摘要
宣化-赤城的高压麻粒岩带的变质泥质岩中存在“蓝晶石+正条纹长石”的特征高压组合,形成条件为P≥1.0GPa,表明变质泥质岩同变质基性岩一样经历了高压麻粒岩相变质作用。
Kyanite-garnet gneiss and graphite-bearing garnet gneiss(with kyanite) are interlayers in the Xuanhua-Chicheng high-pressure granulite belt. The mineral assemblages of the kyanite-garnet gneiss from early stage to late-stage are kynit e + K - feld spar (Perthite ) + gamet + rutlie + granitic melt (L ) and garnet + micro-cline + muscovite + plagioclase + albite + quartz±sillima n lie. The coexiting assemblages of Ky + Per and Grt + Ky+Rut are high pressure indicators. According to the following metamorphic reactions: K y + Per + melt→Mus +PI+Qz + Sil and Ky + Per + H2O→Mus+Qz, we abtained that the peak metamorphic condition of the politic rock is 900℃ >T>825℃, p≥1. 0 GPa. The mineral assemblages of the kyanite-garnet gneiss represent that of the Saxen and Barrow types respectively, showing that there is pressure decreasing from early to late regional metamorphism. The high-pressure assemblages of the politic rocks in the Xuanhua-Chicheng high-pressure granulite belt show that the politic rocks had also undergone the high-pressure metamorphism, same as the basic granulite. It might be part of the lower crust and exposed through collision and overthrusting of the Archean microterranes.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
1995年第3期273-278,共6页
Acta Petrologica Sinica
基金
国家教委博士点基金
关键词
麻粒岩
蓝晶石
正条纹长石
地质意义
High-pressure granulite
Kyanite
Perthite
Hebei Privince
Xuanhua