贵州紫云扁平村石炭纪珊瑚礁剖面微相分析与沉积相

Sedimentary Environment and Microfacies Analysis of a Carboniferous Coral Reef in the Bianping Village of Ziyun County,Guizhou

扁平村生物礁产于马平组Triticites带内,Fomitchevella骨架构成生物礁主体。扁平村的这种以珊瑚为主要造礁生物的石炭纪生物礁在全球也是不多见的。本文以实测剖面微相分析为主要手段,观察、分析珊瑚礁的生长、沉积环境,对该珊瑚礁的剖面进行详细的微相分析。我们总结了6个微相;划分出5个沉积相:在剖面上由下至上,相1较浅的受保护的台地相,相2搅动水中的浅滩相,相3较深的开阔台地相,相4浪基面以上斜坡相,珊瑚礁在这个相上发育起来,就是相5珊瑚礁相,再向上为相3,相1;进一步总结出了与圆丘礁缓坡类型相似的局部相模式;并分析了珊瑚礁生长、沉积环境。总体上剖面沉积环境为潮下开阔台地环境。

The Bianping organic reef occurs in the Triticites belt of Maping Formation, Fomitchevella framework builds up its principal part. The type of the Bianping organic reef , a Carboniferous one with corals as dominating reefbuilder, is uncommon in the world. In this paper the Bianping coral reef＇s growth and sedimentary environments are observed and analyzed by the way of detailed section microfacies analysis. We define and interprete 6 microfacies types. 5 facies are identified in the section as follows： From the bottom up, facies 1 ： a little protected environment on shallower open platform ; facies 2 ： shoal in agitated warm water; facies 3 ： deeper open platform ; facies 4 ： slope above wave base, Fomitchevella growing on facies 4 subsequently, that is facies 5 - coral reef; then facies 3, and facies 1. In addition, a sedimentary model similar to type Ⅱ of shelf margin profile： knoll reef ramps is summarized. Fomitchevella reef＇s growth and sedimentary environments are interpreted and analyzed. As a whole, the sedimentary environment of the section should be a subtidal open platform.