Depositional systems in the Palaeogene Hetaoyuan Formation in southern Biyang depression

The present paper gives a detailed description of the depositional systems in the Palaeogene Hetaoyuan Formation in southern Biyang depression on the basis of geological, cores, well logs and seismic data. Two depositional systems have been distinguished, including the fan delta and lacustrine depositional systems. The fan delta depositional system consists of fan-delta plain, fan-delta front and pro-fan delta subfacies. The lacustrine depositional system is built up of the shallow lake, bathyal lake and abyssal lake subfacies. The sediment detritus are derived mainly from the Pingshi and Yangqiao regions. Finally the sedimentary models are constructed, and the favourable areas are delimited for future petroleum exploration.