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SequenceStratigraphic Features and Their Paleogeographical Implications for the Mesoproterozoic of the Southern Margin of Wutai Mountain: A Case Study of the Chenjiazhuang Section in Wutai County of Shanxi Province, North China MEI Min-Xiang Geoscience    2010, 24 (5): 888-899.   Abstract （9907）      PDF（pc） （14980KB）（24783）       Knowledge map    Save The study area, i.e. the southern margin region of the Wutai Mountain, is a conjoining region between the Jin-Yu-Shan in the southern part and the Yanliao Rift Troughs in the northern part of the Mesoproterozoic in the North-China Craton. A set of clastic rocks of the tidalflat deposition system makes up the Changzhougou Formation, and a set of tidalflat carbonate rocks does the Gaoyuzhuang Formation, both of which constitute the Mesoproterozoic of the study area. Its bottom boundary is an angular unconformity covering the Paleoproterozoic Hutuo Group, and top boundary is a leurodiscontinuity with a stratigraphic hiatus more than 1,000 Ma underlying the Cambrian system. Thus, the incomplete strata of the Mesoproterozoic become a true example for the study of sequence stratigraphy in the Precambrian, which is the key to peek the trangressive process from the Jin-Yu-Shan in the southern part in the early period and that from the Yanliao Rift Troughs in the northern part during the Mesoproterozoic in the study area, and provides a valuable stratigraphic record to correlate strata that remain uncertain. Further, the research and introduction on sequence-sequence features that are marked by depositional successions for the Mesoproterozoic at the Chenjiazhuang section in Wutai County of Shanxi Province will provide a useful clue for further study on the Precambrian sequence stratigraphy in the North-China Craton. Reference | Related Articles | Metrics | Comments（0）

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Subducting Characteristic of the Pacific Slab Beneath Northeast China JIANG Guo-Meng, ZHANG Gui-Bin, XU Yao Geoscience    2012, 26 (6): 1125-1135.   Abstract （9675）      PDF（pc） （12400KB）（21917）       Knowledge map    Save  The volcanoes locating in northeast China are very active. Some researchers consider that the origin of volcanoes is closely related to the subducting western Pacific plate and the upwelling asthenosphere. The thickness and the existing range of the subducted plate are not clear as far although the seismic tomography results obviously show that the Pacific plate exists below the volcano region. Therefore, in this study, we adopted the method combining the teleseismic tomography with travel time forward modeling to further study the velocity structure beneath northeast China, especially the precise model of subducted Pacific plate. Our results show that (1） the average thickness and velocity perturbation of slab are 85 km and 1%, respectively, and the slab has not been thickened compared with the previous result of the Japan Sea; (2） the Pacific plate subducted into the mantle transition zone with a shallow dip angle, and changed horizontally when it touched the bottom of mantle transition zone, and extended westward to Longitude 127°E and then stops over there; (3） the horizontal slab locates right below the volcano region. These above features help people understand the origin of intraplate volcanoes and the geodynamical process better. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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Recharge to Shallow Aquifer to Control Land Subsidence due to Construction in Shanghai City WU Jian-Zhong, WANG Han-Mei, YANG Tian-Liang Geoscience    2009, 23 (6): 1194-1200.   Abstract （9395）      PDF（pc） （5791KB）（21430）       Knowledge map    Save Land subsidence in Shanghai is mainly affected by groundwater withdrawal and large-scale construction. Land subsidence occurred by large-scale construction becomes increasingly obvious with the enforcement of groundwater withdrawal management, and affects the safety of construction and working of surrounding lifeline engineering. The study of mechanism and prevention of land subsidence due to construction is low, and the prevention technological system hasn`t been built. To control land subsidence occurred by construction dewatering, this paper introduces the mature technology of artificial recharge in deep confined aquifer to shallow aquifer via test study. Because the sand stratum structure and hydrodynamic condition of shallow aquifer is different with the deep one, the technics and methods of artificial recharge is also different. This test improve on the technics and methods of artificial recharge to suit the shallow aquifer, and monitoring the land surface deformation synchronously to analysis the effect of artificial recharge. To generalize the application of artificial recharge to shallow aquifer, this paper discussed the feasibility and applicability of adopting artifical recharge technology to shallow aquifer in Shanghai. Related Articles | Metrics | Comments（0）

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Study on Thrust Nappe and Sliding Nappe Structures of Mesozoic-Cenozoic in the Nancheng Area, Jiangxi Geoscience    2016, 30 (1): 97-109.   Abstract （9545）      PDF（pc） （4923KB）（19154）       Knowledge map    Save Based on geological surveying and drilling verification of stratum contact relations both between Jurassic Linshan Group and underlying Pre-Jurassic metamorphic strata and between Cretaceous and Pre-Cretaceous strata, this study has newly found the Xiejia structural window, Zhuyouxincun structural window, Shangwushi structural window and Wangtianshi klippe, and moreover, has determined the Yanshanian glide and Himalayan thrust nappe structures in Nancheng area, Jiangxi. The Yanshanian glide structure occurred in the end of Middle Jurassic along the expanding surface from unconformity surfaces between D-T2/T3-K1 (gliding nappe) and lower strata (underlying strata). The dynamics of glide structures maybe relate to the subduction of Pacific plate from southeast toward northwest. The large-scale Himalayan thrust nappe structure had thoroughly altered the former strata sequence and formed present tectonic framework. This framework is composed of multiple imbricated thrust and stacking faults (bedding and crossbedding) and behaves a feature of lateral zonation and vertical stratification. The allochthon Pre-Cretaceous mass thrusts from southeast toward northwest and stacks on the autochthon Cretaceous strata. The autochthon Cretaceous strata exhibit some windows around by Pre-Cretaceous. The dynamics of Himalayan thrust nappe structure is complicated and maybe relate to the distant effect of the collision between the Eurasian plate and the Indian plate. Related Articles | Metrics | Comments（0）

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Study on the Evaluation Method of Fault Sealing and Its Application: An Example of Neogene Layer in Enping Sag, Pearl River Mouth Basin Geoscience    2016, 30 (1): 122-129.   Abstract （9302）      PDF（pc） （2853KB）（18981）       Knowledge map    Save Taking the Neogene layers of the Enping sag as an example, a new way to evaluate fault sealing of structural closure is introduced under the current exploration practice to calibrate critical values, that is, obtaining clay content in fault zone, shale smear value and normal pressure of fault surface from sealing rules of faulted reservoir. The results show that the threshold values of shale smear factor in drilled faulted reservoirs gradually increases with depth. Development of shale and its content of fault zone are prerequisites for fault sealing, and the evaluation of fault sealing is affected by structure map accuracy, structural adjustment and fault activity. The risk of fault sealing, including faults vertical and lateral sealing, could be analyzed by the evaluation method, so as to improve the success ratio of fault traps exploration. And the evaluation method could be applied to the new exploration area with the similar tectonic genesis and sedimentary background as Enping sag, which is an effective methods to evaluate fault sealing during the early exploration periods. Related Articles | Metrics | Comments（0）

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Geoscience    2016, 30 (1): 0-.   Abstract （9419）      PDF（pc） （3280KB）（18896）       Knowledge map    Save Related Articles | Metrics | Comments（0）

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Geochemical Characteristics and Tectonic Implication of Rilang Formation Basalt in the South Tibet, Zhongba County, Tibet, China Geoscience    2016, 30 (1): 69-77.   Abstract （9574）      PDF（pc） （4324KB）（18827）       Knowledge map    Save Lower Cretaceous volcaniclastic litharentites are widely distributed in the Tethyan Himalaya, while less research was reported about the provenance of these volcaniclastic litharentites. In this paper, we report sedimentray and geochemical characteristics of basalts in Rilang Formation of central-western Tethayan Himalaya. Major and trace element compositions show that these basalts belong to alkaline basalt. They are enriched in LREE relative to HREE, similar geochemically to Ocean Island Basalt (OIB) and intra-plate basalt. The contents of Nb fall between the upper crust and lower crust. These basalts have a relatively low content of Th than that of lower crust and relatively high Th/Nb ratio, low Ce/Pb ratio,which indicates that these basalts suffered variable crustal contamination. Sedimentary and geochemical characteristics of these basalts are apparently different from seamounts basalt in the Yarlung-Zangbo ophiolitic mélange belt. The tectonic setting discrimination diagrams based on trace elements suggest that basalts of the Rilang Formation formed in intracontinental rift environment. Combining the petrology and depositional environments of sedimentary rocks, we conclude that these basalts maybe the one of the provenance of volcaniclastic litharentites of the Rilang Formation. Related Articles | Metrics | Comments（0）

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Pop-up Structure in Fold-and-thrust Belt and Its Implications: An Insight from Analogue Sandbox Models of Thrust Wedge Geoscience    2016, 30 (1): 110-121.   Abstract （9644）      PDF（pc） （8533KB）（18780）       Knowledge map    Save Pop-up structure is widely developed in fold-and-thrust belt and strike-slip tectonic setting, and has been paid much attention for its great significance in petroleum exploration. Analogue sandbox modeling has proved to be a powerful visual tool for simulating such complex structures in various tectonic settings. This study conducted a series of sandbox modeling to unravel the difference in structural geometry of pop-up structure during the development of fold-and-thrust belt, based on the same initial condition with various shortening velocities (0.3 mm/s, 0.1 mm/s, 0.005 mm/s). From the modeling results, two types of pop-up structures, i.e. superimposed and simple pop-up structures, would be developed in thrust wedge depending on different shortening velocities. In particular, there is a significant difference between superimposed structure and simple pop-up structure. The wedge shows simple deformation styles characterized by simple pop-up structures and increasing deformation while propagating continuously towards foreland. The propagation way of analogue sandbox models of thrust wedge has a significant control on the types of pop-up structure. Forward-breaking propagation took place in the foreland, mainly developed from simple pop-up structure; back-breaking propagation occurs in hinderland, mainly developed from superimposed pop-up structure. Related Articles | Metrics | Comments（0）

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Sedimentary Sequence and Environment of Shuangqiaoshan Group from the Adjacent Area Between Anhui and Jiangxi Geoscience    2016, 30 (1): 130-143.   Abstract （9712）      PDF（pc） （2215KB）（18648）       Knowledge map    Save The adjacent area between Anhui and Jiangxi is located in the northern margin of the eastern section of Jiangnan orogenic belt, in which Shuangqiaoshan Group is widely distributed in a large-thickness and low-grade greenschist-facies metamorphic flysch formation which is given priority to with argillaceous-arenaceous metamorphosed fine clastic rocks and contains a small amount of volcanic rocks. Synthesizing analysis of rock assemblages and sedimentary structures shows that Shuangqiaoshan Group may be formed in a set of volcanic-terrigenous clastic rocks which can be divided into four stages of sedimentary facies about the bathyal-shelf margin slope, neritic shelf, shelf slope and shelf slope-shelf facies under tectonic background of continental margin island arc, indicating the shrinking-closing stage of the basin evolution during the period. The proximal source region and discontinuous incomplete Bouma sequence of Hengyong Formation and Anlelin Formation, mainly generated by turbidity current and few by sandy debris flow, respectively formed during the northward limited subduction process of the lithospheric fault block in South China with oceanic crustal sea areas, and after that under ocean-basin thinning regressive environment in Neoproterozoic. From the perspective of volcanism with sedimentation co-evolution on the relationship between the sedimentation and tectonic analysis, the volcanic activity resulted from oceanic crust subduction may be started from southwest of the study area. This study provides the important evidence for the geotectonic evolution of the Neoproterozoic in the adjacent area between Anhui and Jiangxi from the aspect of the sedimentary stratigraphy. Related Articles | Metrics | Comments（0）

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An Improved Lithological Classification Method for Thermal Infrared Hyperspectral Data Based on Spectral Matching Geoscience    2016, 30 (1): 239-246.   Abstract （9691）      PDF（pc） （11135KB）（18510）       Knowledge map    Save Feature spectral characteristics are the base of hyperspectral remote sensing technology. Based on rock spectral characteristics, for the purpose of classifying lithology by using Thermal Infrared Airborne Hyperspectral Imager (TASI) data, an improved lithological classification algorithm-spectral divergence energy-level matching (SDEM)-is presented in this paper. SDEM can identify tiny differences between any two different spectra. Also, this method takes both spectral band intensity and spectral waveform into account, and can effectively reduce the impact of image noises. Compared with the traditional lithological classification method-high spectral angle mapping (SAM), the improved algorithm can distinguish those similar but different spectra more precisely, and can identify those easily confused lithology. This method is also good at distinguishing the lithology known as “different features with similar spectra”. Using the TASI data of Liuyuan region in Gansu Province, we compared the lithological classification results of SDEM and SAM methods, and found that the SDEM method can identify the lithology that SAM can’t identify or wrongly identified. Based on our field validation work, the classification result by SDEM is more accordant with the actual distribution of rock, and is also more detailed. Related Articles | Metrics | Comments（0）

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Geochemical Characteristics and Tectonic Implication of Basalt in Lower-Middle Jurassic Sewa Formation in Renacuo Area of Gaize, Tibet, China Geoscience    2016, 30 (1): 78-86.   Abstract （9743）      PDF（pc） （34784KB）（18273）       Knowledge map    Save The trachy basalt was discovered in Lower-Middle Jurassic Sewa Formation in Renacuo area of Gaize, Tibet. The contents of SiO2, Al2O3, Na2O and K2O are 45.62%-48.46%, 14.09%-16.51%, 2.68%-4.12%, 1.35%-4.73%, respectively, and the ratio of K2O to Na2O (K2O/Na2O) is 0.34-1.77. The rocks are rich in LREE, and poor in HREE with a weak positive Eu anomaly, as well as an enrichment of elements such as Rb, Ba, U and a depletion of elements like Sr, Yb, Th, Y as a whole. The geochemical characteristics indicate that they are generated in oceanic island environment within the oceanic slab, and that the magma is derived from enriched mantle without or with a little contamination of crust materials and sub-continental lithosphere. The oceanic island rock combination consists of basalt, basaltic gravel and limestone. Combined with the idea that Sewa Formation is seafloor fan sedimentary environment, it can be inferred that the Bangong-cuo-Nujiang ocean was mature oceanic crust in Early-Middle Jurassic. Related Articles | Metrics | Comments（0）

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Formation Mechanism and Characteristics of Non-tectonic Fractures in Shales Geoscience    2016, 30 (1): 155-162.   Abstract （11784）      PDF（pc） （1952KB）（17616）       Knowledge map    Save Non-tectonic cracks are commonly observed in shale and some of them are greatly significant for the evaluation of shale gas accumulation and preservation. On the basis of the previous research and considering the inherent characteristics of shale, a category scheme of shale fractures has been put forward, and the forming mechanisms of the non-tectonic shale cracks has been summarized. According to the core and field observations, we briefly depicted the characteristics of the non-tectonic shale cracks. Among the non-tectonic cracks of shale, those bedding cracks formed in the diagenesis and those overpressure fractures induced by undercompaction or hydrocarbon generation have close relationship with shale gas accumulation and preservation. Related Articles | Metrics | Comments（0） Cited: Baidu(4)

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Dating for Ore-hosting Rock of the Gangcha Gold Deposit in Western Qinling Mountains and Its Geological Significance Geoscience    2016, 30 (1): 36-49.   Abstract （11732）      PDF（pc） （6318KB）（17228）       Knowledge map    Save Gangcha gold deposit is a new medium-sized gold deposit which was found in the northern margin along western segments of Western Qinling Mountains, and it is expected to be a larger scale. There are five ore veins in the deposit, which are limited by the fault zones. The shallow part of host rocks are the volcanic and volcanic clastic rock group. The sets of the volcanic rock groups have been identified as Lower Jurassic Langmusi Formation for a long time before. In fact, those are confirmed as Triassic with the age of (245±2) Ma by zircon U-Pb dating method applied to the tuffs in the group this time. Also, there are two kinds of intruded rocks which are granodiorites and quartz diorites in the deposit, and the both ages are confirmed as (242±2) Ma and (246±3) Ma by zircon U-Pb dating method, respectively. That means that those intrusive bodies and ore-hosting volcanic rock group are same magmatic activity products in Indo-Chinese epoch. Above results limited that the Gangcha gold deposit was formed under magmatic hydrothermal activities after tectonic magmatic activity of Early Triassic period. The study conclusion can provide new facts for advancing gold deposit genesis research and clearing exploration direction. Related Articles | Metrics | Comments（0） Cited: Baidu(6)

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Relationship Between Granophyre and Molybdenum Ore of Wangwu Mining District in North Wuyi Region: Evidences from Zircon U-Pb and Molybdenite Re-Os Dating Geoscience    2016, 30 (1): 59-68.   Abstract （12448）      PDF（pc） （3735KB）（17035）       Knowledge map    Save  The Wangwu Mo-Cu deposit is one that has been explorating and has the potential of large or super-large scale in recent years in North Wuyi region. Based on the study of geological feature, with LA-ICP-MS zircon U-Pb dating, the granophyre vein weighted mean age is (127.5±1.8) Ma(MSWD=1.4).It is shown that the deposit formed in Early Cretaceous Epoch. Using molybdenite Re-Os dating, the isochron age is (153.7±3.2) Ma(MSWD=3.9). It indicates that metallogenesis of Mo occurred in Late Jurassic Epoch. The diagenesis age of granophyre vein is much later than that of Mo deposit, which shows that there is no relationship between them. Comparing the neighbor deposit mineralization feature and analyzing the existed information, it infers that the rock of molybdenum is acidic granite porphyry or biotite granite, which is located in the deep area of southeastern part of the ore district. The major metallogenesis age of Mo is Early-Late Jurassic Epoch (155 Ma±) and Early Cretaceous Epoch(135 Ma±) in North Wuyi area. During this period, the formation of Mo and Cu deposits are related to magmation caused by paleopacific plate subducting. Related Articles | Metrics | Comments（0） Cited: Baidu(5)

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A Preliminary Discussion on Genesis and Ore-forming Fluid Characteristics of the Xinping Gold Deposit in Pingnan County, Guangxi,China Geoscience    2016, 30 (1): 29-35.   Abstract （10204）      PDF（pc） （3564KB）（16981）       Knowledge map    Save  The Xinping gold deposit is located in the Liucen ore field in Dayaoshan polymetallic mineralization belt. The ore bodies, hosted in the sandstone and mudstone of Cambrian Huangdongkou Formation, are related to the Xinping complicated anticline and fracture zone of EW-trending faults.Fluid inclusions in quartz suggest that ore-forming fluids are moderate temperature, low salinity, low density and contain CO2. The cations in fluids are Na+, Ca2+, Mg2+ and K+, while main anion is Cl-. The data of hydrogen and oxygen isotopes indicate that the ore-forming fluids are probably derived from magmatic fluids, and superimposed by metamorphic fluids and meteoric water also involved. The sulfur isotope values in sulfides are narrowly ranged negative not far from zero,which infers that sulfur in ore is a mixture of sulfur from deep source and strata. Our study combined with previous research show that Au has multisources, it mainly sourced from Cambrian strata, but the deep magmatic rocks in the region may also provide some Au. Based on above study, we conclude that the Xinping gold deposit was superimposed mineralization of metamorphism and magmatic-hydrothermal fluids. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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Shale Gas Accumulation Condition and Resource Potential Analysis of Devonian in Dian-Qian-Gui Basin Geoscience    2016, 30 (1): 181-191.   Abstract （9613）      PDF（pc） （5146KB）（16846）       Knowledge map    Save Based on the outcrop observation, profile survey and sample analysis of Devonian dark shale, this paper studied the accumulation condition of Devonian shale gas in Dian-Qian-Gui Basin. The results show that two sets of dark shales of intraplatform depression facies were deposited in Dian-Qian-Gui Basin during the Early to Middle Devonian, and the single layer thickness of Devonian shale is 10-55 m; the accumulative thickness is generally between 100 m and 450 m. The TOC values are mainly in the range of 1.0% to 2.5%, and the organic matter type is Ⅰ-Ⅱ1, and the vitrinite reflectance values indicate high to over mature thermal evolution stages. As an effective reservoir, the porosity and permeability of Devonian shale in Dian-Qian-Gui Basin are similar to those of Jiulaodong Formation in well Wei-201, and various reservoir space types well developed in the shale, and the content of brittle minerals is averagely up to 67%. The gas preservation conditions of southwestern Qiannan Depression and middle-west Guizhong Depression are relatively better because of the relative flat strata, low fault density and erosion thickness, and thrusting and transpressional faults. Overall considering of the dark shale thickness, buried depth, organic matter content, thermal evolution degree and preservation condition, it can be predicted that the favorable intervals of Devonian shale gas are Tangding Formation and Luofu Formation, and the favorable areas mainly distribute in Tian’e-Nandan-Hechi area and Luzhai-Laibin-Heshan-Dahua area of middle Guizhong Depression. By using the analogy method of geological resource abundance, it can be calculated that the geological resources of Devonian shale gas is 0.66×1012 m3 to 1.09×1012 m3 . Related Articles | Metrics | Comments（0）

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3D Metallogenic Prediction Based on Minerogenetic Series: A Case Study in Tongling Mineral District of Anhui Geoscience    2016, 30 (1): 230-238.   Abstract （12027）      PDF（pc） （11334KB）（16596）       Knowledge map    Save In order to quantitatively predict the underlying mineral resources in Tongling mineral district and implement mixed genesis prediction according to the different deposit types, 3D metallogenic prediction based on minerogenic series is imperative. In this paper, we summarized two minerogenic series on the basis of previous studies, including the minerogenic series related to the Yanshanian magmatism and the sedimentary-reformation(metamorphic) minerogenic series. In addition, we summarized the porphyry-skarn-hydrothermal metallogenic model in the study area. Using 3D visualization technology, the 3D digital mine is modeled. After that,by implementing “cubic predicting model”prospecting method, we carried out a three-dimensional metallogenic prediction in the study area, and delineated 14 predicted targets according to the value of information and geolo-gical condition. Our research combines the traditional two-dimensional regional metallogenic prediction methods with advanced visualization technologies successfully, and extends the prediction of mineral resources within the region to three-dimensional space, makes it more conducive to concealed ore delineation work within the region, and also provides a reference for future three-dimensional prediction. Related Articles | Metrics | Comments（0） Cited: Baidu(3)

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3D Seismic Chimney Detection Technology Based on Dip Steering and Its Application on Buir Sag of Hailar Basin YANG Rui-zhao，LI Yang，PANG Hai-ling，ZHAO Zheng-guang，WEN Xiao-long， Geoscience    2013, 27 (1): 223-230.   Abstract （7838）      PDF（pc） （10940KB）（16545）       Knowledge map    Save The gas chimney is a special associated structure formed by the hot fluid flow in the sedimentary basin. As a specific channel for oil and gas migration, the gas chimney is a direct evidence for the existence of shallow reservoirs, and it can also influence hydrocarbon accumulation. These days, many scholars have paid attention to gas chimneys. Based on the research results and thoughts about gas chimneys home and abroad, through the artificial neural network (ANN) which is based on multi-layer perceptron and provided by the brand new seismic solution, i.e.OpendTect, this paper predicts the probability of occurrence for gas chimney, improves the algorithm by using dip steering, presents and applies seismic chimney detection technology based on dip steering. The application of pattern recognition technology in seismic exploration field has been well supplemented and developed. Generally, the 3D seismic chimney detection technology can not only interpret the migration pathway and reason of shallow gas accumulation, but also forecast the development of source rocks. In addition, it is also applicable for distinguishing fault sealing. At last, this process was applied to research the migration pathway and accumulation rules of an oil-bearing block in Buir Sag of Hailar Basin, and the fracture characteristics and types of migration pathways were put forward, then the special configuration relations of oil source, pathway, reservoir and cap rock were summarized, and the corresponding accumulation mode was  established. Related Articles | Metrics | Comments（0） Cited: Baidu(4)

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Geologic Characteristics, Sulfur and Lead Isotope Study of the Shalitashi Lead-zinc Deposit, Southern Tianshan ZHANG Shu, ZHANG ZHao-Chong, HUANG He, ZHANG Dong-Yang, XUE Chun-Ji Geoscience    2010, 24 (5): 856-865.   Abstract （11521）      PDF（pc） （11251KB）（16496）       Knowledge map    Save  The Shalitashi lead-zinc deposit located in Xinjiang Uygur Autonomous Region, NW China is an important lead-zinc deposit in the southern Tianshan polymetallic metallogenic belt. The deposit occurs in the Paleozoic Maidan-Kuokeshale basin as lens, nested and tubular orebodies within the structure fracture zone in the dolomite of the middle Devonian Tuogemaiti Formation. The alteration is weakly developed in the wall rocks. The dominant sulfide minerals in the ore are sphalerite and galena. The ore structures include open-space filling and host-rock replacement. The δ34S values for the sulfide minerals range from -3.6‰ to -12.0‰ which indicates that the reduced sulfur is derived from the seawater sulfate. The 206Pb/204Pb values for sulfides range from 17.8979 to 17.9625，207Pb/204Pb from 15.5981 to 15.6023，208Pb/204Pb from 31.1863 to 38.1971, which implies that the metals were derived from the sediments with high metal contents in the Paleozoic basin. On the basis of the geology and geochemistry characteristics, the Shalitashi leadzinc deposit can be classified into Mississippi valley-type lead-zinc deposit. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(3)

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Fracture Characteristics and Main Controlling Factors of Shales of the Second Member of Kongdian Formation in Cangdong Sag, Huanghua Depression Geoscience    2016, 30 (1): 144-154.   Abstract （9851）      PDF（pc） （7253KB）（16201）       Knowledge map    Save The shale in the second member of Kongdian Formation(Ek2) in Cangdong Sag with large thickness, high values and excellent types of organic abundance, is one of the important intervals for dense petroleum exploration. Based on the detail observation and description of cores, this paper studied lithologic characteristics, fracture types and development characteristics(including length, opening,angle and filling)of shales in Ek2 in Cangdong Sag of Huanghua Depression by the observation of polarizing microscope and fluorescence microscope and laser scanning confocal microscope together with analysis of X-ray diffraction and rock pyrolysis. Furthermore, it analyzed the main controlling factors of fracture development. The shales of Ek2 in Cangdong Sag are mainly composed of felsic, carbonate and clay minerals; the main lithologies are dolomitic shale, silty mudstone, argillaceous dolostone, sandy dolomite and dolomite, etc; the main types of sedimentary structures include massive structure, lamellar structure, laminated structure and lenticular structure, etc.Four sorts of fractures develop in Ek2, i.e. structural fracture, interlayer lamellation crack, vertical-difference load fracture and overpressure-breaking fracture, among which the structural fracture is the most, followed by the interlayer lamellation crack and vertical-difference load fracture, and the overpressure-breaking fracture is the least. The main fillings in fractures are pyrite, analcime, calcite and asphalt. The results show that tectonism, lithology, mineral composition, sedimentary structure, diagenesis and organic matter abundance(TOC) are the main controlling factors for the development of fractures in shales of Ek2 in Cangdong Sag. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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Controlling Factors on the Miocene Channel in Baiyun Sag, Pearl River Mouth Basin Geoscience    2016, 30 (1): 200-208.   Abstract （9494）      PDF（pc） （6258KB）（16028）       Knowledge map    Save During 21-18.5 Ma, 13.8-12.5 Ma and 10.5-8.5 Ma of Miocene, the channels developed in Baiyun Sag. In these three stages, the shape and architecture of the channels were different. During 21-18.5 Ma, the architecture of the channel was simple, the channel extended a long distance and the sediment was deposited in the distal end. In 13.8-12.5 Ma, the channel migrated northward. During the early of 13.8-12.5 Ma, the channel only developed in the south, then developed upstream. The channel in 10.5-8.5 Ma became deeper and narrower, and had the convergent feature. These changes of these channels’ migration and shape feature were due to different controlling factors in these stages. In 21-18.5 Ma, the channel was related to the abundant sediment supply from the shelf margin delta. In 13.8-12.5 Ma, the channel was affected by the significant sea-level decline in 13.8 Ma. In 10.5-8.5 Ma, Dongsha Movement led to the Baiyun Sag uplift and the paleo-topography determined the channel development. The analysis of the controlling factors in different stages provided new information to the research of the channel shape and evolution in each stage. Related Articles | Metrics | Comments（0）

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Simulation of Secondary Hydrocarbon Migration Direction and Prediction of Favorable Zones：An Example from the Second Member of Shahejie Formation of West Slope, Shulu Sag Geoscience    2016, 30 (1): 220-229.   Abstract （9518）      PDF（pc） （1221KB）（16008）       Knowledge map    Save The Shulu sag in the south of Jizhong depression is a typical rift basin. Paleogene formation develops many sets of source-reservoir-cap assemblage, showing good exploration prospects. In order to seek the breakthrough in oil and gas exploration and to clarify the main exploration direction and zones, it’s urgent to deepen the understanding of the secondary hydrocarbon migration of the study area.Taking the Second Member of Shahejie Formation as an example, based on the Arcgis software platform, we could manage the various geological information, such as source kitchen, conducting system, structural features, fluid potential, etc. After then, we simulate the direction of the secondary hydrocarbon migration with fluid potential model under the large scale conditions. The simulation results reveal that the secondary hydrocarbon migration is dominated by nose-structural belt under the restraint of development status of sandbody, and the oil and gas gather in its spine. Finally, four nose-structural belts are selected to be the favorable accumulation zones based on the understanding of simulation results and reservoirforming conditions. Related Articles | Metrics | Comments（0）

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Prospecting Model Based on Ground Hyperspectral Remote Sensing Data of Hongshan Cu-Au Ore Deposit in Xinjiang Geoscience    2016, 30 (3): 577-586.   Abstract （9172）      PDF（pc） （8568KB）（15958）       Knowledge map    Save 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. Related Articles | Metrics | Comments（0）

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Engineering Treatment Effect Evaluation of Large-scale Wading Landslides in Badong County of the Three Gorges Reservoir Area Geoscience    2016, 30 (3): 695-704.   Abstract （9224）      PDF（pc） （3677KB）（15867）       Knowledge map    Save 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. Related Articles | Metrics | Comments（0）

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Alteration and Mineralization of the Guihuachong Porphyry Copper Deposit,Tongling Area, Anhui Province Geoscience    2016, 30 (1): 50-58.   Abstract （9877）      PDF（pc） （4665KB）（15859）       Knowledge map    Save Guihuachong copper deposit is a porphyry copper deposit newly discovered in the Tongling area, Anhui Province. Lithology of host intrusion is granodiorite porphyry, belonging to metaluminous high potassium calc-alkali granite. Wall rock alteration and mineralization study is an important porphyry deposit mineralization study on migration conducted alteration zone rock for geochemical composition of elements, which is based on the analysis of hydrothermal alteration processes. Wall rock alteration is strong in the Guihuachong mining area, and mainly consists of potassic alteration, sericitization, silicification, chloritization, and carbonatization. Alteration zoning is obvious, occurring potassic alteration, sericitization-silicification, and argillation-propylitization belts in outward succession. Major orebodies occur in the sericitization-silicification belt. Alteration and mineralization process of the hydrothermal stage from early to late is divided into four stages, i.e., potassic alteration, sericitization-silicification, quartz-polymetallic sulfide and carbonate stages. Mineralization took place mainly in the quartz-chalcopyrite sulfide stage. The results of migration quality of components in different alteration zones showed that variation of migration quality in the alteration process is high for the major elements except TiO2, MnO, MgO and low for the trace elements except Cr and Cu, and rare earth elements are loss in strong mineralization area and enrichment in the zone of mineralization.low for the rare earth elements. The similar chondrite-normalized REE patterns of the intrusion and the altered rocks from the Guihuachong deposit show close connection of the intrusion with mineralization of the deposit and it is the result of continuous action of magmatic fluids. Related Articles | Metrics | Comments（0）

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Pore Characteristics and the Controlling Factor of the Paleozoic Shale in the South Anhui Geoscience    2016, 30 (1): 172-180.   Abstract （9798）      PDF（pc） （3355KB）（15845）       Knowledge map    Save In order to assess the property of the Paleozoic shale gas reservoir in the south Anhui of Yangtze region, based on the scanning electron microscopy, high pressure mercury-injection, N2 and CO2 gas adsorption methods, the pore characteristics and structures of shale samples from the Paleozoic shales in the South Anhui were studied, and the controlling factors of pores development were discussed. The results show that the porosity and permeability of shale samples are low, and the microscopic pores mainly include inter-grain pores, floe pores, dissolution pores, matrix intergranular pores and organic pores, and the micro-nano scale pores are well developed in these shales. The main pore types in the Paleozoic shales are micropores and mesopores, which account for over 50%. The pore structure of shale is dominated by the parallel-plate pore, cylinder pore and mixed pore, and the average size is about 4.17-12.06 nm. The pore volume and specific surface area increase with the increasing of total organic carbon content (TOC). The porosity of shale reduces as the vitrinite reflectance (Ro) increases. The pore volume increases with the increasing of clay mineral content, but decreases with the increasing of brittle mineral content. Related Articles | Metrics | Comments（0） Cited: Baidu(4)

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Micro/Nano Pore Heterogeneity and Main Controlling Factors of the High-Maturity Longmaxi Formation Shale in Southeastern Chongqing Geoscience    2016, 30 (1): 163-171.   Abstract （9994）      PDF（pc） （2498KB）（15827）       Knowledge map    Save Studying shale pores is the key to understand the mechanism of shale gas occurrence and accumulation. But there is little effective means to quantitatively depict micro/nano pore heterogeneity characteristics of high-maturity shales. This article quantitatively analyzed micro/nano pore heterogeneity and main controlling factors of the high-maturity Longmaxi Formation Shale in southeastern Chongqing through the low pressure N2 adsorption/desorption, high-pressure mercury injection (MIP), and field emission scanning electron microscopy (FE-SEM) experiment together with the use of the fractal dimension. The results show that micro/nano pores develop very well in high-maturity shale. Mesopores are mainly slit-shaped clay interparticle pores and ink-bottle-shaped organic pores. Fractal dimensions of pores between 2.0 nm and 4.5 nm in diameter have an average value of 2.853,4, while fractal dimensions of pores between 4.5 nm and 50.0 nm in diameter have an average value of 2.736,7. The strong heterogeneity is mainly controlled by organic matters. When total organic carbon (TOC) content is less than 0.9%, the pores provided by minerals play dominant role, while the TOC content is larger than 1.7%, organic pores play dominant role. In addition, the increase of clay mineral content will increase the mesopores heterogeneity in a certain extent. Macropores are mainly composed of slit-shaped interparticle pores and a small amount of ink-bottle-shaped organic pores. Fractal dimensions of macropores have an average value of 2.844,1, which show strong heterogeneity, indicating the pore structure is complex. The heterogeneity of macropores is mainly controlled by quartz and carbonate minerals. With the increase of carbonate minerals content, the degree of heterogeneity increases. As organic pores size is relatively small, they have no obvious influence on shale macropore heterogeneity. Related Articles | Metrics | Comments（0） Cited: Baidu(3)

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Main Uranium Mineralization Types and Their Comparison of Geochemical Characteristics in Xiangshan Orefield, Jiangxi Geoscience    2016, 30 (1): 1-16.   Abstract （9826）      PDF（pc） （7803KB）（15822）       Knowledge map    Save Nearly 30 uranium deposits found in Xiangshan orefield of Jiangxi Province, whose uranium mineralization are closely related to hypabyssal or super hypabyssal intrusive rock (subvolcanic rock). Whether porphyry or volcanic rock type is hydrothermal uranium deposits. Analyzing from the metallogenic tectonic characteristics of the hydrothermal deposits in the orefield, there are two kinds of uranium mineralization, namely, cryptoexplosion clastic rock type and alteration rock type, the latter mainly includes hydromica altered rock type and albitization altered rock type. In this paper, by collecting data, combining with the data of relevant topics, a comparative study of geochemical characteristics of various uranium mineralization was carried out. Results show that, the ore grade of cryptoexplosion clastic rock type is higher, and mostly content of U is more than 1%. There is lower SiO2 and Na2O and higher P2O5 , and the ratio of K2O and Na2O is 11.51 on average, and the main associated elements are Hf, Sb, Cu, Pb, Zn, Zr, etc.; K2O/Na2O of hydromica altered rock type is 4.83 on average, and associated elements are W, Pb, Mo, Th, Sb, etc.; K2O/Na2O of albitization altered rock type is 0.19 on average, U has a close relationship with CaO and P2O5, and associated elements are Sr, Zr and Hf, Sc, W, etc. From the albitization altered rock type, to hydromica altered rock type, to the cryptoexplosion clastic rock type, with the increasing of U grade, REE distribution curve appears a regular change from right to left lean. Related Articles | Metrics | Comments（0） Cited: Baidu(2)

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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 Geoscience    2010, 24 (4): 719-726.   Abstract （9473）      PDF（pc） （11556KB）（15818）       Knowledge map    Save  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. Reference | Related Articles | Metrics | Comments（0）

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Characteristics of Fluid Inclusions of the Liangshan Molybdenum Deposit in Central Jiangxi Province and Their Geological Implications Geoscience    2016, 30 (1): 17-28.   Abstract （10050）      PDF（pc） （10824KB）（15612）       Knowledge map    Save The Liangshan molybdenum is one of molybdenum deposits recently discovered in central Jiangxi Province. Its major molybdenite ore bodies are situated within the tectonic fissures of Nanhua system low-grade metamorphic rocks, and molybdenite-quartz veins are the main mineralization types.Fluid inclusions in quartz veins suggest that these inclusions are distributed in groups or scattered stars randomly with long axes of 2-15 microns.There are four types of fluid inclusions, including pure liquid inclusions, gas-rich two-phase inclusions, liquid-rich two-phase inclusions and liquid phase CO2-bearing three-phase inclusions. Liquid-rich two-phase inclusions are the main type of fluid inclusions.The homogenization temperatures range from 136 to 298 ℃, the salinities range from 1.22% to 10.11% NaCleqv and the density range from 0.78 to 0.99 g/cm3, indicating medium-low temperature, low salinity and lower density.The ore-forming pressure is estimated at 13 to 70 MPa, and the depth is about 0.5 to 2.6 km. The inclusions in gas and liquid ingredients all are mainly composed of H2O with a small amount of CO2 and CO in gases by the test of Laser Raman spectroscopy. The hydrogen and oxygen isotopic compositions of the ore-forming fluids show that δD values of the ore-forming fluid are between -61‰ and -57.9‰, and δ18OH2O are between -3.32‰ and -0.52‰, which indicates that the ore-forming fluids were derived from the mixing of magmatic water and meteoric water.The sulfur isotope compositions of ore-forming fluid show that δ34S values of the ore-forming fluid are between -1.8‰  and +1.9‰, which indicates that the sulfur of ore-forming fluid has the characteristics of the sulfur of magma source. Our comprehensive studies suggest that the ore-forming fluid of the Liangshan molybdenum deposit is related with the Yanshannian magmatic activities, the mixing of magma fluid with the meteoric water and later potassic alternation are two main factors to ore-forming material enrichment and precipitation. Therefore, it is proposed that the Liangshan molybdenum deposit is a typical hydrothermal filling quartz vein type deposit related with magmatic activities. Related Articles | Metrics | Comments（0）

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Division of Hydrocarbon Plays and Resources Evaluation in the North Ustyurt Basin, Central Asia Geoscience    2016, 30 (1): 192-199.   Abstract （7873）      PDF（pc） （2320KB）（14118）       Knowledge map    Save Based on the integrated analysis of the basic geological features and oil and gas fields distribution, and cored by reservoirs, seven hydrocarbon plays are divided in the Eocene, Lower Cretaceous, Middle and Lower Jurassic, and Carboniferous reservoirs in the North Ustyurt basin. The undiscovered recoverable petroleum resources of the plays have also been reevaluated by the Monte Carlo method. The result reveals that the total amount of the undiscovered resources is about 2 102 MMboe, of which oil is 1 201 MMbbl and gas is 5 406 Bcf. Geological risks evaluation of key elements including reservoirs, traps, migration and preservation have also been completed. Then, the seven hydrocarbon plays are ranked by the double factors method of resources-risks. According to the classification criterion, there are one Ⅰ-class play, one Ⅱb-class play, two Ⅲ-class plays, two Ⅳa-class plays and one Ⅳc-class play in the North Ustyurt basin. The most favorable exploration objectives in the Mesozoic should be faulted anticlinal traps in the northern slope and on the top of the North Buzachi uplift, where the Paleozoic Bashkirian and Asselian carbonate reservoirs may also have potentials. In addition, it is hopeful to find oil and gas reserves in the local Eocene and Middle Jurassic sandstone and the Carboni-ferous Visean carbonate reservoirs in the eastern basin. Related Articles | Metrics | Comments（0）

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Magnetic Properties of Tree Leaves in Different Environments and the Indication for Atmospheric Environment Pollution Geoscience    2016, 30 (3): 606-613.   Abstract （7509）      PDF（pc） （3546KB）（14092）       Knowledge map    Save 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. Related Articles | Metrics | Comments（0）

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Shallow Super Heavy Oil Reservoir Accumulation Process and Model in LX Oilfield, Liaodong Bay Depression Geoscience    2016, 30 (3): 663-671.   Abstract （7464）      PDF（pc） （5611KB）（13900）       Knowledge map    Save 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. Related Articles | Metrics | Comments（0）

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Diagenesis, Pore Fluid and Controlling Factors of Reservoir Quality in the Basalt Area of Laibei Slope Zone, Huanghekou Sag Geoscience    2016, 30 (1): 209-219.   Abstract （7918）      PDF（pc） （7475KB）（13497）       Knowledge map    Save In order to explore the influence of basalt eruption on reservoir diagenesis in Huanghekou sag, clay mineral, zeolite and trace elements in the Laibei slope zone were studied to make it clear that the pore fluid changes in different formation of Paleogene and then to establish the reservoir diagenesis and pore evolution model in igneous rocks area. In the period of the first and second members of the Shahejie Formation, under the influence of alkaline water medium formed in the small-scale basalt eruption environment and arid-semiarid climate, albitization and carbonate cementation developed universally and dolomite coat grew on grain surface, also we can see the phenomena of quartz dissolution. In the third member of the Dongying Formation, the delta reservoir was influenced by the brine precipitation in dark mudstones of the first member of Shahejie Formation and terrestrial freshwater input, also late rich mafic pore water mixing effect, so the main diagenesis are zeolite dissolution, clay mineral transformation and albitization in alkalescence water medium conditions. In the period of the first and second members of the Dongying Formation, it is characterized by extensive eruption basalt, strong hydrolysis of minerals rich in iron and magnesium element which led to the pore fluid rich in mafic, and the precipitation and dissolution of low silica zeolite. The local precipitate and dissolution of zeolite and “I-shaped” framework associated with basalt eruption is in favour of sandstone pore preservation of Dongying Formation. During the deposition of the first and second members of Shahejie Formation, pectinate dolomite coat which inhibited the quartz overgrowth under the alkaline water medium and the phenomena of quartz dissolution is beneficial to the preservation of the sandstone pore. Related Articles | Metrics | Comments（0）

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Geochemistry of Cretaceous-Palaeocene Detrital Rocks in Simao Basin,  Yunnan Province and Its Geological Significances  Geoscience    2016, 30 (3): 541-554.   Abstract （8277）      PDF（pc） （5465KB）（13175）       Knowledge map    Save 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. Related Articles | Metrics | Comments（0）

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Geochemical Characteristics of Trace Elements of Chencai Group in  Jiangshan–Shaoxing Fault Zone of Zhejiang and Its Relation to Mineralization Geoscience    2016, 30 (3): 493-502.   Abstract （7854）      PDF（pc） （6206KB）（13083）       Knowledge map    Save 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. Related Articles | Metrics | Comments（0）

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Geochronology and Geochemistry of the Wurinitu Granites in Inner Mongolia and Their Geological Implications Geoscience    2016, 30 (3): 528-540.   Abstract （8048）      PDF（pc） （3861KB）（13019）       Knowledge map    Save 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. Related Articles | Metrics | Comments（0） Cited: Baidu(3)

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Sedimentary Characteristics of Fine-grained Alluvial Fan: A Case Study of the Paleogene Baiyanghe Formation in Laojunmiao Structural Belt, Jiuxi Basin Geoscience    2016, 30 (3): 643-654.   Abstract （7754）      PDF（pc） （9722KB）（12997）       Knowledge map    Save 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. Related Articles | Metrics | Comments（0）

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Tracing the Stream Sediment of the Ganjiang River(Nanchang Section)：Constraint from the Detrital Zircon U-Pb Isotope Evidence Geoscience    2016, 30 (3): 514-527.   Abstract （8161）      PDF（pc） （2119KB）（12996）       Knowledge map    Save 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. Related Articles | Metrics | Comments（0）

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Geochemical Characteristics and Its Significance of Reservoir Bitumen of Longwangmiao Formation in Moxi Area, Sichuan Basin Geoscience    2016, 30 (3): 614-626.   Abstract （7964）      PDF（pc） （9583KB）（12908）       Knowledge map    Save 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. Related Articles | Metrics | Comments（0） Cited: Baidu(6)