城巴断块区明月剖面震旦系陡山沱组层序地层学研究

Study on the stratigraphic sequence of Sinian Doushantuo Formation in Mingyue Section,Chengba Fault Block

陡山沱组为气候变暧后的第一套沉积组合,其内化石稀少,同位素年龄数据有限,地理分布不平衡,极易造成认识上的混乱。尝试从层序地层学的角度来探讨明月剖面震旦系陡山沱组层序地层特征,继而为研究陡山沱组黑色岩系成矿性打下基础。通过野外观测和室内综合研究,并结合区域地层对比,将大巴山地区明月剖面震旦系陡山沱组地层层序划分为4个二级层序(sequence)、9个三级层序(cycle),对层序Ⅲ又进一步划分为9个四级副层序,最后得出明月剖面震旦系陡山沱组地层层序与Hoffman等1998年提出的"雪球地球"假说所描述的基本类似,为下一步找矿指明了思路。

The Doushantuo Formation in Mingyue Section of Chengba Fault Block is the first set of sedimentary assemblage after cli- mate warming. Therefore, it has rare fossils, limited isotopic age data, unbalanced geographic distribution, which could easily cause confusion. The study tried to explore the characteristics of stratigraphic sequence of Doushantuo Formation, which was supposed to lay the foundation for the study of the mineralization of its black lithology. Based on field inspection, indoor study and regional stratigraphic correlation, the paper classified the sequence of Sinian Doushantuo Formation into 4 second-order sequences, 9 third-order cycles and Sequence Ⅲ into 9 fourth-order para-sequences. At last, it is pointed out that the sequence of Doushantuo Formation is similar to that of the Snowball Earth Hypothesis of Hoffman et al. （1998） , and indicated the direction of future prospecting.