EVOLUTION OF THE PERMIAN SEDIMENTARY BASINS IN EASTERN CHINA

The study area in the present study occupies five provinces in eastern China, i. e. Fujian, Zhejiang, Jiangxi and parts of Jiangsu and Anhui. The Permian sedimentary basins in eastern China are interpreted as the inherited depressed basins on the continental crust, characterized by less mobility and relative stability (including sedimentation, tectonism and volcanism). Therefore, they have the features of the cratonic basins. These Permian sedimentary basins may be classified into two groups:depressed basins and faulted basins. Their basement comprises the Presinian or Early Palaeozoic metamorphic rocks. Seven sedimentary associations have been distinguished for the sedimentary sequence. They are, from base upwards, lower coal-bearing elastic rock association; lower carbonate rock association; lower siliceous rock association or clastic rock or carbonate rock association; clastic rock association or coal-bearing clastic rock association; upper coal-bearing clastic rock association; upper carbonate rock association, and upper siliceous rock association or carbonate rock or clastic rock association. There is a wide range of the Permian sedimentary environments. The sedimentary facies are complex but are regularly aligned and controlled by the tectonic framework and old land. The evolution of the sedimentary basins may involve four stages. Stage 1 is characterized by transgressive overlap and basin expansion; Stage 2 by basin differentiation and severe basement faulting; Stage 3 by regression and basin shrinkage, and Stage 4 by transgression and basin redifferentiation.