康定—泸定地区出露的新元古代变质侵入岩位于扬子板块西缘北段。通过详细的野外地质特征、岩相学、矿物学及岩石地球化学等方面的研究,确定岩石组合为辉长岩、石英闪长岩、英云闪长岩、花岗闪长岩、二长花岗岩和正长花岗岩,其中以中酸性岩为主,具有钙碱性演化特征;长石成分主要为钠长石—更长石—中长石,含水矿物角闪石、黑云母广泛存在;主量元素显示钙碱性分异趋势;微量元素呈现典型的岛弧环境地球化学特征;稀土配分模式呈右倾型;在构造环境判别图中,该变质侵入岩样品均投影于火山弧区域。综合以上特征表明康定—泸定地区变质侵入岩在新元古代处于与俯冲有关的岩浆弧环境。
The Kangding-Luding metamorphosed intrusions are distributed in northwestern margin of the Yang-tze block.On the basis of the field geological characteristics,petrography,mineralogy and geochemistry,we demonstrate that rock types include gabbro,quartzdiorite,tonalite,granodiorite,adamellite,syenogranite,in which intermediate acid rocks are majority;The rocks are dominantly moderate-K calc-alkaline series;Components of plagioclase include albite,oligoclase and andesine,hornblende and biotite exist extensively;The intrusions have calc-alkaline differential trend in major element compositions.Their trace elements show typical geochemical characteristics of island arc setting;REE patterns are of slightly right-inclined type;On the diagram of tectonic settings,they are mainly located at the range of VAG.Above mentioned characteristics suggest that the Kangding-Luding metamorphosed intrusions were formed at the magmatic arc setting.