Tectonic Evolution of Tarim Basin in Cambrian-Ordovician and the Implication for Reservoir Development

Yu, Bingsong; Li, Juan

Tarim Plate in China, with crystalline basement of Pre-Neoproterozoic, is situated between Tianshan and Kunlun orogenic zones. The Tarim Plate includes the stable area of Tarim basin and the surrounding multi-stage marginal activity belts. It is confined by suture zone of South Tianshan (South Tianshan tectonic belt) as north boundary, Kangxiwar suture zone (Kunlun orogenic belt) as the southwest boundary and Altyn fault zone (Altyn orogenic belt) as the southeast boundar, respectively. In order to search after the control of regional tectonic evolution surrounding the Tarim basin on the inside distribution of sedimentary facies and reservoir development, based on the research of tectonic evolution of southern Tianshan and western Kunlun orogens, the geodynamic setting of Tarim basin has been investigated, and it can be seen that the extension around the Tarim plate began at the Later Precambrian and generated southern Tianshan Ocean at the north and western Kunlun Ocean at the southwest, also the Altyn Ocean at the southeast, and the subduction of the southern Tianshan Ocean in the eastern section and that of the western Kunlun Ocean started at the Early Ordovician. From this, we can conclude that the geodynamic reversion from extension to convergence around the Tarim plate began at the Early Ordovician, which results in a series of depositional response inside the basin, including (1) fast filling of Manjia'er aulacogen; (2) formation of paleo-uplifts; (3) obvious differentiation of the paleogeomorphic framework and the change of distribution of platform marginal high energy facies belts; (4) the conversion of sedimentary base level, which was accompanied by the according change of lithology from dolomite to limestone; (5) development of many unconformity surfaces in the Ordovician System. These sedimentary responses not only controlled the spatial distribution and migration of favorable carbonate reservoir facies belts, but also created conditions for the development of karstification. The carbonate reef and bank reservoirs are favorably distributed along the east margin of carbonate platform facing the Manjia'er depression to the east in the Cambrian and the Lower Ordovician with the extensional dynamic setting, and distributed around the paleo-uplifts in the Middle and Late Ordovician with the convergent dynamic setting. The favorable karst reservoirs in the Middle and Lower Ordovician are developed in the paleo-uplift highland and paleo-slope zone.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013