据牙形石论鄂西茅口组顶部古岩溶不整合面形成时代

摘要

The conodonts illustrated in this paper were collected from paleokarst unconformity at the top of the Permian Maokou Formation,western Hubei.The conodonts are products of redeposition,as shown by color,luster and worn-out character of samples.Based on the evolutionary characteristics,geological time limits and modes of occurrence of connodonts,the paleokarst unconformity is considered to be of Late Wordian—Early Capitanian in Permian.(i.e., upper part of M.aserrata zone—M.postserrta zone).%鄂西二叠纪茅口组顶部古岩溶不整合面粘土层中产丰富的牙形石，计有3属3种2未定种，标本色泽和被磨损特征等显示它们均为再沉积产物。通过对上述牙形石属种的演化特征、地质时限及产出层位的研究，认为该古岩溶不整合的形成时代为二叠纪Wordian晚期—Capitanian早期（M. aserrata 带上部—M. postserrata带）