Thermodynamic Model of Uranium and Arsenic Accumulation in Saline Lakes

正1 Introduction The attractiveness of Shaazgai-Nuur Soda Lake(pH9.2-9.4)as an alternative metal source is explained by the high concentration of dissolved uranium(~1 mg/l)due to the location of water drainage territory within the Tsagan-     

Uranium in Saline Lakes of Mongolia and Adjacent Areas

正1 Introduction Increasing demand for uranium raw materials for the nuclear industry has stimulated interest in non-traditional sources,including hydromineral ones[Qin,2009].Those are saline lakes located in the uranium ore districts.Accumulation of uranium in such lakes results from the leaching of uranium from the rocks by surface and ground     

New data on stratigraphy (palynomorphs,ostracods, paleomagnetism) of Cenozoic continental deposits of the Ishim plain,Western Siberia

New micropaleontological and paleomagnetic data were obtained by studying core samples of Cenozoic continental deposits from two boreholes drilled in the south of Tyumen oblast (Western Siberia). Palynological assemblages in deposits of the Tavda (upper part), Novomikhailovka, Turtas, Abrosimovka, Tobolsk, Smirnovka, and Suzgun formations were described. Deposits of these formations are enriched in spore-pollen assemblages, which can be correlated with assemblages of regional palynozones of the West Siberian Plain. Ostracods were described in Quaternary deposits. On the basis of biostratigraphic and paleomagnetic data, the Late Eocene (Priabonian)–Holocene age of deposits was substantiated. For the first time, beds with dinocysts of genus Pseudokomewuia were identified in deposits of the Turtas Formation (Upper Oligocene) of the Ishim lithofacial area. In total, nine regional magnetozones were distinguished in the paleomagnetic section. On the basis of palynological and paleomagnetic data, sections of two boreholes were correlated, and hiatuses in sedimentation were revealed. A large hiatus is at the Eocene-Oligocene boundary (Western Siberia): the Lower Oligocene Atlym Horizon and Miocene–Pliocene and Eopleistocene sediments are missing. The Oligocene interval of the section is represented in a reduced volume.     

Main phytostratigraphic boundaries in the Jurassic deposits of Western Siberia

The study of the large collections of plant remains gained from cores of numerous boreholes drilled in Western Siberia made it possible to determine the taxonomic composition of the Jurassic flora of this region, the stages of its evolution, and the sequence of floral assemblages, which characterize the regional stratigraphic horizons indirectly correlated via series of parallel faunal, microfaunal, spore and pollen zonal scales with a general stratigraphic scale. The compositions of floral assemblages was established in the Hettangian-lower part of the upper Pliensbachian, upper part of the upper Pliensbachian, lower Toarcian, upper Toarcian, Aalenian, Bajocian, Bathonian, and Callovian-Oxfordian sediments. Criteria were elaborated to substantiate the Triassic-Jurassic and Lower-Middle Jurassic boundaries. Lithologically and biostrati-graphically, the Middle-Upper Jurassic boundary is poorly expressed.     

Chemical Composition of Some Saline Lakes in the Tuva Region(Russia)

正1 Introduction Salt lakes are very interesting natural objects which can be found in different places in the world.Russia is not an exception.Climate conditions are various in Russia,but the climate is not very hot.In Russia there are a lot of places where salt lakes are spread.One of them is the Tuva region where lakes with different compositions are     

我国西北地区盐湖中的铀234U/238U比值示踪研究

内蒙古二连盆地、鄂尔多斯盆地典型含铀碳酸型盐湖水、岩两相234U/238U综合分析表明,碳酸型盐湖铀来源于大气降水和潜水对盐湖盆地周围中生代到现代富铀沉积物的溶滤、浸出,具有快速、近源物质来源特点。盐湖卤水和对应沉积物234U/238U值一般为0.8～1.2,湖卤水和潜卤水（晶间卤水）-岩两相中的铀处于沉积平衡状态。早白垩世～上新世含膏盐地层对比研究证实了富铀岩层234U/238U值随铀含量增大而减小,并趋近于1。室内盐湖水蒸发模拟实验发现残余卤水、沉积物234U/238U具有随蒸发程度增大逐渐减小的变化特征。盐湖现代沉积物物相研究发现铀主要以碳酸铀酰和吸附形式赋存在富含有机物和碎屑成分的含盐粘土沉积中,铀在盐类晶体中含量极少,仅存在于封闭水和结晶水中。卤水和沉积物ARu值是盐湖铀源及铀含量水平的指示标志之一。     

The Saline Lakes of the McMurdo Dry Valleys, Antarctica

The McMurdo Dry Valleys of Antarctica are among a rare group of ice-free regions lying along the coast of an otherwise ice-burdened continent. For Antarctica, these are highly atypical regions of exposed rock and barren soils. Within their 4,000 km² expanse, the valleys contain a number of permanently ice-covered, closed-basin lakes, which range from freshwater to highly saline environments. This paper examines the physical structure, geochemistry, nutrient and trace metal dynamics, biology, and hydrologic history of saline Lake Bonney (both east and west lobes), Fryxell, Vanda, and Joyce and provides an update to recently published volumes on these pristine systems.     

The geochemical patterns of rocks of the Bazhenov and Abalak formations (Western Siberia)

The composition of rocks of the Bazhenov and Abalak formations in Western Siberia is described. Correlations of the concentrations of the major and minor components in rocks with the concentrations of minor elements and organic material are shown. Study of the concentration of minor elements allows us to determine the conditions of sedimentation: redox potential, hydrogen sulfide contamination, and the source of sedimentary material. The results show that rocks of the Bazhenov Formation were formed under the conditions of low fluxes of clastic material, a reduced environment, and a periodically occurring hydrogen sulfide mode.     

我国西北地区盐湖中234U/238U比值与铀关系研究——以内蒙古地区碳酸盐型盐湖为例

内蒙古二连盆地、鄂尔多斯盆地典型含铀碳酸型盐湖水、岩两相2344U/23898U综合分析表明,该类盐湖铀来源于降水和潜水对盐湖盆地周围中生代以来富铀沉积物的溶滤、浸出,具有快速、近源物质来源特点.盐湖卤水和对应沉积物234 U/238U比值一般为0.8～1.2,盐湖卤水和潜卤水(晶间卤水)岩两相中的铀处于沉积平衡状态.含铀盐湖水、沉积物的234 U/238U比值随其铀含量增大而减小,并趋近于1,富铀盐湖水及沉积物234U/238U比值介于0.9～1.5之间.室内盐湖水蒸发模拟实验发现,残余卤水、沉积物234U/238U、铀总量具有随蒸发程度增大逐渐减小的变化特征.铀主要以碳酸铀酰络合物和吸附形式赋存在富含有机物和碎屑成分的含盐粘土沉积中.卤水和沉积物234 U/238U比值是盐湖铀源及铀含量水平的有效指示标志之一.     

Sedimentation models for the Jurassic stratum in the Potanai oilfield (Western Siberia)

The sedimentation models for the upper part of the Tyumen Formation (the J_2?C3 productive layers) and the Abalak Formation (J ₁ ² and J ₁ ¹ ) were constructed on the basis of data from lithological studies of Jurassic stratum cores (the Potanai oilfield in the northeast Shaim megaswell). The models show that the sedimentation environment sequentially changed from the continental to the deltaic, lagoonal, and shelf types through the Middle and Late Jurassic.     

Trap magmatism and mobilization of hydrocarbon fluids (Western Siberia)

Drill core material from the superdeep SG-6 and SG-7 wells (Koltogor-Urengoi Graben) has been examined. It has been established that the temperature conditions of alteration of sediments were non-linear and discontinuous. The basalts underlying these sediments are metamorphosed and metasomatically altered under the influence of high-temperature fluids associated with a superplume. The tuffs under the basalts have a phreatic origin. It is assumed that the intrusion of basaltic sills into the coal-bearing Permo-Carboniferous rock mass beneath the tuffs caused thermolysis of coals and the generation of hydrocarbon gases of a methane composition.     

Main minerals of abnormally high-grade ores of the Tomtor deposit (Arctic Siberia)

The Tomtor massif of Paleozoic ultramafic alkaline rocks and carbonatites is located in the northern part of the Sakha Republic (Yakutia). The massif (its total area is ~ 250 km²) is ~ 20 km in diameter, with a rounded shape and a concentrically zoned structure. The core of the massif consists of carbonatites surrounded by a discontinuous ring of ultramafic rocks and foidolites. The outer part is composed of alkali and nepheline syenites. All rocks are weathered and covered with eluvium, which is the thickest after carbonatites enriched in phosphates and REE. The weathering profile consists of four layers, from the top: kaolinite-crandallite, siderite, goethite, and francolite. The highest-grade ores are observed in the bedded deposit which fills depressions in “sagging” eluvium. The ores are laminated and cryptogranular, with high Nb, Y, Sc, and REE contents (on average, 4.5% Nb₂O₅, 7-10% REE₂O₃, 0.75% Y₂O₃, and 0.06% Sc₂O₃). The highest-grade ores are natural Nb and REE concentrates. The total REE content in some layers is > 10%. The morphologic features of the highest-grade phosphate ores from the northern part of the Burannyi site were studied. The ore-forming minerals belong to the pyrochlore group, crandallite group (goyazite), and monazite-Ce. The pyrochlore group minerals occur mainly as crystals that were completely replaced by barium-strontium pyrochlore and/or plumbopyrochlore but retained the original faces; also, they occur as numerous conchoidal fragments. The grains of the pyrochlore group minerals sometimes have a zonal structure, with an unaltered pyrochlore core and a reaction rim. Goyazite occurs predominantly as colloform grains. According to SEM and TEM data, monazite occurs in the ores as ~ 50 nm particles, which cover the outer part of halloysite tubes (800–3000 nm long and 300 nm in diameter) as a dense layer and make up peculiar biomorphic aggregates. The mineralogical data, the occurrence of biomorphic aggregates, and the close association of organic remains with ore minerals suggest that the high-grade ores of the Tomtor deposit, including the Burannyi site, resulted from a hydrothermal-sedimentary process with a presumably important role of bioaccumulation of REE phosphates.     

阿拉善高原盐湖水化学特征的主成分分析研究

运用数理统计的主成分分析法对阿拉善高原腾格里沙漠地区和巴丹吉林沙漠地区的21个盐湖、八种水化学特征变量进行研究,获得四个可以揭示水化学特征的主成分及相应的数学模型,进一步得出各盐湖在四个新的主成分变量上的得分值,从而解释八种水化学成分变量与盐湖类型之间的相关信息。     

Formation Conditions and Main Controlling Factors of Uranium in Marine Source Rocks

The research of petroleum exploration demonstrates that source rocks, developed in petroleum-bearing sedimentary basins worldwide, are accompanied by uranium to different degrees.As a special element with catalytic, oxidative and radioactive features, uranium may play important roles in the source rock formation and hydrocarbon generation. In this paper, we systematically discussed the formation conditions and main controlling factors of uranium in marine source rocks based on the comprehensive analysis of uranium contents in the worldwide source rocks and the interactions of uranium with minerals, organic materials and microbes. The results indicated that oxidative degrees of ancient atmosphere and palaeo-ocean were governing factors of uranium enrichment in source rocks. Oxidative weathering and hydrothermal solution might be the two main sources of marine sedimentary uranium. In addition, iron-bearing minerals, phosphate minerals, clay minerals, organic materials, and microbes were of great significance in promoting the transformation of the uranium valence states. They could also act as carriers to absorb or combine uranium, resulting in the enrichment of uranium in sediments. Therefore, the enrichment of uranium might be an inevitable result of source rocks formation.     

塔里木盆地塔中I号断裂带西缘奥陶系油气成藏与主控因素研究

塔中低凸起是塔里木盆地油气资源最丰富的地区之一,而塔中I号断裂带西缘也在多个层系中见到了不同程度的油气显示,并在上奥陶统良里塔格组获得了高产工业油气流,在下奥陶统鹰山组获得了低产油气流.本文通过油源对比、油气水物性对比、包裹体均一温度分析等方法并结合前人的研究成果,探讨了塔中I号断裂带西缘塔中86井区-塔中45井区奥陶系的油气成藏过程,认为该区奥陶系有过三期油气充注,即晚加里东期、晚海西期和燕山期-喜马拉雅期.晚加里东期的油气来自于寒武系-下奥陶统烃源岩,晚海西期的油气来自于中-上奥陶统烃源岩,两期油气均自塔中88井沿碳酸盐岩岩溶储层侧向运移而来;燕山期-喜马拉雅期主要以天然气为主,成因复杂.另外,认为该区油气富集的主控因素主要有3点:多源多期油气充注、优质的碳酸盐岩岩溶储层及各种成藏要素的优质配置.     

Preliminary Analysis on the Main Control Factors of Shale Gas Accumulation

<正>*Shale gas has rich resources in China where many basins possess the advantage reservoir forming conditions of shale gas.Sichuan Basin,Ordos Basin,Bohai Bay Basin and Jianghan Basin,for example.On the basis of combinational analysis,shale gas accumulation is controlled by many factors,for instance organic matter abundance,type and maturity,reservoir physical property,     

The Formation of the Qarhan Saline Lakes as Viewed in the Light of Neotectonic Movement

Investigations on stratigraphy, geomorphology and neotectonic movement in the Eastern Kunlun Moun-tains show that there existed a series of ancient lakes, including some saline lakes. in the studied region about30,000 years ago, They were distributed south of the middle Kunlun fault. from the middle-upper reaches of thepresent Narin Gol River in the west to the Alag Lake-Tosou Lake in the east. Of these the ancient Narin GolLake and Kunlun Lake were mainly recharged by the hot water related to valcanos. so the B, Li and K con-tents are relatively high. The neotectonic movement that commenced at 30.000 a B.P. caused the river system in the EasternKunlun Mountains to invade southwards. as a result the ancient lake water was captured to recharge theQarhan area. Therefore, the hot springs related to recent volcanism and faulting on the southern bank of theupper reaches of the Narin Gol River became an important source of saline materials for the Qarhan Lake.     

Isotopic Evolution of Saline Lakes in the Low-Latitude and Polar Regions

Isotopic fractionations associated with two primary processes (evaporation and freezing of water) are discussed, which are responsible for the formation and evolution of saline lakes in deserts from both low-latitude and the Polar regions. In an evaporative system, atmospheric parameters (humidity and isotopic composition of water vapor) have strong influence on the isotopic behavior of saline lakes, and in a freezing system, salinity build-up largely controls the extent of freezing and associated isotope fractionation. In both systems, salinity has a direct impact on the isotopic evolution of saline lakes. It is proposed that a steady-state “terminal lake” model with short-term hydrologic and environmental perturbations can serve as a useful framework for investigating both evaporative and freezing processes of perennial saline lakes. Through re-assessment of own work and literature data for saline lakes, it was demonstrated that effective uses of the isotope activity compositions of brines and salinity-chemistry data could reveal dynamic changes and evolution in the isotopic compositions of saline lakes in response to hydrologic and environmental changes. The residence time of isotopic water molecules in lakes determines the nature of responses in the isotopic compositions following perturbations in the water and isotope balances (e.g., dilution by inflow, water deficit by increased evaporation, and/or reduction in inflow). The isotopic profiles of some saline lakes from the Polar regions show that they switched the two contrasting modes of operation between evaporative and freezing systems, in response to climate and hydrological changes in the past.