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ABSTRACT: Relationship Between Tectonics and Hydrocarbon Systems Development in Xinjiang Uygur Autonomous Region, Western China


Recent Chinese exploration successes in the Tarim basin have focused worldwide interest on the Xinjiang area. Regionally, basins are underlain by amalgamated ophiolites, blueschists, arc terranes, metasediments, and continental blocks. Consolidation with the stable Siberian craton began in the middle Paleozoic with the accretion of trapped oceanic crust and island arc terranes (e.g., Junggar). Late Paleozoic/early Triassic collisions added the Yili, Tian Shan, Tarim, and Qaidam blocks. The late Carboniferous accretion of the large Tarim micro-continent marked the beginning of a series of Meso-Cenozoic collisions of rifted, southern-hemispheric blocks onto Eurasia, culminating with the arrival of the Indian plate in the Eocene. The structure and strata of the resultant successor basins point to relationships between this tectonic evolution and hydrocarbon system development. The tectonic history not only created traps, but also profoundly influenced the depositional, burial, and diagenetic histories of source, reservoir, and seal units. For example, the late Paleozoic uplift of the Tian Shan block effectively shielded the subsiding Junggar basin from marine conditions, so that rich, thick, lacustrine source rocks were deposited and preserved. The paleo-Tian Shan may have provided an orographic effect on local climate, resulting in a higher precipitation rate in the Junggar basin. In the Tarim basin, the reservoir quality of productive, lower Paleozoic, platformal carbonates was enhanced by fracturing and leaching processes below collision induced angular unconformities Similar rocks were intensely folded in the Qaidam basin. Episodic block collisions produced varied, repetitive tectono-stratigraphic response within the Xinjiang basins, locally affecting the development or demise of hydrocarbon systems.


AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)