Print this pageThe Features of Structures and Evolution of Wanan Basin in South China Sea
KAIYI, FAN, and QIAN GUANGHUA
Wanan basin is a Cenozoic strike-slip basin overprint on attenuated continental crust. The basement is mainly composed of Mesozoic granite and metamorphic rocks. The basin has experienced two major phases of extension rift in early Tertiary and post rift in late Tertiary. Sediments, with a thickness of 6100m, were deposited in rift stage with the environments changes from fluvial and lacustrine-transitional - half enclosed shallow marine. then the episode of marine transgression in large scale occurred in post rift stage, and deposited of neritic and bathyal sequence with a thickness of 4000m. These two phases formed the basical petroliferous geological conditions of the basin.
The extensive basement faulting activities resulted in the tectonic framework of 3 uplifts and 4 depressions which control the development of various traps. Succession traps related to basement are dominated within the basin and have a good assemblage with various oil and gas systems which indicates a prospective new venture.