Stratigraphical And Structural Analyses Of The Altyn Slope Area Western Qaidam Basin

The western area of Qaidam basin (western Qaidam basin) is the main oil-enriched region in Qaidam basin confined by the Altyn and Kunlun Mountain orogenic belts, whose tectonics development and evolvement basin's are influenced by the Altyn strike-slip fault in the north and the Northern Kunlun Margin Fault in the south, its tectonics and deformations is quite complicated. The stratigraphic sequence and the tectonics' framework of this area are controversial for a long time, which hampered the prospecting and exploitation of oil-gas resource severely.In this paper, the author regards the Altyn orogenic belt and Qaidam Basin as a uniform study object. Based on the theories of tectonics geology, sedimentology, the stratigraphy of stratum sequence, etc , and synthesized Geology, Seism, well-logging methods and so on, the author analysis and study the stratum and tectonics' characteristics of western Qaidam basin in detail.(1) Taking whole basin standard stratum description as foundation, analyzes Qigequan and Ganchaigou sections' characteristics of this area, determined the stratum' time anew. According to the division principle of deposition-structure sequence, divides this area into 2 first-grade stratum sequences, 12 second- grade stratum sequences,56 third- grade stratum sequences.(2) Through seism section plane's link-piece explanation, division principle of second- grade tectonic unit is decided, then from the southwest to northeast, this area is divided into 4 second- grade tectonic units: thrust-fold belt of Qigequan-Hongliuquan; Slianting-slip thrust organic belt of North Ahati-Ganchaigou; thrust beltbefore the extrusive wedge of Xianshuiquan-Honggouzi;thrust-overlap belt of Yueyashan.(3) According to the analysis on tectonics kinematics, combined with plate tectonics theory and basin-mountain coupling theory, analyzes the properties of basin boundaries systemly: thrust basin boundary in the North of Ahati-Ganchaigou area and in the south of Quanyagou area, which is controled by the compress slanting-slip tectonics from Eocene;overlap-compress thrust basin boundary in the Hongliuquan-Qigequan and Honggouzi-Yueyashan,which is controled by the compress-thrust function of Altyn from Paleocene(4) Using the "Produce,Store,Cover,Enclose,Transport,Conservation" threory to estimate oil-gas resource, concluded that there has two kinds of oil-gas storing boundary by strike-slip thrust orogenic belt of north Ahati-Ganchaigou as boundary, there are two sets of oil-gas storing, one is deep and the other is shallow: the deep one is original(E-N₁), the shallow one is hypo-produced (N₂) .The results indicate that western Qaidam basin has a great prospecting potential .And then , reasonable explaining the stratum and tectonics ' characteristics of western Qaidam basin is of important significance to the oil-gas exploitation of western Qaidam basin.