Analysis based on outcrop and drilling data indicates that source rocks can be formed in different tectonic settings. Transgressive process is benefit for source rocks development in various tectonic environments. Source rock development environment is increasingly limited from basin stretching to stable subsidence and finally to returning stage. The extensive transgressive overlap in stretching process is most favorable for the deposition of source rock in a large area. Source rocks are mainly distributed in the platform edge shelf and internal depression in stable subsidence stage. The closed environments such as intra-platform depression and regions behind high energy facies are favorable for source rock development in the returning stage. Sedimentary sequence and tectonic evolution show that the Cambrian-Ordovician source rocks in Tarim Basin experienced a whole process from basin stretching to returning stage

i. e. basin stretching in the Early Cambrian

stable subsidence in the Middle Cambrian to Middle Ordovician

and tectonic return in the Late Ordovician to Silurian. So that

3 types prototype basins were formed. Stretching process in the Early Cambrian was the best period for source rock development. The northern depression

shelf in the southern basin edge and basin facies were the best zones. The basin showed difference in east and west during the Early and Middle Ordovician

and platform edge and limited basin developed in Manjiaer depression Aman transitional belt

being favorable for the development of source rocks. In the Late Ordovician

besides the high energy belt on the platform edge

Awati Depression and Aman transitional belt were intra-platform depressions

where limestone was deposited and was favorble for source rock development. Therefore

the major source rocks at different positions have different characteristics.