摘要
冀东太平寨地区太古宙麻粒岩相变质杂岩中,含有岩浆成因和变质成因的两类斜方辉石,后者又可分为早、晚两期。在地质产状研究的基础上,据岩相学、矿物化学成分和温度、压力条件,阐明了斜方辉石的成因。研究结果为该区划分地质事件和探索早期地壳演化历史提供了重要的依据。
Orthopyroxene group occurs in charnockitic gneisses and in their enclaves (meta-ultramafic and mafic rocks, granulites, BIF, etc), as well as in metabasic dykes in Taipingzhai area from Eastern Hebei Province. Origin of Orthopyroxene group is very complex in this area. Some of which, blas-tohypersthenes, were formed from magmatism, then reformed during meta-morphism. The others, metahypersthenes, were formed during metamorphi-sm. The earlier coarser meta-hypersthene(0.3-1mm) and the later finer one (0.01-0.1mm)were formed in different periods of granulite facies respectively.The compositions of orthopyroxee .are not contelled distinctly by the compositions of prototith in rocks. The major compositions of hypersthene, except Al2O3, SiO2, PeO, MgO, CaO decrease respectively with the increase of deformation.The calculated temperature of the earlier hypersthene is 880 ×60℃ and the later is 820 *60? by two pyroxenes geothermeter, which suggests these pypersthenes have been subjected to pyroxene granulite subfacies metamor-phism. The calculated pressure is 1.071GPa by gt-opx-pl-q geobarometer.
关键词
斜方辉石
成因
地质特征
辉石
blastohypersthene, meta-hypersthene, pyroxene granulite su-bfacies, Taipingzhai of Eastern Hebei Province
