Characteristics of Sedimentary Facies and Sequence Boundary in Upper Cretaceous Qingshankou-Yaojia Formation of Northern Songliao Basin
ZHUO Hong-chun1 LIN Chun-ming1 LI Yan-li1 FENG Zhi-qiang2 ZHANG Shun2 ZHAO Bo2 (1.Department of Earth Sciences, State Key Laboratory of Ore Genesis,Nanjing University, Nanjing 210093; 2.Exploration and Development Research Institute of Daqing Oil Field Company Ltd., Daqing, Heilongjiang 163712)
Qingshankou and Yaojia Formation developed delta and lacustrine facies along the long axis of the basin during the period of depression. Qingshankou Formation consists of littoral lake, shallow lake and semi-deep lake facies. Yaojia Formation consists of delta plain, delta front and prodelta facies. Base on analyses of drilling cores, from the top of Quantou Formation to the top of Yaojia Formation can be divided into 6 sequences, and corresponding to 7 sequence boundaries. One of the sequence boundaries is supersequence boundary. Sequence boundary is characterized by paleosol, erosional surface, calcareous nodules, and truncation. Generally, oolitic limestone, bioclastic limestone, worm boring and pyrite develop above the sequence boundary.
【CateGory Index】： P539.2