Fluvial deposition and evolution of Yan 9 oilbearing interval of the Middle Jurassic Yanan Formation in Huachi area， Ordos Basin
1 Institute of Sedimentary Geology，Chengdu University of Technology， Chengdu 610059，Sichuan
2 College of Resources Science & Technology， Beijing Normal University， Beijing 100875
3 Institute of Sedimentary Basin， China University of Geosciences（Beijing）， Beijing 100083
Based on a new stratigraphic division and large quantities of drilling，outcrop and core data，the authors have studied in detail the depositional system， lithofacies palaeogeographic characteristics and evolution of the Yan 9 oilbearing interval of the Yanan Formation in Huachi area， Ordos Basin. The results indicate that the Yan 9 oilbearing interval is dominated by fluvial deposits and was inherited and developed from the Yan 10 oilbearing interval. During the deposition of Yan 9， mainly braided fluvial， braided meandering fluvial and anastomosed fluvial facies were developed. Braided fluvial facies was developed in the Y39 interval and Y29 interval inherited the fuvial deposits of Y39， and formed the braided meandering fluvial facies. After the two former stages of filling process， anastomosed fluvial deposits were developed in the Y19 interval in the peneplain environment. Two fluvial depositional models were developed in the Yan 9 oilbearing interval in Huachi area，namely as， braided fluvialbraided meandering fluvial and anastomosed fluvial depositional models.
. Fluvial deposition and evolution of Yan 9 oilbearing interval of the Middle Jurassic Yanan Formation in Huachi area， Ordos Basin[J]. JOPC, 2009, 11(3): 275-183.
