钱塘拗陷早二叠世层序地层及其底界

The sequence stratigraphy and boundary during earliest permian in qiantang region

本文根据层序地层学的观点，分析了早二叠世钱塘拗陷与扬子区沉积环境的不同和沉积物的差异；同时在原来石炭系的上部找到了Ｍｉｓｅｌｌｉｎａｃｌａｕｄｉａｅ（Ｄｅｐｒａｔ）科化石，因此提出了新的早二叠世地层的底界。

Through recent research,the original stratigraphical division was not only inappropriate in palaeontology,but also in lithostratigraphy.During earliest permian,Yangzi region belongs to be erasionsl plain,where there was not deposited while Qiantang region being foreslope,where there were limestone and detrital sediment.When Yangzi region began to deposit with detrital sediments of Liangshan formation,Qiantang region with carbonatite deposits.The different depositional environment results in the respected straum. Therefore,it is difficult to apply lithostratigraphlical method.At the same time,the author.studied the Misellina claudiae(Deprat)fossils collected from the upper part of the Chuanshan formation in Hangzhou,Zhejiang, and considered that they belong to the upper carboniferous.It is generally recognized by chiness and foreign gelolgists that fossils is in early Permian.According to sequence stratigraphy principle and thd fossils, the original stratigraphical boundary should be revisioned.The author proposed in this paper thd new boundary between carboniferous and permian in Qiantang region, between stratum No.1 and No.2.The dark grey thin-medium bedded limestone and carbonaceous limestione with Misellena claudiae zone below the elastic rock member and above thd Cirvanella zone of Chuanshan formation should be regarded as the lower part of Permian system.