华北地台早前寒武纪变质岩系中角闪石的化学组分特征

本区角闪石包括所有的四个大类,共计27种。闪石的Ti,Al,Na+K等组分与变质温度、压力密切相关,这些组分可作为估测变质温度、压力的标志.而闪石的Fe,Ca等组分则主要受寄主岩石的控制。随变质程度减弱,闪石种类变化顺序为:浅闪石、镁绿钙闪石钙镁闪石镁角闪石阳起石。镁角闪石可作为划分高、中、低级变质作用的标志.钙镁闪石可作为区分麻粒岩和高级角闪岩相的指示矿物。

CHEMICAL FEATURES AND GEOLOGICAL; SIGNIFICANCE OF AMPHIBOLE IN EARLY PRECAMBRIAN METAMORPHIC ROCKS OF NORTH CHINA PLATFORM

This paper discusses 82 amphiboles oceurreing in Early Prccambrian mctamorphic rocks from 6 areas of North China platform. The amphibole in the areas includes all four groups,27 species in all.Ti,Al and Na+K components of the amphibole arc closely related to the temperature and pressure of metamorphism; therefore, these components can be regarded as the marks in estimating T and P. But Fe and Ca components of the amphibole arc mainly controlled by their host rocks. With mctamorphic degree decreased, the amphibole species changs sequence is as follows: cdcnite,hastingsitc-tschcrmakite-magnesiohornblcnde-actinolitc.Thc magncsiohornblende is a mark in distinguishing the high, the midand the low-degree of metamorphism. The tschcrmakite could be regarded as a indicator mineral for dividing the granulite and high-amphibolitc facics.