大陆碰撞和超高压变质研究:进展和展望

A retrospective and perspective view on continental collision and ultrahigh-pressure metamorphism

在原岩为大陆地壳的高级变质岩中发现柯石英和金刚石这类超高压标志矿物,使人们认识到低密度大陆地壳曾经俯冲到大于80 km的地幔深部,是20世纪末大陆动力学研究的最大进展,因此革新了板块构造理论.大陆碰撞和超高压变质研究已成为21世纪发展板块构造理论的前沿和核心课题.大别-苏鲁造山带出露有世界上最大的超高压变质构造单元,中国科学家以此为基地,在大陆碰撞和超高压变质的一些重要领域取得了国际上有影响力的系列成果.这些包括大陆地壳俯冲的深度和规模、大陆深俯冲过程的时间序列、大陆碰撞过程中的流体活动、深俯冲陆壳的流变学特征等.本文评述了大陆地壳经历深俯冲的矿物学记录,概括了近年来大别-苏鲁造山带研究的突出进展,从四个方面对大陆碰撞和超高压变质研究进行了展望:①超高压变质带的构造-变质演化,②大陆碰撞过程中的流体活动,③大陆碰撞带数值模型,④超高压变质矿物微区分析的新技术.

Because such ultrahigh-pressure （ UHP ） index minerals as coesite and diamond were found in high-grade metamorphic rocks of continental crust origin, it was recognized that the continental crust of low density was subducted to mantle depths over 80 km. This is the greatest progress in the studies of continental dynamics during the last 20th century, leading to the revolution of plate tectonics theory. Studies of continental collision and UHP metamorphism have been the forefront and key projects to develop the plate tectonics theory in 21st century. In particular, UHP lithotectonic outcrop in the DabieSulu orogenic belt is the largest one in the world and thus has been the typical locality for this purpose, which enables Chinese scientists to make a series of achievements in various fields of continental collision and UHP metamorphism. These achievements include the depth and scale of continental subduction, the temporal sequence of subduction processes, the fluid activity in collision processes, and the rheology of deeply subducted crust. A review on mineralogical records of continental deep subduction, and an outline of outstanding advances in studies of the Dabie-Sulu orogenic belt. A perspective was given from the following four aspects： （1） tectono-metamorphic development of UHP metamorphic belts, （2） fluid-rock interaction during continental collision, （3） numerical modeling of continental collision, and （4） advanced instrumental technologies applied to microdomains in UHP minerals.