摘要
阜平麻粒岩分布于阜平大柳树和坊里一带的原阜平超群下亚群索家庄组花岗质片麻岩中，以不同规模的透镜体、似层状体产出、麻粒岩主要由石榴石、单斜辉石、斜方辉石、角闪石和斜长石等矿物组成，含有少量的石英。根据岩石的矿物组合和结构特征可将其变质作用演化分为四个阶段：①石榴石中的角门石、斜长石、单斜辉石等变质矿物包体代表峰前阶段；②粗粒平衡共生的角闪石、单斜辉石、石榴石、斜长石±紫苏辉石±石英等代表了峰期变质阶段；③石榴石变斑晶后生合晶反应边中外侧细粒斜方辉石、斜长石和石英集合体代表了峰后变质阶段；④后生合晶反应边中内侧角门石、斜长石等，代表了晚期退化变质阶段。这四个变质阶段演化的Ｐ－Ｔ条件依次为：峰前阶段６３６℃、０．８２４ＧＰａ，峰期阶段７５１～８３３℃、０．８５４～１．０８５ＧＰａ，峰后阶段６７０～７４０℃、０．５５～０．７０ＧＰａ，退化变质阶段６６５℃、０．７２７ＧＰａ，构成了一条顺时针的Ｐ－Ｔ路径，反映了该变质区从早期褶皱增厚到晚期构造抬升的地质动力学过程。
Fuping granulites distribute in Fuping gneiss complex, and correspond to the Suojiazhuang formation of the Fuping supergroup at Daliushu, Fangli and other regions in Fuping county. They occur lens and layered bodies'in different scales. Granulites consist of garnet, clinopyroxene, orthopyroxene, amphibole, plagioclase and a few quartz. Depending on metamorphic textures and reactive relationships among minerals, the evolution of metamorphism can be divided into four stages: ①the pre-peak stage which was represented by mineral inclusions of amphiboles, plagioclase and clinopyroxene in coarse garnet; ② the most principal mineral assemblage which contains coarse grain garnet, amphibole, clinopyroxene, plagioclase、a few hypersthene and quartz; ③ irregular fine grain assemblage of hypersthene, plagioclase and quartz at outer part of symplectic rims around porphyroblasts garnet is the post-peak mineral association; and ④ the fine grain amphibole, plagioclase and quartz at the niller part of the symplectic rim were formed in late retrometamorphic stage. In orders, P-T conditions during the evolution of metamorphism are: 636℃ and 0. 824 Gpa at pre-peak, 751～833℃ and 0. 854～1. 08d Gpa at peak, 670～740℃ and 0. 55～0. 70 Gpa at post-peak, and 665℃ and 0. 727 Gpa at retrometarnorphic stage. They construct a clockwise P-T path, which suggest that this metamorphic terrain had experienced the geodynamic processes from early folding-crust thickening to later tectonic uplifting of the Archean crust.
出处
《高校地质学报》
CAS
CSCD
1996年第1期75-84,共10页
Geological Journal of China Universities
基金
自然科学基金
关键词
麻粒岩
岩石结构
变质演化
P-T路径
granulite, rock texture, evolution of metamorphism, P-T path, Fuping.
