The characteristic of sequence stratigraphy and depositional systems of the Palaeogene Kuqa depression

The strata in the Palaeogene Kuqa depression has been classified into 5 the 3rd order sequences,24 the 4th order sequences based on the integrated study on outcrops and well logs.Several kinds of depositional systems have been identified,such as alluvial fan deposits,fluvial and delta deposits,incised valley filling,evaporite salt lake deposit,lagoon or sea gull deposit,flooding basin deposit,lacustrine deposit,gravity or turbidity flow deposit,and so on.According to the depositional composition and its development feature in foreland basin,the sequence can be classified into 6 kinds.The development and distribution of every kind of sequence in foreland basin also have been summarized in this paper.