内蒙古卓资孔兹岩系中石榴石成分环带及其在温压估算中的应用

内蒙卓资出一了大面积太古宙矽线石榴黑云二长片麻岩，其中石榴石的Ｍｇ、〈Ｆｅ〉、Ｍｇ／（Ｍｇ＋Ｆｅ）等呈明显的环带特点。研究表明，石榴石既存在生长环带，也具有扩散环带。其成分环带与石榴石生长过程和变质条件有关。不同成分环带的热力学计算，可以确定变质作用过程中不同阶段的温压条件。

THE COMPOSITIONAL ZONING OF GARNET OF PRECAMBRIAN KHONDALITE SERIES AND ITS APPLICATION TO TEMPERATURE-PRESSURE ESTIMATION IN ZHUOZI, INNER MONGOLIA

Mg,of garnet display an evident composition zoning feature inprecambrian Khondalite series in Zhuozi area. According to the genetic characteristics,they are divided into tvvo types of compositional zoning,the growth zoning and diffusivezoning. The growth zoning reflectsd the process of crystallization and growth of garnet,while the diffusive zoning responds to diffusion between garnet and biotite at the post-peak cooling stage. Granitic magmatism deeply influences the compositional zoning ofgarnet,which not only causes garnets being assenbled together,but also produces newgrowth zoning surrounding the rim of assemblage, With the help of garnet- biotitegeothermometer-barometer,as wellas different genetic types of compositional zoning ingarnet the peak-stage and post-peak cooling stage metamorphic temperature-pressureconditions could be determined.