扬子地块北缘武当山岩群与耀岭河岩群不整合接触关系的地质意义

鄂西北南化塘地区中元古界武当山岩群由三个岩段组成，其原岩分别以火山角砾岩、岩屑凝灰岩及晶屑凝灰岩为主。它们的空间展布与上覆上元古界耀岭河岩群高角度相交，三岩段所显示出早期褶皱也只限于武当山岩群内部，与上覆岩群的构造轮廓极不谐调，耀岭河岩群没有经历过这一期变形。因此，武当山岩群与耀岭河岩群之间最初存在着明显的角度不整合接触。该区域不整合面的厘定和早晋宁运动的确认将改变以往关于扬子地块北缘构造层的划分及构造演化历史的认识，对研究秦岭造山带的造山过程具有重要意义。

THE CONTRACT RELATION OF THE WUDANGSHANG GROUP AND THE YAOLINGHE GROUPIN THE NORTH MARGIN OF YANGZI MASSIFAND ITS SIGNIFICANCE

Based on the 1:50000 regional geological mapping,the metaacid volcanic rock series of the Middle Proterozoic Wudangshan group can be divided into three Parts:the protolithes of which are respectively volcanic breccia,rock fragment tuff and Crystallino- elastic tuff facies.The group is as high angh angle to the overlying upper proterozoic Yaolinghe group.The structureal outlines of the groups are discordance and the early folds reserved inthe Wudangshan group are only limited in itself. Therefore it is determed that there exists a high angle unconformity between the,groups. By the isotopic age stata from the groups, the unconformity was formed about 1 000Ma. which is the early Jonning movement in the north margin of Yangzi massif.The discovery is very importantfor the division about tectonic layer of the area, for the researching on the tectonic evolution of the north marginof Yangzi massif and the orogenic process of the Qinling belt.