皖赣鄣公山地区新元古代地壳组成及造山过程

皖赣相邻的鄣公山地区位处江南造山带北缘,区内广布一套厚度巨大、低绿片岩相变质的以泥砂质细碎屑岩为主含少量火山物质的复理石建造体,大量高精度同位素测年数据显示,其形成于821～840Ma间的新元古代早期,以景德镇-鄣源-伏川区域断裂带为界,南部为形成于大陆边缘拉张构造环境下的溪口岩群;北部的双桥山群火山-陆缘细碎屑岩系是与岛弧有关盆地中的沉积物。北东—南西向展布于鄣公山北坡的蚀变枕状-块状基性火山熔岩、辉长岩、辉绿岩等基性岩类呈构造碎块或碎片产出于溪口岩群火山-陆缘细碎屑岩组成的复理石基质中,通过对其产出地质特征及岩石地球化学特征等的分析,认为其形成于低速扩张的陆缘小洋盆扩张脊环境,具初始洋壳基性岩特征,属皖南伏川蛇绿岩西延组成部分。呈夹层产出于双桥山群地层中的大量玻屑晶屑凝灰岩及少量变安山岩、变流纹岩等具相似的岩石地球化学特征,属中钾钙碱性岩石系列,形成于大陆边缘火山弧构造环境。综合区内沉积事件、岩浆事件和构造事件等,提出皖赣相邻区新元古代经历了古扬子板块东南缘裂开-陆缘小洋盆有限俯冲-弧陆碰撞造山-造山期后陆壳裂陷沉积的构造演化过程。

Neoproterozoic Crustal Composition and Orogenic Process of the Zhanggongshan Area, Anhui-Jiangxi

Zhanggongshan area of Anhui-Jiangxi border,located in the northern margin of the Jiangnan orogen (South Yangtze River),contains very thick low greenschist-facies metamorphic flysch rocks dominated by argillo calcareous fine-grained clastic rocks with minor volcanic materials. A mass of high precise isotopic dating shows that it may form in early Neoproterozoic between 821~840 Ma,bordered by the Jingdezhen-Zhangyuan-Fuchuan regional faulting belt. The Xikou Group in the southern part resulted from extension ...