Discovery of the Jurassic Strata in the North-East Sag of South Yellow Sea

Based on the newly drilled well S1 and seismic data in north-east sag, northern depression, South Yellow Sea, this paper analyzed the seismic reflective features and lithology of the well S1 in detail. In order to constrain the age of the target strata,paleontological and Sporopollen study is carried out for core samples. Based on the result of these studies and the regional correlation,it is proposed that the target strata are Middle-Late Jurassic in age. From lithologic association and Sporoplllen assemblages, the drilled strata can be divided into two parts, the upper one is dominated by Gymosperm pollen especially Classopollis and the lower one has high contents of Cyathea spores and Classopollis. According to the well-seismic calibration, the 2D seismic interpretation is tracked throughout the sag, it is showed that the Jurassic strata in this sag get increasingly thicker from southeast to northwest in sedimentary framework.We suggested that the Qianliyan uplifted zone in the north side of the sag may be the main provenance for the Jurassic strata.