THE LATE PALEOZOIC SEDIMENTARY FRAMEWORK AND THE OIL/GAS POTENTIAL OF THE YANGTZE BLOCK AND ITS BORDERING AREAS

The S.China Continental Block (i.e equivalent to the Yangtze together with the southern China Cakdonian Foldbelt) is an ancient continent in the Paleo-Tethyan Ocean,whose bordering areas had been intracontinental faultdowns during the early evolution arystage,which transformed into a devergent and passive continental margin (the oceanictrough of the S.Qinling belt along the N.margin should be attributed to an intracontinental aulocogen) in the late stage.At the sametime,the enlargement of the Xiang-Guisea basin by transgression reached the middle and lower Yangtze areas during early Hercynian period,followed by a more extensive transgression during the Permian-Triassic time due to the Yunnan movement initiated at the end of the Carboniferous,Therefore,thecontinental plate was surrounded by island chain system on the bordering areas while theepicontinental sea occurred within the plate dominated by the differentiation of the platform and the basin regime,in a pattern similar to that of the present South China Sea andthe Caribbean Sea basins.Since the two sea basins are rich in oil/gas resources,in turn,itis suggested that large oil/gas fields should be discovered in the S.China,especially in Permian-Triassic systems dominated by epicontinental sea basin environment.