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麻粒岩相条件下石榴黑云斜长片麻岩实验结果表明,含水矿物黑云母(Bi)脱水熔融、长英质矿物部分熔融的性质主要受控于温度条件;而矿物相转变不仅受控于温压条件,而且与脱水熔融、部分熔融存在密切成因联系。依据Bi脱水熔融性质和石榴石(Gi)转变反应特征,可划分以下三个阶段:(1)当温度在700℃时,Bi转变为钛铁矿(Ilm)+磁铁矿(Mt)+H_2O,Gt转变为Mt,(2)当温度在730—760℃,Bi脱水熔融为富K_2O熔体(Melt)+Ilm+Mt,Gt转变为紫苏辉石(Hy)+堇青石(Crd);(3)当温度大于790℃时,Bi脱水熔融为Melt+Hy+Ilm+Mt+H_2O,Gt则转变为Hy+尖晶石(Sp)+Crd组合。熔体比例和熔体演化特征除受温压条件控制外,与长英质矿物部分熔融程度和脱水熔融性质关系密切。实验结果显示,在麻粒岩相变质作用以及与其相伴随的重熔作用(或区域性混合岩化作用)过程中,不仅存在传统的固相+固相(或流体相)的反应和脱水熔融反应,而且存在熔体参与的变质反应(即:未熔矿物与熔体之间的反应)。该项实验对深入探讨麻粒岩相矿物演化的成因机制及其动力学意义提供可靠的实验依据。
The experimental results of granulite-biotite plagioclase gneiss show that the biofacies of biotite (Bi) are dehydrated and melted, and the properties of partially melted feldspar are controlled mainly by the temperature. The transformation of the mineral phase is not only controlled In the temperature and pressure conditions, but also with the dehydration melting, partial melting there is a close genetic relationship. According to the dehydration melting properties of Bi and the reaction characteristics of garnet (Gi) transformation, the following three stages can be divided: (1) Bi is transformed into Ilm + Mt + H 2 O at 700 ℃, , Gt is changed to Mt, (2) When the temperature is 730-760 ℃, Bi is dehydrated and melted into K 2 O melt (Melt) + Ilm + Mt, and Gt is transformed into Hy + cordierite (Crd) (3) When the temperature is above 790 ℃, Bi dehydrates and melts into Melt + Hy + Ilm + Mt + H_2O and Gt into Hy + Sp + Crd. In addition to being controlled by temperature and pressure, the melt fraction and melt evolution characteristics are closely related to the partial melting degree and dehydration-melting properties of feldspar minerals. The experimental results show that during the granulite facies metamorphism and its accompanying remelting (or regional mixed lithification), there are not only the reaction of solid phase and solid phase (or fluid phase) and dehydration melting Reaction, and there is a metamorphic reaction involving the melt (ie, the reaction between the unmelted mineral and the melt). The experiment provides a reliable experimental basis for further exploration of the genetic mechanism of granulite-facies mineral evolution and its kinetic significance.