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    2015, Volume 22 Issue 3
    15 May 2015
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    The classification of sedimentary basins and discussion on relevant issues.
    LIU Che-Xiang, WANG Jian-Jiang, DIAO Gong-Ge, ZHANG Dong-Dong, DENG Yu, DIAO Xiao-Chen
    2015, 22(3): 1-26. 
    DOI: 10.13745/j.esf.2015.03.001

    Abstract ( 2021 )   PDF (4147KB) ( 1947 )  

     The classification of sedimentary basins is fundamental for research on basins and related fields. Although there are a variety of basin classification schemes with different emphases and advantages, the study of the classification of intracontinental basins is still weak. A sedimentary basin represents a typical giant system and its classification is a complicated system engineering. The excellent classification for basins should reflect integrality, hierarchy, relevancy, typicality (representativeness) and comparability (predictability) of the basin system. The classification of basin types is mainly based on the factors, including tectonic position, lithospheric type, subsidence mechanism and dynamic environment, basinal texture and structure, basement property, sedimentary environment and filling feature, etc., during the formation and development of the basin. The forces which led to basin subsidence were mainly originated from the deep Earth and can be divided into four types: thermal, stress, gravity and combination of all the three. The basin formed by asteroid impact is a special case and could be classified into the gravityoriginated type. Another noteworthy basin type is the basin generated by landform genesis; the basin did not result from endogenic processes but caused by sediments and water body accumulating in lowland; this type of basin has been observed in different tectonic environments;their occurrence conditions of mineral deposits and geodynamic implications are quite different from those basins having endogenic genesis; therefore, the basin is separately treated as a basin type with distinctive origin. Based on previous classification schemes and studies of sedimentary basins and considering plate tectonics dynamic setting, independence and initiative of intracontinental internal dynamics, and main forces leading to basin subsidence, this paper divides the regional tectonic environment of basin development into 6 types: within oceanic plate, within continental plate, divergent, subduction, collision, and transform continental (plate) margin, plus newlyadded asteroidimpact and reformed composite types. Among the former 6 types, 44 subtypes of sedimentary basins are further classified according to their dynamic environments and major mechanical properties (stresses), respectively. We further discussed and explained about the newlyadded types and newlydefined types of basins and the terms which have been changed; these basins include backland basins, side continental basins, transformcompensation basins, pullrift basins, landform genesis basins, asteroidimpact basins, intermediate massif basins, intracontinental foreland basins, reformed basins and so on. This basin classification scheme is a rational and comprehensive induction based on the same or similar tectonic environment of the basins in various regions; it is relatively systematic and complete. In the geological history and today, a certain type of basin may have been absent or incompletely developed in somewhere having the same tectonic environment because of the differentiated geological conditions and changing of development processes. Every sedimentary basin classification scheme, from its birth, must be under test, controversy and construction. By doing this, it gradually becomes perfect.

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    Tectonic cycle of marginal oceanic basin: A new evolution model of the South China Sea.
    ZHANG Gong-Cheng, WANG Pu-Jun, TUN Jing-Fu, LIU Shi-Xiang, XIE Xiao-Jun
    2015, 22(3): 27-37. 
    DOI: 10.13745/j.esf.2015.03.002

    Abstract ( 1542 )   PDF (2162KB) ( 1076 )  

    The South China Sea is tectonogeographically composed of the central ocean crust, continental slopes, and continental shelves. The tectonic evolution of the marginal oceanic basin in the South China Sea includes two cycles: Paleo and New South China Sea tectonic periods, both of which had undergone formation and shrink stages. Prior to the PaleoSouth China Sea, there used to be a united basement in the present basin area before the Cenozoic. The PaleoSouth China Sea had undergone rifting, drifting and subduction stages. The two former stages are characterized by extension in the periods from the Late Cretaceous to the Eocene. The subsequent shrinking period was from the Oligocene to the Quaternary, and the related oceanic crust had been subducted and disappeared. The new South China Sea had undergone two construction stages including intracontinental rifting during the Paleocene to the Eocene and marginal continental drifting during the late Oligocene to the middle Miocene, which were followed by the shrinking episode since the middle Miocene. The shrinking stage was characterized by ceasing of the northsouth expansion in the area probably owing to the Philippine island arc westward obduction from the middle Miocene to the present. The two tectonic cycles of marginal oceanic basin controlled the regional tectonic patterns, natures of the component blocks, and attributes of the basin margins. As the results of the two tectonic cycles, the northern margin is a passive continental margin; its southern Nansha block is a drifted block from south; the southern edge is a kind of polyphase active continental margin; its western margin is bounded by strikeslip fault system; and the eastern part is enclosed by the Philippine Island Arc showing compressional features.

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    Tectonic dynamics of northern continental margin basins in South China Sea.
    CHEN Jian-Jun, MA Yan-Ping, CHEN Jian-Zhong, SUN Gui-Bin
    2015, 22(3): 38-47. 
    DOI: 10.13745/j.esf.2015.03.003

    Abstract ( 1600 )   PDF (1175KB) ( 921 )  

    Northern continental margin basins in South China Sea are located among Pacific Plate, Indian Plate and Philippine Sea Plate; these plates had different impacts on these basins. The study of the evolution of the three plates and paleoSouth China Sea showed that the stress environment had been changed in the late Cretaceous in northern continental margin area. The stress environment was compressional in the Lower Cretaceous and had been changed into extension in the Late Cretaceous. The cause of extensional environment was different since the Late Cretaceous. Extensional environment was caused by stress relaxation of eogenetic orogen in South China continental margin area, by southern subduction of paleoSouth China Sea and by rollback of the subducting Pacific slab from the late Cretaceous to the Paleocene, and the early rift basin began to form in continental margin in northern South China Sea. Continued reduction of western subduction rate of Pacific slab and southern subduction of PaleoSouth China Sea formed the same stress environment in the Eocene and rift basins formed continually. Southern movement of mantle materials and southern subduction of PaleoSouth China Sea formed the extensional environment from the Oligocene to the EarlyMiocene and seafloor spreading of South China Sea began in the Early Oligocene. The three plates affected these north continental margin basins in South China Sea together since the Middle Miocene.

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    Petroleum systems of the major sedimentary basins in Nansha sea waters (South China Sea).
    YANG Meng-Hui, ZHANG Hou-He, LIAO Zong-Bao, LUO Xiao-Hua, YANG Guang, GONG Ting
    2015, 22(3): 48-58. 
    DOI: 10.13745/j.esf.2015.03.004

    Abstract ( 1532 )   PDF (1677KB) ( 1564 )  

    The petroleum systems and their reservoirforming factors of the major sedimentary basins in the Nansha sea waters (South China Sea) were controlled by tectonic evolution and characterized by the basins of different types having similar basinfilling features, which means that the sedimentary features of contemporary strata are alike, and that the main unconformities formed almost at the same time. The major basins had undergone the synrift stage from the Paleogene to the Early Miocene and postrift stage since the Middle Miocene, so four various petroleum systems developed in the Nansha sea waters: (1) the lacustrine petroleum system of the earlyrift period has been developed in the western Nam Con Son Basin; (2) the transgressive delta petroleum systems of the laterift period have been developed in the eastern Nam Con Son Basin, the Balingian area in the Zengmu Basin, the Reed Bank Basin and the Northwest Palawan Basin; (3) the marine petroleum systems of the early postrift period have been developed in the Central, West Luconia and the East Natuna area of the Zengmu Basin; and (4) the regressive delta petroleum system of the late postrift period has been developed in the BruneiSabah Basin. The source rocks within these sedimentary basins are mainly the Miocene mudstone, and the coal strata only contribute to gasfield; the sedimentary facies of the source rock are dominated by the transitional facies, and nearly half of the oilgenerating are from the marine source rock, whereas the terrestrial source rock has little contribution to the hydrocarbon. The reservoir rocks are dominated by the Upper Miocene sandstone and the MiddleUpper Miocene limestone, and the former gathered oil, while the latter accumulated gas. The trap types of the oil reservoirs are dominated by the structural trap, and the stratigraphicstructural trap also has a considerable amount. The trap types of the gas reservoirs consist of the stratigraphic trap, stratigraphicstructural trap and the structural trap. The fractured igneous rock and/or metamorphic rock developed in the prerift period usually formed bedrock reservoirs.

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    Structural characteristics and main controlling factors of inversion structures in Xihu Depression in Donghai Basin.
    GUO Zhen, LIU Che-Xiang, TIAN Jian-Feng
    2015, 22(3): 59-67. 
    DOI: 10.13745/j.esf.2015.03.005

    Abstract ( 1769 )   PDF (1650KB) ( 776 )  

    Through seismic section study and sedimentarytectonic analyzing, based on the volume of uplift and associated fault, the inversion structures in the Xihu Depression of East China Sea shelf basin are divided into four types: wide fold, narrow fold, wide fold with reverse fault, and narrow fold with reverse fault. The inversion structures in the Xihu Depression are characterized by the zonation from east to west and the partition from south to north. The Central Uplift Belt has the strongest inversion structure, the East Marginal Belt is relatively gentle and the inversion in the West Marginal Belt is the weakest. The North Block comprises a lot narrow folds, while the Middle Block comprises strong inversion generally but weak in some places, The South Block have the opposite regulation to Middle Block. The inversion structures in the study area are mostly folds and supplemented with different degree of faults, so three parameters that are reverse displacement of inversion fault, amplitude of inversion fold and compression ratio in the Central Uplift Belt are chosen to quantitatively study the inversion characteristics in the Central Uplift Belt. The result shows that the inversion structure in the North Central Uplift Belt is strong, but limited; while the inversion structure in the Middle Central Uplift Belt is very strong or weak; the South Central Uplift Belt comprises strong inversion in some places, but weak mostly. The inversion structures in the Xihu Depression were caused by Longjing tectonic movement in the middlelate Miocene. The inversion faults were evolved by the reversal reactivation of preexisting normal fault; the reverse displacement generally reduced from bottom to the top. Inversion folds are more likely to develop on the top strata; it generally enhanced from bottom to the top. The subduction of Philippine Sea Plate to Asian Plate, caused Okinawa Trough to open, which caused the west boundary of Okinawa Trough to be pushed toward west. This push made the inversion structures in the Xihu Depression formed.

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    The control of hydrocarbon accumulation by strikeslip motion within the Bohai Sea Rise: A case study from Shaleitian Uplift.
    HUANG Lei
    2015, 22(3): 68-76. 
    DOI: 10.13745/j.esf.2015.03.006

    Abstract ( 1393 )   PDF (1690KB) ( 760 )  

    Although most oilfields discovered in the Bohai Sea were controlled by the NEtrending strikeslip fault, their controlling process was still poorly investigated. In this study, we choose the Shaleitian Uplift as one case to investigate the controlling process and mechanism of the NEtrending fault on the hydrocarbon accumulation. The result shows that the NEtrending fault had a longterm impact and cumulative effect on the hydrocarbon migration and accumulation. Two aspects about this impact are suggested: the Mesozoic sinistral motion of the NEtrending fault cut the basement, reworked the structural high of the basement, and consequently, controlled the migration pathways of hydrocarbon; whereas, the Cenozoic dextral motion of the NEtrending fault cut the draping structures and reworked the structural high of the Cenozoic strata, as a result, controlled the favorable site of hydrocarbon accumulation. Such understanding of the controlling process and mechanism of the NEtrending fault on the hydrocarbon accumulation can be widely referred in the hydrocarbon exploration of other areas offshore the Bohai Sea.

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    The Cenozoic distinct uplift events in the Liaodong Bay Depression and their geological significance.
    GU Nan, LIU Che-Xiang, ZHANG Gong-Cheng, HUANG Lei, DIAO Dun-Feng, LEI Shan
    2015, 22(3): 77-87. 
    DOI: 10.13745/j.esf.2015.03.007

    Abstract ( 1623 )   PDF (1740KB) ( 1034 )  

    On the basis of oil and gas exploration and geological data of the Bohai sea, we carried out the apatite fission track dating of the core, the interpretation of the seismic profiles, and the analysis of sedimentarytectonic characteristics and tectonic evolution of the Liaodong Bay Depression; the study suggested that there were three tectonic uplift and erosion events in the Liaodong Bay Depression in the Cenozoic, which occurred in the late Mioceneearly Pliocene (corresponding peak age of 57 Ma), in the end of Dongying period in the Oligoceneearly Miocene (corresponding peak age of 1822 Ma and 2426 Ma), and in the end of the third period of the Shahejie in the Eocene (corresponding peak age of 3640 Ma), respectively. These tectonic uplift events were different in different places: the events that happened in the southern part are earlier and stronger than in the northern part. In the Eocene, there was a big depression containing very thick sediment in the east of the study area. But after depositing, the third section of the Shahejie was reformed by faultcutting, and the Liaodong Uplift was formed and eroded strongly, so that the structure of “a rise in between two sags” was formed in the larger depression. The transformation process is relevant to the changes in activity feature and intensity of TanLu Fault; it may cause the difference in uplift characteristics and in the strength of later transformation between east and west in the Liaodong Bay Depression. The change in tectonic pattern of the Liaodong Bay Depression was related to regional dynamic environment and background closely. These three tectonic uplift events have profound impacts on East China. So our study is helpful in further improving and enhancing the entire understanding of Cenozoic basins in eastern China and offshore, and provides basic data and scientific basis for the study of regional dynamic environment and background, petroleum exploration and resource evaluation in East China.

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    Dynamic evolution of the MesozoicCenozoic basins in the northeastern China.
    ZHANG Xin-Zhou, GUO Ye, CENG Zhen, FU Qiu-Lin, BO Jian-Ban
    2015, 22(3): 88-98. 
    DOI: 10.13745/j.esf.2015.03.008

    Abstract ( 1506 )   PDF (1880KB) ( 1125 )  

    All MesozoicCenozoic basins in the northeastern China were not formed on the crystalline basement, and for the most part were superimposed on the unmetamorphosed Late Paleozoic sedimentary strata. The NenjiangKailu fault in the west and the JiayinMudanjiang fault in the east are the most important deep faults, which separate the northeastern China into three basement units, i.e., the ErgunHiggan, Songnen and Jiamusi massifs, and three corresponding MesozoicCenozoic basin groups from west to east. The west basin group is situated to the west of the NenjiangKailu fault and represented by the Mohe and Hailaer basins; the central one distributed between the NenjiangKailu and JiayinMudanjiang faults and represented by the Songliao Basin. The east basin group located to the east of the JiayinMudanjiang fault comprises many smallsized basins represented by the Sanjiang, Boli, Jixi and Hulin basins and so on. The three basin groups are distinct not only in the basement and lithosphere structures, but also in basin structures and fillings. The Mesozoic basinrelated volcanism is divided into three stages, i.e., the MiddleLate Jurassic (167147 Ma), the early Early Cretaceous(136126 Ma) and the late Early Cretaceous(122109 Ma). The MiddleLate Jurassic volcanic rocks were mainly developed in the Dahinggan Mountains to the west of the NenjiangKailu fault. The Early Cretaceous volcanic rocks are distributed in the whole northeastern China, and show an evolutional trend from west to east becoming younger and younger. The Jurassic and Cretaceous volcanism can be classified into two systems of geodynamic settings. The former is related to the extension after the compressional process of the North China Plate and Siberia Plate to the area. The MiddleLate Jurassic volcanic rocks in a NNW trending were superimposed on the EarlyMiddle Jurassic Mohe foreland basin and simultaneous coalbearing basins trending in an EW direction. The latter was related to the actions of the oceanic plates in the northwest Pacific to the area, including the basins formed since the Cretaceous. The revised chronostratigraphic chart of the MesozoicCenozoic basins in Northeast China indicates that the structures and fillings of the Early Cretaceous basins are different depending on their tectonic places how far from the continental margin, even if they formed nearly simultaneously. The Early Cretaceous basins in the west mainly developed the early Early Cretaceous fault basins filled by predominant volcanic rocks. The Songliao Basin in the central is characterized by late Early CretaceousLate Cretaceous successive depression sediments on the basis of the early fault basins. The many smallsized basins in the east part once were a unified Early Cretaceous continental marginal basin (PanSanjiang Basin) and marked by marineland transitional facies sedimentation. The unified basin was transformed and destroyed by thrust and sinistral slip faults in the last Early Cretaceous as the region close to the continental margin. Therefore, the present separate Early Cretaceous basins in the east part are relict basins.

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    The Cretaceous Songliao Basin: Dynamic background from volcanic rift to interior sag basin.
    WANG Pu-Jun, DIAO Ran-Lei, MENG Qi-An, JI Xue-Jiao, SHU De-Feng, GAO Wei-Feng
    2015, 22(3): 99-117. 
    DOI: 10.13745/j.esf.2015.03.009

    Abstract ( 1877 )   PDF (3359KB) ( 1019 )  

    On the basis of the new results of the CCSD (China Cretaceous Continental Scientific Drilling) and the integrated information concerning tectonic basin classification and 3D description of the Songliao Basin (SB), we reevaluate the type, tectonic evolution, and geodynamics of the SB according to systematical analysis of tectonic setting and basin fillings. The SB is on the northeast marginal zone of MongoliaNorth China Plate. It is united with the Siberian Plate by the MongoliaOkhotsk suture belt to the north, and connected with the Pacific Plate by SikhoteAlin accretionary belt to the east. The vertical filling successions of the SB can be subdivided into three tectonostratigraphic units by two regional unconformities which are on the top boundaries of the Yingcheng (K1y) (ca. 110 Ma) and Nenjiang (K2n) (ca. 79.1 Ma) Formations, respectively. The three tectonostratigraphic units are block faulting (Huoshiling to Yingcheng Formations), interior sag (Denglouku to Nenjiang Formations), and structural inversion (Sifangtai to Yian Formations) sequences. The block faulting sequence is a kind of volcanic rift basin, and the latter two all belong to the type of interior sag basin. In the block faulting period (150110 Ma), synrift volcanogenic successions were formed under the impact of regional extension that may be caused by the Plate reorganization from two sides, the northern and eastern active continental margins. The postrift basin fills (11079.1 Ma) may result from the superimposed subsidence of both post volcanic thermal declining and regional strikeslip pullapart effect. Widespread and thick source rocks deposited because of the high rate and undercompensation of sedimentation in this period. In the structural inversion period (79.140 Ma), depocenter of the SB migrated northwestward, and the basin was shrinking to demise. This was a result of the regional compression that should be caused by the Pacific Plate subduction under the eastern margin of the Eurasian Plate in the MidCretaceous to the Middle Eocene.

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    The distribution of Early Cretaceous faultedsags and their relationship with basement structure within Erlian Basin.
    QI Jia-Fu, DIAO Xian-Zheng, LI Xian-Beng, YANG Meng-Hui, XIAO Yang, XU Fu-Sheng, DONG Huo-Qi
    2015, 22(3): 118-128. 
    DOI: 10.13745/j.esf.2015.03.010

    Abstract ( 1566 )   PDF (1939KB) ( 764 )  

    The Erlian Basin is a continental rifting basin which is constituted by faulted sags in the styles of graben and/or halfgraben controlled by NENNE striking normal faults and was filled by the Lower Cretaceous. A lot of faultedsags concentratedly distributed in three rifting zones extending in different directions (ManiteWulanchabu rift zone, Wunite rift zone, and ChuanjingTenggar rift zone), and a few faultedsags were scattered over the uplift around the rift zone in the Erlian Basin. The basement of basin was constructed by multicycle tectonism and geological process before the Cretaceous, which was of heterogeneity in crustal nature and had a variety of structure lines. The strong deformation zones were mounted with weak deformation blocks; the former included foldthrust zone, suture zone and accretionary wedge; the latter included magmatic rock bodies, magmatic arcs or micro continental blocks, etc. The distribution and structural style of faultedsags were closely related to basement structure. The rift zone is also the strong deformation zone of basement. The various directions in basement strong deformation zone have caused the difference of rift zone in structural style and their arrangement of faultedsags. ManiteWulanchabu rift zone which superimposed on the WuzhumoqinErlian curve foldthrust zone that projected to southeast direction is the orthogonal rifting structure chaining graben and/or halfgraben in NNENE striking in series. Wunite rift zone which superimposed on the ErlianHegenshan suture zone (mélange zone) in NEEstriking is of oblique rifting structural feature combining graben and/or halfgraben together in rightstep echelons. ChuanjingTenggar rift zone which superimposed on the WenduermiaoXinamulun suture zone and accretionary wedge of north boundary of North China Craton in EW striking has also the typical oblique rifting structural feature combining graben and/or halfgraben together in highangle echelons or parallel connection. The Early Cretaceous faulted sags within orthogonal rift zone included long narrow but deep graben and/or halfgraben. The Early Cretaceous faulted sags within oblique rift zone included short wide but shallow graben and/or halfgraben. Abovementioned geological features demonstrate that the distribution and structural style of faultedsags in Erlian Early Cretaceous basin was controlled by basement structure.

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    Uplifting characteristics and its petroleum significance of Beidagang salient tectonic belt in Qikou Sag.
    ZHANG Dong-Dong, LIU Che-Xiang, HUANG Yi-Jian, DENG Yu, ZHANG Xiao-Long
    2015, 22(3): 129-136. 
    DOI: 10.13745/j.esf.2015.03.011

    Abstract ( 1414 )   PDF (1522KB) ( 653 )  

    Beidagang salient tectonic belt is the important part of central uplift belt of Qikou Sag, which is also one of the key areas to the research of the Cenozoic structure evolution of Qikou Sag. Research on the formation and evolution of the salient are particularly important for both basin structure evolution research and petroleum exploration. The paper subtly descripts the structure characteristics of different segments in Beidagang salient tectonic belt with the latest threedimensional seismic data, statistically compares the fault activity of the tectonic belts main faults in each period of the Cenozoic and restores the Cenozoic structure evolution of Beidagang salient tectonic belt by using balanced section technology. It is considered that Beidagang salient tectonic belt shows different structure characteristics in different segments and shows the characteristic of “one culmination and one steep slope” in NE direction; fault activities mainly occurred in Sha3 period, Sha1 period, Dongying period and Neogene; the Liugangzhuang fault and Dazhangtuo fault are lateral connected, so do the Binhai fault and Gangdong fault; the strength of fault activity shows the migration from SW to NE. In the Paleogene the salient underwent three major tectonic uplift events: SW segment partial uplift activity in late Sha3 period, slowly uplifting in Sha1 period and intensive uplifting in late Dongying period; and the structure activity strength migrated from SW to NE with time. The evolution of Beidagang salient tectonic belt provides favorable conditions for hydrocarbon accumulation in Qikou Sag.

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    Research ideas and methods for basin prototype sequence: A case study on basins of both sides of the East QinlingDabie orogenic belt.
    FANG Cheng-Ming, HUANG Ze-Guang, XU Xu-Hui, GAO Chang-Lin, LIU Yong-De
    2015, 22(3): 137-145. 
    DOI: 10.13745/j.esf.2015.03.012

    Abstract ( 1525 )   PDF (1468KB) ( 910 )  

    The present complex texture of petroliferous basin is the results of superimposition and juxtaposition of basin prototype at the different geohistory stage. It is an effective way to speculate the distribution of the ancient sedimentary depression, the process of hydrocarbon generation and accumulation, the distribution of oil and gas pools, that reverting and reconstructing the basin prototype evolution sequence of reformed basin. It is proposed that the research ideas and methods for basin prototype sequence and 4 supporting key technology, based on analyzing the ideas and methods of prototype analysis. The key supporting techniques including orogenic ancient ocean recovery, intercontinental deformation analysis, prototype basin sequence mapping and dynamic simulation of basin. Taking the NeoproterozoicEarly Paleozoic basin of the East QinlingDabie orogenic belt and adjacent areas as an example, reconstructed the evolution process of the ancient China ocean and its corresponding basin prototype sequence. The expansion of ancient China ocean and the northward subduction event determined the different basin evolution process of its both sides of the Early Paleozoic basin. The basin evolution since the Mesozoic and Cenozoic, represents multi period tectonic transformation and basin superposition resulting the large difference of hydrocarbon source thermal evolution and multiple oil and gas accumulation types. The results shows that the application of prototype basin sequence analysis method is feasible and necessary for assessment of geological in reformed petroliferous basin, and which can make a whole knowledge of the hydrocarbon source rock distribution under the control of basin prototype and the petroleum response under the superposition of basin prototype.

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    Tectonicscontrolled distribution of marine petroleum accumulations in the Sichuan Basin, China.
    LIU Shu-Gen, SUN Wei, SONG Jin-Min, DENG Bin, ZHONG Yong, LUO Chao, DAN Bei, TIAN Yan-Gong, LI Zhi-Wu, BANG Han-Lin, YIN Ke-Wei
    2015, 22(3): 146-160. 
    DOI: 10.13745/j.esf.2015.03.013

    Abstract ( 2028 )   PDF (2427KB) ( 1026 )  

    Based on geophysics, geochemistry, logging and well data, the present paper has unraveled the tectonicscontrolled distribution of the marine petroleum accumulations across the Sichuan Basin. Sichuan Basin is a superimposed basin in western China, of which the marine petroleum accumulations are chiefly under control of composite factors including the intracratonic sags, paleouplifts and basinmountain systems. Both the MianyangChangning and KaijiangLiangping intracratonic sags which were formed during the Xinkai and Emeishan taphrogenesis respectively have a firstclass control on the petroleum geological conditions, in particular the source rock quality and reservoir properties, which made the marine petroleum accumulate preferably in the periphery of the intracratonic sags. The paleouplifts formed during the Caledonian and Indosinian movements are favorable areas of petroleum migration and accumulation. Furthermore, the basinmountain systems have a significant effect on petroleum preserving conditions that controlled the final distribution of the marine petroleum, in particular during the LateMesozoic and Cenozoic times. Therefore, the favorable areas for marine petroleum exploration are those areas where the intracratonic sags, the paleouplifts and the basementcontrolled upliftbasin area or marginplate basinmountain systems superimposed across the Sichuan Basin.

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    Superposed evolution of Sichuan Basin and its petroleum accumulation.
    WANG Hua-Jun, YANG Zhi-Ru, HAN Bing
    2015, 22(3): 161-173. 
    DOI: 10.13745/j.esf.2015.03.014

    Abstract ( 2014 )   PDF (2364KB) ( 3157 )  

    According to previous research and petroleum exploration data, the Sichuan Basin existing in the Yangtze Plate has been researched. The basin has undergone five evolution stages: Sinian faulted basin evolution, CambrianSilurian faulted basin evolution and inversion, CarboniferousPermianMiddle Triassic basin evolution, Late Triassic foreland basin and JurassicEarly Cretaceous large intracontinental basin evolution and the Late CretaceousCenozoic uplift evolution. Sinian, CambrianSilurian basin evolution was controlled by the peripheral NEtrending faults; basin strata are clastic, evaporite and carbonate rocks; the basement has a structural pattern of west uplifting and east depressing. The late Middle Ordovician tectonic events formed the Chuanzhong Uplift, and the late Silurian tectonic events led to the uplift and erosion of the basin as a whole. After a late Silurian tectonic deformation and uplift, the CarboniferousMiddle Triassic basin was characterized by epicontinental sedimentary evolution of carbonates and gypsumsalt rock; the basement has a structural pattern of southwest uplifting and northeast depressing in this stage. In the end of Maokou sedimentary stage, tectonic events led to the uplift and erosion of the basin; in the end of Middle Triassic, tectonic events formed the LuzhouKaijiang palaeohigh. The Late Triassic foreland basin was superimposed on the early marine basins; the basement has a structural pattern of east uplifting and west depressing in this stage. The JurassicEarly Cretaceous basin is a large intracontinental faulted basin; in the end of the Jurassic, tectonic events formed eastern Sichuan structural zone; in the end of early Cretaceous, tectonic events led to the demise of the basin and the overall uplift. The Late CretaceousCenozoic sediment was confined in the southwest of the Sichuan Basin. The evolution of superposed basins formed several sets of organicrich source rocks, such as Sinian, Lower Cambrian, Wufeng Formation of Upper Ordovician, Longmaxi Formation of Lower Silurian, Liangshan Formation and Longtan Formation of Permian, coalbearing formation of upper Triassic and lower Jurassic. The gypsum, salt, mud and coalbearing rocks developed in the Cambrian, Silurian, Permian, LowerMiddle Triassic, Upper Triassic and Jurassic were distributed with vertical superimposition and horizontal composite joint. These seal and source rocks formed highquality combinations within the basin, which is the basis of hydrocarbon enrichment. A highquality reservoir was developed under each set of highquality cap.The good reservoirtraps combination has become a necessary condition of oil and gas accumulation. There formed lower, middle and upper assemblages of exploration formations in the basin. Exploration results show that the palaeohigh, paleoslopes and ancient source rocks controlled the oil and gas distribution of the basin

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    The relationship between tectonicsedimentary evolution and tight sandstone gas reservoir since the late Paleozoic in Ordos Basin.
    YANG Hua, LIU Xin-She, YAN Xiao-Xiong
    2015, 22(3): 174-183. 
    DOI: 10.13745/j.esf.2015.03.015

    Abstract ( 1574 )   PDF (2162KB) ( 905 )  

    Ordos Basin dominantly developed tight sandstone gas reservoirs in the Upper Paleozoic, with great exploration potential as large geological reserve, more than 5 trillion m3. By analyzing the tectonic evolution history of the basin, combined with inclusion thermometry, zircon UPb dating and authigenic illite KAr dating etc., it is defined that the controlling role on Upper Paleozoic tight sandstone gas reservoir is the tectonic evolution since the Late Paleozoic. Studies have shown that sedimentary palaeotopography was gentle and tectonic subsidence was slow during the CarboniferousPermian, which formed source rocks and sandstone reservoir with great extent. During the TriassicMiddle Jurassic, sedimentation became rapid with significant compaction and siliceous cementation. Along with strong waterrock interaction, tight sandstone reservoir began to occur. Intensive tectonic activities with the occurrence of thermal tectonic events made a large number of natural gas generated and migrated to accumulate during the Late JurassicEarly Cretaceous, which resulted in forming tight gas reservoir. From the Early Cretaceous to present, some natural gas was lost, and lots of lowpressure gas reservoirs have formed due to stratum uplift and denudation.

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    LAICPMS detrital zircon dating and its provenance significance in Yanan Formation of the EarlyMiddle Jurassic in the northwestern margin of Ordos Basin.
    DIAO Gong-Ge, LIU Che-Xiang, WANG Hai-Ran, GAO Shao-Hua, LI Meng, ZHUO Yu-Zhou, JIAO Jian-Xin, ZHANG Sun-Xuan-Qi, JIANG Cheng
    2015, 22(3): 184-193. 
    DOI: 10.13745/j.esf.2015.03.016

    Abstract ( 1787 )   PDF (1393KB) ( 805 )  

    The EarlyMiddle Jurassic Yanan Formation widely distributed in the northwestern margin of Ordos Basin, and the outcrops scattered limitedly with similar lithological features. Many disputes still exist about the source areas of Yanan Formation due to the tremendous geological reformation since the Late Cretaceous. The zircon LaserAblation Inductively Coupled PlasmaMass Spectrometry (LAICPMS) UPb dating was used to determine the ages of the source areas of the Yanan Formation in the region. There are three samples selected from the sandstone of Yanan Formation in two areas, altogether 210 grains were dated, and 193 valid zircon ages were obtained. Most zircons from the samples of Helan Mountain showed circular belt images under the cathodoluminescence microscope and displayed the leftoblique distribution pattern of rare earth elements. Most of those zircons have the Th/U larger than 0.4 indicating the magmatic origin, and a few zircons were from the metamorphic rock in the area. Most zircon UPb dating ages are mainly of the Paleozoic with the major peak in the Permian. The secondary ages are of the Proterozoic. The zircons from Zhuozi Mountain area are with the similar characteristics both in the images under the cathodoluminescence microscope and in the rare earth element distribution pattern. There exists much difference in the zircon ages between the two areas. The old ages in Zhuozi Mountain possess great proportions; 66.7% are of the Late ArcheanProterozoic (mainly the Proterozoic); only 22.7% of the total ages belong to the Permian, and 10.6% are of the EarlyMiddle Triassic. Compared with the ages of surrounding ancient rocks, it is concluded that the main sources of the EarlyMiddle Jurassic in the northwest margin of Ordos Basin were the Proterozoic magmatic and metamorphic rocks in the Alashan PaleoBlock; for the north of Ordos Basin, the main source was the Hercynian granite in the Alashan PaleoBlock. The main provenance in Helan Mountain was the Hercynian magmatic rocks in the Alashan PaleoBlock, and the secondary source was the Proterozoic magmatic and metamorphic rocks(Helan Mountain complex)for its northwest. While the principal source area in the Zhuozi Mountain was Proterozoic magmatic and metamorphic rocks for the northwest and the Hercynian magmatic rocks and EarlyMiddle Triassic magmatic rocks acted as the minor source. There is difference in provenance ages among the two studied areas and the Ciyaobao area. More researches from the sedimentary and petrology need to be done to further describe the provenance attribute.

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    Sedimentary response of regional tectonic transformation in Late Triassic Yanchang period at the central and southern Ordos Basin.
    WANG Jian-Jiang, LIU Che-Xiang, GUO Zhen, ZHANG Dong-Dong
    2015, 22(3): 194-204. 
    DOI: 10.13745/j.esf.2015.03.017

    Abstract ( 1868 )   PDF (2292KB) ( 5459 )  

    Based on a large number of mineral quantitative identification data, the plane and vertical distribution and changing characteristics of the sandstone types, light minerals, lithic components, etc. have been systematically analyzed in the Group Chang 10Chang 1 Yanchang Formation at the central and southern Ordos Basin. The study revealed that during the deposition of Group Chang 8 and Group Chang 7, the Ordos Basin had undergone an obvious sedimentary changing event. Since the Period Chang 7, the deposition zones of southwest and northeast in the basin had became very different in the types of sandstone, the components of minerals and tectonic background of source region, but there was no such difference before Period Chang 7. The boundary of the two regions has been confirmed to be along the Huachi and Huangling line. Considering the tectonic setting of the development and other sedimentary and tectonic events in Ordos Basin, we proposed that the sedimentary changing event in Yanchang Period was closely related to the splicing and collision of North China and Yangtze Craton in the MidLate Triassic, causing the closure of Qinling Ocean. In other words, this event is the sedimentary response to the fully collision, strong uplift and denudation of Qingling Orogenic Belt. The study can provide scientific basis for further analyzing the tectonic property of source region, the sedimentary system division in basin, the distribution of sand bodies as well as the prediction of favorable reservoirs in Yanchang Formation. Meanwhile, new evidences and important clues for the construction and reformation of basin evolution and basinrange coupling in the Mesozoic are provided.

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    Stable isotope tracing on the formation of white sandstone in Yanan Group, northern Ordos Basin, and its geological significance.
    TUN Bai-Lin, WEI An-Jun, LIU Che-Xiang, SONG Zi-Sheng, HU Liang, WANG Dan, CUN Xiao-Ni, SUN Chi, LUO Jing-Jing
    2015, 22(3): 205-214. 
    DOI: 10.13745/j.esf.2015.03.018

    Abstract ( 1599 )   PDF (1427KB) ( 850 )  

    There are a mass of white sandstone in the top of Yanan Formation in northeastern Ordos Basin which formed the local large kaolin deposit, and its bearing horizons were similar and adjacent to Zhiluo Formation in DongshengHangjinqi Area. Studies have shown that the whitening was closely related to uranium enrichment and reservation, green alteration of the orecontrolling sandstone, carbonation and so forth. These phenomena were related to the flowrock effect which was caused by the upper Paleozoic natural gas migrating northward. This paper mainly talks about the formation process and geochemical genesis mechanism of the white sandstone through the stable isotope tracing. The paper also indicates that there existed a natural gas dissipation dynamics background in this area, and that the hydrogen and oxygen isotopes of the kaolinite revealed that the formation of kaolin deposit was based on low temperature hydrothermal event, with the same properties and events as Dongsheng uranium deposit. The silicon isotopes of the kaolinite were similar to the uranium silicon isotope data, but far different from the clay silicon isotope data, which further evidenced that the white sandstone and uranium mineralization were the products of the same low temperature hydrothermal events. Carbon and oxygen isotopes showed that the white sandstone formation fluid was associated with organic matter source. Combined with organic geochemistry of Dongsheng sandstone type of uranium deposits and local geological background events of natural gas dissipation, it is suggested that the organic matters came from the natural gas dissipation northward in the Upper Palaeozoic. The characteristics of hydrogen and oxygen isotope of calcite inclusion indicated that the water of the fluid was atmospheric precipitation. In summary, the forming processes of white sandstone in the study area were as follows: the microthermal natural gas in the Upper Palaeozoic migrated from the central part northward to the shallow YananZhiluo Formations; this microthermal natural gas along with the underground water made up the microthermal mixed hydrothermal “natural gaswater”; the reduction effect of hydrocarbons in the microthermal liquid also led to the alterations, causing the formation of white sandstone in the top of Yanan Group and the Dongsheng uranium deposit in Zhiluo Formation, causing the greenization of the sandstone, the carbonatization and so on. These alterations formed the Dongsheng super large uranium deposit, super large kaolin deposit and hydrocarbon alteration. These all brought about the situation that multienergy sources and ores coexisted in the same basin with common prosperity.

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    Sedimentary boundary evolution of the Carboniferous in Northern NorthSouth Tectonic Belt, China and its geological significance.
    GUO Pei, LIU Che-Xiang, WANG Jian-Jiang, DENG Yu, DIAO Xiao-Chen, WANG Lei, ZHANG Xiao-Long, WANG Wen-Jing
    2015, 22(3): 215-226. 
    DOI: 10.13745/j.esf.2015.03.019

    Abstract ( 1470 )   PDF (2197KB) ( 818 )  

    NorthSouth Tectonic Belt is an important boundary of Chinese Mainland geological structure, of deep geologic processes and of surface system, which is also an earthquakeprone zone. Yet there is little or even less research about its existence before the Mesozoic and about its tectonic feature and connection between different regions in different period. By studying the Northern NorthSouth Tectonic Belt and focusing on its central and south part, this article discusses the Carboniferous geological structure and its connection to the formation and evolution of NorthSouth Tectonic Belt which has regionalization effect. During the Carboniferous, the Northern NorthSouth Tectonic Belt was in an extensional rifting environment with intense fault activities, and it controlled the east boundary, structural pattern and thickness of Hexi CorridorNorth Qilian sedimentary domain. Its fault activities and sedimentary evolution underwent four stages: Qianheishan initial rifting period, Chouniugou further expanding period (northward), Tupo flourishing period and Taiyuan attenuating period. In the late Tupo period (Benxi) and Taiyuan period, the east (North China) and west sedimentary domain both expanded to the north part of the NorthSouth Tectonic Belt where the boundary was partly connected in its north part and later totally connected. The faults in the Carboniferous have obvious relevance to the MesoCenozoic ones in location and direction, which means that their formation and evolution was related closely. In the Carboniferous, the Northern NorthSouth Tectonic Belt and its neighborhood divided the sedimentary ranges of North China and Hexi CorridorNorth Qilian. The separationtounion evolution of sedimentary boundary, structural feature and main controlling factors showed that this zone was an important geological tectonic unit with obvious partition function in the Carboniferous, and it would have laid the foundation of further evolution of NorthSouth Tectonic Belt and of its important tectonic status.

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    Regional tectonic framework and evolution of superimposed basins in northwestern China.
    HE Chi-Liang, GAO Shan-Lin, ZHENG Meng-Lin
    2015, 22(3): 227-240. 
    DOI: 10.13745/j.esf.2015.03.020

    Abstract ( 2689 )   PDF (2505KB) ( 1149 )  

    The northwestern China is a component of several global tectonic units in different geological periods, with the structural characteristics of NS zoning and EW districting. This area underwent crustal growth, oceancontinent transition, and oceanic basin open and close cycles in the Middle Neoproterozoic to the Paleozoic. The evolution process has obvious periodic characteristics, with superimposing and rebuilding since the Late Permian and with the far source effect of India and Eurasia plate collision in the Cenozoic. Most basins are based on the variable sized PreSinian crystalline basements; the basements of Tazhong, Tabei, and Tadong areas may be of the Proterozoic, whereas basement of Bachu region was Jinning period metamorphic rocks; The Junggar Basin based upon different sized independently developed preSinian basements displayed the tectonic pattern of archipelagic ocean during the Paleozoic. Many smallmedium size basins in the Hexi Corridor, the Qaidam Basin and adjacent areas were developed on small blocks or Paleozoic active continental margin arcs with crystallized Proterozoic basements, and different metamorphic events took place and formed bolded basement under the Dunhuang Basin. The northwestern China underwent a full plate open close cycle in the early Paleozoic, accompanied with diversified presentation in different regions. The ophiolites occurred more than three times in the northern Xinjiang region in the CambrianEarly Ordovician, the Silurian and the Devonian, respectively, which were identified as certain scale oceanic basins in the Paleozoic with different closing periods in disparate area. The South Tianshan ocean around Tarim Basin and oceanic basins developed around West Kunlun, Arkin, Qilian, East Kunlun, and Beishan underwent oceanic basin expansion from the Middle and Late Cambrian to the Early Ordovician, with the tectonic setting transition from the compressional system to the tensional system in the late period of the Early Ordovician. In the Late Silurian to the Early Devonian, the convergence and collision of plate and varying degrees of deformation and metamorphism occurred in northwestern China. Also, a complete plate breakup and close cycle was developed in the Late Paleozoic. The east and west sides of the Tianshan region and south Junggar underwent large scale postcollison extensional tectonic setting and formed the limited ocean basins at different periods with structural transformation between the early and the Late Carboniferous. The Early Carboniferous extension of southwest Tarim initiated the Late Paleozoic west Kunlun ocean and continental margin rift basin. The late Hercynian movement in the middle and Late Permian was a significant transformative movement in northwestern China. From the Late Permian to the Cenozoic, the multistage tectonic adjustment was developed and the tectonic framework was finalized in the northwestern China. On the background of intracontinental multiplate convergence, the western basins have undergone tectonic evolution of episodic multistage compression and extension; they are not simply the combination of the foreland basins as given by early researches. Compressional stress initiated by the remote effects of the rapid uplift of Qinghai Tibet Plateau made profound reform in the northwestern region. In the northwestern basins, the different development and combination models resulted from the different evolution phases and tectonic patterns. The petroleum geological conditions and the abundance of oil and gas are significantly different.

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    Carboniferous basin evolution and its hydrocarbon accumulation in the north of Xinjiang.
    TANG Yong, WANG Gang, ZHENG Meng-Lin, CHEN Lei, FENG Chi, KONG Yu-Hua, WEI Yan-Shao, LAI Shi-Xin
    2015, 22(3): 241-253. 
    DOI: 10.13745/j.esf.2015.03.021

    Abstract ( 1569 )   PDF (2405KB) ( 1166 )  

    The tectonic evolution of the Carboniferous sedimentary basins was researched based on recent exploration data and previous research results in the north of Xinjiang. The basins were developed with the geological setting of microblock, multicollision, weak consolidation and tectonic activation. During the Carboniferous, the region had undergone two stages of superposed basin evolution. The Carboniferous basins were strongly transformed from the Permian to the Cenozoic. The Carboniferous volcanic rocks were widely developed; they were formed in the Carboniferous extensional tectonic setting according to comprehensive analysis of drilling geochemical samples. Based on the deposition and distribution of the Carboniferous, the Early and Late Carboniferous basin development was controlled by the early structures, which possessed inheritance, directionality and newborn characteristics. The evolution of the marine basin ended basically because of the tectonic events in the end of the Carboniferous, and large continental basin began to form. The Carboniferous basins were buried, uplifted, eroded, magmatic thermal reworked, and deformed or folded during the late Hercynian, Indosinian, Yanshan and Himalayan. There are differences in the transformation of each region. Oil and gas exploration results confirmed that the Carboniferous in northern Xinjiang is important exploration strata. The highquality source rocks formed both in the Early and Late Carboniferous basin evolution. Volcanic rocks are important cap rocks and reservoirs of oil and gas. Multitransformation events not only benefitted volcanic reservoir properties, but also formed favorable hydrocarbon traps. Selfgenerated and injected reservoirs have been found in the Carboniferous. The distribution of oil and gas shows that the selfgenerated reservoirs distribute near the source. Therefore, it is of significance to strengthen the research of the evolution of basin formation, of subsidence centers and the distribution of hydrocarbon source rocks.

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    Igneous lithology identification and lithofacies classification in the basin using logging data: Taking Junggar Basin as an example.
    WANG Ze-Hua, SHU Xiao-Min, SUN Zhong-Chun, LUO Xin-Beng, DAI Xiong-Jun, DAI Yong
    2015, 22(3): 254-268. 
    DOI: 10.13745/j.esf.2015.03.022

    Abstract ( 1812 )   PDF (3541KB) ( 901 )  

    Taking the Junggar Basin as an example, this paper proposed a method for logging lithology identification and logging facies classification of igneous rock. Using the theory of igneous rocks and the technique of rock physics, we have set up the logging classification standard for igneous rock lithology and lithofacies, and revealed that the natural gamma ray logging, density logging, and ECS logging are the most sensitive logging methods to the variety of chemical components of igneous rock. We have observed that, from basic to acid igneous rock, the intensity of natural radioactivity is gradually growing, the density is reducing, the content of metal elements is reducing, and the silica content is growing. The structural change is partly reflected by natural radioactivity, density, resistivity of igneous rock. Compared with the homogeneous lava and pyroclastic rock, the intensity of radioactivity, the value of density, and the resistivity are degraded in magnitude. The most sensitive logging for igneous rock alteration degree is the compensated neutron logging, while the density and the resistivity also partly reflected the alteration degree. With the increase of the alteration degree, both the density value and the resistivity appear a tendency of declining. We have utilized the logging curves which are sensitive to lithology to make multidimensional igneous lithology identification chart. By using imaging logging, the texture and structure of igneous rock identification chart was made; the ECS logging was applied to distinguish the rock composition; and the methods were validated through the core data. A technique for igneous rock lithology recognition mode was proposed based on the conventional logging, imaging logging, ECS logging, and core calibration. Thus a way for comprehensive assessment of the type, composition, texture and structure of igneous rock has been built up; this method greatly enhances the identification accuracy for complicated igneous lithology.

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    CambrianOrdovician prototypic basin, paleogeography and petroleum of Tarim Craton.
    ZHANG Guang-E, LIU Wei, ZHANG Lei, XU Bing-Song, LI Hong-Hui, ZHANG Bao-Min, WANG Li-Dong
    2015, 22(3): 269-276. 
    DOI: 10.13745/j.esf.2015.03.023

    Abstract ( 2257 )   PDF (1545KB) ( 2440 )  

    Cambrian and Ordovician are most important marine carbonate reservoirs in the Tarim Basin. On the basis of the analysis of plate tectonic environment, deep tectonic background, sedimentary, tectonic evolution and volcano activities, we reconstructed the CambrianOrdovician prototypic basin and lithofacies paleogeography of the Tarim Basin and analyzed their relationship with oil and gas accumulation. According to main tectonic stress, Cambrian and Ordovician can be divided into two stages, which are Cambrian and Early Ordovician extensional tectonic background stage and the Middle to Late Ordovician convergent tectonic background stage, we separately researched the basin prototype and paleogeography in these two stages, and mainly focused on the formation and evolution of paleouplift and carbonate platform and the distribution of open platform and restricted platform facies, which have important impacts on the oil and gas accumulation in carbonate reservoir. We have summarized the main source rock and reservoir development models of Cambrian and Ordovician. Three types of high quality source rocks were developed in the Tarim Craton, depending on the basin type and location where the source rocks were deposited, while the reservoir can generally be separated into sedimentary reef and bank reservoir and karst reservoir. The sedimentary and karst reservoir can both be divided into four kinds. Considered the basin evolution, source rock and reservoir distribution, we proposed favorable exploration areas for marine carbonate reservoirs in the Tarim Basin.

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    Distribution and migration of the Phanerozoic palaeouplifts in the Tarim Basin, NW China.
    HE Bi-Zhu, JIAO Cun-Li, HU Zhi-Qin, CA Zhi-Hui, LIU Shi-Lin, ZHANG Jian-Xin, LI Hai-Bing, ZHANG Miao
    2015, 22(3): 277-289. 
    DOI: 10.13745/j.esf.2015.03.024

    Abstract ( 1651 )   PDF (2778KB) ( 658 )  

    The Tarim Basin is the largest superimposed basin in NW China, in which the multiple regional unconformities and palaeouplifts developed in the Phanerozoic, and both of them are closely related in their formation and evolution. In this paper, based on the seismic, drilling and outcrop data, the tectonic sequences, the structural architectures of unconformities and the accumulation minimum growth factor in basinscale are analyzed. The distribution, formation and uplifting process of palaeouplifts are better understood, especially in the Hotian, Tazhong, Tabei, Bachu, and Tadong palaeouplifts. The results suggest that the structural deformations and distributions of palaeouplifts during the main tectonic movement phases in the Tarim Basin are coordinated with the tectonism of the peripheral orogenic belts. From the Early Paleozoic to present, six times of migrations of the palaeouplifts had occurred. And each migration had changed and responded to the tectonism of the peripheral basin orogens in the same phase. According to the controlling factors of palaeouplift formation, the uplifts in this basin can be divided into four genetic types, including the fault controlled uplift, the inheritance uplift, the forebulge of the foreland basin and the tectonic palaeogeography uplift. The differential uplifting of the palaeouplifts occurring in their different parts may be significant for the oil and gas accumulation.

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    The type of prototypic basin and tectonic setting of Tarim Basin formation from Nanhua to Sinian.
    ZHOU Xiao-Bei, LI Jiang-Hai, WANG Hong-Gao, LI Wen-Shan, CHENG Ya-Lin
    2015, 22(3): 290-298. 
    DOI: 10.13745/j.esf.2015.03.025

    Abstract ( 1542 )   PDF (1591KB) ( 793 )  

    The prototype and tectonic evolution of Tarim Basin from the Nanhua to the Sinian Period are discussed based on the field observations in the northern margin of Tarim Basin and combined with seismic interpretation and comparison of drilling wells data. It is concluded that the Tarim block aggregated into Rodinia supercontinent at latest and departed from Gondwana supercontinent at the earliest, which caused that the continental rift system mainly formed in Northeast and Southwest Tarim. Neoproterozoic diamictite and multiphased igneous events impacted the whole Tarim block. The northern and southern parts of Tarim show distinct differences; the northern has undergone extensional events corresponding to the breakup of Rodinia and crustal thinning during the SinianCambrian Period and developed graben basins and Sinian strata that were gradually pinching out in the central Tarim and mainly distributed in the north as the depocenter; the south may have been the uplifterosion area for a long period, and the southern margin was possibly involved plate in marginal subduction, accretion and uplift in the late Neoproterozoic.

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    A study on paleoflora in Emuerhe Group, Mohe Basin.
    XIAO Chuan-Tao, XIE Meng, WEN Zhi-Gang, DIAO Sheng-Min, YANG Xiao-Beng, ZHANG Wen-Long
    2015, 22(3): 299-309. 
    DOI: 10.13745/j.esf.2015.03.026

    Abstract ( 1581 )   PDF (2628KB) ( 771 )  

    It is the very first time to analyze and study the paleoflora of Emuerhe Group in the research area systematically and describe the major component characteristics of each plant category. The paleoflora is composed mainly of ancient ferns and seed plants, among which, ferns amount to 8 genus 15 species, containing Filicophyta and Sphenophyta; seed plants add up to 15 genus 29 species, contain Ginkgophyta, Cycadophyta and Coniferophyta. Plant fossil assemblage of Emuerhe Group bears the following characteristics:(1)Coniopteris has high diversity and abundance; (2) the classic Coniopteris burejensis and Eboracia lobifolia in Middle Jurassic have been found; (3) the simultaneous abundant appearance of Coniopteris,Cladophlebis,Eboracia is the prime feature of the paleoflora in the area. The above characteristics indicate that the Paleoflora belongs to the late ConiopterisPhoenicopsis flora in Middle Jurassic. According to the comprehensive analysis on longitudinal distribution and combined features of the paleoflora in Emuerhe Group, the late flora combination ConiopterisPhoenicopsis can be divided into 3 subcombinations which are ConiopterisNilssonia in Xiufeng Formation, ConiopterisCzekanowskia in Ershierzhan Formation and Coniopteris burejensisCladophlebis cf.asiatica in Mohe FormationKaikukang Formation. The study on paleoflora in Emuerhe Group not merely enriches the biostratigraphic data in the study area and identifies the geological age of Emuerhe Group which belongs to the Middle Jurassic,but more importantly solves the current basic geological problem of exploration of gas hydrate.

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    Reservoir characteristics and main control factors of the Carboniferous Huanglong Formation in Sichuan Basin.
    HU Meng-Yi, DENG Meng, HU Zhong-Gui, XUE Dan
    2015, 22(3): 310-321. 
    DOI: 10.13745/j.esf.2015.03.027

    Abstract ( 1589 )   PDF (2246KB) ( 698 )  

    Carboniferous Huanglong Formation is the main producing formation of gas reservoir in the Sichuan Basin. Through years of exploration and development work, it has entered the stratigraphiclithologic gas pool exploration stage. Therefore, it is especially important to strengthen the research of the reservoir characteristics and distribution prediction in the study area. Based on abundant core observation and thin section analysis, combined with the SEM, reservoir physics and pore texture research, this paper analyzes the reservoir development characteristics and main control factors and predicts the potential reservoir distribution area. Studies show that Carboniferous Huanglong Formation in the Sichuan Basin developed restricted platform supratidal flatintertidal flatsubtidal flat; among them, the intertidal flatsubtidal flat shallow shoal microfacies were developed; the dominant lithologic units are grain dolomite (or its remnant), crystalline powdercryptomere dolomite and dolomitic karst breccias; The noticeable reservoir spaces are intercrystalline pore and intercrystalline dissolved pore, while the secondary pore types are intergranular dissolved pores, intragranular dissolved pores, moldic pores and fractures; the porosity of Huanglong Formation ranges from 0.03% to 30.67%, average 2.59%, while the permeability ranges from 0.001 μm2 to 290×10-3 μm2, average 1.56×10-3 μm2. The reservoir of Huanglong Formation is characterized by low porosity and extremely low permeability, as well as a relative good correlation between porosity and permeability, belonging to crackpore reservoir; the porethroat assemblages are dominated by small pore and mediumfine throat. The potential reservoir is controlled by lithology, sedimentary facies and late stage diagenesis; the reservoir physics of grain dolomite in shallow shoal microfacies and of crystalline dolomite in tidal flat facies are better; sedimentary microfacies controlled the distribution range and scale of reservoir; deuteric dolomitization is the foundation of reservoir formation, it is characterized by multistages and multicauses; among all of the dolomitization stages, the penecontemporaneous and early diagenetic dolomitization are most beneficial to the formation of potential reservoir; paleokarst events could enlarge the reservoir scales, and its zonation, the fluid hydrodynamic condition and lithology in different dissolution, and microtopography are the direct control factors of karst reservoir spatial distribution patterns and development scales; paleokarst events are the key to improving the quality of reservoir. According to the dolomite thickness map, dolomitic karst breccias map and reservoir porosity map, we chose the contour lines that exceed 3% as a constraint boundary, predicted the lebensraum of potential reservoir in the Sichuan Basin, and among them, we have evaluated 7 reservoirs in rank I, and 5 in rankⅡ. The results abovementioned have important effects on the reservoir anticipation and gas prospecting in the Sichuan Basin.

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    Research of simulated experiment on gravity flow deposits of tight sand bodies of Chang 7 Formation in Longdong area, Ordos Basin.
    YANG Hua, NIU Xiao-Bing, LUO Shun-She, FENG Qing-Bin, LV Ai-Ai
    2015, 22(3): 322-332. 
    DOI: 10.13745/j.esf.2015.03.028

    Abstract ( 1699 )   PDF (2214KB) ( 768 )  

    Tight sandstone has been an important field of exploration and development of oil and gas in China recently. The tight sandstones of Chang 7 Formation of Longdong area in Ordos Basin mainly developed into braid deltas and gravity flow sedimental sand bodies. And the latter has great potential in exploration and development. On the basis of research of regional structure, paleoclimate, ancient landform and sedimentary systems, we applied the technology of sedimentary simulation to recreating the formation processes and main controlling factors of the researched area, the Chang 7 Formation. Under laboratory conditions, sedimentary facies of semideep to deep lakes are mostly sandy debris flow, turbidite and deep lake mud. The experimental research indicates that the main controlling factors to impact the formation and evolution of gravity flow sedimental sand bodies are: (1)sediment concentration (decides the sediment type of gravity flow); (2)the shape of the bottom of a lake basin (controls the distribution of sand body of gravity flow); (3)the lake stage and flow rate (decide the sedimentary thickness and the scale of gravity flow); (4)the intersection of various sources (decides the transverse connection of gravity flow). Also, by analyzing and comparing the results of the experiment, we predicted the areas with favorable reservoir distribution. We combined the original geological model of Longdong area with the results of the simulated experiment and established the sedimentary pattern of Chang 7 Formation of the Triassic in Longdong area under the condition of sedimentary simulation experiment.

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    Fluid dynamics model of mafic magma metallogenic system in Panxi Area.
    HEI Hui-Xin, LUO Zhao-Hua, CHENG Jin-Hua, QIU Yi-Dan, DENG Dun-Feng, LI Jie, I.V.Vikentyev
    2015, 22(3): 333-347. 
    DOI: 10.13745/j.esf.2015.03.029

    Abstract ( 1545 )   PDF (2556KB) ( 761 )  

    Despite of special attentions drawn to mafic intrusions and their relations to mineralization, many scientific issues related to them remain in ambiguity till now. Based on the new field observations and the theoretical analysis, a complexity fluid dynamic model is proposed to attempt an integrated interpretation of ore deposit geology, petrography, and mineralogy of the magmatic iron deposit. Given the behavior of a magmatic mineral system being decided by strong interactions between the melt and fluidsubsystem, the successive changes of physical properties of the system would induce a variety of nonlinear modification in the system. (1) Before that there is not significant crystallization in the meltsubsystem, the orebearing fluid migrates up through the pervasive percolation, and induces oreinduced intrusion with hidden igneous layering and concordant ore bodies with disseminated structure. In such a condition, the orebearing fluid migrating up in a high speed could result in mineralization in the whole magmatic intrusion. The orebearing fluid migrating up with a lower speed could also lead to intense differentiation of a magmatic body, but the oreforming metals will not be concentrated to the marginal parts of the intrusion. (2) If the intrusion is consolidated partly (for instance, a half), the orebearing fluid may be transported on large scale only to the unconsolidated centre of the intrusion, in which the doublediffuse convection is caused, and obvious rhythmic sequences and concordant massive ore bodies are produced. (3) When the magmatic intrusion is cooled to complete consolidation, if the fluid overpressure is high enough or the farfield stress field is in action, the consolidating intrusion will be ruptured near the previous conduits. Under such circumstances, the orebearing fluid ascend to form the discordant ore body. (4) After complete consolidation of magma intrusion, subsequent invasion ore fluid can migrate along the contact zone between the layered intrusions and the country rock in the bottom, forming a new type of tabular ore or ore nests, even skarn ore bodies. (5)Sulfiderich fluid may also ascend in succession with the oxiderich fluid, facilitating the generation of sulfide ore body. This analysis is broadly in line with the actual situation in Panxi, and thus it can be a conclusion can be drawn. (1) Whether the magma intrusions become ore intrusions depend on the input of ore fluid, rather than magmatic differentiation. (2) Differential characteristics of ore intrusions are the results of the ore fluid input, rather than the causes.(3)Mafic magmatic system is a complex dynamic system. Ore fluid input is the root cause of its nonlinear behavior change. (4)The Metallogenic system of mafic magma in Panxi include concordanttype (including massive subtype and disseminated subtype two subtypes), discordanttype, skarntype iron ore subsystem, disseminated and massive sulfide mineralization subsystem. (5) In Panxi area, iron ore body is not only located in the layered rock, exploration potential also resides in the country rock underlain. There is even potential to discovering massive sulfides.

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    RbSr dating of sphalerites from Dongjun PbZnAg deposit, Inner Mongolia and its geological significance.
    YANG Yun-Cheng, GUO Mo-Jun, WANG E-Jun, SHE Hong-Quan, LI Jin-Wen, ZHANG Bin
    2015, 22(3): 348-356. 
    DOI: 10.13745/j.esf.2015.03.030

    Abstract ( 1401 )   PDF (1327KB) ( 3862 )  

    Hydrothermal vein type of PbZn polymetallic ore deposits is one kind of important deposit in Deerbugan meatallogenic zone, Inner Mongolia, China. Their oreforming ages and geological backgrounds are still unclear. Six pieces of sphalerites collected from Dongjun hydrothermal vein type of PbZnAg deposits were analyzed for Rb, Sr and their isotopes. The 87Rb/86Sr and 87Sr/86Sr ratios fall into the ranges of 0.2838 to 6.5030 and 0.713685 to 0.725241, respectively, and they show good linear relationship, defining a RbSr age of 130.2±4.4 Ma (2σ, MSWD=16), (87Sr/86Sr)0=0.713176±0.000057, indicating that the mineralization age of Dongjun PbZnAg deposit is in the Early Cretaceous. As the Da Hinggan Mountains and its adjacent region were in an extensional setting in the early Cretaceous, so this type of ore deposit was formed in an extensional tectonic regime in the early Cretaceous, and its mineralization was related to hypabyssalultra hypabyssal magmatic intrusion. This type of ore deposit represents an important metallogenic period and type in the Deerbugan metallogenic belt.

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    Petrogenesis and metallogeny of Yinkeng porphyry Mo deposit in Jinhua, Zhejiang: The evidence from the petrology, petrogeochemistry, isotopes and SHRIMP zircon UPb dating.
    WANG Ke-Jiang, ZHANG De-Hui, WANG Chen-Sheng, YI Xian-Bei, SHU Yu-Di, FU Fen
    2015, 22(3): 357-367. 
    DOI: 10.13745/j.esf.2015.03.031

    Abstract ( 1595 )   PDF (1820KB) ( 743 )  

    Yinkeng porphyry Mo deposit is located in the east of JiangshanShaoxing suture zone. The veinletdisseminated type of Mo mineralization occurred in the interior of porphyry granite. The orebearing granite was classified as Atype granite with high silica and alkaili content, strong fractionation and medium to weak peraluminous. The REE model appears “V” shape, and the enrichment of LREE is obvious with an obvious negative Eu anomalies. The granite is richer in Rb, Th, K, U, La, Ce, Pb and poorer in Ti, P, Nb, Ta, Zr, Hf. The sulfur originated mainly from magma. The metallogenic fluids comprised water and a small amount of CO2, CH4 and CO2-3, which seemed to be mixed with aqueous magma vapour and meteoric water. Orebearing porphyry has relatively high ISr(0.710910.71477) and low εNd(t)(-7.2-1.8)value, which suggests that the source rock of porphyry possibly originated from EarlyProterozoic bed rock. The mean age of Yinkeng deposit is 110.1±1.5 Ma. Research shows that the magma closely related to mineralization occurred in extensional setting. The source region of magma is the lower crust and may have been contaminated by mantle materials. The magma intrusion happened after the transition of Ancient Tethys to Pacific tectonic domain of South China, in the period of lithospheric territorial expansion.

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    Fluid evolution and mineralization of Hangjinqi sandstonetype uranium deposit, Ordos Basin.
    ZHANG Long, LIU Che-Xiang, DIAO Zhong-Beng, WANG Fei-Fei, SONG Zi-Sheng
    2015, 22(3): 368-381. 
    DOI: 10.13745/j.esf.2015.03.032

    Abstract ( 1602 )   PDF (2359KB) ( 807 )  

    Uraniumbearing sandstone diagenesis is a complicated process in the Middle Jurassic Zhiluo Formation, north of Ordos Basin, and mineralization is inconsistent with typical interlayer redox model. On the basis of the study of diagenetic minerals, stable isotope composition (δ13C and δ18O) of calcite cements and fluid inclusions in Hangjinqi uranium deposit, north of Ordos Basin, we discussed the features of fluid activities and the process of uranium mineralization. The result shows that three fluid types were identified in the uraniumbearing sandstone: oxidizing meteoric water, acidic fluid generated by biodegradation of hydrocarbon, and alkaline hydrothermal fluid. The peak homogenization temperatures of primary aqueous inclusions trapped in sparry calcite are 140160 ℃, with the salinities ranging from 8.00% to 16.34%. The sparry calcite in sandstone has negative values of δ13C between -7.1‰ to -18.3‰(PDB). These data indicate that hightemperature, highsalinity and hydrocarbon related fluid occurred at the late stage of fluid evolution history. Previous studies have proved bacterial activity caused the uranium reduction in Zhiluo Formation sandstonehosted deposit, north of Ordos basin. However, such bacterial activity cannot occur in the hightemperature environment. Considering the uranium mobility characteristics in groundwater, we concluded that hydrothermal fluid activity was not contradictory with the microbial reduction of uranium. Hightemperature alkaline fluid changed the physicochemical condition of fluid environment, which facilitated the formation of stable CaU(VI)CO3 complex, enriching the concentration of soluble uranium in solution. Bacteria exerted the reduction of the uranium after the hydrothermal fluidrock interaction.

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    Practice and exploration of 1∶50000 geological mapping in accretionary complex belt: An example from Qomo Ri area of Central Qiangtang, Tibet.
    MAO Xiao-Chang, WANG Gen-Hou, LIANG Xiao, ZHANG Feng, LIU Xiang, LIU Jun-Beng, ZHENG Yi-Long
    2015, 22(3): 382-393. 
    DOI: 10.13745/j.esf.2015.03.033

    Abstract ( 1321 )   PDF (2274KB) ( 822 )  

    The theory and method for 1∶50000 geological mapping in accretionary complex belt is a focus problem for present regional geological surveys. Based on 1∶50000 geological mapping, the characteristics of lithologies, collage style and structural framework for accretionary complex can be easily found, which then contributes to the knowledge of tectonic evolution in suture zone. After 1∶50000 geological mapping and 1∶10000 structurelithology mapping in Qomo Ri Indosinian accretionary complex in Central Qiangtang, it is discovered that this complex is comprised of intensivecleavaged matrix and tectonic blocks that weld each other by brittle, brittleductile and ductile shear faults forming at the oceanic subduction stage. The matrix are composed of fine plastic rocks from submarine fans, continental slope turbidite and deep ocean deposit, and also other strongly foliated rocks. Tectonic blocks mainly contain OIBtype ophiolite relics, mafic dike relics, seamount carbonate rock relics, exotic block relics etc. This complex is characterized by a stable regional foliation S2 of CCCtype, forming under a compressional background following oceanic subduction. It is also superimposed by postorogenic shallow level deformations showed by nonpenetrative foliation S3. The geological maps are expressed by means of a method named “threecomponent” and “fourfactor”. The above practice presents methods including outcrop observation, mapping unit classification, and graphic expression of map for 1∶50000 geological mapping in accretionary complex, which also provides implications for the present geological mappings in orogenic belt.

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    Acoustic emission characteristics of watersaturated coals under triaxial stress condition in the process of deformation and failure.
    CA Yi-Dong, LIU Da-Meng, TAO Yan-Bin, LI Dun-Gan, QIU Yong-Kai, ZHANG Bai-Ren
    2015, 22(3): 394-401. 
    DOI: 10.13745/j.esf.2015.03.034

    Abstract ( 1577 )   PDF (1315KB) ( 643 )  

    Experiments on acoustic emission (AE) of coals with saturated water under triaxial stress were conducted, and the relationship between stress and strength under triaxial stress was analyzed on the rock mechanical experimental rig (GAW2000). The results reveal that the coals of different ranks always have variable AE characteristics. Normally, they were divided into three types. The results of triaxial experiments and AE analysis of watersaturated coals show that AE events were less active at the elastic stage, after that the AE become active; Experimental comparison between uniaxial and triaxial shows that the confining pressure will significantly change the strength of semianthracite coal at the compaction stage, while it is not obvious for anthracite coal. And the confining pressure is insignificant for other stages of coal deformation and failure process. AE ring counts and energy counts reveal that they can be applied to predicting the coming failure point. The frequency and amplitude of the ringing rate and energy rate have been greatly raised during approaching the destruction precursor for the semianthracite coal. When the stress reaches 90% of the yield stress, the ring counts and energy counts will remain unchanged. For anthracite coal, the destruction precursor will produce an obvious sharp increase in frequency or amplitude. Meanwhile, the results also reveal that AE characteristics have significant relationship with coal composition and coalification.

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    Exchange flux of mercury on soil/air interface in black soils of Heilongjiang Province.
    LIU Fei, CHENG Hang-Xin, YANG Ke, DIAO Chuan-Dong, BANG Min, LI Kuo, LIU Ying-Han
    2015, 22(3): 402-410. 
    DOI: 10.13745/j.esf.2015.03.035

    Abstract ( 1698 )   PDF (1160KB) ( 1037 )  

    The mercury fluxes through soil/air interface monitoring were conducted in black soils in Heilongjiang field, using a dynamic flux chamber coupled with a Tekran 2537 B Ambient Mercury Vapor Analyzer. The average value of the mercury fluxes through soil/air interfaces in seven studied suites was 69.46±37.08 ng?m-2?h-1, which was close to that measured in cities of China. The effects of environmental factors on the mercury fluxes were analyzed. The soil mercury concentration affected the releasing ability of Hg of soils. The mercury exchange fluxes showed significantly positive correlations with total solar radiation intension, soil temperature, soil moisture and wind speed, significantly negative correlation with the relative humidity, and no correlation with atmospheric pressure.

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