湖北宜昌奥陶系庙坡组疑源类

ORDOVICIAN ACRITARCHS FROM THE MIAOPO FORMATION OF YICHANG,HUBEI

湖北宜昌地区庙坡组是达瑞威尔阶/桑比阶界线附近的地层,该段地层产出分异度较高,丰度适中的疑源类组合。该组合包括16属,28种,其中7个未定命名种,可与国内、外同期疑源类组合进行对比。庙坡组疑源类组合既产出晚奥陶世特征分子,也产出阿伦尼格期(弗洛阶上部—达瑞威尔阶底部)的特征分子,显示出一定的过渡特色。组合以Baltisphaeridium(17%—52%),Leiosphaeridia(6%—78%)占优势;反映了其沉积环境为离岸较远的外陆棚环境。

A moderately abundant and diverse acritarch assemblage was recovered from the Miaopo Formation at 4 sections in Yichang area, Hubei, South China. The acritarch assemblage consists of 28 species assigned to 17 genera. Compared with those of a similar age in other places, the acritarch assemblages of the Miaopo Formation in Yichang show not only typical acritarch species of the Upper Ordovician, but those of the Arenig. The acritarch assemblage is dominated by Baltisphaeridium and Leiosphaeridia, followed by Ordovicidium and Polygonium. The acritarch assemblage, as also suggested by brachiopod fauna, may imply the outer-shelf deep-water environment of the Miaopo Formation.