论文部分内容阅读
运用电子背散射衍射技术研究了天然超高压榴辉岩中石榴石和绿辉石的变形晶格优选方位与其结构水之间的关系,并探讨了榴辉岩的主要塑性变形机制.研究结果表明:(1)天然榴辉岩中富结构水的绿辉石具有典型的L或SL型组构,[001]轴极点在面理面上呈大圆环分布,最大极密对应轴向近平行线理,(010)面极点为垂直线理分布的大圆环,最大极密对应晶面近平行面理,表征在剪切为主变形条件下形成;绿辉石中结构水含量变化不会导致绿辉石变形组构特征大的变化,即不改变变形机制和位错主滑移系,但可能是造成绿辉石低流变强度的主因;(2)榴辉岩中结构水含量变化可以造成石榴石流变性质的重大转变,在无水条件下石榴石显刚性,在富结构水条件下颗粒边界过程将主导石榴石的塑性变形并导致流变强度的下降,在这两种情况下石榴石都不显示晶格变形优选方位.该研究成果对深入了解榴辉岩在深俯冲和折返过程中的变形过程和机制及相关的流体活动具有重要意义.
The electron backscatter diffraction technique was used to study the relationship between the preferred orientation of the deformed lattice of garnet and omphacite in natural ultrahigh-pressure eclogites and its structural water and the main plastic deformation mechanism of the eclogites was discussed.The results show that: (1) The omphacite rich in structural water in natural eclogites has a typical L or SL type structure. The [001] axis pole has a large circular ring distribution on the plane of the plane, and the maximum and the extreme are corresponding to the axial parallel lines (010) Poles are vertical rings and the maximum and maximum are close to the crystal plane. The characterization is formed under the condition of shear deformation. The structural water content in omphacite will not lead to green Large changes in the structural features of pyroxene deformation, that is, without changing the deformation mechanism and dislocation of the main slip system, but may be the main cause of the low rheological strength of omphacite; (2) eclogite structural water content changes can cause A significant shift in the rheological properties of garnets is the apparent rigidity of the garnet under anhydrous conditions. The grain boundary process under plasticized water conditions will dominate the plastic deformation of the garnet and result in a loss of rheological strength. In both cases, the pomegranate The stone does not show the preferred orientation of lattice deformation Fruit important for understanding of the deformation process and mechanisms of fluid and related activities eclogite in deep subduction and exhumation process.