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    23 July 2010, Volume 24 Issue 4
    Water Resource and Environment
    Geochemical Characteristics and Families of the Crude Oils in the Yingmaili Oilfield, Tarim Basin
    LI Su-Mei, PANG Xiong-Qi, YANG Hai-Jun, XIAO Zhong-Yao, GU Qiao-Yuan
    2010, 24(4):  643-653. 
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    The genetic type of the oil in the Yingmaili Oilfield in the Tarim Basin is rather complex. Multiple geochemical approaches, including GC and GC/MS analysis of hydrocarbons in a gasoline range, biomarkers and aromatics fractions as well as compound specific isotope analysis of nalkanes, are adopted to characterize and classify oils in the area. Two main genetic oil families have been recognized in the Yingmaili Oilfield, namely marine oil family (I) in the YM2 wellblock and terrestrial oil family (Ⅱ) in the YM7 well-block, which have typical characteristics of marine and terrestrial oils respectively. However, further investigations show that there are still some differences in either of the oil families. The oil family Ⅱ is divided into two subgroups: One is primarily normal black and heavy oils produced form the Palaeozoic and Mesozoic intervals (Ⅱa), the other (Ⅱb) mainly condensate oils from the Eogene. There are some disparities of compound specific carbon isotope of nalkanes and distinctive differences  of the composition and relative distribution of aromatics in the oils. The Ⅱb oil is distinguished from Ⅱa by relatively high abundances of diphenyl and dibenzofurane series in aromatics, and significant advantages of various aromatics, such as naphthalene, phenanthrene and chrystane, each of which has a low molecular weight relative to that of the homologues with a high molecular weight. Furthermore, the Ⅱb oil is also characterized by a little heavier compound specific carbon isotope of nalkanes as compared with the Ⅱa. All those features of Ⅱb are similar to those of the oils in the adjacent Yangtake oilfield, suggesting that there must be a certain genetic relationship between them and that the former is likely to be mixedsource oils from the Mesozoic source rocks in the north Baicheng Depression of the Kuqu subbasin, which does not agree with the previous opinion about one genetic type of oil discovered there. Despite some similar biomarkers observed for the oil of family I in the YM2 wellblock, the distribution pattern of the compound specific carbon isotope of nalkanes in the oil of YM2 (O1) and YM201(O) wells in the block is impressively distinct, suggesting different sources and oil mixing probabilities. This study might be helpful for further source rock identification and hydrocarbons accumulation mechanisms unravelment as well as petroleum resource evaluation in the area.

    Geochemistry of the Jurassic Source Rocks in the South Qiangtang Basin,Tibet
    CHEN Wen-Bin, LIAO Zhong-Li, LIU Jian-Qing, FU Xiu-Gen, DU Bai-Wei
    2010, 24(4):  654-661. 
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    According to the surface samples and test data, the authors use analytic methods of Rock-Eval, microscopic observation, vitrinite reflectance, biomarkers comparatively and carbon isotope compositions of individual nalkanes to analyse the organic geochemical characters of the Jurassic source rocks in South Qiangtang basin. The result reveals that the organic matter abundance of source rocks is lower in Jurassic, the type of organic matter is mainly Ⅱ1, and the overall high degree of thermal evolution to achieve high mature stage. The organic source material is mainly low-grade hydrobios, the hydrocarbon source rocks form in a certain strong salinity reduction environment. Alkane isotope analysis show that it may be quite different in the parent material for the Jurassic source rocks in each formation. Dolomite oil seepage has a strong affinity with the mudstone source rocks of Xiali Formation in the study area.

    High-resolution Sequence Contrast and Its Oil/Gas Exploitation Significance of Lower Sand Section of Kumugeliemu Group of Quele-Yangta Well District in Kuqa Depression
    CAI Zhen-Zhong, ZHANG Li-Juan, LIN Chang-Song, LEI Yan-Ping, SU Zhen-Zhen
    2010, 24(4):  662-668. 
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    High-resolution sequence stratigraphy provides an important method for reservoir finely contrast in dense devoloping well area. Bounded by the relatively steady transgrassive surface, there can be divided 4 4th order sequences and 6 5th order sequences in the lower sand section of Kumugeliemu Formation. Finely sequence contrast and depositional microfacies analysis show that there were mainly delta front deposit of drought salt lake environment in Yangta developing district, and formed 3 to 4 steady distributional fine grainsize sands, which came from eastern and southeastern uplift area, and reflected the fluvial long-distance transportation. In Quele developing district, the sandbody was thicker variable, which reflected the near fan or braided fluvial delta deposit characteristic. Three thick sandbodies wich are in braided channel, delta front mouth bar and subdistributary channel developed during 3 transgressiveregressive cycles can be recognized. From the northwestern to the southeastern, the sand gradually thinner, and reflected the clastic system coming from western Wensu uplift. Paleo-geography restructure shows that the two well districts developed under two different depositional systems, and there was a bay between them. The difference of sequence and depositional system decided the reservoir distribution and oil field development scheme.

    Sedimentary Filling Evolution and Tectonic Control of the Lower Cretaceous of the Wunan Depression in Hailaer Basin
    CHU Cheng-Lin, LIN Chang-Song, ZHU De-Feng
    2010, 24(4):  669-677. 
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    According to the recognition and division of the sequence boundaries, the Lower Cretaceous of Wunan depression can be divided into five two-order sequences and seven third-order sequences. Wunan depression is composed of western steep slope zone, eastern gentle slope zone, Wunan sag, Wuzhong uplift and Bayantala fault zone. Each sub-structural unit constrains the development and distribution of sedimentary systems. The tectonic subsidence analysis suggests that the evolution of the Wunan depression can be divided into five stages: early rifting stage, initial rifting stage, intense rifting stage, rifting-subsiding stage and subsiding stage. Alluvialvolcanic basin sequence, alluvialshallow lacustrine basin sequence, semi-deep lacustrine-deep lacustrine basin sequence, semi-deep lacustrine basin sequence and shallow lacustrine basin sequence are developed respectively. The evolution and sedimentary facies of each two-order sequence was controlled by the different stages. The slope region in the east and the Bayantala fault zone are the favorable reservoir belts.

    Sequence Stratigraphy Mode and Lithologic Traps Prediction of Napo Formation in South Block of Oriente Basin,Ecuador
    TIAN Ji-Jun, JIANG Zai-Xin, CHEN Shi-Wang
    2010, 24(4):  678-684. 
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     Napo Formation in south block of Oriente basin can be divided into 5 sequences according to sequence boundaries,such as unconformity and seismic reflective characteristics. Shelf margins systems tracts, marine  transgressive and highstand systems tracts can be subdivided by the stacking patterns of stratigraphy, changes of lithology and lithofacies. Shelf margin systems tract is characterized by the tidal flat,lacustrine transgressive systems tract is charaterized by the wide spread of marine mudstone sedimentation, and highstand systems tract is featured by the subaqueous shoal sandstone.It is identified that tide channel sandstone is the high quality reservoirs in south block, tide channel sandstone,M1 lithologic pointout zones,subaqueous shoal sandstone are the favorable lithologic traps. The oil shale of the Napo Formation marine shale can offer platitudinous hydrocarbon. The south block locates in the favorable directional zone of oil and gas migration. Hydrocarbon accumulation is in condition of poolforming. Tide channel sandstone growing area is the beneficial exploration directions by integrated forecasting.

    Characteristics and Classification and Evaluation of Low Porosity and Permeability Reservoir in Shahejie Formation of BZ25-1 Oilfield
    YANG Yu-Qing, PANG Fu-Xi, TIAN Hong, XU Jin, CHEN Li-Qun
    2010, 24(4):  685-693. 
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     BZ25-1 oilfield is located at southern Bohai Bay. The Shahejie Formation which is the main reservoir is a typical lower porosity and permeability reservoir. For the purpose of studying the petrological characteristics, sedimentary characteristics, physical properties and pore structures of the reservoir, a large numbers of thin sections, scanning electron microscopes, Xray diffraction analysis and well logging data were analyzed. The sedimentary characteristics of Shahejie Member Ⅲ is of turbidite fan deposition of deepwater lake environment, while Shahejie Member Ⅱ is of fan delta deposits. Debrisfeldspar sandstone is the main lithology of this area. The pore types in the reservoir are as follows: mixed pore, secondary pore and primary pore. For the dissolved pore in Shahejie Member Ⅲ is less than that in Shahejie Member Ⅱ, the physical properties of Shahejie Member Ⅲ are worse than those of Shahejie Member Ⅱ. With the oil testing verification of reservoir, three types of classification and evaluation of lower porosity and permeability reservoir which are  the macrocauses, microscopic pore structure parameter and comprehensive methods are put forward. Generally the reservoir is subdivided into three categories as follows: good, medium and poor reservoirs, and their corresponding productivity are more than 80 m3/d, between 10 and 100 m3/d, less than 10 m3/d and micro amounts or no productivity,respectively. After the testing verification of 15 reservoirs of the Shahejie Formation in 5 wells of the oilfield, the coincidence rate of the result of macrocauses classification and evaluation and the testing result is 86.67%, and the result of microscopic pore structure parameter classification and evaluation basically tallies with the testing result.

    Lithologic Reservoir Prediction of Saertu Formation in  Taikang-Xichao Area of North Songliao Basin
    ZHANG Yin-Guo, LI Yu-Le
    2010, 24(4):  694-702. 
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    Daqing oilfield has been explored in a high degree, so exploring lithology reservoir become a very important way to increase the oilfield reserves. According to TaikangXichao area geology setting that is a flat monocline, this thesis studied the petroleum geology condition of forming lithology reservoir based on geology structure character, hydrocarbon source rock, sedimentary character and hydrocarbon migration. In S2+3, S1, S0, upward pinchout, formation onlap, sand lens and combination lithology reservoir are developed, and this study also characterize these different lithology reservoir formation characters. By combining depositional subfacies distribution study and post-seismic impedance inversion study, the main lithology reservoir distribution of this area is predicted, and it is considered that formation onlap lithology reservoir and combination reservoir are mainly developed in S2+3.Onlap lithology reservoir are mainly distributed in the middle and west area, and the combination reservoir is mainly distributed on Alaxin tectonic belt. Upward pinchout, formation onlap, sand lens lithology reservoir are all developed in S2+3,S1,S0.This lithology reservoir study is significant to the future hydrocarbon exploration.

    Discussion on Types of Upper Paleozoic Gas Reservoirs in Ordos Basin
    ZHAO Zhong-Ying, LIU Guan-Di, SUN Ming-Liang, Wang Lu
    2010, 24(4):  703-708. 
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    In order to estimate whether the Upper Paleozoic gas reservoirs in Ordos Basin are deep basin gas reservoirs or not, the accumulation conditions, accumulation periods and gaswater distribution regularity were studied and compared with those of the deep basin gas reservoirs in Alberta Basin. The results show that the Upper Paleozoic gas reservoirs in Ordos Basin have the characteristics of extensive distribution of source rocks, unobvious gas generation center, low gas generation rate, bad persistent and decentralized gasproviding condition, so that the force of gas driving water is not enough to form deep basin gas reservoirs for the Upper Paleozoic natural gas. For the low porosity and permeability, strong heterogeneity, similar distribution direction between sand bodies and regional structure, surrounded by mudstones in the updip direction, the Upper Paleozoic reservoirs in Ordos Basin were different from those of deep basin gas reservoirs characterized by porosity and permeability being better and better along the updip direction.  The sourcereservoir assemblage styles, with limited contact areas between source rocks and reservoirs due to small scale and discontinuous sand bodies, are “selfgeneration & selfaccumulation” and “sand bodies superposed on source rocks” and are different from those of deep basin gas reservoirs which have great scale contact areas. The Upper Paleozoic gas reservoirs have three accumulation periods including the burial and uplift periods of basin, experienced strong late reformation, and dont have the conservation condition of deep basin gas reservoirs. Gas and water, controlled by the physical properties of reservoirs and the regional structure, have complicated distribution, unobvious partition and no “gas-water inversion” interface resulted from gas driving water in the reservoirs. The characteristics of the Upper Paleozoic gas reservoirs in Ordos Basin show that the Upper Paleozoic gas reservoirs are the stratigraphic gas reservoirs mainly controlled by the physical properties of reservoirs and not deep basin gas reservoirs. This indicates that the study of favorable reservoirs should be paid more attention in the future petroleum exploration.

    Hydrocarbon Accumulation Characteristics of Reservoir in Fula Depression and Their Implication for Petroleum Exploration, Muglad Basin, Sudan
    HE Bi-Zhu, WANG Wang-Quan, LV Yan-Cang
    2010, 24(4):  709-718. 
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    Before the discovery of Fula oilfield, previous studies consider that there developed source rock of semi-deep to deep lacustrine in Abu Gabra Formation,Fula depression,which were comprehensively evaluated to be good to very good source rocks but with lower thermal evolution degree, and the other main factors controlling the formation of oil pools were uncertainty, so Fula depression were considered lack of the oil and gas exploration potential. Based on detailed study of gravity data, seismic data and well data, analysis stratigraphic sequence, structure development and evolution, sedimentary facies combined with lithofacies, log-facies and seismic facies, this study reveals that the development of structure and deposition in Fula depression were controlled by shear-extensional regional tectonism. There developed a certain and effective hydrocarbon generation sag of the Abu Gabra Formation in Lower Cretaceous. Three favorable sourcereservoirseal assemblages and 4 reservoirforming zones are identified. The rollover anticline-faulted nose zone in the middle structure belt, the faulted noses zones in west margin of south sub-depression, in the south faulted step belt and in east margin of the north subdepression are evaluated prospect reservoir plays. Fula 1 rollover anticline and Fula 2 faulted nose are regarded as the best of prospect targets. These study results play an important role on oil and gas exploration and development in Fula depression. This research methods and exploration strategy can provide references for early petroleum exploration and basin analysis.

    Controls of Plate Motions on Subsidence and Filled Characteristics of  the Cenozoic in Chinese Offshore Basins
    LI Yun-Zhen, DENG Yun-Hua, XU Qiang, YU Xin-He
    2010, 24(4):  719-726. 
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     The evolutions of the Pacific Plate, the Indian Ocean Plate and the Eurasian Plate have the controlling effect to the subsidence and filled characteristics of the Cenozoic in Chinese offshore basins.According to the characteristics of mantle convection and crustal stretching, the subsidence types of Chinese offshore basins can be divided into passive, initiative and combination thermal subsidences. The different subsidence types of sedimentation basins have different basin structures. Rift is the main type in the passive thermal subsidence. Depression is the main type in the initiative thermal subsidence. Vertical or lateral overlapping is the main type in the combination thermal subsidence. The passive thermal subsidence is the main type in northern Chinese offshore basins in internal plates. As away from the sea, these basins are less affected by the transgression which is dominated by the continental sedimentary system. Central Chinese offshore basins in plate margins have the subsidence characteristics which the initiative overlaps the passive in a lateral direction with shallow water, small slope break and delta. Southern Chinese offshore basins in plate margins also have the subsidence characteristics which the initiative overlaps the passive in a lateral direction with deeper water, large slope break and delta.

    Characteristics of ShangkouNankou Fault and Its Influence on Seepage Stability of Huyu Dam, Beijing
    LI Gong-Jian, WANG Qing-Fei, WANG Bi-Ren, LIU Xue-Fei, LIU Yan-Bing
    2010, 24(4):  727-734. 
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    Nankou is located in the transition region between Jundushan uplift and the hill-plain area of western Beijing. The systematic fieldinvestigation, terrain analysis, statistical analysis of joints and microscopic structure studies of bedrock are applied in our works. It is suggested that the overall performance of Shangkou-Nankou fault is normal, it experienced mechanical process from compression into tension after it had originated in Early Yanshanian, while the corresponding principal stress σ1 in Jurassic is NW-SE and it translated into NEE-SWW from Early Cretaceous. The latest active period of Shangkou-Nankou fault is Late Pleistocene, and the modern crustal movement of the reservoir area is less stable. The intensive joints in bedrock are the dominant factors for dam seepage and the most effective joints which approximately parallel to the river toward are controlled by early NW-SE compression. A stabilization works should be carried out in order to improve storage capacity of the reservoir.

    Evolutional Impacts of Extensional Linkage Fault System in Dongpu Sag
    CHENG Xiu-Shen, CHEN Fa-Jing, QI Jia-Fu, DENG Jun
    2010, 24(4):  735-743. 
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    Dongpu sag NNE main basement fault extending with increasing depth intersects the deeper decoupling detachment fault and connects to the induced transfer faults in various manners,constituting the extensional linkage fault system in Dongpu sag.Linkage fault system in different sections of Dongpu sag is characterized by diverse geometrical and kinematical features. Northern Lanliao main fault plane develops a comparatively modest formation while the extensional linkage fault system is primarily composed of domino-style halfgrabens. Central extensional linkage fault system commonly exhibits an asymmetrical graben located in the hanging-wall of large listric normal fault. Southern Lanliao fault plane shows a rampflat shape, a relatively complex rift structure. The evolution of extensional linkage fault system in Dongpu sag can be roughly divided into four periods and evolutional styles, which exert significant impacts on Paleogene sedimentary and petroleum geological conditions.

    Comparative Analysis of Inversion Structure with Its Easily Confused Structures
    LIU Jian-Bao,XIA Bin, LV Bao-Feng, CAI Zhou-Rong, SHI Qiu-Hua
    2010, 24(4):  744-748. 
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     Comparisons between negative inversion faults and the “seesaw” structures, positive inversion folds and gravity slideshaped graben antiforms, layer compensation antiforms and diapirs antiforms, positive inversion faultspropagation and the rollover anticlines are discussed. Negative inversion faults and the “seesaw” structures have the similar external form of a reverse wedge, but the latter is formed by different fault activity in a unified regional stress field. Positive inversion folds and antiforms have similar profiles, but are different in the strata thickness, erosion degree, axial face, and associated structures. The formers strata are thick in the middle but thin in wings, and strata denudation thickness is lower in the wings, and it's strata overlap to the fold center above the unconformity. Gravity slide-shaped graben antiforms and layer compensation antiforms are under the control of regional tensile stress, so there is no erosion at the top of the strata, and no characteristics of middle strata thick but wings thin. Gravity slide-shaped graben antiform is the result of local pressure in regional tensile stress, so its size is small. Diapirs antiform is cross-bend fold with lateral stress-free, so its axial is always upright, and its associated structures such as depression of salt side and the top faults cluster are developed. Positive inversion faults-propagation and rollover anticline both develop anticlines on the fault hanging wall, but their anticline shapes, sizes, and strata thickness characters are different. Rollover anticline is controlled by contemporaneous faults, so its anticline area is small and height is little, and its axial basically parallels to the fault plane. Its denudation is not obvious at the top of strata and its strata thickness varies small laterally compared to the concaveconvex “horn-type” strata of positive inversion faults-propagation.

    Structural Characteristics and Hydrocarbon Accumulation of Relay Ramp in Liaoxi Lowuplift, Bohai Bay Basin
    YANG Ming-Hui, ZHOU Xin-Huai, WEI Gang, LIU Le, LI Chun-Xia
    2010, 24(4):  749-754. 
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     Relay ramp is an important structural style to accommodate regional strain balance.According to new 3D seismic data interpretation, fault displacementdistance relation and seismic coherence slice analysis, this paper discussed some features of the relay ramp in Liaoxi low-uplift, Bohai bay basin, and briefly analyzed the relationship between relay ramp and hydrocarbon accumulation of buriedhill reservoir.The seismic profile interpretation indicates that the relay ramp of buriedhill belt in Liaoxi low-uplift connects footwall of Liaoxi No.1 fault and hangingwall of Liaoxi No.2 fault.On the seismic coherence slices, lateral connection with Liaoxi No.1 fault and Liaoxi No.2 fault is very clear.However, according to the fault displacementdistance relation, Liaoxi No.1 fault displacement is gradually transferred to Liaoxi No.2 fault along the faults strike. At the same time, this displacement is fundamental to maintain conservation in relay ramp.The relay ramp's significance for hydrocarbon accumulation is mainly exhibited in the formation and transformation of buriedhill reservoir.High quality reservoir is the material base of JZ25-1S buried-hill hydrocarbon reservoir

    Control of Faults on Hydrocarbon Migration and Accumulation in Nanpu Sag, Bohai Bay Basin
    LI Hong-Yi, JIANG Zhen-Xue, DONG Yue-Xia, WANG Xu-Dong, QI Li-Xin
    2010, 24(4):  755-761. 
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    Based on the classification of faults, using geology statistics and geochemical analysis, the controlling effects of faults on hydrocarbon migration and accumulation in Nanpu Sag are expatiated from macroscopic aspects to microscopic aspects. Faults are divided into three types including the long active fault, the early active fault and the lately active fault. The long active fault, acting as source fault, was important pathway for vertical hydrocarbon migration, and multi oilbearing layers were formed as a result of multiphase activity of the long active fault. The vertical distribution of hydrocarbon was controlled by the phase and intensity of fault activities, and the reservoir was distributed in the traps surrounding source faults. The function of fault for hydrocarbon migration and accumulation was various in different time. The reverse fault-screened trap has better oil-bearing property than the co-dip fault-screened trap, which is favorable target for oil exploration. The reservoir scale of faultscreened trap was controlled by sealing ability of screened fault, so the estimation of fault-sealing has great significance for improving the success rate of drilling.

    Geological and Geochemical Characteristics of Granite in the Daolangshan Region, Inner Mongolia
    GUO Min, LI Xiang, HU Xiang-Zhao, Zou Hai-Yang
    2010, 24(4):  762-766. 
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    The Daolangshan region is located in the northern margin of North China PlateThe outcropped rockbody are mainly Yanshanian biotite granite.Geochemical data show characteristics with rich aluminum,rich silicon and poor calcium contents.The rock Rittman index is an average of 1.80 and alkalinity index is an averaged of 2.6,belongs to calc-alkaline granite. The rockbody has a high differentiation index value, with a high degree of crystallinity evolution.The  total REE content of granite body is low,with an obvious negative Eu anomaly.It is concluded that the rock body is formed from partially melting of the high maturity shale rocks in the low temperature

    Carbon and Oxygen Isotope Compositions of Gangue Carbonates in Pb-Zn Ore Deposits in Luanchuan District, Southwest Henan Province
    DUAN Shi-Gang, XUE Chun-Ji, FENG Qi-Wei, GAO Bing-Yu, LIU Guo-Yin
    2010, 24(4):  767-775. 
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     It has been made a big progress in Pb-Zn Prospecting in southwestern Henan Province recently.Especially, more than ten vein groups of Pb-Zn-Ag mineralization (more than 100 Pb-Zn-Ag veins) have been found in Luanchuan district, which shows a broad prospection of Pb-Zn-Ag resources.The scientific research on these Pb-Zn-Ag ore veins enriches knowledge on regional metallogeny of southern margin of North China Craton and promotes the pace of Pb-Zn prospecting.Pb-Zn ores in Luanchuan district occur in skarn around Yanshannian porphyries or in fractures (vein type) peripheral to Yanshannian porphyries.Gangue carbonate of vein type Pb-Zn ore has carbon and oxygen isotope compositions (Chitudian Pb-Zn deposit: δ13C ranges from-3.66‰ to -2.82‰ and δ18O ranges from   10.31‰ to 15.86‰; Bailugou Pb-Zn deposit: δ13C ranges from -3.00‰ to 1.80‰,δ18O ranges from 9.40‰ to 17.70‰; Lengshuibeigou Pb-Zn deposit: δ13C ranges from -4.90‰ to -0.40‰,δ18O ranges from 6.00‰ to 12.50‰) between typical marine limestone (δ13C is 0 ± 2‰,δ18O ranges from 28‰ to 30‰) and magmatic rock (δ13C ranges from-3‰ to -30‰,δ18O ranges from 6‰ to 12‰;mantle: δ13C ranges from-5‰ to -7‰), which shows the ore forming fluid and metals bear characteristics of dual function and both sources of magma and strata.It can be concluded from synthetic analysis that Pb-Zn ore deposits in Luanchuan district are skarn type or magmatic hydrothermal filling-metasomatic type

    Trace Element and REE Geochemical Characteristics of Sandstonetype  Uranium Deposit in the Dongsheng Area of the Ordos Basin,China
    XUE Wei, Xue-Chun-Ji, Chi-Guo-Xiang, Peng-Yun-Biao, WANG Kai
    2010, 24(4):  776-784. 
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    This study examines the geochemical characteristics of the Dongsheng sandstonetype uranium deposit in the Ordos basin in order to find geochemical signals that are useful for uranium deposit exploration. Trace element analyses were carried out for uranium ores, uraniummineralized sandstones, and nonmineralized country rock (sandstones and shales). The results indicate that Pb and Mo have close relationships with uranium mineralization, with the highest concentrations in the uranium ores, then in the uraniummineralized sandstone, and lowest in country rocks. Therefore, Pb and Mo can be used as indicator elements for uranium mineralization. This is reflected by the “W” pattern (three peaks representing Pb, U and Mo) in the spider diagram. REE patterns suggest that the ores, mineralized sandstones and nonmineralized country rocks were initially formed from the same material sources, sedimentary environments and tectonic settings. The fact that some of the uranium ores are enriched in HREE relative to other uranium ores suggests two stages of uranium mineralization, a diagenetic stage overprinted by a hydrothermal mineralization.

    Electronic Microscopy Study on the Uranium Minerals of Dongsheng Sandstonetype Uranium Deposit in Ordos Basin
    MIAO Ai-Sheng, LIU Qi, LIU Hui-Fang, XIAO Ping
    2010, 24(4):  785-792. 
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    Dongsheng uranium deposit in Ordos basin is an important large sandstone-type uranium depositBy electronic microscopy, the thesis has made a detailed research on the uranium minerals category and output characteristicsIt has been identified that the main uranium minerals are coffinite and ursilite which are both epigenetic mineralThe diameters of uranium mineral's granule are very tiny, usually at micron (μm) level-Coffinite and ursilite are commonly tabular and irregularly granular, with an obvious phenomenon that is eroded on their surface, and some of them have eroded pore at nanometer (nm) degree; they are closely associated and have a close relationship with biotite and pyrite eroding. It can also be found that micro-vein uranium assemblages penetrate through the quartz clast.It has been researched that the uranium element is dissolved (transferred) and deposited (enriched) repetitively under the epigene.

    Clay Mineralogy and Its Palaeoclimatic Indicator of the Late Paleocene to Early Oligocene  Sediments in Yongdeng, Lanzhou Basin
    DENG Yan-Ping, HONG Han-Lie, YIN Ke, XU Yao-Ming, DU Juan, ZHANG Ke-Xin
    2010, 24(4):  793-800. 
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    Clay mineralogy of the Late Paleocene to Early Oligocene sediments in Yongdeng, Lanzhou and their palaeoclimatic interpretations were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Our results showed that clay mineral composition of the sediments was dominantly illite, smectite, and chlorite, with minor palygorskite. From the Late Paleocene to Early Oligocene sediments illite content showed an upward increase trend, while the smectite content exhibited an opposite trend to that of illite. There were a sharp decrease in illite content and a rapid increase in smectite content at ~55 Ma in the curves of clay mineral composition. SEM observation showed that smectite flakes were replaced by authigenic palygorskite along the particle edges. Palygorskite derived from smectite usually displayed a hairlike shape, while the detrital palygorskite exhibited a short club outline. Clay mineralogy of the sediments indicated that arid/semiarid climate prevailed over the Late Paleocene to Early Oligocene period, but it changed from relatively humid to arid/semiarid conditions in Lanzhou basin, which was controlled by the global climate system, i.e, the planetary wind system, and the sharp change in illite and smectite contents at ~55 Ma indicated the global PETM event recorded in the area.

    Geochemical Subdivisions in Metallogenic Belt with the 1∶200,000  Stream Sediments and Its Geological Significance: A Case Study in Gangdese Copper-polymetallic Metallogenic Belt
    WANG Yong-Hua, GONG Peng, GONG Min, MA Zhen-Dong
    2010, 24(4):  801-806. 
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    By taking Gangdese copper-polymetallic metallogenic belt as an example, methods and thoughts to carry out geochemical subdivisions in metallogenic belt scale using 1∶200,000 and 1∶500,000 stream sediments data are expounded, and further the geological significances are discussed. Results show that geochemical data of the small-scale stream sediments have tracer significance for geochemical subdivisions;therefore a set of operable geochemical subdivisions methods is summed up,which is beneficial for prospecting direction and referenced for tectonic subdivisions. In short, the geochemical subdivisions can guide for prospecting direction, mineral evaluation and basic geological survey.

    Geochemical Characteristics and Sources Identification of Atmospheric  Particles in Southern Song-Nen Plain in Heilongjiang Province
    WEN Yu-Bo, YANG Zhong-Fang, XIA Xue-Qi, CHENG Xin-Bin
    2010, 24(4):  807-815. 
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    Twenty-eight samples of atmospheric particles were collected from the southern area of Song-Nen plain, during the summer of 2008. Both the major and minor element concentrations in the samples were analyzed in this research. This paper shows the mass concentrations, correlations and spatial distributions of the elements. And also, the sources of the various elements were identified by enrichment factors and factor analysis. The results show that the elements which are abundant in PM10-100 particles are those which have high concentrations in the crust. Heavy metals have relatively high concentrations in the PM2-5 particles. Mass concentrations of atmospheric particles decrease as: Daqing > Suihua > Harbin > Qiqihar. The enrichment factors of Fe, K, Ti, Mn and Co are smaller than 1 or very close to 1. As for Ca, Mg, Ni and Cr, the enrichment factors are greater than 1 but still smaller than 10. Whereas the enrichment factors of Na, Zn, Cu, Cd, Pb and Se are greater than 10, indicating these elements have anthropogenic sources. The varimax rotated factor analysis shows that the major source of atmospheric inhalable particles is soil dust. Other sources include coal combustion, garbage incineration, automobile tail gas, alkali dust through atmospheric transmission, fuel combustion and industrial sources.

    Heavy Metal Distributions and Its Source  of Soils at Great Wall Station,Antarctica
    SU Jing-Wen,XING Guang-Fu, GE Wei-Ya, JIANG Yue-Hua
    2010, 24(4):  816-820. 
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     Soil samples around Great Wall Station were sampled to analyse their contents and distribution characteristics. Comparison of soil heavy metal between this result and previous research results in the past 20 years showed that eight different heavy metals had appeared enrichment trend. Through comprehensive analyses, the movement of automobiles including emission, gasoline leakage etc. may be one of the main reasons of metal richment. So more effective management of all the mans activities at Antarctica are necessary.