Abstract: Comparative Study of the Mature Basin of the Bohai Bay and New Frontier Basins of the Mongolian Plateau, China

WU, CHANGLIN, and DON TURNE

The subduction of the Pacific plate under the Eurasian continent created two groups of rift basins in eastern China. The Hailaer and Erlian basins are in one group that was developed by regional extension far behind the active plate margin in the Mesozoic. Both were filled with Jurassic-Cretaceous lacustrine-fluvial sediments over 3.5-4.0 km thick. The Bohai basin, in the group of Cenozoic rift basins, was created by doming and rifting caused by subduction near the active plate margin. It has over 6.0 km of lacustrine-fluvial sedimentary fill. The Bohai and Hailaer-Erlian basins share many structural and sedimentary characteristics that are typical for intraplate rift systems. Both are characterized by rapid subsidence, numerous half-grabens, active faulting, widespread volcanic intrusion, and tripartite facies through rifting (fluvial-lacustrine-fluvial).

The Bohai basin has proved to be a giant petroleum province. This study reveals that the Bohai is a good analog for the Hailaer and Erlian basins in terms of hydrocarbon habitat. Buried-hills, fault blocks, and draped anticlines are the major structural plays. Black lacustrine shales with an average TOC of 1.8-3.4% are the major source rocks and are thermally mature. Delta-front, subaqueous fan, deep lake turbidite, channel, and fluvial sandstones with porosity of 17%- 25% are the principal reservoir rocks. Commercial hydrocarbon flows have been discovered in the lacustrine succession of the Aershan Structural Zone in the Erlian basin, and Beierhu-Huhehu Drepressions in the Hailaer basin. High hydrocarbon potential probably exists in the unexplored depressions of the two basins.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria