Geometry And Kinematics Of The Western Part Of Southwest Tarim Basin

Based on the Theory of Fault-related Fold and other theories of StructuralGeology, combining data of surface geology, seismic profile, remote sensing, DEMand drilling, this paper gives a fine interpretation of the Sugaite Anticline, YingjishaAnticline and Bashituopu Anticline, so as to identify the geometry and kinematics ofthese three structures. This paper tries to disclose the tectonic evolvementcharacteristics of the western part of Southwest Depression of Tarim Basin，including the changing of tectonic style from the West Kunlun Mountains to the basinand the tectonic time sequence. This paper also focuses on analyzing the impact of thetectonic evolvement on hydrocarbon reservoir, with the purpose of setting an examplefor the future hydrocarbon exploration. The paper has reached the followingconclusions:1）The formation of Bashituopu Anticline includes three stages. First, from LateCarboniferous to Permian, under the influence of late Hercynian Tectonic movement,fault bend fold and fault propagation fold were formed along the Bashituopu Fault.Second, during Miocene, with the strong thrust and uplifting of the Bachu Uplift, thewhole Maigaiti Slope dipped southwards, while the north limb of BashituopuAnticline was raised, with minor detachment in the basement. Third, duringPleistocene, the Cenozoic strata formed a broad fault detachment fold along thegypsum and mudstone on the bottom of Paleogene.2）The formation of Yingjisha Anticline includes two stages. First, because of thedetachment of the basement, all the strata from Proterozoic to Cenozoic were folded,forming the early anticline at the place where Yingjisha Anticline currently is. Second,form Pleistocene, with the thrust of West Kunlun Mountains, the south dipping deepfault F1and the north dipping shallow fault F2were formed in the Yingjisha Anticline.Deep anticline and shallow anticline were also formed under the influence of F1andF2respectively.3）The formation of Sugaite Anticline includes two stages. First, because of thedetachment of the basement, all the strata from Proterozoic to Cenozoic were folded, forming the early anticline at the place where Sugaite Anticline currently is. Second,from Pliocene, with the thrust of West Kunlun Mountains, a typical triangle zone wasformed in the Sugaite Anticline. Tectonic intensity changes along the long axis of theanticline. The strongest tectonic movement is in the middle part, where the trianglezone formed the earliest, with the largest shortening amount, decreasing toward bothsides.4）The tectonic and sedimentary evolution of the western part of SouthwestDepression of Tarim Basin underwent five major tectonic movements: Middle to LateCaledonian Movement, Early Hercynian Movement, Late Hercynian Movement,Indo-China and Yanshan Movement as well as Himalayan Movement. Thenorth-south uplifting of the Maigaiti Slope during Late Triassic destroyed the earlyformed reservoirs, leading to the redistribution of hydrocarbons in the studied area.Since Cenozoic, especially under the influence of the tectonic movement of LateHimalayan Movement, lots of traps formed in front of the mountains, with goodhydrocarbon migration conditions, making the area very prospective for hydrocarbonresources exploration.