东海西湖凹陷下第三系层序地层学分析
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摘要
运用威尔（Ｐ．Ｒ．Ｖａｉｌ）等人提出的层序地层学原理，对东海西湖凹陷下第三系层序地层学进行分析研究。笔者认为西湖凹陷层序的发育虽受到构造运动的影响，但层序的形成、发育和结束主要受控于海平面升降的变化。海平面变化的频繁周期性，决定了生物面貌，体系域发育和沉积相的基本特征。本文侧重分析了始新世平湖组（Ⅱ＿２－Ⅱ＿６）发育的低位体系域、海进体系域和高位体系域，并利用地震、钻井、测井等资料论述了不同体系域中的各种沉积相的沉积、电测曲线及地震相特征。同时，对渐新世花港组（Ⅲ＿１－Ⅲ＿２）的层序也作了分析。文章指出：平湖组海进体系域形成的泻湖、潮间－潮下带的暗色泥岩是成烃的主要源岩；潮道砂和高位体系域形成的三角洲砂体，花港组低位体系域的三角洲、河道砂是本区主要的储集岩。因此，西湖凹陷具备了良好的油气生成环境，在构造、储集条件匹配的圈闭内就可形成油气田。
Under the guidance of the new concept of sequence stratigraphy put forward by P.R.Vail et.al.,etc,we make a study of sequence stratigraphy on Eogene System in Xihu Sag and come to the conclusion that,although the characteristics of sequences in Xihu Sag were influenced by tectonic movernent,the forming,developing and ending of se-quences were controlled by the changes of sea level which also have influences on theprincipal characteristics of biology,system tracts and facies.The paper lays emphasis on the analysis of system tracts(LST,TST,HST)formedin Pinghu Formation(Eocene,Ⅱ_2-Ⅱ_6),the characteristics of facies,logs and seismics invarious system tracts based on the data concerning seismic,drill,logs etc,and several se-quences in Huagang Formation(Oligocene,Ⅲ_1-Ⅲ_2)。The authors suggest that the principal source rocks in Pinghu Formtion are lagoon-al,intertidal-subtidal dark mudstones formed in TST,and that principal reservoir rocksare tidal channel sands(formed in TST),delta sands(formed in HST)in Pinghu Forma-tion and delta , channel sands formed in LST in Huagang Formation. So,Xihu Sag hasgood conditions for the forming of petroleum province under the suitable tectonism.
Under the guidance of the new concept of sequence stratigraphy put forward by P.R.Vail et.al.,etc,we make a study of sequence stratigraphy on Eogene System in Xihu Sag and come to the conclusion that,although the characteristics of sequences in Xihu Sag were influenced by tectonic movernent,the forming,developing and ending of se-quences were controlled by the changes of sea level which also have influences on theprincipal characteristics of biology,system tracts and facies.The paper lays emphasis on the analysis of system tracts(LST,TST,HST)formedin Pinghu Formation(Eocene,Ⅱ_2-Ⅱ_6),the characteristics of facies,logs and seismics invarious system tracts based on the data concerning seismic,drill,logs etc,and several se-quences in Huagang Formation(Oligocene,Ⅲ_1-Ⅲ_2)。The authors suggest that the principal source rocks in Pinghu Formtion are lagoon-al,intertidal-subtidal dark mudstones formed in TST,and that principal reservoir rocksare tidal channel sands(formed in TST),delta sands(formed in HST)in Pinghu Forma-tion and delta , channel sands formed in LST in Huagang Formation. So,Xihu Sag hasgood conditions for the forming of petroleum province under the suitable tectonism.
引文
1JohnB．Sangree，PeterR．Vail著，张宏远等译．应用层序地层学．山东东营：石油大学出版社，1991．2杨兆宇．东海新生代沉积盆地的类型和成盆期．海洋地质与第四纪地质，1992，12（2）：1－10．3地质矿产部海洋地质综合研究大队、中国地质科学院地质研究所．东海陆架新生代古生物群．北京：地质出版社，1989．4俞印生．东海陆架盆地新生代地层层序及沉积特征．中国海区及邻区地质地球物理特征．北京：科学出版社，1992，302－307．5孙永传．碎屑岩沉积相和沉积环境．北京：地质出版社，1986．
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