module. This paper analyzes the importance and principles of integrated hydrographical basin management and develop a case

The melt inclusion record from the rhyolitic Kos Plateau Tuff (Aegean Arc)

Science.gov (United States)

Bachmann, Olivier; Wallace, Paul J.; Bourquin, Julie

2010-02-01

The >60 km3 rhyolitic Kos Plateau Tuff provides an exceptional probe into the behavior of volatile components in highly evolved arc magmas: it is crystal-rich (30-40 vol% crystals), was rapidly quenched by the explosive eruptive process, and contains abundant homogeneous melt inclusions in large quartz crystals. Several methods for measuring major, trace and volatile element concentrations (SIMS, FTIR, Raman spectroscopy, electron microprobe, LA-ICPMS) were applied to these melt inclusions. We found a ~2 wt% range of H2O contents (4.5-6.5 wt% H2O, measured independently by SIMS, FTIR, and Raman spectroscopy) and relatively low CO2 concentrations (15-140 ppm measured by FTIR, with most analyses <100 ppm). No obvious correlations between H2O, CO2, major and trace elements are observed. These observations require a complex, protracted magma evolution in the upper crust that included: (1) vapor-saturated crystallization in a chamber located between 1.5 and 2.5 kb pressure, (2) closed-system degassing (with up to 10 vol% exsolved gas) as melts percolated upwards through a vertically extensive mush zone (2-4 km thick), and (3) periodic gas fluxing from subjacent, more mafic and more CO2-rich magma, which is preserved as andesite bands in pumices. These processes can account for the range of observed H2O and CO2 values and the lack of correlation between volatiles and trace elements in the melt inclusions.

The advance of Kos Plateau Tuff ignimbrite into the marine realm of the Kalymnos Basin, SE Aegean Sea.

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Markakis, Emmanouil; Anastasakis, George

2013-04-01

The 161 ka Kos Plateau Tuff (KPT) eruption is considered to be the largest explosive Quaternary event in the eastern Mediterranean. It produced pumice rafts followed by "non-welded ignimbrites" that are up to 30m thick, especially widespread on Kos island and covering an area of > 80 Km2 that includes mainly islands and present marine regions. Pyroclastic flows travelled from the proposed vent, that lies between and around Yali and Nisyros islands, across present land and sea, the total volume of the tuff has been estimated as at least 100km3. KPT products principally consist of rhyolitic ash and pumice. Post 2010 Athens University oceanographic missions have mapped the seafloor around the volcanic islands of the SE Aegean Sea. Here we present new data on seafloor morphology and Upper Quaternary seafloor stratigraphy of the Kalymnos basin that extends over an area over 70km2 and map the advance and deposition of the KPT that was previously unknown in this region. The Kalymnos basin is roughly triangular in shape and essentially consists of two sedimentation depocenters: a) a roughly elliptical 400 m deep northern segment that is developed sub-parallel to Kalymnos Island and its W-SW shelf; b) a rather physiographically complex western sector developed NE of Astipalea island and reaching depths of over 620m. High resolution sparker profiles from the west Kos-Kalymnos shelf reveal an outstanding seismic stratigraphy of stacked and prograded coastal clinoform packets capped by erosional transgressive surfaces that record Quaternary eustatic lowstands deposits of sea level with clinoforms developing during forced regression and the erosional surfaces during transgression. We show that a massive gravity flow deposit is intercalated with the shelf sediments. Above it low sea level MIS 6 and 2 sedimentary sequences are fully developed and below stage 8-10 sediments are erratically preserved over stages 12 and 16 sediments. This gravity flow deposit swept across the shelf

How does Diversity Matter? The Case of Brazilian River Basin Councils

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Andrew Reid. Bell

2011-03-01

Full Text Available Diversity as a concept has often been perceived as a positive system attribute to pursue and protect. However, in some social settings, the way different kinds of diversity shape outcomes can vary significantly. Diversity of ideas and individuals sometimes can lead to disagreement and conflict, which in turn can lead to both positive and negative outcomes. In this study, we examine identity diversity, i.e., age, income, education, worldviews, etc., within the context of Brazilian water governance. We find that within the basins studied in this project, first, the more diversity in organizations and the sectors represented on the council, the more council members participate in council activities, perceive decision making to be democratic, and perceive technical information to facilitate decision making. Second, diversity in what members perceive to be the most pressing problems facing the basin and also diversity in worldviews often correlate negatively with some measures of participation and the perceived importance of technical knowledge. Third, diversity in the level of experience with water issues negatively correlates with some measures of participation and perceived democratic decision making. Fourth, diversity in the perception of the most important problem facing the basin leads to poorer outcomes in the council. Our work provides an argument for supporting broad sectoral representation of interests within deliberative decision making bodies; however, it also illustrates that it is critical for these bodies to explore ways to resolve basic disagreements about the most important problems that need to be addressed and where their collective efforts should be focused.

Cambrian–early Ordovician volcanism across the South Armorican and Occitan domains of the Variscan Belt in France: Continental break-up and rifting of the northern Gondwana margin

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André Pouclet

2017-01-01

Full Text Available The Cambrian–lower Ordovician volcanic units of the South Armorican and Occitan domains are analysed in a tectonostratigraphic survey of the French Variscan Belt. The South Armorican lavas consist of continental tholeiites in middle Cambrian–Furongian sequences related to continental break-up. A significant volcanic activity occurred in the Tremadocian, dominated by crustal melted rhyolitic lavas and initial rifting tholeiites. The Occitan lavas are distributed into five volcanic phases: (1 basal Cambrian rhyolites, (2 upper lower Cambrian Mg-rich tholeiites close to N-MORBs but crustal contaminated, (3 upper lower–middle Cambrian continental tholeiites, (4 Tremadocian rhyolites, and (5 upper lower Ordovician initial rift tholeiites. A rifting event linked to asthenosphere upwelling took place in the late early Cambrian but did not evolve. It renewed in the Tremadocian with abundant crustal melting due to underplating of mixed asthenospheric and lithospheric magmas. This main tectono-magmatic continental rift is termed the “Tremadocian Tectonic Belt” underlined by a chain of rhyolitic volcanoes from Occitan and South Armorican domains to Central Iberia. It evolved with the setting of syn-rift coarse siliciclastic deposits overlain by post-rift deep water shales in a suite of sedimentary basins that forecasted the South Armorican–Medio-European Ocean as a part of the Palaeotethys Ocean.

Rate of deformation in the Pasco Basin during the Miocene as determined by distribution of Columbia River basalt flows

International Nuclear Information System (INIS)

Reidel, S.P.; Ledgerwood, R.K.; Myers, C.W.; Jones, M.G.; Landon, R.D.

1980-03-01

Detailed mapping of over 8000 square kilometers and logs from 20 core holes were used to determine the distribution and thickness of basalt flows and interbeds in the Pasco Basin. The data indicate the high-MgO Grande Ronde Basalt and Wanapum Basalt thicken from the northeast to the southwest. Deformation began in late Frenchman Springs time in the Saddle Mountains along a northwest-southeast trend and in Roza time along an east-west trend. By late Wanapum time, basalt flows were more restricted on the east side. Saddle Mountains Basalt flows spread out in the basin from narrow channels to the east. The Umatilla Member entered from the southeast and is confined to the south-central basin, while the Wilbur Creek, Asotin, Esquatzel, Pomona, and Elephant Mountain Members entered from the east and northeast. The distribution of these members is controlled by flow volume, boundaries of other flows, and developing ridges. The Wilbur Creek, Asotin, and Esquatzel flows exited from the basin in a channel along the northern margin of the Umatilla flow, while the Pomona and Elephant Mountain flows exited between Umtanum Ridge and Wallula Gap. The thickness of sedimentary interbeds and basalt flows indicated subsidence and/or uplift began in post-Grande Ronde time (14.5 million years before present) and continued through Saddle Mountains time (10.5 million years before present). Maximum subsidence occurred 40 kilometers (24 miles) north of Richland, Washington with an approximate rate of 25 meters (81 feet) per million years during the eruption of the basalt. Maximum uplift along the developing ridges was 70 meters (230 feet) per million years

Geochemistry and hydrodynamics of the Paradox Basin region, Utah, Colorado and New Mexico

Science.gov (United States)

Hanshaw, B.B.; Hill, G.A.

1969-01-01

The Paradox Basin region is approximately bounded by the south flank of the Uinta Basin to the north, the Uncompahgre uplift and San Juan Mountains to the east, the Four Corners structural platform to the southeast, the north rim of the Black Mesa Basin and the Grand Canyon to the south and southwest, and the Wasatch Plateau and Hurricane fault system to the west. Some of these geologic features are areas of ground-water recharge or discharge whereas others such as the Four Corners platform do not directly influence fluid movement. The aquifer systems studied were: (1) Mississippian rocks; (2) Pinkerton Trail Limestone of Wengerd and Strickland, 1954; (3) Paradox Member of the Hermosa Formation; (4) Honaker Trail Formation of Wengerd and Matheny, 1958; (5) Permian rocks. Recharge in the Paradox Basin occurs on the west flank of the San Juan Mountains and along the west side of the Uncompahgre uplift. The direction of ground-water movement in each analyzed unit is principally southwest-ward toward the topographically low outcrop areas along the Colorado River in Arizona. However, at any point in the basin, flow may be in some other direction owing to the influence of intrabasin recharge areas or local obstructions to flow, such as faults or dikes. A series of potentiometric surface maps was prepared for the five systems studied. Material used in construction of the maps included outcrop altitudes of springs and streams, drill-stem tests, water-well records, and an electric analog model of the entire basin. Many structurally and topographically high areas within the basin are above the regional potentiometric surface; recharge in these areas will drain rapidly off the high areas and adjust to the regional water level. With a few exceptions, most wells in formations above the Pennsylvanian contain fresh ( 35,000 mg/l T.D.S.) reported. Most water samples from strata below the Permian are brines of the sodium chloride type but with large amounts of calcium sulfate or

Facies analysis, depositional environments and paleoclimate of the Cretaceous Bima Formation in the Gongola Sub - Basin, Northern Benue Trough, NE Nigeria

Science.gov (United States)

Shettima, B.; Abubakar, M. B.; Kuku, A.; Haruna, A. I.

2018-01-01

Facies analysis of the Cretaceous Bima Formation in the Gongola Sub -basin of the Northern Benue Trough northeastern Nigeria indicated that the Lower Bima Member is composed of alluvial fan and braided river facies associations. The alluvial fan depositional environment dominantly consists of debris flow facies that commonly occur as matrix supported conglomerate. This facies is locally associated with grain supported conglomerate and mudstone facies, representing sieve channel and mud flow deposits respectively, and these deposits may account for the proximal alluvial fan region of the Lower Bima Member. The distal fan facies were represented by gravel-bed braided river system of probably Scot - type model. This grade into sandy braided river systems with well developed floodplains facies, forming probably at the lowermost portion of the alluvial fan depositional gradient, where it inter-fingers with basinal facies. In the Middle Bima Member, the facies architecture is dominantly suggestive of deep perennial sand-bed braided river system with thickly developed amalgamated trough crossbedded sandstone facies fining to mudstone. Couplets of shallow channels are also locally common, attesting to the varying topography of the basin. The Upper Bima Member is characterized by shallow perennial sand-bed braided river system composed of successive succession of planar and trough crossbedded sandstone facies associations, and shallower channels of the flashy ephemeral sheetflood sand - bed river systems defined by interbedded succession of small scale trough crossbedded sandstone facies and parallel laminated sandstone facies. The overall stacking pattern of the facies succession of the Bima Formation in the Gongola Sub - basin is generally thinning and fining upwards cycles, indicating scarp retreat and deposition in a relatively passive margin setting. Dominance of kaolinite in the clay mineral fraction of the Bima Formation points to predominance of humid sub - tropical

GRANNY, a data bank of chemical analyses of Laramide and younger high-silica rhyolites and granites from Colorado and north-central New Mexico

Science.gov (United States)

Steigerwald, Celia H.; Mutschler, Felix E.; Ludington, Steve

1983-01-01

GRANNY is a data bank containing information on 507 chemically analyzed Laramide or younger high-silica rhyolites and granites from Colorado and north-central New Mexico. The data were compiled from both published and unpublished sources. The data bank is designed to aid in the recognition of igneous rocks with a high exploration potential for the discovery of molybdenum (and other lithophile element) deposits. Information on source reference, geographic location, age, mineralogic and petrologic characteristics, major constituent analyses, and trace element analyses for each sample are given. The data bank is available in two formats: 1) paper- or microfiche-hardcopy, and 2) fixed format computer readable magnetic tape.

Geologic Map of the Bodie Hills Volcanic Field, California and Nevada: Anatomy of Miocene Cascade Arc Magmatism in the Western Great Basin

Science.gov (United States)

John, D. A.; du Bray, E. A.; Blakely, R. J.; Box, S.; Fleck, R. J.; Vikre, P. G.; Rytuba, J. J.; Moring, B. C.

2011-12-01

The Bodie Hills Volcanic Field (BHVF) is a >700 km2, long-lived (~9 Ma) but episodic, Miocene eruptive center in the southern part of the ancestral Cascade magmatic arc. A 1:50,000-scale geologic map based on extensive new mapping, combined with 40Ar/39Ar dates, geochemical data, and detailed gravity and aeromagnetic surveys, defines late Miocene magmatic and hydrothermal evolution of the BHVF and contrasts the subduction-related BHVF with the overlying, post-subduction, bimodal Plio-Pleistocene Aurora Volcanic Field (AVF). Important features of the BHVF include: Eruptions occurred during 3 major eruptive stages: dominantly trachyandesite stratovolcanoes (~14.7 to 12.9 Ma), mixed silicic trachyandesite, dacite, and rhyolite (~11.3 to 9.6 Ma), and dominantly silicic trachyandesite to dacite domes (~9.2 to 8.0 Ma). Small rhyolite domes were emplaced at ~6 Ma. Trachyandesitic stratovolcanoes with extensive debris flow aprons form the outer part of BHVF, whereas silicic trachyandesite to rhyolite domes are more centrally located. Geophysical data suggest that many BHVF volcanoes have shallow plutonic roots that extend to depths ≥1-2 km below the surface, and much of the Bodie Hills may be underlain by low density plutons presumably related to BHVF volcanism. BHVF rocks contain ~50 to 78% SiO2 (though few rocks have Bodie Hills at ~10 Ma, but the composition and eruptive style of volcanism continued unchanged for 2 Ma. However, kinematic data for veins and faults in mining districts suggest a change in the stress field from transtensional to extensional approximately coincident with cessation of subduction. The Bodie Hills are flanked to the east, north, and west by sedimentary basins that began to form in the late Miocene (locally >11 Ma). Fine to coarse sedimentary deposits within the BHVF include stream deposits in channels that cut across the hills and were partly filled by ~9.4 Ma Eureka Valley Tuff erupted 20 km to the northwest. Shallow dips and preservation of

Causes and possible solutions to water resource conflicts in the Okavango River Basin: The case of Angola, Namibia and Botswana

Science.gov (United States)

Mbaiwa, Joseph E.

This paper reviews available literature concerning water resources use in the Okavango River Basin (ORB). It describes a number of common arguments regarding possibilities for the emergence of violent conflict in and among Basin states, particularly those states party to the Okavango River Basin Commission (Okacom)-Angola, Botswana and Namibia. The paper presents data concerning present and future water demands and examines a number of formal, institutional steps taken by global and regional actors to facilitate sustainable development, natural resources management and peaceful cooperation in the Basin. Contrary to trends in much of the literature, the paper suggests that there is great scope for enhanced inter-state cooperation in the Basin. It argues that to achieve sustainable utilisation of water resources and avoid violent conflict in the ORB, an integrated management plan for the entire basin needs to be developed. In addition, each basin member-state should observe international and regional conventions and treaties governing the use of water resources when designing national water development projects that require the use of water from the ORB.

The Cogollo Group and the oceanic anoxic events 1a and 1b, Maracaibo basin, Venezuela

Directory of Open Access Journals (Sweden)

José Alejandro Méndez Dot

Full Text Available ABSTRACTCarbonates of Cogollo Group (Apón, Lisure and Maraca formations constitute the broader calcareous platform system originated during Aptian and Albian of Cretaceous in north-western South America, Maracaibo Basin, Venezuela. On the shallow shelf, a variety of calcareous sedimentary facies were deposited during marine transgressive and regressive cycles. Some of them developed porosity and constitute important hydrocarbon reservoirs. Due to some major marine transgressions, from early Aptian, the anoxic environment and characteristic facies of a pelagic environment moved from the outer slope and basin to the shallow shelf, during specific time intervals, favouring the sedimentation of organic matter-rich facies, which correspond to the oceanic anoxic events (OAEs 1a and 1b. The source rock of Machiques Member (Apón Formation was deposited during early Aptian OAE 1a (~ 120 Ma. The source rock of Piché Member, located at the top of the Apón Formation, was deposited during late Aptian OAE 1b (~ 113 Ma. Finally, La Luna Formation, from Cenomanian, that covers the OAE 2 (~ 93 Ma, represents the most important source rock in the Maracaibo Basin. In this way and based on sedimentological and organic geochemistry results from the determinations performed on 247 samples belonging to six cores in the Maracaibo Basin, we propose these two organic-rich levels, deposited on the shallow shelf of the Cogollo Group, as "effective source rocks", additional to La Luna Formation, with oil migration in relatively small distances to the porosity facies.

Evolution of the east-central San Jose del Cabo basin, Baja California Sur, Mexico

Science.gov (United States)

McTeague, M. S.; Umhoefer, P. J.; Schwennicke, T.; Ingle, J. C.; Cortes Martinez, M.

2006-12-01

The San Jose del Cabo basin at the southern tip of the Baja California peninsula records the early tectonic evolution of the west side of the Gulf of California. This study focused on the east central margin of the basin. The basal La Calera Formation unconformably overlies Cretaceous granite and consists of conglomerate, pebbly sandstone and conglomerate, and sandstone deposited in alluvial fans and fan-deltas. Deposition of the La Calera Formation was from ca. 9-14 Ma. The lower member of the Trinidad Formation was deposited beginning ca. 9-13 Ma and consists of sandstone, mudstone, and shelly mudstone deposited in nearshore and estuarine environments. These age estimates are based on sedimentation rates and foraminifera and coccoliths from the NN 11A nannozone (7.4 8.6 Ma, GTS 2004). The middle member of the Trinidad Formation consists of deeper water mudstones deposited by turbidity currents and suspension settling in a shelf to slope and conglomerates deposited by submarine debris flows on the shelf. The basin began earlier than previously thought. The oldest marine rocks are ca.9-13 Ma, while sedimentation on the east side began at ca. 9-14 Ma, synchronous with estimates of initiation of offset on the San Jose del Cabo fault. The Zapote fault is a down-to-the-east normal and sinistral-oblique fault that exposes a wedge of granite and older strata in the footwall to the west. The fault was active during sedimentation in the late Miocene and possibly later. The fault divides the study area into an eastern hanging wall subbasin and western footwall subbasin. The eastern subbasin formed an embayment in the eastern margin of the Cabo basin. A regional flooding surface (ca. 8 Ma) can be correlated across the fault that marks a major marine incursion. Depositional systems evolved rapidly from coarse-grained terrestrial systems to fine-grained marine and estuarine systems. The Cabo basin provides an excellent analogue for comparison with offshore basins, which are

Study of Mechanisms for Development and Strengthening of Water User Cooperatives (Case Study of Aras River Basin): Application of AHP Method

OpenAIRE

Rohallah maghabl

2014-01-01

Water user cooperatives were formed due to consideration to people's empowerment and participation in water investment and management. The purpose of this study was to investigate the mechanisms of development and strengthening of water user cooperatives in the Aras River Basin. The study population consisted of the management board members of the water user cooperatives in the Aras Basin in the year 2012. Respondents were selected by purposeful stratified sampling method. Having the data col...

The Central European Permian Basins; Rheological and structural controls on basin history and on inter-basin connectivity

NARCIS (Netherlands)

Smit, Jeroen; van Wees, Jan-Diederik; Cloetingh, Sierd

2014-01-01

We analyse the relative importance of the major crustal-scale fault zones and crustal architecture in controlling basin formation, deformation and the structural connections between basins. The North and South Permian Basins of Central Europe are usually defined by the extend of Rotliegend

Comparative Research on River Basin Management in the Sagami River Basin (Japan and the Muda River Basin (Malaysia

Directory of Open Access Journals (Sweden)

Lay Mei Sim

2018-05-01

Full Text Available In the world, river basins often interwoven into two or more states or prefectures and because of that, disputes over water are common. Nevertheless, not all shared river basins are associated with water conflicts. Rivers in Japan and Malaysia play a significant role in regional economic development. They also play a significant role as water sources for industrial, domestic, agricultural, aquaculture, hydroelectric power generation, and the environment. The research aim is to determine the similarities and differences between the Sagami and Muda River Basins in order to have a better understanding of the governance needed for effectively implementing the lessons drawn from the Sagami River Basin for improving the management of the Muda River Basin in Malaysia. This research adopts qualitative and quantitative approaches. Semi-structured interviews were held with the key stakeholders from both basins and show that Japan has endeavored to present policy efforts to accommodate the innovative approaches in the management of their water resources, including the establishment of a river basin council. In Malaysia, there is little or no stakeholder involvement in the Muda River Basin, and the water resource management is not holistic and is not integrated as it should be. Besides that, there is little or no Integrated Resources Water Management, a pre-requisite for sustainable water resources. The results from this comparative study concluded that full support and participation from public stakeholders (meaning the non-government and non-private sector stakeholders is vital for achieving sustainable water use in the Muda River Basin. Integrated Water Resources Management (IWRM approaches such as the introduction of payments for ecosystems services and the development of river basin organization in the Muda River Basin should take place in the spirit of political willingness.

Cost Effective, Ultra Sensitive Groundwater Monitoring for Site Remediation and Management

Science.gov (United States)

2015-05-01

evaporites, sandstone, gravel, conglomerate, and andesitic basalt . Closed basin; playa, alluvial fan, fluvial 600 to 10,000+ Unconfined, leaky...confined Lower unit Breccia, conglomerate, sandstone, siltstone, and local basaltic to rhyolitic flows and pyroclastic rocks. Alluvial fan, fluvial...with large volumes of groundwater. Three of the cartridges additionally protected by glass fiber filters (Acrodisc AP-4523; Pall GmbH, Dreieich, GE

Simulation of the mulltizones clastic reservoir: A case study of Upper Qishn Clastic Member, Masila Basin-Yemen

Science.gov (United States)

Khamis, Mohamed; Marta, Ebrahim Bin; Al Natifi, Ali; Fattah, Khaled Abdel; Lashin, Aref

2017-06-01

The Upper Qishn Clastic Member is one of the main oil-bearing reservoirs that are located at Masila Basin-Yemen. It produces oil from many zones with different reservoir properties. The aim of this study is to simulate and model the Qishn sandstone reservoir to provide more understanding of its properties. The available, core plugs, petrophysical, PVT, pressure and production datasets, as well as the seismic structural and geologic information, are all integrated and used in the simulation process. Eclipse simulator was used as a powerful tool for reservoir modeling. A simplified approach based on a pseudo steady-state productivity index and a material balance relationship between the aquifer pressure and the cumulative influx, is applied. The petrophysical properties of the Qishn sandstone reservoir are mainly investigated based on the well logging and core plug analyses. Three reservoir zones of good hydrocarbon potentiality are indicated and named from above to below as S1A, S1C and S2. Among of these zones, the S1A zone attains the best petrophysical and reservoir quality properties. It has an average hydrocarbon saturation of more than 65%, high effective porosity up to 20% and good permeability record (66 mD). The reservoir structure is represented by faulted anticline at the middle of the study with a down going decrease in geometry from S1A zone to S2 zone. It is limited by NE-SW and E-W bounding faults, with a weak aquifer connection from the east. The analysis of pressure and PVT data has revealed that the reservoir fluid type is dead oil with very low gas liquid ratio (GLR). The simulation results indicate heterogeneous reservoir associated with weak aquifer, supported by high initial water saturation and high water cut. Initial oil in place is estimated to be around 628 MM BBL, however, the oil recovery during the period of production is very low (<10%) because of the high water cut due to the fractures associated with many faults. Hence, secondary and

The timing and origin of pre- and post-caldera volcanism associated with the Mesa Falls Tuff, Yellowstone Plateau volcanic field

Science.gov (United States)

Stelten, Mark E.; Champion, Duane E.; Kuntz, Mel A.

2018-01-01

We present new sanidine 40Ar/39Ar ages and paleomagnetic data for pre- and post-caldera rhyolites from the second volcanic cycle of the Yellowstone Plateau volcanic field, which culminated in the caldera-forming eruption of the Mesa Falls Tuff at ca. 1.3 Ma. These data allow for a detailed reconstruction of the eruptive history of the second volcanic cycle and provide new insights into the petrogenesis of rhyolite domes and flows erupted during this time period. 40Ar/39Ar age data for the biotite-bearing Bishop Mountain flow demonstrate that it erupted approximately 150 kyr prior to the Mesa Falls Tuff. Integrating 40Ar/39Ar ages and paleomagnetic data for the post-caldera Island Park rhyolite domes suggests that these five crystal-rich rhyolites erupted over a centuries-long time interval at 1.2905 ± 0.0020 Ma (2σ). The biotite-bearing Moonshine Mountain rhyolite dome was originally thought to be the downfaulted vent dome for the pre-caldera Bishop Mountain flow due to their similar petrographic and oxygen isotope characteristics, but new 40Ar/39Ar dating suggest that it erupted near contemporaneously with the Island Park rhyolite domes at 1.2931 ± 0.0018 Ma (2σ) and is a post-caldera eruption. Despite their similar eruption ages, the Island Park rhyolite domes and the Moonshine Mountain dome are chemically and petrographically distinct and are not derived from the same source. Integrating these new data with field relations and existing geochemical data, we present a petrogenetic model for the formation of the post-Mesa Falls Tuff rhyolites. Renewed influx of basaltic and/or silicic recharge magma into the crust at 1.2905 ± 0.0020 Ma led to [1] the formation of the Island Park rhyolite domes from the source region that earlier produced the Mesa Falls Tuff and [2] the formation of Moonshine Mountain dome from the source region that earlier produced the biotite-bearing Bishop Mountain flow. These magmas were stored in the crust for less than a few thousand

The community Noah land surface model with multiparameterization options (Noah-MP): 2. Evaluation over global river basins

KAUST Repository

Yang, Zong-Liang

2011-06-24

The augmented Noah land surface model described in the first part of the two-part series was evaluated here over global river basins. Across various climate zones, global-scale tests can reveal a model\\'s weaknesses and strengths that a local-scale testing cannot. In addition, global-scale tests are more challenging than local- and catchment-scale tests. Given constant model parameters (e. g., runoff parameters) across global river basins, global-scale tests are more stringent. We assessed model performance against various satellite and ground-based observations over global river basins through six experiments that mimic a transition from the original Noah LSM to the fully augmented version. The model shows transitional improvements in modeling runoff, soil moisture, snow, and skin temperature, despite considerable increase in computational time by the fully augmented Noah-MP version compared to the original Noah LSM. The dynamic vegetation model favorably captures seasonal and spatial variability of leaf area index and green vegetation fraction. We also conducted 36 ensemble experiments with 36 combinations of optional schemes for runoff, leaf dynamics, stomatal resistance, and the β factor. Runoff schemes play a dominant and different role in controlling soil moisture and its relationship with evapotranspiration compared to ecological processes such as β the factor, vegetation dynamics, and stomatal resistance. The 36-member ensemble mean of runoff performs better than any single member over the world\\'s 50 largest river basins, suggesting a great potential of land-based ensemble simulations for climate prediction. Copyright © 2011 by the American Geophysical Union.

Chromophoric dissolved organic matter (CDOM) variability in Barataria Basin using excitation-emission matrix (EEM) fluorescence and parallel factor analysis (PARAFAC).

Science.gov (United States)

Singh, Shatrughan; D'Sa, Eurico J; Swenson, Erick M

2010-07-15

Chromophoric dissolved organic matter (CDOM) variability in Barataria Basin, Louisiana, USA,was examined by excitation emission matrix (EEM) fluorescence combined with parallel factor analysis (PARAFAC). CDOM optical properties of absorption and fluorescence at 355nm along an axial transect (36 stations) during March, April, and May 2008 showed an increasing trend from the marine end member to the upper basin with mean CDOM absorption of 11.06 + or - 5.01, 10.05 + or - 4.23, 11.67 + or - 6.03 (m(-)(1)) and fluorescence 0.80 + or - 0.37, 0.78 + or - 0.39, 0.75 + or - 0.51 (RU), respectively. PARAFAC analysis identified two terrestrial humic-like (component 1 and 2), one non-humic like (component 3), and one soil derived humic acid like (component 4) components. The spatial variation of the components showed an increasing trend from station 1 (near the mouth of basin) to station 36 (end member of bay; upper basin). Deviations from this increasing trend were observed at a bayou channel with very high chlorophyll-a concentrations especially for component 3 in May 2008 that suggested autochthonous production of CDOM. The variability of components with salinity indicated conservative mixing along the middle part of the transect. Component 1 and 4 were found to be relatively constant, while components 2 and 3 revealed an inverse relationship for the sampling period. Total organic carbon showed increasing trend for each of the components. An increase in humification and a decrease in fluorescence indices along the transect indicated an increase in terrestrial derived organic matter and reduced microbial activity from lower to upper basin. The use of these indices along with PARAFAC results improved dissolved organic matter characterization in the Barataria Basin. Copyright 2010 Elsevier B.V. All rights reserved.

Drainage basins features and hydrological behaviour river Minateda basin

International Nuclear Information System (INIS)

Alonso-Sarria, F.

1991-01-01

Nine basin variables (shape, size and topology) have been analyzed in four small basins with non-permanent run off (SE of Spain). These geomorphological variables have been selected for their high correlation with the Instantaneous unit hydrograph parameters. It is shown that the variables can change from one small basin to another within a very short area; because of it, generalizations about the behaviour of the run off are not possible. In conclusion, it is stated that the variations in geomorphological aspects between different basins, caused mainly by geological constraints, are a very important factor to be controlled in a study of geoecological change derived from climatic change

RESERVES IN WESTERN BASINS PART IV: WIND RIVER BASIN

Energy Technology Data Exchange (ETDEWEB)

Robert Caldwell

1998-04-01

Vast quantities of natural gas are entrapped within various tight formations in the Rocky Mountain area. This report seeks to quantify what proportion of that resource can be considered recoverable under today's technological and economic conditions and discusses factors controlling recovery. The ultimate goal of this project is to encourage development of tight gas reserves by industry through reducing the technical and economic risks of locating, drilling and completing commercial tight gas wells. This report is the fourth in a series and focuses on the Wind River Basin located in west central Wyoming. The first three reports presented analyses of the tight gas reserves and resources in the Greater Green River Basin (Scotia, 1993), Piceance Basin (Scotia, 1995) and the Uinta Basin (Scotia, 1995). Since each report is a stand-alone document, duplication of language will exist where common aspects are discussed. This study, and the previous three, describe basin-centered gas deposits (Masters, 1979) which contain vast quantities of natural gas entrapped in low permeability (tight), overpressured sandstones occupying a central basin location. Such deposits are generally continuous and are not conventionally trapped by a structural or stratigraphic seal. Rather, the tight character of the reservoirs prevents rapid migration of the gas, and where rates of gas generation exceed rates of escape, an overpressured basin-centered gas deposit results (Spencer, 1987). Since the temperature is a primary controlling factor for the onset and rate of gas generation, these deposits exist in the deeper, central parts of a basin where temperatures generally exceed 200 F and drill depths exceed 8,000 feet. The abbreviation OPT (overpressured tight) is used when referring to sandstone reservoirs that comprise the basin-centered gas deposit. Because the gas resources trapped in this setting are so large, they represent an important source of future gas supply, prompting studies

Stratigraphy, age, and depositional setting of the Miocene Barstow Formation at Harvard Hill, central Mojave Desert, California

Science.gov (United States)

Leslie, Shannon R.; Miller, David M.; Wooden, Joseph L.; Vazquez, Jorge A.

2010-01-01

New detailed geologic mapping and geochronology of the Barstow Formation at Harvard Hill, 30 km east of Barstow, CA, help to constrain Miocene paleogeography and tectonics of the central Mojave Desert. A northern strand of the Quaternary ENE-striking, sinistral Manix fault divides the Barstow Formation at Harvard Hill into two distinct lithologic assemblages. Strata north of the fault consist of: a green rhyolitic tuff, informally named the Shamrock tuff; lacustrine sandstone; partially silicified thin-bedded to massive limestone; and alluvial sandstone to pebble conglomerate. Strata south of the fault consist of: lacustrine siltstone and sandstone; a rhyolitic tuff dated at 19.1 Ma (U-Pb); rock-avalanche breccia deposits; partially silicified well-bedded to massive limestone; and alluvial sandstone and conglomerate. Our U-Pb zircon dating of the Shamrock tuff by SHRIMP-RG yields a peak probability age of 18.7 ± 0.1 Ma. Distinctive outcrop characteristics, mineralogy, remanent magnetization, and zircon geochemistry (Th/U) suggest that the Shamrock tuff represents a lacustrine facies of the regionally extensive Peach Spring Tuff (PST). Here we compare zircon age and geochemical analyses from the Shamrock tuff with those of the PST at Stoddard Wash and provide new insight into the age of zircon crystallization in the PST rhyolite. Results of our field studies show that Miocene strata at Harvard Hill mostly accumulated in a lacustrine environment, although depositional environments varied from a relatively deep lake to a very shallow lake or even onshore setting. Rock-avalanche breccias and alluvial deposits near the base of the exposed section indicate proximity to a steep basin margin and detrital studies suggest a southern source for coarse-grained deposits; therefore, we may infer a southern basin-margin setting at Harvard Hill during the early Miocene. Our geochronology demonstrates that deposition of the Barstow Formation at Harvard Hill extended from before

A new combined nanoSIMS and continuous-flow IRMS approach to measure hydrogen isotopes from water in hydrated rhyolitic glass

Science.gov (United States)

Gatti, E.; Kitchen, N.; Newman, S.; Guan, Y.; Westgate, J.; Pearce, N. J. G.; Nikolic, D.; Eiler, J. M.

2016-12-01

The hydrogen-isotope value of water of hydration (or secondary water) preserved in rhyolitic glasses may provide significant insights regarding the climate at the time of their deposition and the impact of super-eruptions upon the environment. However, the ability of the glass to retain the environmental D/H isotopic signal after hydration needs to be tested, since modifications to the D/H systematics may result from the continuous exchange of D/H with the atmosphere or condensed water after initial glass hydration. Ideal geological archives to test whether the glass retains its original hydrogen signal are sediments in natural waters and ice cores, which preserve tephra in constrained horizons that can be independently isotopically characterised. However, tephra in marine and fresh water sediments and ice cores are often present in concentrations of the order of 1000 grains/cm3 (IRMS methods require much more material ( 100-500 mg) and therefore cannot be applied. We present here a new integrated nanoSIMS and continuous flow IRMS approach to understand how water is distributed within single glass grains (diffusion profiles), quantify the time of hydration of young (Holocene) and old (Miocene) already well-characterised rhyolitic glasses, and measure the D/H ratio of the hydration water on single grains and bulk material consisting of only approximately 0.1-1 mg. The IRMS method measures the absolute abundance of hydrogen released from the sample by continuous-flow mass spectrometry. Current data indicates that the method can accurately measure a hydrogen signal from a rock sample containing at least 400 nanomoles of H2, corresponding to 70 µg of water, which translates to 1 mg of hydrous glass (>3 wt%) or 15 mg of dry ( 0.5 wt%) obsidian chips. The method can be improved by reducing the blank to IRMS method will be compared to sub-micron mapping of single-grains using a high-resolution ion microprobe, the CAMECA NanoSIMS 50L, in the Microanalysis Center for

Zircon U-Pb geochronology, Sm-Nd and Pb-Pb isotope systematics of Ediacaran post-collisional high-silica Acampamento Velho volcanism at the Tupanci area, NW of the Sul-Rio-Grandense Shield, Brazil

Energy Technology Data Exchange (ETDEWEB)

Sommer, Carlos Augusto; Leitzke, Felipe Padilha; Lima, Evandro Fernandes de; Barreto, Carla Joana Santos; Matté, Vinicius; Philipp, Ruy Paulo; Conceição, Rommulo Vieira, E-mail: casommer@sinos.net, E-mail: eflgeologo@gmail.com, E-mail: ruy.philipp@ufrgs.br, E-mail: rommulo.conceicao@ufrgs.br [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Instituto de Geociências; Lafon, Jean Michel, E-mail: lafonjm@ufpa.br [Universidade Federal do Pará (UFPA), Belém, PA (Brazil). Laboratório de Geologia Isotópica; Basei, Miguel Ângelo Stipp, E-mail: baseimas@usp.br [Universidade de São Paulo (CPGeo/IGc/USP), São Paulo, SP (Brazil)

2017-10-15

We present new U-Pb zircon ages and Sm-Nd-Pb isotopic data for volcanic and hypabyssal acid rocks from the northernmost exposure of the Acampamento Velho Formation in the NW portion of the Sul-Rio-Grandense Shield, Brazil. The first volcanic episode, grouped in the high-Ti rhyolites from the Tupanci hill, shows age of 579 ± 5.6 Ma, which is in agreement with the post-collisional Acampamento Velho Formation volcanism in the Bom Jardim Group of the Camaquã Basin. A poorly constrained age of 558+/- 39Ma was obtained for rhyolites from the low-Ti group at the Picados Hill, which may indicate a younger acid volcanism, or a greater time span for the volcanism of the Acampamento Velho Formation in southernmost Brazil. Regarding magmatic sources, Sm/Nd isotopic data coupled to Pb isotopes and a review of trace element geochemistry indicate different amounts of Paleoproterozoic (Dom Feliciano, Pinheiro Machado Suite) to Neoproterozoic (Rio Vacacaí terrane) lower crust melting. Our data, coupled with literature data, contribute to a better understanding of the stratigraphic evolution for the Neoproterozoic post-collisional volcanic successions of the Camaquã Basin in the Sul-Rio-Grandense Shield. (author)

The Crownpoint and Churchrock uranium deposits, San Juan Basin, New Mexico: An ISL mining perspective

International Nuclear Information System (INIS)

McCarn, D.W.

2001-01-01

The Crownpoint and Churchrock uranium deposits, San Juan Basin, New Mexico are currently being developed by Uranium Resources, Inc. (URI) and its subsidiary Hydro Resources, Inc. (HRI) with an anticipated start-up in 1998. Both deposits will be developed using advanced in situ leach (ISL) mining techniques. URI/HRI currently has about 14,583 t U (37.834 million pounds U 3 O 8 ) of estimated recoverable reserves at Crownpoint and Churchrock. at a cost less than $39/kg U ($15/lb U 3 O 8 ). The uranium endowment of the San Juan Basin is the largest of any province in the USA. In March, 1997, a Final Environmental Impact Statement (FEIS) for the Crownpoint and Churchrock sites was completed by the Nuclear Regulatory Commission which recommends the issuance of an operating license. The FEIS is the culmination of a 9 year effort to license and develop the deposits. The Westwater Canyon Member of the Jurassic Morrison Formation is an arkosic, fine to coarse grained sandstone bounded by near basinwide confining clays deposited in a wet alluvial fan environment within the San Juan Basin. The primary, trend-ore deposits are hosted by the Westwater Canyon Member as humate-rich, syngenetic tabular deposits which were subsequently remobilized into roll fronts. Since deposition in the Jurassic, two phases of remobilization have occurred in the basin causing the formation of in situ leach amenable monometallic uranium rolls free of organic debris. Following in situ mining, ground water restoration of the Crownpoint and Churchrock mines is required to provide a water quality consistent with pre-mining baseline conditions. The development of in situ mining offers an environmentally sound and cost-effective method for uranium extraction. URI/HRI anticipates a production of 385-1,156 Tonnes U/year (1-3 million pounds U 3 O 8 ) from the New Mexico properties. (author)

Paleo relief study of insular shelf electric sounding in Amarillo level basin Rivera distric in Uruguay

International Nuclear Information System (INIS)

Perrin, J.

1983-01-01

In the framework of the Uranium project the geophysical team composed by BRGM and DINAMIGE members have carried out a study of insular shelf morphology. It was a sedimentary basin level in the middle of the Isla Cristalina. The following topics were developed: geographical location, geologic framework, developed works and materials, methods and results

Contrasting basin architecture and rifting style of the Vøring Basin, offshore mid-Norway and the Faroe-Shetland Basin, offshore United Kingdom

Science.gov (United States)

Schöpfer, Kateřina; Hinsch, Ralph

2017-04-01

The Vøring and the Faroe-Shetland basins are offshore deep sedimentary basins which are situated on the outer continental margin of the northeast Atlantic Ocean. Both basins are underlain by thinned continental crust whose structure is still debated. In particular the nature of the lower continental crust and the origin of high velocity bodies located at the base of the lower crust are a subject of discussion in recent literature. Regional interpretation of 2D and 3D seismic reflection data, combined with well data, suggest that both basins share several common features: (i) Pre-Cretaceous faults that are distributed across the entire basin width. (ii) Geometries of pre-Jurassic strata reflecting at least two extensional phases. (iii) Three common rift phases, Late Jurassic, Campanian-Maastrichtian and Palaeocene. (iv) Large pre-Cretaceous fault blocks that are buried by several kilometres of Cretaceous and Cenozoic strata. (iii). (v) Latest Cretaceous/Palaeocene inversion. (vi) Occurrence of partial mantle serpentinization during Early Cretaceous times, as proposed by other studies, seems improbable. The detailed analysis of the data, however, revealed significant differences between the two basins: (i) The Faroe-Shetland Basin was a fault-controlled basin during the Late Jurassic but also the Late Cretaceous extensional phase. In contrast, the Vøring Basin is dominated by the late Jurassic rifting and subsequent thermal subsidence. It exhibits only minor Late Cretaceous faults that are localised above intra-basinal and marginal highs. In addition, the Cretaceous strata in the Vøring Basin are folded. (ii) In the Vøring Basin, the locus of Late Cretaceous rifting shifted westwards, affecting mainly the western basin margin, whereas in the Faroe-Shetland Basin Late Cretaceous rifting was localised in the same area as the Late Jurassic phase, hence masking the original Jurassic geometries. (iii) Devono-Carboniferous and Aptian/Albian to Cenomanian rift phases

Tectonostratigraphic history of the Neogene Maimará basin, Northwest Argentina

Science.gov (United States)

Galli, Claudia I.; Coira, Beatriz L.; Alonso, Ricardo N.; Iglesia Llanos, María P.; Prezzi, Claudia B.; Kay, Suzanne Mahlburg

2016-12-01

This paper presents the tectonostratigraphic evolution of the Maimará Basin and explores the relationship between the clastic sediments and pyroclastic deposits in the basin and the evolution of the adjacent orogeny and magmatic arc. The sedimentary facies in this part of the basin include, in ascending order, an ephemeral fluvial system, a deep braided fluvial system and a medial to distal ephemeral fluvial system. We interpret that Maimará Formation accumulated in a basin that has developed two stages of accumulation. Stage 1 extended from 7 to 6.4 Ma and included accelerated tectonic uplift in the source areas, and it corresponds to the ephemeral fluvial system deposits. Stage 2, which extended from 6.4 to 4.8 Ma, corresponds to a tectonically quiescent period and included the development of the deep braided fluvial system deposits. The contact between the Maimará and Tilcara formations is always characterized by a regional unconformity and, in the study area, also shows pronounced erosion. Rare earth element and other chemical characteristics of the tuff intervals in the Maimará Formation fall into two distinct groups suggesting the tuffs were erupted from two distinct late Miocene source regions. The first and most abundant group has characteristics that best match tuffs erupted from the Guacha, Pacana and Pastos Grandes calderas, which are located 200 and 230 km west of the study area at 22º-23º30‧S latitude. The members the second group are chemically most similar to the Merihuaca Ignimbrite from the Cerro Galán caldera 290 km south-southwest of the studied section. The distinctive geochemical characteristics are excellent tools to reconstruct the stratigraphic evolution of the Neogene Maimará basin from 6.4 to 4.8 Ma.

Using a map-based assesment tool for the development of cost-effective WFD river basin action programmes in a changing climate

DEFF Research Database (Denmark)

Kaspersen, Bjarke Stoltze; Vammen Jacobsen, Torsten; Brian Butts, Michael

2016-01-01

For the 2nd and 3rd river basin management cycles (2015–2027) of the Water Framework Directive (WFD), EU Member States are required to fully integrate climate change into the process of river basin management planning (RBMP). Complying with the main WFD objective of achieving ‘good ecological...... Basin in the north east of Denmark. The tool facilitates assessments of the application of agri-environmental measures that are targeted towards low retention agricultural areas, where limited or no surface and subsurface N reduction takes place. Effects of climate change on nitrate leaching were...... evaluated using the dynamic agro-ecosystem model ‘Daisy’. Results show that nitrate leaching rates increase by approx. 25% under current management practices. This impact outweighs the expected total N reduction effect of Baseline 2015 and the first RBMP in the case study river basin. The particular Po...

Detailed measured sections, cross sections, and paleogeographic reconstructions of the upper cretaceous and lower tertiary nonmarine interval, Wind River Basin, Wyoming: Chapter 10 in Petroleum systems and geologic assessment of oil and gas resources in the Wind River Basin Province, Wyoming

Science.gov (United States)

Johnson, Ronald C.

2007-01-01

Detailed measured sections and regional stratigraphic cross sections are used to reconstruct facies maps and interpret paleogeographic settings for the interval from the base of Upper Cretaceous Mesaverde Formation to top of lower member of the Paleocene Fort Union Formation in the Wind River Basin, Wyoming. The Mesaverde Formation spans the time during which the Upper Cretaceous seaway retreated eastward out of central Wyoming in Campanian time and the initial stages of the Lewis transgression in earliest Maastrichtian time. This retreat stalled for a considerable period of time during deposition of the lower part of the Mesaverde, creating a thick buildup of marginal marine sandstones and coaly coastal plain deposits across the western part of the basin. The Lewis sea transgressed into the northeast part of Wind River Basin, beginning in early Maastrichtian time during deposition of the Teapot Sandstone Member of the Mesaverde Formation. The Meeteetse Formation, which overlies the Teapot, was deposited in a poorly-drained coastal plain setting southwest of the Lewis seaway. The Lewis seaway, at maximum transgression, covered much of the northeast half of the Wind River Basin area but was clearly deflected around the present site of the Wind River Range, southwest of the basin, providing the first direct evidence of Laramide uplift on that range. Uplift of the Wind River Range continued during deposition of the overlying Maastrichtian Lance Formation. The Granite Mountains south of the basin also became a positive feature during this time. A rapidly subsiding trough during the Maastrichtian time formed near the presentday trough of the Wind River Basin in which more than 6,000 feet of Lance was deposited. The development of this trough appears to have begun before the adjacent Owl Creek Mountains to the north started to rise; however, a muddy facies in the upper part of Lance in the deep subsurface, just to the south, might be interpreted to indicate that the

Fragmentation, nucleation and migration of crystals and bubbles in the Bishop Tuff rhyolitic magma

Energy Technology Data Exchange (ETDEWEB)

Gualda, G.; Cook, D.L.; Chopra, R.; Qin, L.; Anderson, A.T.; Rivers, M. (UC)

2010-12-07

The Bishop Tuff (USA) is a large-volume, high-silica pyroclastic rhyolite. Five pumice clasts from three early stratigraphic units were studied. Size distributions were obtained using three approaches: (1) crushing, sieving and winnowing (reliable for crystals >100 {micro}m); (2) microscopy of 1 mm{sup 3} fragments (preferable for crystals <100 {micro}m); and (3) computerised X-ray microtomography of {approx}1 cm{sup 3} pumice pieces. Phenocryst fragments coated with glass are common, and the size distributions for all crystals are concave-upward, indicating that crystal fragmentation is an important magmatic process. Three groups are recognised, characterised by: (1) high-density (0.759-0.902 g cm{sup -3}), high-crystal content (14.4-15.3 wt.%) and abundant large crystals (>800 {micro}m); concave-downward size distributions for whole crystals indicate late-stage growth with limited nucleation, compatible with the slow cooling of a large, gas-saturated, stably stratified magma body; (2) low-density (0.499 g cm{sup -3}), low-crystal content (6.63 wt.%) and few large crystals; the approximately linear size distribution reveals that nucleation was locally important, perhaps close to the walls; and (3) intermediate characteristics in all respects. The volumetric fraction of bubbles inversely correlates with the number of large crystals. This is incompatible with isobaric closed-system crystallisation, but can be explained by sinking of large crystals and rise of bubbles in the magma.

Strength and deformation mechanisms of rhyolitic glass at lower seismogenic zone conditions

Science.gov (United States)

Proctor, B.; Lockner, D. A.; Lowenstern, J. B.; Beeler, N. M.

2017-12-01

Although its relevance to coseismic earthquake source properties is still debated, frictional melting and the production of quenched glass called pseudotachylyte is a recurring process in some earthquake source regions. To investigate how glassy materials affect the post- and interseismic- strength and stability of faults, rhyolitic obsidian gouges were sheared under dry and wet conditions from 200 °C to 300 °C at effective normal stresses up to 200 MPa. Velocity-stepping and slide-hold slide tests were performed for up to three days. Dry glass gouges exhibited a brittle rheology at all conditions tested, exhibiting friction values and microstructures consistent with siliciclastic materials. Likewise, wet glass gouges at 200 °C exhibited a brittle rheology. In contrast, wet gouges at 300 °C transitioned from brittle sliding to linear-viscous (Newtonian) flow at strain rates < 3x10-4 s-1, indicating melt-like behavior well below the equilibrium melting temperature. The melt ranged from 2.1x1011 to 2.6x1012 Pa-s. The molten gouges transitioned back to glass when strain rates were increased, which, in some cases, promoted extreme strengthening. The molten gouges were fully welded with rod-shaped microlites rotated and boudinaged into the flow direction. There was very little evidence for nucleation of new phases within the glass or metasomatic alteration. Fourier transform infrared spectroscopy along with electron backscatter imaging demonstrate that hydration of the glass by diffusion of pore water was the dominant process reducing the viscosity and promoting melt flow. As much as 5 wt% water diffused into the nominally anhydrous glass. These results may provide insight into postseismic-slip behaviors and challenge some interpretations of fault kinematics which assume pseudotachylyte formation and flow is solely coseismic.

Site evaluation for U.S. Bureau of Mines experimental oil-shale mine, Piceance Creek basin, Rio Blanco County, Colorado

Science.gov (United States)

Ege, John R.; Leavesley, G.H.; Steele, G.S.; Weeks, J.B.

1978-01-01

The U.S. Geological Survey is cooperating with the U.S. Bureau of Mines in the selection of a site for a shaft and experimental mine to be constructed in the Piceance Creek basin, Rio Blanco County, Colo. The Piceance Creek basin, an asymmetric, northwest-trending large structural downwarp, is located approximately 40 km (25 mi) west of the town of Meeker in Rio Blanco County, Colo. The oil-shale, dawsonite, nahcolite, and halite deposits of the Piceance Creek basin occur in the lacustrine Green River Formation of Eocene age. In the basin the Green River Formation comprises three members. In ascending order, they are the Douglas Creek, the Garden Gulch, and the Parachute Creek Members, Four sites are presented for consideration and evaluated on geology and hydrology with respect to shale-oil economics. Evaluated criteria include: (1) stratigraphy, (2) size of site, (3) oil-shale yield, (4) representative quantities of the saline minerals dawsonite and nahcolite, which must be present with a minimum amount of halite, (5) thickness of a 'leached' saline zone, (6) geologic structure, (7) engineering characteristics of rock, (8) representative surface and ground-water conditions, with emphasis on waste disposal and dewatering, and (9) environmental considerations. Serious construction and support problems are anticipated in sinking a deep shaft in the Piceance Creek basin. The two major concerns will be dealing with incompetent rock and large inflow of saline ground water, particularly in the leached zone. Engineering support problems will include stabilizing and hardening the rock from which a certain amount of ground water has been removed. The relative suitability of the four potential oil-shale experimental shaft sites in the Piceance Creek basin has been considered on the basis of all available geologic, hydrologic, and engineering data; site 2 is preferred to sites 1, 3, and 4, The units in this report are presented in the form: metric (English). Both units of

Qingshankou-Putaohua/Shaertu and Jurassic Coal-Denglouku/Nongan total petroleum systems in the Songliao Basin, China

Science.gov (United States)

Ryder, Robert T.; Qiang, Jin; McCabe, Peter J.; Nuccio, Vito F.; Persits, Felix

2003-01-01

The Qingshankou-Putaohua/Shaertu petroleum system involves the generation of oil and gas from a mature pod of lacustrine source rock near the center of the Songliao Basin in northeastern China. The primary source rock is the Lower Cretaceous Qingshankou Formation, and a secondary source rock is Member 1 of the Lower Cretaceous Nenjiang Formation. The most productive of six sandstone reservoirs are the Putaohua reservoir (Member 1 of the Lower Cretaceous Yaojia Formation) and the Shaertu reservoir (Members 2 and 3 of the Yaojia Formation and Member 1 of the Nenjiang Formation). Most oil and associated gas generated from the Qingshankou Formation and Nenjiang Formation (Member 1) are trapped in large faulted anticlines, fault blocks, and faulted anticlinal noses in combination with facies-change and (or) diagenetic stratigraphic traps. Two assessment units are defined in the petroleum system: (1) an anticlinal assessment unit; and (2) a subtle-traps assessment unit consisting of (a) anticlinal noses in combination with fault or stratigraphic traps, (b) stratigraphic traps, and (c) unconventional reservoirs. Undiscovered conventional oil and gas resources are expected in both assessment units in small (5?10 million barrels of oil; 30?60 billion ft3 gas) and medium (10?25 million barrels of oil; 60?150 billion ft3 of gas) fields. Also, undiscovered conventional oil and gas resources are expected in several large fields (25?73 million barrels of oil; 150?173 billion ft3 of gas). The Jurassic coal?Dengloukou/Nongan petroleum system involves the generation of natural gas from multiple pods of mature source rock in graben structures at the base of the Songliao Basin. Sandstone and conglomeratic sandstone in the Lower Cretaceous Denglouku Formation and the Lower Cretaceous Quantou Formation are the major reservoir rocks. Most of the known natural gas is trapped in anticlines, anticlinal noses, and fault blocks. This petroleum system is largely unexplored in comparison to

The public component of sea basins radiological safety

International Nuclear Information System (INIS)

Agutov, V.I.

2003-01-01

Full text: The sea is the key and essential element of the basin although the bigger share of the basin consists of the river ecosystems. The classical theory of sustainable basin development implies that the one of the main indicator of sustainable development is the river ecosystem biodiversity and especially the sturgeon kind of fish with long life cycle. The fish biodiversity and stocks of valuable fish were totally destroyed. One of the most serious causes for that was the inadequate water policy aimed at the construction of the river dam complexes and the construction of the huge water reservoirs. These water reservoirs were used for different purposes, but the main danger is coming from their usage as nuclear power plant cooling ponds. The wide public has received the opportunity to learn about the ecological danger of such objects. The modern Russian society doesn't fully believe to the results of monitoring by state agencies. In order to propel these activities the creation of non-governmental ecological organizations is needed within the all the key elements of river ecosystems. The information skeleton throughout the whole basin needed for successful and effective functioning of these organizations can be constructed only under the condition of having good and modern means of communication such as electronic ones (e-mail, Internet) and publishing of own newspapers and bulletins. Our regional non-governmental organization has created already such a network within the Don and accepting existing local organizations as members. The activities on the creation of the same networks have been already induced in the Volga and Ural rivers basins. Now the networks are more or less shaped and we start equipping the local NGOs with radiation detection devices of 'Inspector'class for measuring the beta and gamma radiation. Having the needed experts and specialists the independent networked organizations will be able not only to monitor the radiological situation

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

Science.gov (United States)

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

2004-01-01

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

3-D basin modelling of the Paris Basin: diagenetic and hydrogeologic implications

International Nuclear Information System (INIS)

Violette, S.; Goncalves, J.; Jost, A.; Marsily, G. de

2004-01-01

A 3-D basin model of the Paris basin is presented in order to simulate through geological times fluid, heat and solute fluxes. This study emphasizes: i) the contribution of basin models to the quantitative hydrodynamic understanding of behaviour of the basin over geological times; ii) the additional use of Atmospheric General Circulation model (AGCM) to provide palaeo-climatic boundaries for a coupled flow and mass transfer modelling, constrained by geochemical and isotopic tracers and; iii) the integration of different types of data (qualitative and quantitative) to better constrain the simulations. Firstly, in a genetic way, basin model is used to reproduce geological, physical and chemical processes occurring in the course of the 248 My evolution of the Paris basin that ought to explain the present-day hydraulic properties at the regional scale. As basin codes try to reproduce some of these phenomena, they should be able to give a plausible idea of the regional-scale permeability distribution of the multi-layered system, of the pre-industrial hydrodynamic conditions within the aquifers and of the diagenesis timing and type of hydrodynamic processes involved. Secondly, climate records archived in the Paris basin groundwater suggest that climate and morphological features have an impact on the hydrogeological processes, particularly during the last 5 My. An Atmospheric General Circulation model is used with a refined spatial resolution centred on the Paris basin to reproduce the climate for the present, the Last Glacial Maximum (21 ky) and the middle Pliocene (3 My). These climates will be prescribed, through forcing functions to the hydrological code with the main objective of understanding the way aquifers and aquitards react under different climate conditions, the period and the duration of these effects. Finally, the Paris basin has been studied for a number of years by different scientific communities, thus a large amount of data has been collected. By

Analysis of gravity anomalies in the Ulleung Basin (East Sea/Sea of Japan) and its implications for the crustal structure of rift-dominated back-arc basin

Science.gov (United States)

Kim, Yoon-Mi; Lee, Sang-Mook

2018-01-01

The Ulleung Basin (UB), one of three major basins in the East Sea/Sea of Japan, is considered to represent a continental-rifting end-member of back-arc basin system, but is much less understood compared to the nearby Yamato Basin (YB) and Japan Basin (JB). This study examines the gravity anomalies of the UB since the variation in crustal thickness can provide important insights on the mode of extension during basin opening. Our analysis shows that the Moho depth (from the sea surface) varies from 16 km at the basin center to 22 km at the edges. However, within the central part of the basin, the crustal thickness (not including sediment) is more or less the same (10-12 km), by varying only about 10-20% of the total thickness, contrary to the previous suggestions. Our finding of anomalous but uniformly thick crust is consistent with the recent seismic results from the YB (14 km on average). A mantle residual gravity anomaly high (∼20 mGal) exists in the northeastern part of the UB. This feature is interpreted as the location of maximum extension (slightly thinner crust by ∼1 km). Together with another moderate gravity high to the southwest, the two anomalies form a NNE-SSW line, which corresponds to the direction of the major tectonic structures of the Korean Peninsula. We argue that the a massive magmatic emplacement took place extensively in the lower crust of the UB during the opening, significantly increasing its overall thickness to almost twice as that of the JB where a mid-ocean-ridge style seafloor spreading occurred. Two important post-opening processes took place after the formation of uniformly thick crust: post-rift volcanic intrusions in the north, especially in its northeast sections but had little effect on the residual gravity anomaly itself, and the deflection of crust in response to differential sediment loading towards the south, producing the median high in the basement in response to the flexural bending. We also conducted a simple test to

Paleogene Vertebrate Paleontology, Geology and Remote Sensing in the Wind River Basin

Science.gov (United States)

Stucky, R. K.; Krishtalka, L.

1985-01-01

Biostratigraphic and lithostratigraphic studies were used to correlate different events in the geologic evolution of the northeastern part of the Wind River Basin and have suggested several conclusions. Laterally equivalent exposures of the Lysite member from Cedar Ridge to Bridger Creek show a gradation in lithology from interbedded boulder conglomerates and sandstones to interbedded lenticular sandstones and mudstones to interbedded carbonaceous shales, coals and tabular sandstones. This gradation suggests a shift from alluvial fan to braided stream to paludal or lacustrine sedimentary environments during the late early Eocene. The Lysite and Lost Cabin members of the Wind River Formation are in fault contact in the Bridger Creek area and may intertongue to the east along Cedar Ridge. Ways in which remote sensing could be used in these studies are discussed.

Fishes of the Taquari-Antas river basin (Patos Lagoon basin, southern Brazil

Directory of Open Access Journals (Sweden)

FG. Becker

Full Text Available The aquatic habitats of the Taquari-Antas river basin (in the Patos Lagoon basin, southern Brazil are under marked environmental transformation because of river damming for hydropower production. In order to provide an information baseline on the fish fauna of the Taquari-Antas basin, we provide a comprehensive survey of fish species based on primary and secondary data. We found 5,299 valid records of fish species in the basin, representing 119 species and 519 sampling sites. There are 13 non-native species, six of which are native to other Neotropical river basins. About 24% of the total native species are still lacking a taxonomic description at the species level. Three native long-distance migratory species were recorded (Leporinus obtusidens, Prochilodus lineatus, Salminus brasiliensis, as well as two potential mid-distance migrators (Parapimelodus nigribarbis and Pimelodus pintado. Although there is only one officially endangered species in the basin (S. brasiliensis, restricted range species (21.7% of total species should be considered in conservation efforts.

K-Basins design guidelines

International Nuclear Information System (INIS)

Roe, N.R.; Mills, W.C.

1995-06-01

The purpose of the design guidelines is to enable SNF and K Basin personnel to complete fuel and sludge removal, and basin water mitigation by providing engineering guidance for equipment design for the fuel basin, facility modifications (upgrades), remote tools, and new processes. It is not intended to be a purchase order reference for vendors. The document identifies materials, methods, and components that work at K Basins; it also Provides design input and a technical review process to facilitate project interfaces with operations in K Basins. This document is intended to compliment other engineering documentation used at K Basins and throughout the Spent Nuclear Fuel Project. Significant provisions, which are incorporated, include portions of the following: General Design Criteria (DOE 1989), Standard Engineering Practices (WHC-CM-6-1), Engineering Practices Guidelines (WHC 1994b), Hanford Plant Standards (DOE-RL 1989), Safety Analysis Manual (WHC-CM-4-46), and Radiological Design Guide (WHC 1994f). Documents (requirements) essential to the engineering design projects at K Basins are referenced in the guidelines

Curimata punctata, a new uniquely pigmented species of curimatid from the Marowijne river basin of Surinam and French Guiana (Pisces, Characiformes)

NARCIS (Netherlands)

Vari, Richard P.; Nijssen, Han

1986-01-01

A new species of curimatid characiform, Curimata punctata, from the Marowijne River basin of Surinam and French Guiana is described and illustrated. The distinctive pattern of three to six dark midlateral spots on the body distinguishes the species from all other members of the family.

Intra- and inter-basin mercury comparisons: Importance of basin scale and time-weighted methylmercury estimates

International Nuclear Information System (INIS)

Bradley, Paul M.; Journey, Celeste A.; Brigham, Mark E.; Burns, Douglas A.; Button, Daniel T.; Riva-Murray, Karen

2013-01-01

To assess inter-comparability of fluvial mercury (Hg) observations at substantially different scales, Hg concentrations, yields, and bivariate-relations were evaluated at nested-basin locations in the Edisto River, South Carolina and Hudson River, New York. Differences between scales were observed for filtered methylmercury (FMeHg) in the Edisto (attributed to wetland coverage differences) but not in the Hudson. Total mercury (THg) concentrations and bivariate-relationships did not vary substantially with scale in either basin. Combining results of this and a previously published multi-basin study, fish Hg correlated strongly with sampled water FMeHg concentration (ρ = 0.78; p = 0.003) and annual FMeHg basin yield (ρ = 0.66; p = 0.026). Improved correlation (ρ = 0.88; p < 0.0001) was achieved with time-weighted mean annual FMeHg concentrations estimated from basin-specific LOADEST models and daily streamflow. Results suggest reasonable scalability and inter-comparability for different basin sizes if wetland area or related MeHg-source-area metrics are considered. - Highlights: ► National scale mercury assessments integrate small scale study results. ► Basin scale differences and representativeness of fluvial mercury samples are concerns. ► Wetland area, not basin size, predicts inter-basin methylmercury variability. ► Time-weighted methylmercury estimates improve the prediction of mercury in basin fish. - Fluvial methylmercury concentration correlates with wetland area not basin scale and time-weighted estimates better predict basin top predator mercury than discrete sample estimates.

Pressure Changes before and after Explosive Rhyolitic Bomb Ejection at Chaiten, Chile Recorded By Water Diffusion Profiles Around Tuffisite Veins

Science.gov (United States)

Tuffen, H.; McGowan, E.; Castro, J. M.; Berlo, K.; James, M. R.; Owen, J.; Schipper, C. I.; Wadsworth, F. B.; Saubin, E.; Wehbe, K.

2014-12-01

The recent rhyolitic eruptions at Chaitén and Cordón Caulle have provided valuable new insights into the relationship between explosive and effusive activity, and the gas escape mechanisms that permit rapid effusion of degassed lava[1,2]. Bombs ejected during mixed explosive-effusive activity host spectacular tuffisite veins cutting both dense obsidian (Fig 1a) and highly-expanded pumice. Tuffisite veins are ash-filled fracture networks that act as ephemeral permeable pathways for gas escape in shallow conduits and lava domes. Previous studies have revealed water depletion adjacent to tuffisite veins, leading to models of fracture-triggered pressure release[2] and estimates of gas escape timescales[2,3]. We have characterised water diffusion profiles from a new suite of tuffisite-bearing Chaitén bombs, using synchrotron-source FTIR at the Diamond Light Source, Oxford, UK. Unexpectedly, one exceptionally large tuffisite vein, which is 30 mm thick (Fig. 1a, b) is mantled by zones of strong water enrichment, which enclose the usual narrow depletion zones immediately adjacent to the vein (Fig. 1c). Consistent results from different branches of this vein (Fig. 1b) indicate a similar history. The plausible range of diffusion model solutions points towards ~2-4 hours of vein pressurisation, followed by a brief pre-quench period of lower pressure conditions. In our model the vein opened during a period of overpressure at the lava dome base, sustained by gas influx from a deeper catchment extending hundreds of metres into the upper conduit. Overpressure culminated in violent bomb ejection, after which vein pressure decreased due to gas leakage to the atmosphere through the incompletely welded vein, as observed in rhyolitic bombs from Cordón Caulle (Fig. 1d). Commonly-seen water depletion zones[2,3] may therefore merely record post-fragmentation degassing. However, the enrichment zone points towards the type of deep pressurisation associated with cycles of tilt and

Preliminary study of the favorability for uranium in selected areas in the Basin and Range Province, Nevada

International Nuclear Information System (INIS)

Cupp, G.M.; Leedom, S.H.; Mitchell, T.P.; Kiloh, K.D.; Horton, R.C.

1977-10-01

Six uranium areas in Nevada were examined in a reconnaissance fashion to determine their favorability for uranium deposits. The favorable areas are: Virgin Valley, Humboldt County; northern Reese River Valley, Lander County; East Walker River, Lyon County; and Coaldale, Esmeralda County. Areas judged to be unfavorable are: Carol ''R'' prospect, Garfield Hills, Mineral County; and Meadow Valley (Panaca), Lincoln County. In the Virgin Valley area, the Canyon Rhyolite Formation contains as much as 27 ppM U 3 O 8 and is an excellent source rock. Uranium deposits in the underlying Virgin Valley Formation are small, but larger deposits may exist. The northern portion of the Reese River Valley contains several small uranium deposits but none of mineable grade or size. Rhyolitic volcanic rocks in the area contain above-average amounts of uranium, and larger deposits may lie beneath these potential source rocks. The East Walker River area may be part of a larger uranium province. Intrusive and extrusive rocks in the area contain above-average amounts of uranium, and low-grade supergene deposits were found. Large areas of potential source rocks and host rocks, and two small uranium deposits, were found in the Coaldale area. Many rhyolite plugs were also found. The Carol ''R'' prospect is an isolated uranium occurrence in Tertiary lacustrine rocks. Uranium deposits in Meadow Valley are in the Panaca Formation, a Pliocene lacustrine formation of varied lithology. The uranium deposits are small and low grade. It is unlikely that large-grade deposits will be found in this area

Proximal stratigraphy and event sequence of the c. 5600 cal. yr BP Whakatane rhyolite eruption episode from Haroharo volcano, Okataina Volcanic Centre, New Zealand

International Nuclear Information System (INIS)

Kobayashi, T.; Nairn, I.; Smith, V.; Shane, P.

2005-01-01

The c. 5600 cal. yr BP Whakatane eruption episode consisted of a sequence of intracaldera rhyolite eruptions from at least five vents spread over 11 km of the Haroharo linear vent zone within Okataina Volcanic Centre. Initial vent-opening eruptions from the Haroharo vent produced coarse lithic clast 'blast beds' and pyroclastic density currents surges). These were immediately followed by eruption of very mobile pumiceous pyroclastic surges from the Makatiti vent 6 km to the southwest. Major plinian eruptions from the Makatiti vent then dispersed Whakatane Tephra pumice fall deposits (bulk volume c. 6 km 3 ) across the northeastern North Island while smaller explosive eruptions produced pyroclastic flows and falls from the Haroharo-Rotokohu vents and at the Pararoa vent on the caldera rim 11 km northeast from Makatiti. The pyroclastic eruptions at all vents were followed by the extrusion of lava flows and domes; extruded lava volumes ranged from 0.03 km 3 for the Pararoa dome to 7.5 km 3 for the Makatiti-Tapahoro lava flows and domes. Minor variations in whole rock and glass chemistry show that the three main vent areas each tapped a slightly different high-silica rhyolite magma. About 10 km 3 of M-type magma was erupted from the Makatiti-Tapahoro vents; c. 1.3 km 3 of H-type magma from the Haroharo-Rotokohu vents, and 0.04 km 3 of P-type magma from the Pararoa vent. There are no significant weathering or erosional breaks within the Whakatane eruptive sequence, which suggests that all Whakatane eruptions occurred within a short time interval. However, extrusion of the Haroharo dome within the Makatiti pyroclastic eruption sequence suggests a duration of c. 2 yr for the main pyroclastic eruption phase. Emplacement of the following voluminous (7.5 km 3 ) lavas from the Makatiti-Tapahoro vents would have occurred over >10 yr at the c. 10-20 m 3 /s inferred extrusion rates. (author). 19 refs., 16 figs., 7 tabs

Isotopic dating of the post-Alpine Neogene volcanism in the Betic Cordilleras, southern Spain

Energy Technology Data Exchange (ETDEWEB)

Nobel, F A; Rondeel, H E [Amsterdam Univ. (Netherlands). Geologisch Inst.; Andriessen, P A.M.; Hebeda, E H; Priem, H N.A. [Laboratorium voor Isotopen-Geologie, Amsterdam (Netherlands)

1981-06-01

The post-Alpine lamproitic volcanism in the Prebetic of the External Zone of the Betic Cordilleras of southern Spain is dated at 7.6-7.2 Ma by the K-Ar data from two richterites, two sanidines, a phlogopite and a whole-rock, and the fission-track analysis of an apatite. Biotite from a lava of the rhyolitic-dacitic suite in the post-orogenic Vera basin of the Internal Zone produces the same age. Phlogopite from a lamproitic (veritic) subvolcanic body in the Vera basin yields an age of about 8.6 Ma; as lavas belonging to the veritic suite reportedly overlie Late Messinian sediments, pointing to an age of less than about 5 Ma, this type of volcanism in the Vera basin must have been active over several million years.

Hydrothermal alteration of a rhyolitic hyaloclastite from Ponza Island, Italy

Science.gov (United States)

Ylagan, Robert F.; Altaner, Stephen P.; Pozzuoli, Antonio

1996-12-01

A rhyolitic hyaloclastite from Ponza island, Italy, has been hydrothermally altered producing four distinct alteration zones based on XRD and field textures: (1) non-pervasive argillic zone; (2) propylitic zone; (3) silicic zone; and (4) sericitic zone. The unaltered hyaloclastite is a volcanic breccia with clasts of vesiculated obsidian in a matrix of predominantly pumice lapilli. Incomplete alteration of the hyaloclastite resulted in the non pervasive argillic zone, characterized by smectite and disordered opal-CT. Obsidian clasts, some pumice lapilli, and pyrogenic plagioclase and biotite are unaltered. Smectite has an irregular flakey morphology, although euhedral particles are occasionally observed. The propylitic zone is characterized by mixed-layer illite/smectite (I/S) with 10 to 85% illite (I), mordenite, opal-C and authigenic K-feldspar (akspar). The matrix of the hyaloclastite is completely altered and obsidian clasts are silicified; however, plagioclase and biotite phenocrysts remain unaltered. Flakey I/S replaces pumice, and mordenite, akspar and silica line and fill pores. I/S particles are composed predominantly of subequant plates and euhedral laths. The silicic zone is characterized by highly illitic I/S with ≥ 90% I, quartz, akspar and occasional albite. In this zone the matrix and clasts are completely altered, and pyrogenic plagioclase shows significant alteration. Illitic I/S has a euhedral lath-like morphology. In the sericitic zone the hyaloclastite altered primarily to illitic I/S with ≥ 66% I, quartz, and minor akspar and pyrite. Clay minerals completely replace pyrogenic feldspars and little evidence remains of the original hyaloclastite texture. Unlike other zones, illitic I/S is fibrous and pure illite samples are composed of euhedral laths and hexagonal plates. The temperatures of hydrothermal alteration likely ranged from 30 to 90 °C for the argillic zone, from 110 to 160 °C for the propylitic zone, from 160 to 270 °C for the

A framework model for water-sharing among co-basin states of a river basin

Science.gov (United States)

Garg, N. K.; Azad, Shambhu

2018-05-01

A new framework model is presented in this study for sharing of water in a river basin using certain governing variables, in an effort to enhance the objectivity for a reasonable and equitable allocation of water among co-basin states. The governing variables were normalised to reduce the governing variables of different co-basin states of a river basin on same scale. In the absence of objective methods for evaluating the weights to be assigned to co-basin states for water allocation, a framework was conceptualised and formulated to determine the normalised weighting factors of different co-basin states as a function of the governing variables. The water allocation to any co-basin state had been assumed to be proportional to its struggle for equity, which in turn was assumed to be a function of the normalised discontent, satisfaction, and weighting factors of each co-basin state. System dynamics was used effectively to represent and solve the proposed model formulation. The proposed model was successfully applied to the Vamsadhara river basin located in the South-Eastern part of India, and a sensitivity analysis of the proposed model parameters was carried out to prove its robustness in terms of the proposed model convergence and validity over the broad spectrum values of the proposed model parameters. The solution converged quickly to a final allocation of 1444 million cubic metre (MCM) in the case of the Odisha co-basin state, and to 1067 MCM for the Andhra Pradesh co-basin state. The sensitivity analysis showed that the proposed model's allocation varied from 1584 MCM to 1336 MCM for Odisha state and from 927 to 1175 MCM for Andhra, depending upon the importance weights given to the governing variables for the calculation of the weighting factors. Thus, the proposed model was found to be very flexible to explore various policy options to arrive at a decision in a water sharing problem. It can therefore be effectively applied to any trans-boundary problem where

Contrasting Permo - Carboniferous Evolution of Resita and Sirinia - Presacina Basins (South Carpathians, Romania); an overview.

Science.gov (United States)

Tatu, M.; Seghedi, I.; Nutu, L. M.; Nicolae, I.

2009-04-01

rarely lens-like fresh water limestone. During the Permian in the Resita basin the volcanic activity was absent. In the Sirinia - Presacina basin the Lower Permian deposits are characterized by huge volcanic and volcano - sedimentary assemblages inter-fingering with red beds detritic formations. The Permian volcanism in the Sirinia - Presacina basin is dominant rhyolitic and started in subaqueous conditions. Early subaqueous domes (as isolated or as clusters) and lava flows led to the generation at their margins of huge volume of hyaloclastic breccias that turn unstable forming marginally turbiditic hyaloclastite aprons. In the Sirinia zone, where the magmas get to the shallower waters and/or to subaerial, the volcanic activity turned progressively to be explosive, generating phreatomagmatic eruptions. The result of this activity is up to several hundred meters of various deposits represented by pyroclastic flow (dominantly non-welded and welded ignimbrites), pyroclastic surge and fall out, all rich in accretionary lapilli. At the distal, marginal part of the volcanic environs the epiclastic, mostly lahar deposits are dominating, sometimes including layers of fallout deposits with accretionary lapilli that suggest their contemporaneous deposition. In the eastern part of Sirinia - Presacina basin (Cucuiova Hill) the presence of basalts as sills in the Permian sandstone deposits may be a sign of bimodal magmatic activity. As in the some of the Central Europe Permian basins the volcanic activity from Sirinia - Presacina basin is related to intra-basinal active faults and in particular with the intersection of fault systems having a pull-apart features (e.g. Stollhofen et al., 1999). The most important factor which was controlled the Permo - Carboniferous complex evolution of the Western and Central Europe was tectonic. The continue convergence between Laurasia and Gondwana during the Upper Carboniferous - Lower Permian (Ziegler, 1990) was generated a conjugate dextral

Basins in ARC-continental collisions

Science.gov (United States)

Draut, Amy E.; Clift, Peter D.; Busby, Cathy; Azor, Antonio

2012-01-01

Arc-continent collisions occur commonly in the plate-tectonic cycle and result in rapidly formed and rapidly collapsing orogens, often spanning just 5-15 My. Growth of continental masses through arc-continent collision is widely thought to be a major process governing the structural and geochemical evolution of the continental crust over geologic time. Collisions of intra-oceanic arcs with passive continental margins (a situation in which the arc, on the upper plate, faces the continent) involve a substantially different geometry than collisions of intra-oceanic arcs with active continental margins (a situation requiring more than one convergence zone and in which the arc, on the lower plate, backs into the continent), with variable preservation potential for basins in each case. Substantial differences also occur between trench and forearc evolution in tectonically erosive versus tectonically accreting margins, both before and after collision. We examine the evolution of trenches, trench-slope basins, forearc basins, intra-arc basins, and backarc basins during arc-continent collision. The preservation potential of trench-slope basins is low; in collision they are rapidly uplifted and eroded, and at erosive margins they are progressively destroyed by subduction erosion. Post-collisional preservation of trench sediment and trench-slope basins is biased toward margins that were tectonically accreting for a substantial length of time before collision. Forearc basins in erosive margins are usually floored by strong lithosphere and may survive collision with a passive margin, sometimes continuing sedimentation throughout collision and orogeny. The low flexural rigidity of intra-arc basins makes them deep and, if preserved, potentially long records of arc and collisional tectonism. Backarc basins, in contrast, are typically subducted and their sediment either lost or preserved only as fragments in melange sequences. A substantial proportion of the sediment derived from

Formaldehyde as a carbon and electron shuttle between autotroph and heterotroph populations in acidic hydrothermal vents of Norris Geyser Basin, Yellowstone National Park

Energy Technology Data Exchange (ETDEWEB)

Moran, James J.; Whitmore, Laura M.; Isern, Nancy G.; Romine, Margaret F.; Riha, Krystin M.; Inskeep, William P.; Kreuzer, Helen W.

2016-03-19

The Norris Geyser Basin in Yellowstone National Park contains a large number of hydrothermal systems, which host microbial populations supported by primary productivity associated with a suite of chemolithotrophic metabolisms. We demonstrate that Metallosphaera yellowstonesis MK1, a facultative autotrophic archaeon isolated from a hyperthermal acidic hydrous ferric oxide (HFO) spring in Norris Geyser Basin, excretes formaldehyde during autotrophic growth. To determine the fate of formaldehyde in this low organic carbon environment, we incubated native microbial mat (containing M. yellowstonensis) from a HFO spring with 13C-formaldehyde. Isotopic analysis of incubation-derived CO2 and biomass showed that formaldehyde was both oxidized and assimilated by members of the community. Autotrophy, formaldehyde oxidation, and formaldehyde assimilation displayed different sensitivities to chemical inhibitors, suggesting that distinct sub-populations in the mat selectively perform these functions. Our results demonstrate that electrons originally resulting from iron oxidation can energetically fuel autotrophic carbon fixation and associated formaldehyde excretion, and that formaldehyde is both oxidized and assimilated by different organisms within the native microbial community. Thus, formaldehyde can effectively act as a carbon and electron shuttle connecting the autotrophic, iron oxidizing members with associated heterotrophic members in the HFO community.

Magmatic emulsion texture formed by mixing during extrusion, Rauðafell composite complex, Breiðdalur volcano, eastern Iceland

DEFF Research Database (Denmark)

Charreteur, Gilles; Tegner, Christian

2013-01-01

The Rauoafell composite complex is part of the Neogene Breiodalur volcano, eastern Iceland and is composed of a composite feeder dyke, a vent structure and a composite flow. The two end-members of the composite complex are rhyolite and basalt, and both are rich in plagioclase macrocrysts: bytowni...

Superposition of tectonic structures leading elongated intramontane basin: the Alhabia basin (Internal Zones, Betic Cordillera)

Science.gov (United States)

Martínez-Martos, Manuel; Galindo-Zaldivar, Jesús; Martínez-Moreno, Francisco José; Calvo-Rayo, Raquel; Sanz de Galdeano, Carlos

2017-10-01

The relief of the Betic Cordillera was formed since the late Serravallian inducing the development of intramontane basins. The Alhabia basin, situated in the central part of the Internal Zones, is located at the intersection of the Alpujarran Corridor, the Tabernas basin, both trending E-W, and the NW-SE oriented Gádor-Almería basin. The geometry of the basin has been constrained by new gravity data. The basin is limited to the North by the Sierra de Filabres and Sierra Nevada antiforms that started to develop in Serravallian times under N-S shortening and to the south by Sierra Alhamilla and Sierra de Gádor antiforms. Plate convergence in the region rotated counter-clockwise in Tortonian times favouring the formation of E-W dextral faults. In this setting, NE-SW extension, orthogonal to the shortening direction, was accommodated by normal faults on the SW edge of Sierra Alhamilla. The Alhabia basin shows a cross-shaped depocentre in the zone of synform and fault intersection. This field example serves to constrain recent counter-clockwise stress rotation during the latest stages of Neogene-Quaternary basin evolution in the Betic Cordillera Internal Zones and underlines the importance of studying the basins' deep structure and its relation with the tectonic structures interactions.

Geothermometry, geochronology, and mass transfer associated with hydrothermal alteration of a rhyolitic hyaloclastite from Ponza Island, Italy

Science.gov (United States)

Altaner, S.P.; Ylagan, R.F.; Savin, S.M.; Aronson, J.L.; Belkin, H.E.; Pozzuoli, A.

2003-01-01

A rhyolitic hyaloclastite from Ponza Island, Italy, was hydrothermally altered, producing four distinct alteration zones based on X-ray diffraction mineralogy and field textures: (1) nonpervasive argillic zone; (2) propylitic zone; (3) silicic zone; and (4) sericitic zone. The unaltered hyaloclastite is volcanic breccia with clasts of vesiculated obsidian in a matrix of predominantly pumice lapilli. Incomplete alteration of the hyaloclastite resulted in the nonpervasive argillic zone, characterized by smectite and disordered opal-CT. The other three zones exhibit more complete alteration of the hyaloclastite. The propylitic zone is characterized by mixed-layer illite-smectite (I-S) with 10 to 85% I, mordenite, opal-C, and authigenic K-feldspar (akspar). The silicic zone is characterized by I-S with ???90% I, pure illite, quartz, akspar, and occasional albite. The sericitic zone consists primarily of I-S with ???66% I, pure illite, quartz, and minor akspar and pyrite. K/Ar dates of I-S indicate hydrothermal alteration occurred at 3.38 ?? 0.08 Ma. Oxygen isotope compositions of I-S systematically decrease from zones 1 to 4. In the argillic zone, smectite has ??18 O values of 21.7 to 22.0??? and I-S from the propylitic, silicic, and sericitic zones ranges from 14.5 to 16.3???, 12.5 to 14.0???, and 8.6 to 11.9???, respectively. ??18 O values for quartz from the silicic and sericitic zones range from 12.6 to 15.9???. By use of isotope fractionation equations and data from authigenic quartz-hosted primary fluid inclusions, alteration temperatures ranged from 50 to 65 ??C for the argillic zone, 85 to 125 ??C for the propylitic zone, 110 to 210 ??C for the silicic zone, and 145 to 225 ??C for the sericitic zone. Fluid inclusion data and calculated ??18 O water values indicate that hydrothermal fluids were seawater dominated. Mass-transfer calculations indicate that hydrothermal alteration proceeded in a relatively open chemical system and alteration in the sericitic zone

Geologic and climatic controls on streamflow generation processes in a complex eogenetic karst basin

Science.gov (United States)

Vibhava, F.; Graham, W. D.; Maxwell, R. M.

2012-12-01

Streamflow at any given location and time is representative of surface and subsurface contributions from various sources. The ability to fully identify the factors controlling these contributions is key to successfully understanding the transport of contaminants through the system. In this study we developed a fully integrated 3D surface water-groundwater-land surface model, PARFLOW, to evaluate geologic and climatic controls on streamflow generation processes in a complex eogenetic karst basin in North Central Florida. In addition to traditional model evaluation criterion, such as comparing field observations to model simulated streamflow and groundwater elevations, we quantitatively evaluated the model's predictions of surface-groundwater interactions over space and time using a suite of binary end-member mixing models that were developed using observed specific conductivity differences among surface and groundwater sources throughout the domain. Analysis of model predictions showed that geologic heterogeneity exerts a strong control on both streamflow generation processes and land atmospheric fluxes in this watershed. In the upper basin, where the karst aquifer is overlain by a thick confining layer, approximately 92% of streamflow is "young" event flow, produced by near stream rainfall. Throughout the upper basin the confining layer produces a persistent high surficial water table which results in high evapotranspiration, low groundwater recharge and thus negligible "inter-event" streamflow. In the lower basin, where the karst aquifer is unconfined, deeper water tables result in less evapotranspiration. Thus, over 80% of the streamflow is "old" subsurface flow produced by diffuse infiltration through the epikarst throughout the lower basin, and all surface contributions to streamflow originate in the upper confined basin. Climatic variability provides a secondary control on surface-subsurface and land-atmosphere fluxes, producing significant seasonal and

Characterization of juvenile pyroclasts from the Kos Plateau Tuff (Aegean Arc): insights into the eruptive dynamics of a large rhyolitic eruption

Science.gov (United States)

Bouvet de Maisonneuve, Caroline; Bachmann, Olivier; Burgisser, Alain

2009-08-01

Silicic pumices formed during explosive volcanic eruptions are faithful recorders of the state of the magma in the conduit, close to or at the fragmentation level. We have characterized four types of pumices from the non-welded rhyolitic Kos Plateau Tuff, which erupted 161,000 years ago in the East Aegean Arc, Greece. The dominant type of pumice (>90 vol.%) shows highly elongated tubular vesicles. These tube pumices occur throughout the eruption. Less common pumice types include: (1) “frothy” pumice (highly porous with large, sub-rounded vesicles), which form 5-10 vol.% of the coarsest pyroclastic flow deposits, (2) dominantly “microvesicular” and systematically crystal-poor pumices, which are found in early erupted, fine-grained pyroclastic flow units, and are characterized by many small (<50 μm in diameter) vesicles and few mm-sized, irregular voids, (3) grey or banded pumices, indicating the interaction between the rhyolite and a more mafic magma, which are found throughout the eruption sequence and display highly irregular bubble shapes. Except for the grey-banded pumices, all three other types are compositionally identical and were generated synchronously as they are found in the same pyroclastic units. They, therefore, record different conditions in the volcanic conduit leading to variable bubble nucleation, growth and coalescence. A total of 74 pumice samples have been characterized using thin section observation, SEM imagery, porosimetry, and permeametry. We show that the four pumice types have distinct total and connected porosity, tortuosity and permeability. Grey-banded pumices show large variations in petrophysical characteristics as a response to mingling of two different magmas. The microvesicular, crystal-poor, pumices have a bimodal bubble size distribution, interpreted as reflecting an early heterogeneous bubble nucleation event followed by homogeneous bubble nucleation close to fragmentation. Finally, the significant differences in

Operational Hydrologic Forecasts in the Columbia River Basin

Science.gov (United States)

Shrestha, K. Y.; Curry, J. A.; Webster, P. J.; Toma, V. E.; Jelinek, M.

2013-12-01

The Columbia River Basin (CRB) covers an area of ~670,000 km2 and stretches across parts of seven U.S. states and one Canadian province. The basin is subject to a variable climate, and moisture stored in snowpack during the winter is typically released in spring and early summer. These releases contribute to rapid increases in flow. A number of impoundments have been constructed on the Columbia River main stem and its tributaries for the purposes of flood control, navigation, irrigation, recreation, and hydropower. Storage reservoirs allow water managers to adjust natural flow patterns to benefit water and energy demands. In the past decade, the complexity of water resource management issues in the basin has amplified the importance of streamflow forecasting. Medium-range (1-10 day) numerical weather forecasts of precipitation and temperature can be used to drive hydrological models. In this work, probabilistic meteorological variables from the European Center for Medium Range Weather Forecasting (ECMWF) are used to force the Variable Infiltration Capacity (VIC) model. Soil textures were obtained from FAO data; vegetation types / land cover information from UMD land cover data; stream networks from USGS HYDRO1k; and elevations from CGIAR version 4 SRTM data. The surface energy balance in 0.25° (~25 km) cells is closed through an iterative process operating at a 6 hour timestep. Output fluxes from a number of cells in the basin are combined through one-dimensional flow routing predicated on assumptions of linearity and time invariance. These combinations lead to daily mean streamflow estimates at key locations throughout the basin. This framework is suitable for ingesting daily numerical weather prediction data, and was calibrated using USGS mean daily streamflow data at the Dalles Dam (TDA). Operational streamflow forecasts in the CRB have been active since October 2012. These are 'naturalized' or unregulated forecasts. In 2013, increases of ~2600 m3/s (~48% of

SimBasin: serious gaming for integrated decision-making in the Magdalena-Cauca basin

Science.gov (United States)

Craven, Joanne; Angarita, Hector; Corzo, Gerald

2016-04-01

The Magdalena-Cauca macrobasin covers 24% of the land area of Colombia, and provides more than half of the country's economic potential. The basin is also home a large proportion of Colombia's biodiversity. These conflicting demands have led to problems in the basin, including a dramatic fall in fish populations, additional flooding (such as the severe nationwide floods caused by the La Niña phenomenon in 2011), and habitat loss. It is generally believed that the solution to these conflicts is to manage the basin in a more integrated way, and bridge the gaps between decision-makers in different sectors and scientists. To this end, inter-ministerial agreements are being formulated and a decision support system is being developed by The Nature Conservancy Colombia. To engage stakeholders in this process SimBasin, a "serious game", has been developed. It is intended to act as a catalyst for bringing stakeholders together, an illustration of the uncertainties, relationships and feedbacks in the basin, and an accessible introduction to modelling and decision support for non-experts. During the game, groups of participants are led through a 30 year future development of the basin, during which they take decisions about the development of the basin and see the impacts on four different sectors: agriculture, hydropower, flood risk, and environment. These impacts are displayed through seven indicators, which players should try to maintain above critical thresholds. To communicate the effects of uncertainty and climate variability, players see the actual value of the indicator and also a band of possible values, so they can see if their decisions have actually reduced risk or if they just "got lucky". The game works as a layer on top of a WEAP water resources model of the basin, adapted from a basin-wide model already created, so the fictional game basin is conceptually similar to the Magdalena-Cauca basin. The game is freely available online, and new applications are being

Relating petroleum system and play development to basin evolution: West African South Atlantic basins

NARCIS (Netherlands)

Beglinger, S.E.; Doust, H.; Cloetingh, S.A.P.L.

2012-01-01

Sedimentary basins can be classified according to their structural genesis and evolutionary history and the latter can be linked to petroleumsystem and playdevelopment. We propose an approach in which we use the established concepts in a new way: breaking basins down into their natural basin cycle

River Basin Scale Management and Governance: Competing Interests for Western Water

Science.gov (United States)

Lindquist, Eric

2015-04-01

regarded as a highly desirable amenity and ecosystem service provider for the region. It is also a very polarizing construct as diverse interests engaged in basin decision making do not share the same values, perceptions, and constituents. Although regulatory and jurisdictional decision making is in the hands of a few agencies (US Army Corps of Engineers and US Bureau of Reclamation, for example), it is estimated that up to 300 different interests and groups are engaged in using, supporting, and attempting to influence the decisions associated with the Boise River and its myriad uses. Building on previous river basin governance research in the US and Europe, the work presented here is framed on a policy network approach, and focuses on four main factors of the BRB: the type of stakeholder and their perceptions of the BRB as a resource or amenity, role(s) of the stakeholder in the network, interactions between network members and the public, and the role of science, uncertainty and the impact of climate change. This contribution addresses many of the question raised in the HS5.7 call for abstracts and will be of interest to a wide audience.

System of prediction and warning of floods in the water basin of Struma/ Strymonas River

International Nuclear Information System (INIS)

Mimides, Theologos; Rizos, Spyros; Soulis, Kostas; Dimitrov, Dobri

2004-01-01

Struma is collecting waters from four countries: Bulgaria, Serbia, FYROM and Greece. Most of its basin area is located in Bulgaria and Greece, while the upper part of its basin is in Bulgaria. There are important hydro technical structures just below the Bulgarian-Greek border, and the floods generated in the Bulgarian part of the basin could significantly affect the security of those structures and their operational rules. That is why several years ago a project related to flood warning at Struma/ Strymonas river basin was formulated and its first phase was completed in 2000. The main objective of the project was to demonstrate the principal possibility for issuing reliable warnings for hazardous flood events with sufficient lead-time to organize flood mitigation measures. The project implementation team included various scientists from the Agricultural University of Athens-Greece (leader), from the Center of Remote Sensing, Bristol University-UK, and from the National Institute of Meteorology and Hydrology of Sofia - Bulgaria. The work program of the first project phase included a range of activities implemented by the Bulgarian and Greek team members, coordinated by the Agricultural University of Athens. Among the activities of the Project are included: a) a preliminary model for peak flood hydrographs and specifications of an early warning system, b) a real time flood forecasting by routing flood hydrographs through the system of the river and Kerkini lake, c) thematic maps of vegetation and land cover derived by satellite remote sensing, d) satellite snow monitoring in the basin, e) an adaptation of the Alladin Weather Forecast Model at the hydrological basin and scaling of the Crocus Snow Model at a preliminary stage, and f) development of a geo environmental recording system.(Author)

K Basin safety analysis

International Nuclear Information System (INIS)

Porten, D.R.; Crowe, R.D.

1994-01-01

The purpose of this accident safety analysis is to document in detail, analyses whose results were reported in summary form in the K Basins Safety Analysis Report WHC-SD-SNF-SAR-001. The safety analysis addressed the potential for release of radioactive and non-radioactive hazardous material located in the K Basins and their supporting facilities. The safety analysis covers the hazards associated with normal K Basin fuel storage and handling operations, fuel encapsulation, sludge encapsulation, and canister clean-up and disposal. After a review of the Criticality Safety Evaluation of the K Basin activities, the following postulated events were evaluated: Crane failure and casks dropped into loadout pit; Design basis earthquake; Hypothetical loss of basin water accident analysis; Combustion of uranium fuel following dryout; Crane failure and cask dropped onto floor of transfer area; Spent ion exchange shipment for burial; Hydrogen deflagration in ion exchange modules and filters; Release of Chlorine; Power availability and reliability; and Ashfall

Melo carboniferous basin

International Nuclear Information System (INIS)

Flossdarf, A.

1988-01-01

This report is about of the Melo carboniferous basin which limits are: in the South the large and high Tupambae hill, in the west the Paraiso hill and the river mountains, in the North Yaguaron river basin to Candidata in Rio Grande del Sur in Brazil.

Geology and stratigraphy of the San Lorenzo Tezonco deep well and its correlation to surrounding ranges, Mexico Basin

Science.gov (United States)

Arce, J. L.; Layer, P. W.; Morales-Casique, E.; Benowitz, J.

2014-12-01

The San Lorenzo Tezonco deep well stratigraphy records intense episodic volcanic activity in the Mexico Basin and surroundings during the past 20 Ma. The 2008-m deep lithological column is dominated by volcanic material, either as lava flows or pyroclastic deposits (97%), and only the upper most 70 m are composed of lacustrine deposits (3%). Based on geochronology and geochemistry, the lower part of the drill core is represented by rocks correlating to the Tepoztlán Formation (876-2008 m deep) that vary in composition from basaltic-andesite to rhyolite, and ages ranging from 13 to 21.2 Ma. On the surface this formation outcrops near the towns of Malinalco and Tepoztlán, ~43 km south of the deep well. Between depths of 581 and 875 m, volcanic rocks were recovered and are interpreted as lavas from the Sierra de las Cruces that vary in composition from andesite to dacite and range in age from 0.9 Ma to 5 Ma. Additionally, we documented rocks belonging to the Xochitepec Formation, outcropping around Xochimilco, in the Mexico City, with ages ranging from 1.2 and 1.7 Ma, in contrast with the Oligocene age proposed in previous works for these rocks. These new ages plus the chemical composition data, allow us to correlate the Xochitepec rocks with Sierra de las Cruces. Upward in the drill core (510-580 m) there are andesitic rocks that correlate with the 0.25 Ma Cerro de la Estrella volcanic center. The last volcanic package found in the well is correlated to the Santa Catarina basaltic andesites (70-120 m) that are younger than 0.25 Ma, and probably Holocene. Lacustrine deposits crown the stratigraphic column of the drill core with ages probably younger than 34 ka. The San Lorenzo Tezonco well is in a graben-like structure that was filled with more than 1900 m of volcanic products, suggesting that volcanism were intense in the Miocene to the Recent, and the south drainage of the Mexico Basin was closed probably in the early Pleistocene.

East Asia basin Analysis Project

International Nuclear Information System (INIS)

Terman, M.J.

1986-01-01

The United Nations-related Committee for Coordination of Joint Prospecting for Mineral Resources in Asian Offshore Areas (CCOP), in cooperation with the International Union of Geological Sciences and Circum-Pacific Council, is implementing the East Asia Basin Analysis Project. National and regional organizations, principally members of the ASEAN Council of Petroleum, are compiling maps at a scale of 1:2 million and stratigraphic cross sections of basins, with particular initial emphasis on defining and assessing oil and gas plays and with later analytical focus on other sedimentary minerals (e.g., coal, phosphate, evaporites, and uranium). Completion is anticipated in 1988. Two major elements of the project are being contributed from other agencies. (1) Base maps. - The US Geological Survey (USGS) has partly compiled eight sheets covering east Asia that show bathymetry, shorelines, and drainage systems. One sheet also presents topography and selected cultural features. All sheets are scheduled to be completed in 1987. (2) Geotectonic maps. - The Working Group on Studies of East Asian Tectonics and Resources (SEATAR) is now completing 10 transect studies with crustal profiles and strip maps at a scale of 1:1 million. One map for each transect shows a plate tectonic interpretation. Transect coordinators or others will be encouraged to extrapolate between the strips and complete the geotectonic interpretation (on USGS bases) in 1987. The IGCP Project 220 is also compiling on (USGS bases) the tin and tungsten granites of east Asia, emphasizing geochemical data needed to identify predictive models. Other mapping will probably follow mineral-deposit modeling workshops on ophiolotic chromite and regional symposia on oceanic massive sulfide and subvolcanic gold and base metals. Completion may be possible by 1989

Shear-induced Bubble Coalescence in Rhyolitic Melts with Low Vesicularity

Science.gov (United States)

Okumura, S.; Nakamura, M.; Tsuchiyama, A.

2006-12-01

Development of bubble structure during magma ascent controls the dynamics of volcanic eruption, because the bubble structure influences the magma rheology and permeability, and hence magma degassing. In the flowing magmas, the bubble structure is expected to be changed by shear, as pointed out by some previous studies based on geological observations. However, the development of bubble structure has been experimentally studied only in the isostatic magmas. We have experimentally demonstrated for the first time, the shear-induced development of number density, size and shape of bubbles in a rhyolitic melt. The deformation experiments were performed by using an externally heated, piston-cylinder type apparatus with a rotational piston. At 975°C, natural obsidian (initial water content of 0.5 wt%) having cylindrical shape (ca. 4.7 mm in diameter and 5 mm in length) was vesiculated in the graphite container (ca. 5 and 9 mm in the inner and the outer diameters, respectively, and 5 mm in length), and the vesiculated samples were twisted at various rotational speeds up to 1 rpm. The number density, size and shape of bubbles in the quenched samples were then measured by using the X-ray computed tomography. The size distribution of bubbles shows that the number of larger bubbles increases with the rotational speed and at the outer zone of the samples at which the shear rate is high. In the high shear rate zone, the magnitude of bubble deformation is large. The 3D images of large bubbles clearly indicate that they were formed by coalescence. These results indicate that the degree of bubble coalescence is enhanced with the shear rate. The experimental results also demonstrated that the coalescence of bubbles occur even at low vesicularity (ca. 20 vol.%). Because the shear rate induced in this study (in the order of 0.01 1/s) seems to be produced for magmas ascending in a volcanic conduit, we propose the possibility that the vesiculated magmas undergo bubble coalescence at a

Basin Hopping Graph

DEFF Research Database (Denmark)

Kucharik, Marcel; Hofacker, Ivo; Stadler, Peter

2014-01-01

of the folding free energy landscape, however, can provide the relevant information. Results We introduce the basin hopping graph (BHG) as a novel coarse-grained model of folding landscapes. Each vertex of the BHG is a local minimum, which represents the corresponding basin in the landscape. Its edges connect...

Active intra-basin faulting in the Northern Basin of Lake Malawi from seismic reflection data

Science.gov (United States)

Shillington, D. J.; Chindandali, P. R. N.; Scholz, C. A.; Ebinger, C. J.; Onyango, E. A.; Peterson, K.; Gaherty, J. B.; Nyblade, A.; Accardo, N. J.; McCartney, T.; Oliva, S. J.; Kamihanda, G.; Ferdinand, R.; Salima, J.; Mruma, A. H.

2016-12-01

Many questions remain about the development and evolution of fault systems in weakly extended rifts, including the relative roles of border faults and intra-basin faults, and segmentation at various scales. The northern Lake Malawi (Nyasa) rift in the East African Rift System is an early stage rift exhibiting pronounced tectonic segmentation, which is defined by 100-km-long border faults. The basins also contain a series of intrabasinal faults and associated synrift sediments. The occurrence of the 2009 Karonga Earthquake Sequence on one of these intrabasinal faults indicates that some of them are active. Here we present new multichannel seismic reflection data from the Northern Basin of the Malawi Rift collected in 2015 as a part of the SEGMeNT (Study of Extension and maGmatism in Malawi aNd Tanzania) project. This rift basin is bound on its east side by the west-dipping Livingstone border fault. Over 650 km of seismic reflection profiles were acquired in the Northern Basin using a 500 to 1540 cu in air gun array and a 1200- to 1500-m seismic streamer. Dip lines image a series of north-south oriented west-dipping intra-basin faults and basement reflections up to 5 s twtt near the border fault. Cumulative offsets on intra-basin faults decrease to the west. The largest intra-basin fault has a vertical displacement of >2 s two-way travel time, indicating that it has accommodated significant total extension. Some of these intra-basin faults offset the lake bottom and the youngest sediments by up to 50 s twtt ( 37 m), demonstrating they are still active. The two largest intra-basin faults exhibit the largest offsets of young sediments and also correspond to the area of highest seismicity based on analysis of seismic data from the 89-station SEGMeNT onshore/offshore network (see Peterson et al, this session). Fault patterns in MCS profiles vary along the basin, suggesting a smaller scale of segmentation of faults within the basin; these variations in fault patterns

River basin administration

Science.gov (United States)

Management of international rivers and their basins is the focus of the Centre for Comparative Studies on (International) River Basin Administration, recently established at Delft University of Technology in the Netherlands. Water pollution, sludge, and conflicting interests in the use of water in upstream and downstream parts of a river basin will be addressed by studying groundwater and consumption of water in the whole catchment area of a river.Important aspects of river management are administrative and policy aspects. The Centre will focus on policy, law, planning, and organization, including transboundary cooperation, posing standards, integrated environmental planning on regional scale and environmental impact assessments.

Reconstructing multiple arc-basin systems in the Altai-Junggar area (NW China): Implications for the architecture and evolution of the western Central Asian Orogenic Belt

Science.gov (United States)

Li, Di; He, Dengfa; Tang, Yong

2016-05-01

The Altai-Junggar area in northwestern China is a critical region to gain insights on the tectonic framework and geological evolution of the western Central Asian Orogenic Belt (CAOB). In this study, we report results from integrated geological, geochemical and geophysical investigations on the Wulungu Depression of the Junggar Basin to determine the basement nature of the basin and understand its amalgamation history with the Chinese Altai, within the broad tectonic evolution of the Altai-Junggar area. Based on borehole and seismic data, the Wulungu Depression is subdivided into two NW-trending tectonic units (Suosuoquan Sag and Hongyan High) by southward-vergent thrust faults. The Suosuoquan Sag consists of the Middle-Late Devonian basaltic andesite, andesite, dacite, tuff, tuffaceous sandstone and tuffite, and the overlying Early Carboniferous volcano-sedimentary sequence with lava flows and shallow marine sediments from a proximal juvenile provenance (zircon εHf(t) = 6.0-14.9), compared to the Late Carboniferous andesite and rhyolite in the Hongyan High. Zircon SIMS U-Pb ages for dacites and andesites indicate that these volcanics in the Suosuoquan Sag and Hongyan High erupted at 376.3 Ma and 313.4 Ma, respectively. The Middle-Late Devonian basaltic andesites from well LC1 are calc-alkaline and exhibit primitive magma-like MgO contents (7.9-8.6%) and Mg# values (66-68), with low initial 87Sr/86Sr (0.703269-0.704808) and positive εNd(t) values (6.6-7.6), and relatively high Zr abundance (98.2-116.0 ppm) and Zr/Y ratios (5.1-5.4), enrichment in LREEs and LILEs (e.g., Th and U) and depletion in Nb, Ta and Ti, suggesting that they were probably derived from a metasomatized depleted mantle in a retro-arc extensional setting. The well LC1 andesitic tuffs, well L8 dacites, well WL1 dacitic tuffs and well L5 andesites belong to calc-alkaline and metaluminous to peraluminous (A/CNK = 0.8-1.7) series, and display low Mg# values (35-46) and variably positive εNd(t) (4

Sediment-hosted micro-disseminated gold mineralization constrained by basin paleo-topographic highs in the Youjiang basin, South China

Science.gov (United States)

Liu, Jianming; Ye, Jie; Ying, Hanlong; Liu, Jiajun; Zheng, Minghua; Gu, Xuexiang

2002-06-01

The Youjiang basin is a Devonian-Triassic rift basin on the southern margin of the Yangtze Craton in South China. Strong syndepositional faulting defined the basin-and-range style paleo-topography that further developed into isolated carbonate platforms surrounded by siliciclastic filled depressions. Finally, thick Triassic siliciclastic deposits covered the platforms completely. In the Youjiang basin, numerous sediment-hosted, micro-disseminated gold (SMG) deposits occur mainly in Permian-Triassic chert and siliciclastic rocks. SMG ores are often auriferous sedimentary rocks with relatively low sulfide contents and moderate to weak alteration. Similar to Carlin-type gold ores in North America, SMG ores in the Youjiang basin are characterized by low-temperature mineral assemblages of pyrite, arsenopyrite, realgar, stibnite, cinnabar, marcasite, chalcedony and carbonate. Most of the SMG deposits are remarkably distributed around the carbonate platforms. Accordingly, there are platform-proximal and platform-distal SMG deposits. Platform-proximal SMG deposits often occur in the facies transition zone between the underlying platform carbonate rocks and the overlying siliciclastic rocks with an unconformity (often a paleo-karst surface) in between. In the ores and hostrocks there are abundant synsedimentary-syndiagenetic fabrics such as lamination, convolute bedding, slump texture, soft-sediment deformation etc. indicating submarine hydrothermal deposition and syndepositional faulting. Numerous fluid-escape and liquefaction fabrics imply strong fluid migration during sediment basin evolution. Such large-scale geological and fabric evidence implies that SMG ores were formed during basin evolution, probably in connection with basinal fluids. It is well known that basinal fluids (especially sediment-sourced fluids) will migrate generally (1) upwards, (2) towards basin margins or basin topographic highs, (3) and from thicker towards thinner deposits during basin evolution

Mapping Monthly Water Scarcity in Global Transboundary Basins at Country-Basin Mesh Based Spatial Resolution.

Science.gov (United States)

Degefu, Dagmawi Mulugeta; Weijun, He; Zaiyi, Liao; Liang, Yuan; Zhengwei, Huang; Min, An

2018-02-01

Currently fresh water scarcity is an issue with huge socio-economic and environmental impacts. Transboundary river and lake basins are among the sources of fresh water facing this challenge. Previous studies measured blue water scarcity at different spatial and temporal resolutions. But there is no global water availability and footprint assessment done at country-basin mesh based spatial and monthly temporal resolutions. In this study we assessed water scarcity at these spatial and temporal resolutions. Our results showed that around 1.6 billion people living within the 328 country-basin units out of the 560 we assessed in this study endures severe water scarcity at least for a month within the year. In addition, 175 country-basin units goes through severe water scarcity for 3-12 months in the year. These sub-basins include nearly a billion people. Generally, the results of this study provide insights regarding the number of people and country-basin units experiencing low, moderate, significant and severe water scarcity at a monthly temporal resolution. These insights might help these basins' sharing countries to design and implement sustainable water management and sharing schemes.

New aerogeophysical study of the Eurasia Basin and Lomonosov Ridge: Implications for basin development

DEFF Research Database (Denmark)

Brozena, J.M.; Childers, V.A.; Lawver, L.A.

2003-01-01

In 1998 and 1999, new aerogeophysical surveys of the Arctic Ocean's Eurasia Basin produced the first collocated gravity and magnetic measurements over the western half of the basin. These data increase the density and extend the coverage of the U.S. Navy acromagnetic data from the 1970s. The new...... data reveal prominent bends in the isochrons that provide solid geometrical constraints for plate reconstructions. Tentative identification of anomaly 25 in the Eurasia Basin links early basin opening to spreading in the Labrador Sea before the locus of spreading in the North Atlantic shifted...... to the Norwegian-Greenland Sea. With the opening of the Labrador Sea, Greenland began similar to200 km of northward movement relative to North America and eventually collided with Svalbard, Ellesmere Island, and the nascent Eurasia ocean basin. Both gravity and magnetic data sets reconstructed to times prior...

Great Basin Experimental Range: Annotated bibliography

Science.gov (United States)

E. Durant McArthur; Bryce A. Richardson; Stanley G. Kitchen

2013-01-01

This annotated bibliography documents the research that has been conducted on the Great Basin Experimental Range (GBER, also known as the Utah Experiment Station, Great Basin Station, the Great Basin Branch Experiment Station, Great Basin Experimental Center, and other similar name variants) over the 102 years of its existence. Entries were drawn from the original...

Traces in the dark: sedimentary processes and facies gradients in the upper shale member of the Upper Devonian-Lower Mississippian Bakken Formation, Williston Basin, North Dakota, U.S.A.

Science.gov (United States)

Egenhoff, Sven O.; Fishman, Neil S.

2013-01-01

Black, organic-rich rocks of the upper shale member of the Upper Devonian–Lower Mississippian Bakken Formation, a world-class petroleum source rock in the Williston Basin of the United States and Canada, contain a diverse suite of mudstone lithofacies that were deposited in distinct facies belts. The succession consists of three discrete facies associations (FAs). These comprise: 1) siliceous mudstones; 2) quartz- and carbonate-bearing, laminated mudstones; and 3) macrofossil-debris-bearing massive mudstones. These FAs were deposited in three facies belts that reflect proximal to distal relationships in this mudstone system. The macrofossil-debris-bearing massive mudstones (FA 3) occur in the proximal facies belt and contain erosion surfaces, some with overlying conodont and phosphate–lithoclast lag deposits, mudstones with abundant millimeter-scale siltstone laminae showing irregular lateral thickness changes, and shell debris. In the medial facies belt, quartz- and carbonate-bearing, laminated mudstones dominate, exhibiting sub-millimeter-thick siltstone layers with variable lateral thicknesses and localized mudstone ripples. In the distal siliceous mudstone facies belt, radiolarites, radiolarian-bearing mudstones, and quartz- and carbonate-bearing, laminated mudstones dominate. Overall, total organic carbon (TOC) contents range between about 3 and 10 wt %, with a general proximal to distal decrease in TOC content. Abundant evidence of bioturbation exists in all FAs, and the lithological and TOC variations are paralleled by changes in burrowing style and trace-fossil abundance. While two horizontal traces and two types of fecal strings are recognized in the proximal facies belt, only a single horizontal trace fossil and one type of fecal string characterize mudstones in the distal facies belt. Radiolarites intercalated into the most distal mudstones are devoid of traces and fecal strings. Bedload transport processes, likely caused by storm-induced turbidity

Frequency and sources of basin floor turbidites in alfonso basin, Gulf of California, Mexico: Products of slope failures

Science.gov (United States)

Gonzalez-Yajimovich, Oscar E.; Gorsline, Donn S.; Douglas, Robert G.

2007-07-01

Alfonso Basin is a small margin basin formed by extensional tectonics in the actively rifting, seismically active Gulf of California. The basin is centered at 24°40' N and 110° 38' W, and is a closed depression (maximum depth 420 m) with an effective sill depth of about 320 m (deepest sill), a width of 20 km and length of 25 km. Basin floor area below a depth of 350 m is about 260 km 2. The climate is arid to semiarid but was wetter during the early (ca. 10,000-7000 Calendar years Before Present [BP]) and middle Holocene (ca. 7000-4000 Cal. Years BP). Basin-wide turbidity currents reach the floor of Alfonso Basin at centennial to millennial intervals. The peninsular drainages tributary to the basin are small and have maximum flood discharges of the order of 10 4m 3. The basin-floor turbidites thicker than 1 cm have volumes of the order of 10 6m 3 to 10 8m 3 and require a much larger source. The largest turbidite seen in our cores is ca. 1 m thick in the central basin floor and was deposited 4900 Calendar Years Before Present (BP). Two smaller major events occurred about 1500 and 2800 Cal. Years BP. Seismicity over the past century of record shows a clustering of larger epicenters along faults forming the eastern Gulf side of Alfonso Basin. In that period there have been four earthquakes with magnitudes above 7.0 but all are distant from the basin. Frequency of such earthquakes in the basin vicinity is probably millennial. It is concluded that the basin-wide turbidites thicker than 1 cm must be generated by slope failures on the eastern side of the basin at roughly millennial intervals. The thin flood turbidites have a peninsular source at centennial frequencies.

Paleoclimate cycles and tectonic controls on fluvial, lacustrine, and eolian strata in upper Triassic Chinle Formation, San Juan basin

Energy Technology Data Exchange (ETDEWEB)

Dubiel, R.F. (Geological Survey, Denver, CO (USA))

1989-09-01

Sedimentologic study of the Upper Triassic Chinle Formation in the San Juan basin (SJB) indicates that Late Triassic paleoclimate and tectonic movements influenced the distribution of continental lithofacies. The Shinarump, Monitor Butte, and Petrified Forest Members in the lower part of the Chinle consist of complexly interfingered fluvial, floodplain, marsh, and lacustrine rocks; the Owl Rock and Rock Point Members in the upper part consists of lacustrine-basin and eolian sandsheet strata. Facies analysis, vertebrate and invertebrate paleontology, and paleoclimate models demonstrate that the Late Triassic was dominated by tropical monsoonal circulation, which provided abundant precipitation interspersed with seasonally dry periods. Owl Rock lacustrine strata comprise laminated limestones that reflect seasonal monsoonal precipitation and larger scale, interbedded carbonates and fine-grained clastics that represent longer term, alternating wet and dry climatic cycles. Overlying Rock Point eolian sand-sheet and dune deposits indicate persistent alternating but drier climatic cyclicity. Within the Chinle, upward succession of lacustrine, alternating lacustrine/eolian sand-sheet, and eolian sand-sheet/dune deposits reflects an overall decrease in precipitation due to the northward migration of Pangaea out of low latitudes dominated by monsoonal circulation.

A Non-Member Spouse's Entitlement To The Member's Pension Interest

Directory of Open Access Journals (Sweden)

Motseotsile Clement Marumoagae

2014-12-01

Full Text Available It is important that married couples seek legal advice with regard to the assets falling within their joint estate, more particularly their retirement benefits. This article reflects on the entitlement (if any of non-member spouses to their spouses' retirement fund benefits. Pension benefits can be due before, during or after divorce, and parties to the marriage should be aware of their rights with regard to the accruing pension benefits of their spouses. While it is settled law that non-member spouses are entitled to receive a portion of their member spouses' pension benefits (known as "pension interest" immediately on divorce, it is not particularly clear whether non-member spouses are also entitled to receive the same before or sometime after divorce. In this article I provide a contextual understanding of the entitlements (if any which spouses or former spouses of members of pension funds have on such member spouses' retirement benefits. Furthermore, it shown in this article that various divisions of South African High Courts have been inconsistent in how they have approached the issue of the pension interest between divorcing spouses or divorced ex-spouses.

An Early Permian epithermal gold system in the Tulasu Basin in North Xinjiang, NW China: Constraints from in situ oxygen-sulfur isotopes and geochronology

Science.gov (United States)

Dong, Leilei; Wan, Bo; Deng, Chen; Cai, Keda; Xiao, Wenjiao

2018-03-01

The Axi and Jingxi-Yelmand gold deposits, being the largest gold deposits in the Chinese North Tianshan, NW China, are located ca. l0 km apart in the Tulasu Basin, and are hosted by the Late Devonian - Early Carboniferous Dahalajunshan Formation. In situ LA-ICP-MS titanium analyses on quartz from the Axi and Jingxi-Yelmand deposits are broadly identical. Accordingly, the calculated ore-forming temperatures by Ti-in-quartz thermometer give average temperatures of 279 °C and 294 °C, respectively. Results of in situ SIMS analyses of oxygen and sulfur isotopes on quartz and pyrite from these two deposits are similar. Temperature-corrected fluids of the Axi deposit have δ18O values of 2.6-8.1‰ and δ34S values of 0.8-2.4‰, whereas the fluids of the Jingxi-Yelmand deposit have δ18O of 6.4-8.9‰ and δ34S of -0.4 to 4.0‰. The oxygen and sulfur isotopes from the two deposits indicate a magmatic origin. LA-ICP-MS zircon U-Pb ages of Aqialehe Formation sandstone provided a lower limit for the mineralization timing of the Axi deposit (288 Ma). In situ SIMS U-Pb analyses on entrapped zircon (297 Ma) and newly recognized 284.5 Ma columnar rhyolite implies that the Jingxi-Yelmand deposit formed in the Early Permian. Based on the magmatic affinity of the ore fluids, similar age and ore-formation temperatures, we propose that the Axi and Jingxi-Yelmand deposits comprise an epithermal gold system, which was driven by the same Permian magma in the Tulasu Basin. The ore geological features together with our new results indicate that the Axi and Jingxi-Yelmand deposits are intermediate and high sulfidation type epithermal deposits, respectively.

Multiple ash layers in late Quaternary sediments from the Central Indian Basin

Digital Repository Service at National Institute of Oceanography (India)

Mascarenhas-Pereira, M.B.L.; Nath, B.N.; Iyer, S.D.; Borole, D.V.; Parthiban, G.; Jijin, R.; Khedekar, V.D.

to those originated from Toba, the age (>180 ka) of the shard-bearing sediments was different from the major Quaternary Toba eruptions namely Young, Middle and Old Toba Tuff (YTT, MTT and OTT) and other rhyolitic eruptions in the Indian Ocean. This fact.... 4. Discussion Prior to delving into the discussion it would be pertinent to clarify certain aspects that may have a bearing on the distribution, characteristics, composition, source and age of the volcanic horizons. The premises that we have...

Constraining Basin Depth and Fault Displacement in the Malombe Basin Using Potential Field Methods

Science.gov (United States)

Beresh, S. C. M.; Elifritz, E. A.; Méndez, K.; Johnson, S.; Mynatt, W. G.; Mayle, M.; Atekwana, E. A.; Laó-Dávila, D. A.; Chindandali, P. R. N.; Chisenga, C.; Gondwe, S.; Mkumbwa, M.; Kalaguluka, D.; Kalindekafe, L.; Salima, J.

2017-12-01

The Malombe Basin is part of the Malawi Rift which forms the southern part of the Western Branch of the East African Rift System. At its southern end, the Malawi Rift bifurcates into the Bilila-Mtakataka and Chirobwe-Ntcheu fault systems and the Lake Malombe Rift Basin around the Shire Horst, a competent block under the Nankumba Peninsula. The Malombe Basin is approximately 70km from north to south and 35km at its widest point from east to west, bounded by reversing-polarity border faults. We aim to constrain the depth of the basin to better understand displacement of each border fault. Our work utilizes two east-west gravity profiles across the basin coupled with Source Parameter Imaging (SPI) derived from a high-resolution aeromagnetic survey. The first gravity profile was done across the northern portion of the basin and the second across the southern portion. Gravity and magnetic data will be used to constrain basement depths and the thickness of the sedimentary cover. Additionally, Shuttle Radar Topography Mission (SRTM) data is used to understand the topographic expression of the fault scarps. Estimates for minimum displacement of the border faults on either side of the basin were made by adding the elevation of the scarps to the deepest SPI basement estimates at the basin borders. Our preliminary results using SPI and SRTM data show a minimum displacement of approximately 1.3km for the western border fault; the minimum displacement for the eastern border fault is 740m. However, SPI merely shows the depth to the first significantly magnetic layer in the subsurface, which may or may not be the actual basement layer. Gravimetric readings are based on subsurface density and thus circumvent issues arising from magnetic layers located above the basement; therefore expected results for our work will be to constrain more accurate basin depth by integrating the gravity profiles. Through more accurate basement depth estimates we also gain more accurate displacement

Three-dimensional modeling of pull-apart basins: implications for the tectonics of the Dead Sea Basin

Science.gov (United States)

Katzman, Rafael; ten Brink, Uri S.; Lin, Jian

1995-01-01

We model the three-dimensional (3-D) crustal deformation in a deep pull-apart basin as a result of relative plate motion along a transform system and compare the results to the tectonics of the Dead Sea Basin. The brittle upper crust is modeled by a boundary element technique as an elastic block, broken by two en echelon semi-infinite vertical faults. The deformation is caused by a horizontal displacement that is imposed everywhere at the bottom of the block except in a stress-free “shear zone” in the vicinity of the fault zone. The bottom displacement represents the regional relative plate motion. Results show that the basin deformation depends critically on the width of the shear zone and on the amount of overlap between basin-bounding faults. As the width of the shear zone increases, the depth of the basin decreases, the rotation around a vertical axis near the fault tips decreases, and the basin shape (the distribution of subsidence normalized by the maximum subsidence) becomes broader. In contrast, two-dimensional plane stress modeling predicts a basin shape that is independent of the width of the shear zone. Our models also predict full-graben profiles within the overlapped region between bounding faults and half-graben shapes elsewhere. Increasing overlap also decreases uplift near the fault tips and rotation of blocks within the basin. We suggest that the observed structure of the Dead Sea Basin can be described by a 3-D model having a large overlap (more than 30 km) that probably increased as the basin evolved as a result of a stable shear motion that was distributed laterally over 20 to 40 km.

Geochemical provenance of anomalous metal concentrations in stream sediments in the Ashton 1:250,000 quadrangle, Idaho/Montana/Wyoming

International Nuclear Information System (INIS)

Shannon, S.S. Jr.

1982-01-01

Stream-sediment samples from 1500 sites in the Ashton, Idaho/Montana/Wyoming 1:250,000 quadrangle were analyzed for 45 elements. Almost all samples containing anomalous concentrations (exceeding one standard deviation above the mean value of any element) were derived from drainage basins underlain by Quaternary rhyolite, Tertiary andesite or Precambrian gneiss and schist. Aluminum, barium, calcium, cobalt, iron, nickel, magnesium, scandium, sodium, strontium, and vanadium have no andesite provenance. Most anomalous manganese, europium, hafnium, and zirconium values were derived from Precambrian rocks. All other anomalous elemental concentrations are related to Quaternary rhyolite. This study demonstrates that multielemental stream-sediment analyses can be used to infer the provenance of stream sediments. Such data are available for many parts of the country as a result of the National Uranium Resource Evaluation. This study suggests that stream-sediment samples collected in the Rocky Mountains can be used either as pathfinders or as direct indicators to select targets for mineral exploration for a host of metals

Geology of the central Mineral Mountains, Beaver County, Utah

Energy Technology Data Exchange (ETDEWEB)

Sibbett, B.S.; Nielson, D.L.

1980-03-01

The Mineral Mountains are located in Beaver and Millard Counties, southwestern Utah. The range is a horst located in the transition zone between the Basin and Range and Colorado Plateau geologic provinces. A multiple-phase Tertiary pluton forms most of the range, with Paleozoic rocks exposed on the north and south and Precambrian metamorphic rocks on the west in the Roosevelt Hot Springs KGRA (Known Geothermal Resource Area). Precambrian banded gneiss and Cambrian carbonate rocks have been intruded by foliated granodioritic to monzonitic rocks of uncertain age. The Tertiary pluton consists of six major phases of quartz monzonitic to leucocratic granitic rocks, two diorite stocks, and several more mafic units that form dikes. During uplift of the mountain block, overlying rocks and the upper part of the pluton were partially removed by denudation faulting to the west. The interplay of these low-angle faults and younger northerly trending Basin and Range faults is responsible for the structural control of the Roosevelt Hot Springs geothermal system. The structural complexity of the Roosevelt Hot Springs KGRA is unique within the range, although the same tectonic style continues throughout the range. During the Quaternary, rhyolite volcanism was active in the central part of the range and basaltic volcanism occurred in the northern portion of the map area. The heat source for the geothermal system is probably related to the Quaternary rhyolite volcanic activity.

Quantification and Postglacial evolution of an inner alpine sedimentary basin (Gradenmoos Basin, Hohe Tauern)

International Nuclear Information System (INIS)

Götz, J.

2012-01-01

The overall objective of this thesis is the quantification of sediment storage and the reconstruction of postglacial landscape evolution within the glacially overdeepened Gradenmoos Basin (subcatchment size: 4.1 km 2 ; basin floor elevation: 1920 m) in the central Gradenbach catchment (Schober Range, Hohe Tauern, Austrian Alps). Following the approach of denudation-accumulation-systems, most reliable results are obtained (1) if sediment output of a system can be neglected for an established period of time, (2) if sediment storage can be assessed with a high level of accuracy, (3) if the onset of sedimentation and amounts of initially stored sediments are known, and (4) if sediment contributing areas can be clearly delimited. Due to spatial scale and topographic characteristics, all mentioned aspects are fulfilled to a high degree within the studied basin. Applied methods include surface, subsurface and temporal investigations. Digital elevation data is derived from terrestrial laserscanning and geomorphologic mapping. The quantification of sediment storage is based on core drillings, geophysical methods (DC resistivity, refraction seismic, and ground penetrating radar), as well as GIS and 3D modelling. Radiocarbon dating and palynological analyses are additionally used to reconstruct the postglacial infilling progress of the basin. The study reveals that a continuous postglacial stratigraphic record is archived in the basin. As proposed by Lieb (1987) timing of basin deglaciation could be verified to late-Egesen times by means of radiocarbon ages (oldest sample just above basal till: 10.4 ka cal. BP) and first palynologic results. Lateglacial oscillations seem to have effectively scoured the basin, leaving only a shallow layer of basal till. The analysis of postglacial sedimentation in the basin is further improved by the existence of a former lake in the basin lasting for up to 7500 years until approx. 3.7 ka cal. BP. Both, the stratigraphic (fine, partly

Stratigraphy of the Caloris Basin, Mercury: Implications for Volcanic History and Basin Impact Melt

Science.gov (United States)

Ernst, Carolyn M.; Denevi, Brett W.; Barnouin, Olivier S.; Klimczak, Christian; Chabot, Nancy L.; Head, James W.; Murchie, Scott L.; Neumann, Gregory A.; Prockter, Louis M.; Robinson, Mark S.;

Tectonic setting of Cretaceous basins on the NE Tibetan Plateau: Insights from the Jungong basin

Science.gov (United States)

Craddock, W.H.; Kirby, E.; Dewen, Z.; Jianhui, L.

2012-01-01

Quantifying the Cenozoic growth of high topography in the Indo-Asian collision zone remains challenging, due in part to significant shortening that occurred within Eurasia before collision. A growing body of evidence suggests that regions far removed from the suture zone experienced deformation before and during the early phases of Himalayan orogenesis. In the present-day north-eastern Tibetan Plateau, widespread deposits of Cretaceous sediment attest to significant basin formation; however, the tectonic setting of these basins remains enigmatic. We present a study of a regionally extensive network of sedimentary basins that are spatially associated with a system of SE-vergent thrust faults and are now exposed in the high ranges of the north-eastern corner of the Tibetan Plateau. We focus on a particularly well-exposed basin, located ~20km north of the Kunlun fault in the Anyemaqen Shan. The basin is filled by ~900m of alluvial sediments that become finer-grained away from the basin-bounding fault. Additionally, beds in the proximal footwall of the basin-bounding fault exhibit progressive, up-section shallowing and several intraformational unconformities which can be traced into correlative conformities in the distal part of the basin. The observations show sediment accumulated in the basin during fault motion. Regional constraints on the timing of sediment deposition are provided by both fossil assemblages from the Early Cretaceous, and by K-Ar dating of volcanic rocks that floor and cross-cut sedimentary fill. We argue that during the Cretaceous, the interior NE Tibetan Plateau experienced NW-SE contractional deformation similar to that documented throughout the Qinling-Dabie orogen to the east. The Songpan-Ganzi terrane apparently marked the southern limit of this deformation, such that it may have been a relatively rigid block in the Tibetan lithosphere, separating regions experiencing deformation north of the convergent Tethyan margin from regions deforming

Members of the Agency

International Nuclear Information System (INIS)

2007-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.63) is Palau which deposited its Instrument of Acceptance of the Statute on 2 March 2007. The Attachment hereto shows the dates on which the present 144 Member States became Members [fr

Members of the Agency

International Nuclear Information System (INIS)

2007-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.63) is Palau which deposited its Instrument of Acceptance of the Statute on 2 March 2007. The Attachment hereto shows the dates on which the present 144 Member States became Members [es

Misrepresenting the Jordan River Basin

Directory of Open Access Journals (Sweden)

Clemens Messerschmid

2015-06-01

Full Text Available This article advances a critique of the UN Economic and Social Commission for West Asia’s (ESCWA’s representation of the Jordan River Basin, as contained in its recently published Inventory of Shared Water Resources in Western Asia. We argue that ESCWA’s representation of the Jordan Basin is marked by serious technical errors and a systematic bias in favour of one riparian, Israel, and against the Jordan River’s four Arab riparians. We demonstrate this in relation to ESCWA’s account of the political geography of the Jordan River Basin, which foregrounds Israel and its perspectives and narratives; in relation to hydrology, where Israel’s contribution to the basin is overstated, whilst that of Arab riparians is understated; and in relation to development and abstraction, where Israel’s transformation and use of the basin are underplayed, while Arab impacts are exaggerated. Taken together, this bundle of misrepresentations conveys the impression that it is Israel which is the main contributor to the Jordan River Basin, Arab riparians its chief exploiters. This impression is, we argue, not just false but also surprising, given that the Inventory is in the name of an organisation of Arab states. The evidence discussed here provides a striking illustration of how hegemonic hydro-political narratives are reproduced, including by actors other than basin hegemons themselves.

An integrated approach to investigate the hydrological behavior of the Santa Fe River Basin, north central Florida

Science.gov (United States)

Vibhava, F.; Graham, W. D.; De Rooij, R.; Maxwell, R. M.; Martin, J. B.; Cohen, M. J.

2011-12-01

The Santa Fe River Basin (SFRB) consists of three linked hydrologic units: the upper confined region (UCR), semi-confined transitional region (Cody Escarpment, CE) and lower unconfined region (LUR). Contrasting geological characteristics among these units affect streamflow generation processes. In the UCR, surface runoff and surficial stores dominate whereas in the LCR minimal surface runoff occurs and flow is dominated by groundwater sources and sinks. In the CE region the Santa Fe River (SFR) is captured entirely by a sinkhole into the Floridan aquifer, emerging as a first magnitude spring 6 km to the south. In light of these contrasting hydrological settings, developing a predictive, basin scale, physically-based hydrologic simulation model remains a research challenge. This ongoing study aims to assess the ability of a fully-coupled, physically-based three-dimensional hydrologic model (PARFLOW-CLM), to predict hydrologic conditions in the SFRB. The assessment will include testing the model's ability to adequately represent surface and subsurface flow sources, flow paths, and travel times within the basin as well as the surface-groundwater exchanges throughout the basin. In addition to simulating water fluxes, we also are collecting high resolution specific conductivity data at 10 locations throughout the river. Our objective is to exploit hypothesized strong end-member separation between riverine source water geochemistry to further refine the PARFLOW-CLM representation of riverine mixing and delivery dynamics.

Spatial Preference Heterogeneity for Integrated River Basin Management: The Case of the Shiyang River Basin, China

Directory of Open Access Journals (Sweden)

Fanus Asefaw Aregay

2016-09-01

Full Text Available Integrated river basin management (IRBM programs have been launched in most parts of China to ease escalating environmental degradation. Meanwhile, little is known about the benefits from and the support for these programs. This paper presents a case study of the preference heterogeneity for IRBM in the Shiyang River Basin, China, as measured by the Willingness to Pay (WTP, for a set of major restoration attributes. A discrete choice analysis of relevant restoration attributes was conducted. The results based on a sample of 1012 households in the whole basin show that, on average, there is significant support for integrated ecological restoration as indicated by significant WTP for all ecological attributes. However, residential location induced preference heterogeneities are prevalent. Generally, compared to upper-basin residents, middle sub-basin residents have lower mean WTP while lower sub-basin residents express higher mean WTP. The disparity in utility is partially explained by the difference in ecological and socio-economic status of the residents. In conclusion, estimating welfare benefit of IRBM projects based on sample responses from a specific sub-section of the basin only may either understate or overstate the welfare estimate.

Area environmental characterization report of the Dalhart and Palo Duro basins in the Texas Panhandle. Volume I. Dalhart Basin

International Nuclear Information System (INIS)

1982-09-01

This area report describes the environmental characteristics of the Dalhart and Palo Duro basins of the Texas Panhandle portion of the Permian basin. Both basins are rather sparsely populated, and the overall population is decreasing. The economic base is centered on agribusiness and manufacturing. Most of the potentially conflicting land uses in both basins (i.e., parks, historic sites) occupy small land areas, with the exception of a national grassland in the Dalhart and military air training routes in both basins. Ground transportation in the Dalhart basin is adequate, and it is well developed in the Palo Duro basin. In both basins irrigation constitutes the principal water use, and groundwater is the principal source. However, the dominant aquifer, the Ogallala, is being depleted. Both basins consist primarily of grasslands, rangelands, and agricultural areas. No critical terrestrial or aquatic habitats have been identified in the basins, though several endangered, threatened, or rare terrestrial species occur in or near the basins. Aquatic resources in both basins are limited because of the intermittent availability of water and the high salt content of some water bodies. Playa lakes are common, though usually seasonal or rain dependent. The climate of the area is semiarid, with low humidity, relatively high wind speeds, and highly variable prcipitation. Restrictive dispersion conditions are infrequent. National ambient secondary air quality standards for particulates are being exceeded in the area, largely because of fugitive dust, although there are some particulate point sources

Basin Analysis and Petroleum System Characterisation of Western Bredasdorp Basin, Southern Offshore of South Africa: Insights from a 3d Crust-Scale Basin Model - (Phase 1)

Science.gov (United States)

Sonibare, W. A.; Scheck-Wenderoth, M.; Sippel, J.; Mikeš, D.

2012-04-01

In recent years, construction of 3D geological models and their subsequent upscaling for reservoir simulation has become an important tool within the oil industry for managing hydrocarbon reservoirs and increasing recovery rate. Incorporating petroleum system elements (i.e. source, reservoir and trap) into these models is a relatively new concept that seems very promising to play/prospect risk assessment and reservoir characterisation alike. However, yet to be fully integrated into this multi-disciplinary modelling approach are the qualitative and quantitative impacts of crust-scale basin dynamics on the observed basin-fill architecture and geometries. The focus of this study i.e. Western Bredasdorp Basin constitutes the extreme western section of the larger Bredasdorp sub-basin, which is the westernmost depocentre of the four southern Africa offshore sub-basins (others being Pletmos, Gamtoos and Algoa). These basins, which appear to be initiated by volcanically influenced continental rifting and break-up related to passive margin evolution (during the Mid-Late Jurassic to latest Valanginian), remain previously unstudied for crust-scale basin margin evolution, and particularly in terms of relating deep crustal processes to depo-system reconstruction and petroleum system evolution. Seismic interpretation of 42 2D seismic-reflection profiles forms the basis for maps of 6 stratigraphic horizons which record the syn-rift to post-rift (i.e. early drift and late drift to present-day seafloor) successions. In addition to this established seismic markers, high quality seismic profiles have shown evidence for a pre-rift sequence (i.e. older than Late Jurassic >130 Ma). The first goal of this study is the construction of a 3D gravity-constrained, crust-scale basin model from integration of seismics, well data and cores. This basin model is constructed using GMS (in-house GFZ Geo-Modelling Software) while testing its consistency with the gravity field is performed using IGMAS

The evolution and performance of river basin management in the Murray-Darling Basin

Directory of Open Access Journals (Sweden)

Andrew Ross

2016-09-01

Full Text Available We explore bioregional management in the Murray-Darling Basin (MDB in Australia through the institutional design characteristics of the MDB River Basin Organization (RBO, the actors and organizations who supported and resisted the establishment of the RBO, and the effectiveness of the RBO. During the last 25 years, there has been a major structural reform in the MDB RBO, which has changed from an interstate coordinating body to an Australian government agency. Responsibility for basin management has been centralized under the leadership of the Australian government, and a comprehensive integrated Basin plan has been adopted. The driving forces for this centralization include national policy to restore river basins to sustainable levels of extraction, state government difficulties in reversing overallocation of water entitlements, the millennium drought and its effects, political expediency on the part of the Australian government and state governments, and a major injection of Australian government funding. The increasing hierarchy and centralization of the MDB RBO does not follow a general trend toward multilevel participative governance of RBOs, but decentralization should not be overstated because of the special circumstances at the time of the centralization and the continuing existence of some decentralized elements, such as catchment water plans, land use planning, and water quality. Further swings in the centralization-decentralization pendulum could occur. The MDB reform has succeeded in rebalancing Basin water allocations, including an allocation for the environment and reduced diversion limits. There are some longer term risks to the implementation of reform, including lack of cooperation by state governments, vertical coordination difficulties, and perceived reductions in the accountability and legitimacy of reform at the local level. If implementation of the Basin plan is diverted or delayed, a new institution, the Commonwealth

Sustaining Exploration in Mature Basins

International Nuclear Information System (INIS)

Bayo, A.

2002-01-01

Exploration is a business like any other business driven by opportunity, resources and expectation of profit. Therefore, exploration will thrive anywhere the opportunities are significant, the resources are available and the outlook for profit (or value creation) is good. To sustain exploration activities anywhere, irrespective of the environment, there must be good understanding of the drivers of these key investment criteria. This paper will examine these investment criteria as they relate to exploration business and address the peculiarity of exploration in mature basin. Mature basins are unique environment that lends themselves a mix of fears, paradigms and realities, particularly with respect to the perception of value. To sustain exploration activities in a mature basin, we need to understand these perceptions relative to the true drivers of profitability. Exploration in the mature basins can be as profitable as exploration in emerging basins if the dynamics of value definition-strategic and fiscal values are understood by operators, regulators and co ventures alike. Some suggestions are made in this presentation on what needs to be done in addressing these dynamic investment parameters and sustaining exploration activities in mature basins

L-Reactor 186-basin cleaning alternatives

International Nuclear Information System (INIS)

Turcotte, M.D.S.

1983-01-01

Operation of L Reactor will necessitate annual cleaning of the L Area 186 basins. Alternatives are presented for sediment discharge due to 186-basin cleaning activities as a basis for choosing the optimal cleaning method. Current cleaning activities (i.e. removal of accumulated sediments) for the P, C and K-Area 186 basins result in suspended solids concentrations in the effluent waters above the NPDES limits, requiring an exemption from the NPDES permit for these short-term releases. The objective of mitigating the 186-basin cleaning activities is to decrease the suspended solids concentrations to within permit limits while continuing satisfactory operation of the basins

Crustal characteristic variation in the central Yamato Basin, Japan Sea back-arc basin, deduced from seismic survey results

Science.gov (United States)

Sato, Takeshi; No, Tetsuo; Miura, Seiichi; Kodaira, Shuichi

2018-02-01

The crustal structure of the Yamato Bank, the central Yamato Basin, and the continental shelf in the southern Japan Sea back-arc basin is obtained based on a seismic survey using ocean bottom seismographs and seismic shot to elucidate the back-arc basin formation processes. The central Yamato Basin can be divided into three domains based on the crustal structure: the deep basin, the seamount, and the transition domains. In the deep basin domain, the crust without the sedimentary layer is about 12-13 km thick. Very few units have P-wave velocity of 5.4-6.0 km/s, which corresponds to the continental upper crust. In the seamount and transition domains, the crust without the sedimentary layer is about 12-16 km thick. The P-wave velocities of the upper and lower crusts differs among the deep basin, the seamount, and the transition domains. These results indicate that the central Yamato Basin displays crustal variability in different domains. The crust of the deep basin domain is oceanic in nature and suggests advanced back-arc basin development. The seamount domain might have been affected by volcanic activity after basin opening. In the transition domain, the crust comprises mixed characters of continental and oceanic crust. This crustal variation might represent the influence of different processes in the central Yamato Basin, suggesting that crustal development was influenced not only by back-arc opening processes but also by later volcanic activity. In the Yamato Bank and continental shelf, the upper crust has thickness of about 17-18 km and P-wave velocities of 3.3-4.1 to 6.6 km/s. The Yamato Bank and the continental shelf suggest a continental crustal character.

Palynology, geochemistry and Re-Os age of the Lower-Middle Pennsylvanian stage boundary, central Appalachian basin, USA

Science.gov (United States)

Geboy, N.; Tripathy, G. R.; Ruppert, L. F.; Eble, C. F.; Blake, B. M.; Hannah, J. L.; Stein, H. J.

2014-12-01

The central Appalachian basin (CAB) in the eastern United States contains complicated sedimentary sequences often with thin and discontinuous strata. As an economically important coal-producing region, the basin's architectural framework and depositional history are important to understand. Typically, eustatic marine incursions, marked with black shale deposits, are used for basin-wide correlation. The Betsie Shale Member of the Kanawha Formation represents one of these relatively thick and laterally extensive marine zones. This study examines the palynoflora of the Matewan coalbed, which conformably underlies the Betsie, in the context of a new Re-Os date for the Betsie Shale Member and additional geochemical measures. At its base, the Matewan contains abundant lycopsid tree spores, indicative of a submerged, flooded paleomire. Upsection, biodiversity increases to include small fern and calamite spores as well as cordaite pollen. Combined with an observed increase of inertinite, the diversification of palynoflora suggests surficial peat exposure and drying out of the paleomire. A S-rich (28 wt. %) shaley parting separates these lower and upper benches of the Matewan and may represent an initial marine pulse prior to the glacioeustatic incursion that ultimately flooded the Matewan and deposited the overlying Betsie Shale. The Betsie is organic-rich (3.05 - 4.89 wt. % TOC) with Re and Os content ranging from 320 - 1,200 ppb and 1.5 - 5.3 ppb, respectively. The highly enriched Re values result in notably high parent:daughter ratios (187Re/188Os = 3,644 - 5,737). The Re-Os isotopic data yield a Model 1 age of 323 ± 7.8 Ma (n = 7; MSWD = 0.63) with evidence that the true age lies closer to the younger end of the uncertainty. This age is consistent with previous paleontologic-based interpretations but represents the first directly measured radiometric date for the Betsie. An absolute age for the Betsie is a critical result, as the member is correlated with units in

Detailed north-south cross section showing environments of deposition, organic richness, and thermal maturities of lower Tertiary rocks in the Uinta Basin, Utah

Science.gov (United States)

Johnson, Ronald C.

2014-01-01

The Uinta Basin of northeast Utah has produced large amounts of hydrocarbons from lower Tertiary strata since the 1960s. Recent advances in drilling technologies, in particular the development of efficient methods to drill and hydraulically fracture horizontal wells, has spurred renewed interest in producing hydrocarbons from unconventional low-permeability dolomite and shale reservoirs in the lacustrine, Eocene Green River Formation. The Eocene Green River Formation was deposited in Lake Uinta, a long-lived saline lake that occupied the Uinta Basin, the Piceance Basin to the east, and the intervening Douglas Creek arch. The focus of recent drilling activity has been the informal Uteland Butte member of the Green River Formation and to a much lesser extent the overlying R-0 oil shale zone of the Green River Formation. Initial production rates ranging from 500 to 1,500 barrels of oil equivalent per day have been reported from the Uteland Butte member from horizontal well logs that are as long as 4,000 feet (ft);. The cross section presented here extends northward from outcrop on the southern margin of the basin into the basin’s deep trough, located just south of the Uinta Mountains, and transects the area where this unconventional oil play is developing. The Monument Butte field, which is one of the fields located along this line of section, has produced hydrocarbons from conventional sandstone reservoirs in the lower part of the Green River Formation and underlying Wasatch Formation since 1981. A major fluvial-deltaic system entered Lake Uinta from the south, and this new line of section is ideal for studying the effect of the sediments delivered by this drainage on hydrocarbon reservoirs in the Green River Formation. The cross section also transects the Greater Altamont-Bluebell field in the deepest part of the basin, where hydrocarbons have been produced from fractured, highly overpressured marginal lacustrine and fluvial reservoirs in the Green River, Wasatch

Does formal mentoring for faculty members matter? A survey of clinical faculty members.

Science.gov (United States)

Mylona, Elza; Brubaker, Linda; Williams, Valerie N; Novielli, Karen D; Lyness, Jeffrey M; Pollart, Susan M; Dandar, Valerie; Bunton, Sarah A

2016-06-01

Mentoring relationships, for all medical school faculty members, are an important component of lifelong development and education, yet an understanding of mentoring among medical school clinical faculty members is incomplete. This study examined associations between formal mentoring relationships and aspects of faculty members' engagement and satisfaction. It then explored the variability of these associations across subgroups of clinical faculty members to understand the status of mentoring and outcomes of mentoring relationships. The authors hypothesised that academic clinical faculty members currently in formal mentoring relationships experience enhanced employee engagement and satisfaction with their department and institution. Medical school faculty members at 26 self-selected USA institutions participated in the 2011-2014 Faculty Forward Engagement Survey. Responses from clinical faculty members were analysed for relationships between mentoring status and perceptions of engagement by faculty members. Of the 11 953 clinical faculty respondents, almost one-third reported having a formal mentoring relationship (30%; 3529). Most mentored faculty indicated the relationship was important (86%; n = 3027), and over three-fourths were satisfied with their mentoring experience (77%; n = 2722). Mentored faculty members across ranks reported significantly higher levels of satisfaction and more positive perceptions of their roles in the organisation. Faculty members who were not receiving mentoring reported significantly less satisfaction with their workplace environment and lower overall satisfaction. Mentored clinical faculty members have significantly greater satisfaction with their department and institution. This multi-institutional study provides evidence that fostering mentoring opportunities may facilitate faculty members' satisfaction and engagement, which, in turn, may help medical schools retain high-quality faculty staff committed to the multidimensional

Simulation of water-rock interaction in the yellowstone geothermal system using TOUGHREACT

International Nuclear Information System (INIS)

Dobson, P.F.; Salah, S.; Spycher, N.; Sonnenthal, E.

2003-01-01

The Yellowstone geothermal system provides an ideal opportunity to test the ability of reactive transport models to accurately simulate water-rock interaction. Previous studies of the Yellowstone geothermal system have characterized water-rock interaction through analysis of rocks and fluids obtained from both surface and downhole samples. Fluid chemistry, rock mineralogy, permeability, porosity, and thermal data obtained from the Y-8 borehole in Upper Geyser Basin were used to constrain a series of reactive transport simulations of the Yellowstone geothermal system using TOUGHREACT. Three distinct stratigraphic units were encountered in the 153.4 m deep Y-8 drill core: volcaniclastic sandstone, perlitic rhyolitic lava, and nonwelded pumiceous tuff. The main alteration phases identified in the Y-8 core samples include clay minerals, zeolites, silica polymorphs, adularia, and calcite. Temperatures observed in the Y-8 borehole increase with depth from sub-boiling conditions at the surface to a maximum of 169.8 C at a depth of 104.1 m, with near-isothermal conditions persisting down to the well bottom. 1-D models of the Y-8 core hole were constructed to determine if TOUGHREACT could accurately predict the observed alteration mineral assemblage given the initial rock mineralogy and observed fluid chemistry and temperatures. Preliminary simulations involving the perlitic rhyolitic lava unit are consistent with the observed alteration of rhyolitic glass to form celadonite

Neoproterozoic rift basins and their control on the development of hydrocarbon source rocks in the Tarim Basin, NW China

Science.gov (United States)

Zhu, Guang-You; Ren, Rong; Chen, Fei-Ran; Li, Ting-Ting; Chen, Yong-Quan

2017-12-01

The Proterozoic is demonstrated to be an important period for global petroleum systems. Few exploration breakthroughs, however, have been obtained on the system in the Tarim Basin, NW China. Outcrop, drilling, and seismic data are integrated in this paper to focus on the Neoproterozoic rift basins and related hydrocarbon source rocks in the Tarim Basin. The basin consists of Cryogenian to Ediacaran rifts showing a distribution of N-S differentiation. Compared to the Cryogenian basins, those of the Ediacaran are characterized by deposits in small thickness and wide distribution. Thus, the rifts have a typical dual structure, namely the Cryogenian rifting and Ediacaran depression phases that reveal distinct structural and sedimentary characteristics. The Cryogenian rifting basins are dominated by a series of grabens or half grabens, which have a wedge-shaped rapid filling structure. The basins evolved into Ediacaran depression when the rifting and magmatic activities diminished, and extensive overlapping sedimentation occurred. The distributions of the source rocks are controlled by the Neoproterozoic rifts as follows. The present outcrops lie mostly at the margins of the Cryogenian rifting basins where the rapid deposition dominates and the argillaceous rocks have low total organic carbon (TOC) contents; however, the source rocks with high TOC contents should develop in the center of the basins. The Ediacaran source rocks formed in deep water environment of the stable depressions evolving from the previous rifting basins, and are thus more widespread in the Tarim Basin. The confirmation of the Cryogenian to Ediacaran source rocks would open up a new field for the deep hydrocarbon exploration in the Tarim Basin.

Spent LWR fuel storage costs: reracking, AR basins, and AFR basins

International Nuclear Information System (INIS)

1980-01-01

Whenever possible, fuel storage requirements will be met by reracking existing reactor basins and/or transfer of fuel to available space in other reactor basins. These alternatives represent not only the lowest cost storage options but also the most timely. They are recognized to face environmental and regulatory obstacles. However, such obstacles should be less severe than those that would be encountered with AR or AFR basin storage. When storage requirements cannot be met by the first two options, the least costly alternative for most utilities will be use of a Federal AFR. Storage costs of $100,000 to $150,000 MTU at a AFR are less costly than charges of up to $320,000/MTU that could be incurred by the use of AR basins. AFR storage costs do not include transportation from the reactor to the AFR. This cost would be paid by the utility separately. Only when a utility requires annual storage capacity for 100 MTU of spent fuel can self-storage begin to compete with AFR costs. The large reactor complexes discharging these fuel quantities are not currently those that require relief from fuel storage problems

Geologic Basin Boundaries (Basins_GHGRP) GIS Layer

Data.gov (United States)

U.S. Environmental Protection Agency — This is a coverage shapefile of geologic basin boundaries which are used by EPA's Greenhouse Gas Reporting Program. For onshore production, the "facility" includes...

GEOLOGICAL FEATURES OF NEOGENE BASINS HOSTING BORATE DEPOSITS: AN OVERVIEW OF DEPOSITS AND FUTURE FORECAST, TURKEY

Directory of Open Access Journals (Sweden)

Cahit HELVACI

2015-12-01

hydroboracite are present in west Anatolia, Death Valley, California, and Sijes (Argentina. Quaternary borates are present in salars (Andes and playa- lakes and salt pans (USA-Tibet. Boron is a rare element in the Earth’s crust, but extraordinary concentrations can be found in limited places. The formation of borate deposits can be classified as follows: a skarn group associated with intrusives and consisting of silicates and iron oxides; a magnesium oxide group hosted by marine evaporitic sediments; and a sodium– and calcium–borate hydrates group associated with playa-lake sediments and explosive volcanic activity. Some conditions are essential for the formation of economically viable borate deposits in playa-lake volcano-sedimentary sequences: formation of playa-lake environment; concentration of boron in the playa lake, sourced from andesitic to rhyolitic volcanics, direct ash fall into the basin, or hydrothermal solutions along graben faults; thermal springs near the area of volcanism; arid to semi-arid climatic conditions; and lake water with a pH of between 8.5 and 11. A borate is defined as any compound that contains or supplies boric oxide (B2O3. A large number of minerals contain boric oxide, but the three that are most important from a worldwide commercial standpoint are borax, ulexite, and colemanite, which are produced in a limited number of countries. Turkey has the largest borax, ulexite and colemanite reserves in the world and all the world’s countries are dependent upon the colemanite and ulexite reserves of Turkey. Most of the world’s commercial borate deposits are mined by open pit methods. Brines from Searles Lake, and presumably the Chinese sources, are recovered by either controlled evaporation or carbonation. Boric acid is one of the final products produced from most of the processes. Further research on the mineralogy and chemistry of borate minerals and associated minerals will the production and utilization of borate end-products. �

The Lower Triassic Sorkh Shale Formation of the Tabas Block, east central Iran: Succesion of a failed-rift basin at the Paleotethys margin

Science.gov (United States)

Lasemi, Y.; Ghomashi, M.; Amin-Rasouli, H.; Kheradmand, A.

2008-01-01

The Lower Triassic Sorkh Shale Formation is a dominantly red colored marginal marine succession deposited in the north-south trending Tabas Basin of east central Iran. It is correlated with the unconformity-bounded lower limestone member of the Elika Formation of the Alborz Mountains of northern Iran. The Sorkh Shale is bounded by the pre-Triassic and post-Lower Triassic interregional unconformities and consists mainly of carbonates, sandstones, and evaporites with shale being a minor constituent. Detailed facies analysis of the Sorkh Shale Formation resulted in recognition of several genetically linked peritidal facies that are grouped into restricted subtidal, carbonate tidal flat, siliciclastic tidal flat, coastal plain and continental evaporite facies associations. These were deposited in a low energy, storm-dominated inner-ramp setting with a very gentle slope that fringed the Tabas Block of east central Iran and passed northward (present-day coordinates) into deeper water facies of the Paleotethys passive margin of northern Cimmerian Continent. Numerous carbonate storm beds containing well-rounded intraclasts, ooids and bioclasts of mixed fauna are present in the Sorkh Shale Formation of the northern Tabas Basin. The constituents of the storm beds are absent in the fair weather peritidal facies of the Sorkh Shale Formation, but are present throughout the lower limestone member of the Elika Formation. The Tabas Block, a part of the Cimmerian continent in east central Iran, is a rift basin that developed during Early Ordovician-Silurian Paleotethys rifting. Facies and sequence stratigraphic analyses of the Sorkh Shale Formation has revealed additional evidence supporting the Tabas Block as a failed rift basin related to the Paleotethys passive margin. Absence of constituents of the storm beds in the fair weather peritidal facies of the Sorkh Shale Formation, presence of the constituents of the storm beds in the fair weather facies of the Elika Formation (the

Hydroclimatology of the Missouri River basin

Science.gov (United States)

Wise, Erika K.; Woodhouse, Connie A.; McCabe, Gregory; Pederson, Gregory T.; St. Jacques, Jeannine-Marie

2018-01-01

Despite the importance of the Missouri River for navigation, recreation, habitat, hydroelectric power, and agriculture, relatively little is known about the basic hydroclimatology of the Missouri River basin (MRB). This is of particular concern given the droughts and floods that have occurred over the past several decades and the potential future exacerbation of these extremes by climate change. Here, observed and modeled hydroclimatic data and estimated natural flow records in the MRB are used to 1) assess the major source regions of MRB flow, 2) describe the climatic controls on streamflow in the upper and lower basins , and 3) investigate trends over the instrumental period. Analyses indicate that 72% of MRB runoff is generated by the headwaters in the upper basin and by the lowest portion of the basin near the mouth. Spring precipitation and temperature and winter precipitation impacted by changes in zonal versus meridional flow from the Pacific Ocean play key roles in surface water supply variability in the upper basin. Lower basin flow is significantly correlated with precipitation in late spring and early summer, indicative of Atlantic-influenced circulation variability affecting the flow of moisture from the Gulf of Mexico. Although increases in precipitation in the lower basin are currently overriding the effects of warming temperatures on total MRB flow, the upper basin’s long-term trend toward decreasing flows, reduction in snow versus rain fraction, and warming spring temperatures suggest that the upper basin may less often provide important flow supplements to the lower basin in the future.

An evaluation of public participation in UK river basin management planning

Science.gov (United States)

Schmid, M.; Benson, D.

2012-04-01

The EU Water Framework Directive is reshaping multi-level environmental governance structures in many Member States. One area where re-structuring should be highly visible is in regards to public participation in water management. The Directive legally mandates that implementing agencies should make information publicly available relating to river basin management planning, include the public in the planning process and encourage the active involvement of 'interested parties' both during and after the planning stage. Yet critical questions arise over the extent to which these requirements have actually been met in Member States and the outcomes of participatory processes on the ground. In this study, public participation was evaluated in England and Wales by conducting: a) a broad based quantitative survey of the implementation strategy undertaken across all 11 River Basin Districts (RBDs); and, b) an in-depth analysis of the Anglian RBD drawing on theoretical notions of social learning; a critical measure of participatory processes. Results from the survey showed all RBDs complied with the minimum regulatory requirements on public access to information and written consultation, and even went further with provisions for oral consultation and stakeholder engagement. But the focus was clearly on stakeholder groups with little public involvement beyond minimal legally mandated requirements. Analysis of case study data provided some evidence of social learning at every level (instrumental, communicative and transformative) and beyond the individual scale (wider community and organisational learning). Learning was however significantly limited by participant's high level of expertise and environmental awareness. Also apparent was the influence of other factors, operating at various institutional scales, in shaping learning. The paper then speculates on the implications of the findings for both future research and policy, particularly in light of the European Commission

Rock magnetic characterization of faulted sediments with associated magnetic anomalies in the Albuquerque Basin, Rio Grande rift, New Mexico

Science.gov (United States)

Hudson, M.R.; Grauch, V.J.S.; Minor, S.A.

2008-01-01

Variations in rock magnetic properties are responsible for the many linear, short-wavelength, low-amplitude magnetic anomalies that are spatially associated with faults that cut Neogene basin sediments in the Rio Grande rift, including the San Ysidro normal fault, which is well exposed in the northern part of the Albuquerque Basin. Magnetic-susceptibility measurements from 310 sites distributed through a 1200-m-thick composite section of rift-filling sediments of the Santa Fe Group and prerift Eocene and Cretaceous sedimentary rocks document large variations of magnetic properties juxtaposed by the San Ysidro fault. Mean volume magnetic susceptibilities generally increase upsection through eight map units: from 1.7 to 2.2E-4 in the prerift Eocene and Cretaceous rocks to 9.9E-4-1.2E-3 in three members of the Miocene Zia Formation of the Santa Fe Group to 1.5E-3-3.5E-3 in three members of the Miocene-Pleistocene Arroyo Ojito Formation of the Santa Fe Group. Rock magnetic measurements and petrography indicate that the amount of detrital magnetite and its variable oxidation to maghemite and hematite within the Santa Fe Group sediments are the predominant controls of their magnetic property variations. Magnetic susceptibility increases progressively with sediment grain size within the members of the Arroyo Ojito Formation (deposited in fluvial environments) but within members of the Zia Formation (deposited in mostly eolian environments) reaches highest values in fine to medium sands. Partial oxidation of detrital magnetite is spatially associated with calcite cementation in the Santa Fe Group. Both oxidation and cementation probably reflect past flow of groundwater through permeable zones. Magnetic models for geologic cross sections that incorporate mean magnetic susceptibilities for the different stratigraphic units mimic the aeromagnetic profiles across the San Ysidro fault and demonstrate that the stratigraphic level of dominant magnetic contrast changes with

Wind energy in Mediterranean Basin

International Nuclear Information System (INIS)

Gaudiosi, G.

1991-01-01

In its examination of wind energy potential in the Mediterranean Basin, this paper provides brief notes on the Basin's geography; indicates power production and demand; describes the area's wind characteristics and wind monitoring activities; illustrates wind velocity distributions; estimates local wind power production potential; reviews the Basin's wind energy marketing situation and each bordering country's wind energy programs; surveys installed wind energy farms; and assesses national research and commercialization efforts

The Red Sea and Gulf of Aden Basins

Science.gov (United States)

Bosworth, William; Huchon, Philippe; McClay, Ken

2005-10-01

We here summarize the evolution of the greater Red Sea-Gulf of Aden rift system, which includes the Gulfs of Suez and Aqaba, the Red Sea and Gulf of Aden marine basins and their continental margins, and the Afar region. Plume related basaltic trap volcanism began in Ethiopia, NE Sudan (Derudeb), and SW Yemen at ˜31 Ma, followed by rhyolitic volcanism at ˜30 Ma. Volcanism thereafter spread northward to Harrats Sirat, Hadan, Ishara-Khirsat, and Ar Rahat in western Saudi Arabia. This early magmatism occurred without significant extension, and continued to ˜25 Ma. Much of the Red Sea and Gulf of Aden region was at or near sea level at this time. Starting between ˜29.9 and 28.7 Ma, marine syn-tectonic sediments were deposited on continental crust in the central Gulf of Aden. At the same time the Horn of Africa became emergent. By ˜27.5-23.8 Ma a small rift basin was forming in the Eritrean Red Sea. At approximately the same time (˜25 Ma), extension and rifting commenced within Afar itself. At ˜24 Ma, a new phase of volcanism, principally basaltic dikes but also layered gabbro and granophyre bodies, appeared nearly synchronously throughout the entire Red Sea, from Afar and Yemen to northern Egypt. This second phase of magmatism was accompanied in the Red Sea by strong rift-normal extension and deposition of syn-tectonic sediments, mostly of marine and marginal marine affinity. Sedimentary facies were laterally heterogeneous, being comprised of inter-fingering siliciclastics, evaporite, and carbonate. Throughout the Red Sea, the principal phase of rift shoulder uplift and rapid syn-rift subsidence followed shortly thereafter at ˜20 Ma. Water depths increased dramatically and sedimentation changed to predominantly Globigerina-rich marl and deepwater limestone. Within a few million years of its initiation in the mid-Oligocene the Gulf of Aden continental rift linked the Owen fracture zone (oceanic crust) with the Afar plume. The principal driving force for extension

Landscape scale heterogeneity in the East Turkana ecosystem during the Okote Member (1.56-1.38 Ma).

Science.gov (United States)

Patterson, D B; Braun, D R; Behrensmeyer, A K; Lehmann, S B; Merritt, S R; Reeves, J S; Wood, B A; Bobe, R

2017-11-01

Placing the biological adaptations of Pleistocene hominins within a well-resolved ecological framework has been a longstanding goal of paleoanthropology. This effort, however, has been challenging due to the discontinuous nature of paleoecological data spanning many important periods in hominin evolution. Sediments from the Upper Burgi (1.98-1.87 Ma), KBS (1.87-1.56 Ma) and Okote (1.56-1.38 Ma) members of the Koobi Fora Formation at East Turkana in northern Kenya document an important time interval in the evolutionary history of the hominin genera Homo and Paranthropus. Although much attention has been paid to Upper Burgi and KBS member deposits, far less is known regarding the East Turkana paleoecosystem during Okote Member times. This study pairs spatially-resolved faunal abundance data with stable isotope geochemistry from mammalian enamel to investigate landscape-scale ecosystem variability during Okote Member times. We find that during this period 1) taxa within the East Turkana large mammal community were distributed heterogeneously across space, 2) the abundance of C 3 and C 4 vegetation varied between East Turkana subregions, and 3) the Karari subregion, an area with abundant evidence of hominin stone tool manufacture, had significantly more C 3 vegetation than regions closer to the central axis of the Turkana Basin (i.e., Ileret and Koobi Fora). These findings indicate that the East Turkana paleoecosystem during the Okote Member was highly variable across space and provided a complex adaptive landscape for Pleistocene hominins. Copyright © 2017 Elsevier Ltd. All rights reserved.

STRATIGRAPHIC EVOLUTION, PALEOENVIRONMENTS AND HYDROCARBON POTENTIALS OF THE BENUE/DAHOMEY BASINS, NIGERIAN AND POTIGUAR/CEARA BASINS, NE BRAZIL

International Nuclear Information System (INIS)

Akande, S.O; Adekeye, O.A.; Oj, O.J; Erdtmann, B.D.; Koutsokous, E.I.

2004-01-01

The stratigraphy, facies relationship and paleoenvironment of selected West African and the Brazillian rift basins permit the recognition of at least two major petroleum systems apart from the prolific Niger Delta petroleum system. The Lower Cretaceous fluivio-lacustrine petroleum system and Upper Cretaceous to Lower Tertiary, marine dominated petroleum system. Our combined studies of the stratigraphic, structural framework, paleoenvironment and time-space relationships of the petroleum systems in the Benue/Dahomey and the Potiguar/Ceara basins indicated that rifting and subsequent drifting during the opening of the South Atlantic controlled subsidence, sediment deposition and facies associations in individual basins. Whereas in the Potiguar/Ceara basins, the best developed source rocks are within the Neomacin-Aptian fluvio- lacustrine sequence of the Pendencia and Alagamar Formations which generated reserved hydrocarbon in the Acu Formation, empirical evidence for this petroleum system in the contiguous Benue/Dahomey basins are only based on the geochemical characteristics of the lower parts of the Bima Formation and the Abeokuta Group. In contrast, the Upper Cretaceous-Lower Tertiary marine petroleum system, which is constrained by poor development of reservoirs in the Potiguar/Ceara basin is productive in the Benue/Dahomey basins where source rocks, reservoir and sealing facies occur at this interval. Considering the recent hydrocarbon discoveries of the East Niger basin, the Doba (southern Chad), the Muglad basin (southern Sudan) sourced from the fluvio-lacustrine rift sequences, we suggest that this petroleum system needs more detailed exploration and has some potentials in the Benue/Dahomey frontier basins

Area environmental characterization report of the Dalhart and Palo Duro basins in the Texas Panhandle. Volume II. Palo Duro basin

International Nuclear Information System (INIS)

1982-09-01

This area report describes the environmental characteristics of the Dalhart and Palo Duro basins of the Texas Panhandle portion of the Permian basin. Both basins are rather sparsely populated, and the overall population is decreasing. The economic base is centered on agribusiness and manufacturing. Most of the potentially conflicting land uses in both basins (i.e., parks, historic sites) occupy small land areas, with the exception of a national grassland in the Dalhart and military air training routes in both basins. Ground transportation in the Dalhart basin is adequate, and it is well developed in the Palo Duro basin. In both basins irrigation constitutes the principal water use, and groundwater is the principal source. However, the dominant aquifer, the Ogallala, is being depleted. Both basins consist primarily of grasslands, rangelands, and agricultural areas. No critical terrestrial or aquatic habitats have been identified in the basins, though several endangered, threatened, or rare terrestrial species occur in or near the basins. Aquatic resources in both basins are limited because of the intermittent availability of water and the high salt content of some water bodies. Playa lakes are common, though usually seasonal or rain dependent. The climate of the area is semiarid, with low humidity, relatively high wind speeds, and high variable precipitation. Restrictive dispersion conditions are infrequent. National ambient secondary air quality standards for particulates are being exceeded in the area, largely because of fugitive dust, although there are some particulate point sources

Graben calderas of the Sierra Madre Occidental: The case of Guanajuato, central Mexico

Science.gov (United States)

Aguirre-Diaz, G. J.; Tristán-González, M.; Labarthe-Hernández, G.; Marti, J.

2013-12-01

deposits occur along this orthogonal faulting network, but mainly along the NW fault of Veta Madre that crosses through the center of the caldera. The mid-Tertiary stratigraphy in Guanajuato follows the general sequence observed in graben calderas; i.e., from oldest to youngest includes 1) at least 1,500 m of alluvial fan deposits within a tectonic basin (Guanajuato Red Conglomerate), 2) pyroclastic flow deposits, consisting of surge deposits (Loseros Formation) that are concordant with a massive, large volume, rhyolitic ignimbrite (Bufa Rhyolite), which is covered by a layered series of pyroclastic flow deposits (Calderones Formation), and 3) effusive volcanism in the form of rhyolitic lava domes (Chichíndaro Rhyolite) and basaltic-andesite dikes and lavas (Cedros Andesite). The Guanajuato graben caldera formed at about 33 Ma, based on our new U-Pb zr age of the main ignimbrite, Bufa Rhyolite.

2D Seismic Velocity Modelling in the Southeastern Romanian Carpathians and its Foreland (Vrancea Zone and Focsani Basin)

Science.gov (United States)

Stephenson, R.; Bocin, A.; Tryggvason, A.

2003-12-01

The DACIA-PLAN (Danube and Carpathian Integrated Action on Processes in the Lithosphere and Neotectonics) deep seismic reflection survey was performed in August-September 2001, with the objective of obtaining of new information on the deep structure of the external Carpathians nappes and the architecture of Tertiary/Quaternary basins developed within and adjacent to the seismically-active Vrancea Zone, including the rapidly subsiding Focsani Basin. The DACIA-PLAN profile is about 140 km long, having a roughly NW-SE direction, from near the southeast Transylvanian Basin, across the mountainous southeastern Carpathians and their foreland to near the Danube Dalta. A high resolution 2D velocity model of the upper crust along the seismic profile has been determined from a first-arrival tomographic inversion of the DACIA-PLAN data. The shallowing of Palaeozoic-Mesozoic basement, and related structural heterogeneity within it, beneath the eastern flank of the Focsani Basin is clearly seen. Velocity heterogeneity within the Carpathian nappe belt is also evident and is indicative of internal structural complexity, including the presence of salt bodies and basement involvement in thrusting, thus favouring some current geological models over others. The presence of basement involvement implies the compressional reactivation of pre-existing basement normal faults. Members of the DACIA-PLAN/TomoSeis Working Group (see poster) should be considered as co-authors of this presentation.

Geological exploration of uranium ores at Burgos' basin

International Nuclear Information System (INIS)

Cabrera Valdez, M.E.

1975-01-01

The outcrop sediments of the Burgos river basin cover the complete Cenozoic sequence from the Pallaeocene to recent date, and are arranged in the form of parallel strips with a regional dip towards the east, in which direction the sediments become steadily younger. Generally speaking they correspond to a regressive process the lithology of which is an alternation of shales, sandstones, tuffaceous material and conglomerates. The explorations and evaluations of sedimentary uranium deposits so far carried out in the north-east of Mexico show close relationships between the mineralization and the sedimentary processes of the enclosing rock. Analysis of the sedimentary-type uranium ore bodies in Mexico indicates characteristics very similar to those found in the deposits of the same type which were first studied and described in southern Texas and were used as a standard for the first exploratory studies. The uranium ore in the State of Texas is found in sands belonging mainly to the Jackson group of the Eocene and, to a lesser extent, the Catahoula formation of Miocene-Oligocene age. In the Burgos basin the existence of uranium deposits in the non-marine Frio formation of Oligocene age, with geological characteristics similar to the Texan deposits, has been demonstrated. This comparative analysis suggests very good prospects for uranium exploration in the region; it is recommended that priority be given to intensive study of the sediments of the non-marine member of the Frio formation, and the Jackson and Catahoula formations. (author)

The Minorca Basin: a buffer zone between the Valencia and Liguro-Provençal Basins (NW Mediterranean Sea)

Science.gov (United States)

Pellen, Romain; Aslanian, Daniel; Rabineau, Marina; Leroux, Estelle; Gorini, Christian; Silenziario, Carmine; Blanpied, Christian; Rubino, Jean-Loup

2017-04-01

The present-day compartmented Mediterranean physiography is inherited from the last 250 Ma kinematic plate evolution (Eurasian, Africa, Iberic and Nubia plates) which implied the formation of orogenic chains, polyphased basins, and morphological - geodynamic thresholds. The interactions between these entities are strongly debated in the North-Western Mediterranean area. Several Neogene reconstructions have been proposed for the Valencia basin depending of the basin segmentation where each model imply a different subsidence, sedimentary, and palaeo-environmental evolution. Our study propose a new kinematic model for the Valencia Basin (VB) that encompasses the sedimentary infill, vertical movement and basin segmentation. Detailed analyses of seismic profiles and boreholes in the VB reveal a differentiated basin, the Minorca Basin (MB), lying between the old Mesozoic Valencia Basin sensu strico (VBss) and the young Oligocene Liguro-Provencal Basin (LPB) (Pellen et al., 2016). The relationship between these basins is shown through the correlation of four Miocene-to-present-day megasequences. The Central and North Balearic Fracture Zones (CFZ and NBFZ) that border the MB represent two morphological and geodynamical thresholds that created an accommodation in steps between the three domains. Little to no horizontal Neogene movements have been found for the Ibiza and Majorca Islands and imply a vertical "sag" subsidence. In contrast, the counterclockwise movement of the Corso-Sardinian blocks induced a counterclockwise movement of the Minorca block towards the SE along the CFZ and NBFZ, during the exhumation of lower continental crust in the LPB. The South-Eastward Minorca block translation stops when the first atypical oceanic crust occurs. The influence of the Neogene Betic compressional phase is thus limited to the VBss on the basis of a different MB origin. This new understanding places the AlKaPeCa blocks northeastward of the present-day Alboran Area. Both NW-SE and

Geology and geochronology of the Tana Basin, Ethiopia: LIP volcanism, super eruptions and Eocene-Oligocene environmental change

Science.gov (United States)

Prave, A. R.; Bates, C. R.; Donaldson, C. H.; Toland, H.; Condon, D. J.; Mark, D.; Raub, T. D.

2016-06-01

New geological and geochronological data define four episodes of volcanism for the Lake Tana region in the northern Ethiopian portion of the Afro-Arabian Large Igneous Province (LIP): pre-31 Ma flood basalt that yielded a single 40Ar/39Ar age of 34.05 ± 0.54 / 0.56 Ma; thick and extensive felsic ignimbrites and rhyolites (minimum volume of 2- 3 ×103 km3) erupted between 31.108 ± 0.020 / 0.041 Ma and 30.844 ± 0.027 / 0.046 Ma (U-Pb CA-ID-TIMS zircon ages); mafic volcanism bracketed by 40Ar/39Ar ages of 28.90 ± 0.12 / 0.14 Ma and 23.75 ± 0.02 / 0.04 Ma; and localised scoraceous basalt with an 40Ar/39Ar age of 0.033 ± 0.005 / 0.005 Ma. The felsic volcanism was the product of super eruptions that created a 60-80 km diameter caldera marked by km-scale caldera-collapse fault blocks and a steep-sided basin filled with a minimum of 180 m of sediment and the present-day Lake Tana. These new data enable mapping, with a finer resolution than previously possible, Afro-Arabian LIP volcanism onto the timeline of the Eocene-Oligocene transition and show that neither the mafic nor silicic volcanism coincides directly with perturbations in the geochemical records that span that transition. Our results reinforce the view that it is not the development of a LIP alone but its rate of effusion that contributes to inducing global-scale environmental change.

U-Pb and Lu-Hf zircon geochronology of the Cañadón Asfalto Basin, Chubut, Argentina: Implications for the magmatic evolution in central Patagonia

Science.gov (United States)

Hauser, N.; Cabaleri, N. G.; Gallego, O. F.; Monferran, M. D.; Silva Nieto, D.; Armella, C.; Matteini, M.; Aparicio González, P. A.; Pimentel, M. M.; Volkheimer, W.; Reimold, W. U.

2017-10-01

The Cañadón Asfalto basin, central Chubut, Argentina, comprises a volcano-sedimentary sequence related to the opening of the Atlantic Ocean during Mesozoic times. The Lonco Trapial, Cañadón Asfalto and Cañadón Calcáreo formations are the main units related to the evolution of this basin. The Las Chacritas and Puesto Almada members are distinguished in the Cañadón Asfalto Formation. LA-HR-ICP-MS U-Pb and Lu-Hf data on zircon were obtained on these units. The Lonco Trapial Formation gave a weighted average age of 172.3 ± 1.8 Ma. A pyroclastic level from the Las Chacritas Member gave a weighted average age of 168.2 ± 2.2 Ma. Two U-Pb concordant ages of 160.3 ± 1.7 Ma on a laminated tuffite and 158.3 ± 1.3 Ma on a pyroclastic level were obtained for the Puesto Almada Member. Two maximum depositional ages constrain the sedimentary provenance areas for the basin: 1) A sample from the Sierra de la Manea range, where a controversial unit related either to the Cañadón Asfalto or to the Cañadón Calcáreo formation occurs, gave an age of 176.6 ± 1.0 Ma. Two younger zircon crystals indicate that this unit may be related to the Cañadón Calcáreo Formation. 2) A sandstone with cross-stratification from the Puesto Almada Member gave a maximum depositional age of 173.6 ± 6.4 Ma. In terms of U-Pb and Lu-Hf isotopes, two magmatic events are identified in central Patagonia: the Mamil Choique magmatic event characterized by negative εHf values around -5.0 and representing recycling during Permian times of Mesoproterozoic crust (TDM of ∼1.5 Ga), and the Cañadón Asfalto magmatic event with negative (-8.2) to positive (+4) εHf values and Meso- to Neoproterozoic TDM between 1.5 and 0.8 Ga. The younger event is characterized by three main cycles: C1 related to the Lonco Trapial magmatism, C2 to the Las Chacritas volcanism, and C3 to the Puesto Almada volcanism. These cycles are related with Marifil, Chon Aike and El Quemado formations volcanics events of

Hydration of Rhyolitic Glasses: Comparison Between High- and Low-Temperature Processes

Science.gov (United States)

Anovitz, L.; Fayek, M.; Cole, D. R.; Carter, T.

2012-12-01

While a great deal is known about the interaction between water and rhyolitic glasses and melts at temperatures above the glass transition, the nature of this interaction at lower temperatures is more obscure. Comparisons between high- and low-temperature diffusive studies suggest that several factors play an important role under lower-temperatures conditions that are not significant at higher temperatures. Surface concentrations, which equilibrate quickly at high temperature, change far more slowly as temperatures decrease, and may not equilibrate at room temperature for hundreds or thousands of years. Coupled with temperature-dependent diffusion coefficients this complicates calculation of diffusion profiles as a function of time. A key factor in this process appears to be the inability of "self-stress", caused by the in-diffusing species, to relax at lower temperatures, a result expected below the glass transition. Regions of the glass hydrated at low temperatures are strongly optically anisotropic, and preliminary calculations suggest that the magnitude of stress involved may be very high. On the microstuctural scale, extrapolations of high-temperature FTIR data to lower temperatures suggests there should be little or no hydroxyl present in glasses "hydrated" at low temperatures. Analyses of both block and powder samples suggest that this is generally true in the bulk of the hydrated glass, excluding hydroxyl groups that formed during the initial cooling of the melt. However, hydroxyl do groups appear to be present at the glass surface, where both SIMS and neutron reflectometry data suggest hydration levels may be higher than projected from the bulk of the glass. Isotopic exchange experiments also suggest that bonding is relatively weak, as hydration water exchanges readily with the enviroment. All of these observations lead to the conclusion that the observed stress is due to the presence of interstructural, rather than bonded, water. This likely explains the

Hydrologic Sub-basins of Greenland

Data.gov (United States)

National Aeronautics and Space Administration — The Hydrologic Sub-basins of Greenland data set contains Geographic Information System (GIS) polygon shapefiles that include 293 hydrologic sub-basins of the...

Petroleum geology of the Palo Duro Basin, Texas Panhandle

International Nuclear Information System (INIS)

Rose, P.R.

1986-03-01

The Palo Duro Basin, Permian Basin, Texas is an asymmetric, relatively shallow, intracratonic basin in the southern Texas Panhandle filled mostly by Mississippian, Pennsylvanian, and Permian sedimentary rocks. Although deeper and prolific prolific petroleum-producing basins adjoin it on the north (Anadarko Basin), south (Midland Basin), and east (Hardeman Basin), the Palo Duro Basin has produced remarkably small amounts of oil and gas to date. This is all the more noteworthy because the sedimentary sequence and rock types of the basin are similar to those of the adjacent basins. Analyses of the stratigraphic succession and structural configuration of the Palo Duro Basin suggest that adequate reservoir rocks, top-seals, and geologic structures are present. Most of the structures formed early enough to have trapped hydrocarbons if they were migrating in the rock column. Although additional work is under way to properly address the question of the petroleum source rocks, generation, and migration, the general absence of production in the basin may relate to an overall deficiency in hydrocarbon generation within the basin. Geologic information in this report will form part of the basis for further analysis and conclusions on hydrocarbon potential in the Palo Duro Basin

Evolution of the Rembrandt impact basin on Mercury.

Science.gov (United States)

Watters, Thomas R; Head, James W; Solomon, Sean C; Robinson, Mark S; Chapman, Clark R; Denevi, Brett W; Fassett, Caleb I; Murchie, Scott L; Strom, Robert G

2009-05-01

MESSENGER's second Mercury flyby revealed a ~715-kilometer-diameter impact basin, the second-largest well-preserved basin-scale impact structure known on the planet. The Rembrandt basin is comparable in age to the Caloris basin, is partially flooded by volcanic plains, and displays a unique wheel-and-spoke-like pattern of basin-radial and basin-concentric wrinkle ridges and graben. Stratigraphic relations indicate a multistaged infilling and deformational history involving successive or overlapping phases of contractional and extensional deformation. The youngest deformation of the basin involved the formation of a approximately 1000-kilometer-long lobate scarp, a product of the global cooling and contraction of Mercury.

Miocene block uplift and basin formation in the Patagonian foreland: The Gastre Basin, Argentina

Science.gov (United States)

Bilmes, A.; D'Elia, L.; Franzese, J. R.; Veiga, G. D.; Hernández, M.

2013-08-01

The intraplate fault-block mountains and intermontane deposits of the Gastre Basin, which are recorded more than 550 km east of the Andean trench in central Patagonia, Argentina, are analyzed. The Gastre Basin is one of the largest Patagonian intermontane basins, limited by uplifted blocks strongly oblique to the Andean chain. It was originated by reverse faulting and inversion of pre-existing normal faults associated with a Mesozoic rift basin and defined by older crustal heterogeneities. The deformational event occurred during the middle Miocene, related to a short contractional episode (16.1-14.86 Ma), probably in response to an eastward migration of the Andean fold and thrust belt. During Pliocene to Quaternary times, neither younger fault-block uplifts nor reconfigurations of the basin occurred. Similarities between the study area and other parts of the Patagonian foreland - such as the presence of Miocene reverse or inversion tectonics, as well as the accommodation of the Miocene sedimentary successions - suggest that the Gastre Basin is part of a major late early to middle Miocene broken foreland system (i.e. the Patagonian broken foreland) that exhumed discrete fault-block mountains and generated contemporary basins along more than 950 km parallel to the Andean trench (i.e. between 40°00' and 48°00' south latitude). Based on recent studies on the southern Andean Margin, this continental-scale contractional episode may be the result of a flat-slab subduction segment. Nevertheless, such a hypothesis is very difficult to support when analyzing such a large flat subduction segment along the entire Patagonian trench. This suggests the need to consider alternative flat-slab trigger mechanisms or other factors in the generation of broken foreland systems.

5. Basin assessment and watershed analysis

Science.gov (United States)

Leslie M. Reid; Robert R. Ziemer

1994-01-01

Abstract - Basin assessment is an important component of the President's Forest Plan, yet it has received little attention. Basin assessments are intended both to guide watershed analyses by specifying types of issues and interactions that need to be understood, and, eventually, to integrate the results of watershed analyses occurring within a river basin....

A Basin Approach to a Hydrological Service Delivery System in the Amur River Basin

Directory of Open Access Journals (Sweden)

Sergei Borsch

2018-03-01

Full Text Available This paper presents the basin approach to the design, development, and operation of a hydrological forecasting and early warning system in a large transboundary river basin of high flood potential, where accurate, reliable, and timely available daily water-level and reservoir-inflow forecasts are essential for water-related economic and social activities (the Amur River basin case study. Key aspects of basin-scale system planning and implementation are considered, from choosing efficient forecast models and techniques, to developing and operating data-management procedures, to disseminating operational forecasts using web-GIS. The latter, making the relevant forecast data available in real time (via Internet, visual, and well interpretable, serves as a good tool for raising awareness of possible floods in a large region with transport and industrial hubs located alongside the Amur River (Khabarovsk, Komsomolsk-on-Amur.

Analysis of efficiency of pollution reduction measures in rural basin using MIKE Basin model. Case study: Olšava River Basin

Directory of Open Access Journals (Sweden)

Kaiglová Jana

2014-03-01

Full Text Available This paper presents the results of testing the applicability of the MIKE Basin model for simulating the efficiency of scenarios for reducing water pollution. The model has been tested on the Olšava River Basin (520 km2 which is a typical rural region with a heterogeneous mix of pollution sources with variable topography and land use. The study proved that the model can be calibrated successfully using even the limited amount of data typically available in rural basins. The scenarios of pollution reduction were based on implementation and intensification of municipal wastewater treatment and conversion of arable land on fields under the risk of soil erosion to permanent grassland. The application of simulation results of these scenarios with proposed measures proved decreasing concentrations in downstream monitoring stations. Due to the practical applicability of proposed measures, these could lead to fulfilment of the water pollution limits required by the Czech and EU legislation. However, there are factors of uncertainty that are discussed that may delay or limit the effect of adopted measures in small rural basins.

Astronomically Forced Hydrology of the Late Cretaceous Sub-tropical Potosí Basin, Bolivia

Science.gov (United States)

Tasistro-Hart, A.; Maloof, A. C.; Schoene, B.; Eddy, M. P.

2017-12-01

Orbital forcings paced the ice ages of the Pleistocene, demonstrating that periodic variations in the latitudinal distribution of insolation amplified by ice-albedo feedbacks can guide global climate. How these forcings operate in the hot-houses that span most of the planet's history, however, is unknown. The lacustrine El Molino formation of the late Cretaceous-early Paleogene Potosí Basin in present-day Bolivia contains carbonate-mud parasequences that record fluctuating hydrological conditions from 73 to 63 Ma. This study presents the first cyclostratigraphic analysis using high-resolution drone-derived imagery and 3D elevation models, combined with conventional stratigraphic measurements and magnetic susceptibility data. The drone-derived data are integrated over the entire outcrop at two field areas using a novel application of stratigraphic potential field modeling that increases signal-to-noise ratios prior to spectral analysis. We demonstrate that these parasequences exhibit significant periodicities consistent with eccentricity (400 and 100 kyr), obliquity (50 kyr, 40 kyr, and 29 kyr), precession (17-23 kyr), and semi-precession (9-11 kyr). New U-Pb ID-TIMS zircon ages from intercalacted ash beds corroborate the interpreted sedimentation rates at two sites, indicating that the Potosí Basin contains evidence for hot-house astronomical forcing of sub-tropical lacustrine hydrology. Global climate simulations of late Cretaceous orbital end-member configurations demonstrate precessional-eccentricity and obliquity driven modulation of basin hydrology. In model simulations, the forcings drive long-term shifts in the location of the intertropical convergence zone, changing precipitation along the northern extent of the Potosí Basin's catchment area. This study is the first to demonstrate orbital forcing of a lacustrine system during the Maastrichtian and could ultimately contribute to a precise age for the Cretaceous-Paleogene boundary.

California Basin Studies (CaBS)

International Nuclear Information System (INIS)

Gorsline, D.S.

1991-01-01

The California Continental Borderland's present configuration dates from about 4 to 5 X 10 6 years Before Present (B.P.) and is the most recent of several configurations of the southern California margin that have evolved after the North America Plate over-rode the East Pacific Rise about 30 X 10 6 years ago. The present morphology is a series of two to three northwest-southeast trending rows of depressions separated by banks and insular ridges. Two inner basins, Santa Monica and San Pedro, have been the site for the Department of Energy-funded California Basin Study (CaBS) Santa Monica and San Pedro Basins contain post-Miocene sediment thicknesses of about 2.5 and 1.5 km respectively. During the Holocene (past 10,000 years) about 10-12 m have accumulated. The sediment entered the basin by one or a combination of processes including particle infall (mainly as bioaggregates) from surface waters, from nepheloid plumes (surface, mid-depths and near-bottom), from turbidity currents, mass movements, and to a very minor degree direct precipitation. In Santa Monica Basin, during the last century, particle infall and nepheloid plume transport have been the most common processes. The former dominates in the central basin floor in water depths from 900 to 945 m. where a characteristic silt-clay with a typical mean diameter of about 0.006 mm, phi standard deviation

Basalt stratigraphy - Pasco Basin

International Nuclear Information System (INIS)

Waters, A.C.; Myers, C.W.; Brown, D.J.; Ledgerwood, R.K.

1979-10-01

The geologic history of the Pasco Basin is sketched. Study of the stratigraphy of the area involved a number of techniques including major-element chemistry, paleomagnetic investigations, borehole logging, and other geophysical survey methods. Grande Ronde basalt accumulation in the Pasco Basin is described. An illustrative log response is shown. 1 figure

Bottom water circulation in Cascadia Basin

Science.gov (United States)

Hautala, Susan L.; Paul Johnson, H.; Hammond, Douglas E.

2009-10-01

A combination of beta spiral and minimum length inverse methods, along with a compilation of historical and recent high-resolution CTD data, are used to produce a quantitative estimate of the subthermocline circulation in Cascadia Basin. Flow in the North Pacific Deep Water, from 900-1900 m, is characterized by a basin-scale anticyclonic gyre. Below 2000 m, two water masses are present within the basin interior, distinguished by different potential temperature-salinity lines. These water masses, referred to as Cascadia Basin Bottom Water (CBBW) and Cascadia Basin Deep Water (CBDW), are separated by a transition zone at about 2400 m depth. Below the depth where it freely communicates with the broader North Pacific, Cascadia Basin is renewed by northward flow through deep gaps in the Blanco Fracture Zone that feeds the lower limb of a vertical circulation cell within the CBBW. Lower CBBW gradually warms and returns to the south at lighter density. Isopycnal layer renewal times, based on combined lateral and diapycnal advective fluxes, increase upwards from the bottom. The densest layer, existing in the southeast quadrant of the basin below ˜2850 m, has an advective flushing time of 0.6 years. The total volume flushing time for the entire CBBW is 2.4 years, corresponding to an average water parcel residence time of 4.7 years. Geothermal heating at the Cascadia Basin seafloor produces a characteristic bottom-intensified temperature anomaly and plays an important role in the conversion of cold bottom water to lighter density within the CBBW. Although covering only about 0.05% of the global seafloor, the combined effects of bottom heat flux and diapycnal mixing within Cascadia Basin provide about 2-3% of the total required global input to the upward branch of the global thermohaline circulation.

Lithospheric-scale centrifuge models of pull-apart basins

Science.gov (United States)

Corti, Giacomo; Dooley, Tim P.

2015-11-01

We present here the results of the first lithospheric-scale centrifuge models of pull-apart basins. The experiments simulate relative displacement of two lithospheric blocks along two offset master faults, with the presence of a weak zone in the offset area localising deformation during strike-slip displacement. Reproducing the entire lithosphere-asthenosphere system provides boundary conditions that are more realistic than the horizontal detachment in traditional 1 g experiments and thus provide a better approximation of the dynamic evolution of natural pull-apart basins. Model results show that local extension in the pull-apart basins is accommodated through development of oblique-slip faulting at the basin margins and cross-basin faults obliquely cutting the rift depression. As observed in previous modelling studies, our centrifuge experiments suggest that the angle of offset between the master fault segments is one of the most important parameters controlling the architecture of pull-apart basins: the basins are lozenge shaped in the case of underlapping master faults, lazy-Z shaped in case of neutral offset and rhomboidal shaped for overlapping master faults. Model cross sections show significant along-strike variations in basin morphology, with transition from narrow V- and U-shaped grabens to a more symmetric, boxlike geometry passing from the basin terminations to the basin centre; a flip in the dominance of the sidewall faults from one end of the basin to the other is observed in all models. These geometries are also typical of 1 g models and characterise several pull-apart basins worldwide. Our models show that the complex faulting in the upper brittle layer corresponds at depth to strong thinning of the ductile layer in the weak zone; a rise of the base of the lithosphere occurs beneath the basin, and maximum lithospheric thinning roughly corresponds to the areas of maximum surface subsidence (i.e., the basin depocentre).

Uranium mobility during interaction of rhyolitic obsidian, perlite and felsite with alkaline carbonate solution: T = 120° C, P = 210 kg/cm2

Science.gov (United States)

Zielinski, Robert A.

1979-01-01

Well-characterized samples of rhyolitic obsidian, perlite and felsite from a single lava flow are leached of U by alkaline oxidizing solutions under open-system conditions. Pressure, temperature, flow rate and solution composition are held constant in order to evaluate the relative importance of differences in surface area and crystallinity. Under the experimental conditions U removal from crushed glassy samples proceeds by a mechanism of glass dissolution in which U and silica are dissolved in approximately equal weight fractions. The rate of U removal from crushed glassy samples increases with decreasing average grain size (surface area). Initial rapid loss of a small component (≈ 2.5%) of the total U from crushed felsite. followed by much slower U loss, reflects variable rates of attack of numerous uranium sites. The fractions of U removed during the experiment ranged from 3.2% (felsite) to 27% (perlite). An empirical method for evaluating the relative rate of U loss from contemporaneous volcanic rocks is presented which incorporates leaching results and rock permeability data.

Age intercalibration of 40Ar/39Ar sanidine and chemically distinct U/Pb zircon populations from the Alder Creek Rhyolite Quaternary geochronology standard

DEFF Research Database (Denmark)

Rivera, Tiffany; Storey, Michael; Schmitz, M. D.

2013-01-01

, and have less pronounced positive Ce and negative Eu anomalies, lower incompatible trace element contents, higher TiZR temperatures that range up to 840 °C, and significantly younger dates. The youngest Group A dates yield a weighted mean of 1.1978 ± 0.0046 Ma (2σ, including systematic uncertainties...... with the astronomical age estimate for the Cobb Mountain subchron determined by correlating the oxygen isotope record of the giant piston core MD972143 to the La93(1,1) orbital solution. On the basis of independent radio-isotopic and orbital forcing results, we propose the refined age of 1.1850 ± 0.0016 Ma (2σ external......We report results from a 40Ar/39Ar sanidine and CA-TIMS 238U/206Pb zircon dating study of eruption and crystal residence timescales of the Alder Creek Rhyolite (ACR), California, extruded during the Cobb Mountain normal-polarity subchron (C1r.2n). A 40Ar/39Ar ACR sanidine date of 1.1850 ± 0.0016 Ma...

The role of Mesozoic sedimentary basin tapers on the formation of Cenozoic crustal shortening structures and foredeep in the western Sichuan Basin, China

Science.gov (United States)

Wang, M.

2017-12-01

The foreland basin records important clues of tectonic and sedimentary process of mountain-building, thus to explore its dynamic mechanism on the formation is an important issue of the mountain-basin interaction. The Longmen Shan fold-and-thrust belt and its adjacent Sichuan basin located in the eastern margin of Tibetan Plateau, are one of the most-concerned regions of studying modern mountain-building and seismic process, and are also a natural laboratory of studying the dynamics of the formation and development of foreland basin. However, it still need further explore on the mechanics of the development of the Cenozoic foreland basin and thrust-belts in the western Sichuan Basin. The Longmen Shan thrust belt has experienced multi-stages of tectonics evolution, foreland basin formation and topography growth since Late Triassic, and whether the early formed basin architecture and large Mesozoic sedimentary basin taper can influence the formation and development of the Cenozoic foreland basin and thrust belts? To solve these issues, this project aim to focus on the Cenozoic foreland basin and internal crustal shortening structures in the western Sichuan basin, on the basis of growth critical wedge taper theory. We will reconstruct the shape of multi-phases of sedimentary basin tapers, the temporal-spatial distribution of crustal shortening and thrusting sequences, and analyze the control mechanism of Mesozoic sedimentary basin taper on the formation of Cenozoic foreland basins, and final explore the interaction between the tectonics geomorphology, stress field and dynamic propagation of foreland basin.

Geochemistry of vanadium in an epigenetic, sandstone-hosted vanadium- uranium deposit, Henry Basin, Utah

Science.gov (United States)

Wanty, R.B.; Goldhaber, M.B.; Northrop, H.R.

1990-01-01

The epigenetic Tony M vanadium-uranium orebody in south-central Utah is hosted in fluvial sandstones of the Morrison Formation (Upper Jurassic). Measurements of the relative amounts of V+3 and V +4 in ore minerals show that V+3 is more abundant. Thermodynamic calculations show that vanadium was more likely transported to the site of mineralization as V+4. The ore formed as V+4 was reduced by hydrogen sulfide, followed by hydrolysis and precipitation of V+3 in oxide minerals or chlorite. Uranium was transported as uranyl ion (U+6), or some complex thereof, and reduced by hydrogen sulfide, forming coffinite. Detrital organic matter in the rocks served as the carbon source for sulfate-reducing bacteria. Vanadium most likely was derived from the dissolution of iron-titanium oxides. Uranium probably was derived from the overlying Brushy Basin Member of the Morrison Formation. Previous studies have shown that the ore formed at the density-stratified interface between a basinal brine and dilute meteoric water. The mineralization processes described above occurred within the mixing zone between these two fluids. -from Authors

Technical knowledge and water resources management: A comparative study of river basin councils, Brazil

Science.gov (United States)

Lemos, Maria Carmen; Bell, Andrew R.; Engle, Nathan L.; Formiga-Johnsson, Rosa Maria; Nelson, Donald R.

2010-06-01

Better understanding of the factors that shape the use of technical knowledge in water management is important both to increase its relevance to decision-making and sustainable governance and to inform knowledge producers where needs lie. This is particularly critical in the context of the many stressors threatening water resources around the world. Recent scholarship focusing on innovative water management institutions emphasizes knowledge use as critical to water systems' adaptive capacity to respond to these stressors. For the past 15 years, water resources management in Brazil has undergone an encompassing reform that has created a set of participatory councils at the river basin level. Using data from a survey of 626 members of these councils across 18 river basins, this article examines the use of technical knowledge (e.g., climate and weather forecasts, reservoir streamflow models, environmental impact assessments, among others) within these councils. It finds that use of knowledge positively aligns with access, a more diverse and broader discussion agenda, and a higher sense of effectiveness. Yet, use of technical knowledge is also associated with skewed levels of power within the councils.

On the significance of ELF basins

Indian Academy of Sciences (India)

Unknown

to complement to chemical intuition (see, e.g., refs. 2, 3). In a mathematically more rigorous way, such regions, ELF basins,4 were defined following the spirit of Bader's Atoms in Molecules (AIM). All points in space which lead to the a given maximum of ELF, by following the gradient of ELF, belong to the same basin. Basins ...

Transient electromagnetic study of basin fill sediments in the Upper San Pedro Basin, Mexico

Science.gov (United States)

Bultman, M.W.; Gray, F.

2011-01-01

The Upper San Pedro River Basin in Mexico and the United States is an important riparian corridor that is coming under increasing pressure from growing populations and the associated increase in groundwater withdrawal. Several studies have produced three-dimensional maps of the basin fill sediments in the US portion of the basin but little work has been done in the Mexican portion of the basin. Here, the results of a ground-based transient electromagnetic (TEM) survey in the Upper San Pedro Basin, Mexico are presented. These basin fill sediments are characterized by a 10-40 m deep unsaturated surficial zone which is composed primarily of sands and gravels. In the central portion of the basin this unsaturated zone is usually underlain by a shallow clay layer 20-50 m thick. Beneath this may be more clay, as is usually the case near the San Pedro River, or interbedded sand, silt, and clay to a depth of 200-250 m. As you move away from the river, the upper clay layer disappears and the amount of sand in the sediments increases. At 1-2 km away from the river, sands can occupy up to 50% of the upper 200-250 m of the sediment fill. Below this, clays are always present except where bedrock highs are observed. This lower clay layer begins at a depth of about 200 m in the central portion of the basin (250 m or more at distances greater than 1-2 km from the river) and extends to the bottom of most profiles to depths of 400 m. While the depth of the top of this lower clay layer is probably accurate, its thickness observed in the models may be overestimated due to the relatively low magnetic moment of the TEM system used in this study. The inversion routine used for interpretation is based on a one-dimensional geologic model. This is a layer based model that is isotropic in both the x and y directions. Several survey soundings did not meet this requirement which invalidates the inversion process and the resulting interpretation at these locations. The results from these

BasinVis 1.0: A MATLAB®-based program for sedimentary basin subsidence analysis and visualization

Science.gov (United States)

Lee, Eun Young; Novotny, Johannes; Wagreich, Michael

2016-06-01

Stratigraphic and structural mapping is important to understand the internal structure of sedimentary basins. Subsidence analysis provides significant insights for basin evolution. We designed a new software package to process and visualize stratigraphic setting and subsidence evolution of sedimentary basins from well data. BasinVis 1.0 is implemented in MATLAB®, a multi-paradigm numerical computing environment, and employs two numerical methods: interpolation and subsidence analysis. Five different interpolation methods (linear, natural, cubic spline, Kriging, and thin-plate spline) are provided in this program for surface modeling. The subsidence analysis consists of decompaction and backstripping techniques. BasinVis 1.0 incorporates five main processing steps; (1) setup (study area and stratigraphic units), (2) loading well data, (3) stratigraphic setting visualization, (4) subsidence parameter input, and (5) subsidence analysis and visualization. For in-depth analysis, our software provides cross-section and dip-slip fault backstripping tools. The graphical user interface guides users through the workflow and provides tools to analyze and export the results. Interpolation and subsidence results are cached to minimize redundant computations and improve the interactivity of the program. All 2D and 3D visualizations are created by using MATLAB plotting functions, which enables users to fine-tune the results using the full range of available plot options in MATLAB. We demonstrate all functions in a case study of Miocene sediment in the central Vienna Basin.

Beyond Colorado's Front Range - A new look at Laramide basin subsidence, sedimentation, and deformation in north-central Colorado

Science.gov (United States)

Cole, James C.; Trexler, James H.; Cashman, Patricia H.; Miller, Ian M.; Shroba, Ralph R.; Cosca, Michael A.; Workman, Jeremiah B.

2010-01-01

This field trip highlights recent research into the Laramide uplift, erosion, and sedimentation on the western side of the northern Colorado Front Range. The Laramide history of the North Park?Middle Park basin (designated the Colorado Headwaters Basin in this paper) is distinctly different from that of the Denver basin on the eastern flank of the range. The Denver basin stratigraphy records the transition from Late Cretaceous marine shale to recessional shoreline sandstones to continental, fluvial, marsh, and coal mires environments, followed by orogenic sediments that span the K-T boundary. Upper Cretaceous and Paleogene strata in the Denver basin consist of two mega-fan complexes that are separated by a 9 million-year interval of erosion/non-deposition between about 63 and 54 Ma. In contrast, the marine shale unit on the western flank of the Front Range was deeply eroded over most of the area of the Colorado Headwaters Basin (approximately one km removed) prior to any orogenic sediment accumulation. New 40Ar-39Ar ages indicate the oldest sediments on the western flank of the Front Range were as young as about 61 Ma. They comprise the Windy Gap Volcanic Member of the Middle Park Formation, which consists of coarse, immature volcanic conglomerates derived from nearby alkalic-mafic volcanic edifices that were forming at about 65?61 Ma. Clasts of Proterozoic granite, pegmatite, and gneiss (eroded from the uplifted core of the Front Range) seem to arrive in the Colorado Headwaters Basin at different times in different places, but they become dominant in arkosic sandstones and conglomerates about one km above the base of the Colorado Headwaters Basin section. Paleocurrent trends suggest the southern end of the Colorado Headwaters Basin was structurally closed because all fluvial deposits show a northward component of transport. Lacustrine depositional environments are indicated by various sedimentological features in several sections within the >3 km of sediment

BASIN ANALYSIS AND PETROLEUM SYSTEM CHARACTERIZATION AND MODELING, INTERIOR SALT BASINS, CENTRAL AND EASTERN GULF OF MEXICO

Energy Technology Data Exchange (ETDEWEB)

Ernest A. Mancini; Donald A. Goddard; Ronald K. Zimmerman

2005-05-10

The principal research effort for Year 2 of the project has been data compilation and the determination of the burial and thermal maturation histories of the North Louisiana Salt Basin and basin modeling and petroleum system identification. In the first nine (9) months of Year 2, the research focus was on the determination of the burial and thermal maturation histories, and during the remainder of the year the emphasis has basin modeling and petroleum system identification. Existing information on the North Louisiana Salt Basin has been evaluated, an electronic database has been developed, regional cross sections have been prepared, structure and isopach maps have been constructed, and burial history, thermal maturation history and hydrocarbon expulsion profiles have been prepared. Seismic data, cross sections, subsurface maps and related profiles have been used in evaluating the tectonic, depositional, burial and thermal maturation histories of the basin. Oil and gas reservoirs have been found to be associated with salt-supported anticlinal and domal features (salt pillows, turtle structures and piercement domes); with normal faulting associated with the northern basin margin and listric down-to-the-basin faults (state-line fault complex) and faulted salt features; and with combination structural and stratigraphic features (Sabine and Monroe Uplifts) and monoclinal features with lithologic variations. Petroleum reservoirs are mainly Upper Jurassic and Lower Cretaceous fluvial-deltaic sandstone facies and Lower Cretaceous and Upper Cretaceous shoreline, marine bar and shallow shelf sandstone facies. Cretaceous unconformities significantly contribute to the hydrocarbon trapping mechanism capacity in the North Louisiana Salt Basin. The chief petroleum source rock in this basin is Upper Jurassic Smackover lime mudstone beds. The generation of hydrocarbons from Smackover lime mudstone was initiated during the Early Cretaceous and continued into the Tertiary

Western Gas Sands Project. Quarterly Basin Activities Report

Energy Technology Data Exchange (ETDEWEB)

Atkinson, C H

1979-01-31

This report is a summation of 3 months' drilling and testing activities in the four primary WGSP study areas: Greater Green River Basin, Northern Great Plains Province, Piceance Basin, and Uinta Basin. The monitoring of basin activities is part of resource assessment. (DLC)

Structuring of The Jurassic Basin of Chott in Gabes region (Southern Tunisia) associated to the Liassic rifting from geophysical and well data

Science.gov (United States)

Hassine, Mouna; Abbes, Chedly; Azaiez, Hajer; Gabtni, Hakim; Bouzid, Wajih

2016-04-01

The graben system of El Hamma, west of Gabes in Tunisia, corresponds to a pull apart basin developed in an extensive relay zone between two principal shear corridors (PSC) with a dextral sliding of N110-120 average direction. These PSC corresponds to two segments of the south-Atlasic shear corridor of NW-SE direction, which extends from Chott El Hodna in Algeria, to the NW, to the Libyan Djeferra to the SE (M.Hassine and al., 2015; M.Hassine and al., work in progress). This work aims to define the basin structuring during the Jurassic, especially from the Upper Lias during the Liassic rifting. For this, we performed seismic, gravity and well data analysis. Several wells situated in this basin and on its edges, which totally or partly crossed the Jurassic series which were described by several authors (J. Bonnefous, 1972 ; M. Soussi, 2002, 2004). These series corresponds to the Nara formation (PF Burollet, 1956) elevated to a group rank by M. Soussi (2003). It consists of two carbonate units separated by a marl-carbonate and sandstone member, dated successively of lower Lias (Hettangian- lower Pliensbachian.), Toarcian to Callovian and Upper Callovian-Tithonian. The correlation of this Jurassic formations along a North-South transect shows, from the South to the North, a significant variation in facies and thickness of the Jurassic series especially from the Upper Lias. Two resistant moles appears to the Northern and Southern edges of the pull-apart basin of El Hamma. The trend reversal of the lateral evolution of this series take place on the border NW-SE faults of the basin (PSC). The analysis of several seismic lines calibrated to well data, reveals a differentiated structuring inside the pull-apart basin itself, associated on the one hand, to the play of the N160 and N130-140 direction fault network which structure the basin in horsts and grabens of second order ( M. Hassine and al., 2015); and on the other hand, to the rise of the upper Triassic evaporates

New TNX Seepage Basin: Environmental information document

International Nuclear Information System (INIS)

Dunaway, J.K.W.; Johnson, W.F.; Kingley, L.E.; Simmons, R.V.; Bledsoe, H.W.

1986-12-01

The New TNX Seepage Basin has been in operation at the Savannah River Plant (SRP) since 1980 and is located in the southeastern section of the TNX facility. The basin receives waste from pilot scale tests conducted at TNX in support of the Defense Waste Processing Facility (DWPF) and the plant Separations area. The basin is scheduled for closure after the TNX Effluent Treatment Plant (ETP) begins operation. The basin will be closed pursuant to all applicable state and federal regulations. A statistical analysis of monitoring data indicates elevated levels of sodium and zinc in the groundwater at this site. Closure options considered for the New TNX Seepage Basin include waste removal and closure, no waste removal and closure, and no action. The two predominant pathways for human exposure to chemical contaminants are through surface, subsurface, and atmospheric transport. Modeling calculations were made to determine the risks to human population via these general pathways for the three postulated closure options for the New TNX Seepage Basin. Cost estimates for each closure option at the basin have also been prepared. An evaluation of the environmental impacts from the New TNX Seepage Basin indicate that the relative risks to human health and ecosystems for the postulated closure options are low. The transport of six chemical and one radionuclide constituents through the environmental pathways from the basin were modeled. The maximum chemical carcinogenic risk and the noncarcinogenic risk for the groundwater pathways were from exposure to trichloromethane and nitrate

Supplementary information on K-Basin sludges

International Nuclear Information System (INIS)

MAKENAS, B.J.

1999-01-01

Three previous documents in this series have been published covering the analysis of: K East Basin Floor and Pit Sludge, K East Basin Canister Sludge, and K West Basin Canister Sludge. Since their publication, additional data have been acquired and analyses performed. It is the purpose of this volume to summarize the additional insights gained in the interim time period

Strike-slip tectonics and Quaternary basin formation along the Vienna Basin fault system inferred from Bouguer gravity derivatives

NARCIS (Netherlands)

Salcher, B. C.; Meurers, B.; Smit, J.; Decker, K.; HöLzel, M.; Wagreich, M.

2012-01-01

The Vienna Basin at the transition between the Alpine and Carpathian belt hosts a number of large Pleistocene sub-basins forming along an active continental scale strike-slip fault (Vienna Basin strike-slip fault). We utilize first-order derivatives from industrial Bouguer gravity data to unravel

A Late Jurassic fossil assemblage in Gondwana: Biostratigraphy and correlations of the Tacuarembó Formation, Parana Basin, Uruguay

Science.gov (United States)

Perea, Daniel; Soto, Matías; Veroslavsky, Gerardo; Martínez, Sergio; Ubilla, Martín

2009-08-01

The Tacuarembó Formation has yielded a fossil assemblage that includes the best known body fossils, consisting of isolated scales, teeth, spines, and molds of bones, recovered from thin and patchy bonebeds, from the Botucatu Desert, Parana Basin, South America. The remains are preserved in the sandstones widespread around the city of Tacuarembó. We propose a new formalized nomenclature for the Tacuarembó Formation, naming its "Lower" and "Upper" members as the Batoví (new name) and Rivera (new rank) members, respectively. An assemblage zone is defined for the Batoví Member (fluviolacustrine and aeolian deposits). In this unit, the freshwater hybodontid shark Priohybodusarambourgi D'Erasmo is well represented. This species was previously recorded in Late Jurassic-Early Cretaceous units of the Sahara and the southern Arabian Peninsula. Globally considered, the fossil assemblage of this member ( P. arambourgi, dipnoan fishes, Ceratosaurus-like theropods, and conchostracans) is indicative of a Kimmeridgian-Tithonian age, which in combination with the stratigraphic relationships of the Tacuarembó Formation with the overlying basalts of the Arapey Formation (132 My average absolute age) implies that the latter was deposited during the Kimmeridgian-Hauterivian interval.

Reconnaissance of promising areas for sandstone type uranium deposits in the Urmia-Naqadeh-Mahabad basin, NW Iran

Directory of Open Access Journals (Sweden)

Mohammad Reza Hezareh

2018-04-01

mineralization and the same as the 8th subbasin there are known deposits of orogenic gold mineralization. 10. Charkeh (104 Km2. The rock units have the NW to SE trend. The anomalies of Zn, Mo, Sn, V, Ni, Au, As and Pb are reported but there is no evidence of mineralization. 11. Sheikh Ebrahim (38 Km2. The anomalies of Mo, Au, As and Pb are reported. The integration of the different layers shows that the prospecting area is suitable for future exploration of blind deposits. Geophysical data was processed and revealed those areas which have data. They can be classified into 5 different classes based on U and Th concentrations. The Hydrogeological data consist of EC, pH, Eh, DO and salinity. And the temperature was measured at the field by Sension 156 multimeter and was sent for ICP-MS analysis to the AMDEL and Applied Geological Research Center (Karaj laboratories. Two samples were obtained from each well by Widel et al.’s (1998 method. One sample was analyzed for Ca2+، Mg2+، Na+، K+، CO32-، HCO3-، SO42-and Cl- and the other samples were analyzed for major and trace elements. At each basin charge, the discharge and the trend of underground water were defined. Results The results revealed that this basin contains alkaline magmatic rocks such as alkaline rhyolite and tuff which are situated in reduced shale and continental volcanic clastic rocks and can be the source of uranium at the study area. Besides these rocks, tuffaceous sandstone, metamorphose sandstone and young alluvial by the reduction condition can be the suitable hosts for mineralization. Based on geological, geochemical, hydrogeological and geophysical data, the western basin is suitable for sandstone type uranium deposit and also there is some evidence of mineralization.

Characteristic mega-basin water storage behavior using GRACE.

Science.gov (United States)

Reager, J T; Famiglietti, James S

2013-06-01

[1] A long-standing challenge for hydrologists has been a lack of observational data on global-scale basin hydrological behavior. With observations from NASA's Gravity Recovery and Climate Experiment (GRACE) mission, hydrologists are now able to study terrestrial water storage for large river basins (>200,000 km 2 ), with monthly time resolution. Here we provide results of a time series model of basin-averaged GRACE terrestrial water storage anomaly and Global Precipitation Climatology Project precipitation for the world's largest basins. We address the short (10 year) length of the GRACE record by adopting a parametric spectral method to calculate frequency-domain transfer functions of storage response to precipitation forcing and then generalize these transfer functions based on large-scale basin characteristics, such as percent forest cover and basin temperature. Among the parameters tested, results show that temperature, soil water-holding capacity, and percent forest cover are important controls on relative storage variability, while basin area and mean terrain slope are less important. The derived empirical relationships were accurate (0.54 ≤  E f  ≤ 0.84) in modeling global-scale water storage anomaly time series for the study basins using only precipitation, average basin temperature, and two land-surface variables, offering the potential for synthesis of basin storage time series beyond the GRACE observational period. Such an approach could be applied toward gap filling between current and future GRACE missions and for predicting basin storage given predictions of future precipitation.

The Members of the Agency

International Nuclear Information System (INIS)

2003-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.58) is Kyrgyzstan, which deposited the instrument of acceptance of the Statute on 10 September 2003. The list shows the dates on which the present 137 Member States became Members

In situ characterization of Hanford K Basins fuel

Energy Technology Data Exchange (ETDEWEB)

Pitner, A.L.

1998-01-06

Irradiated N Reactor uranium metal fuel is stored underwater in the Hanford K East and K West Basins. In K East Basin, fuel is stored in open canisters and defected fuel is free to react with the basin water. In K West Basin, the fuel is stored in sealed canisters filled with water containing a corrosion inhibitor (potassium nitrite). To gain a better understanding of the physical condition of the fuel in these basins, visual surveys using high resolution underwater cameras were conducted. The inspections included detailed lift and look examinations of a number of fuel assemblies from selected canisters in each basin. These examinations formed the bases for selecting specific fuel elements for laboratory testing and analyses as prescribed in the characterization plan for Hanford K Basin Spent Nuclear Fuel.

105-KE basin pilot run relocation

International Nuclear Information System (INIS)

Crystal, J.B.

1994-01-01

The purpose of this document is to present the bases for selecting the exact in-facility location for installation of process equipment to support pilot testing activities in the 105-KE Basin at the United States Department of Energy Hanford Site, in southeastern Washington State. The 105-KE Basin was constructed during the early 1950s, as an integralcomponent of the 105-K East reactor building. Similar basins were provided in all Hanford weapons production reactor buildings to receive fuel elements discharged from the reactors and stage them for rail transport to 200 Area fuel reprocessing plants. The 105-KE reactor began operation in 1955. It was shut down in 1971. However, the 105-KE Basin was reactivated several years later to store spent fuel from the N-Reactor basin and permit its continued operation during outages at the Plutonium Uranium Extraction (PUREX) plant in the 200E Area

Klamath River Basin water-quality data

Science.gov (United States)

Smith, Cassandra D.; Rounds, Stewart A.; Orzol, Leonard L.; Sobieszczyk, Steven

2018-05-29

The Klamath River Basin stretches from the mountains and inland basins of south-central Oregon and northern California to the Pacific Ocean, spanning multiple climatic regions and encompassing a variety of ecosystems. Water quantity and water quality are important topics in the basin, because water is a critical resource for farming and municipal use, power generation, and for the support of wildlife, aquatic ecosystems, and endangered species. Upper Klamath Lake is the largest freshwater lake in Oregon (112 square miles) and is known for its seasonal algal blooms. The Klamath River has dams for hydropower and the upper basin requires irrigation water to support agriculture and grazing. Multiple species of endangered fish inhabit the rivers and lakes, and the marshes are key stops on the Pacific flyway for migrating birds. For these and other reasons, the water resources in this basin have been studied and monitored to support their management distribution.

Basin-scale simulation of current and potential climate changed hydrologic conditions in the Lake Michigan Basin, United States

Science.gov (United States)

Christiansen, Daniel E.; Walker, John F.; Hunt, Randall J.

2014-01-01

The Great Lakes Restoration Initiative (GLRI) is the largest public investment in the Great Lakes in two decades. A task force of 11 Federal agencies developed an action plan to implement the initiative. The U.S. Department of the Interior was one of the 11 agencies that entered into an interagency agreement with the U.S. Environmental Protection Agency as part of the GLRI to complete scientific projects throughout the Great Lakes basin. The U.S. Geological Survey, a bureau within the Department of the Interior, is involved in the GLRI to provide scientific support to management decisions as well as measure progress of the Great Lakes basin restoration efforts. This report presents basin-scale simulated current and forecast climatic and hydrologic conditions in the Lake Michigan Basin. The forecasts were obtained by constructing and calibrating a Precipitation-Runoff Modeling System (PRMS) model of the Lake Michigan Basin; the PRMS model was calibrated using the parameter estimation and uncertainty analysis (PEST) software suite. The calibrated model was used to evaluate potential responses to climate change by using four simulated carbon emission scenarios from eight general circulation models released by the World Climate Research Programme’s Coupled Model Intercomparison Project phase 3. Statistically downscaled datasets of these scenarios were used to project hydrologic response for the Lake Michigan Basin. In general, most of the observation sites in the Lake Michigan Basin indicated slight increases in annual streamflow in response to future climate change scenarios. Monthly streamflows indicated a general shift from the current (2014) winter-storage/snowmelt-pulse system to a system with a more equally distributed hydrograph throughout the year. Simulated soil moisture within the basin illustrates that conditions within the basin are also expected to change on a monthly timescale. One effect of increasing air temperature as a result of the changing

A proposal for an administrative set up of river basin management in the Sittaung River Basin

OpenAIRE

Tun, Zaw Lwin; Ni, Bo; Tun, Sein; Nesheim, Ingrid

2016-01-01

The purpose of this report is to present a proposal for how an administrative approach based on River Basin Management can be implemented in Myanmar. The Sittaung River Basin has been used as an example area to investigate how the basin can be administered according to the IWRM principles of cooperation between the different sectors and the administrative units, including stakeholder involvement. Ministry of Natural Resource and Environmental Conservation, Myanmar Norwegian Ministry of For...

Systematic impact assessment on inter-basin water transfer projects of the Hanjiang River Basin in China

Science.gov (United States)

Zhou, Yanlai; Guo, Shenglian; Hong, Xingjun; Chang, Fi-John

2017-10-01

China's inter-basin water transfer projects have gained increasing attention in recent years. This study proposes an intelligent water allocation methodology for establishing optimal inter-basin water allocation schemes and assessing the impacts of water transfer projects on water-demanding sectors in the Hanjiang River Basin of China. We first analyze water demands for water allocation purpose, and then search optimal water allocation strategies for maximizing the water supply to water-demanding sectors and mitigating the negative impacts by using the Standard Genetic Algorithm (SGA) and Adaptive Genetic Algorithm (AGA), respectively. Lastly, the performance indexes of the water supply system are evaluated under different scenarios of inter-basin water transfer projects. The results indicate that: the AGA with adaptive crossover and mutation operators could increase the average annual water transfer from the Hanjiang River by 0.79 billion m3 (8.8%), the average annual water transfer from the Changjiang River by 0.18 billion m3 (6.5%), and the average annual hydropower generation by 0.49 billion kW h (5.4%) as well as reduce the average annual unmet water demand by 0.40 billion m3 (9.7%), as compared with the those of the SGA. We demonstrate that the proposed intelligent water allocation schemes can significantly mitigate the negative impacts of inter-basin water transfer projects on the reliability, vulnerability and resilience of water supply to the demanding sectors in water-supplying basins. This study has a direct bearing on more intelligent and effectual water allocation management under various scenarios of inter-basin water transfer projects.

Thermal effects in concrete members

International Nuclear Information System (INIS)

Kar, A.K.

1977-01-01

When subjected to temperature changes and restrained from free movement, a member develops stresses. Restrained members are sometimes assumed to act independently of other members. A method of analysis and design for thermal stresses in such members is provided. The method of analysis, based on the ultimate strength concept, greatly reduces the computational efforts for determining thermal effects in concrete members. Available charts and tables and the recommendations given herein simplify the design. (Auth.)

The Members of the Agency

International Nuclear Information System (INIS)

2009-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.67) is Cambodia which deposited its Instrument of Acceptance of the Statute on 23 November 2009. The Attachment hereto shows the dates on which the present 151 Member States became Members [fr

The Members of the Agency

International Nuclear Information System (INIS)

2007-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.63) is Palau which deposited its Instrument of Acceptance of the Statute on 2 March 2007. The Attachment hereto shows the dates on which the present 144 Member States became Members

The Members of the Agency

International Nuclear Information System (INIS)

2009-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.67) is Cambodia which deposited its Instrument of Acceptance of the Statute on 23 November 2009. The Attachment hereto shows the dates on which the present 151 Member States became Members

The Members of the Agency

International Nuclear Information System (INIS)

2008-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.64) is Nepal which deposited its Instrument of Acceptance of the Statute on 8 July 2008. The Attachment hereto shows the dates on which the present 145 Member States became Members

The Members of the Agency

International Nuclear Information System (INIS)

2006-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.62) is Montenegro which deposited its Instrument of Acceptance of the Statute on 30 October 2006. The Attachment hereto shows the dates on which the present 143 Member States became Members

The Members of the Agency

International Nuclear Information System (INIS)

2009-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.67) is Cambodia which deposited its Instrument of Acceptance of the Statute on 23 November 2009. The Attachment hereto shows the dates on which the present 151 Member States became Members [ru

The Members of the Agency

International Nuclear Information System (INIS)

2009-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.67) is Cambodia which deposited its Instrument of Acceptance of the Statute on 23 November 2009. The Attachment hereto shows the dates on which the present 151 Member States became Members [es

The Members of the Agency

International Nuclear Information System (INIS)

2006-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.60) is Chad, which deposited the instrument of acceptance of the Statute on 2 November 2005. The Attachment hereto shows the dates on which the present 139 Member States became Members

Evolution of sedimentary architecture in retro-foreland basin: Aquitaine basin example from Paleocene to lower Eocene.

Science.gov (United States)

Ortega, Carole; Lasseur, Eric; Guillocheau, François; Serrano, Olivier; Malet, David

2017-04-01

The Aquitaine basin located in south western Europe, is a Pyrenean retro-foreland basin. Two main phases of compression are recorded in this retro-foreland basin during the Pyrenean orogeny. A first upper Cretaceous phase corresponding to the early stage of the orogeny, and a second one usually related to a Pyrenean paroxysmal phase during the middle Eocene. During Paleocene to lower Eocene deformations are less pronounced, interpreted as a tectonically quiet period. The aim of the study is to better constrain the sedimentary system of the Aquitaine basin during this period of Paleocene-lower Eocene, in order to discuss the evolution of the sedimentary architecture in response of the Pyrenean compression. This work is based on a compilation of a large set of subsurface data (wells logs, seismic lines and cores logs) represented by isopachs and facies map. Three main cycles were identified during this structural quiet period: (1) The Danian cycle, is recorded by the aggradation of carbonate reef-rimmed platform. This platform is characterized by proximal facies (oncoid carbonate and mudstone with thalassinoides) to the north, which leads to distal deposit facies southern (pelagic carbonate with globigerina and slump facies) and present a significant thickness variation linked to the platform-slope-basin morphology. (2) The upper Selandian-Thanetian cycle follows a non-depositional/erosional surface associated with a Selandian hiatus. The base of this cycle marked the transition between the last reef rimmed platform and a carbonate ramp. The transgressive cycle is characterized by proximal lagoon facies to the north that leads southward to distal hemipelagic facies interfingered by turbiditic Lowstand System Tracks (LST). The location of these LST is strongly controlled by inherited Danian topography. The regressive cycle ends with a major regression associated with an erosional surface. This surface is linked with a network of canyons in the north, an important

The Members of the Agency

International Nuclear Information System (INIS)

2009-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.65) is the Sultanate of Oman which deposited its Instrument of Acceptance of the Statute on 5 February 2009. The Attachment hereto shows the dates on which the present 146 Member States became Members

Petroleum systems in rift basins – a collective approach in South-east Asian basins.

NARCIS (Netherlands)

Doust, H.; Sumner, D.

2007-01-01

This paper synthesizes some of the main conclusions reached in a recent regional review of the Tertiary basins of Southeast Asia, carried out by Shell. Four distinctive types of petroleum systems, correlating with the four main stages of basin evolution (early to late syn-rift and early to late

Preliminary study on features of mineralogical zoning of epigenetic alteration at sandstone-type uranium deposit, Dongsheng area, Ordos basin

International Nuclear Information System (INIS)

Xiao Xinjian; Li Ziying; Chen Anping

2004-01-01

Sandstone-type uranium deposits located in Dongsheng area, northern Ordos basin, occur in Zhiluo Formation, Middle Jurassic. The Zhiluo Formation is divided into two members. The lower member is further divided into two submembers. The lower submember is dominantly composed of grey sandstone being the ore-hosting horizon; the upper submember consists of grey-green sandstone and mudstone. The upper member of Zhiluo Formation is made of mottled medium-fine grained sandstone and mudstone. Through the microscopic observation and study on sandstones of Zhiluo Formation, authors have established a vertical zonation of epigenetic alteration (from the top to the bottom): the limonitization + clayization + carbonation in the mottled fine-grained sandstone of the upper member of Zhiluo Formation; the green alteration (II) (mainly the chloritization of biotite, as well as the chloritization and epidotization of feldspar) + clayization + carbonation in the grey-green sandstone of the upper submember of the lower member of Zhiluo Formation; and the green alteration (I) (mainly the epidotization of feldspar) + carbonation in grey, grey-white sandstone of the lower submember. The epigenetic alteration basically occurs in grey-green sandstone. The sandstone shows grey-green color because it contains much green biotite (not chlorite). The epigenetic alteration in sandstone layer is closely associated with the uranium ore-formation

The Members of the Agency

International Nuclear Information System (INIS)

2009-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.65) is the Sultanate of Oman which deposited its Instrument of Acceptance of the Statute on 5 February 2009. The Attachment hereto shows the dates on which the present 146 Member States became Members [fr

The Members of the Agency

International Nuclear Information System (INIS)

2005-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.59) is the Islamic Republic of Mauritania, which deposited the instrument of acceptance of the Statute on 23 November 2004. The Attachment hereto shows the dates on which the present 138 Member States became Members

The Members of the Agency

International Nuclear Information System (INIS)

2009-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.65) is the Sultanate of Oman which deposited its Instrument of Acceptance of the Statute on 5 February 2009. The Attachment hereto shows the dates on which the present 146 Member States became Members [es

The Donets Basin (Ukraine/Russia): coalification and thermal history.

NARCIS (Netherlands)

Sachsenhofer, R.F.; Privalov, V.A.; Zhykalyak, M.V.; Bueker, C.; Panova, E.A.; Rainer, T.; Shymanovskyy, V.A.; Stephenson, R.A.

2002-01-01

The Donets Basin (Donbas) is one of the major late Paleozoic coal basins in the world. The Donbas Foldbelt is an inverted part of the Donets Basin characterized by WNW-ESE-trending folds and faults. The age of basin inversion is under discussion. Large parts of the Donets Basin host anthracite and

The geologic history of Margaritifer basin, Mars

Science.gov (United States)

Salvatore, M. R.; Kraft, M. D.; Edwards, Christopher; Christensen, P.R.

2016-01-01

In this study, we investigate the fluvial, sedimentary, and volcanic history of Margaritifer basin and the Uzboi-Ladon-Morava (ULM) outflow channel system. This network of valleys and basins spans more than 8000 km in length, linking the fluvially dissected southern highlands and Argyre Basin with the northern lowlands via Ares Vallis. Compositionally, thermophysically, and morphologically distinct geologic units are identified and are used to place critical relative stratigraphic constraints on the timing of geologic processes in Margaritifer basin. Our analyses show that fluvial activity was separated in time by significant episodes of geologic activity, including the widespread volcanic resurfacing of Margaritifer basin and the formation of chaos terrain. The most recent fluvial activity within Margaritifer basin appears to terminate at a region of chaos terrain, suggesting possible communication between surface and subsurface water reservoirs. We conclude with a discussion of the implications of these observations on our current knowledge of Martian hydrologic evolution in this important region.

K Basin Hazard Analysis

Energy Technology Data Exchange (ETDEWEB)

PECH, S.H.

2000-08-23

This report describes the methodology used in conducting the K Basins Hazard Analysis, which provides the foundation for the K Basins Final Safety Analysis Report. This hazard analysis was performed in accordance with guidance provided by DOE-STD-3009-94, Preparation Guide for U. S. Department of Energy Nonreactor Nuclear Facility Safety Analysis Reports and implements the requirements of DOE Order 5480.23, Nuclear Safety Analysis Report.

K Basin Hazard Analysis

International Nuclear Information System (INIS)

PECH, S.H.

2000-01-01

This report describes the methodology used in conducting the K Basins Hazard Analysis, which provides the foundation for the K Basins Final Safety Analysis Report. This hazard analysis was performed in accordance with guidance provided by DOE-STD-3009-94, Preparation Guide for U. S. Department of Energy Nonreactor Nuclear Facility Safety Analysis Reports and implements the requirements of DOE Order 5480.23, Nuclear Safety Analysis Report

Population Structure of Columbia River Basin Chinook Salmon and Steelhead Trout, Technical Report 2001.

Energy Technology Data Exchange (ETDEWEB)

Brannon, E.L.; National Science Foundation (U.S.)

2002-08-01

The population structure of chinook salmon and steelhead trout is presented as an assimilation of the life history forms that have evolved in synchrony with diverse and complex environments over their Pacific range. As poikilotherms, temperature is described as the overwhelming environmental influence that determines what life history options occur and where they are distributed. The different populations represent ecological types referred to as spring-, summer-, fall, and winter-run segments, as well as stream- and ocean-type, or stream- and ocean-maturing life history forms. However, they are more correctly described as a continuum of forms that fall along a temporal cline related to incubation and rearing temperatures that determine spawn timing and juvenile residence patterns. Once new habitats are colonized, members of the founding populations spread through adaptive evolution to assume complementary life history strategies. The related population units are collectively referred to as a metapopulation, and members most closely associated within common temporal and geographic boundaries are designated as first-order metapopulations. Population structure of chinook salmon and steelhead in the Columbia Basin, therefore, is the reflection of the genetic composition of the founding source or sources within the respective region, shaped by the environment, principally temperature, that defines life history evolutionary strategy to maximize fitness under the conditions delineated. The complexity of structure rests with the diversity of opportunities over the elevations that exist within the Basin. Consistent with natural selection, rather than simply attempting to preserve populations, the challenge is to provide opportunities to expand their range to new or restored habitat that can accommodate genetic adaptation as directional environmental changes are elaborated. Artificial propagation can have a critical role in this process, and the emphasis must be placed on

The Agost Basin (Betic Cordillera, Alicante province, Spain): a pull-apart basin involving salt tectonics

Science.gov (United States)

Martín-Martín, Manuel; Estévez, Antonio; Martín-Rojas, Ivan; Guerrera, Francesco; Alcalá, Francisco J.; Serrano, Francisco; Tramontana, Mario

2018-03-01

The Agost Basin is characterized by a Miocene-Quaternary shallow marine and continental infilling controlled by the evolution of several curvilinear faults involving salt tectonics derived from Triassic rocks. From the Serravallian on, the area experienced a horizontal maximum compression with a rotation of the maximum stress axis from E-W to N-S. The resulting deformation gave rise to a strike-slip fault whose evolution is characterized progressively by three stages: (1) stepover/releasing bend with a dextral motion of blocks; (2) very close to pure horizontal compression; and (3) restraining bend with a sinistral movement of blocks. In particular, after an incipient fracturing stage, faults generated a pull-apart basin with terraced sidewall fault and graben subzones developed in the context of a dextral stepover during the lower part of late Miocene p.p. The occurrence of Triassic shales and evaporites played a fundamental role in the tectonic evolution of the study area. The salty material flowed along faults during this stage generating salt walls in root zones and salt push-up structures at the surface. During the purely compressive stage (middle part of late Miocene p.p.) the salt walls were squeezed to form extrusive mushroom-like structures. The large amount of clayish and salty material that surfaced was rapidly eroded and deposited into the basin, generating prograding fan clinoforms. The occurrence of shales and evaporites (both in the margins of the basin and in the proper infilling) favored folding of basin deposits, faulting, and the formation of rising blocks. Later, in the last stage (upper part of late Miocene p.p.), the area was affected by sinistral restraining conditions and faults must have bent to their current shape. The progressive folding of the basin and deformation of margins changed the supply points and finally caused the end of deposition and the beginning of the current erosive systems. On the basis of the interdisciplinary results

Geologic implications of gas hydrates in the offshore of India: Krishna-Godavari Basin, Mahanadi Basin, Andaman Sea, Kerala-Konkan Basin

Digital Repository Service at National Institute of Oceanography (India)

Kumar, P.; Collett, T.S.; Boswell, R.; Cochran, J.R.; Lall, M.; Mazumdar, A.; Ramana, M.V.; Ramprasad, T.; Riedel, M.; Sain, K.; Sathe, A.V.; Vishwanath, K.; Yadav, U.S.

history of the Mahanadi Basin is similar to that of the Krishna-Godavari Basin. The Late Jurassic rift structures along the eastern margin of India cut across older NW-SE-trending Permian-Triassic Gondwana grabens including the Mahanadi and Pranhita...-Godavari grabens (Sastri et al., 1981). The Mahanadi graben appears to have a continuation in Antarctica as the Lambert graben (Federov et al., 1982). These structures served to delineate the fluvial drainage system throughout the evolution of the margin...

Geology and oil and gas assessment of the Fruitland Total Petroleum System, San Juan Basin, New Mexico and Colorado: Chapter 6 in Geology and Oil and Gas Assessment of the Fruitland Total Petroleum System, San Juan Basin, New Mexico and Colorado

Science.gov (United States)

Ridgley, J.L.; Condon, S.M.; Hatch, J.R.

2013-01-01

The Fruitland Total Petroleum System (TPS) of the San Juan Basin Province includes all genetically related hydrocarbons generated from coal beds and organic-rich shales in the Cretaceous Fruitland Formation. Coal beds are considered to be the primary source of the hydrocarbons. Potential reservoir rocks in the Fruitland TPS consist of the Upper Cretaceous Pictured Cliffs Sandstone, Fruitland Formation (both sandstone and coal beds), and the Farmington Sandstone Member of the Kirtland Formation, and the Tertiary Ojo Alamo Sandstone, and Animas, Nacimiento, and San Jose Formations.

The Members of the Agency

International Nuclear Information System (INIS)

2006-01-01

The new Members since the last list of Member States was issued (INFCIRC/2/Rev.61) are Belize, Mozambique and Malawi, which deposited their Instruments of Acceptance of the Statute on 31 March 2006, 18 September 2006 and 2 October 2006 respectively. The Attachment hereto shows the dates on which the present 142 Member States became Members [fr

The Members of the Agency

International Nuclear Information System (INIS)

2006-01-01

The new Members since the last list of Member States was issued (INFCIRC/2/Rev.61) are Belize, Mozambique and Malawi, which deposited their Instruments of Acceptance of the Statute on 31 March 2006, 18 September 2006 and 2 October 2006 respectively. The Attachment hereto shows the dates on which the present 142 Member States became Members

Nature, origin, and production characteristics of the Lower Silurian regional oil and gas accumulation, central Appalachian basin, United States

Science.gov (United States)

Ryder, R.; Zagorski, W.A.

2003-01-01

Low-permeability sandstones of the Lower Silurian regional oil and gas accumulation cover about 45,000 mi2 (117,000 km2) of the Appalachian basin and may contain as much as 30 tcf of recoverable gas resources. Major reservoirs consist of the "Clinton" sandstone and Medina Group sandstones. The stratigraphically equivalent Tuscarora Sandstone increases the area of the Lower Silurian regional accumulation (LSRA) by another 30,000 mi2 (78,000 km2). Approximately 8.7 tcf of gas and 400 million bbl of oil have been produced from the Clinton/Medina reservoirs since 1880. The eastern predominantly gas-bearing part of the LSRA is a basin-center gas accumulation, whereas the western part is a conventional oil and gas accumulation with hybrid features of a basin-center accumulation. The basin-center accumulations have pervasive gas saturation, water near irreducible saturation, and generally low fluid pressures. In contrast, the hybrid-conventional accumulations have less-pervasive oil and gas saturation, higher mobile-water saturation, and both normal and abnormally low fluid pressures. High mobile-water saturation in the hybrid-conventional reservoirs form the updip trap for the basin-center gas creating a broad transition zone, tens of miles wide, that has characteristics of both end-member accumulation types. Although the Tuscarora Sandstone part of the basin-center gas accumulation is pervasively saturated with gas, most of its constituent sandstone beds have low porosity and permeability. Commercial gas fields in the Tuscarora Sandstone are trapped in naturally fractured, faulted anticlines. The origin of the LSRA includes (1) generation of oil and gas from Ordovician black shales, (2) vertical migration through an overlying 1000-ft (305-m)-thick Ordovician shale; (3) abnormally high fluid pressure created by oil-to-gas transformation; (4) updip displacement of mobile pore water by overpressured gas; (5) entrapment of pervasive gas in the basin center; (6) postorogenic

Implementing Integrated River Basin Management in China

NARCIS (Netherlands)

Boekhorst, D.G.J. te; Smits, A.J.M.; Yu, X.; Lifeng, L.; Lei, G.; Zhang, C.

2010-01-01

This paper examines the role of the World Wildlife Fund for Nature China as policy entrepreneur in China. It illustrates the ways in which the World Wildlife Fund for Nature is active in promoting integrated river basin management in the Yangtze River basin and how the efforts at basin level are

The Mackenzie Basin impacts study

International Nuclear Information System (INIS)

Cohen, S.J.

1993-01-01

In 1989, a commitment was made to begin development of a framework for an integrated regional impact assessment of global warming scenarios in the Mackenzie Basin, the most populated region of Canada's north. The project, called Mackenzie Basin Impact Study (MBIS), is led by a multidisciplinary working group from government and non-governmental organizations with interests in the Basin. Objectives of MBIS include defining the direction and magnitude of regional-scale impacts of global warming scenarios on the physical, biological, and human systems of the Basin. MBIS will also identify regional sensitivities to climate, inter-system linkages, uncertainties, policy implications, and research needs. MBIS research activities as of March 1992 are outlined and policy concerns related to global warming are listed. Two new methodologies are being developed by MBIS to address particular economic and policy concerns: a socio-economic resource accounting framework and an integrated land assessment framework. Throughout MBIS, opportunities will be presented for western science and traditional native knowledge to be integrated

77 FR 45653 - Yakima River Basin Conservation Advisory Group; Yakima River Basin Water Enhancement Project...

Science.gov (United States)

2012-08-01

... Basin Conservation Advisory Group, Yakima River Basin Water Enhancement Project, established by the... Water Conservation Program. DATES: The meeting will be held on Tuesday, August 21, 2012, from 1 p.m. to... the implementation of the Water Conservation Program, including the applicable water conservation...

Pedogenic carbonate stable isotopic evidence for wooded habitat preference of early Pleistocene tool makers in the Turkana Basin.

Science.gov (United States)

Quinn, Rhonda L; Lepre, Christopher J; Feibel, Craig S; Wright, James D; Mortlock, Richard A; Harmand, Sonia; Brugal, Jean-Philip; Roche, Hélène

2013-07-01

The origin and evolution of early Pleistocene hominin lithic technologies in Africa occurred within the context of savanna grassland ecosystems. The Nachukui Formation of the Turkana Basin in northern Kenya, containing Oldowan and Acheulean tool assemblages and fossil evidence for early members of Homo and Paranthropus, provides an extensive spatial and temporal paleosol record of early Pleistocene savanna flora. Here we present new carbon isotopic (δ(13)CVPDB) values of pedogenic carbonates (68 nodules, 193 analyses) from the Nachukui Formation in order to characterize past vegetation structure and change through time. We compared three members (Kalochoro, Kaitio, and Natoo) at five locations spanning 2.4-1.4Ma and sampled in proximity to hominin archaeological and paleontological sites. Our results indicate diverse habitats showing a mosaic pattern of vegetation cover at each location yet demonstrate grassland expansion through time influenced by paleogeography. Kalochoro floodplains occurred adjacent to large river systems, and paleosols show evidence of C3 woodlands averaging 46-50% woody cover. Kaitio habitats were located along smaller rivers and lake margins. Paleosols yielded evidence for reduced portions of woody vegetation averaging 34-37% woody cover. Natoo environments had the highest percentage of grasslands averaging 21% woody cover near a diminishing Lake Turkana precursor. We also compared paleosol δ(13)CVPDB values of lithic archaeological sites with paleosol δ(13)CVPDB values of all environments available to hominins at 2.4-1.4Ma in the Nachukui and Koobi Fora Formations. Grassy environments became more widespread during this interval; woody canopy cover mean percentages steadily decreased by 12%. However, significantly more wooded savanna habitats were present in the vicinity of lithic archaeological sites and did not mirror the basin-wide trend of grassland spread. Hominin lithic archaeological sites consistently demonstrated woody cover

The Members of the Agency

International Nuclear Information System (INIS)

2009-01-01

The new Members since the last list of Member States was issued (INFCIRC/2/Rev.66) are Bahrain, Burundi, Congo and Lesotho which deposited their Instruments of Acceptance of the Statute on 23 June 2009, 24 June 2009, 15 July 2009 and 13 July 2009, respectively. The Attachment hereto shows the dates on which the present 150 Member States became Members [fr

The Members of the Agency

International Nuclear Information System (INIS)

2009-01-01

The new Members since the last list of Member States was issued (INFCIRC/2/Rev.66) are Bahrain, Burundi, Congo and Lesotho which deposited their Instruments of Acceptance of the Statute on 23 June 2009, 24 June 2009, 15 July 2009 and 13 July 2009, respectively. The Attachment hereto shows the dates on which the present 150 Member States became Members

The Members of the Agency

International Nuclear Information System (INIS)

2009-01-01

The new Members since the last list of Member States was issued (INFCIRC/2/Rev.66) are Bahrain, Burundi, Congo and Lesotho which deposited their Instruments of Acceptance of the Statute on 23 June 2009, 24 June 2009, 15 July 2009 and 13 July 2009, respectively. The Attachment hereto shows the dates on which the present 150 Member States became Members [ru

The Members of the Agency

International Nuclear Information System (INIS)

2009-01-01

The new Members since the last list of Member States was issued (INFCIRC/2/Rev.66) are Bahrain, Burundi, Congo and Lesotho which deposited their Instruments of Acceptance of the Statute on 23 June 2009, 24 June 2009, 15 July 2009 and 13 July 2009, respectively. The Attachment hereto shows the dates on which the present 150 Member States became Members [es

A review of stratigraphy and sedimentary environments of the Karoo Basin of South Africa

Science.gov (United States)

Smith, R. M. H.

. Deformation of the southern rim of the basin, caused by the subducting palaeo-Pacific plate, resulted in mountain ranges far to the south. Material derived from this source, as well as granitic uplands to the west and morth-east, was deposited on large deltas that built out into the Ecca sea (Upper Ecca). The relatively cool climate and lowland setting promoted thick accumulations of peat on the coastal and delta plains and which now constitute the major coal reserves of southern Africa. Later the prograding deltas coalesced to fill most of the basin after which fluvial sedimentation of the Beaufort Group dominated. The climate by this time (Late Permian) had warmed to become semi-arid with highly seasonal rainfall. The central parts of the basin were for the most part drained by fine-grained meanderbelts and semi-permanent lakes. Significant stratabound uranium reserves have been delimited in the channel sandstones of the Beaufort Group in the southwestern parts of the basin. Pulses of uplift in the southern source areas combined with a possible orogenic effect resulted in two coarser-grained alluvial fans prograding into the more central parts of the basin (Katberg Sandstone Member and Molteno Formation). In the upper Karoo sequence progressive aridification dominated depositional style with playa lake and wadi-type environments (Elliot Formation) that finally gave way to a dune sand dominated system (Clarens Formation). Basinwide volcanic activity of the early Jurassic Drakensberg Group brought deposition in the Karoo Basin to a close.

7 CFR 983.42 - Initial members and nomination of successor members.

Science.gov (United States)

2010-01-01

...) AGRICULTURAL MARKETING SERVICE (Marketing Agreements and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF... alternate is selected shall serve in place of that member on the committee, and shall have and be able to... members of the committee shall serve for terms of two years: Provided, That four of the initially selected...

Episodic Holocene eruption of the Salton Buttes rhyolites, California, from paleomagnetic, U-Th, and Ar/Ar dating

Science.gov (United States)

Wright, Heather M.; Vazquez, Jorge A.; Champion, Duane E.; Calvert, Andrew T.; Mangan, Margaret T.; Stelten, Mark E.; Cooper, Kari M.; Herzig, Charles; Schriener Jr., Alexander

2015-01-01

In the Salton Trough, CA, five rhyolite domes form the Salton Buttes: Mullet Island, Obsidian Butte, Rock Hill, North and South Red Hill, from oldest to youngest. Results presented here include 40Ar/39Ar anorthoclase ages, 238U-230Th zircon crystallization ages, and comparison of remanent paleomagnetic directions with the secular variation curve, which indicate that all domes are Holocene. 238U-230Th zircon crystallization ages are more precise than but within uncertainty of 40Ar/39Ar anorthoclase ages, suggesting that zircon crystallization proceeded until shortly before eruption in all cases except one. Remanent paleomagnetic directions require three eruption periods: (1) Mullet Island, (2) Obsidian Butte, and (3) Rock Hill, North Red Hill, and South Red Hill. Borehole cuttings logs document up to two shallow tephra layers. North and South Red Hills likely erupted within 100 years of each other, with a combined 238U-230Th zircon isochron age of: 2.83 ± 0.60 ka (2 sigma); paleomagnetic evidence suggests this age predates eruption by hundreds of years (1800 cal BP). Rock Hill erupted closely in time to these eruptions. The Obsidian Butte 238U-230Th isochron age (2.86 ± 0.96 ka) is nearly identical to the combined Red Hill age, but its Virtual Geomagnetic Pole position suggests a slightly older age. The age of aphyric Mullet Island dome is the least well constrained: zircon crystals are resorbed and the paleomagnetic direction is most distinct; possible Mullet Island ages include ca. 2300, 5900, 6900, and 7700 cal BP. Our results constrain the duration of Salton Buttes volcanism to between ca. 5900 and 500 years.

Metal Chemical and Isotope Characterisation in the Upper Loire River Basin, France

Science.gov (United States)

Widory, D.; Nigris, R.; Morard, A.; Gassama, N.; Poirier, A.; Bourrain, X.

2016-12-01

The Water Framework Directive (WFD) elaborated by the European Commission regulates water resources in the EC based on five years management plans. A new management plan that started in 2016 imposes strict water quality criteria to its member states, including good status thresholds for metallic contaminants. The Loire River, the most important river in France, flows through areas with lithologies naturally containing high metal concentrations in the upper part of its basin. Understanding these metal fluxes into the river is thus a prerequisite to understand their potential impact on the quality of its water in regards to the criteria defined by the WFD. The Massif Central, a residue of the Hercynian chain, is composed of granitic and volcanic rocks. Both its upstream position in the Loire basin and its numerous metal mineralizations made this region a good candidate for characterizing the natural metal geochemical background of its surface waters. To fulfill this objective we focused on the Pb, Cd and Zn chemical and isotope characteristics of selected non-anthropized small watersheds. The investigated small watersheds were selected for supposedly draining a single lithology and undergoing (as far as possible) negligible to no anthropogenic pressure. Results showed that although the high metal potential of the upper part of the Loire River basin has been highly exploited by humans for centuries, metal concentrations during the hydrological cycle are still under the guidelines defined by the WFD. Isotope compositions/ratios are strongly related to the corresponding lithologies along the rivers and help precisely define the local geochemical background that can then be used to identify and quantify any anthropogenic inputs downstream.

Groundwater quality in the Northern Coast Ranges Basins, California

Science.gov (United States)

Mathany, Timothy M.; Belitz, Kenneth

2015-01-01

The Northern Coast Ranges (NOCO) study unit is 633 square miles and consists of 35 groundwater basins and subbasins (California Department of Water Resources, 2003; Mathany and Belitz, 2015). These basins and subbasins were grouped into two study areas based primarily on locality. The groundwater basins and subbasins located inland, not adjacent to the Pacific Ocean, were aggregated into the Interior Basins (NOCO-IN) study area. The groundwater basins and subbasins adjacent to the Pacific Ocean were aggregated into the Coastal Basins (NOCO-CO) study area (Mathany and others, 2011).

K-Basin isolation barrier seal

International Nuclear Information System (INIS)

Ruff, E.S.

1994-10-01

This report documents various aspects of the design, analysis, procurement, and fabrication of the hydraulic seal on the isolation barriers to be installed in the 100-K Area spent nuclear fuel basin. The isolation barrier is used to keep water in the basin in the event of an earthquake

Gondwana basins and their coal resources in Bangladesh

International Nuclear Information System (INIS)

Nehaluddin, M.; Sultan-ul-Islam, M.

1994-01-01

Fault bounded five Gondwana basins have been discovered in the north western Bangladesh. Among these basins show considerable amount of coal deposits. The Gondwana rocks are highly formed during the Permo-carboniferous diastrophism and later on acquired dynamic characters. In almost all basins, the Permian rocks overlie the Precambrian basement and underlie either the Tertiary or the Cretaceous sediments, structural, stratigraphic, and depositional history of these basins is more or less similar. The sedimentary sequences are composed of light to dark gray, fine to very coarse grained, sub angular to sub rounded felspathic sandstone, dark grey carbonaceous shale and sandstone, variegated conglomerate and thick coal seams (single seam max. 42.38m). The rocks are often alternated and bear the characteristics of cyclic sedimentation. The depositional environments varied from restricted drainage to open fluvial dominated low to moderate sinuous drainage system. The coal bearing basins were flanked by vegetated and swampy over bank. Age of these coals is suggested to be the late permian. Proved and probable reserves of coal in Jamalganj-Paharpur basin are 670 and 1,460 million metric tons, in Barapukuria basin 303 and 3899 million metric tons; in Barapukuria basin 303 and 389 million metric tons; and in Khalaspir basin 143 and 685 million metric tons respectively. The coal is high volatile, low sulphur, bituminous type. It can be used for different forms of thermal conversion. (author)

Characterization of active members in C and N cycles in the subsurface environment of the Witwatersrand Basin

Science.gov (United States)

Lindsay, M. R.; Lau, C. M.; Tetteh, G.; Snyder, L.; Kieft, T. L.; Lollar, B. S.; Li, L.; Maphanga, S.; van Heerden, E.; Onstott, T. C.

2012-12-01

Fracture fluid from various depths and locations in Beatrix gold mine (Gold Fields Ltd.), located in the Welkom region on the 2.9 Ga Witwatersrand Basin of South Africa has been previously studied. Research has shown differential geochemistry data and distinctive community structure which varies from the dominance of different Proteobacterial classes in waters with paleometeoric 18O and 2H signatures including methanotrophs to one dominated by Firmicutes including Candidatus Desulforudis audaxviator-like taxa, which are associated with more saline waters with high concentrations of dissolved H2, hydrocarbons from water-rock reaction and 18O and 2H signatures above the Global Meteoric Water Line. Archaea seem to be a minority and all are euryarchaeota including methanogenic genera. The question is:Which of them are actively driving the subsurface C and N cycles? At shaft 3 on level 26, 1.3 kmbls, fracture water from 42 m behind the tunnel wall located in the Main quartzite formation was collected and analyzed. The temperature, pH, Eh, dissolved O2 and salinity of this hydrocarbon-containing fracture water ranged from 35 to 38°C, 8.2 to 8.8, -30 to -100 mV, 0.3 to 30 μM and 4.2 to 4.3 ppt, respectively. Gas comprised 60% CH4 and 20% N2. The same fracture formerly yielded Halicephalobus mephisto, the first reported subsurface nematode. Microorganisms were captured on filters in two field seasons. Defined by 16S rDNA, 2011 January sample contains β-Proteobacteria (50%), Firmicutes (39%) and α- and γ-Proteobacteria (7%). Of the Firmicutes, 90% were represented by Ca. D. audaxviator. All archaea detected are closestly related to sequences also reported from South African gold mines, with Crenarchaeota accounting for 77% of the clones. Prospective methane-oxidation and production were assessed by amplifying genes encoding for particulate methane monooxygenase alpha subunit (pmoA) and methyl-coenzyme M reductase alpha subunit (mcrA). PmoA genes of Type II

Estimating Stream Discharge of Aboine River Basin of Southeast ...

African Journals Online (AJOL)

ADOWIE PERE

of inter-basin parameters showed that the Aboine drainage basin is basically a flat surface. This ... on the fluvial system and also for predicting the basin output variables. Surface .... outflows of rainwater from the basin as has been done by ...

Geology of the Mid-Miocene Rooster Comb Caldera and Lake Owyhee Volcanic Field, eastern Oregon: Silicic volcanism associated with Grande Ronde flood basalt

Science.gov (United States)

Benson, Thomas R.; Mahood, Gail A.

2016-01-01

The Lake Owyhee Volcanic Field (LOVF) of eastern Oregon consists of rhyolitic caldera centers and lava fields contemporaneous with and spatially related to Mid-Miocene Columbia River flood basalt volcanism. Previous studies delineated two calderas in the southeastern part of LOVF near Owyhee Reservoir, the result of eruptions of two ignimbrites, the Tuff of Leslie Gulch and the Tuff of Spring Creek. Our new interpretation is that these two map units are differentially altered parts of a single ignimbrite produced in a major phreatomagmatic eruption at 15.8 Ma. Areas previously mapped as Tuff of Spring Creek are locations where the ignimbrite contains abundant clinoptilolite ± mordenite, which made it susceptible to erosion. The resistant intracaldera Tuff of Leslie Gulch has an alteration assemblage of albite ± quartz, indicative of low-temperature hydrothermal alteration. Our new mapping of caldera lake sediments and pre- and post-caldera rhyolitic lavas and intrusions that are chemically similar to intracaldera Tuff of Leslie Gulch point to a single 20 × 25 km caldera, which we name the Rooster Comb Caldera. Erosion of the resurgently uplifted southern half of the caldera created dramatic exposures of intracaldera Tuff of Leslie Gulch cut by post-caldera rhyolite dikes and intrusions that are the deeper-level equivalents of lava domes and flows that erupted into the caldera lake preserved in exposures to the northeast. The Rooster Comb Caldera has features in common with more southerly Mid-Miocene calderas of the McDermitt Volcanic Field and High Rock Caldera Complex, including formation in a basinal setting shortly after flood basalt eruptions ceased in the region, and forming on eruption of peralkaline ignimbrite. The volcanism at Rooster Comb Caldera postdates the main activity at McDermitt and High Rock, but, like it, begins 300 ky after flood basalt volcanism begins in the area, and while flood basalts don't erupt through the silicic focus, are

Geomorphological characterization of endorheic basins in northern Chile

Science.gov (United States)

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

2011-12-01

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

Vertical movement in mare basins: relation to mare emplacement, basin tectonics, and lunar thermal history

International Nuclear Information System (INIS)

Solomon, S.C.

1979-01-01

The spatial and temporal relationships of linear rilles and mare ridges in the Serenitatis basin region of the moon are explained by a combination of lithospheric flexure in response to basin loading by basalt fill and a time-dependent global stress due to the thermal evolution of the lunar interior. The pertinent tectonic observations are the radial distance of basin concentric rilles or graben from the mare center; the location and orientation of mare ridges, interpreted as compressive features; and the restriction of graben formation to times older than 3.6 +- 0.2 b.y. ago, while ridge formation continued after emplacement of the youngest mare basalt unit (approx.3 b.y. ago). The locations of the graben are consistent with the geometry of the mare basalt load expected from the dimensions of multiring basins for values of the thickness of the elastic lithosphere beneath Serenitatis in the range 25--50 km at 3.6--3.8 b.y. ago. The locations and orientations of mare ridges are consistent with the load inferred from surface mapping and subsurface radar reflections for values of the elastic lithosphere thickness near 100 km at 3.0--3.4 b.y. ago. The thickening of the lithosphere beneath a major basin during the evolution of mare volcanism is thus clearly evident in the tectonics. The cessation of rille formation and the prolonged period of ridge formation are attributed to a change in the global horizontal thermal stress from extension to compression as the moon shifted from net expansion to overall cooling and contraction. Severe limits as placed on the range of possible lunar thermal histories. The zone of horizontal extensional stresses peripheral to mare loads favors the edge of mare basins as the preferred sites for mare basalt magma eruption in the later stages of mare fill, although subsidence may lead to accumulation of such young lavas in basin centers

Satellite altimetry over large hydrological basins

Science.gov (United States)

Calmant, Stephane

2015-04-01

The use of satellite altimetry for hydrological applications, either it is basin management or hydrological modeling really started with the 21st century. Before, during two decades, the efforts were concentrated on the data processing until a precision of a few decimeters could be achieved. Today, several web sites distribute hundreds of series spread over hundeds of rivers runing in the major basins of the world. Among these, the Amazon basin has been the most widely studied. Satellite altimetry is now routinely used in this transboundary basin to predict discharges ranging over 4 orders of magnitude. In a few years, satellite altimetry should evolve dramatically. This year, we should see the launchs of Jason-3 and that of Sentinel-3A operating in SAR mode. With SAR, the accuracy and resolution of a growing number of measurements should be improved. In 2020, SWOT will provide a full coverage that will join in a unique framework all the previous and forthcoming missions. These technical and thematical evolutions will be illustrated by examples taken in the Amazon and Congo basin.

Two characteristics of planar intertwined basins of attraction

International Nuclear Information System (INIS)

Ding Changming

2012-01-01

Highlights: ► A new mathematical definition of intertwined basins of attraction is proposed. ► Basins are intertwined iff a limit set of stable manifold contains at least two points. ► Basins are intertwined iff the closure of stable manifold is not arc-connected. ► The intertwining property is preserved by topologically equivalent dynamical systems. - Abstract: In this paper, we investigate the intertwined basins of attraction for planar dynamical systems. We prove that the intertwining property is preserved by topologically equivalent systems. Two necessary and sufficient conditions for a planar system having intertwined basins are given.

Climatic controls on arid continental basin margin systems

Science.gov (United States)

Gough, Amy; Clarke, Stuart; Richards, Philip; Milodowski, Antoni

2016-04-01

Alluvial fans are both dominant and long-lived within continental basin margin systems. As a result, they commonly interact with a variety of depositional systems that exist at different times in the distal extent of the basin as the basin evolves. The deposits of the distal basin often cycle between those with the potential to act as good aquifers and those with the potential to act as good aquitards. The interactions between the distal deposits and the basin margin fans can have a significant impact upon basin-scale fluid flow. The fans themselves are commonly considered as relatively homogeneous, but their sedimentology is controlled by a variety of factors, including: 1) differing depositional mechanisms; 2) localised autocyclic controls; 3) geometrical and temporal interactions with deposits of the basin centre; and, 4) long-term allocyclic climatic variations. This work examines the basin margin systems of the Cutler Group sediments of the Paradox Basin, western U.S.A and presents generalised facies models for the Cutler Group alluvial fans as well as for the zone of interaction between these fans and the contemporaneous environments in the basin centre, at a variety of scales. Small-scale controls on deposition include climate, tectonics, base level and sediment supply. It has been ascertained that long-term climatic alterations were the main control on these depositional systems. Models have been constructed to highlight how both long-term and short-term alterations in the climatic regime can affect the sedimentation in the basin. These models can be applied to better understand similar, but poorly exposed, alluvial fan deposits. The alluvial fans of the Brockram Facies, northern England form part of a once-proposed site for low-level nuclear waste decommissioning. As such, it is important to understand the sedimentology, three-dimensional geometry, and the proposed connectivity of the deposits from the perspective of basin-scale fluid flow. The developed

Marketing San Juan Basin gas

International Nuclear Information System (INIS)

Posner, D.M.

1988-01-01

Marketing natural gas produced in the San Juan Basin of New Mexico and Colorado principally involves four gas pipeline companies with significant facilities in the basin. The system capacity, transportation rates, regulatory status, and market access of each of these companies is evaluated. Because of excess gas supplies available to these pipeline companies, producers can expect improved take levels and prices by selling gas directly to end users and utilities as opposed to selling gas to the pipelines for system supply. The complexities of transporting gas today suggest that the services of an independent gas marketing company may be beneficial to smaller producers with gas supplies in the San Juan Basin

Western Canada Sedimentary Basin competitiveness

International Nuclear Information System (INIS)

Millar, R.H.G.

1996-01-01

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

Geochemical characteristics of natural gas in the hydrocarbon accumulation history, and its difference among gas reservoirs in the Upper Triassic formation of Sichuan Basin, China

Directory of Open Access Journals (Sweden)

Peng Wang

2016-08-01

Full Text Available The analysis of hydrocarbon generation, trap formation, inclusion homogenization temperature, authigenic illite dating, and ESR dating were used to understand the history of hydrocarbon accumulation and its difference among gas reservoirs in the Upper Triassic formation of Sichuan Basin. The results show the hydrocarbon accumulation mainly occurred during the Jurassic and Cretaceous periods; they could also be classified into three stages: (1 early hydrocarbon generation accumulation stage, (2 mass hydrocarbon generation accumulation stage before the Himalayan Epoch, (3 and parts of hydrocarbon adjustment and re-accumulation during Himalayan Epoch. The second stage is more important than the other two. The Hydrocarbon accumulation histories are obviously dissimilar in different regions. In western Sichuan Basin, the gas accumulation began at the deposition period of member 5 of Xujiahe Formation, and mass accumulation occurred during the early Middle Jurassic up to the end of the Late Cretaceous. In central Sichuan Basin, the accumulation began at the early Late Jurassic, and the mass accumulation occurred from the middle Early Cretaceous till the end of the Late Cretaceous. In southern Sichuan Basin, the accumulation began at the middle Late Jurassic, and the mass accumulation occurred from the middle of the Late Cretaceous to the end of the Later Cretaceous. The accumulation history of the western Sichuan Basin is the earliest, and the southern Sichuan Basin is the latest. This paper will help to understand the accumulation process, accumulation mechanism, and gas reservoir distribution of the Triassic gas reservoirs in the Sichuan Basin better. Meanwhile, it is found that the authigenic illite in the Upper Triassic formation of Sichuan Basin origin of deep-burial and its dating is a record of the later accumulation. This suggests that the illite dating needs to fully consider illite origin; otherwise the dating results may not accurately

Quaternary volcanism in Deception Island (Antarctica): South Shetland Trench subduction-related signature in the Bransfield Basin back arc domain; Vulcanismo cuaternario de la Isla Decepcion (Antartida): una signatura relacionada con la subduccion de la Fosa de las Shetland del Sur en el dominio de tras-arco de la Cuenca de Bransfield

Energy Technology Data Exchange (ETDEWEB)

Gale, C.; Ubide, T.; Lago, M.; Gil-Imaz, A.; Gil-Pena, I.; Galindo-Zaldivar, J.; Rey, J.; Maestro, A.; Lopez-Martinez, J.

2014-06-01

Deception Island shows a volcanism related to the Phoenix Plate subduction and roll-back under South Shetland Block in the present times. The development of the island is related to the evolution and collapse of a volcanic caldera, and this study is focused on the petrology, mineralogy and geochemistry of the post-caldera rocks. We have made a study of the lava flows, dikes and the youngest historic eruption in 1970. These rocks range from dacite to rhyolite and have a microporphyritic texture with olivine and minor clinopyroxene. A pre-caldera basaltic andesite has also been studied. It has a microporphyritic texture with clinopyroxene. The intermediate and acid compositions alternating in the volcanostratigraphic sequence suggest either mafic recharge events or melt extraction from different levels in the deep magmatic system. All the studied compositions share a subduction-related signature similar to other magmatics from the Bransfield Basin. However, compositional differences between pre-caldera and post-caldera rocks indicate a different magma source and depth of crystallisation. According to the geothermobarometric calculations the pre-caldera magmas started to crystallise at deeper levels (13.5-15 km) than the post-caldera magmas (6.2-7.8 km). Specifically, the postcaldera magmas indicate a smaller influence of the subducting slab in the southwestern part of the Bransfield Basin in respect to the available data from other sectors as well as the involvement of crustal contamination in the genesis of the magmas. (Author)

Geodatabase of sites, basin boundaries, and topology rules used to store drainage basin boundaries for the U.S. Geological Survey, Colorado Water Science Center

Science.gov (United States)

Dupree, Jean A.; Crowfoot, Richard M.

2012-01-01

This geodatabase and its component datasets are part of U.S. Geological Survey Digital Data Series 650 and were generated to store basin boundaries for U.S. Geological Survey streamgages and other sites in Colorado. The geodatabase and its components were created by the U.S. Geological Survey, Colorado Water Science Center, and are used to derive the numeric drainage areas for Colorado that are input into the U.S. Geological Survey's National Water Information System (NWIS) database and also published in the Annual Water Data Report and on NWISWeb. The foundational dataset used to create the basin boundaries in this geodatabase was the National Watershed Boundary Dataset. This geodatabase accompanies a U.S. Geological Survey Techniques and Methods report (Book 11, Section C, Chapter 6) entitled "Digital Database Architecture and Delineation Methodology for Deriving Drainage Basins, and Comparison of Digitally and Non-Digitally Derived Numeric Drainage Areas." The Techniques and Methods report details the geodatabase architecture, describes the delineation methodology and workflows used to develop these basin boundaries, and compares digitally derived numeric drainage areas in this geodatabase to non-digitally derived areas. 1. COBasins.gdb: This geodatabase contains site locations and basin boundaries for Colorado. It includes a single feature dataset, called BasinsFD, which groups the component feature classes and topology rules. 2. BasinsFD: This feature dataset in the "COBasins.gdb" geodatabase is a digital container that holds the feature classes used to archive site locations and basin boundaries as well as the topology rules that govern spatial relations within and among component feature classes. This feature dataset includes three feature classes: the sites for which basins have been delineated (the "Sites" feature class), basin bounding lines (the "BasinLines" feature class), and polygonal basin areas (the "BasinPolys" feature class). The feature dataset

Changes in river discharge and hydrograph separation in the upper basins of Yangtze and Yellow Rivers on the Tibetan Plateau

Science.gov (United States)

Ding, Y.

2017-12-01

Systematic changes of river discharge and the concentration-discharge relation were explored to elucidate the response of river discharge to climate change as well as the connectivity of hydrologic and hydrochemical processes using hydrological data during 1956-2015 and chemical data during 2013-2015 at Yanshiping (YSP, 4,538 km2), Tuotuohe (TTH, 15,924 km2) and Zhimenda (ZMD, 137,704 km2) gauging sections in the upper basin of Yangtze River (UBYA), and at Huangheyan (HHY, 20,930 km2), Jimai (JM, 45,019 km2), Jungong (JG, 98,414 km2) and Tangnaihai (TNH, 121,972 km2) gauging sections in the upper basin of Yellow River (UBYE) on the Tibetan Plateau (TP). Results showed that annual discharge in UBYA presents a decreasing trend from 1950s to late 1970s and exhibits an increasing trend since 1970s due to increased temperature and precipitation. However, discharge in UBYE increases from 1950s to 1980s and decrease since late 1980s due to increased temperature and decreased precipitation. Snow/ice meltwater may play an important role on changes in river discharge from the most upper catchments, particularly for periods with increasing temperature, where snow cover, glaciers and frozen soils are widely distributed. Concentration/flux-discharge in discharge was dominated by a well-defined power law relation, with R2 values lower on rising than falling limbs. This finding has important implications for efforts to estimate annual concentrations and export of major solutes from similar catchments in cold regions where only river discharge is available. Concentrations of conservative solutes in discharge resulted from mixing of two end-members at the most upper gauging sections (YSP, TTH and HHY), and three end-members at the lower gauging sections (ZMD, JM, JG and TNH), with relatively constant solute concentrations in end-members. Relationship between the fractional contributions of meltwater and/or precipitation and groundwater and river discharge followed the same relation

Projected Changes to Streamflow Characteristics in Quebec Basins as Simulated by the Canadian Regional Climate Model (CRCM4)

Science.gov (United States)

Huziy, O.; Sushama, L.; Khaliq, M.; Lehner, B.; Laprise, R.; Roy, R.

2011-12-01

According to the Intergovernmental Panel on Climate Change (IPCC, 2007), an intensification of the global hydrological cycle and increase in precipitation for some regions around the world, including the northern mid- to high-latitudes, is expected in future climate. This will have an impact on mean and extreme flow characteristics, which need to be assessed for better development of adaptation strategies. Analysis of the mean and extreme streamflow characteristics for Quebec (North-eastern Canada) basins in current climate and their projected changes in future climate are assessed using a 10 member ensemble of current (1970 - 1999) and future (2041 - 2070) Canadian RCM (CRCM4) simulations. Validation of streamflow characteristics, performed by comparing modeled values with those observed, available from the Centre d'expertise hydrique du Quebec (CEHQ) shows that the model captures reasonably well the high flows. Results suggest increase in mean and 10 year return levels of 1 day high flows, which appear significant for most of the northern basins.

K Basins Hazard Analysis

International Nuclear Information System (INIS)

WEBB, R.H.

1999-01-01

This report describes the methodology used in conducting the K Basins Hazard Analysis, which provides the foundation for the K Basins Safety Analysis Report (HNF-SD-WM-SAR-062/Rev.4). This hazard analysis was performed in accordance with guidance provided by DOE-STD-3009-94, Preparation Guide for U. S. Department of Energy Nonreactor Nuclear Facility Safety Analysis Reports and implements the requirements of DOE Order 5480.23, Nuclear Safety Analysis Report

K West basin isolation barrier leak rate test

International Nuclear Information System (INIS)

Whitehurst, R.; McCracken, K.; Papenfuss, J.N.

1994-01-01

This document establishes the procedure for performing the acceptance test on the two isolation barriers being installed in K West basin. This acceptance test procedure shall be used to: First establish a basin water loss rate prior to installation of the two isolation barriers between the main basin and the discharge chute in K-Basin West. Second, perform an acceptance test to verify an acceptable leakage rate through the barrier seals

VizieR Online Data Catalog: NGC 6802 dwarf cluster members and non-members (Tang+, 2017)

Science.gov (United States)

Tang, B.; Geisler, D.; Friel, E.; Villanova, S.; Smiljanic, R.; Casey, A. R.; Randich, S.; Magrini, L.; San, Roman I.; Munoz, C.; Cohen, R. E.; Mauro, F.; Bragaglia, A.; Donati, P.; Tautvaisiene, G.; Drazdauskas, A.; Zenoviene, R.; Snaith, O.; Sousa, S.; Adibekyan, V.; Costado, M. T.; Blanco-Cuaresma, S.; Jimenez-Esteban, F.; Carraro, G.; Zwitter, T.; Francois, P.; Jofre, P.; Sordo, R.; Gilmore, G.; Flaccomio, E.; Koposov, S.; Korn, A. J.; Lanzafame, A. C.; Pancino, E.; Bayo, A.; Damiani, F.; Franciosini, E.; Hourihane, A.; Lardo, C.; Lewis, J.; Monaco, L.; Morbidelli, L.; Prisinzano, L.; Sacco, G.; Worley, C. C.; Zaggia, S.

2016-11-01

The dwarf stars in NGC 6802 observed by GIRAFFE spectrograph are separated into four tables: 1. cluster members in the lower main sequence; 2. cluster members in the upper main sequence; 3. non-member dwarfs in the lower main sequence; 4. non-member dwarfs in the upper main sequence. The star coordinates, V band magnitude, V-I color, and radial velocity are given. (4 data files).

REPTILE SPECIES COMPOSITION IN THE MIDDLE GURGUÉIA AND COMPARISON WITH INVENTORIES IN THE EASTERN PARNAÍBA RIVER BASIN, STATE OF PIAUÍ, BRAZIL

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CLÁUDIA RENATA MADELLA-AURICCHIO

Full Text Available ABSTRACT The reptile diversity of the Middle Gurguéia River Basin in southern Piauí, Brazil, is little known. The rapid expansion of agriculture in the region is converting the Cerrado and Caatinga into large farming areas, which threatens biodiversity and hastens its loss. In this study, 68 specimens of reptiles from a university collection were examined, comprising 29 species: ten lizards, one amphisbaenian, 15 snakes, two turtles and one crocodilian. They were collected from five locations in the Middle Gurguéia Basin, a region not previously evaluated for reptiles. The most abundant species is a member of Tropidurus. Comparison with eight other areas in the eastern Parnaíba Basin indicated that the diversity of reptiles in the Middle Gurguéia is similar to that in other Caatinga-Cerrado ecotone areas. The reptile assemblage in the eastern Parnaíba Basin comprises 100 species of reptiles: 39 lizards, five amphisbaenians, 50 snakes, four chelonians and two crocodilians. This study expanded the known distributions of some reptiles and recorded the first occurrence of Helicops leopardinus (Schlegel, 1837 for Piauí. A cluster analysis showed that the reptile composition concords with the habitat where species were found, i.e. Cerrado, Caatinga or ecotone. Studies that associate habitat structure with each species are essential to propose efficient strategies for reptile management and conservation for the entire Parnaíba River Basin, mostly in areas that are not yet protected.

The Apollo peak-ring impact basin: Insights into the structure and evolution of the South Pole-Aitken basin

Science.gov (United States)

Potter, Ross W. K.; Head, James W.; Guo, Dijun; Liu, Jianzhong; Xiao, Long

2018-05-01

The 492 km-diameter Apollo impact basin post-dates, and is located at the inner edge of, the ∼2240 km-diameter South Pole-Aitken (SPA) basin, providing an opportunity to assess the SPA substructure and lateral heterogeneity. Gravity Recovery and Interior Laboratory gravity data suggest an average crustal thickness on the floor of SPA of ∼20 km and within the Apollo basin of ∼5 km, yet remote sensing data reveal no conclusive evidence for the presence of exposed mantle material. We use the iSALE shock physics code to model the formation of the Apollo basin and find that the observational data are best fit by the impact of a 40 km diameter body traveling at 15 km/s into 20-40 km thick crustal material. These results strongly suggest that the Apollo impact occurred on ejecta deposits and collapsed crustal material of the SPA basin and could help place constraints on the location, size and geometry of the SPA transient cavity. The peak ring in the interior of Apollo basin is plausibly interpreted to be composed of inwardly collapsed lower crustal material that experienced peak shock pressures in excess of 35 GPa, consistent with remote sensing observations that suggest shocked plagioclase. Proposed robotic and/or human missions to SPA and Apollo would present an excellent opportunity to test the predictions of this work and address many scientific questions about SPA basin evolution and structure.

Orogeny, shear zones, Continental break-Up And 3-D strain relationships. The tectonic history of the Almada sedimentary Basin, Bahia, Brazil; Relacoes entre orogenos, zonas de cisalhamento, quebra continental e deformacoes 3-D. A historia tectonica da Bacia Sedimentar de Almada, Bahia

Energy Technology Data Exchange (ETDEWEB)

Correa-Gomes, Luiz Cesar [Centro Federal de Educacao Tecnologica da Bahia, Salvador, BA (Brazil). Dept. de Ciencias Aplicadas; Universidade Federal da Bahia (UFBA), Salvador (Brazil). Inst. de Geociencias. Dept. de Geologia]. E-mails: gomes@cefetba.br, lccgomes@ufba.br; Dominguez, Jose Maria Landim; Barbosa, Johildo Salomao Figueiredo; Silva, Idney Cavalcanti da; Pinto, Moises Vieira [Universidade Federal da Bahia (UFBA), Campus de Ondina, Salvador (Brazil). Inst. de Geociencias. Dept. de Geologia]. E-mails: jose_landim@uol.com.br; johildo@cpgg.ufba.br; idney25@ig.com.br; geofisica.ufba@gmail.com

2005-12-15

The Almada Basin is a geometric out-pattern member in the group the onshore coastline sedimentary basins of the Bahia State and neighborhoods. This basin differs from the traditional elongated-shape trending Camamu and Reconcavo-Tucano-Jatoba basins, and shows a compact rhombohedral arrangement following N45 deg, N90 deg, N120 deg e N-S structural lineaments. This shape directly or indirectly reflects a specific geological history influenced by the paleoproterozoic and neo proterozoic orogeny, neo proterozoic shear zones and mesozoic super continent break-up. Several sets of fault and fractures were kinematically studied inside and around the basin, and the main stress tensors obtained using inversion methods. The structural study of the Almada Basin allowed to recognize that: the initial tectonic activity was controlled by normal faults, with orthorhombic-rhombohedral 3-D extensional strain pattern, followed by trans tensional ones characterizing the Almada Basin as a poly phasic tectonic basin, and during the transtensive phase this basin was affected by at least two almost orthogonal extensional events, indicating a possible {sigma}{sub 1} orientation inversion during its formation and tectonic evolution. These data are crucial for prospecting groundwater and hydrocarbon in the basin onshore and offshore areas. (author)

Thermal evolution of a hyperextended rift basin, Mauléon Basin, western Pyrenees

Science.gov (United States)

Hart, Nicole R.; Stockli, Daniel F.; Lavier, Luc L.; Hayman, Nicholas W.

2017-06-01

Onshore and offshore geological and geophysical observations and numerical modeling have greatly improved the conceptual understanding of magma-poor rifted margins. However, critical questions remain concerning the thermal evolution of the prerift to synrift phases of thinning ending with the formation of hyperextended crust and mantle exhumation. In the western Pyrenees, the Mauléon Basin preserves the structural and stratigraphic record of Cretaceous extension, exhumation, and sedimentation of the proximal-to-distal margin development. Pyrenean shortening uplifted basement and overlying sedimentary basins without pervasive shortening or reheating, making the Mauléon Basin an ideal locality to study the temporal and thermal evolution of magma-poor hyperextended rift systems through coupling bedrock and detrital zircon (U-Th)/He thermochronometric data from transects characterizing different structural rifting domains. These new data indicate that the basin was heated during early rifting to >180°C with geothermal gradients of 80-100°C/km. The proximal margin recorded rift-related exhumation/cooling at circa 98 Ma, whereas the distal margin remained >180°C until the onset of Paleocene Pyrenean shortening. Lithospheric-scale numerical modeling shows that high geothermal gradients, >80°C/km, and synrift sediments >180°C, can be reached early in rift evolution via heat advection by lithospheric depth-dependent thinning and blanketing caused by the lower thermal conductivity of synrift sediments. Mauléon Basin thermochronometric data and numerical modeling illustrate that reheating of basement and synrift strata might play an important role and should be considered in the future development of conceptual and numerical models for hyperextended magma-poor continental rifted margins.

Submarine landslides in Arctic sedimentation: Canada Basin

Science.gov (United States)

Mosher, David C.; Shimeld, John; Hutchinson, Deborah R.; Lebedova-Ivanova, N; Chapman, C.

2016-01-01

Canada Basin of the Arctic Ocean is the least studied ocean basin in the World. Marine seismic field programs were conducted over the past 6 years using Canadian and American icebreakers. These expeditions acquired more than 14,000 line-km of multibeam bathymetric and multi-channel seismic reflection data over abyssal plain, continental rise and slope regions of Canada Basin; areas where little or no seismic reflection data existed previously. Canada Basin is a turbidite-filled basin with flat-lying reflections correlateable over 100s of km. For the upper half of the sedimentary succession, evidence of sedimentary processes other than turbidity current deposition is rare. The Canadian Archipelago and Beaufort Sea margins host stacked mass transport deposits from which many of these turbidites appear to derive. The stratigraphic succession of the MacKenzie River fan is dominated by mass transport deposits; one such complex is in excess of 132,000 km2 in area and underlies much of the southern abyssal plain. The modern seafloor is also scarred with escarpments and mass failure deposits; evidence that submarine landsliding is an ongoing process. In its latest phase of development, Canada Basin is geomorphologically confined with stable oceanographic structure, resulting in restricted depositional/reworking processes. The sedimentary record, therefore, underscores the significance of mass-transport processes in providing sediments to oceanic abyssal plains as few other basins are able to do.

Relationships between basin architecture, basin closure, and occurrence of sulphide-bearing schists

DEFF Research Database (Denmark)

Kalliomäki, Henrik; Torvela, Taija; Moreau, Julien

2014-01-01

We present field observations from the Palaeoproterozoic volcano-sedimentary Tampere palaeobasin, where the primary structures have been exceptionally well preserved. We use the observations to construct a new tectonic model for the southeastern margin of the Tampere basin during its inversion...... and subsequent closure. The observed volcano-sedimentary and structural features suggest a change in the local structural style from thick-skinned inversion to thin-skinned thrusting, in order to accommodate the crustal shortening during basin closure. Furthermore, it is suggested that there is a genetic...

Metal-rich fluid inclusions provide new insights into unconformity-related U deposits (Athabasca Basin and Basement, Canada)

Science.gov (United States)

Richard, Antonin; Cathelineau, Michel; Boiron, Marie-Christine; Mercadier, Julien; Banks, David A.; Cuney, Michel

2016-02-01

The Paleoproterozoic Athabasca Basin (Canada) hosts numerous giant unconformity-related uranium deposits. The scope of this study is to establish the pressure, temperature, and composition (P-T-X conditions) of the brines that circulated at the base of the Athabasca Basin and in its crystalline basement before, during and after UO2 deposition. These brines are commonly sampled as fluid inclusions in quartz- and dolomite-cementing veins and breccias associated with alteration and U mineralization. Microthermometry and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) data from five deposits (Rabbit Lake, P-Patch, Eagle Point, Millennium, and Shea Creek) complement previously published data for the McArthur River deposit. In all of the deposits investigated, fluid inclusion salinity is between 25 and 40 wt.% NaCl equiv., with compositions displaying a continuum between a "NaCl-rich brine" end-member (Cl > Na > Ca > Mg > K) and a "CaCl2-rich brine" end-member (Cl > Ca ≈ Mg > Na > K). The CaCl2-rich brine has the highest salinity and shows evidence for halite saturation at the time of trapping. The continuum of compositions between the NaCl-rich brine and the CaCl2-rich brine end-members combined with P-T reconstructions suggest anisothermal mixing of the two brines (NaCl-rich brine, 180 ± 30 °C and 800 ± 400 bars; CaCl2-rich brine, 120 ± 30 °C and 600 ± 300 bars) that occurred under fluctuating pressure conditions (hydrostatic to supra-hydrostatic). However, because the two brines were U bearing and therefore oxidized, brine mixing was probably not the driving force for UO2 deposition. Several scenarios are put forward to account for the Cl-Na-Ca-Mg-K composition of the brines, involving combinations of seawater evaporation, halite dissolution, mixing with a halite-dissolution brine, Mg/Ca exchange by dolomitization, Na/Ca exchange by albitization of plagioclase, Na/K exchange by albitization of K-feldspar, and Mg loss by Mg

Detailed bathymetric surveys in the central Indian Basin

Digital Repository Service at National Institute of Oceanography (India)

Kodagali, V.N.; KameshRaju, K.A.; Ramprasad, T.; George, P.; Jaisankar, S.

Over 420,000 line kilometers of echo-sounding data was collected in the Central Indian Basin. This data was digitized, merged with navigation data and a detailed bathymetric map of the Basin was prepared. The Basin can be broadly classified...

The Members of the Agency

International Nuclear Information System (INIS)

1999-01-01

The document lists the 130 Member States of the Agency as of 1 December 1999. The new Member since the last issue of the list (INFCIRC/2/52) is Angola. The dates on which the present 130 Member States became Members, and the state Honduras) whose application for membership of the Agency has been approved by the General Conference but which has not yet deposited an instrument of acceptance of the Statute are given in an Attachment

Large-scale hydrological simulations using the soil water assessment tool, protocol development, and application in the danube basin.

Science.gov (United States)

Pagliero, Liliana; Bouraoui, Fayçal; Willems, Patrick; Diels, Jan

2014-01-01

The Water Framework Directive of the European Union requires member states to achieve good ecological status of all water bodies. A harmonized pan-European assessment of water resources availability and quality, as affected by various management options, is necessary for a successful implementation of European environmental legislation. In this context, we developed a methodology to predict surface water flow at the pan-European scale using available datasets. Among the hydrological models available, the Soil Water Assessment Tool was selected because its characteristics make it suitable for large-scale applications with limited data requirements. This paper presents the results for the Danube pilot basin. The Danube Basin is one of the largest European watersheds, covering approximately 803,000 km and portions of 14 countries. The modeling data used included land use and management information, a detailed soil parameters map, and high-resolution climate data. The Danube Basin was divided into 4663 subwatersheds of an average size of 179 km. A modeling protocol is proposed to cope with the problems of hydrological regionalization from gauged to ungauged watersheds and overparameterization and identifiability, which are usually present during calibration. The protocol involves a cluster analysis for the determination of hydrological regions and multiobjective calibration using a combination of manual and automated calibration. The proposed protocol was successfully implemented, with the modeled discharges capturing well the overall hydrological behavior of the basin. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Simplifying a hydrological ensemble prediction system with a backward greedy selection of members – Part 2: Generalization in time and space

Directory of Open Access Journals (Sweden)

D. Brochero

2011-11-01

Full Text Available An uncertainty cascade model applied to stream flow forecasting seeks to evaluate the different sources of uncertainty of the complex rainfall-runoff process. The current trend focuses on the combination of Meteorological Ensemble Prediction Systems (MEPS and hydrological model(s. However, the number of members of such a HEPS may rapidly increase to a level that may not be operationally sustainable. This paper evaluates the generalization ability of a simplification scheme of a 800-member HEPS formed by the combination of 16 lumped rainfall-runoff models with the 50 perturbed members from the European Centre for Medium-range Weather Forecasts (ECMWF EPS. Tests are made at two levels. At the local level, the transferability of the 9th day hydrological member selection for the other 8 forecast horizons exhibits an 82% success rate. The other evaluation is made at the regional or cluster level, the transferability from one catchment to another from within a cluster of watersheds also leads to a good performance (85% success rate, especially for forecast time horizons above 3 days and when the basins that formed the cluster presented themselves a good performance on an individual basis. Diversity, defined as hydrological model complementarity addressing different aspects of a forecast, was identified as the critical factor for proper selection applications.

Family members' experiences of autopsy

NARCIS (Netherlands)

Oppewal, F; Meyboom-de Jong, B

Background. The experiences of family members will teach us how to handle an autopsy, the ultimate quality assessment tool. Objective. The aim of this study was to determine surviving family members' experience of autopsy. Method. Seven GPs were asked to approach surviving family members of

Evapotranspiration seasonality across the Amazon Basin

Science.gov (United States)

Eiji Maeda, Eduardo; Ma, Xuanlong; Wagner, Fabien Hubert; Kim, Hyungjun; Oki, Taikan; Eamus, Derek; Huete, Alfredo

2017-06-01

Evapotranspiration (ET) of Amazon forests is a main driver of regional climate patterns and an important indicator of ecosystem functioning. Despite its importance, the seasonal variability of ET over Amazon forests, and its relationship with environmental drivers, is still poorly understood. In this study, we carry out a water balance approach to analyse seasonal patterns in ET and their relationships with water and energy drivers over five sub-basins across the Amazon Basin. We used in situ measurements of river discharge, and remotely sensed estimates of terrestrial water storage, rainfall, and solar radiation. We show that the characteristics of ET seasonality in all sub-basins differ in timing and magnitude. The highest mean annual ET was found in the northern Rio Negro basin (˜ 1497 mm year-1) and the lowest values in the Solimões River basin (˜ 986 mm year-1). For the first time in a basin-scale study, using observational data, we show that factors limiting ET vary across climatic gradients in the Amazon, confirming local-scale eddy covariance studies. Both annual mean and seasonality in ET are driven by a combination of energy and water availability, as neither rainfall nor radiation alone could explain patterns in ET. In southern basins, despite seasonal rainfall deficits, deep root water uptake allows increasing rates of ET during the dry season, when radiation is usually higher than in the wet season. We demonstrate contrasting ET seasonality with satellite greenness across Amazon forests, with strong asynchronous relationships in ever-wet watersheds, and positive correlations observed in seasonally dry watersheds. Finally, we compared our results with estimates obtained by two ET models, and we conclude that neither of the two tested models could provide a consistent representation of ET seasonal patterns across the Amazon.

An underground view of the Albuquerque Basin

Energy Technology Data Exchange (ETDEWEB)

Hawley, J.W.; Haase, C.S.; Lozinsky, R.P. [New Mexico Bureau of Mines and Mineral Resources, Socorro, NM (United States)

1995-12-31

Development of valid hydrogeologic models of New Mexico`s ``critical groundwater basins`` has been a long-term objective of the New Mexico Bureau of Mines and Mineral Resources (NMBMMR), a division of New Mexico Tech. The best possible information on basin hydrogeology is needed not only for incorporation in numerical models of groundwater-flow systems, which are necessary for proper management of limited water resources, but also for addressing public concerns relating to a wide range of important environmental issues. In the latter case, a hydrogeologist must be prepared to provide appropriate explanations of why groundwater systems behave physically and chemically as they do in both natural and man-disturbed situations. The paper describes the regional geologic setting, the geologic setting of the Albuquerque Basin, basin- and valley-fill stratigraphy, and the hydrogeologic model of the Albuquerque Basin. 77 refs., 6 figs., 1 tab.

K Basins fuel encapsulation and storage hazard categorization

International Nuclear Information System (INIS)

Porten, D.R.

1994-12-01

This document establishes the initial hazard categorization for K-Basin fuel encapsulation and storage in the 100 K Area of the Hanford site. The Hazard Categorization for K-Basins addresses the potential for release of radioactive and non-radioactive hazardous material located in the K-Basins and their supporting facilities. The Hazard Categorization covers the hazards associated with normal K-Basin fuel storage and handling operations, fuel encapsulation, sludge encapsulation, and canister clean-up and disposal. The criteria categorizes a facility based on total curies per radionuclide located in the facility. Tables 5-3 and 5-4 display the results in section 5.0. In accordance with DOE-STD-1027 and the analysis provided in section 5.0, the K East Basin fuel encapsulation and storage activity and the K West Basin storage are classified as a open-quotes Category 2close quotes Facility

Performance analysis of double basin solar still with evacuated tubes

International Nuclear Information System (INIS)

Hitesh N Panchal; Shah, P. K.

2013-01-01

Solar still is a very simple device, which is used for solar distillation process. In this research work, double basin solar still is made from locally available materials. Double basin solar still is made in such a way that, outer basin is exposed to sun and lower side of inner basin is directly connected with evacuated tubes to increase distillate output and reducing heat losses of a solar still. The overall size of the lower basin is about 1006 mm x 325 mm x 380 mm, the outer basin is about 1006 mm x 536 mm x 100 mm Black granite gravel is used to increase distillate output by reducing quantity of brackish or saline water in the both basins. Several experiments have conducted to determine the performance of a solar still in climate conditions of Mehsana (latitude of 23 degree 59' and longitude of 72 degree 38'), Gujarat, like a double basin solar still alone, double basin solar still with different size black granite gravel, double basin solar still with evacuated tubes and double basin solar still with evacuated tubes and different size black granite gravel. Experimental results show that, connecting evacuated tubes with the lower side of the inner basin increases daily distillate output of 56% and is increased by 60%, 63% and 67% with average 10 mm, 20 mm and 30 mm size black granite gravel. Economic analysis of present double basin solar still is 195 days. (authors)

The Members of the Agency

International Nuclear Information System (INIS)

2003-01-01

The document lists the 135 Member States of the Agency as of 19 March 2003. The new Member since the last issue of the list (INFCIRC/2/56) is the Republic of Honduras. The dates on which the present 135 Member States became Members are given in an Attachment. It also shows the States whose application for membership of the Agency has been approved by the General Conference but which has not yet deposited an instrument of acceptance of the Statute

The Members of the Agency

International Nuclear Information System (INIS)

2002-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.55) is the Republic of Botswana, which deposited the instrument of acceptance of the Statute on 20 March 2002. The Attachment hereto shows the dates on which the present 134 Member States became Members. It also shows the State whose application for membership of the Agency has been approved by the General Conference, but which has not yet deposited an instrument of acceptance of the Statute

The Members of the Agency

International Nuclear Information System (INIS)

2001-01-01

The document lists the 132 Member States of the Agency as of 1 June 2001. The new Members since the last issue of the list (INFCIRC/2/53) are Central African Republic and Azerbaijan. The dates on which the present 132 Member States became Members are given in an Attachment. It also shows the States whose application for membership of the Agency has been approved by the General Conference but which has not yet deposited an instrument of acceptance of the Statute

Geochemistry of the Late Paleozoic cherts in the Youjiang Basin: Implications for the basin evolution

Directory of Open Access Journals (Sweden)

Huang Hu

2013-10-01

Full Text Available We analyzed the major and rare earth element compositions of siliceous deposits from the Upper Devonian Liujiang Formation, Lower Carboniferous Luzhai Formation, Lower–Middle Permian Sidazhai Formation and Tapi Formation, which are widely distributed as bedded cherts in the interplatform basinal successions of the Youjiang Basin. The Liujiang Formation and Luzhai Formation cherts generally have high Al/(Al+Fe+Mn values (0.38–0.94 and are non-hydrothermal cherts. These cherts are generally characterized by moderately negative Ce anomalies and high Y/Ho values relatived to PAAS, indicating that the Youjiang Basin might have evolved into an open rift basin during the Late Devonian–Early Carboniferous. The Sidazhai Formation cherts from Ziyun generally have high Al/(Al+Fe+Mn values (0.60–0.78, suggesting negligible contribution from a hydrothermal component. The Sidazhai Formation cherts from Hechi and the Tapi Formation cherts from Malipo generally have low Al/(Al+Fe+Mn values (0.09–0.41, indicating an intense hydrothermal input. Relatived to the Sidazhai Formation cherts, the Tapi Formation cherts have higher Ce/Ce* values (0.68±0.19 and lower Y/Ho values (41.83±13.27, which may be affected by the terrigenous input from the Vietnam Block. The Sidazhai Formation cherts from Ziyun and Hechi exhibit negative Ce anomalies (0.43±0.12, 0.33±0.17, respectively with high Y/Ho values (57.44±16.20, 46.02±4.27, respectively, resembling the geochemical characteristics of open-ocean basin cherts. These cherts were deposited on a passive continental margin adjacent to the Babu branch ocean, which may have contributed to upwelling. Detailed spatial studies on geochemical characteristics of the Late Paleozoic cherts can unravel the evolution of the Youjiang Basin.

Quantification of water resources uncertainties in the Luvuvhu sub-basin of the Limpopo river basin

Science.gov (United States)

Oosthuizen, N.; Hughes, D.; Kapangaziwiri, E.; Mwenge Kahinda, J.; Mvandaba, V.

2018-06-01

In the absence of historical observed data, models are generally used to describe the different hydrological processes and generate data and information that will inform management and policy decision making. Ideally, any hydrological model should be based on a sound conceptual understanding of the processes in the basin and be backed by quantitative information for the parameterization of the model. However, these data are often inadequate in many sub-basins, necessitating the incorporation of the uncertainty related to the estimation process. This paper reports on the impact of the uncertainty related to the parameterization of the Pitman monthly model and water use data on the estimates of the water resources of the Luvuvhu, a sub-basin of the Limpopo river basin. The study reviews existing information sources associated with the quantification of water balance components and gives an update of water resources of the sub-basin. The flows generated by the model at the outlet of the basin were between 44.03 Mm3 and 45.48 Mm3 per month when incorporating +20% uncertainty to the main physical runoff generating parameters. The total predictive uncertainty of the model increased when water use data such as small farm and large reservoirs and irrigation were included. The dam capacity data was considered at an average of 62% uncertainty mainly as a result of the large differences between the available information in the national water resources database and that digitised from satellite imagery. Water used by irrigated crops was estimated with an average of about 50% uncertainty. The mean simulated monthly flows were between 38.57 Mm3 and 54.83 Mm3 after the water use uncertainty was added. However, it is expected that the uncertainty could be reduced by using higher resolution remote sensing imagery.

M-area basin closure-Savannah River Site

International Nuclear Information System (INIS)

McMullin, S.R.; Horvath, J.G.

1991-01-01

M-Area, on the Savannah River Site, processes raw materials and manufactures fuel and target rods for reactor use. Effluent from these processes were discharged into the M-Area settling basin and Lost Lake, a natural wetland. The closure of this basin began in 1988 and included the removal and stabilization of basin fluids, excavation of all contaminated soils from affected areas and Lost Lake, and placement of all materials in the bottom of the emptied basin. These materials were covered with a RCRA style cap, employing redundant barriers of kaolin clay and geosynthetic material. Restoration of excavated uplands and wetlands is currently underway

Reconnaissance coal study in the Susitna basin, 2014

Science.gov (United States)

David L. LePain,; Stanley, Richard G.; Harun, Nina T.; Helmold, Kenneth T.; Tsigonis, Rebekah

2015-01-01

The Alaska Division of Geological & Geophysical Surveys (DGGS) conducted fieldwork during the summer of 2014 in the Susitna basin as part of an ongoing evaluation of the hydrocarbon potential of frontier basins, particularly those near the Railbelt region (for example, Decker and others, 2013; Gillis and others, 2013). Topical studies associated with this recent work include sedimentary facies analysis (LePain and others, 2015) and structural geology investigations (Gillis and others, 2015). The Susitna basin contains coal-bearing Paleogene and Neogene strata correlative with formations that host oil and gas in Cook Inlet basin to its south. Isotopic signatures of natural gas reservoired in the Miocene/Pliocene Sterling and Miocene Beluga Formations suggest a biogenic origin for Cook Inlet gas (Claypool and others, 1980). To assess the biogenic gas potential of the Susitna basin, it is important to obtain information from its coal-bearing units.Characteristics of coal, such as maturity/rank and cleat development are key parameters influencing viability of a biogenic gas system (Laubach and others, 1998). In an early study of the Susitna basin (Beluga–Yentna region), Barnes (1966) identified, analyzed, and recognized potentially valuable subbituminous coal resources at Fairview Mountain, Canyon Creek, and Johnson Creek. Merritt (1990), in a sedimentological study to evaluate surface coal mining potential of the Tertiary rocks of the Susitna basin (Susitna lowland), concluded that the basin contained several billion tons of mineable reserves. This preliminary report offers a brief summary of new information on coals in the Susitna Basin acquired during associated stratigraphic studies (see LePain and others, 2015). 

Evaluation of the quality, thermal maturity and distribution of potential source rocks in the Danish part of the Norwegian–Danish Basin

Directory of Open Access Journals (Sweden)

Kristensen, Lars

2008-11-01

Full Text Available The quality, thermal maturity and distribution of potential source rocks within the Palaeozoic–Mesozoic succession of the Danish part of the Norwegian–Danish Basin have been evaluated on the basis of screening data from over 4000 samples from the pre-Upper Cretaceous succession in 33 wells. The Lower Palaeozoic in the basin is overmature and the Upper Cretaceous – Cenozoic strata have no petroleum generation potential, but the Toarcian marine shales of the Lower Jurassic Fjerritslev Formation (F-III, F-IV members and the uppermost Jurassic – lowermost Cretaceous shales of the Frederikshavn Formation may qualify as potential source rocks in parts of the basin. Neither of these potential source rocks has a basinwide distribution; the present occurrence of the Lower Jurassic shales was primarily determined by regional early Middle Jurassic uplift and erosion. The generation potential of these source rocks is highly variable. The F-III and F-IV members show significant lateral changes in generation capacity, the best-developed source rocks occurring in the basin centre. The combined F-III andF-IV members in the Haldager-1, Kvols-1 and Rønde-1 wells contain ‘net source-rock’ thicknesses (cumulative thickness of intervals with Hydrogen Index (HI >200 mg HC/g TOC of 40 m, 83 m, and 92 m, respectively, displaying average HI values of 294, 369 and 404 mg HC/g TOC. The Mors-1 well contains 123 m of ‘net source rock’ with an average HI of 221 mg HC/g TOC. Parts of the Frederikshavn Formation possess a petroleum generation potential in the Hyllebjerg-1, Skagen-2, Voldum-1 and Terne-1 wells, the latter well containing a c.160 m thick highly oil-prone interval with an average HI of 478 mg HC/g TOC and maximum HI values >500 mg HC/g TOC. The source-rock evaluation suggests that a Mesozoic petroleum system is the most likely in the study area. Two primary plays are possible: (1 the Upper Triassic – lowermost Jurassic Gassum play, and (2the

78 FR 65609 - Medicine Bow-Routt National Forests and Thunder Basin National Grassland; Wyoming; Thunder Basin...

Science.gov (United States)

2013-11-01

... National Grassland; Wyoming; Thunder Basin National Grassland Prairie Dog Amendment Environmental Impact... Cooperating Agencies. No changes to the Proposed Action or Purpose of and Need for Action have been made... alternatives will be analyzed in the Thunder Basin National Grassland Prairie Dog Amendment EIS. The EIS will...

State of stress in exhumed basins and implications for fluid flow: insights from the Illizi Basin, Algeria

KAUST Repository

English, Joseph M.

2017-05-31

The petroleum prospectivity of an exhumed basin is largely dependent on the ability of pre-existing traps to retain oil and gas volumes during and after the exhumation event. Although faults may act as lateral seals in petroleum traps, they may start to become hydraulically conductive again and enable fluid flow and hydrocarbon leakage during fault reactivation. We constrain the present day in situ stresses of the exhumed Illizi Basin in Algeria and demonstrate that the primary north–south and NW–SE (vertical strike-slip) fault systems in the study area are close to critical stress (i.e. an incipient state of shear failure). By contrast, the overpressured and unexhumed Berkine Basin and Hassi Messaoud areas to the north do not appear to be characterized by critical stress conditions. We present conceptual models of stress evolution and demonstrate that a sedimentary basin with benign in situ stresses at maximum burial may change to being characterized by critical stress conditions on existing fault systems during exhumation. These models are supportive of the idea that the breaching of a closed, overpressured system during exhumation of the Illizi Basin may have been a driving mechanism for the regional updip flow of high-salinity formation water within the Ordovician reservoirs during Eocene–Miocene time. This work also has implications for petroleum exploration in exhumed basins. Fault-bounded traps with faults oriented at a high angle to the maximum principal horizontal stress direction in strike-slip or normal faulting stress regimes are more likely to have retained hydrocarbons in exhumed basins than fault-bounded traps with faults that are more optimally oriented for shear failure and therefore have a greater propensity to become critically stressed during exhumation.

Water equivalent of snow survey of the Red River Basin and Heart/Cannonball River Basin, March 1978

International Nuclear Information System (INIS)

Feimster, E.L.

1979-10-01

The water equivalent of accumulated snow was estimated in the Red River and Heart/Cannonball River basins and surrounding areas in North Dakota during the period 8 to 17 March 1978. A total of 570 km were flown, covering a 274 km section of the Red River Basin watershed. These lines had been surveyed in March 1974. Twelve flight lines were flown over the North Dakota side of the Red River from a point 23 km south of the Canadian border southward to the city of Fargo, North Dakota. The eight flight lines flown over the Minnesota side of the Red River extended from 23 km south of the Canadian border southward to Breckenridge, Minnesota. Using six flight lines, a total of 120 km were flown in the Heart/Cannonball River Basin, an area southwest of the city of Bismark, North Dakota. This was the first such flight in the Heart/Cannonball River Basin area. Computed weighted average water equivalents on each flight line in the Red River Basin ranged from 4.8 cm to 12.7 cm of water, averaging 7.6 cm for all lines. In the Heart/Cannonball River Basin, the weighted water equivalent ranged from 8.9 cm to 19.1 cm of water, averaging 12.7 cm for all lines. The method used employs the measurement of the natural gamma rays both before and after snow covers the ground

Value of the principles of ''isolation of basins and their boundaries'' and ''isolation of basins and elevations'' in prospecting for oil and gas in the oil and gas basin of China

Energy Technology Data Exchange (ETDEWEB)

Chzhan, V.; Li, Yu.; Se, M.

1982-01-01

A feature of the Chinese oil and gas basins is their fracturing into a large number (to several dozen in one oil and gas basin) isolated basins which are controlled by fault disorders. In these basins in which thick masses of Mesozoic and mainly Cenozoic sedimentary rocks are developed, the main volumes of source rocks are concentrated. Migration of hydrocarbons usually occurs to short distances not exceeding tens of kilometers. From the experience of prospecting and exploration back in the 1950's it was established that thick masses in the central zones of the basins are favorable for processes of hydrocarbon generation, while accumulation occurs in the elevated peripheral parts of the basins and in the regions of the central elevations. The zones of articulation of the central elevations and the edges of the basins are very promising for prospecting for local structures. Examples of large fields which are subordinate to these laws are the largest oil fields in China, Lyakhoe, Dagan and Shenli which are located along the edges of the Bokhayvan basin in the North Chinese oil and gas basin and the Datsin field which is confined to the central elevation of the Sunlyao basin.

Ecohydrological Controls on Intra-Basin Alpine Subarctic Water Balances

Science.gov (United States)

Carey, S. K.; Ziegler, C. M.

2007-12-01

In the mountainous Canadian subarctic, elevation gradients control the disposition of vegetation, permafrost, and characteristics of the soil profile. How intra-basin ecosystems combine to control catchment-scale water and biogeochimcal cycling is uncertain. To this end, a multi-year ecohydrological investigation was undertaken in Granger Basin (GB), a 7.6 km2 sub-basin of the Wolf Creek Research Basin, Yukon Territory, Canada. GB was divided into four sub-basins based on the dominant vegetation and permafrost status, and the timing and magnitude of hydrological processes were compared using hydrometric and hydrochemical methods. Vegetation plays an important role in end-of-winter snow accumulation as snow redistribution by wind is controlled by roughness length. In sub-basins of GB with tall shrubs, snow accumulation is enhanced compared with areas of short shrubs and tundra vegetation. The timing of melt was staggered with elevation, although melt-rates were similar among the sub-basins. Runoff was enhanced at the expense of infiltration in tall shrub areas due to high snow water equivalent and antecedent soil moisture. In the high-elevation tundra sub-basin, thin soils with cold ground temperatures resulted in increased surface runoff. For the freshet period, the lower and upper sub-basins accounted for 81 % of runoff while accounting for 58 % of the total basin area. Two-component isotopic hydrograph separation revealed that during melt, pre-event water dominated in all sub-basins, yet those with greater permafrost disposition and taller shrubs had increased event-water. Dissolved organic carbon (DOC) spiked prior to peak freshet in each sub-basin except for the highest with thin soils, and was associated with flushing of surficial organic soils. For the post-melt period, all sub-basins have similar runoff contributions. Solute and stable isotope data indicate that in sub-basins dominated by permafrost, supra-permafrost runoff pathways predominate as flow

Distribution, Statistics, and Resurfacing of Large Impact Basins on Mercury

Science.gov (United States)

Fassett, Caleb I.; Head, James W.; Baker, David M. H.; Chapman, Clark R.; Murchie, Scott L.; Neumann, Gregory A.; Oberst, Juergen; Prockter, Louise M.; Smith, David E.; Solomon, Sean C.;

Implementing Integrated River Basin Management in China

Directory of Open Access Journals (Sweden)

Dorri G. J. te Boekhorst

2010-06-01

Full Text Available This paper examines the role of the World Wildlife Fund for Nature China as policy entrepreneur in China. It illustrates the ways in which the World Wildlife Fund for Nature is active in promoting integrated river basin management in the Yangtze River basin and how the efforts at basin level are matched with the advice of the China Council for International Cooperation on Environment and Development task force on integrated river basin management to the national government of China. This article demonstrates that the World Wildlife Fund for Nature uses various strategies of different types to support a transition process towards integrated river basin management. Successful deployment of these strategies for change in environmental policy requires special skills, actions, and attitudes on the part of the policy entrepreneur, especially in China, where the government has a dominant role regarding water management and the position of policy entrepeneurs is delicate.

Are calanco landforms similar to river basins?

Science.gov (United States)

Caraballo-Arias, N A; Ferro, V

2017-12-15

In the past badlands have been often considered as ideal field laboratories for studying landscape evolution because of their geometrical similarity to larger fluvial systems. For a given hydrological process, no scientific proof exists that badlands can be considered a model of river basin prototypes. In this paper the measurements carried out on 45 Sicilian calanchi, a type of badlands that appears as a small-scale hydrographic unit, are used to establish their morphological similarity with river systems whose data are available in the literature. At first the geomorphological similarity is studied by identifying the dimensionless groups, which can assume the same value or a scaled one in a fixed ratio, representing drainage basin shape, stream network and relief properties. Then, for each property, the dimensionless groups are calculated for the investigated calanchi and the river basins and their corresponding scale ratio is evaluated. The applicability of Hack's, Horton's and Melton's laws for establishing similarity criteria is also tested. The developed analysis allows to conclude that a quantitative morphological similarity between calanco landforms and river basins can be established using commonly applied dimensionless groups. In particular, the analysis showed that i) calanchi and river basins have a geometrically similar shape respect to the parameters Rf and Re with a scale factor close to 1, ii) calanchi and river basins are similar respect to the bifurcation and length ratios (λ=1), iii) for the investigated calanchi the Melton number assumes values less than that (0.694) corresponding to the river case and a scale ratio ranging from 0.52 and 0.78 can be used, iv) calanchi and river basins have similar mean relief ratio values (λ=1.13) and v) calanchi present active geomorphic processes and therefore fall in a more juvenile stage with respect to river basins. Copyright © 2017 Elsevier B.V. All rights reserved.

Collaborative Adaptation Planning for Water Security: Preliminary Lessons, Challenges, and the Way Forward for Maipo Basin Adaptation Plan, Chile

Science.gov (United States)

Vicuna, S.; Scott, C. A.; Bonelli, S.; Bustos, E.; Meza, F. J.

2014-12-01

The Maipo basin holds 40% of Chile's total population and almost half of the country's Gross Domestic Product. The basin is located in the semiarid central region of the country and, aside from the typical pressures of growth in developing country basins, the Maipo river faces climate change impacts associated with a reduction in total runoff and changes in its seasonality. Surface water is the main water source for human settlements and economic activities including agriculture. In 2012 we started a research project to create a climate variability and climate change adaptation plan for the basin. The pillars of the plan are co-produced by researchers and a Scenario Building Team (SBT) with membership of relevant water and land use stakeholders (including from civil society, public and private sectors) in the basin. Following similar experiences in other regions in the world that have faced the challenges of dealing with long term planning under uncertainty, the project has divided the task of developing the plan into a series of interconnected elements. A critical first component is to work on the desired vision(s) of the basin for the future. In this regards, the "water security" concept has been chosen as a framework that accommodates all objectives of the SBT members. Understanding and quantifying the uncertainties that could affect the future water security of the basin is another critical aspect of the plan. Near and long term climate scenarios are one dimension of these uncertainties that are combined with base development uncertainties such as urban growth scenarios. A third component constructs the models/tools that allows the assessment of impacts on water security that could arise under these scenarios. The final critical component relates to the development of the adaptation measures that could avoid the negative impacts and/or capture the potential opportunities. After two years in the development of the adaptation plan a series of results has been

The members of the Agency

International Nuclear Information System (INIS)

1996-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.46) is Bosnia and Herzegovina. The Attachment hereto shows the dates on which the present 123 Member States became Members. It also shows the States whose applications for membership of the Agency have been approved by the General Conference but which have not yet deposited an instrument of acceptance of the Statute and the State whose application for membership has been recommended by the Board of Governors for approval by the General Conference

The Members of the Agency

International Nuclear Information System (INIS)

1995-01-01

No new Member has joined the Agency since the last list of Member States was issued (INFCIRC/2/Rev.45). The Attachment hereto shows the dates on which the present 122 Member States became Members. It also shows the State whose application for membership of the Agency has been approved by the General Conference but which has not yet deposited an instrument of acceptance of the Statute and the States whose applications for membership have been recommended by the Board of Governors for approval by the General Conference

The Members of the Agency

International Nuclear Information System (INIS)

2003-01-01

The document lists the 136 Member States of the Agency as of 6 May 2003. The new Members since the last issue of the list (INFCIRC/2/57) are Eritrea and the Republic of Seychelles. Cambodia withdrew from the Agency with effect from 26 March 2003. The dates on which the present 136 Member States became Members are given in an Attachment. It also shows the States whose application for membership of the Agency has been approved by the General Conference but which has not yet deposited an instrument of acceptance of the Statute

The Members of the Agency

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-09-11

No new Member has joined the Agency since the last list of Member States was issued (INFCIRC/2/Rev.45). The Attachment hereto shows the dates on which the present 122 Member States became Members. It also shows the State whose application for membership of the Agency has been approved by the General Conference but which has not yet deposited an instrument of acceptance of the Statute and the States whose applications for membership have been recommended by the Board of Governors for approval by the General Conference.

The members of the Agency

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-02-26

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.46) is Bosnia and Herzegovina. The Attachment hereto shows the dates on which the present 123 Member States became Members. It also shows the States whose applications for membership of the Agency have been approved by the General Conference but which have not yet deposited an instrument of acceptance of the Statute and the State whose application for membership has been recommended by the Board of Governors for approval by the General Conference.

Classification of Prairie basins by their hysteretic connected functions

Science.gov (United States)

Shook, K.; Pomeroy, J. W.

2017-12-01

Diagnosing climate change impacts in the post-glacial landscapes of the North American Prairies through hydrological modelling is made difficult by drainage basin physiography. The region is cold, dry and flat with poorly developed stream networks, and so the basin area that is hydrologically connected to the stream outlet varies with basin depressional storage. The connected area controls the contributing area for runoff reaching the stream outlet. As depressional storage fills, ponds spill from one to another; the chain of spilling ponds allows water to flow over the landscape and increases the connected area of the basin. As depressional storage decreases, the connected fraction drops dramatically. Detailed, fine-scale models and remote sensing have shown that the relationship between connected area and the depressional storage is hysteretic in Prairie basins and that the nature of hysteresis varies with basin physiography. This hysteresis needs to be represented in hydrological models to calculate contributing area, and therefore streamflow hydrographs. Parameterisations of the hysteresis are needed for large-scale models used for climate change diagnosis. However, use of parameterisations of hysteresis requires guidance on how to represent them for a particular basin. This study shows that it is possible to relate the shape of hysteretic functions as determined by detailed models to the overall physiography of the basin, such as the fraction of the basin below the outlet, and remote sensing estimates of depressional storage, using the size distribution and location of maximum ponded water areas. By classifying basin physiography, the hysteresis of connected area - storage relationships can be estimated for basins that do not have high-resolution topographic data, and without computationally-expensive high-resolution modelling.

Petroleum prospectivity of the Canada Basin, Arctic Ocean

Science.gov (United States)

Grantz, A.; Hart, P.E.

2011-01-01

Reconnaissance seismic reflection data indicate that Canada Basin is a remnant of the Amerasia Basin of the Arctic Ocean that lies south of the Alpha-Mendeleev Large Igneous Province, which was constructed on the northern part of the Amerasia Basin between about 127 and 89-75 Ma. Canada Basin is filled with Early Jurassic to Holocene detritus from the Mackenzie River system, which drains the northern third of interior North America, with sizable contributions from Alaska and Northwest Canada. Except for the absence of a salt- and shale-bearing mobile substrate Canada Basin is analogous to the Mississippi Delta and the western Gulf of Mexico. Canada Basin contains about 7 to >14 km of sediment beneath the Mackenzie Prodelta on the southeast, 6 to 7 km of sediment beneath the abyssal plain on the west, and roughly 5 or 6 million cubic km of sediment. About three fourths of the basin fill generates low amplitude seismic reflections, interpreted to represent hemiplegic deposits, and a fourth of the fill generates interbedded lenses to extensive layers of moderate to high amplitude reflections interpreted to represent unconfined turbidite and amalgamated channel deposits. Extrapolation from Arctic Alaska and Northwest Canada suggests that three fourths of the section in Canada Basin may contain intervals of hydrocarbon source rocks and the apparent age of the basin suggests that it contains three of the six stratigraphic intervals that together provided >90?? of the World's discovered reserves of oil and gas.. Worldwide heat flow averages suggest that about two thirds of Canada Basin lies in the oil or gas window. At least five types of structural or stratigraphic features of local to regional occurrence offer exploration targets in Canada Basin. These consist of 1) a belt of late Eocene to Miocene shale-cored detachment folds containing with at least two anticlines that are capped by beds with bright spots, 2) numerous moderate to high amplitude reflection packets

Petroleum geology framework, southeast Bowser Basin, British Columbia

Energy Technology Data Exchange (ETDEWEB)

Haggart, J.W. [Geological Survey of Canada, Vancouver, BC (Canada); Mahoney, J.B. [Wisconsin Univ., Eau Claire, WS (United States). Dept. of Geology

2003-07-01

There are significant coal resources in the northern regions of the Bowser basin in north-central British Columbia. However, the resource potential of the southern part of the basin has not been assessed, therefore the hydrocarbon potential is not known. Geological maps indicate several Mesozoic clastic and volcanic units across the southern part of the basin. Two stratigraphic intervals of the southern Bowser basin are considered to be potential source rocks within the Jurassic-Cretaceous strata. The fine-grained clastic rocks of the Bowser Lake Group contain significant amounts of carbonaceous material or organic matter. Well developed cleavage indicates that the rocks may be thermally over mature. This paper described potential reservoir rocks within the basin, along with their thermal maturation and conceptual play. 4 figs.

Petroleum prospectivity of the Canada Basin, Arctic Ocean

Science.gov (United States)

Grantz, Arthur; Hart, Patrick E.

2012-01-01

Reconnaissance seismic reflection data indicate that Canada Basin is a >700,000 sq. km. remnant of the Amerasia Basin of the Arctic Ocean that lies south of the Alpha-Mendeleev Large Igneous Province, which was constructed across the northern part of the Amerasia Basin between about 127 and 89-83.5 Ma. Canada Basin was filled by Early Jurassic to Holocene detritus from the Beaufort-Mackenzie Deltaic System, which drains the northern third of interior North America, with sizable contributions from Alaska and Northwest Canada. The basin contains roughly 5 or 6 million cubic km of sediment. Three fourths or more of this volume generates low amplitude seismic reflections, interpreted to represent hemipelagic deposits, which contain lenses to extensive interbeds of moderate amplitude reflections interpreted to represent unconfined turbidite and amalgamated channel deposits.Extrapolation from Arctic Alaska and Northwest Canada suggests that three fourths of the section in Canada Basin is correlative with stratigraphic sequences in these areas that contain intervals of hydrocarbon source rocks. In addition, worldwide heat flow averages suggest that about two thirds of Canada Basin lies in the oil or gas windows. Structural, stratigraphic and combined structural and stratigraphic features of local to regional occurrence offer exploration targets in Canada Basin, and at least one of these contains bright spots. However, deep water (to almost 4000 m), remoteness from harbors and markets, and thick accumulations of seasonal to permanent sea ice (until its possible removal by global warming later this century) will require the discovery of very large deposits for commercial success in most parts of Canada Basin. ?? 2011 Elsevier Ltd.

7 CFR 1425.19 - Member cooperatives.

Science.gov (United States)

2010-01-01

... 7 Agriculture 10 2010-01-01 2010-01-01 false Member cooperatives. 1425.19 Section 1425.19... OF AGRICULTURE LOANS, PURCHASES, AND OTHER OPERATIONS COOPERATIVE MARKETING ASSOCIATIONS § 1425.19 Member cooperatives. A CMA may obtain loans or LDP's on behalf of a member cooperative when the member...

Inter-Basin Water Transfer Green Supply Chain Equilibrium and Coordination under Social Welfare Maximization

Directory of Open Access Journals (Sweden)

Zhisong Chen

2018-04-01

Full Text Available The inter-basin water transfer (IBWT projects have quasi-public-welfare characteristics, whose operations should take into account the water green level (WGL and social welfare maximization (SWM. This paper explores the interactions between multiple stakeholders of an IBWT green supply chain through the game-theoretic and coordination research approaches considering the government’s subsidy to the WGL improvement under the SWM. The study and its findings complement the IBWT literature in the area of the green supply chain and social welfare maximization modeling. The analytical modeling results with and without considering the SWM are compared. A numerical analysis for a hypothetical IBWT green supply chain is conducted to draw strategic insights from this study. The research results indicate that (1 If the SWM is not considered, coordination strategy could effectively improve the operations performances of the IBWT supply chain and its members, the consumers’ surplus, and the social welfare when compared with the equilibrium strategy; (2 If the SWM is considered, the IBWT green supply chain and its members have a strong intention to adopt the equilibrium strategy to gain more profits, while the government has a strong intention to encourage the IBWT green supply chain and its members to adopt the coordination strategy to maximize social welfare with a smaller public subsidy; (3 The government’s subsidy policy should be designed and provided to encourage the IBWT green supply chain and its members to improve WGL and pursue the SWM, and a subsidy threshold policy can be designed to maximize social welfare with a lower subsidy budget: only when the IBWT green supply chain and its members adopt the coordination strategy can they get a subsidy from the government.

Hydrogeology of the West Siberian Basin

International Nuclear Information System (INIS)

Foley, M.G.; Bradley, D.J.; Cole, C.R.

1996-01-01

Nuclear fuel cycle activities of the former Soviet Union (FSU) have resulted in extensive radioactive contaminant releases to the environment in western Siberia. We are developing three-dimensional numerical models of the hydrogeology and potential contaminant migration in the West Siberian Basin. We have assumed that ground-water flow in the West Siberian Basin is topographically driven, with recharge to the basin occurring in the highlands on the west, east, and south, and internal discharge localized in numerous river valleys and lakes that ultimately discharge north to the ocean. We are modeling the regional hydrogeology as three-dimensional, steady-state, saturated flow that is recharged from above. We acquired topographic, geologic, hydrostratigraphic, hydrogeologic, and water-balance data for the West Siberian Basin and constructed a regional water table. We correlated and combined 70 different rock types derived from published descriptions of West Siberian Basin rocks into 17 rock types appropriate for assignment of hydrogeologic properties on the basis of spatial heterogeneity and constituent (i.e., sand, silt, and clay) diversity. Examination of resulting three-dimensional assemblages of rock types showed that they were consistent with published and inferred paleogeography and depositional processes. Calibrating the basin's moisture balance (i.e., recharge and discharge) to the derived water table determined plausible input parameter values for unknowns such as hydraulic conductivities. The general directions of calculated ground-water flow suggest that major rivers act as discharge areas, with upwelling below the rivers extending down into the basement rocks, and that ground-water divides that penetrate the entire thickness of the model are evident between major rivers

GRAIL Gravity Observations of the Transition from Complex Crater to Peak-Ring Basin on the Moon: Implications for Crustal Structure and Impact Basin Formation

Science.gov (United States)

Baker, David M. H.; Head, James W.; Phillips, Roger J.; Neumann, Gregory A.; Bierson, Carver J.; Smith, David E.; Zuber, Maria T.

2017-01-01

High-resolution gravity data from the Gravity Recovery and Interior Laboratory (GRAIL) mission provide the opportunity to analyze the detailed gravity and crustal structure of impact features in the morphological transition from complex craters to peak-ring basins on the Moon. We calculate average radial profiles for free-air anomalies and Bouguer anomalies for peak-ring basins, proto-basins, and the largest complex craters. Complex craters and proto-basins have free-air anomalies that are positively correlated with surface topography, unlike the prominent lunar mascons (positive free-air anomalies in areas of low elevation) associated with large basins. The Bouguer gravity anomaly profiles of complex craters are highly irregular, with central positive anomalies that are generally absent or not clearly tied to interior morphology. In contrast, gravity profiles for peak-ring basins (approx. 200 km to 580 km) are much more regular and are highly correlated with surface morphology. A central positive Bouguer anomaly is confined within the peak ring and a negative Bouguer anomaly annulus extends from the edge of the positive anomaly outward to about the rim crest. A number of degraded basins lacking interior peak rings have diameters and gravity patterns similar to those of well-preserved peak-ring basins. If these structures represent degraded peak-ring basins, the number of peak-ring basins on the Moon would increase by more than a factor of two to 34. The gravity anomalies within basins are interpreted to be due to uplift of the mantle confined within the peak ring and an annulus of thickened crust between the peak ring and rim crest. We hypothesize that mantle uplift is influenced by interaction between the transient cavity and the mantle. Further, mascon formation is generally disconnected from the number of basin rings formed and occurs over a wide range of basin sizes. These observations have important implications for models of basin and mascon formation on the

National Program for Inspection of Non-Federal Dams. Williams Pond Dam (CT 00551), Thames River Basin, Lebanon, Connecticut. Phase I Inspection Program.

Science.gov (United States)

1978-10-01

GRA&I UnTucea B WILLIAMS POND DAM ~~1Z~ CT 00551 _ Distribution/ Availabilit Y Codes Avail and/or Dis~tj pecialS RIVER BASIN ~lIILEBANON, COXNNECTICUT...Inspection Report. Alternatives to these recommendations r 1 would include reducing the Williams Pond water levels during expected periods of intense storm...Materials Branch Engi’neering Division FRED J. VNS. Jr., Member Chief, De ’ggn Branch Engineering Division SAUL COOPER, -r Chief, Water Control Branch

Proterozoic intracontinental basin: The Vindhyan example

Indian Academy of Sciences (India)

basins display marked similarities in their lithology, depositional setting and stratigraphic architecture. (Naqvi and Rogers 1987). This note sum- marises the stratigraphy, stratal architecture, sed- imentology and geochronology of the Vindhyan. Supergroup occurring in the Son valley region. (figure 1). 2. The Vindhyan basin.

sedimentology, depositional environments and basin evolution

African Journals Online (AJOL)

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ABSTRACT: The Inter-Trappean coal and oil shale-bearing sedimentation in the Delbi-Moye Basin ... accompanied by passive subsidence. ... margins, whereas the concentration of fine-grained clastic sediments and ..... concentrated at the marginal areas of the basin. .... faults favoured the accumulation of alluvial fan.

Carbonate and lignite cycles in the Ptolemais Basin: Orbital control and suborbital variability (Late Neogene, northern Greece)

Science.gov (United States)

Weber, M. E.; Tougiannidis, N.; Ricken, W.; Rolf, C.; Kleineder, M.; Bertram, N.; Antoniadis, P.

2009-04-01

We recently commenced a project to investigate deep drillings as well as outcrops in the Ptolemais Basin, northern Greece, for paleoenvironmental and paleoclimate change. Specific attention is paid to mining sites Achlada, Vevi, Vegora, Amynteon, North Field, South Field, and Lava. The sediment archive comprises Upper Miocene to Quaternary continental lake deposits (up to 800 m thick) with an extended Lower Pliocene section. The Upper Miocene sections are composed of diatomaceous mud and gray marls. Pliocene lake sediments commence with the Kyrio member (lignite/grey marl), followed by the Theodoxus member (beige marl/lignite), and the Notio member (marl with intercalated sand /lignite). The limnic deposits show striking rhythmic bedding of (mostly) carbonates and lignites, reflecting orbital-induced humidity and temperature changes in this small NW-SE elongated continental basin. First, we retrieved chronometric information by determining magnetic polarity changes on three sites as independent stratigraphic ground-truth in combination with palynological evidence and published data. Then we conducted a number of high-resolution (1 - 6 cm increment), non-destructive measurements to obtain paleoclimate proxies: photospectrometry (colors L, a, b), magnetic susceptibility, and natural gamma. Accordingly, we achieved a multi-proxy insight into paleoclimate and paleoenvironmental evolution at unprecedented temporal resolution (up to a few decades!) over long time series and at a number of key sites. Using the newly-developed ESALab software, we conducted spectral and evolutionary spectral analysis to evaluate the cyclo-stratigraphic development. As for orbital variability, spectral power is concentrated on precession, hemi-precession, and eccentricity, with only minor impact of orbital tilt. We used this information to increase the temporal resolution of our age models by tuning as many precession (insolation) maxima as possible to carbonate minima (lignite maxima

The Members of the Agency

International Nuclear Information System (INIS)

2014-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.76) is Brunei Darussalam, which deposited its instrument of acceptance of the Statute on 18 February 2014. The Attachment hereto shows the dates on which the present 162 Member States deposited instruments of ratification or acceptance of the Statute with the depositary Government [fr

The Members of the Agency

International Nuclear Information System (INIS)

2012-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.71) is Rwanda, which deposited its instrument of acceptance of the Statute on 4 September 2012. The Attachment hereto shows the dates on which the present 155 Member States deposited instruments of ratification or acceptance of the Statute with the depositary Government [fr

The Members of the Agency

International Nuclear Information System (INIS)

2012-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.70) is Papua New Guinea, which deposited its instrument of acceptance of the Statute on 4 April 2012. The Attachment hereto shows the dates on which the present 154 Member States deposited instruments of ratification or acceptance of the Statute with the depositary Government

The Members of the Agency

International Nuclear Information System (INIS)

2013-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.74) is Swaziland, which deposited its instrument of acceptance of the Statute on 15 February 2013. The Attachment hereto shows the dates on which the present 159 Member States deposited instruments of ratification or acceptance of the Statute with the depositary Government

The Members of the Agency

International Nuclear Information System (INIS)

2012-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.71) is Rwanda, which deposited its instrument of acceptance of the Statute on 4 September 2012. The Attachment hereto shows the dates on which the present 155 Member States deposited instruments of ratification or acceptance of the Statute with the depositary Government

The Members of the Agency

International Nuclear Information System (INIS)

2014-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.76) is Brunei Darussalam, which deposited its instrument of acceptance of the Statute on 18 February 2014. The Attachment hereto shows the dates on which the present 162 Member States deposited instruments of ratification or acceptance of the Statute with the depositary Government

The Members of the Agency

International Nuclear Information System (INIS)

2012-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.73) is Trinidad and Tobago, which deposited its instrument of acceptance of the Statute on 9 November 2012. The Attachment hereto shows the dates on which the present 158 Member States deposited instruments of ratification or acceptance of the Statute with the depositary Government

The Members of the Agency

International Nuclear Information System (INIS)

2012-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.71) is Rwanda, which deposited its instrument of acceptance of the Statute on 4 September 2012. The Attachment hereto shows the dates on which the present 155 Member States deposited instruments of ratification or acceptance of the Statute with the depositary Government [es

The Members of the Agency

International Nuclear Information System (INIS)

2014-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.76) is Brunei Darussalam, which deposited its instrument of acceptance of the Statute on 18 February 2014. The Attachment hereto shows the dates on which the present 162 Member States deposited instruments of ratification or acceptance of the Statute with the depositary Government [es

The Members of the Agency

International Nuclear Information System (INIS)

2012-01-01

The new Member since the last list of Member States was issued (INFCIRC/2/Rev.71) is Rwanda, which deposited its instrument of acceptance of the Statute on 4 September 2012. The Attachment hereto shows the dates on which the present 155 Member States deposited instruments of ratification or acceptance of the Statute with the depositary Government [ru

The tritium balance of the Ems river basin

International Nuclear Information System (INIS)

Krause, W.J.

1989-01-01

For the Ems river basin, as a fine example of a Central European lowland basin, an inventory of the tritium distribution is presented for the hydrologic years 1951 to 1983. On the basis of a balance model, the tritium contents in surface waters and groundwater of the Ems river basin are calculated, using known and extrapolated tritium input data and comparing them with the corresponding values measured since 1974. A survey of tritium flows occurring in this basin is presented, taking meteorologic and hydrologic facts into account. (orig.)

Rifting Thick Lithosphere - Canning Basin, Western Australia

Science.gov (United States)

Czarnota, Karol; White, Nicky

2016-04-01

The subsidence histories and architecture of most, but not all, rift basins are elegantly explained by extension of ~120 km thick lithosphere followed by thermal re-thickening of the lithospheric mantle to its pre-rift thickness. Although this well-established model underpins most basin analysis, it is unclear whether the model explains the subsidence of rift basins developed over substantially thick lithosphere (as imaged by seismic tomography beneath substantial portions of the continents). The Canning Basin of Western Australia is an example where a rift basin putatively overlies lithosphere ≥180 km thick, imaged using shear wave tomography. Subsidence modelling in this study shows that the entire subsidence history of the account for the observed subsidence, at standard crustal densities, the lithospheric mantle is required to be depleted in density by 50-70 kg m-3, which is in line with estimates derived from modelling rare-earth element concentrations of the ~20 Ma lamproites and global isostatic considerations. Together, these results suggest that thick lithosphere thinned to > 120 km is thermally stable and is not accompanied by post-rift thermal subsidence driven by thermal re-thickening of the lithospheric mantle. Our results show that variations in lithospheric thickness place a fundamental control on basin architecture. The discrepancy between estimates of lithospheric thickness derived from subsidence data for the western Canning Basin and those derived from shear wave tomography suggests that the latter technique currently is limited in its ability to resolve lithospheric thickness variations at horizontal half-wavelength scales of <300 km.

Juvenile pumice and pyroclastic obsidian reveal the eruptive conditions necessary for the stability of Plinian eruption of rhyolitic magma

Science.gov (United States)

Giachetti, T.; Shea, T.; Gonnermann, H. M.; McCann, K. A.; Hoxsie, E. C.

2016-12-01

Significant explosive activity generally precedes or coexists with the large effusion of rhyolitic lava (e.g., Mono Craters; Medicine Lake Volcano; Newberry; Chaitén; Cordón Caulle). Such explosive-to-effusive transitions and, ultimately, cessation of activity are commonly explained by the overall waning magma chamber pressure accompanying magma withdrawal, albeit modulated by magma outgassing. The tephra deposits of such explosive-to-effusive eruptions record the character of the transition - abrupt or gradual - as well as potential changes in eruptive conditions, such as magma composition, volatiles content, mass discharge rate, conduit size, magma outgassing. Results will be presented from a detailed study of both the gas-rich (pumice) and gas-poor (obsidian) juvenile pyroclasts produced during the Plinian phase of the 1060 CE Glass Mountain eruption of Medicine Lake Volcano, California. In the proximal deposits, a multitude of pumice-rich sections separated by layers rich in dense clasts suggests a pulsatory behavior of the explosive phase. Density measurements on 2,600 pumices show that the intermediate, most voluminous deposits have a near constant median porosity of 65%. However, rapid increase in porosity to 75-80% is observed at both the bottom and the top of the fallout deposits, suggestive of rapid variations in magma degassing. In contrast, a water content of pyroclastic obsidians of approximately 0.6 wt% does remain constant throughout the eruption, suggesting that the pyroclastic obsidians degassed up to a constant pressure of a few megapascals. Numerical modeling of eruptive magma ascent and degassing is used to provide constraints on eruption conditions.

Geochronology of the Turkana depression of northern Kenya and southern Ethiopia.

Science.gov (United States)

Brown, Francis H; McDougall, Ian

2011-01-01

Mesozoic and Cenozoic sedimentary rocks in the Turkana Depression of northern Kenya and southern Ethiopia rest on basement rocks that yield K/Ar cooling ages between 433 and 522 Ma. Proven Cretaceous strata are exposed in Lokitaung Gorge in northwest Kenya. Eocene basalts and rhyolites in Lokitaung Gorge, the Nabwal Hills, and at Kangamajoj, date between 34 and 36 Ma, recording the earliest volcanism in the region. Oligocene volcanic rocks, with associated fossiliferous sedimentary strata at Eragaleit, Nakwai, and Lokone, all west of Lake Turkana, are 23 to 28 Ma old, as is the Langaria Formation east of Lake Turkana. Lower and Middle Miocene volcanic and sedimentary sequences are present both east and west of Lake Turkana, where ages from 17.9 to 9.1 Ma have been measured at many levels. Upper Miocene strata are presently known only at Lothagam, with ages ranging from 7.4 to 6.5 Ma. Deposition of Pliocene strata of the Omo Group begins in the Omo-Turkana, Kerio, and South Turkana basins -4.3 Ma ago and continues in parts of those basins until nearly the present time, but with some gaps. These strata are linked through volcanic ash correlations at many levels, as are Pleistocene strata of the Omo Group (principally the Shungura, Koobi Fora, and Nachukui formations). (40) Ar/(39) Ar dates on many volcanic ash layers within the Omo Group, supplemented by K/Ar ages on intercalated basalts and paleomagnetic polarity stratigraphy, provide excellent age control from 4.2 to 0.75 Ma, although there is a gap in the record between -1 Ma and 0.8 Ma. Members I to III of the Kibish Formation in the lower Omo Valley record deposition between 0.2 and 0.1 Ma ago; Member IV, correlative with the Galana Boi Formation, was deposited principally between 12 and 7 ka BP. Copyright © 2011 Wiley Periodicals, Inc.

Cenozoic North American Drainage Basin Evolution, Sediment Yield, and Accumulation in the Gulf of Mexico Basin

Science.gov (United States)

Galloway, W.; Ganey-Curry, P. E.

2010-12-01

The Cenozoic fill of the Gulf of Mexico basin contains a continuous record of sediment supply from the North American continental interior for the past 65 million years. Regional mapping of unit thickness and paleogeography for 18 depositional episodes defines patterns of shifting entry points of continental fluvial systems and quantifies the total volume of sediment supplied during each episode. Eight fluvio-deltaic depocenters, named for geographic similarities to entry points and drainage basins of modern rivers, are present. From southwest to northeast, they are the Rio Bravo, Rio Grande, Guadalupe, Colorado, Houston-Brazos, Red, Mississippi, and Tennessee axes. Sediment volume was calculated from hand-contoured unit thickness maps compiled from basin-wide well and seismic control. Using a GIS algorithm to sum volumes within polygons bounding interpreted North American river contribution, the total extant volume was then calculated. General compaction factors were used to convert modern volume to quantitative approximations of total grain volume. Grain volume rate of supply for each depositional episode was then calculated. Values vary by more than an order of magnitude. Supply rate has commonly varied by two-fold or more between successive depositional episodes. Sediment supply is a significant, independent variable in development of stratigraphic sequences within the Gulf basin. Paleogeographic maps of the continental interior for eleven Cenozoic time intervals display the evolving and complex interplay of intracontinental tectonism, climate change, and drainage basin evolution. Five tectono-climatic eras are differentiated: Paleocene late Laramide era; early to middle Eocene terminal Laramide era; middle Cenozoic (Late Eocene—Early Miocene) dry, volcanogenic era; middle Neogene (Middle—Late Miocene) arid, extensional era; and late Neogene (Plio—Pleistocene) monsoonal, epeirogenic uplift era. Sediment supply to the GOM reflects the interplay of (1

Hydrologic Sub-basins of Greenland, Version 1

Data.gov (United States)

National Aeronautics and Space Administration — The Hydrologic Sub-basins of Greenland data set contains Geographic Information System (GIS) polygon shapefiles that include 293 hydrologic sub-basins of the...

The Members of the Agency

International Nuclear Information System (INIS)

2001-01-01

The new Members since the last list of Member States was issued (INFCIRC/2/Rev.54) are the Republic of Tajikistan, which deposited the instrument of acceptance of the Statute on 10 September 2001 and the Federal Republic of Yugoslavia, which deposited the instrument of acceptance of the Statute on 31 October 2001. The Attachment hereto shows the dates on which the present 133 Member States became Members. It also shows the States whose applications for membership of the Agency have been approved by the General Conference, but which have not yet deposited an instrument of acceptance of the Statute

The members of the Agency

International Nuclear Information System (INIS)

1996-01-01

The document lists the 124 Member States of the Agency as of 1 September 1996. The new Member since the last issue of the list (INFCIRC/2/Rev.47) is Georgia. In an attachment are given the dates on which the 124 Member States became Members, the State (Latvia) whose application for membership of the Agency has been approved by the General Conference but which has not yet deposited an instrument of acceptance of the Statute and the State (Republic of Moldova) whose application for membership has been recommended by the Board of Governors for approval by the General Conference

The members of the Agency

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-09-10

The document lists the 124 Member States of the Agency as of 1 September 1996. The new Member since the last issue of the list (INFCIRC/2/Rev.47) is Georgia. In an attachment are given the dates on which the 124 Member States became Members, the State (Latvia) whose application for membership of the Agency has been approved by the General Conference but which has not yet deposited an instrument of acceptance of the Statute and the State (Republic of Moldova) whose application for membership has been recommended by the Board of Governors for approval by the General Conference.

Hydrological Cycle in the Heihe River Basin and Its Implication for Water Resource Management in Endorheic Basins

Science.gov (United States)

Li, Xin; Cheng, Guodong; Ge, Yingchun; Li, Hongyi; Han, Feng; Hu, Xiaoli; Tian, Wei; Tian, Yong; Pan, Xiaoduo; Nian, Yanyun; Zhang, Yanlin; Ran, Youhua; Zheng, Yi; Gao, Bing; Yang, Dawen; Zheng, Chunmiao; Wang, Xusheng; Liu, Shaomin; Cai, Ximing

2018-01-01

Endorheic basins around the world are suffering from water and ecosystem crisis. To pursue sustainable development, quantifying the hydrological cycle is fundamentally important. However, knowledge gaps exist in how climate change and human activities influence the hydrological cycle in endorheic basins. We used an integrated ecohydrological model, in combination with systematic observations, to analyze the hydrological cycle in the Heihe River Basin, a typical endorheic basin in arid region of China. The water budget was closed for different landscapes, river channel sections, and irrigation districts of the basin from 2001 to 2012. The results showed that climate warming, which has led to greater precipitation, snowmelt, glacier melt, and runoff, is a favorable factor in alleviating water scarcity. Human activities, including ecological water diversion, cropland expansion, and groundwater overexploitation, have both positive and negative effects. The natural oasis ecosystem has been restored considerably, but the overuse of water in midstream and the use of environmental flow for agriculture in downstream have exacerbated the water stress, resulting in unfavorable changes in surface-ground water interactions and raising concerns regarding how to fairly allocate water resources. Our results suggest that the water resource management in the region should be adjusted to adapt to a changing hydrological cycle, cropland area must be reduced, and the abstraction of groundwater must be controlled. To foster long-term benefits, water conflicts should be handled from a broad socioeconomic perspective. The findings can provide useful information on endorheic basins to policy makers and stakeholders around the world.

Recharge and Groundwater Flow Within an Intracratonic Basin, Midwestern United States.

Science.gov (United States)

Panno, Samuel V; Askari, Zohreh; Kelly, Walton R; Parris, Thomas M; Hackley, Keith C

2018-01-01

The conservative nature of chloride (Cl - ) in groundwater and the abundance of geochemical data from various sources (both published and unpublished) provided a means of developing, for the first time, a representation of the hydrogeology of the Illinois Basin on a basin-wide scale. The creation of Cl - isocons superimposed on plan view maps of selected formations and on cross sections across the Illinois Basin yielded a conceptual model on a basin-wide scale of recharge into, groundwater flow within and through the Illinois Basin. The maps and cross sections reveal the infiltration and movement of freshwater into the basin and dilution of brines within various geologic strata occurring at basin margins and along geologic structures. Cross-formational movement of brines is also seen in the northern part of the basin. The maps and cross sections also show barriers to groundwater movement created by aquitards resulting in areas of apparent isolation/stagnation of concentrated brines within the basin. The distribution of Cl - within the Illinois Basin suggests that the current chemical composition of groundwater and distribution of brines within the basin is dependent on five parameters: (1) presence of bedrock exposures along basin margins; (2) permeability of geologic strata and their distribution relative to one another; (3) presence or absence of major geologic structures; (4) intersection of major waterways with geologic structures, basin margins, and permeable bedrock exposures; and (5) isolation of brines within the basin due to aquitards, inhomogeneous permeability, and, in the case of the deepest part of the basin, brine density effects. © 2017, National Ground Water Association.

Members of the LHC Resources Review Boards

CERN Multimedia

Maximilien Brice

2002-01-01

Photo 01: Members of the LHCRRB visiting Point 2, hosting the ALICE experiment From l. to r. : W. Korda, Head of the VIP Office; P. Rimmer, CERN public relations, J. Seed, Member of the LHCRRB, J.-P. Revol, ALICE CERN Team Leader; J. Bartke, Member of the LHCRRB; F. Suransky, Member of the LHCRRB; J. Schukraft, Spokesperson, ALICE experiment and S. Molinari, VIP Office. Photo 02: Members of the LHC Resources Review Boards visiting the ALICE magnet at Point 2. L. to. r.: O. Dines-Hansen, H. Boggild, S. Irgens-Jensens, H.A. Gustafsson Photo 03: Members of the LHCRRB visiting Point 2, hosting the ALICE experiment From l. t to r.: J.Richter, Member of the LHCRRB; H. Gutbrod, Deputy Spokesperson, ALICE experiment; G. Paic, ALICE experiment; D. Muller, Member of the LHCRRB; P. Brau-Munzinger, ALICE experiment; R. Santo, Member of the LHCRRB, A. Van Rijn, Member of the LHCRRB; J. Engelen, Member of the LHCRRB.