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超高压变质岩是大陆深俯冲作用的产物。超高压变质岩在深俯冲和快速折返过程中,经历了长距离地构造搬运和构造力的作用。其构造变形主要集中在韧性剪切带中,并发生强烈地塑性流变。研究超高压变质构造岩的显微构造及其变形机制对于深入了解大陆壳岩石在深俯冲过程中的流变学行为有十分重要的意义,山东仰口的超高压韧性剪切带中榴辉岩质和花岗质糜棱岩记录了超高压变形的历史。在超高压条件下的稳定矿物绿辉石、多硅白云母、兰晶石和钾长石具有不规则波状消光、亚晶界、核幔构造和动态重结晶等显微构造特征,TEM 研究揭示了大量的位错构造,表明位错蠕变是其主要的变形机制。在花岗质糜棱岩中,金红石在刚性矿物的压力影中沉积,细粒的石榴石条带平行片理延伸,都说明超高压变形过程中有流体存在,流体助力的物质扩散迁移是又一个重要的变形机制。依据现有的流变学定律估算的流变应力应该在几十兆帕以上。
EHR metamorphic rocks are the product of deep subduction in the continent. Ultrahigh-pressure metamorphic rocks have undergone a long-term structural handling and tectonic force during deep subduction and rapid reentry. Its structural deformation is mainly concentrated in the ductile shear zone and intense plastic rheology occurs. It is of great significance to study the microstructure and deformation mechanism of ultrahigh-pressure metamorphic tectonic rocks in order to understand deeply the rheological behavior of continental crust during deep subduction. Eclogites Metamorphic and granitic mylonites record the history of UHP deformation. Stable minerals omphacite, pheismite, garnet and potash feldspar under ultra-high pressure have microscopic structural features such as irregular wavy extinction, subgrain boundaries, core-mantle structure and dynamic recrystallization. TEM studies reveal that A large number of dislocation structures indicate that dislocation creep is the main deformation mechanism. In granitic mylonites, rutile deposits in the pressure shadow of rigid minerals and fine-grained garnet bands extend in a piecewise manner, both of which indicate the presence of fluid during the deformation process of the UHVDC. An important deformation mechanism. The rheological stress estimated based on the current rheological law should be above tens of megapascals.