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应用透射电子显微镜 ( TEM)对大别地区英山县含柯石英榴辉岩、石英榴辉岩及石榴角闪岩中石榴子石进行研究 ,结果表明在强塑性变形的三类岩石中 ,石榴子石的超微构造特征存在明显差异。在含柯石英榴辉岩中的石榴子石位错密度比角闪岩中的低。修正石榴子石材料系数 α为 0 .2 5 ,用石榴子石位错密度估算了相对差异应力值 ,并讨论了在超高压榴辉岩形成和退变质过程中各阶段的变质条件。根据石榴子石位错密度测定的差异应力 ,结合石榴子石的变形测量 ,恢复构造三维主应力及构造附加静水压力值 PS,从柯石英相的转变压力 P中减去构造附加静水压力值 PS后 ,利用单纯由重力引起的静水压力值 PG换算上覆岩石的重力和厚度 ,获得大别超高压变质带含柯石英榴辉岩形成深度仅为≥ 32 .0 9～ 32 .1 1 km。因此提出 ,该含柯石英榴辉岩是在这一地壳深处 (或稍深一些 )受强烈构造作用形成的新认识。同位素资料分析表明 ,大别地区榴辉岩系地壳成因 ,这对于榴辉岩是壳内产物的认识提供了进一步证据。
Transmission electron microscopy (TEM) was used to study the cesium garnet from coesite-bearing eclogite, quartz eclogites and amphibolite from the Yingshan County, Dabie area. The results show that among the three types of rocks with strong plastic deformation, pomegranate The ultrastructural features of stone have obvious differences. The dislocation density of garnet in the coesite containing eclogite is lower than that in amphibolite. Correcting the coefficient α of garnet stone material is 0.25, the relative difference stress value is estimated by the dislocation density of garnet, and the metamorphic conditions at various stages during the formation and retrogressive metamorphism of UHP eclogite are discussed. According to the differential stress measured by the dislocation density of garnet and combining with the deformation measurement of garnet, the three-dimensional principal stress and the additional hydrostatic pressure value PS are restored and the additional hydrostatic pressure value PS is subtracted from the transformation pressure P of the coesite phase After the gravity and thickness of overlying rock were calculated by hydrostatic pressure value PG caused by gravity alone, the formation depth of the coesite eclogite in the Dabie UHP metamorphic belt was only 32.09 ~ 32.1 1 km. Therefore, it is suggested that this coesite-bearing eclogite is a new understanding formed by intense tectonics in the deep (or slightly deeper) crust. Isotopic data analysis shows that the eclogites in the Dabie area are the genesis of the crust, which provides further evidence for the understanding that the eclogite is an in-shell product.