麻粒岩概论

    AN OUTLINE OF GRANULITE

    • 摘要: 麻粒岩可以划分为两个亚类(长英质和铁镁质),并依据复合命名原则再划分种属。强烈的定向压力对麻粒岩的形成起着重大的作用,它不仅影响到麻粒岩的结构和构造,而且还导致石英发生塑性形变,长石及辉石发生出溶,甚至形成高压麻粒岩矿物共生组合,使石榴石形成压力影及使它的A°/N比值发生变化。

       

      Abstract: Granulite is a high-grade regional metamorphic rock of multiple origins formed under solid-phase conditions. It contains such characteristic minerals as pyrope, sillimanite, exsolved perthite and exsolved anti-perthite in addition to hypersthene of regional origin. Granulite may be divided into two subclasses (feldspathic and mafic) and further divided into species. Strong oriented pressure plays an important role in the formation of granulite, which not only influences the textures and struc- tures of granulite but also results in plastic deformation of quartz, exsolu- tion of feldspar and pyroxene and even formation of high-pressure mineral paragenesis of granulite so that pressure shadows of garnet are formed and its A~0/N ratio changes. In order to identify granulite correctly, it is necessary to erase the effect of migmatization and distinguish between biotite granulitite and metamagmatic rocks.

       

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