内蒙古乌拉山群麻粒岩相岩石中变质矿物的标型特征  

TYPOMORPHIC CHARACTERS OF METAMORPHIC MINERALS IN THE GRANULITE FACIES ROCKS OF THE ARCHEAN WULASHAN GROUP IN INNER MONGOLIA

作　　者：甘盛飞[1] 钱祥麟[2] 

机构地区：[1]沈阳黄金学院地质学系,沈阳110015 [2]北京大学地质系,北京100871

出　　处：《矿物学报》1992年第4期334-343,共10页Acta Mineralogica Sinica

摘　　要：晚太古宙乌拉山群高级变质岩系分布于内蒙古大青山地区,包括各种麻粒岩和片麻岩,构成了东西走向的大青山太古宙麻粒岩带。本文对这套岩石中的斜方辉石、单斜辉石、石榴子石、角闪石、黑云母的物性和成分标型特征进行了系统分析。结果表明,这些矿物均为麻粒岩相条件下变质而成,并反映在发生麻粒岩相变质时,大青山南麓乌拉山群岩石的变质温度和压力均高于北边的岩石。High-grade metamorphic rocks of the Late-Archean Wulashan Group distributed in the Mt. Daqingshan area of Inner Mongolia constitute the Mt. Daqingshan Archean granulite belt at the northern margin of North China Craton. Typomorphic characters of pyroxenes, garnets, hornblen des and biotites in the rocks of the Wulashan Group show that these minerals are of granulite-facies metamorphic origins. Oithopyroxene and clinopyroxene were formed during granulite-facies metamorphism at high temperature. High content CaO in clinopyroxene and low Al_2O_3 in both clinopyroxene and orthopyroxene are noticed, as compared with the pyroxenes in other Archean regions in the North China Craton. With metamorphic temperature decreasing, the contents of MnO and FeO increase while MgO and Mg/(Mg+Fe) decrease in zoned garnet, and FeO increases and Mg, TiO_2/MnO, Mg/Fe decrease in biotite. The content of Al^(Ⅵ) decreases in hornblende with metamorphic pressure decreasing. Changes in chemical compositions of all these minerals demonstrate that the metamorphic temperature and pressure of the rocks in the southern part of Mt. Daqingshan are higher than those in the northern part, suggesting that the rocks of the Wulashan Group in the southern part of Mt. Daqingshan were located at deeper levels of the lower crust than those in the northern part during the period of Archean granulitefacies metamorphism.

关 键 词：麻粒岩 岩相 岩石 变质矿物 标型 

分 类 号：P588.346[天文地球—岩石学]