Abstract:

Cambrian-Ordovician is the main horizon for the development of hydrocarbon source rocks in Tarim Basin. The muddy hydrocarbon source rocks are the dominant type for the Manjiaer Depression and its surrounding in this period. According to the data from outcrop sections and wells along with the analysis of basin tectonic evolution, it can be seen that the environments in which the muddy hydrocarbon source rocks were deposited include shelf with upper welling activity, normal shelf, restricted bay, deep ocean floor and inundated carbonate platform, and the tectonic settings for these environments belong to passive continental margin, deep rift basin and stable craton, respectively. The concentrations of organic matter for the muddy hydrocarbon source rocks deposited in different sedimentary tectonic settings are of quite difference. There is the highest TOC concentration in the muddy source rocks deposited in the shelf with upper welling activity, then those in the restricted bay and normal shelf. The TOC concentration in the muddy source rocks deposited in the deep ocean floor is much lower than those in the shelf. There is the lowest TOC concentration in the muddy source rocks deposited in the stable inundated carbonate platform. These facts illustrate the control of sedimentary-tectonic settings on the development of marine muddy hydrocarbon source rocks.

Key words: muddy hydrocarbon source rock, sedimentary-tectonic setting, Cambrian Ordovician, Tarim Basin