滇西昌宁地区西盟岩群地球化学特征及原岩恢复

Geochemical Characteristics and Protolith of the Ximeng Group in the Changning Area, West Yunnan

研究区西盟岩群分为a,b,c三段,主要的岩石类型包括片岩类、片麻岩类、变粒岩类、长英质糜棱岩类、大理岩类和花岗岩类。通过具代表性的29件样品进行主量元素、稀土元素和地球化学数据恢复原岩表明,黑云片岩类和石英片岩类的原岩总体应为副变质岩,可能由粉砂质粘土岩或泥岩变质而成;角闪黑云片岩的原岩可能是中基性火山岩;片麻岩类的原岩多数为长石砂岩,少数为中酸性岩浆岩;长英质糜棱岩类可能为中酸性的岩浆岩变质后再经韧性剪切变形改造而成。

The Ximeng Group may be divided into a, b and c Members which are composed of schist, gneiss, granofels, felsic mylonite, marble and granitoid. Major element and REE analyses for 29 samples show that protolith of biotite schist and quartz schist as parametamorphic rock should be silty calyrock or mudrock, protolith of amphibole-biotite schist should be intermediate-basic volcanic rock, protolith of gneiss--arkose and a small amount of intermediate-acid magmatic rock and protolith of felsic mylonite--intermediate-acid magmatic rock and shear-deformed.