巢县二叠系栖霞组臭灰岩段异地成因碳酸盐岩

下扬子地区二叠系栖霞组臭灰岩段广泛发育。以巢县为例 ,研究表明组成臭灰岩段的石灰砾岩并非正常沉积。剖面特征 ,岩石学、沉积学和地球化学特征的分析结果 ,显示了石灰砾岩的砾石来源于浅海碳酸盐台地 ,它们作为碳酸盐岩碎屑流的产物 ,沿着台地边缘的斜坡 ,被搬运到半深海—斜坡处再沉积。环绕于砾石周围的胶结物和砾岩层之间的薄层硅质粒泥灰岩 ,主要是由等深流沉积物组成。因此 ,臭灰岩段碳酸盐岩主要是异地成因 ,沉积环境属于碳酸盐台地周缘水体较深的斜坡。

ALLOCHTHONOUS CARBONATE ROCKS IN THE SWINE LIMESTONE MEMBER OF THE PERMIAN CHIHSIA FORMATION OF CHAOXIAN, ANHUI

Swine Limestone Member of the Permian Chihsia (Qixia) Formation, is developed widely in the Lower Yangtze Region. The limestone conglomerates of the Swine Limestone Member are not normal deposits. The analysis of the characteristics of the profile, petrology, sedimentology and geochemistry show that the gravel came from the shallow water carbonate platform and was transported to the slope or bathyal zone as carbonate debris flow along the slope of margin of carbonate platform. The cements surrounding gravels and thin bedded silicic packestones between limestone conglomerates are comprised mainly of sediments of contour currents. Thus, carbonate rocks of Swine Limestone Member of the Chihsia Formation are largely allochthonous and were deposited on the deeper water slope of the margin of carbonate platform.