摘要
通过对研究区内的五通组几条代表性剖面的岩性、岩相及化石特征和地层区域展布等研究并进行区域对比,结合近年来的区调及科研成果,提出巢湖地区五通组观山段至擂鼓台段中部的下黏土层的时代属于晚泥盆世晚期斯图期,而擂鼓台段中部的上黏土层与上部为早石炭世早期杜内期,泥盆系-石炭系界线位于上、下黏土层之间石英砂岩中(狮子口剖面31层的顶面);擂鼓台段下部与中部之间有一沉积间断面,有铁质风化壳,局部见褐铁矿化砾岩层,这一间断面是泥盆纪末期大海退在本区的反映;巢湖地区五通组并非陆相沉积,而是一套海相的滨岸相沉积,海水主要来自北东方向,与过去的陆相沉积和海侵来自南西方向的论点有所不同。
Based on recent geological mapping and careful lithostratigraphic, lithofacies and biostratigraphic study of several sections in the Chaohu region,we propose several new interpretations of the Devonian-Carboniferous Wutong Formation. Our data suggest that the Guanshan Member and the lower clay unit of the middle Leigutai Member of the Wutong Formation in the Chaohu represent deposits of the Upper Devonian Strunian stage. The upper clay of the middle Leigutai Member and the upper Leigutai Member of the Wutong Formation are probably of Early Carboniferous Tournaician age. The Devonian-Carboniferous boundary is located in a quartz sand stone between the two clay units of the middle Leigutai Member （i. e. , the top of bed 31 in section 1）. We also recognized a discontinuity surface,with iron weathering crust and ferruginous conglomerates,between the lower and middle Leigutai Member. We interpret this discontinuity surface as representing a regression event near the Devonian Carboniferous boundary. Furthermore,we argue the Wutong Formation in the Chaohu region does not represent terrestrial deposition;instead,it is interpreted as littoral facies marine deposits ,with oceanic transgression from the northeast to the southwest, This interpretation is in sharp contrast to traditional view that the Wutong Formation in the Chaohu region represents terrestrial sedimentation and the open marine was located in the southwest.
出处
《地层学杂志》
CSCD
北大核心
2006年第2期157-170,共14页
Journal of Stratigraphy
基金
国家自然科学基金(No.40472117)
安徽省省级地质勘查专项费项目资助(No.2003-29)。
