The Formation and Distribution of the Marine Hydrocarbon Source Rock in the Tarim Basin,NW China

There are significant differences in type and distribution between marine source rock and continental source rock.According to the lithology,the Cambrian-Ordovician source rock in the Tarim basin is divided into two types:the carbonate source rock and the mud source rock.The two sets of source rocks are developed mainly in three sets of formations,Lower-Middle Cambrian carbonate source rock and mud source rock,Lower-Middle Ordovician mud source rock and Upper Ordovician lime mud source rock.The stratigraphic and areal distributions of the source rocks are controlled by the altitude and the sedimentary facies respectively.The mud source rock is developed in slope-semi deep sea environment.The source rock developed in the slope sedimentary environment is related with the anoxic environment and the one developed in semi deep sea has a close relationship with the up-flowing sea water.The carbonate source rock is developed mainly in platform slope of highstand systems tract and it is usually intimately associated with the salt rock.The Lower-Middle Cambrian carbonate source rock is developed mainly in the Bachu,Tazhong,Tangguzibasi and Yingmaili areas.The Lower-Middle Cambrian mud source rock is mainly developed in the areas east of the line of Kunan 1-Tadong 1.The Lower-Middle Ordovician mud source rock is developed mainly in the east slope of the Manjiaer depression.The carbonate source rock of Early Ordovician is developed mainly in the platform slope of highstand systems tract,such as the south margin of Tabei, the north slope of Tazhong,the Bachu area and Keping area.