湖北兴山峡口早三叠世双壳类生物地层及古群落分析  

Early Triassic Bivalve Biostratigraphy and Paleocommunities at Xiakou Section in Xingshan,Hubei Province

作　　者：李慧[1] 童金南[1] 任江波[1] 张杰[1] 

机构地区：[1]中国地质大学生物地质与环境地质教育部重点实验室,湖北武汉430074

出　　处：《地球科学（中国地质大学学报）》2009年第5期733-742,共10页Earth Science-Journal of China University of Geosciences

基　　金：国家自然科学基金项目(Nos.40621002;40830212);科技部基础研究项目(No.2006FY120300-11)

摘　　要：湖北兴山峡口剖面位于早三叠世中扬子碳酸盐缓坡较深水区域,是我国海相二叠系-三叠系典型剖面之一.根据该剖面下三叠统大冶组地层中双壳类的垂直分布,结合区域资料,将该地区早三叠世早期双壳类划分为4个生物地层单位,自下而上依次为:(1)Claraiastachei-C.griesbachi带;(2)Claraia concentrica-C.hubeiensis带;(3)Eumorphotis multiformis-E.in-aequicostata带;(4)Posidoniacircularis-P.cf.wengensis带.为了探讨生物群面貌与环境演变之间的关系,根据双壳类的产出特征及其赋存岩石的沉积特征,建立了3个化石群落:(1)Claraiaconcentrica-C.aurita群落;(2)Eumorphotisinaequicostata-E.multiformis群落;(3)Posidoniacircularis群落.早三叠世早期双壳类群落演替,反映了该地区早三叠世早Dienerian期海水曾一度变浅,之后随着海侵的扩大,水体逐渐加深.二叠纪末生物大灭绝后海洋环境动荡,可能是早三叠世海洋生态系复苏过程延长的重要原因.According to the vertical distribution of bivalves in the Lower Triassic Daye Formation at the Xiakou Section in Xingshan, Hubei Province, four bivalve biostratigraphic zones are recognized in ascending order： Claraia stachei-C, griesbachi Zone, Claraia concentrica-C, hubeiensis Zone, Eumorphotis multi formis-E. inaequicostata Zone, and Posidonia. circularisP. cf. wengensis Zone. In addition, based on the occurrence and ecology of bivalves and their associations as well as the sedi mentary facies, three communities are retrieved, i.e. Claraia concentrica-C, aurita Community, Eumorphotis inaequicostata- E. multiforrnis Community, and Posidonia circularis Community. The evolutionary succession of the communities indicates that the area was shallow in the early Dienerian and became deeper since then with the transgression in the Early Triassic. The turbulence of the Early Triassic environment prolongated the restoration of marine ecosystem after the end-Permian mass extinction.

关 键 词：早三叠世 双壳类 生物地层 群落 湖北兴山峡口. 

分 类 号：P534[天文地球—古生物学与地层学] Q911[天文地球—地质学]