Rheology and seismic properties of polyphase rocks

多相岩石的流变学和地震特性

• 批准号: RGPIN-2016-06408
• 负责人: Ji, Shaocheng
• 金额: $ 2.11万
• 依托单位: École Polytechnique de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=616289
• 关键词: Rheology; seismic; properties; polyphase; rocks

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.

我的研究计划的长期目标是提高我们对岩石圈中多矿物岩石的变形行为，流变学和地震特性的理解，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。近期目标主要有两个方面：（1）亚稳多矿物岩石的流变学和地震学性质。岩石圈内岩石的变质作用常以远离平衡变质作用为主，并受差应力作用下流体介导的输运过程控制。绘制岩石圈内不平衡变质作用的程度，这必然会导致地球科学思想的重大变化，前提是需要了解流体介导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）。我们将对中国大别-苏鲁造山带的高压和超高压榴辉岩和橄榄岩及其退变质岩石（深钻岩心样品和关键地表露头）进行野外测绘、结构分析、显微结构（TEM、SEM、EBSD和FTIR）、岩石物理学（高压测量）和流变学（HT-HP实验变形）的创新性协同研究。(2)壳幔过渡带的流变学和地震学特征。尽管2009年标志着莫霍面发现一个世纪，但其确切性质、起源和在造山过程中的作用仍然是地球动力学中一个尚未解决的重大问题，因为现今大陆下方的CMT远不容易接近。一种新的方法是仔细研究这种CMT区的表面暴露的、挖出的横截面（即，榆树沟-通化山一带），代表南天山北方陆内逆冲剪切带的挤压隆起，由层间片理化镁铁质麻粒岩和橄榄岩沿沿着陆内逆冲剪切带挤入绿片岩-下角闪岩相中地壳变质沉积物中。研究结果将对更好地了解世界其他地区莫霍面的地震特性和各向异性、成分、流变学和结构产生广泛的影响和创新性贡献，并最终改善对莫霍面在板块构造和大陆演化中作用的评估。拟议的计划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。