1. China Aero Geophysical Survey and Remote Sensing Center for Natural Resources,Beijing 100083,China 2. School of Earth Science,Zhejiang University,Hangzhou 310012,China 3. Research Center of Structures in Oil and Gas Bearing Basins,Ministry of Education,Hangzhou 310012,China
Based on 2D and 3D seismic data, this study analyzes the geometric characteristics,horizontal shortening,and active time of the Alar fault in the southwestern Qaidam Basin in detail and explores the kinematic characteristics,formation mechanisms,and significance for hydrocarbon accumulation during the whole Cenozoic.The results are as follows.The Alar fault can be divided into the western segment in NWW trending and the eastern segment in nearly NS trending,which are nearly vertical. As shown in sections,the western segment inclines southward with a relatively small dip angle,while the eastern segment inclines westward with an almost vertical section.The Alar fault has been active since the Early Cenozoic.The activities of the western segment are dominated by thrust,with horizontal shortening and vertical uplift both exceeding 3 km and strike-slip motion for about 1 km.The activities in the eastern segment are dominated by dextral strike-slip motion,with horizontal shortening and vertical uplift of about 1 km and strike-slip motion of up to 3 km.The formation and activities of the Alar fault are jointly affected by the northward compression imposed by the Qimantage orogenic belt to the south and the Altun left-literal strike-slip fault to the west.There is a close spatial-temporal matching relationship between the fault activities and the formation of oil and gas in the southwestern Qaidam Basin.Therefore,the fault activities are of great significance for the formation of oil reservoirs.
Guan P, Jian X. The Cenozoic sedimentary record in Qaidam Basin and its implications for tectonic evolution of the Northern Tibetan Plateau[J]. Acta Sedimentologica Sinica, 2013, 31(5):824-833.
[5]
Zhou J, Xu F, Wang T, et al. Cenozoic deformation history of the Qaidam Basin,NW China:Results from cross-section restoration and implications for Qinghai-Tibet Plateau tectonics[J]. Earth and Planetary Science Letters, 2006, 243(1-2):195-210.
doi: 10.1016/j.epsl.2005.11.033
[6]
Wei Y, Xiao A, Wu L, et al. Temporal and spatial patterns of Cenozoic deformation across the Qaidam Basin,Northern Tibetan Plateau[J]. Terra Nova, 2016, 28(6):409-418.
doi: 10.1111/ter.2016.28.issue-6
[7]
Wu L, Xiao A, Ma D, et al. Cenozoic fault systems in southwest Qaidam Basin, northeastern Tibetan Plateau:Geometry,temporal development,and significance for hydrocarbon accumulation[J]. AAPG Bulletin, 2014, 98(6):1213-1234.
doi: 10.1306/11131313087
Cui X B. The application of the integrated exploration technique to the western part of qaidam basin[J]. Geophysical and Geochemical Exploration, 2003, 27(3):171-175.
Xiong Y G, Luo Z, Zhang Q Q, et al. Overthrust belt forward analysis and interpretation:A case study of Yingxiongling area[J]. Geophysical and Geochemical Exploration, 2019, 43(3):551-557.
[10]
Mao L, Xiao A, Wu L, et al. Cenozoic tectonic and sedimentary evolution of southern Qaidam Basin,NE Tibetan Plateau and its implication for the rejuvenation of Eastern Kunlun Mountains[J]. Science China Earth Sciences, 2014, 57(11):2726-2739.
doi: 10.1007/s11430-014-4951-z
Ni J L, Wang J C, Zhou L, et al. Study on the Tectonic events of East-Kunlun Orogenic Belt and Prototype about West-South Qaidam Basin during Mesozoic and Cenizoic[J]. Geoscience, 2007, 21(3):505-510.
[12]
Xiang C, Fu S, Wang H, et al. Geometry and kinematics of the Arlar strike-slip fault,SW Qaidam basin,China:New insights from 3-D seismic data[J]. Journal of Asian Earth Sciences, 2015, 98:198-208.
doi: 10.1016/j.jseaes.2014.09.039
Li L B, Sun L N, Sun J Z, et al. The fracture characteristic analysis in Southwest area of Qaidam Basin[J]. Oil Geophysical Prospecting, 2010, 45(3):443-447.
[15]
Chen W P, Chen C Y, L N A Belek J. Present-day deformation of the Qaidam basin with implications for intra-continental tectonics[J]. Tectonophysics, 1999, 305(1-3):165-181.
doi: 10.1016/S0040-1951(99)00006-2
[16]
Wang Y, Zheng J, Zhang W, et al. Cenozoic uplift of the Tibetan Plateau:Evidence from the tectonic-sedimentary evolution of the western Qaidam Basin[J]. Geoscience Frontiers, 2012, 3(2):175-187.
doi: 10.1016/j.gsf.2011.11.005
[17]
Wang Y, Nie J, Zhang T, et al. Cenozoic tectonic evolution in the western Qaidam Basin inferred from subsurface data[J]. Geosciences Journal, 2010, 14(4):335-344.
doi: 10.1007/s12303-010-0033-1
Wang Y D, Zhang T, Chi Y P, et al. Cenozoic uplift of the Tibetan Plateau:Evidence from tectonic-sedimentary evolution of the Western Qaidam Basin[J]. Earth Science Frontiers, 2011, 18(3):141-150.
Fang X, Jiang B, Zhang Y S. Faulted structure and hydrocarbon accumulation in western Qaidam basin[J]. Oil and Gas Geology, 2006, 27(1):56-61.
[20]
Cheng F, Jolivet M, Fu S, et al. Northward growth of the Qimen Tagh Range:A new model accounting for the Late Neogene strike-slip deformation of the SW Qaidam Basin[J]. Tectonophysics, 2014, 632:32-47.
doi: 10.1016/j.tecto.2014.05.034
[21]
Meng Q R, Fang X. Cenozoic tectonic development of the Qaidam Basin in the northeastern Tibetan Plateau[J]. Geological Society of America Special Papers, 2008, 444:1-24.
[22]
Yin A, Dang Y, Zhang M, et al. Cenozoic tectonic evolution of Qaidam basin and its surrounding regions (part 2):Wedge tectonics in southern Qaidam basin and the Eastern Kunlun Range[J]. Geological Society of America Special Papers, 2007, 433:369-390.
[23]
Yin A, Dang Y Q, Zhang M, et al. Cenozoic tectonic evolution of the Qaidam basin and its surrounding regions (Part 3):Structural geology,sedimentation,and regional tectonic reconstruction[J]. Geological Society of America Bulletin, 2008, 120(7-8):847-876.
doi: 10.1130/B26232.1
[24]
陈海清. 柴达木盆地柴西南三维区岩性地层圈闭识别技术研究[D]. 青岛:中国海洋大学, 2010.
[24]
Chen H Q. A research on the techniques for identifying lithologic stratigraphic traps in the Southwest 3D survey of Chaidamu Basin[D]. Qingdao:Ocean University of China, 2010.
[25]
Ji J L, Zhang K X, Clift P D, et al. High-resolution magnetostratigraphic study of the Paleogene-Neogene strata in the Northern Qaidam Basin:Implications for the growth of the Northeastern Tibetan Plateau[J]. Gondwana Research, 2017, 46:141-155.
doi: 10.1016/j.gr.2017.02.015
[26]
Sun Z, Yang Z, Pei J, et al. Magnetostratigraphy of Paleogene sediments from northern Qaidam Basin,China:Implications for tectonic uplift and block rotation in northern Tibetan plateau[J]. Earth and Planetary Science Letters, 2005, 237(3-4):635-646.
doi: 10.1016/j.epsl.2005.07.007
[27]
Lu H, Xiong S. Magnetostratigraphy of the Dahonggou section,northern Qaidam Basin and its bearing on Cenozoic tectonic evolution of the Qilian Shan and Altyn Tagh Fault[J]. Earth and Planetary Science Letters, 2009, 288(3-4):539-550.
doi: 10.1016/j.epsl.2009.10.016
[28]
Fang X, Zhang W, Meng Q, et al. High-resolution magnetostratigraphy of the Neogene Huaitoutala section in the eastern Qaidam Basin on the NE Tibetan Plateau,Qinghai Province,China and its implication on tectonic uplift of the NE Tibetan Plateau[J]. Earth and Planetary Science Letters, 2007, 258(1-2):293-306.
doi: 10.1016/j.epsl.2007.03.042
[29]
徐波. 运用地震属性研究柴达木盆地早新生代断裂特征[D]. 杭州:浙江大学, 2013.
[29]
Xu B. Fault characteristics of the Qaidam Basin in early Cenozoic from seismic attributes analysis[D]. Hangzhou:Zheng Jiang University, 2013.
[30]
Wu L, Xiao A, Wang L, et al. EW-trending uplifts along the southern side of the central segment of the Altyn Tagh Fault,NW China: Insight into the rising mechanism of the Altyn Mountain during the Cenozoic[J]. Science China Earth Sciences, 2012, 55(6):926-939.
doi: 10.1007/s11430-012-4402-7
Mao L G, Xiao A C, Wang L, et al. Uplift of NW margin of Qaidam Basin in the Late Eocene:Implications for the initiation of Altyn Fault[J]. Acta Petrologica Sinica, 2013, 29(8):2876-2882.
[32]
Qiu N S. Tectono-thermal evolution of the Qaidam Basin,China:Evidence from Ro and apatite fission track data[J]. Petroleum Geoscience, 2002, 8(3):279-285.
doi: 10.1144/petgeo.8.3.279
Luo Q, Pang X Q. Application of fault control hydrocarbon theory to realize a great breakthrough of petroleum exploration in Qaidam basin[J]. Acta Petrolei Sinica, 2003, 24(2):24-29.
[34]
Pang X Q, Li Y X, Jiang Z X. Key geological controls on migration and accumulation for hydrocarbons derived from mature source rocks in Qaidam Basin[J]. Journal of Petroleum Science and Engineering, 2004, 41(1):79-95.
doi: 10.1016/S0920-4105(03)00145-1
[35]
Zeng L, Tang X, Wang T, et al. The influence of fracture cements in tight Paleogene saline lacustrine carbonate reservoirs,western Qaidam Basin,northwest China[J]. AAPG Bulletin, 2012, 96(11):2003-2017.
doi: 10.1306/04181211090