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出露于造山带的高压-超高压榴辉岩记录了地壳俯冲到地幔深度而后又折返回地表的过程,其俯冲过程与折返机制的研究对理解俯冲带性质、演化、地球动力学过程乃至板块构造理论都有着非常重要的作用.相对于较轻的陆壳长英质高压-超高压岩石,基性洋壳榴辉岩密度大,其折返难度大且过程复杂.折返过程除了受内在浮力的影响,还受外在构造力(如隧道流)的制约,另外板片构造环境(如板片后撤和板片断离)的作用也不可忽视.中国西南天山高压-超高压变质带是典型的经历过深俯冲变质作用的增生混杂岩带,主要由高压-超高压变质沉积岩及夹杂其中的变基性岩透镜体组成,但长期以来其折返模式一直不太清楚.根据其野外产状、岩相学特征、峰期变质温压条件和峰期变质年龄等多方面的综合分析,可以采用沉积岩型“俯冲隧道折返模式”来概括西南天山高压-超高压变质带的形成和演化.部分经历多期变质作用的榴辉岩岩块记录了多期俯冲-折返循环,反映了俯冲隧道内的上下环流运动,有力证明了俯冲隧道的存在.最后,本文对目前研究存在的问题和未来的探索方向进行了展望.
The UHP-UHP eclogites exposed in the orogenic belt record the subduction of the crust to the depth of the mantle and then return to the earth’s surface again. The study on the subduction process and reentry mechanism is of great help in understanding the properties of the subduction zone, evolution, geodynamics, Tectonic theory has a very important role.Compared with the lighter continental crust of high pressure - high pressure rock, the basic oceanic crust eclogite high density, the difficulty of reentry and complex process.Return to the process in addition to the internal buoyancy , But also by external tectonic forces (such as tunnel flow), and the role of plate tectonic setting (such as plate retreat and plate detachment) can not be neglected. The Tianshan high pressure-ultrahigh pressure metamorphic belt in southwest China is a typical The accretionary melange belt experienced deep subduction and metamorphism is mainly composed of high pressure-ultrahigh-pressure metamorphic sedimentary rocks and metamorphic lithocarbon lens inclusions, but it has not been clear for a long time that its reappearing pattern is still unclear.According to its field production, Facies characteristics, peak metamorphic temperature and pressure conditions and peak age of metamorphism, we can use the sedimentary rock type “subduction tunnel reentry model ” to summarize the high pressure in Southwest Tianshan - high The formation and evolution of the compressional metamorphic belt The eclogite blocks that undergone multi-metamorphism recorded multiple periods of subduction-reentry cycles, which reflected the up-down circulation in subducted tunnels, which proved the existence of subducted tunnels.Finally, The current research problems and future exploration direction are prospected.