Abstract: The Silurian Tata’airtage Formation in the Tarim River area,Xinjiang may be divided,on the basis of cores,well logs and seismic data,into two lithologic members belonging to the offshore(barrier) depositional systems.The lower member is composed of the high tide flat(mud flat) and middle tide flat(mixed flat),while the upper member consists of the low tide flat(sand flat).The offshore(barrier) in the Tarim River area is the Tabei(Xayar) palaeouplift,and the open sea is the South Tianshan Ocean.The provenances include Kuluketage in the northeastern part and Altun Mountains in the southern part.