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角闪石作为福建东山坑北复式岩体的主要变质特征矿物之一,其详细的成因矿物学研究对解释该套岩体的变质变形特征和条件具有一定的指导意义。本文应用电子探针分析和斜长石-角闪石温压计、黑云母-石榴子石温压计对该区花岗岩中蓝绿色角闪石进行了成分分析和温压条件的研究。研究表明该区变质变形花岗岩中蓝绿色角闪石为铁浅闪石,大部分为岩浆结晶和次生交代的角闪石。通过斜长石-角闪石温压计计算得出其压力为0.40-0.72 GPa,变质温度大约为543-557℃。通过石榴石-黑云母温度计计算其变质温度为546-590℃。角闪石的成因矿物学研究表明坑北岩体的变质程度为低角闪岩相-高绿片岩相。变质作用相当于燕山造山运动的第Ⅲ幕,是与深大断裂有关的低压高温型区域。
Amphibole, as one of the main metamorphic minerals in the North Porphyry complex of Dongshan, Fujian Province, has a certain guiding significance for the study of its genesis and mineralogy to explain the characteristics and conditions of metamorphism and deformation of this set of rock masses. In this paper, component analysis and temperature-pressure conditions of blue-green hornblende in granite in this area were studied by using electronic probe analysis, plagioclase-amphibolite thermometer and biotite-garnet thermometer. The study shows that the blue-green hornblende in the metamorphic deformable granite in this area is iron amphibole, most of which are amphibole from magma crystallization and secondary replacement. The plagioclase-amphibolite thermometer was used to calculate the pressure of 0.40-0.72 GPa, and the metamorphic temperature was about 543-557 ℃. The metamorphic temperature was 546-590 ℃ by garnet-biotite thermometer. The genetic mineralogy of amphibole indicates that the metamorphic degree of the karst northern pluton is low amphibolite facies-high greenschist facies. The metamorphism is equivalent to the third act of the Yanshan orogeny and is a region of low pressure and high temperature associated with deep faults.