A VIEW ON TECTONICS OF PALEOZOIC BASINS OF THE YANGTZE REGION AND ITS IMPLICATION OF HYDROCARBONS

Regional investigation shows that the evolution of the Paleozoic basins on the Yangtze Craton experienced a primary extensional rifting in which smaller collage blocks with a great mobility and inhomogeneity were assembled during the end of middle Proterozoic and then the Paleozoic basins began to be disintegrated. The aulacogen in the north was of oceanicc rust and was later obliterated by the collision at the end of Silurian. Meanwhile rift-margin made up in the south was accreted with exotic collage blocks elavated. As a regional convergence, several cratonic depressions associated with occasional extensional rifting developed with the seawater invasion of Paleo-Tethys mainly from southwest in late Paleazoic. Some blocks separated from the southern craton during Carboniferous-Permian-late Triassic periods came into collision again.Consequently, the framework of Paleozoic basins were reformed as a result of intraplate deformation with crustal-stacking or delamination during Meso-Cenozoic, rifting to the collision of Paleo-Neo-Tethys and the effect of the Pacific Plate. As mentioned aboved, it is suggested that Paleozoic hydrocarbons were mainly generated from the present mountain belt, where the content of organic carbon is much more abundant than that carbonate platform. The subsidence in early Paleozoic perhaps played an important role in generation and migration of hydrocarbons before Caledonian. The napping may be favourable to the conservation of the generated hydrocarbons and the perspecting area could included some favourable belts such as the Foothills of Longmen and Daba mountains, and nor-thern fringe of the Xiafung-Jiannan Hill are worthy to be explored furthermore.