大别地块超高压变质省的构造变形研究

STUDY ON TECTONIC DEFORMATION OF UHP METAMORPHIC PROVINCE IN DABIE MASSIF, CHINA

构造解析的基本目的是建立构造事件造成的地质体几何学、运动学、动力学和流变学。大陆碰撞造山带内含柯石英及微粒金刚石等矿物组合的超高压（ＵＨＰ） 变质岩的形成和折返，是极为复杂的地球动力学过程。与世界上已知大多数超高压变质带相似，中国大别地块内超高压变质省现今观察到的主体构造形式，主要是在碰撞或超高压变质峰期后伸展体制下形成的。通过对大别超高压变质省内伸展组构及挤压（ 碰撞） 组构的鉴别、分析，结合有关超高压变质带构造学研究领域的简略综述指出，在揭示超高压变质带的形成及折返动力学过程中。

The fundamental aim of tectonic analysis is to establish the geometry, kinematics, dynamics and rheology of rocks during tectonic events on all scales. The formation and exhumation of ultra high pressure (UHP) metamorphic rocks in continental collision belts are generally caused by extremely complicated tectonic processes. According to the main principles of the analytical tectonics or tectonic analysis, the regional structural kinematic and rheologic analyses of UHP metamorphic province in Dabie massif may give abundant evidences to reveal multiphase tectonic deformation of the rocks. The most striking fabrics and structures in UHP metamorphic province were formed as a result of the post Indosinian collisional extension, which led to the development of structures similar to those of the metamorphic core complexes. The structures related to the collision and initial exhumation process are presented in the form of variously modified shear zones and remnants of the syn UHP metamorphic fabrics. The discussion is concentrated on the processes related to the exhumation of UHP metamorphic rocks. The exhumation of UHP metamorphic rocks from depths of as great as 100km or more to the surface was at least in part due to the crustal extension under amphibolite facies conditions. The paper also outlines the main unresolved tectonic key problems such as the location of the collisional suture belt, the role of partial melting of the crustal rocks and how to construct a model for the formation and exhumation of UHP metamorphic rocks as well. The reasonable explanation of these problems aforementioned may contribute to the study of geodynamic processes for continental collision orogenic belts.