Abstract: The sedimentary setting and environmental mark study shows that there exist multi-zone coal measures with vertical plant root fossils as well as mud-cracked structure. The seismic facies study indicates that the developed structures include prograding configuration, rhythm-inverted distributary mouth bar on braided delta front and turbidite in bathyal lake mud, belonging to typical braided delta system. Based on the study of lithofacies, log facies and seismic facies, Aershan and Tengger formations can be divided into nine microfacies. In terms of the oil abundance, from high to low, these microfacies are successively beach sand, distributary mouth bar, sand sheet, turbidite, submerged branch channel, distal bar and underwater splay sand.

Key words: Erlian basin, sedimentary facies, seismic facies, log facies, delta