Tertiary paleogeography of the East and South China Seas

Abstract

Abstract Tertiary reservoirs and source rocks throughout the East and South China Seas vary from continental in nature to marine. Understanding the Tertiary paleogeography of the East and South China Seas facilitates predictions about expected reservoir, source and seal packages throughout the region, as well as providing some insight into possible timing of charge and migration. The paleogeographic reconstructions of the East and South China Seas utilize a global scale general model, which incorporates global paleogeographic plate reconstructions and Cretaceous through Cenozoic General Circulation climate models. With the global model as a base, the detailed reconstructions incorporate the distribution of the lithofacies observed in all available wells and the integration of published stratigraphic and paleogeographic information. Depositional and structural models and global eustatic sea-level curves provide constraint between data points. Paleogeographic maps are constructed for the Late Cretaceous-Early Paleocene, the Late Paleocene to Early Eocene, the Middle Eocene, the Late Eocene, the Oligocene-Early Miocene, and the Late Miocene. The paleogeographic reconstructions represent a geologically consistent, albeit not necessarily unique, solution to the Tertiary development of the East and South China Seas. Some time between the Early and Late Cretaceous, extensional faulting, most likely the result of transverse movements along several northwest-southeast trending strike-slip faults, resulted in the development of two belts of depressions within the East and South China Seas. The inner belt is comprised of the Wenchang, Enping, Xijiang, Huizhou, Lufeng, Hangjiang, Liaoshui, and Jiaojiang Depressions, whereas the outer belt is comprised of the Kaiping, Baiyun, Chaosan, South Taiwan, Jilong and Xihu Depressions. Eocene and younger movements along the Red River Fault system, associated with Himalayan extrusion, impacted the development of the Beibuwan, Yinggehai and Qiongdongnan Basins. The distribution of continental and marine facies was strongly influenced by the differential tectonic development of these basins.