Keywords: 
• lacustrine fan /
• growth fan /
• paleogeomorphology /
• channel /
• Shahejie Formation /
• Western sag

Abstract: There are gravity flow sediment in the third section, Shahejie Formation, Eocene in Shuangtaizi Structure Belt, Liaohe depression. Middle fan and outer fan are the main types of sedimentary facies. Growth fault and palaeogeomorphology co-controlled the deposition, and their distribution characteristics are depicted. Then, sedimentary facies controlling factors are studied. A sedimentary model that channel controlled distribution of sand, slope gradient controlled shape, and provenance controlled supplement of sediment  is built up. Braided channel is controlled by growth fault and paleogeomorphology. Through the study of sedimentary facies, several results are concluded: in Shuangnan, as the slope of paleo-geomorphology is gentle, the transport distance of the braided channel sediments is long, the sinuosity is great, depositional differentiation is apparent, and the sediments characteristic is thin bed interbedding of sandstone and mudstone. However, in Shuangtaizi, as the slope of paleo-geomorphology is sharp, the transport distance of the braided channel sediments is short, the sinuosity is low, sedimentary differentiation is weak, and the sediments characteristic is interbedding of thick bed sandstone and thin bed mudstone. The differences of sedimentary mechanism between Shuangtaizi and Shuangnan make differences of the sedimentary facies distribution and sand body interbedding architectures in these two areas. Shuangtaizi has better sedimentary facies than Shuangnan, which is important to the reservoir quality.