Yang, Yongtai¹ 
(1) University of Toronto, Toronto, ON

ABSTRACT: Tectonic and Sedimentary Evolution History and Petroleum Systems in the Ordos Basin, Central China

The Ordos Basin is located in central China, and presently, it is a petroliferous basin with the greatest increment of proven hydrocarbon reserves on the Chinese continent. The basin is developed on the ancient Huabei Platform composed of Archaeozoic and Lower-Middle Proterozoic crystalline basement. The sedimentary cover consists of carbonates and clastics with a maximum thickness of 10 km. These sediments were developed in five stages: the Middle-Late Proterozoic aulacogen stage, the Early Paleozoic cratonic basin stage, Late Paleozoic cratonic basin stage transiting from marine to continent, Mesozoic foreland-cratonic basin stage and Cenozoic faulted basin stage. Two petroleum systems are identified in this basin, the Lower Ordovician/Upper Paleozoic-Lower Ordovician/Upper Paleozoic and Upper Triassic-Upper Triassic/Lower Jurassic. The Paleozoic petroleum system, situated in the central and northern part of the basin, is characterized by Lower Ordovician marine carbonates and Upper Carboniferous and Lower Permian coal measures as source rocks, and its reservoirs are dominated by karst-modified dolomites of Lower Ordovician and deltaic sandstones of Upper Carboniferous and Lower Permian. The Mesozoic petroleum system covers the central and southern part of the basin, with Upper Triassic lacustrine mudstones as source rocks and Upper Triassic deltaic and the Lower Jurassic fluvial sandstones as reservoirs. The formation and conservation of the oil and gas fields in both petroleum systems are attributed to the stable tectonic evolution of the basin. Traps are mainly stratigraphic and lithologic, controlled by paleo-valleys, deltaic sand bodies and weathered crust.

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.