湘黔地区震旦纪菌藻硅质岩特征及形成机理探讨

湘黔地区震旦纪菌藻硅质岩化学成分纯净,硅质矿物含量95%以上,几乎都为泥晶—微晶石英,石英结晶度平均为6.35。岩石具菌藻生物结构,以纹层状构造为主。其中丰富的菌藻生物化石,按形态可划分为三种类型。岩石属原生沉积成因,二氧化硅的聚沉一方面通过菌藻有机体的硅化作用,另一方面是菌藻生物化学作用引起微环境变化而导致二氧化硅的聚沉。

THE CHARACTERISTICS AND DISCUSSION OF FORMING MECHANISM OF THE SINIAN ALGAL AND BACTERIA CHERTS IN HUNAN AND GUIZHOU PROVINCES

Chemical composition of the Sinian algal and bacteria cherts in Hunan and Guizhou provinces are very pure,and the content of siliceous mineral exceeds 95 percent,and almost of them are composed of micritic quartz. The average value of quartz crystallinity index is 6.35. The cherts are mainly characterized by algal and bacteria texture and laminar structure. Abundant algal and bacteria microbiota fossils are divided into three types in shape. Silicon precipitation occured during primary sedimentation. One way of silicon accumulation and sedimentation is the silication of algal and bacteria organisms. Another is that the microenvironment changes caused by algal and bacteria biogeochemical processes results in silicon accumulation and sedimentation.