Rheology and seismic properties of polyphase rocks

我的研究计划的长期目标是提高我们对岩石圈多矿物岩石的变形行为、流变学和地震性质的理解，并将改进的知识应用于纯地球科学和应用地球科学中的真正问题。短期目标主要有两个方面：(1)亚稳多矿质岩石的流变学和地震性质。岩石圈中岩石的变质作用往往受远离平衡和差应力作用下流体介质输运过程的控制。绘制岩石圈内的不平衡变质程度，这必须导致地球科学思想的重大变化，前提是了解流体中介的相变如何影响物理上可观察到的量(例如，地震波的速度、各向异性和衰减)。中国，我们将对大别-苏鲁造山带高压、超高压榴辉岩和橄榄岩及其退变变质岩(深部钻芯样品和关键地表露头)的野外填图、结构分析、微观结构(透射电子显微镜、扫描电子显微镜、EBSD和FTIR)、岩石物理(高压测量)和流变学(高温高压实验变形)进行创新性、协同性的研究。(2)壳幔转换带的流变学和地震性质。虽然2009年是莫霍面发现一个世纪以来的一年，但它的确切性质、起源和在造山过程中的作用仍然是地球动力学中的一个重大悬而未决的问题，因为今天大陆下的CMT远没有那么容易获得。一种新的方法是仔细研究这样一个CMT带(即新疆玉树沟-通化山地块，中国西北部)的地表暴露剖面，它代表了南天山北缘沿陆内逆冲剪切带由层间叶状镁铁质麻粒岩和橄榄岩挤压成绿片岩到下角闪岩相中地壳变质岩的挤压隆起。研究成果将对更好地了解世界其他地区莫霍面的地震性质和各向异性、成分、流变性和结构产生广泛的影响和创新性的贡献，并最终改善对莫霍面在板块构造和大陆演化中的作用的评估。拟议的课程也有一个重要的教育组成部分，因为学生从具有挑战性的跨学科研究中受益。

The long-term goals of my research program are to improve our understanding of deformation behavior, rheology and seismic properties of polymineralic rocks in lithosphere, and to apply the improved knowledge to genuine problems in pure and applied Earth Sciences. The short-term objectives are mainly two-fold: (1) Rheology and seismic properties of metastable polymineralic rocks. Metamorphism of rocks in the lithosphere is often dominated by far-from-equilibrium and controlled by fluid-mediated transport processes under differential stress. Mapping the degree of disequilibrium metamorphism within the lithosphere, which must lead to significant changes in thought in geosciences, pre-requires the understanding of how fluid-mediated phase transformation affects physically observable quantities (e.g., velocities, anisotropy and attenuation of seismic waves). We will perform an innovative, concerted study of field mapping, structural analysis, microstructures (TEM, SEM, EBSD and FTIR), petrophysics (measurements at high pressures) and rheology (HT-HP experimental deformation) of HP and UHP eclogites and peridotites as well as their retrograde metamorphic rocks from the Dabie-Sulu orogenic belt (deep drill core samples and key surface outcrops), China. (2) Rheology and seismic properties of the crust-mantle transition (CMT) zone. Although the year 2009 marked one century since the discovery of the Moho, its exact nature, origin and role in orogenic processes remain a major unresolved issue in geodynamics since the CMT beneath the present-day continents is far less accessible. A novel approach is to investigate carefully a surface-exposed, exhumed cross section of such a CMT zone (i.e., the Yushugou-Tonghuashan massif, Xinjiang, Northwest China) which represents a compressional uplift consisting of interlayered foliated mafic granulites and peridotites extruded into greenschist to lower amphibolite-facies middle crustal metasediments along intracontinental thrust shear zones at the northern margin of the South Tianshan. The research results will promise broad impacts and innovative contributions to the better understanding of seismic properties and anisotropy, composition, rheology and structure of the Moho in other parts of the world, and ultimately improve assessment of the Moho’s role in the plate tectonics and continental evolution. The proposed program has also an important educational component as the students benefit from challenging interdisciplinary research.