摘要
大别山超高压片麻岩与正常（中低压）片麻岩呈互层状产生，原岩相当于安山质火山岩。超高压片麻岩的特征矿物组合为石榴子石＋绿辉石＋多硅白云母＋斜黝帘石＋石英／柯石英＋金红石±蓝晶石±纳云母，高压矿物包体、冠状反应结构、假象结构和局部不平衡结构可作为其岩相学鉴别标志。它们经历了与含柯石英榴辉岩可对比的超高压变质（＞2．7GPa、672～725℃）和中低压绿帘角闪岩相退变质（0．3～0．7GPa、450～520℃）两个主要演化阶段，其退变质作用与围岩区域变质作用的一致性有可能说明二者自始至终经历了同一演化过程。
Ultrahigh-pressure gneiss derived from andesitic volcanic rocks occurs as interlayers with common nedium-low-pressure gneiss in the Dabie Mountains.It contain a diagnostic ultrahigh-pressure mineral assemblage of garnet+omphzcite(pseukomorph)+phengite+clinozoisite+quartz/coesite+rutile±kyanite±paragonite.Various high-puessure mineral inclusions in garnetor relics in the matrix and corana,pseudomorph and local disequilibrium textuies can be regarded as a petrographic indicator to distinguish ultrahigh-pressur gneiss from common gneiss.Similar to coesite-bearing eclogite,ultrahigh-pressure gneiss experienced two evolutional stages of ultrahigh-pressure metamorphism(〉2.7Gpa,672～725C)and retrograde medium-low-pressure metamouphism under epidote amphiboite facies conditions (0.3～0.7GPa,450～520C).The correlation between the retrograde metamorphism of ultrahigh-pressure rocks and regional metaorphism of their country rocks may imply that the two kinds of rocks underwent an identical ebolutional process from the beginning to the end.
出处
《矿物学报》
CAS
CSCD
北大核心
1995年第2期154-162,T001,共10页
Acta Mineralogica Sinica
关键词
片麻岩
超高压
岩石学
变质演化
gneiss
ultrahigh-pressure retrograde metamorphism
the Dabie Mountains
