Abstract: The deposition of Shanxi Formation in Jiaxian- Zizhou area, Ordos basin belongs to a lacustrine deltaic depositional system which evolved from the transitional facies of Carboniferous Taiyuan Formation. The deltaic deposition can be divided into delta plain and delta front subfacies. Microfacies of the delta plain consist of channel, levee, coal-bearing swamp and depression between channels, and crevasse splay. Microfacies of the delta front include subaqueous distributary channel, channel mouth bar, distal bar, subaqueous levee, frontal sheet sand, and interdistributary bay. By studying these microfacies, the evolutional process of the depositional environment and the approximate extension of the sand bodies are envisaged. The results of this work can be used for better exploration targeting and estimation of hydrocarbon reserves in the area.

Key words: sedimentary facies, delta, sand body, Shanxi formation, Ordos basin