Abstract: Based on the integrated analysis of seismic,drilling and outcrop data,this paper studied the deposition and sequence stratigraphy characteristics of Shiniulan & Xiaoheba formations in southeastern Sichuan-northern Guizhou pro-vinces.The following results were obtained.The Shiniulan Fm and its underlying Longmaxi Formation compose a separate third-order sequence,and the Shiniulan Formation is part of a high-stand system tract.There are two sub-eustatic sea le-vel cycles in the Shiniulan Formation,so this formation can be further divided into an upper and a lower fourth-order sequence.There are one to two development phases of platform margin reef & bank facies in the high-stand system tract of each fourth-order sequence,but the best platform reef & bank facies lies in the upper one.The bioherms developed during the deposition of the Shiniulan Formation are generally small and in scattered or beaded distribution due to the non-exis-tence of obvious slope break between platform margin and slope as well as the dilution of terrigenous inputs.In the study area,the dolomitization of the Shiniulan Fm is very weak as a whole.It is assumed that the salinity was low in this stage mainly due to factors.The first is the input of fresh water from the central Guizhou Uplift in the south and Xuefeng Uplift in the east.The second is the low amplitude of uplift of platform margin reef & bank.The sedimentary environment of the Xiaoheba Formation in Nanchuan area should be a shallow water constructive delta with low river energy,non-well deve-loped provenance and predominant suspension transport.

Key words: sedimentary facies, sequence stratigraphy, Shiniulan Formation, Xiaoheba Formation, Silurian, Central Guizhou Uplift, Xuefeng Uplift