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Advancement, trend and new challenges in basin geodynamics LI Si-Tian 2015, 22(1): 1-8.  DOI: 10.13745/j.esf.2015.01.001 Abstract ( 1920 )   PDF (1288KB) ( 1910 )   Great advancement has been made in basin geodynamics in the past 20 years. The most important driving force for basin geodynamic research is the great necessity of the hydrocarbon resources for the development of human society. Due to the increased efforts on hydrocarbon exploration and development by both national oil companies and private enterprises, vast data on the architecture and evolution of sedimentary basins have become available for scientific research, especially the large amount of full sets of deep well borehole data with depth of 7000-8000 m, and the high resolution reflection seismic profiles, which have been available for co-operation research groups and scientists in China. Innovative thinking and methods have been suggested on the dynamic processes of basinfill, structural framework and physical mechanism, geodynamic background and petroleum systems, and parts of them are reflected in the research outline of this paper, for instance the routing system and the tectonostratigraphic sequence analysis. While understanding the deep processes of basin dynamics may have been one of the most complicated challenges, using tomography imaging technique and magmaticgeochemistry methods to study plate subduction, mantle flow and lithosphere thinning and rifting, several multidisciplinary groups have achieved comprehensive results for revealing the deep controlling factors of basins and large igneous province in the eastern part of China. Occurring in West China, the geodynamic settings of the superimposed large multicycle basins are completely different from the basins in East China. Tarim Basin and Sichuan Basin are the typical examples. These basins occurred on pre-Cambrian cratons with orogenic belts around them. Strong compaction regimes have impacted these basins during their orogenic periods. The structural deformation created a series of uplifts and depressions, and large oil and gas fields were found to be commonly distributed on the uplifts and their slope area. Systematic age determination of the tectonic events in the orogenic belts has been done by the continental dynamic research groups. The tectonic events and stages during basin evolution can be correlated to that of the orogenic belts.A comprehensive geotectonic process was also developed by the multidisciplinary research groups. Related Articles | Metrics

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Geomorphological evolution, source to sink system and basin analysis LIN Chang-Song, XIA Qiang-Long, SHI He-Sheng, ZHOU Xin-Huai 2015, 22(1): 9-20.  DOI: 10.13745/j.esf.2015.01.002 Abstract ( 2399 )   PDF (2158KB) ( 2045 )    Landscape evolution from mountain to basin and the source to sink system have become a hot topic in the earth science. The growing study field of these themes has been promoting the widely interdisciplinary research and cooperation among geology, geomorphology, atmospheric and oceanographic sciences. This has great influence on the development trend and insight of sedimentary basins. Geomorphologic evolution of an entire basin is the first response to the change of the basin dynamic setting. Distribution of uplift and depression belts, the geomorphology of uplifts and slopes and local geomorphology formed by syndepositional structures comprise the major subjects for analysis of basin geomorphology. Source to sink system from continent to ocean comprises a number of morphological segments including provenance, alluvial and coastal plain or catchment, shelf, slope and basin floor, with various erosional and depositional processes. Characteristics of sediment sources are mainly determined by source rock nature, tectonic setting and climatic condition. Revealing the interplay of tectonics and climate change reconstructing the mountain landscape and generating sediments is a long term task. The continental slope and deep marine basin are final segments in the source to sink system from land to ocean and the relevant studies have been highly regarded. The source to sink system from mountain to lacustrine basin comprises similar morphological segments including catchment (provenance), alluvialcoastal plain, shore and deep lake. The tectonically active terrigenous lacustrine basins are characterized by near and multiple source inputs, tectonic activities, relatively small catchment and various sediment types sensitive to climatic condition. Identification and classification of source to sink systems, including local source to sink systems related to paleouplifts within a basin, according to their source area, valley or channel geometry and depositional systems,are significant for the understanding of basin filling process and sedimentary facies distribution. Seismic geomorphology or sedimentology based on high resolution 3D seismic data provides an effective tool for study of subsurface depositional geomorphology and processes. Related Articles | Metrics

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Accumulation mechanism of large shallow marine turbidite deposits: A case study of gravity flow deposits of the Huangliu Formation in Yinggehai Basin WANG Hua, CHEN Si, GAN Hua-Jun, LIAO Ji-Hua, SUN Ming 2015, 22(1): 21-34.  DOI: 10.13745/j.esf.2015.01.003 Abstract ( 1766 )   PDF (3282KB) ( 1118 )   Large efficient reservoirshallow marine gravity flow deposits of the Huangliu Formation in Yinggehai Basin, south China, which are located at the central Dongfang area, represent the peculiarity in sedimentary features and deposit mechanism. The paleontology study of these gravity flow deposits indicates that the paleowater depth was 40110 m, which implies a shallow shelf environment. The gravity flow features include convolute deformation bedding and contemporaneous deformation structures. The vertical series are mainly Bouma sequence A and AB, which are lack Bouma CDE. The gravity flow deposits show the features of large scale, multiple phases (superposition of turbidite events and combination of vertical series), and sustainable development. The comprehensive genetic mechanism of the large gravity flow deposits that formed in shallow marine environments includes the following features: (1) continuously sources supply, (2) large-scale regression during the syndepositional period and (3) episodic dynamic and differential subsidence of shelf paleogeomorphology. The gravity flow deposits on the shallow marine shelf are the combined controlling results of source supply, tectonic activity, and relative sea level change, which represent high coordinated relationship between these influence factors. Therefore, this study will focus on the microscopic and macroscopic features, accumulation controlling factors, and particular mechanism of the shallow marine gravity flow deposits based on the research method and technique of tectonicsequence stratigraphy, sedimentology, and geophysics exploration. Intensive study of these shallow marine gravity flow deposits provides important theoretical value and practical significance for the theoretical research of large gravity flow deposits in the shallow marine environment, and also provides reference for the frontier exploration of oil and gas. Related Articles | Metrics

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DevonianCarboniferous tectonic evolution of continental margins in northern Tarim block, Northwest China: Constrained by basinfill sequences and provenance systems LI Zhong, GAO Jian, GUO Chun-Tao, XU Jian-Qiang 2015, 22(1): 35-52.  DOI: 10.13745/j.esf.2015.01.004 Abstract ( 1743 )   PDF (3108KB) ( 1693 )    Active and varied sedimentation frequently occurred in continental margin area during oceancontinent or basinrange transformation, a complex process with limited knowledge so far.Based on stratigraphic correlation between continents and orogens, two more complete DevonianCarboniferous profiles, located between the northern margin of Tarim block and South Tianshan (TST belt), are investigated and studied focusing on basinfilling and depositional sequences. Alkaline basalt, radiolarian chert and turbidite were developed from the Devonian to the Early Visean Phase of the Early Carboniferous. However, relatively shallow carbonate and terrigenous clastic rocks, with mixed sedimentary strata, distinctly deposited after the Late Visean Phase, indicating the occurrence of oceancontinent transformation.Further research focuses on 19 detrital heavy mineral samples and 12 detrital zircon (U-Pb and Hf) geochronological ones.Combined with sandstone framework grain components, the provenance and tectonic evolution implications are synthetically analyzed. From the Devonian to the Early Visean Phase of the Early Carboniferous, unstable and varied detrital assemblages, with some detrital zircons approximately similar to their strata age, occurred in the eastern section of TST belt, showing chaotic deposition and relatively short south-north sourcesink (provenancedeposition) systems limited in active continental margin.However, more mature sandstone components, with a lot of detrital zircons bearing basement ages of Tarim continental block, were developed in the western section of TST belt, which is evident deposition attributes related to passive continental margin. From the Late Visean Phase of the Early Carboniferous to the Late Carboniferous, relatively higher mature sandstone components, with an amount of detrital zircons bearing the basement ages of Tarim continental block and some zircons with age of 390460 Ma showing typical positive εHf(t) values, deposited in the eastern section of TST belt.It mainly attributes to the complex orogen provenance type and middle-short sourcesink systems, probably reflecting deposition in residual sea. At the same stage, even higher mature sandstones, with dominant detrital zircons bearing basement ages of Tarim continental block, accumulated in the western section of TST belt, probably showing deposition in failed ocean or residual sea, characterized by relatively long sourcesink systems across continental margin and interior. No clear orogeny evidences were found from depositional records in the study area till the Late Carboniferous Epoch, though the South Tianshan ocean closed after the Visean Phase of the Early Carboniferous. Therefore, evident divergence of continental margin tectonic and relative basin system evolution existed between the eastern and western sections of TST belt, which was a response to the complexity of continental margin rifting, archipelagic ocean closure and continent (micro-continent) convergence in the Central Asia. Related Articles | Metrics

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The analysis of the relationship between provenance and tectonic setting of the Middle-Upper Ordovician in the northeastern Tarim CHEN Qiang-Lu, ZHAO Xin, CHU Cheng-Lin, SHI Zheng, YANG Xin 2015, 22(1): 53-66.  DOI: 10.13745/j.esf.2015.01.005 Abstract ( 1662 )   PDF (2474KB) ( 1112 )   Based on sedimentary structure and sampling of the Middle-Upper Ordovician in Queerqueke, Yuanbaoshan and Nanyaerdang profiles in Quruqtagh area, the provenance and tectonic setting of the MiddleUpper Ordovician are studied, combined with the well and seismic data. The Queerquek Formation in the MiddleUpper Ordovician is thought to be the flysch deposition. According to the sedimentary structure, heavy mineral assemblage, mineralogical maturity, cathode luminescence and characteristics of major elements, trace elements and rare earth elements, the tectonic setting of the MiddleUpper Ordovician is the continental island arc and active continental margin. In the early sedimentary stage, the provenance of Queerquek Formation came from the north paleoland mass, which was composed of granitoid and metamorphic rocks; in the middlelate sedimentary stage, some pyroclastic from the Altyn orogenic belt turned to be a new provenance. The analysis of the provenance of the MiddleUpper Ordovician provides a basis for studying the relationship between the tectonic uplift and the sedimentary filling, and for predicting the distribution of tight sandstone of the Middle-Late Ordovician. Related Articles | Metrics

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Sedimentary filling configuration of YantingTongnan trough under the background of intracratonic rift in Later Permain, Sichuan Basin LI Qiu-Fen, MIAO Shun-De, WANG Tong-Shan, JIANG Qing-Chun, HONG Ze-Cheng, LI Jun, XIE Fen, YIN Ji-Feng, GU Zhi-Dong 2015, 22(1): 67-76.  DOI: 10.13745/j.esf.2015.01.006 Abstract ( 1851 )   PDF (2530KB) ( 1040 )   Previous research shows that Sichuan Basin underwent intracratonic rift and basement fault activities in the Late Permian, developing a paleogeographic framework of “three uplifts and three depressions” under the background of the regional large ramp, including ExiChengkou trough, KaijiangLiangping trough and YantingTongnan trough. Based on geological background and tectonic dynamics analysis and using data of drillings, outcrops and seismos, YantingTongnan trough has been researched in Central Sichuan Basin in our study, which extends in NWSE nearly paralleling to KaijiangLiangping trough, opening to the sea northwestward, and gradually becoming shallower to the east platform and conneted to ExiChengkou trough. According to the comprehensive analysis of geology and seismism, sedimentary configuration of YantingTongnan trough has been discussed, which mainly filled with fine grained sediment, and platform margin reef belt distributes around the trough. Organic banks distribute on the west margin of the trough and reefs on the east margin of the trough. The formation, evolution, filling and extinction processes of the YantingTongnan trough was controlled by the expansion of Mianlüe ancient ocean; in the extensional tectonic environment, due to Emei Taphrogenesis, the NW basement faulting inside Sichuan Basin caused tensoshear activities and thus resulted in tectonic differential settlement of cratonic basin and a series of uplifts and troughs. Related Articles | Metrics

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Difference of tectonic evolution of continental marginal basins of South China Sea and relationship with SCS spreading XIE Xi-Nong, REN Jian-Ye, WANG Zhen-Feng, LI Xu-Shen, LEI Chao 2015, 22(1): 77-87.  DOI: 10.13745/j.esf.2015.01.007 Abstract ( 2050 )   PDF (2069KB) ( 1450 )   Continental marginal basins in southern and northern South China Sea (SCS) show not only distinct tectonic regimes, including divergence, transformextensional and flexuralextensional complex types, but also have different tectonic evolutionary stages, due to different boundary conditions. Discordance between the breakup of continental margins and South China Sea spreading processes are presented. The research results indicate that a series of rifting basins are developed in the southern and northern continental margins during the SCS spreading, which are resulted in the formation of main rifting stage. However, the time of breakup unconformity is quite different. The rifting terminates on the age of 23 Ma or 21 Ma in the northern margins of the SCS, while did not terminate until the age of 15.5 Ma in the southern margins of the SCS. Those features indicate that the age of the breakup unconformity in the continental margins show a clear shift southward, which means that in the northern SCS is earlier than in the southern SCS. There are clear differences in tectonic regimes after the termination of the SCS spreading. Extension is dominated in the northern SCS and rapid subsidence episode is present since the Late Miocene, but compress regimes are present in the southern SCS, where the age and intension of compressive stress in the Zengmu basin are earlier and stronger than in the Beikang and Nanweixi basins. Transformation and distinct tectonic evolution in the southern and northern continental marginal basins indicate the shift of the SCS spreading, and are used to suggest the shift southward in the different ending times of the spreading processes for the three oceanic subbasins of the SCS. Therefore, differences in formation and evolution of continental marginal basins in the northern and southern SCS provide a helpful evidence for the reasonable interpretation for the spreading processes of the SCS. Related Articles | Metrics

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Discrepancy tectonic evolution and petroleum exploration in China offshore Cenozoic basins ZHU Wei-Lin, WU Jing-Fu, ZHANG Gong-Cheng, REN Jian-Ye, ZHAO Zhi-Gang, WU Ke-Qiang, ZHONG Jie, LIU Shi-Xiang 2015, 22(1): 88-101.  DOI: 10.13745/j.esf.2015.01.008 Abstract ( 1794 )   PDF (2724KB) ( 1346 )   As China offshore area lies rightly in the convergence area where Eurasian, IndianAustralian and the Pacific Ocean plates meet, the generation and evolution of basins in this area is under controls of the interaction between ocean and continental plates, which means the regional tectonic setting plays a significant role during basin formation and evolution. Under the impact and control of this special tectonic setting, China offshore basins have significant segmentation and discrepancy evolutional features. Those basins from the Bohai Bay Basin to the South Yellow Sea, via the North Yellow Sea, are belonging to the intracontinental rift basin; the East China Sea basins are the retroarc rift basins in the active continental margin; the Pearl River Mouth Basin and Qiongdongnan Basin belong to passive continental margin basins; the Yinggehai Basin is a transform continental margin basin. As a result, the oil and gas distribution is also characterized by segmentation and partition. Intracontinental basins from Bohai Bay to South Yellow Sea are mainly oilproducing; the retroarc basins of East China Sea are primarily producing gas; the northern part of the continental margin of northern South China Sea is basically oil and the southern part is mainly gas; the transform Yinggehai basin produces gas as priority. The future oil exploration fields of China offshore area would be on the Bohai Bay Basin, the northern part of Pearl River Mouth Basin and Beibu Gulf Basin; while the gas exploration areas should be mainly focused on the East China Sea, deep water area of northern South China Sea and Yinggehai Basin. Related Articles | Metrics

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Ocean and continent transition in passive continental margins and analysis of lithospheric extension and breakup process: Implication for research of the deepwater basins in the continental margins of South China Sea REN Jian-Ye-, PANG Xiong, LEI Chao, YUAN Li-Zhong, LIU Jun, YANG Lin-Long 2015, 22(1): 102-114.  DOI: 10.13745/j.esf.2015.01.009 Abstract ( 1907 )   PDF (2293KB) ( 1274 )   As an important transition domain between the last identifiable extended continent crust and the first true oceanic crust, the oceancontinent transition (OCT) zone preserved a wealth of information on the processes of lithospheric extension and breakup. In this paper, considering OCT as a key to understanding the mechanism of the lithospheric extension and breakup, we try to show the geological nature of the OCT, and its geological and geophysical identification based on an integrated analysis of a rich subsurface data, including borehole data and newly released geological and geophysical data collected by marine geological survey and hydrocarbon exploration and development. We are also to elucidate the continental lithosphere configuration and its overlying sedimentary basins tectonostratigraphic framework in the different tectonic units on the continental margin. It is noteworthy that we will compare the structures, major tectonic boundaries and tectonic sequences in the sediment fillings of the basins, which will explore the information during the processes of the continental margin extension, exhumation, breakup and oceanic spreading. In addition, we will study the largescale detachment faults and their controls on the lithospheric thinning and continental mantle exhumation. We will investigate where the lithosphere of continent margin concentrated, and how the deformtion migrated and superimposed, and further construct the model of lithospheric extension and breakup. OCT is the area where the lithospheric deformation and final breakup occurred. Therefore, Our research will better improve our understanding of the birth of the oceanic crust and symmetric conjugate structures in the South China Sea, and has a great significance for economic exploration(hydrocarbon) in the deepwater/ultradeepwater area of South China Sea. Related Articles | Metrics

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The records and its dynamic genesis discussion of tectonic movement during the Late Sinian and the Early Cambrian of Sichuan Basin XING Feng-Cun, HOU Ming-Cai, LIN Liang-Biao, XU Sheng-Lin, HU Hua-Rui 2015, 22(1): 115-125.  DOI: 10.13745/j.esf.2015.01.010 Abstract ( 2084 )   PDF (2562KB) ( 1391 )   A supergiant oilgas field with geological reserves of more than one trillion cubic meters, located in the middle area of Sichuan Basin, has been found in the CambrianSinian strata. Previous studies revealed the importance of persistent MoxiLongnüsi paleouplift. The existence of DeyangAnyue intracratonic sag (aulacogen sag) and its important in controlling rich hydrocarbon generation depression was recognized. Nevertheless, the development, evolution and formation of the dynamic mechanism need to be further researched and investigated. Based on a large number of field work and analysis, combined with the existing underground data such as drilling and seismic data, focused on midwest area of Sichuan Basin, the structuresedimentary records during the Late Sinian to the Early Cambrian were analysed and discussed. The corresponding Ⅰ, Ⅱ, Ⅲ episodes of Tongwan tectonization correspond to the boundary between the Member 3 and 2 of Dengying Formation, Maidiping Formation and Dengying Formation, Qiongzhusi Formation and Maidiping Formation, and they includ the strara of the Member 3 of Dengying Formation, Maidiping Formation and Qiongzhusi Formation. Among those, typical gravity flow slump deposits and volcanic activity records such as tuff were found in the first episode of Tongwan tectonization. Superposed characteristics of structure interface between the second and third episodes of Tongwan tectonization occurred in most areas of Sichuan Basin and formed a regional unconformity. Typical debris flow deposits and supergene karst response can be found in southern region of Sichuan Basin. The evolution process of three episodic tectonization in general has characteristics of upliftingsubsiding, then subsidence filling. The uplift area and subsidnce area have a certain superimposition, and relative deep shelf area(previous intracratonic sag or rift trough) was formed during the sedimentary period of the Member 3 of Dengying Formation and the Maidiping Formation in the western margin of Sichuan Basin. It is the central deposition region during the sedimentary period of Doushantuo Formation and the Member 1 and 2 of Dengying Formation. The study suggested that the relative deep water area was continuingly inherited from the basement, and it has characteristics of episodic activity enhancement during the sedimentary period from the Member 3 of Dengying Formation to Qiongzhusi Formation. Finally, the dynamic genesis was discussed. Related Articles | Metrics

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Deep structure of major basins in Western China and implications for basin formation and evolution SONG Xiao-Dong, LI Jiang-Tao, BAO Hue-Wei, LI Si-Tian, WANG Liang-Shu, REN Jian-Ye 2015, 22(1): 126-136.  DOI: 10.13745/j.esf.2015.01.011 Abstract ( 2170 )   PDF (2307KB) ( 2441 )   Seismic tomography is an important tool for studying the structure and dynamics of the Earths interior. We gave a brief introduction to the main methods used for seismic tomography of the lithosphere. Relative to seismic exploration with controlled sources, seismic tomography with passive natural sources is an effective and economic method for imaging the deep structure of the basement and the surrounding of a sedimentary basin. Weve recently obtained a highresolution Swave velocity model of the lithosphere in China from surfacewave tomography, which combines data from earthquakes and ambient noise correlations with much improved ray coverage. Our results show major common features of the three basins (Tarim, Qaidam, and Sichuan) surrounding the Tibetan Plateau in the western China: (1) the upper crust of the basins shows slow velocities corresponding to the thick sedimentary layers; (2) the midcrust, lower crust, and in particular, the uppermost mantle show faster speeds than the surrounding mountains; (3) the basins have thinner crust than the surrounding mountains and the Moho depth change is rapid. Significant lateral structure also exists within the basins, in particular, the Tarim and Sichuan Basins. The eastwest paleosuture in the central part of the Tarim is clearly visible in the crustal and mantle lithosphere velocities and in Moho depth variation. These results suggest that regional compression may involve the entire lithosphere. We propose a mechanical model (called compressional upliftsubsidence model) for the formation of the basins: under the regional compressional stress, the weaker lithosphere blocks surrounding the basins are thickened and uplifted, and the stronger basin blocks subside relative to the surrounding mountains under the lithosphere isostacy, forming an intraorogenic basin. The compressional stress may have also deformed the giant Tarim and Sichuan Basins and created folds in a lithosphere scale. In the long geologic history of the formation of the major basins in the Western China, the lithospherescale compression from the Cenozoic IndiaEurasian collision and several orogenic episodes since the NeoProterozoic may have played a determining role in the formation and evolution of the basins. Related Articles | Metrics

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Late Mesozoic tectonomagmatic activities and prototype basin restoration in Eastern Shandong Province, China ZHOU Yao-Qi, ZHANG Zhen-Kai, LIANG Wen-Dong, LI Su, YUE Hui-Wen 2015, 22(1): 137-156.  DOI: 10.13745/j.esf.2015.01.012 Abstract ( 1778 )   PDF (4358KB) ( 1098 )   A set of sedimentary strata represented by terrigenous clastic rocks, volcaniclastic rocks and volcanic lava are developed among the metamorphic rocks and Yanshan granites in Eastern Shandong, which leave fierce debates on their ages, sedimentary characteristics and significance of the regional tectonics. This paper presents the characteristics of the strata around the outcrops of Lingshandao, Tangdaowan, Dashangzhuang in Wulian, Shandongtou in Zhucheng, Yakou in Mountain Laoshan. Samples from the Yakou of Laoshan Mountain and Laohuizui of Lingshan Island were dated using zircon LAICPMS method, yielding two weighted mean 206Pb/238U ages of 118.9±3.3 Ma and 119.2±2.2 Ma which are coincident with the beginning of the volcanism of the Qingshan stage in the Jiaolai Basin. There was a largescale rift basin extending in NE direction developed in the offshore areas of Eastern Shandong Province during the Late Mesozoic, inferred by the sedimentary structures. This basin is characterized by alternating uplifts and depressions. Late Mesozoic tectonomagmatic activities and the evolution of regional tectonic stress field were systematically summarized, and it shows a fine comparability between the rift basin and Jiaolai Basin. These two basins may be a whole in the Laiyang stage and were separated by the volcanic arc exposing along the WulianQingdao fault zone and Mouji fault zone in the Qingshan stage. Finally, this offshore prototype basin of the Late Mesozoic was restored based on the above analysis. Related Articles | Metrics

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Characteristics of Meso-Cenozoic thermal regimes in typical eastern and western sedimentary basins of China QIU Nan-Sheng, ZUO Yin-Hui, CHANG Jian, XU Wei, ZHU Chuan-Qing 2015, 22(1): 157-168.  DOI: 10.13745/j.esf.2015.01.013 Abstract ( 1647 )   PDF (1995KB) ( 1126 )   The thermal regime and thermal history of sedimentary basins play an important role in basin dynamics and hydrocarbon accumulation. The sedimentary basins in the western and eastern China underwent different tectonic background and dynamic mechanism, which resulted in the differentials of their thermal regimes. In this paper, the Meso-Cenozoic thermal regimes of the Bohai Bay Basin in the eastern China and Tarim Basin in the western China were studied based on the thermal history, “thermal” lithosphere and lithospheric thermal structure, and the results show that the thermal regimes in these two basins underwent different evolution since the Mesozoic. The heat flow of the Bohai Bay Basin underwent two peak evolution phases occurred in the Early Cretaceous to the early Late Cretaceous (K1K12) and the Eocene-Oligocene (E2E3) respectively, while the heat flow in the Tarim Basin gradually decreased from the Mesozoic to the Cenozoic. Two rapidly thinning processes of the “thermal” lithosphere in the Bohai Bay Basin occurred in the Late Early Cretaceous and the Paleocene, and its minimum thickness was only 4355 km in the Paleocene. However, the thickness of the “thermal” lithosphere in the Tarim Basin increased slowly in the Mesozoic and then rapidly since the Paleocene. The ratio of crust to mantle heat flow revealed that the lithospheric thermal structure of the Bohai Bay Basin was divided into two phases: “cold mantle and hot crust” type during the Triassic-Jurassic but “hot mantle and cold crust” type since the Cretaceous, while that of the Tarim Basin always stayed in the “hot mantle and cold crust” phase and then transferred to “cold mantle and hot crust” phase since the end of the Neocene. The differences of the lithoshperic thermal structures and thermal conditions between these two basins were closely related to the thermalrheological structure and deformation of the lithosphere. The research on the thermal history and lithospheric thermal structure of the sedimentary basins could effectively reveal the thermal regime in the deep of the sedimentary basins and provide scientific reference for studying the basin dynamic mechanism during the MesoCenozoic. Related Articles | Metrics

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Mechanisms of natural gas accumulation and leakage in the overpressured sequences in the Yinggehai and Qiongdongnan basins, offshore South China Sea HAO Fang, LIU Jian-Zhang, ZOU Hua-Yao, LI Peng-Peng 2015, 22(1): 169-180.  DOI: 10.13745/j.esf.2015.01.014 Abstract ( 1819 )   PDF (1573KB) ( 895 )   This article discusses the specific characteristics and mechanisms of natural gas accumulation and leakage in overpressured sequences. Based on the pressure, stress regimes and the petroleumbearing properties, three types of overpressured reservoirs (filled, underfilled, unfilled or drained) are recognized. The charging history and gasbearing properties of all drilled traps in the Yinggehai and Qiongdongnan basins are closely related to overpressure. The newly discovered DF13-1 gas field is a filled overpressured gas reservoir, whereas the YA21-1 structure represents unfilled or drained overpressured trap with waterphase pressure close to the fracture pressure of the top seal. The accumulation or leakage of natural gas in overpressured traps is controlled by the minimum horizontal stress, the intensities of waterphase pressure relative to seal fracture pressure, and the geomechanical properties of top seals. In the Yinggehai and Qiongdongnan basins, fault and diapercontrolled overpressured traps may contain relatively short gas columns compared to lithologic traps with similar burial depth and waterphase excess pressure. The depth to the crest of lithologic traps played an important role in determining the pressure state and gasbearing properties of the reservoirs. Effective prediction of the pressure and stress combined with the analysis of the geomechanical properties of the seals is an important way to reduce exploration risk. Related Articles | Metrics

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Theory of petroleum accumulation in syncline and its significance to petroleum geology WU He-Yong, WANG Yue-Wen, LIANG Xiao-Dong, YUN Jian-Bing 2015, 22(1): 181-188.  DOI: 10.13745/j.esf.2015.01.015 Abstract ( 1813 )   PDF (1286KB) ( 1010 )    The conventional petroleum geology theory is suitable for the reservoirs with high permeability and fluid flows obeying Darcy law with buoyancy effect mechanism, and oil and gas are situated at the high position of structure and sand body, and they are always structural reservoirs. But this theory does not apply to the reservoirs with low and ultralow permeability or tight reservoirs where fluid flows obey non-Darcy law, and oil and gas cannot be separated by gravitation. On the condition of overpressure expulsion, flow primarily migrates as episodic expulsion manner, the oil droplets gradually deform and pass through the pore throats as nonDarcy flow. This low speed migration must lead to the stagnant mechanism that oil stagnates and accumulates in the lower area and form continuous reservoirs. This stagnation accumulation reservoirs will cause the phenomenon that oil accumulates in anticline area, or oil accumulates at low position of slope but water accumulates at high position, which is the oil-gas inversion. The stagnation accumulation reservoirs which have no structure, no lithology traps, no unified temperaturepressure systems and oilwater contacts have changed the traditional trap exploration method, expanded the concept of reservoir, and formed the fundamental theory for the research field such as reservoirs with low and ultralow permeability and unconventional and tight reservoirs. Theory of petroleum accumulation in syncline is an important supplement to traditional petroleum geology. This theory expands the exploration area, changes the exploration target from high position of structure to low position, extremely increases the petroleum source and is regarded as important guiding principle for the petroleum exploration and development. Related Articles | Metrics

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Sedimentarytectonic setting of the depositiontype uranium deposits forming in the PaleoAsian tectonic domain, North China. JIAO Yang-Quan, WU Li-Qun, PANG Yun-Biao, RONG Hui, JI Dong-Min, MIAO Ai-Sheng, LI Hong-Liang 2015, 22(1): 189-205.  DOI: 10.13745/j.esf.2015.01.016 Abstract ( 1956 )   PDF (4138KB) ( 1344 )    Exploration over the past two decades indicates that the PaleoAsian orogenic belts across north China and MesozoicCenozoic continental basins around their both sides are the most important metallogenic tectonic domain for the formation of the depositiontype uranium deposits in China. The Paleo-Asian orogenic belts are essential uraniumrich geological bodies. The uranium delivery system depends on the transportation of the surface drainage restricted by basinmountain coupling mechanics. Mudstonetype uranium deposits were fed by the single uranium source, whereas sandstonetype uranium deposits were fed by the double uranium source, and the regenerated uranium source originated from uranium reservoirs is quite important. Slack and sustained geotectonic background during the dormant period of the trustorogeny process and the postfault thermal subsidence is a period favorable to the formation of depositionalmetallogenic environment. Mudstonetype uranium deposits need synsedimentary sustained tectonic setting.Sandstonetype uranium deposits were formed under not only the synsedimentary sustained tectonic setting, but also the tiptilting tectonic setting during the mineralization period. Some sandstonetype uranium deposits were obviously affected by the tectonic setting after mineralization. Survey indicates that the efficiency of interlayer oxidation is the highest, and the transported flux of uranium is the largest, and the large even super large uranium deposits tend to be formed when the mineralcharged flow field during the mineralization period was consistent to the synsedimentary palaeocurrent. Synsedimentary palaeoclimate is a significant geologic factor affecting the development of uranium reservoirs and interlayer oxidation zone, which constrained not only the architecture and size of uranium reservoirs, but also the types of reductive media inside and outside uranium reservoirs and their spatial distribution. The morphology and architecture of uranium reservoirs restricted the direction and track of interlayer oxidation zone, whereas the reductive media inside and outside uranium reservoirs controlled the advancing mileage and location of frontal line of the interlayer oxidation zone. Uranium mineralization is related to the redox geochemical barrier. This study shows that the MesozoicCenozoic basins around the PaleoAsian orogenic belts are primary prospective area for depositiontype uranium deposits. Based on the indepth analysis of the regional tectonic framework and rechargerunoffdischarge system of the mineralcharged flow field, the prospecting target can be delineated and evaluated according to the synsedimentary palaeoclimate, types of reductive media and their spatial distribution of uraniumbearing series in the target basin. Related Articles | Metrics

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Dynamics of diagenesis and prediction of diagenetic facies under abnormally low pressure in the Southern Liaohe West Sag MENG Yuan-Lin, WU Lin, SUN Hong-Bin, WU Chen-Liang, HU An-Wen, ZHANG Lei, ZHAO Zi-Tong, SHI Li-Dong, XU Cheng, LI Chen 2015, 22(1): 206-214.  DOI: 10.13745/j.esf.2015.01.017 Abstract ( 1803 )   PDF (1502KB) ( 859 )   Lowabnormally low pressure in the sandstones and overpressure in the mudstones were developed in the Paleocene of the Southern Liaohe West Sag. The diagenesis were accelerated by the low pressure in the sandstones and retarded by the overpressure in the mudstones. A new numerical model was built, which could be used to simulate the diagenetic history and predict diagenetic stages and facies under abnormal pressure systems. The results show that the synrift stage is characterized by intensive fault activities, high heat flow and high diagenesis rate, contrasting to the weak tectonic activity, low heat flow and low diagenesis rate of postrift stage. The part of Shahejie Formation at the deep sag has entered the phase B of middle diagenetic stage to late diagenetic stage, forming tight reservoirs, while part of Shahejie Formation at the slope area is mainly at early diagenetic stage to phase A of middle diagenetic stage, forming conventional reservoirs. Related Articles | Metrics

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The progress and application of reservoir geochemistry in hydrocarbon exploration: An example from the Fushan Depression, Beibuwan Basin, South China Sea LI Mei-DJun, WANG Tie-Guan 2015, 22(1): 215-222.  DOI: 10.13745/j.esf.2015.01.018 Abstract ( 1682 )   PDF (1345KB) ( 749 )   Reservoir geochemistry can be applied to trace the oil migration orientations, reservoir charging pathways and to predict the location of potential source kitchens and “satellite” reservoirs. The tracing indicators related to carbazoles and benzocarbazoles have been widely and successfully applied in hydrocarbon exploration. More and more studies indicate that the sulfur and oxygen heterocyclic aromatic compounds such as dibenzothiophenes and dibenzofurans have been proved to be effective geochemical molecular markers for tracing oil migration orientations and charging pathways. The organic geochemistry study of the Fushan Depression (one of major depressions in the Beibuwan Basin, South China Sea) in the year of 2004 indicated that the discovered accumulations in the Huachang oil and gas field were mainly migrated and charged from the northeast to the southwest along the Huachang Sub-uplift. It can be predicted that the oils in the Huachang Sub-uplift should be sourced from the source kitchen at the Bailian Sag. The Huadong and Bailian zones located on the east of the Huachang Sub-uplift should be the most favorable prospecting zones, which have been proved by the hydrocarbon exploration discoveries afterwards and the latest reservoir geochemistry study. The isopleth maps of geochemical parameters can be used not only to determine the oil migration orientations, but also to predict the favorable charging pathways. Related Articles | Metrics

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Tectonic evolution and metallogenic ore-controlling tectonic characteristics of Hadamengou gold deposit in Inner Mongolia NIU Shu-Yin, SUN Ai-Qun, MA Bao-Jun, JIANG Si-Hong, NIE Feng-Jun, ZHANG Jian-Zhen, WANG Bao-De, XIA Dong 2015, 22(1): 223-237.  DOI: 10.13745/j.esf.2015.01.019 Abstract ( 1619 )   PDF (2756KB) ( 974 )   The Hadamengou Gold Deposit in Inner Mongolia is so far the largest gold deposit, with superlarge scale. The gold mineralization has no definite selectivity on lithology, however，it is mainly controlled by fold and fault structures. Ore-forming fluids are mainly originated from the deep source, and are accumulated within the favorable zones of tectonic expansion forming the ore-deposit. Research shows that, the mechanical property of the structural deformation in this area had been evolved from plastic to brittle since the beginning, and the scale of deformation is from small to large. Folding and shearing deformations were formed simultaneously or alternatively during the tectonism. There are four periods (or times) of intensive folding and shearing in this area, and the main ore-forming and orecontrolling structures are formed during these periods. During the first period, the rocks showed strong rheological property. So the foldings developed are characterized by low amplitude and small scale plastic rheomorphic folds. They are thickened in hinge zone and thinned in the limbs, even appeared a series of ptygmatic folds, and small scale ductile shear zones are developed. Second period of deformation formed the major regional fold which takes the Wulashan main peak antiform as a backbone forming east-west trending anticlinoria and synclinoria, and developing a series of brittle ductile shear zones in the overturned limbs of the major folds, they constitute the regional tectonically weak zones. In the third period developed the crossover superimposed fold, which makes the nearly E-W-trending folds turned to be North-South snake-like bending, accompanying with low greenschist facies ductile-brittle shear zone, which provides the favorable space for the occurrence of ores formed by penetration and accumulation of the deep sourced oreforming fluids and is the main oreforming and ore-controlling structure. The fourth stages of tectonic deformation is mainly of regional uplift, together with the bending of the earlier folds the gold ore bodies formed in the depth are uplifted to the shallower part, and makes them easier to be found and exploited. In the present paper on the basis of research on the metallogenic and ore-controlling structures, the metallogeny of ore-deposits is discussed and the perspective of ore-prospecting is put forward. Related Articles | Metrics

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Geochemical characteristics of the volcanics from the Southern Jueluotage Area and their constraints on the tectonic evolution of Paleo-Asian Ocean MUHETAER·Za-Ri, NIJIATI·A-Bu-Du-Xun, WU Zhao-Ning 2015, 22(1): 238-250.  DOI: 10.13745/j.esf.2015.01.020 Abstract ( 1594 )   PDF (1739KB) ( 1022 )   This paper deals with the geochemical data including major and trace elements and Sr-Nd isotopes of the volcanics from Yamansu Formation and Tugut Bulak Formation, occurring along the southern Juoluotage tectonic belt. Yamansu felsic lava is mainly of lowK tholeiite series, Mg# changes from 49 to 51. The values of ISr range from 0.70642 to 0.70768 and εNd(t) from 3.28 to 5.49. It is relatively enriched in LREEs and LILEs, and depleted in HREE and HFSE with moderate Eu anomalies(δEu=0.620.65). All these geochemical characteristics suggest that the formation of the Yamansu felsic lava is probably related to differentiation process of mantlederived mafic magma. The andesites from the Tugut Bulak Formation are mainly of calc-alkaline and high K calcalkaline series, Mg# changes from 53 to 57. Geochemical studies on trace elements demonstrate the total LREE enrichment and relative HREE depletion with slight negative Eu anomalies(δEu=0.630.84). The primordial mantlenormalized trace element patterns are characterized by LILE enrichment and HFSE depletion. SrNd isotopic data show that the ISr values range from 0.70371 to 0.70498, while εNd(t) changes from 6.48 to 6.83, indicating that the parent magma is originated from a juvenile lithospheric mantle wedge that was previously metasomatized by subduction zone fluids. Combining with previous studies, we suggest volcanics from the southern Juoluotage area were formed in island arc setting which was related to southward subduction of Paleo-Asian Oceanic lithosphere. Early Carboniferous volcanics from Yamansu Formation represent juvenile intra-oceanic arc, while Late Carboniferous volcanics from Tugut Bulak formation indicate that the previous juvenile arc had evolved to a relatively mature stage. The composition and temporalspatial distribution of the volcanics in the study area reveals the southward thickening of lithosphere during Carboniferous, which provides strong evidence for the southward subduction of the southern margin of Tuha oceanic crust. Related Articles | Metrics

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Influential factors of pore structure and quantitative evaluation of reservoir parameters in carbonate reservoirs QIN Rui-Bao, LI Xiong-Yan, LIU Chun-Cheng, MAO Zhi-Qiang 2015, 22(1): 251-259.  DOI: 10.13745/j.esf.2015.01.021 Abstract ( 1926 )   PDF (1965KB) ( 854 )   In recent years, a large number of porous carbonate reservoirs have been explored and developed in overseas blocks. Due to the complex lithologies and pore types, the pore structure is very complicated. Therefore, it is difficult to accurately calculate the reservoir parameters and evaluate oil and gas reserves. In order to accurately evaluate carbonate reservoirs, firstly, the influential factors of pore structure are analyzed based on the deposition and the diagenesis. As a result, in different lithologies, the difference between pore types is the main reason for a large difference between pore structures. In the same lithology, the increase in clay content can reduce the quality of pore structure. In addition, the diagenesis has a large impact on the rock with the larger particle size. Secondly, the quantitative evaluation of reservoir parameters is discussed. Due to the coexistence of different types of pore, the reservoir parameters including the permeability and the saturation are quite different while the porosity is similar. In order to solve this problem, the NMR and imaging logging data can be applied to characterizing the numerical distribution of different pore types. Additionally, the three-dimensional imaging technique can be used to show the spatial distribution of different pore types. This study laid a foundation for the accurate calculation of reservoir parameters and objective evaluation of oil and gas reserves. Related Articles | Metrics

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A discussion on the tectonic inversion and its genetic mechanism in the East China Sea Shelf Basin ZHANG Guo-Hua, ZHANG Jian-Pei 2015, 22(1): 260-270.  DOI: 10.13745/j.esf.2015.01.022 Abstract ( 2742 )   PDF (1858KB) ( 2502 )   Through the analysis of the inversion structures in each secondary tectonic unit of the East China Sea Shelf Basin, we considered that the Cenozoic inversion structures were mainly as anticline，associated with thrust fault. There were four main tectonic inversions: Oujiang movement(T80)，Yuquan movement(T30)，Huagang movement(T20) and Longjing movement(T12); while such tectonic inversions had significant differences in time and space. In time evolution scale，the tectonic inversions were relatively weakened from Oujiang movement(T80) to Huagang movement(T20) in the West Depression Belt，and on the other hand they were relatively enhanced from Yuquan movement(T30)，Huagang movement(T20) to Longjing movement(T12) in the East Depression Belt. In space evolution scale，The Longjing movement(T12) in Xihu Sag and Diaobei Sag of the East Depression Belt had weakened trend significantly from north to south. The intensity distribution and migration evolution of Cenozoic tectonic inversions were the local response in the East China Sea Shelf Basin affected by the subduction rate and direction of plates interactions between Indian Plate with Eurasian Plate and Pacific Plate with Eurasian Plate. Related Articles | Metrics

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Research on hydrocarbon distribution regularity and main accumulation controlling factors of Tazhong northern slope hydrocarbonrich region ZHANG Bao-Tao, YU Bing-Song, ZHU Guang-You, WANG Yu, SU Jin, WANG Kai, LIU Xing-Wang 2015, 22(1): 271-280.  DOI: 10.13745/j.esf.2015.01.023 Abstract ( 1643 )   PDF (1680KB) ( 905 )   In the northern slope of Tazhong in Tarim Basin, Ordovician is the main hydrocarbon exploration target, and many hydrocarbon reservoirs have been discovered in this horizon. There are multiple reservoir types in this area, with complicated oil/gas/water distribution and various oil/gas characteristics. By analyzing mass wells production performances as well as testing data and discussing the distribution of fluids, faults, reservoir and high capacity or water wells, the oil/gas distribution regularity and its main controlling factors were revealed. The weathered crust unconformity developed in the top of O1y controlled the reservoir depth and reservoir thickness vertically; the horizontal inhomogeneity of the reservoir was the important reason for the oil/gas differential distribution. Height difference caused by fault had apparent impact on fluid accumulation, and structural high in the upside was more apt to oil/gas accumulation; the faults have seriously reformed the reservoirs, and the strikeslip faults as the migration pathway had obvious control action on oil/gas distribution especially, which decided the gas cutting intensity of different fossil reservoirs in the late Himalayan and the different phase reservoirs distribution. The tightlayer located in the upper part of O1y was significant for the fossil reservoirs preservation. This study will serve as an important reference to the hydrocarbon accumulation regularity research and exploratory development in the similar carbonate region. Related Articles | Metrics

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Composition and genesis implications of hydrocarbons in 49.6°E hydrothermal area, Southwest Indian Ocean Ridge LEI Ji-Jiang, CHU Feng-You, YU Xiao-Guao, LI Xiao-Hu, TAO Chun-Hui, GE Qian 2015, 22(1): 281-290.  DOI: 10.13745/j.esf.2015.01.024 Abstract ( 1616 )   PDF (1387KB) ( 855 )   Molecular composition of extractable and detectable organic matter in hypothermal product from 49.6°E hydrothermal vent field were analyzed by GC and GC-MS. Combined with the analysis of biomarkers and individual isotopic composition, we discussed the composition, origin and genetic implication of hydrocarbons. N-alkanes(3.4373.962 μg/g) are the main hydrocarbon of sulfide chimney, with low L/H ratio (<1) and slight odd carbon number predominance in >C22 alkanes (CPI=1.1401.209); NAR is close to 0. Sulfide chimney has a variety of biomarkers (Sq, IS40, cyclohexylalkanes) ; 22S/(R+S) of C31 hopanes achieved 0.77; 17β(H) and 21β(H)hopanes were absent. The fatty acid of sulfide chimney is comprised of short chain saturated fatty acid and iso/antiiso fatty acid, and lacks monounsaturated fatty acids. Isoalkanes(2.094 μg/g)are the main hydrocarbon of hydrothermal altered rock; n-alkanes are characterized by more low carbon (L/H=1.33) and even carbon number predominance (CPI=0.377); monounsaturated fatty acids are the most abundant fatty acid. These results suggested that the autochthonous organisms were the major source of hydrocarbons in 49.6°E hydrothermal area, and that the temperature and chemical condition of hydrothermal fluid constrained the distribution of hydrothermal community and the composition of hydrocarbon of hydrothermal product. The molecular evidence for the abiogenic synthesis of organic compounds was rare, however, the coexistence of methanogens and sulfate reducing bacteria indicated that H2 were rich in hydrothermal fluids of 49.6°E vent and the abiogenic synthesis approach could not be neglected. Related Articles | Metrics

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Oil and gas distribution features and mail controlling factors of the North Sakhalin basin, Russian Far East HE Zheng-Jun, ZHANG Guang-Ya, WANG Zhao-MIng, LIANG Ying-Bo, WANG Yong-Hua 2015, 22(1): 291-300.  DOI: 10.13745/j.esf.2015.01.025 Abstract ( 2126 )   PDF (1868KB) ( 1535 )   On the basis of the analysis of petroleum geological conditions and the known fields of the North Sakhalin basin in the Sea of Okhotsk, Russian Far East, the author summarized the oil and gas distribution features of the North Sakhalin basin, and then combining with the analysis of tectonic evolution, discussed the main controlling factors of hydrocarbon accumulation. The results show that the hydrocarbon distribution of this basin has the features that the scale of onshore reserves is much smaller than that of the sea shelf reserves, and it can be longitudinally divided into 2 large plays, however, the oil and gas are mainly enriched in the Dagi Formation and Nutovo Formation, which are obviously zonal in planar distribution, the Dagi Formation reservoirs are mainly distributed in the landward inner zone and the Notovo Formation reservoirs are mainly distributed in the outside zone far from land. The hydrocarbon accumulations are mainly controlled by multicycle tectonic evolutions, hydrocarbonrich depression and different intensity in tectonic activities. Low amplitude uplifted structure zones in the postrift depression of the sea shelf are the major favorable exploration targets for accumulation of high abundance mediumlarge oil-gas fields. Related Articles | Metrics

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The characteristics of the Upper Permian shale reservoir in the northwest of Guizhou Province, China. LI Juan, YU Bing-Song, XIA Xiang-Hua, TIAN Yu-Kun, LI Ying-Lie, ZHOU Hui, MA Yong-Sheng 2015, 22(1): 301-311.  DOI: 10.13745/j.esf.2015.01.026 Abstract ( 1750 )   PDF (2019KB) ( 1469 )   Although there are series of strata with gasbearing shale in Guizhou Province, the main work was focused on the black shale of Cambrian and Silurian systems instead of the Upper Permian Longtan Formation. In order to make up such shortage, the black shale of the Upper Permian Longtan Formation in the northwest of Guizhou Province was studied by the Xray diffraction mineral analysis of whole rock, by the tests of surface area, TOC and Ro, and especially by the field emission scanning electron microscopy. The average content of quartz is 47.8% with the highest content in the middle and south of Dafang County, and clay minerals is 41.4%, which decreases first then increases from north to south. The researched pores are mainly mesopores and have a periodic trend from north to south. A classification, consisting of three major pore types, i.e., interparticle pores, intraparticle pores and organicmatter pores, is presented. It is worth mentioning that organicmatter pores are abundant and of great importance. With increasing TOC, micropore volumes relatively increase. The volumes of mesopore increase with a greater sum of clay minerals. And quartz contributes to the sum of macropores. Thus qualitative observation by the field emission scanning electron microscopy verified the quantitative experimental analysis. Related Articles | Metrics

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The impact of salt layer thickness on the structural characteristics and evolution of detachment folds in the leading edge of Kuqa fold and thrust belt TANG Peng-Cheng, RAO Gang, LI Shi-Qin, WANG Ren-Fu 2015, 22(1): 312-327.  DOI: 10.13745/j.esf.2015.01.027 Abstract ( 1700 )   PDF (3007KB) ( 812 )   Detachment folds are widely distributed in the leading edge of Kuqa fold and thrust belt (KFTB). Although the Cenozoic sedimentary strata involved into the structural deformation and their underlying basal detachment (Paleogene salt layer) are the same, the structural characteristics and the evolution of detachment folds are quite different. In this paper, on the basis of the field observations and the interpretations of highquality seismic and well data, we demonstrate the initial salt layer thickness and discuss their relations to the deformation styles and the evolution of detachment folds, taking the examples from the Nanka and Misikantage anticlines. The results of our analysis indicate that the initial underlying salt layer of Nanka anticline is about 0.10.5 km in thickness, generally of 0.10.3 km, which is in contrast to the Misikantage anticline with thickness of as much as ~ 1.0 km. Meanwhile, the alongstrike variations in the structural styles have been observed both in the Nanka and Misikantage anticlines. The Nanka anticline is a lowamplitude detachment fold, whose eastern segment is buried under the ground surface and characterized by the folding deformation. However, in its western segment the fold with relative higher average upliftrate is consequently exposed on the surface associated with both folding and thrusting, as evidenced by thrust faults developed at the core of anticline. In contrast, the Misikantage anticline is a largescale detachment fold, which can be divided into three segments of different geometry. The northvergence of the anticline in the eastern segment are different from the southvergence of the anticline in the central and western segments. Meanwhile, thick salt is mainly accumulated underlying the north limb and at the core of anticline in the eastern segment, which is in contrast to the salt accumulated at the core of anticline, thinning towards both limbs and even forming the salt welds in the central segment, and also obviously different from the boxfold with underlying salt layer of at least 1 km in thickness in the western segment. In summary, seven distinct deformation styles of detachment folds in the leading edge of KFTB have been demonstrated, and, according to our analysis, the deformation style of detachment fold was strongly affected by the salt layer thickness, compressive shortening and salt flow. Among them, the salt layer thickness was dominative in controlling the deformation style of detachment fold. The results of this study concerning about the structural characteristics and evolution of detachment folds and their controlling factors might be helpful for the investigations of the detachment folds in other fold and thrust belts, especially within the regions without highquality seismic data or poor quality due to intense strutural deformation. Related Articles | Metrics

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An experimental study of Desulfovibrio sp. anaerobic degradation of >C12 organic compounds of Huainan coal GE Xiao-Guang, CHENG Jian-Ming, YANG Liu, YE Yong-Kang, CHEN Liu-Wang 2015, 22(1): 328-334.  DOI: 10.13745/j.esf.2015.01.028 Abstract ( 1594 )   PDF (1093KB) ( 545 )   An experiment was made to study the anaerobic metabolism of organic components in coal by the SRBs (sulfate-reducing bacteria) using the groundwater samples of the Carboniferous Taiyuan Formation limestone aquifer containing bacteria and the coal samples of Shanxi Formation from mine-pit of 530 m depth at Panbei coal-mine in Huainan coal-field. A SRB strain S890 was cultured and isolated from the groundwater samples and was identified as Desulfovibrio sp. by S16 rRNA gene sequencing. The methanol extracts of the coal samples were analyzed with GC-MS, and 21 kinds of chief organic compounds were identified known as senior chain, cyclic and aromatic hydrocarbons as well as hydrocarbon derivatives. Three >C12 compounds (2,6-Di-tert-butyl4-methylphenon, 2-hexyl1-Decanol and Naphthalene,2,6-dimethyl) selected from the 21 compounds were measured as carbon sources in a 27-day SRB anaerobic cultivating experiment and concentration variation of SO2-4, H2S and FeS during the cultivating procedure in the controlled experiment, and the results reflected that 2,6-Di-tert-butyl4-methylphenon and 2-hexyl1-Decanol were evidently anaerobically degraded by Desulfovibrio sp., but Naphthalene,2,6-dimethyl was not. It was concluded from the experiment that the SRBs in groundwater in coal seams utilized some macromolecular organic compounds in the coals as carbon sources for their anaerobic growth. Related Articles | Metrics

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The enhanced geothermal system(EGS): Huge capacity and difficult exploitation LIAO Zhi-Jie, WAN Tian-Feng, ZHANG Zhen-Guo 2015, 22(1): 335-344.  DOI: 10.13745/j.esf.2015.01.029 Abstract ( 2073 )   PDF (1511KB) ( 1104 )   This paper includes five parts: Why should exploit Hot Dry Rock (HDR) geothermal resources? What is Hot Dry Rock system and Enhanced Geothermal System (EGS)? How much is the potential of HDR system in China? How are we to develop EGS in China? and the last one is our recommendations. With the conventional energy sources continually consumed, the renewable energy sources is increasingly favored by people. In renewable energies, the geothermal energy is with huge capacity and the geothermal power generation can provide the basic load, but its development has lagged behind wind and solar energies due to many factors. In particular, the research and development of Enhanced Geothermal System with huge capacity and difficult of exploitaition are just beginning in China. If geothermal electric energy production must surpass wind and solar energy, the development and utilization of geothermal energy can not only rely on the hydrothermal systems, but must pay attention to the utilization of HDR and to the research and development of EGS. How much is the potential of HDR system in China? Based on 921 heat flow data,the heat flow map and deep temperature map (at 310 km) of Chinese Mainland has been prepared by the Institute of Geology and Geophysics of Chinese Academy of Sciences. They calculated subsurface temperature and HDR resources at different depth of about 2.09×107 EJ. Among them, the Qinghai-Tibet Plateau occupied one fifth of the total of resources. The authors argue that the exploitation of HDR and establishment of EGS is a systematic project. The geothermal development is a risk investment and the sub-economic EGS has a greater risk. The state should make unified arrangement and investment. The project must learn from foreign experience and lessons of exploitation. A key area has been selected for testing and research. The authors thought that the northern part of Yangbajain Geothermal Field in Tibet is a better choice to be a test area. Related Articles | Metrics

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Present tectonic stress adjustment process before and after Japan MW 9.0 earthquake in North and Northeast China and its research significance TAN Cheng-Xuan, HU Qiu-Yun, ZHANG Peng, FENG Cheng-Jun, QIN Xiang-Hui 2015, 22(1): 345-359.  DOI: 10.13745/j.esf.2015.01.030 Abstract ( 1648 )   PDF (2332KB) ( 876 )   In order to discuss present tectonic stress adjustment process before and after Japan MW 9.0 earthquake in North and Northeast China and its research significance, the measurement of present insitu absolute crustal stress state (including magnitude and orientation) and the realtime monitoring of crustal stress values and GPS measuring in North and Northeast China were carried out. The research results show that the adjusting periods of the tensile effect triggered by Japan earthquake coseismic displacement in Shandong peninsula, north region of North China and Northeast China are about 6 months (the adjustment ended about in September 2011), 15 months (the adjustment ended about in June 2012) and 26 months (the adjustment ended about in May 2013), respectively, and that the adjusting cycle of the tensile effect is proportional to the size of coseismic displacement. In this adjustment process, the conversion of the regional tectonic stress action way and tectonic stress field may have happened, which may cause the major geological events (such as earthquakes and so on). The earthquakes, such as MS 4.8 on May 28, 2012, MS 3.2 on May 29, 2012, MS 4.0 on June 18, 2012, MS 3.3 on August 26, 2012, and MS 3.0 on January 11, 2013, in Tangshan and its around region, may be triggered by the conversion in the northern part of North China, and the earthquake swarm in Songyuan city in Jilin Province since October 31, 2013 may be caused by the conversion in Northeast China, rather than small earthquakes before a strong earthquake. Related Articles | Metrics

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Water content and element geochemistry of peridotite xenoliths hosted by Cenozoic basalt in Longgang and Wangqing, Jilin Province ZHAO Qi-Chao, XIA Qun-Ke, LIU Shao-Chen, CHEN Huan, FENG Min 2015, 22(1): 360-373.  DOI: 10.13745/j.esf.2015.01.031 Abstract ( 1738 )   PDF (1620KB) ( 733 )   This paper presents major and trace element data of minerals (clinopyroxene (Cpx), orthopyroxene (Opx), olivine (Ol), and spinel (Spl)) from peridotite xenoliths hosted by Cenozoic basalts in Longgang and Wangqing, Jilin Province, which were obtained by EMP and LAICPMS respectively. Covariances in element contents of peridotite minerals suggest that the peridotite xenoliths are relicts of primary mantle after different degrees of partial melting. Elevated content of highly incompatible elements in some clinopyroxenes demonstrates that the Longgang and Wangqing lithospheric mantle has undergone subsequent mantle metasomatism; the major metasomatic agent was silicate melt and/or with minor carbonatite melt. Both clinopyroxene and orthopyroxene show prominent absorption bands in the range of 3 0003 700 cm-1, which are due to hydroxyl defect in their crystal structure; no discernable OH peaks can be found in olivine grains. The water content (H2O wt.) of clinopyroxene and orthopyroxene from Longgang are calculated to be ranging from 48×10-6 to 464×10-6 and 28×10-6 to 104×10-6 respectively; that of same minerals from Wangqing ranges from 34×10-6 to 403×10-6 and 13×10-6 to 89×10-6 respectively. Based on the water content and mineral model, it is estimated that the wholerock water contents of the Longgang and Wangqing peridotites vary in the range of (892)×10-6. The water contents of peridotites can reflect the information on lithospheric mantle in this region, and the large variations in the water content may be resulted from the heterogeneity of the primary water content in the mantle source and combined with the superimposition of partial melting and metasomatism events. Related Articles | Metrics

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Characteristics and controlling factors of the formation of pores of a shale gas reservoir: A case study from Longmaxi Formation of the Upper Yangtze region, China HUANG Lei, SHEN Wei 2015, 22(1): 374-385.  DOI: 10.13745/j.esf.2015.01.032 Abstract ( 1702 )   PDF (2176KB) ( 1123 )   Through the studies using SEM, Ar-ion mille FESEM and NMR technologies, the characteristics of the formation of micron-size pores, nanoscale pores and microfractures of the Longmaxi Formation shales were quantitatively characterized. Based on the test data of TOC, Ro, and X-ray diffraction analysis of mineral composition, the controlling factors of forming characteristics of the above three kinds of pores were analyzed. The positive factors for the development of micron-size pores are quartz content and illite content, and the negative factors are depth and carbonate content. The positive factors for the development of organic matter pores are Ro and illite, smectite content, and the negative factor is calcite content. The positive factors for the development of micro-fractures are quartz content, Ro and TOC, and the negative factor is calcite content. Related Articles | Metrics

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Using the stratal slice to study the depositional characteristics of deep-water slumped turbidite fans in continental lake basin DONG Yan-Lei, SHU Xiao-Min, GENG Xiao-Ji, WANG Hai, WANG Mao-Wen, Jiang-Qing-Mei, DU Yuan-Zong 2015, 22(1): 386-396.  DOI: 10.13745/j.esf.2015.01.033 Abstract ( 1652 )   PDF (2511KB) ( 890 )   The upper He-3 sequence of the Biyang Sag is used in this paper as an example to illustrate the workflow of Seismic Sedimentology. On the basis of subtle sequence framework, a stratal slice cube was made which displayed the distribution of sedimentary microfacies, and the analysis of the cube enabled the interpretation of the evolutionary history. Through the comprehensive analysis of core, lithology and well-logging, the sandbodies of the typical slices were interpreted elaborately, and some conclusions were drawn as follows. There exist three denuded areas in the north-east, south-east and south-west, respectively, which provided the terrigenous clasts to the deep depression of the Biyang Sag, and where developed correspondingly the three sedimentary formations, i.e., the Houzhuang braided delta in the north-east, the Lishuwa nearshore subaqueous fan in the south-east and the Yangqiao nearshore subaqueous fan in the south-west. In the deep depression, slump turbidite fans were developed. The progradational configuration of braided delta front always associated with the lenticular reflection in strike direction, which showed the process of the sand bodies sliding from delta front into semideep to deep lacus and being wrapped by mudstone. Finally, the paper predicts the distribution of sedimentary facies and provides the reliable evidence of exploration of subtle traps such as slump turbidite fans. The result was verified by Well Anshen 1. Related Articles | Metrics