湖北宜昌樟村坪地区陡山沱组地层划分与对比

Stratigraphic Division and Correlation of Ediacaran Doushantuo Formation in Zhangcunping Area,Yichang,Hubei Province

华南峡东地区(黄陵隆起南缘)的陡山沱组是国际上埃迪卡拉纪地层和生物与环境事件的研究热点之一,但近在咫尺的黄陵北缘陡山沱组地层研究相对较少,已有的研究不足以反映黄陵北缘陡山沱组地层的特征,甚至与黄陵南缘地区未能建立起明确的对比关系.选取了黄陵北缘樟村坪及其周边地区的4个完整的陡山沱组剖面进行研究,以完整连续的钻孔剖面为依据,配合露头剖面的宏观沉积现象,对埃迪卡拉系陡山沱组进行详细的划分和对比.将樟村坪地区陡山沱组岩石地层划分出4个岩性段,并在层序地层学上划分出两个半三级层序,层序界面分别位于陡山沱组底界、陡山沱组第二段第二亚段顶界和陡山沱组第三段与第四段分界处.通过与黄陵隆起南缘陡山沱组各段岩性比较分析,建立了南、北缘地层对比联系,从而为黄陵北缘磷矿区的地层学研究奠定了基础.

The Ediacaran Doushantuo Formation in Yangtze Gorges area is one of the most intensively investigated units for Ediacaran biological and environmental study in the world.However,the Doushantuo Formation was less investigated in the northern Huangling area than the southern one.The correlation of Doushantuo Formation between the two areas is still unclear.Four complete sections of the Doushantuo Formation,including two drill cores and two outcrop sections,are documented in this paper.The Doushantuo Formation in the northern Huangling area is subdivided into four members.Three sequence boundaries are recognized in the Doushantuo Formation,separately at the base of MemberⅠ,the top of the second part of MemberⅡand the boundary between MemberⅢ and MemberⅣ.According to the lithostratigraphic and sequence stratigraphic studies,the Doushantuo Formation between the northern and southern Huangling areas can be well correlated.This study providesafirm base for the statigraphic study of the phosphate strata.