Abstract

The Dongting Basin is a composite fluvio-lacustrine basin formed by rifting and regional subsidence. Rifting first occurred in the Early Cretaceous, at which time three isolated half graben were formed. In the Late Cretaceous a large inland drainage basin was formed and the three graben were linked through regional subsidence, caused by sediment loading, into a larger basinal area. Tertiary tectonism, related to the Himalayan collision, reactivated faulting in areas overlying the Early Cretaceous basins.

Up to 4.5 km of Cretaceous and Tertiary non-marine sediments are preserved. Source rocks are found in saline lake facies within the rift basins. Reservoirs are found in fluvial and lacustrine delta sands which are strongly controlled by provenance.

Reprocessed seismic data illustrate three east dipping half graben which contain hanging wall anticline and rotated fault block traps. Buried hill type traps may be present on the footwalls of intra-basinal faults.