Meso-Cenozoic Tectonic Evolvement and Oil Gas Accumulation in Qaidam Foreland Basin, China

Zhao, Fan

According to regional field geological surveying, seismic stratigraphy and wellbore data, the basement features of Qaidam basin were researched, which had dual characteristics of Paleozoic fold and Proterozoic crystalline basement. The process of basin subsidence and structural evolvement was preferably consistent with structural dynamics of the collision and matching between land blocks in time, which showed nearly every phase of structural cycles was related to crustal rifting action, oceanic crustal subduction and collision between land blocks.

All of the research above represented that Qaidam foreland basin underwent four different evolvement phases, which were as follows: Stage 1, fault basin with earth crust extension formed caused by variable movements between blocks in early-middle Jurassic; Stage 2, the early extension basin was reversed and flexural basin formed under the extrusion status due to part of oceanic crustal closing and the collision between adjacent blocks from late Jurassic to early Cretaceous; Stage 3, the integrally stable and slow subsidence occurred in Qaidam basin from late Cretaceous to Eocene, when Neo-Tethys extension tectonic movement caused lithosphere extension in the area of Central Asia and northwest China. Stage 4, Qaidam block was under obvious extrusion and uplifting status by strong collision between India and Eurasia mainland, and the present geological structure of foreland basin was formed from Oligocene to now.

At last, the relationship between basin structural evolvement and hydrocarbon accumulation was illustrated, using which considerable effect was achieved in hydrocarbon exploration during recent years.

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