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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.
Hubei Xingshan Xiakou section is located in the middle Triassic in the Yangtze River carbonate gentle slope deeper waters, is China’s marine Permian - Triassic typical of one of the profiles.According to the section of the Triassic Daye formation strata Based on the vertical distributions of these species and the regional data, the early Triassic bivalves in this area are divided into four biogenic units, which are: (1) Claraiastachei-C.griesbachi zone; (2) Claraia concentrica (3) Eumorphotis multiformis-E.in-aequicostata band; (4) Posidoniacircularis-P.cf.wengensis band. In order to investigate the relationship between biome appearance and environmental evolution, (1) Claraiaconcentrica-C.aurita community; (2) Eumorphotisinaequicostata-E.multiformis community; (3) Posidoniacircularis community. Early Early Triassic double The succession of shell communities indicates that the early Triassic Early Dienerian sea water once became shallow, and then the water body gradually deepened with the expansion of the transgression.The marine environment turbulence after the end of Permian extinction may be early Triassic marine ecosystem recovery process extended important reason.