湖北兴山寒武系覃家庙群底部三叶虫化石的地层学意义

A TRILOBITE FAUNA FROM THE CAMBRIAN QINJIAMIAO GROUP IN XINGSHAN,HUBEI PROVINCE AND ITS STRATIGRAPHICAL SIGNIFICANCE

三峡地区覃家庙群以一套缺乏化石的薄层白云岩沉积为特征。新近在湖北兴山古洞口剖面覃家庙群底部发现Kaotaia gedongensis Yuan & Zhao,Kunmingaspis yunnanensis Chang,Chittidilla sp.等三叶虫。依据三叶虫生物地层学对比结果,结合研究剖面与覃家庙群标准剖面和参考剖面岩石地层学对比,认为三峡地区覃家庙群为跨传统下、中寒武统的地层单元。

The Qinjiamiao Group in the Yangtze Gorge area is mainly composed of thin-bedded dolostones. Because this group yields scarce fossils, its depositional age was poorly constrained. New trilobites （e. g. , Kaotaia gedongensis Yuan ＆ Zhao,Kunrningaspis yunnanensis Chang,Chittidilla sp. ） collected from the basal Qinjiamiao Group at Gudongkou, Xingshan County of Hubei Province provide reliable evidence for a Cambrian age. Based on lithostratigraphical and biostratigraphical correlations among different sections in the Yangtze Block, we concluded that the basal Qinjiamiao Group in the Yangtze Gorge area was deposited in the traditional Early Cambrian and Middle Cambrian.