Abstract: Fuxian area is located in southeastern part of Ordos basin where a set of delta-lacustrine terrigenous clastic sediments with coal is found in Yanchang formation of its Triassic system. During the process of sedimentation and evolution of Yanchang formation, Chang10-Chang7 members were characterized by lacustrine expansion, whereas Chang6-Changl members by lacustrine shrinkage. Since the character and evolution of the lacustrine water body could not only prov ide the important information of the basin's depositional evolution, but also it has the great influence on the sedimentation of the lacustrine-delta sand bodies. Based on the analyses of the microelecments obtained from the mudstones of Y anchang formation in Fuxian area, this paper makes study and prediction of the property of water body, palaeoclimate and sedimentation in period of Yanchang, which could be as a good supporting evidence for study of origin and distribution of the sand bodies in Yanchang formation.

Key words: Ordos basin, microelement, quantity, feature, env ironment