安徽巢湖地区中二叠统栖霞组的遗迹化石特征及其沉积环境

在安徽巢湖177高地、无为白牡山等地中二叠统栖霞组顶部灰岩段和臭灰岩段发现大量遗迹化石Zoophycos cf.caudagalli。这些遗迹化石以系统觅食迹为主,指示水动力及波浪作用较弱、贫氧的深水沉积环境。在栖霞组的砾状灰岩中,发现部分Zoophycos穿插于灰岩砾石和基质之中,这揭示栖霞组石灰砾岩中的砾石并非成岩作用成因,而是碎屑流沉积形成,属于异地成因碳酸盐岩。综合巢湖地区栖霞组的地层和岩石地球化学特征以及Zoophycos的生活习性和分布特征,发现表明巢湖地区中二叠统栖霞组臭灰岩段和顶部灰岩段属于贫氧的碳酸盐台缘斜坡沉积。

TRACE FOSSILS AND THEIR SEDIMENTARY ENVIRONMENT OF THE MIDDLE PERMIAN CHIHSIA FORMATION IN CHAOHU,ANHUI PROVINCE

Trace fossils are reported from the Middle Permian Chihsia Formation at 177 Highland and Baimushan in Chaohu,Anhui Province.These trace fossils occur,in the bituminous limestone and the upper limestone members of the Chihsia Formation.They are identified as Zoophycos cf.caudagalli Vanuxem,1842.Zoophycos,is a fodinichnion and typically occurs in deeper-water dysoxic sedimentary environment.In the Chihsia Formation,some Zoophycos fossils are found in the matrix of conglomerates,suggesting that the gravels represent debris flows and they are allochthonous.On the basis of integrated analysis of stratigraphic,geochemical,paleoenvironmental,and paleoichnological datas,the bituminous limestone and upper limestone members of the Chihsia Formation in Chaohu were interpreted to have been deposited in dysoxic slope settings on the margin of a carbonate platform.