Abstract: Detailed studies of a number of core sections, well logs and seismic data of the Biyang depression reveal that the depression had a special construction style and forming mechanism. In southern and eastern basin, where the main controlling faulting is apparent, steep slope growth break sequence dominates. The northern side of the basin belongs to a typical gentle slope sequence, resembling the grouth fault sequence model of the Gulf of Mexico. Through analyzing the particular structural background, which controlled predominantly the sequence system tracts, the pattern of strata sequence and deposition of the Biyang depression are established. The authors believe that the whole terrigenous sequence stratigraphy of the Biyang depression could be divided into four parts: lowstand systems tract, transgressive systems tract, highstand systems tract , and regressive systems tract. Three types of delta sandstones, fandelta , near source delta and the far source delta, have been recognized in the primary oil bearing layers of the Early Tertiary Hetaoyang Formation. Their capibility to host petroleum is also discussed.

Key words: Biyang depression, sequence stratigraphy, system tract, depositional system, model of sequence stratigraphy