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大别山碧溪岭榴辉岩中有三种含水矿物:多硅白云母、角闪石和黑云母,它们分别是超高压(UHP)阶段(即柯石英榴辉岩相阶段)或者石英榴辉岩相阶段、退变质后成合晶阶段和角闪岩相退变质阶段的产物,本文利用离子探针技术对它们进行了氢同位素和硼同位素的分析。三种矿物内部的同位素组成都是均一的,多硅白云母的δD为-105‰±9‰,δ~(11)B为-25.9‰±2.0‰;角闪石的δD为-100‰±9‰,δ~(11)B为-24.4‰±0.9‰;黑云母的δD为-65‰±4‰,δ~(11)B为-19.3‰±1.3‰。多硅白云母和角闪石的氢-硼同位素组成在误差范围内是相同的,而和黑云母则有明显的差别,这表明,从UHP阶段或者石英榴辉岩相阶段到随后的后成合晶阶段,变质流体是内部缓冲的,而在角闪岩相变质阶段,则有了外来流体的加入,这个流体是相对富集D和~(11)B的。碧溪岭榴辉岩矿物相对于其地壳原岩表现出低δ~(11)B的特征,说明俯冲过程中板块经历了强烈的脱硼。
There are three types of hydrous minerals in the Bixi Ling eclogite in the Dabie Mountains: poly-silica mica, amphibole and biotite, which are UHP stage (ie, coesite eclogite facies) or quartz eclogite facies , Metamorphism after degenerate metamorphism and amphibolite facies metamorphism stage of the product, the use of ion probe technology for their hydrogen isotope and boron isotope analysis. The isotopic composition of the three minerals are uniform, the δD of phengite is -105 ‰ ± 9 ‰, δ ~ (11) B is -25.9 ‰ ± 2.0 ‰, and the amphibole δD is -100 ‰ ± 9 ‰, δ ~ (11) B is -24.4 ‰ ± 0.9 ‰, δD of biotite is -65 ‰ ± 4 ‰, and δ ~ (11) B is -19.3 ‰ ± 1.3 ‰. The hydrogen-boron isotopic compositions of picei and amphibole are the same within the error range and markedly different from that of biotite, indicating that from the UHP stage or from the quartz eclogite facies to the subsequent post-synthesis The metamorphic fluid is internally buffered, whereas in the amphibolite facies metamorphism, an extraneous fluid is added. This fluid is relatively enriched in D and ~ (11) B. The Bixi Ling eclogite mineral shows a low δ ~ (11) B relative to its crustal protolith, indicating that the plate underwent strong deboronization during subduction.