【摘要】 在丹凤群中,部分斜长角闪岩含有由阳起石内核和镁普通角闪石外环组成的环带角闪石。外环形成于主变质期,而内核是早期变质矿物的残余。早期变质作用属低压相系的斜长石-阳起石相环境,发生在丹凤群形成之初;而主期变质发生在加里东晚期的中压相系的角闪岩相。大约在海西—印支期后又出现了伴随韧性剪切作用的退变质现象。早期变质和主期变质作用可能分别与秦岭造山带的裂谷作用和裂谷闭合过程有关。更多还原

【Abstract】 The amphiboles with the zonal structure are found in the Danfeng Group.The inner core of the zone is made of actinolite and its rim of magnesio which was formed during the main phase of metamorphism. The inner core is the relic minerals of the earlier phase matamorphism. The earlier phase metamorphism belongs to the actinolite plagio-clase facies of the low pressure facies series and the main phase metamorphism occurred in the amphibolite facies of the middle pressure facies sequence. It is possible that the earlier phase metamorphism took place just later than the formation age of the Danfeng Group, and the main phase metamorphism occurred during the later Caledon ian.The retrograde metamorphism along the deformation belts took place just after the Hercynian-Indo-China metamorphism. It would be; possible that the earlier and main phase metamorphism was related with the rifting and closing processes of the rift in the Qinling Orogen.更多还原