| There are 4 suites of Paleozoic marine source rocks, including the Lower Cambrian,the Upper Ordovician-Lower Silirian, the Lower and the Upper Permian ones, in the studied area of South China. These source rocks can be divided into 7 favorable depo-biofacies: namely deep-water argillaceous shelf facies, deep-hot-water shelf facies, deep-water carbonate shelf facies, deep-water silicophosphatic platform-seg facies, bay lagoon facies, offshore lake-basin swamp facies and prodelta facies. The 4 suites of depo-biofacies diagrams of regional marine source
rocks indicate that all of these facies are connected to some extent with oceans. These facies of source rocks repre sented to diversify from Early Cambrian to Late Permian periods. Influenced by the Douyun and Dongwu Movements, the distribution area of favorable facies zones varied from broadness to narrowness in two cycles. The development of marine source rocks in South China has been controlled by five factors, such as plate movements, intraplate active ties,the three big palaeohighs, the four transform periods and depo-biofacies. The formation pattern of marine
source rocks in South China consists of the deep-water shelf and benthonic algal mats characterized by the up growth of benthonic algae, the oxidation of depositional surface but reduction of burial settings. This pattern differs in these characters from the other three formation patterns that have already occurred. In the studied area, the Qingling Ocean in the north, the Huanan Ocean in the south(Pz1)and the Babu Ocean (Pz2) intruded into the Yangtse Craton to form “bay systems”at different times,which are cradles for the development of marine source rocks and significant targets to explore marine oils and gases in Southern China. |
