THE PROTOTYPES OF LATE PALEOZOIC PETROLIFEROUS BASINS IN LOWER SECTION AREA OF YANGTZE RIVER

The characters of deposition and subsidence in lower section area of Yangtze River are discussed in this paper.The authors of this paper point out that the pre-Cambrian basement in the area is composed of Paleo-core, Qiantang Arc Rising Belt and Cathaysia. Firstly, Dongan-Jinning movement cratonized the Yangtze Para-platform and the Caledonian movement ceased the developing stage of trough-platform(graben), and then transformed into the developing stage of cratonic syneclise depressions and basins. In this paper, the characteristics of Late Paleozoic protobasins are described in detail.The structure zones are classified and divided into three developing stages, depending on the structure evolution history,i.e. faultdown, depression and transformation stages. Indosinian-Early Yenshan movement is a major event which reworked the Late Paleozoic basins and resulted the intraplate deformation of severe foldings and nappings, trending from southeast to northwest in the Paleozoic sequences. The deformation pattern mainly is basement decoupling and the foredeep depressions formed at fore-nappings. Such a movement reworked Late Paleozoic intra-plate depression,and superposed and preserved the depression as well.All of these mentioned undoubtedly would provide favourable conditions for the Paleozoic oil/gas generation and accumulation and in addition, the petroli-ferous prospects in Meso-Cenozoic foredeep depression also can not be ignored.