TECTONIC FRAMEWORKS OF THE BOHAI GULF AND COASTAL, BASINS

The Bobai Gulf and its coastal basin is an important oil and gas province of China that covers an area of 200,000 sq. km.
It is a polycylic superimposed basin. Its history of development can be subdivided into four stages:(i) Late Proterozoic parageosydine stage (Sinian); (ii) Early palaeozoic cratonic stage (Lower Cambrian-Middle Ordovician):(iii) Late palaeozoic intracratonic coal bearing sequences stage (Middle Carboniferous-Permian); (iv) Mesozoic and Cenozoic taphrogenic rifting and subsidence stages.
During the Paieogene rifting stage, three NNE trough systems and three nearly EW trough systems were initialed as the results of regional extensional stresses. Central rift valleys, low angle gravity faults and a series of asymmetrical half-grabens were developed surrounding the "Bohai Mantle Plume". The riftitip troughs were egtended ard widened gradually.