TIME-SPATIAL DEVELOPING FEATURES OF CO-EXISTED INHERITED AND NEOGENIC STRUCTURES AND THEIR GUIDANCE TO MARINE ORIGIN OIL-GAS EXPLORATION IN THE YANGTZE CRATON

The study on time-spatial developing features of co-existed inherited and neogenic structures is an important step for the basin-orogeny coupling from a direction of petroliferous basin study to a guidance of oil-gas exploration.The exploration of marine origin oil-gas pool in China has taken a very tortuous road,and now it is in urgent need of new theoretical guiding.Taking the northern part of Upper Yangtze area(the Sichuan Basin) as an example,the paper described the orientation of structural line and its mechanism(coupled evolution with the neighbouring orogenic occurring) in the Precambrian,Caledonian,Hercynian-Indosinian and Yanshanian tectonic stages.A key knowledges for recent good progress of marine oil-gas exploration in the easetrn Sichuan Basin was lithologic-structural compound pool created by the Yanshanian neogenic structure(NE-orientation) acrossing the syn-marine sedimentary neogenic structure(NW-striking),which were named the 2nd and 3rd generation of neogenic structures respectively.In the western Sichuan Basin,the 3rd generation of neogenic structure was NEE-striking.To compare with eastern Sichuan,the paper analysed the orientation of structural line of each tectonic stage in the southern part of Upper Yangtze area(Guizhou) and Middle Yangtze area(Hubei) respectively.An obvious distinction in Guizhou might be that evolution of the epicontinental sea basin was coupled with the Babu-Phu Ngu ocean to the south(instead of the Qinling-Dabie ocean to thenorth of the Yangtze craton).In addition,Guizhou area was influenced by the plume tectonics in Late Permian-Early Triassic.The unique basemental structures(the N-S Huangling continental nucleus and the NE-striking Paleo-Tan-Lu fault zone) in Middle Yangtze area constrained the regional formation and deformation for a long time.Based on what mentioned above,the beneficial districts for marine oil-gas exploration in Guizhou and Hubei areas was discussed,which thought that the North Guizhou Basin(to the north of Guiyang-Anshun in west Guizhou) might be a hopeful area,although the orientations of Late Paleozoic and Mesozoic neogenic structures varied from the Sichuan Basin.