安徽南陵—铜陵地区茅口期碳酸盐孤立台地沉积特征分析

Sedimentary Feature of An Isolated Carbonate Platform of Maokouian in Nanling-Tongling ,Anhui

本文分析了安徽南陵-铜陵地区茅口期的沉积特征。描述和讨论的主要岩石类型有亮晶生物屑灰岩、泥晶海百合丘灰岩、含有机质藻粒泥晶灰岩、放射虫硅质岩及含钙质生物硅质岩。结合古生物和其它各种相标志,共划分出五个微相,即深水盆地、盆地边缘、碳酸盐缓坡、生屑浅滩和泻湖-潮坪相。研究区茅口期的沉积模式是一个被深水盆地包围的碳酸盐孤立台地。其地貌特征可与现代大巴哈马滩类比,所不同的是它发育了布满海百合灰泥丘的缓坡带。该孤立台地的沉积演化表现为向上变浅的海退序列。

This paper deals with scdlimentary feature of Maokouian in Nanling-Tongling areas of Anhui . Main types of rock are described and discussed: sparry bioclastic limestone、 micritic cncrinite、 organic alge micrite、 radiolarian chert and calcareous bioclastic chert. By connecting with palaeotological and other facics indexes, five different microfacies are established: deep basin, basin margin , carbonate ramp, bioclastic shoal and lagoon-tidal flat. A depsitional modal of Maokouian in the study area is an isolated Platform surrounded by deep basin , and its mophology can be compared with the Bahamas bank, but it is different with the Bahamas Bank in its ramp full of mud mounds composed crinoid lime. Depositional evolution of this isolated platform shows a shallowing-upwards regressive sequence