POOL-FORMING ZONALITY OF BIOGASES IN THE CENOZOIC BASINS OF DIAN-QIAN-GUI AREA

Under the "land-to-land" collision and matching structural action of the Indian Plate to the Euro-Asian Plate, a series of small intermountain strike-slip and pull-apart basins of the Eocene-Oligocene, the Miocene and the third stage of the Pliocene were formed along large strike-slip fault zones in Guangxi, West Yunnan and East Yunnan-South Guizhou areas during the Himalayan Ⅰ,Ⅱ and Ⅲ episodes. Three stages of the basins developed in three areas had different structural and sedimentary evolutionary characteristics, and resulted in different pool-forming conditions of biogases for the basins of each area. Biogas pools mainly distributed in the Eocene-Oligocene and the Pliocene basins in West Guangxi and East Yunnan-South Guizhou areas. In each basin, controlled by fall velocity, sedimentary facies zones, source rock depth, fault developing density, trap types and stratigraphic denuded degree, biogas pool-forming conditions were clearly different in each zone. Biogas pools distributed in the deep sags and adjacent zones of each basin.