康定群的地质特征及其在扬子地台基底演化中的意义

THE CHARACTERISTICS OF THE KANGDING GROUP AND ITS IMPLICATION FOR THE EVOLUTION OF THE YANGTZE PLATFORM BASEMENT

摘要: 本文首先对康定群的地层划分及时代作了详细的阐述,并根据该群原岩的岩石类型及其建造、微量元素、稀土元素等特征,确认康定群属于早前寒武纪花岗绿岩带性质。同时,还对该绿岩带存在的三个问题及其演化模式,进行深入的分析与探讨。

Abstract: The basement of the Yangtze platform consists of two structural layers. The old one is the Kangding Group （crystalline basement） and the young one the Huili Group （folded basement）. The Kangding Group is composed of three parts: the tholeiitic series in the lower, the calc-alkali series in the middle and the sedimentary series in the upper, totalling over 10000 m in thickness. They have all undergone regional metamorphism and migmatization to different degrees. Two terranes can be recognized in the crystalline basement, i.e. the gneiss-granulite terrane and the granite-greenstone terrane. Based on the distribution, protolith formation sequence and geochemistry, the Kangding Group is considered as the early Precambrian greenstone belt.