大陆中部地壳应变局部化与应变弱化

发布时间：2018-04-03 06:29

本文选题：岩石圈流变学　切入点：中部地壳　出处：《岩石学报》2017年06期

【摘要】：大陆岩石圈流变学研究是构造地质学学科发展的必然,也是发展板块构造理论、探索大陆板块内部变形与动力学演化的核心问题。大陆中部地壳是大陆岩石圈中一个具有特殊性的圈层,其主要成分以花岗质岩石为代表,位于岩石脆-韧性转变域。在中部地壳层次上,岩石既具有脆性变形特点,又具有韧性变形属性,而且常常表现出多种流变强度。研究成果显示,中部地壳岩石流变具有许多特殊性:1)应变局部化是中部地壳流动最为典型表现形式;2)存在大陆地壳多震层:多震与强震,显示出中部地壳既弱又强的流变学属性;3)液/岩反应强烈,流体相直接影响着岩石的流变性;4)在许多地区存在有地球物理异常体(低速高导体)。大陆中部地壳应变局部化是板块相互作用过程中地壳层次上应变积累与集中的重要表现。在宏观尺度、中小型尺度和微观尺度上都有着重要的构造特点。地壳岩石的应变弱化,是诱发应变局部化的主要机制。多种形式的水致弱化(包括液压致裂、反应弱化、水解弱化等)与结构弱化(包括细粒化、晶格取向、成分分带性等)对于应变局部化具有重要的贡献。大陆地壳岩石流变学、中部地壳弱化与应变局部化研究,是未来岩石圈流变学研究的重要方向。
[Abstract]:The study of continental lithospheric rheology is the necessity of the development of tectonic geology and the core of the development of plate tectonics theory and the exploration of deformation and dynamic evolution within the continental plate.The central continental crust is a special layer in the continental lithosphere, which is mainly composed of granitic rocks and is located in the brittle ductile transition region of rocks.In the middle crustal layer, the rock is characterized by brittle deformation and ductile deformation, and often shows a variety of rheological strength.The results show that the rheology of the central crustal rocks has many particularities: 1) strain localization is the most typical form of crustal flow in the middle part of the earth's crust, and (2) there are multi-earthquake layers in the continental crust: multiple earthquakes and strong earthquakes.It is shown that the weak and strong rheological properties of the central crust are strong fluid / rock reaction and fluid facies directly affect the rheological variability of rocks. There are geophysical anomalies (low velocity and high conductors) in many areas.The crustal strain localization in the middle part of the continent is an important manifestation of strain accumulation and concentration at the crustal level in the course of plate interaction.There are important structural characteristics in macro scale, medium scale scale and micro scale.Strain weakening of crustal rocks is the main mechanism of strain localization.Various forms of water induced weakening (including hydraulic cracking, reaction weakening, hydrolysis weakening, etc.) and structural weakening (including fine granulation, lattice orientation, composition zonation, etc.) have important contributions to strain localization.The study of lithology in the continental crust, the weakening of the crust and strain localization in the middle part of the earth's crust is an important research direction of lithospheric rheology in the future.
【作者单位】：中国地质大学地质过程与矿产资源国家重点实验室;
【基金】：国家自然科学基金项目(41430211、41172190)资助
【分类号】：P542

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