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    14 June 2016, Volume 30 Issue 3
    Engineering Geology and Environmental Geology
    Geochemical Characteristics of Trace Elements of Chencai Group in  Jiangshan–Shaoxing Fault Zone of Zhejiang and Its Relation to Mineralization
    2016, 30(3):  493-502. 
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    One of important ore-bearing strata in southeastern Zhejiang Province is Chencai Group that is exposed in southeastern Jiangshan-Shaoxing fault zone. In this stratum, many large and medium-sized polymetallic deposits such as gold, silver, copper have been found. The source of ore-forming materials has long been a hotspot among the research of genesis of these deposits, therefore, the geochemical characteristics of metamorphic rocks in Chencai Group have also received extensive attention. This paper takes the newly discovered Zhoujiawu copper deposit in Zhuji area as the research object, then conducts a systematic analysis of trace elements and rare earth elements of metamorphic rocks and ores. The results show that the average contents of ore-forming elements and accompanying elements such as Au, Ag, Cu, Zn, S, Mo in Chencai Group are significantly higher than crustal abundance, obviously Chencai Group has a advantageous material condition for mineralization. The consistency and inheritance of REE compositions of skarn and ores suggest that in Zhoujiawu copper deposit, the elemental enrichment and even mineralization may be closely related to activation and migration of elements in metamorphic rocks of Chencai Group. In summary, this research can provide direct evidence for the understanding of the role of Chencai Group for mineralization.

    The Rock Geochemical Exploration and Metallogenic Prediction in the Layikeleke Porphyry Copper Deposit,Eastern Junggar,Xinjiang
    2016, 30(3):  503-513. 
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    The Layikeleke copper deposit located in the south central part of Qiongheba ore concentration area in eastern Junggar of Xinjiang has good prospecting potential. Therefore, the Layikeleke deposit is worthy to be further researched. Through systematic study of 15 kinds of trace elements and 9 major elements in the deposit, this study summed up the characteristics of element enrichment and depletion, and the regularity of the contents of these elements changing with main ore-forming elements of Cu to select index elements. Taking No.K0, K1 prospecting sections as examples, the characteristics and regularities of mass transfer in tonalite and tuff are discussed. The results show that the positive anomalies of enrichment elements including Cu, Ag, Mo, S, Se are well corresponded with the copper ore bodies, the negative anomalies of depleted elements including Ba, Sr, Rb, K2O in tuff and Ba, MgO, Na2O, CaO in tonalite cover the prospecting section. This article discusses emphatically the formation mechanism of negative anomalies of MgO, Na2O, CaO in tonalite. Using the theory of multidimensional anomaly system as the guide, we analyzed the spatial distribution characteristics of metallogenic elements and geochemical characteristics and difference of the area without mineralization. Comprehensive utilization of different attributes of the anomalies can indicate the direction of ore-prospecting.

    Tracing the Stream Sediment of the Ganjiang River(Nanchang Section):Constraint from the Detrital Zircon U-Pb Isotope Evidence
    2016, 30(3):  514-527. 
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    The Ganjiang River is the biggest river in Jiangxi Province, which is also one of eight major tributaries of the Yangtze River. In order to investigate the material source of stream sediment in the Ganjiang River, the U-Pb age of detrital zircons from the Ganjiang River (Nanchang Section) were carried out by the LA-ICP-MS analysis technique. One hundred and twenty three spots are effective among the 140 analytical spots. The data suggest that zircons are mainly composed of 7 age stages, including 134-197 Ma, 221-290 Ma, 386-484 Ma, 520-625 Ma, 727-895 Ma, 980-1,110 Ma and 2,502-2,861 Ma, respectively, corresponding to the known tectonic-magmatic thermal events, i.e., Yanshanian Movement, Indosinian-Hercynian Movement, Caledonian Movement, Jinning Movement, Lüliang Movement. The Th/U ratios of most zircons with distinct magmatic zoning are more than 0.4, indicating that they are of magmatic origin. The result reveals that the zircons of 134-197 Ma mainly come from Southern and Central Jiangxi, Western Fujian and Northern Guangdong area. The Indosinian zircons of 221-290 Ma mainly stem from Southern Jiangxi and Hercynian zircons from Central Jiangxi and Jiuling area. The zircons of 386-484 Ma mainly come from Southern and Central Jiangxi and some are from Northwestern Jiangxi Province. The zircons of 520-625 Ma could be judged that they come from Southern Jiangxi. The zircons of 727-895 Ma are mainly from Jiuling area. The zircons of 980-1,100 Ma and 2,502-2,861 Ma mainly come from Southern Jiangxi and Northern Guangdong in Cathaysia Block. Therefore, the main material resource of the Ganjiang River could be effectively constrained by the U-Pb age of the detrital zircon from stream sediment.

    Geochronology and Geochemistry of the Wurinitu Granites in Inner Mongolia and Their Geological Implications
    2016, 30(3):  528-540. 
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    The Wurinitu granitoid pluton, located in the northwestern of the Wurinitu Village, Chaganaobao town, Sunidzuoqi County, Inner Mongolia, is a concealed rock mass and mainly composed of fine to middle-fine grained granite and adamellite. Petrography and geochemical characteristics indicate that it belongs to high-K calc-alkaline series. Its SiO2 contents range from 74.85% to 78.10%, while K2O/Na2O ratios and A/CNK values vary from 1.45 to 3.08 and 1.00 to 1.21, supposed to a suite of peraluminous rock. Rb, Th and U elements are enriched in the intrusion while Ba, Nb, Sr, P and Ti depleted. REEs show characteristics of obvious negative Eu anomalies(δEu= 0.22-0.39)and right-dipping“V”patterns with LREE enrichment. On the basis of LA-ICP-MS U-Pb chronological study of zircons, the U-Pb dating results from the granites are 139 Ma implying that they formed in Early Cretaceous, Late Yanshanian stage. Chemically, the granitoids belong to A-type, implying that they formed under an extensional tectonic setting. The source compositions of the granites are different, and they are mainly derived from clay-rich pelite with a spot of arenite, resulted from metamorphism.

    Geochemistry of Cretaceous-Palaeocene Detrital Rocks in Simao Basin,  Yunnan Province and Its Geological Significances 
    2016, 30(3):  541-554. 
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    The Cretaceous-Palaeocene strata in the Simao Basin consists of the Mangang Formation (K1m), the Pashahe Formation (K1p), the Mengyejing Formation (K2me) and the Denghei Formation (E1d), which are primarily composed of sandstone and mudstone. Based on the geochemical research into detrital rocks of 19 pieces of samples from ErguanzhaiHepingzhai-Bashahedaoban section and 17 pieces of samples from drilling hole SHK4 in Mengyejing deposit of Jiangcheng, three conclusions have been drawn which are presented as follows. Firstly, in theses samples, δCe vs. δEu, δCe vs. ∑REE, CIA vs. Th/U, CIA vs. Th/Sc show no correlation, which imply that the Cretaceous-Palaeocene clastic rocks are mainly controlled by source region rather than chemical weathering and oxidationreduction conditions. Secondly, the distribution patterns of rare earth elements are basically the same; LREE/HREE ratios are high; Eu negative anomalies are evident, indicating the same source region of the Cretaceous-Palaeocene sediments with little mantle material adding. The rocks are mainly pro-granite felsic, and the parent rock debris comes predominately from the upper crust which is in accordance with the features displayed by the Hf-La/Th,La/Sc-Co/Th,REE-La/Yb,Hf-Co-Th discrimination diagrams. Thirdly, during the deposition of Mengyejing and Denghei Formations, a sudden rise of CaO content, Gd content, ICV, (Gd/Yb)N  ratio demonstrates that the provenance area is in an rapid uplift and erosion stage. The research provides a geochemical basis for the provenance of Cretaceous-Palaeocene strata in the Simao Basin.

    Hydrothermal Alteration and Its Geochemical Characteristics of Lijialing Deposit in Xiangshan Uranium Ore Deposit
    2016, 30(3):  555-566. 
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    Lijialing uranium deposit is a new uranium deposit of discovered in western Xiangshan in recent years. Hydrothermal alteration develops strongly and obvious alteration zoning phenomenon exists in this deposit. Based on detailed field and indoor petrography observation on the drilled well samples, this paper divided uranium mineralization period into center zone, near-ore alteration zone, near-ore alteration zone and far-ore alteration zone, of which the hydrothermal alteration intensity decreases gradually. Standardized Isocon graphic method shows that in the hydrothermal alteration zone, CaO, FeO, Fe2O3, Na2O contents increase significantly, with accordance to the development of hematite, albitization and carbonatization facies. K2O content decreases obviously, which is caused by that albite replace potash feldspar and then the K element is migrated from potash feldspar; while MnO and MgO display a characteristic of inversely proportional relationship, which shows that hydrothermal alteration metasomatic process is not only a kind of diffusion infiltration metasomatism, but also a kind of element migration pattern with convective equilibrium.The content changes of the trace elements such as Th, Y, Zr and Hf are consistent with those of uranium, indicating that those elements can be used for prospecting uranium mineralization. HREE contents are closely relative to the uranium mineralization. With enhancement of the alteration degree, the HREE contents increase more and more, which indicates that the oreforming fluid is rich in HREE, and is deeply derived.

    Fluid Inclusions of Layimu Basalt Native Copper Deposit in the Sichuan-Yunnan-Guizhou Border Area, China
    2016, 30(3):  567-576. 
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    A large area of native copper mineralization, which formed in the southwestern margin of the Yangtze platform, is an important part of the Emei mantle plume metallogenic system. We studied the fluid inclusions of Layimu basalt native copper deposit in the Zhaojue County, Sichuan Province. According to the determination of inclusions composition in quartz and calcite, the ore forming fluid is divided into two stages as follows. Early stage ore-forming fluids have mixed characteristics of basinal saline fluid and organic fluid with medium-low temperature and high salinity. The fluid is composed of water, a small amount of methane, hydrocarbon and asphalt. Liquid hydrocarbon is an aromatic hydrocarbon, with strong fluorescence. The homogenization temperature range of early-stage fluid inclusions is 140-306 ℃, with three salinity content values of 3%-10%,11%-14%,21%-24%, and average salinity content of 8.6%. The late-stage fluids are of low temperature and low salinity characteristics, and the homogenization temperature range of these fluid inclusions is 80-190 ℃, with salinity content  of 0.2%-8%, and average salinity content of 4.8%. These data suggest that the late-stage fluid is formed by the atmospheric precipitation infiltration and water-rock reaction. The features of fluid inclusion of Layimu basalt native copper deposit are consonant with those of the Zhaotong area, northeast of Yunnan. The main mechanism of the enriched precipitation of native copper mineralization in this area is as the following: reaction of inorganic and organic substances, mixture of mantle fluids and other different types of fluid, lackness of sulfur conditions or organic reduction.

    Prospecting Model Based on Ground Hyperspectral Remote Sensing Data of Hongshan Cu-Au Ore Deposit in Xinjiang
    2016, 30(3):  577-586. 
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    Using FieldSpec Pro FR ground spectroscopy of American ASD Company, the authors carried out ground spectrum measurement for different geological bodies such as dacite,altered dacite,granite,granodiorite,rhyolite porphyry, schistosity belt and ore body respectively in the Hongshan Cu-Au deposit.The spectrum curves of geological bodies were achieved; and then the characteristics of absorption peak of spectrum and altered minerals were generally analyzed. According to the analysis results of microscopic identification and X-ray diffraction, this paper summarized the hyperspectral distribution characteristics of altered minerals and the mineral assemblage which are distributed in ore body, mineralized body, wall rock near ore body, altered wall rock and non-altered wall rock in the Hongshan Cu ore deposit. Based on the characteristics of mineral geology and ground wall rock alteration, the hyperspectral map of altered mineral assemblage formed and the prospecting model based on ground hyperspectral remote sensing data were constructed. The research provides hyperspectral data and typical deposit model for the further aerial survey, information extraction of altered minerals, and prediction for ore deposits.

    Application of 3-D Inversion Method of AMT Data on the Detection of Hidden  Faults in the Near-surface Structure:An Example from Tan-Lu Fault Zone
    2016, 30(3):  587-596. 
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    In this paper the AMT method was applied to study the concealed faults of Tan-Lu Fault zone in Suqian, Jiangsu Province. Three AMT profiles had been deployed which included 61 AMT sites and the electrical strike and its dimension were analyzed with these data. By conducting traditional 2-D and advanced 3-D inversion methods, the reliable underground geoelectric models were obtained. The geoelectric strike direction of the sites near the fault derived from GB decomposition is about to N60°E from shallow to deep, which is inferred to be the strike of main fault or branch fault, and is slightly different from that derived from the shallow geological mapping (~N20°E).Then based on the phase tensor analysis result, the dimension data near the fault show 3-D features in some depths. The 3-D inversion method can provide more reliable models of the concealed fault and comprehensively reflect the information of fault tendency, extending depth and other features, so 3-D inversion method is more reliable than the traditional 2-D inversion method.In addition, the location of the fault obtained from the 3-D inversion model matches well with that inferred from radioactive element detection. In conclusion, the geoelectric strike and dimension analysis for electromagnetic data are necessary in the exploration of concealed faults, and the 3-D inversion method can get more reliable resistivity models for concealed faults than the 2-D inversion method.

    Two-dimension Joint Inversion of Magnetotelluric and Seismic Reflection Travel Time Data
    2016, 30(3):  597-605. 
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    Because of the problem of multiple solutions for geophysical inversion, how to reduce the multiple solutions to improve the reliability and accuracy of the results of geophysical inversion is a hot geophysical research topic today. To reduce the multiple solutions of magnetotelluric and seismic data inversion, this study develops a 2-D joint inversion algorithm of magnetotelluric data and seismic data on the base of cross-gradient theory which is proposed by Gallardo and Meju, and the theoretical geoelectric model and velocity model are designed for single inversion and joint inversion, then the 2-D joint inversion algorithm of magnetotelluric and seismic data is verified to be correct and valid. The inversion results show that the above inversion algorithm with cross-gradient constraints can cause the resistivity model and velocity model constrain each other so that the joint inversion result is closer to the reality than the single inversion result. Therefore, the joint inversion is more reliable, which can reduce the multiple solution of geophysical inversion.

    Magnetic Properties of Tree Leaves in Different Environments and the Indication for Atmospheric Environment Pollution
    2016, 30(3):  606-613. 
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    In order to study the indicating effect of tree leaves’ magnetic properties on atmospheric environment pollution, magnetic parameters were measured on the poplar tree leaves collected from the downtown of Fengyang County, Anhui Province, cement plant and quartz sand plant of Fengyang, and ginkgo tree leaves and phoenix tree leaves grown in the downtown of Fengyang County. Results showed that the main magnetic mineral in tree leaves was magnetite, and its particle was coarse; the magnetic mineral content of poplar tree leaves in different environment was not the same, ranking from high to low as cement plant, Fengyang County and quartz sand plant, which indicated that the degree of atmospheric environment pollution in cement plant was more serious than than in the other two sites. Further analysis suggested the magnetic mineral contents of poplar tree leaves, ginkgo tree leaves and phoenix tree leaves collected from the downtown of Fengyang County differed from one another, and that of ginkgo tree leaves was higher than those of the other two. Thus, using magnetic parameters of tree leaves can monitor the atmospheric environment pollution, while the indication effect of different species leaves exists difference.

    Geochemical Characteristics and Its Significance of Reservoir Bitumen of Longwangmiao Formation in Moxi Area, Sichuan Basin
    2016, 30(3):  614-626. 
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    Based on the information about reservoir bitumen, such as occurrences, elemental composition, carbon isotope, gas chromatogram for saturated hydrocarbons, the characteristics of biomarkers and aromatic hydrocarbon, this paper analyzes the geochemical characteristics, genesis and source of reservoir bitumen from Longwangmiao Formation in Moxi area. The bitumen is primarily characterized by high reflectance (equivalent Ro>2.0%) and low H/C atomic ratios, suggesting that they are residuals generated from oil cracking, belonging to a pyrobitumen. N-alkane in reservoir bitumen distributes integrally with the carbon number ranging from C16 to C31, without obvious trace of biodegradation. Its possible source rock developed in reducing environment and the bitumen mainly derived from aquatic algae and the source rock might be shale. Its carbon isotope value(-33.1‰~-35.4‰) and the biomarker are very comparable to the kerogen’s in the Lower Cambrian source rock, demonstrating that the bitumen came from Qiongzhusi Formation.

    Hydrocarbon Generation Kinetics and the Efficiency of Petroleum Expulsion  of Lacustrine Source Rocks: Taking the Qingshankou Formation in the Songliao Basin as An Example
    2016, 30(3):  627-634. 
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    To evaluate the yields of oil and the potential of tight oil resources of lacustrine source rocks, the characteristics of hydrocarbon generation, kinetic parameters, and the efficiency of petroleum expulsion of lacustrine source rocks in the Songliao Basin were studied in this paper, by using the gold-tube pyrolysis of lacustrine Type-I organic matters and organic geochemical analysis of the Qingshankou Formation source rocks. Quantitative determination of the liquid and gas products from pyrolysis experiments indicate that there is a considerable oil generation potential for the Qingshankou Formation source rock in the Songliao Basin with maximum yields of oil about 600 mg/g·TOC. Kinetic calculation shows that the average activation energy for oil generation from this source rock is 218.5 kJ/mol, wherein, the activation energy for the generation of heavy components is obviously lower than that of light parts. Geological extrapolation based on the kinetic parameters and the thermal history of well YX58, demonstrates that the present generation conversion and amounts of oil for the source rocks of tight oils in this well are 40% to 60% and 240 to 360 mg/g·TOC, respectively. By determination of the residual hydrocarbons, the expulsion amounts and efficiency of oils for this source rocks can be calculated to be 150 to 200 mg/g·TOC and 25% to 33%, respectively. It is shown that tight oil resources are of great potential in the Songliao Basin.

    Application of High-resolution Sequence Stratigraphy to Braided River Facies:Taking the Yanqing Silicified Wood National Geopark Section in Beijing as An Example
    2016, 30(3):  635-642. 
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    Through the observation and measurement on three braided river sedimentary outcrops of Yanqing Silicified Wood National Geopark Section in Beijing, three braided river microfacies of braided channel, floodplain and splay are been identified, and their sedimentary characteristics are analyzed. Two full medium-term cycles and some short cycles that constitute the medium-cycles are divided using the base-level cycles change principle of high-resolution sequence stratigraphy, and the stratigraphic framework is established. The cycle conversion surface identification of the braided river outcrop is summed up as the flooding surface and the sequence boundaries. Flooding surfaces include the wet floodplain shale development segments with a certain thickness and distribution, the splay stacked locations with a larger thickness and the isolated channel layers. Sequence boundaries include the locations  with little or no development of flood plain mudstone, the locations of stacked river channel on the erosion surface and the positions of the river channel that can be correlated and has a big scale in a certain range. The braided channel sand bodies produced in low A/S ratio, are superimposed into a film horizontally and overlaid each other vertically, with good connectivity, big thickness, little mud, good heterogeneity and strong contractility. While the braided channel sand bodies that are produced in high A/S ratio, are isolated and less overlaid, with small thickness, limited range in horizon, high clay contain and poor connectivity. As a result, the high-resolution sequence stratigraphy of braided river facies is initially formed, which can provide the basis for the establishment of high accuracy correlation framework and the recognition and prediction of reservoir in outcrop braided river depositional system.

    Sedimentary Characteristics of Fine-grained Alluvial Fan: A Case Study of the Paleogene Baiyanghe Formation in Laojunmiao Structural Belt, Jiuxi Basin
    2016, 30(3):  643-654. 
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    Based on abundant core, logging and seismic data, this paper mainly analyzed the sedimentary types and characteristics of the Paleogene M reservoir in Laojunmiao structural belt, and further discussed the distribution characteristics, as well as their main controlling factors. The result shows that M reservoir develops fine-grained alluvial fan,which contains upper fan, mid fan and lower fan deposits, with size-decreasing grains in a complete retrograding sedimentary sequence. The deposit displays fan-shape in plane view and convex-shape in cross section. And an incised valley is developed in the root of fan-shaped deposits. The width of individual fan varies from 5 km to 10 km,with the length from 12 km to 15 km and thickness from 15 m to 25 m.The width of incised valley ranges from 2 km to 4 km, with incised depth from 20 m to 25 m.Sandbodies display thinner thickness and wider distribution in the longitudinal direction, which is affected by the landform. The formation of the fine-grained alluvial fan in the study area is controlled by three factors, including geomorphology, source rocks and climate. Open topography at the toe of mountain provides an open landform for the generation of alluvial fan, which, together with the fine-grained clastic sediments from the paleo-weathering crust of Cretaceous mudstone and sandstone, are the main factors controlling the generation of the fine-grained alluvial fan. Hot and dry climate intensifies the weathering process of the source rocks.

    Application of Facies-controlled Property Modeling Technologies To Characterization of Low Permeability Oilfield in the Ordos Basin
    2016, 30(3):  655-662. 
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    The W low permeability oilfield with well 21 block in the Ordos Basin is characterized by ultra-low permeability oil reservoir with strong heterogeneity, and the effect of water flooding is not promising. In order to characterize the reservoir heterogeneity and its through-going characteristics, this paper establishes the structural model, lithofacies model, the sedimentary microfacies model, and the microfacies-controlled property model step by step using facies-controlled modeling technologies with multiple stochastic modeling methods based on the geology investigations, petrographic observations, log analysis, and production performances. The comparison between facies-controlled modeling and non-facies-controlled modeling reveals that facies-controlled property modeling resulted in a more reliable and realistic descriptions of the targeted reservoir heterogeneities. An seamless integration of 3D model established by Petrel and Eclipse simulations gets good application in later research on CO2-EOR numerical simulation. The successful application of the facies-controlled property modeling technologies in the Ordos Basin shows that such approach can characterize the properties of the low permeability reservoir with multi sedimentary mirco-facies and strong heterogeneity, and can describe connectivity and distribution feature of sand, providing a reliable petrophysical property model for optimizing the development strategy of ultra-low permeability reservoirs.

    Shallow Super Heavy Oil Reservoir Accumulation Process and Model in LX Oilfield, Liaodong Bay Depression
    2016, 30(3):  663-671. 
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    In order to investigate the complex accumulation model of super heavy oils in LX oilfield (Minghuazhen and Guantao formations), integrated data including geochemical, petrophysical and fluid inclusion analysis were applied in this study to reconstruct the charge history in Dongying Formation, and to characterize the evolution process of oil properties and therefore densification during the charge period. Based on the combined analysis on both the shallow braided channel reservoir and oil saturation, the accumulation processes and model of super heavy oil in shallow reservoirs were established, the result as follows: (1)The hydrocarbon accumulation in shallow Minghuazhen and Guantao formations is strongly associated with the destroy of deep Dongying  oil reservoirs. The hydrocarbon in Dongying Formation was accumulated during 28 to 25 Ma and thereafter suffered biological degradation. During the oil evolution history, the density was increased firstly and then the viscosity was increased, which reduces the oil properties and decreases the requirement to cap rock sealing capacity. The dynamic evolution processes made it possible that crude oil could accumulate in the Minghuazhen and Guangtao formations which have poor sealing capacity during 5~0 Ma. (2)The vertical cyclicity of the oil saturation and oil properties is ascribed to the vertical stacking pattern of braided channel sandy bodies in Minghuazhen and Guantao formations as well as the fact that crude oil were suffered from biological degradation during the charging time. This is corresponding to the cycles of reservoir lithology. In term of these analysis, we established the hydrocarbon charge models and characterized the vertical distribution of crude oils.

    The Spatial Distribution and Its Formed Mechanism of Fluoride in the Unconfined and Confined Groundwater of Tuoketuo County, Inner Mongolia
    2016, 30(3):  672-679. 
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    Insufficient or excessive intake of fluoride can create health problems for humans. The objective of this study was to understand the occurrence of fluoride in groundwater as well as its spatiotemporal variation and reasons in Tuoketuo County, Hohhot, Inner Mongolia, in view of the factors influencing the sources, migration and enrichment of fluorine. Sixty water samples(30 phreatic and 30 confined sources) were conducted a statistical analysis, water chemistry characteristics analysis, cluster and correlation analysis. The fluoride concentration in water samples varied from 0.40 to 7.20 (2.30±1.80) mg/L and 0.29-12.70(1.67±2.48)mg/L in phreatic and confined water, respectively. An analysis of the hydrogeochemical characteristic of samples indicated that the high fluoride content of groundwater was caused by the alkaline environment with high levels of TDS, HCO-3, Na+, EC and with a Ca2+ deficiency. High F- concentrations were mainly observed in ground-water of HCO3·Cl-Na type. The highest concentration of fluoride (>5 mg/L) in phreatic water was located in the groundwater discharge area because this water was affected by the groundwater flow field. In confined aquifers, the concentration of fluoride was mainly controlled by lithology; a high fluoride content (>1.5 mg/L) was only observed in lacustrine platform zone in confined aquifers in the study area.

    Formation and Evolution of Main Chemical Components of Surface Water and Groundwater in Turpan Basin
    2016, 30(3):  680-687. 
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    Turpan Basin is one of the inland basins in Northwest China, which is rich in major mineral resources (e.g. iron ore). Investigation of the formation and evolution of chemical composition in groundwater and surface water in Turpan Basin is critical to the utilization and protection of groundwater in this region. In this study, inorganic ion tracer method was employed to analyze the relationship between main ions and Cl- or main ions/Cl- and Cl-, and the formation of major chemical composition in surface water and groundwater in Turpan Basin was also investigated. Furthermore, the evolution of chemical composition and the potential source of salt in groundwater in this region was also illustrated. Based on this study, it was found that evaporate minerals in Turpan Basin is the major factor that could affect the hydrochemistry changing of groundwater in different depth.  The evaporate minerals in this region are mainly derived from the surface soil, soil layer, vadose zone and Aydingkol Lake sediments.

    Experimental Study on the Filtration Capability of Clayey Soils in the Vadose Zone Prevention Nitrogen from Polluting Groundwater
    2016, 30(3):  688-694. 
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    The soil of unsaturated zone acts as a natural protector to the groundwater and it plays an important role in blocking the pollutants. Antifouling property in prevention nitrogen from polluting groundwater has been investigated through soil column leaching experiments. Three different sources-distilled water, recycled water and river water are used in the test. It is demonstrated that the soil used in the test has a strong capability in prevention nitrogen from polluting groundwater and the denitrification shows two different stages-stable and vola-tility dropped wherein the stable phase is the critical stage to compute the capacity. This papers presented a formula which considered the interval removal. The water sources have a significant effect on the flow rate and adsorption effects. The capability is affected by temperature changes. The column showed a strong ability to remove nitrogen when the temperature reached about 15 ℃.

    Engineering Treatment Effect Evaluation of Large-scale Wading Landslides in Badong County of the Three Gorges Reservoir Area
    2016, 30(3):  695-704. 
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    Engineering treatment effect of large-scale wading landslides in the Three Gorges Reservoir area has become a key issue that whether the reservoir can be in long-term normal operation. Taking the 15 large-scale wading landslides that have been treated in Badong County as the research object, this study summarized the large-scale wading landslides prevention and control engineering measures and analyzed the technical characteristics of large-scale wading landslide disaster prevention projects, and revealed that the anti-slide pile, slope protection engineering and drainage engineering have the highest utilization rate of engineering measures,and then pointed out the macro-deformation problems of engineering treatment based on the actual investigation.Combined with quantitative and qualitative evaluation method, this paper proposes an assessment approach with multi-levels and multi-factors. The index system was established according to the engineering treatment processes, survey results and the important factors that might change in the late operation. And based on the comprehensive evaluation value an evaluation standard was set up.The application case of XL01 landslide shows that this approach is practical and effective.Finally, this paper classified the large-scale wading landslides engineering treatment effect of Badong County according to the evaluation system. It comes to the conclusion that the engineering treatment has a good effect,but  there still have some problems.

    Landslide Susceptibility Evaluation Based on Weight-of-Evidence Modeling in the Xianshuihe Fault Zone, East Tibetan Plateau
    2016, 30(3):  705-715. 
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    Xianshuihe Fault zone is a sinistral-slip fault system on the eastern margin of the Tibetan Plateau with high Quaternary activity and frequently historic earthquakes. And large landslides are distributed along the fault zone. This paper investigated the landslide distribution characteristics in an approximately 7,339 km2 area and adopted Weight-of-Evidence Model (WOE) to develop landslide susceptibility evaluation. A detailed landslide inventory was prepared with a total of 415 landslides. Eleven landslide-causative factors were analyzed including slope angle, slope aspect, altitude, planform curvature, topographic wetness index (TWI), active fault, lithology, annual rainfall, rivers, roads and the NDVI of the study area. Susceptibility mapping schemes with WOE model were put out in this study and the assessment result with ROC method showed that the WOE model had got well result responses. The landslide susceptibility in the study area is controlled by the activity of Xianshuihe Fault zone, and is divided into five levels including no susceptible, low susceptible, moderate susceptible, high susceptible and very high susceptible according to landslide susceptible degree. The areas with very high and high landslide susceptibility are mainly distributed on both sides of Xianshuihe Fault zone from Donggu to Daofu County as well as Kangding County and Moxi town nearby. The moderate susceptibility areas are mostly along the tributaries of the deepcutting valleys and the roads. Besides, the low and no susceptibility areas are mostly distributed on high mountain areas where human engineering activity is weak, as well as areas where is relatively flat. The evaluation results reflect that the current situation of geological disasters in Xianshuihe Fault zone is well. The result can be used for the planning of geological disaster prevention and the major construction in the region.

    A Study on Soil Compression Characteristics in Land Subsidence Areas within Beijing
    2016, 30(3):  716-722. 
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    Numerous factors are attributed to the rapid development of subsidence in the plain area of Beijing. The existence of cohesive soils in this area provides the material foundation for subsidence, and therefore, this study focuses on the consolidation characteristics of cohesive soils with depth less than 100 m under different loading condition such as progressive loading, progressive unloading, and repeated loading and unloading in a typical subsidence area in Baxianzhuang within the Changping District of Beijing. According to the test results, the deformation of cohesive soils under progressive loading from 25 kPa to 1,600 kPa is greater than that of silt, which is 2.822 mm and 1.000 mm, respectively. The rebound of cohesive soils under progressive unloading from 400 kPa to 50 kPa is also greater than that of silt, which is 0.277 mm and 0.121 mm, respectively; and under repeated loading and unloading condition, silty clay and silt attain a state of consolidation faster than clay; the creep-time effect is sorted as clay>silty clay>silt. It is therefore recommended that a full consideration should be given to the effects of soil characteristics in subsidence areas when compiling land subsidence disaster prevention and control plans.