摘要
根据对表壳岩、中酸性侵入岩和基性岩墙的变质变形作用及相互关系的深入研究,确定冀东麻粒岩相区在早前寒武纪时期主要经历了两期变质作用,每期变质作用均经历了一个长期的演化过程,峰期阶段的变质条件均达到了麻粒岩相。第一期变质作用(3000～2500Ma)的PTt演化具近等压冷却(IBC)特点的逆时针轨迹,第二期变质作用(2300～2000Ma)是近等压加热(IBH)特点的顺时针轨迹,反映两期变质作用具有不同的构造环境和演化过程。
Basing on the metamorphic characteristics of supercrustal rocks, intermediate-acidic intrusive bodies and mafic dyke swarms and their relationships, the authors propose that granulite facies terrane in eastern Hebei Province underwent two periods of metamorphism, each of which has its own evolutional process and can be divided into three or four stages. Peak metamorphism in the periods produced granulite facies, but the P-T-t paths are diferent. For the first period of metamorphism an anticlockwise path is characterized by near-isobaric cooling(IBC), for the other period a clockwise pathby near-isobaric heating(IBH). It indicates that the two periods of metamorphism were present in different tectonic setting and geologic evolution. The relations between various geological processes, together with radiometric dating, indicate that the first period of metamorphism was present at about 3000～2500 Ma, and the second at about 2300～2000 Ma.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
1992年第2期128-135,T002,共9页
Acta Petrologica Sinica
关键词
变质作用
PTT轨迹
麻粒岩
变质作用
Metamorphism
P-T-t paths
Granulite facies terrane
Mineral generations
