南黄海盆地东北凹侏罗纪地层的发现及其分布特征

根据南黄海盆地北部坳陷东北凹新的钻井和地震资料,本文详细研究了该凹陷新钻遇地层的地震反射特征及典型岩 性剖面,对该套地层内具有代表性的深度层位采集沉积碎屑样品,利用孢粉组合特征综合判定了该套地层的沉积年代,结 合相邻盆地侏罗纪地层发育情况,认为该套地层为中-晚侏罗世。从岩性及孢粉组合上该井主钻遇地层可划分为上下两个 组合,上组合以裸子植物花粉特别是克拉梭粉占绝对优势,下组合具有较高含量的桫椤孢和克拉梭粉,以此推断南黄海盆 地东北凹是以中-晚侏罗世为主的沉积凹陷。根据井震标定信息,结合凹陷内二维地震测网综合地震追踪对比结果,凹陷 内侏罗系呈现西北厚东南薄的格局,北部千里岩隆起带为盆地的重要物源区。

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.