Formation mechanism of high quality marine source rocks—Coupled control mechanism of geological environment and organism evolution

Abstract

High quality marine source rock (HQMSR) is the key prerequisite for medium to large hydrocarbon accumulations. However, the forming mechanism remains unclear. On the basis of the investigation for the geodynamic setting of the Middle-Upper Yangtze during the Early Cambrian in different spatial scales and the analysis of trace elements, the main controlling factors of the development of high quality marine source rock are discussed, with specific consideration of the burial rate of the organic matter. The formation of high quality marine source rocks is suggested to be the result of a coordinated development and the interaction between geological environments and organism evolution during the major geological transition periods. We perceived that the burial rate of organic matter was influenced by the primary productivity and its burial conditions. The abundance of autogenetic molybdenum gained directly by the chemical speciation analysis of rocks could be used as a proxy for the burial organic matter. The burial rate of autogenetic molybdenum and the sedimentary organics in modern marine environments could be used to estimate the sedimentary organics in ancient environments effectively.