大别山双河榴辉岩中石榴石的结构水
Water in garnets of eclogites from Shuanghe, Dabieshan
对大别山双河地区超高压榴辉岩中石榴石的傅立叶变换红外光谱(FTIR)分析显示，石榴石中有两种形式的含氢相: (1) 以OH-缺陷形式赋存在晶体结构中(即结构水); (2) 以H2O的形式存在于可能来自后期退变质阶段的流体包裹体中。结构水的含量达到1759ppm (H2O wt.)。石榴石结构水含量在同一样品不同颗粒间是均一的，而在不同样品间表现出不均一性，不均一分布的特点继承自原岩。石榴石结构水含量与MgO之间表现出良好的正相关，表明其水含量在石榴石形成后没有发生改变。石榴石水含量和MgO之间的正相关可能反映了其玄武岩原岩在结晶分异过程中经历了脱水作用。石榴石水含量的不均一性所暗示的榴辉岩原岩中水的不均一分布说明原岩所经历的水－岩交换可能不是弥散性的；水的不均一性的保存表明超高压变质过程中流体的活动性是非常有限的，而且整个俯冲－折返过程是快速的。
arnets in ultrahigh pressure (UHP) eclogites from Shuanghe in Dabieshan were investigated by Fourier transform infrared spectrometer (FTIR). The results demonstrate that there are two kinds of H speciations in garnets which occurs as OH- point defects in the lattice structure (structural water) and H2O in the submicroscopic liquid inclusions possibly came from the latter stage of retrograde metamorphism. The water contents with up to 1759ppm (H2O wt.) show homogeneity on the samples scale (2×1cm2) and heterogeneity on the outcrops scale (>25m). The water distribution characteristics were inherited from their protoliths. The water contents in garnets showing a good positive correlation with MgO contents possibly reflect the dehydration of basaltic protoliths during the crystallized fraction processes. The heterogeneous distribution of water in the eclogitic protoliths indicate that the water-rock interaction which Shuanghe ecolgites’ protoliths experienced was channeled rather than per
盛英明、夏群科
地质学
结构水 石榴石 红外光谱 双河 大别山
water FTIR garnet Dabieshan
盛英明,夏群科.大别山双河榴辉岩中石榴石的结构水[EB/OL].(2004-06-02)[2025-08-16].http://www.paper.edu.cn/releasepaper/content/200406-7.点此复制
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