Crustal Rheology and Deformation Processes: From Micromechanics to Geodynamics

地壳流变学和变形过程：从微观力学到地球动力学

• 批准号: RGPIN-2014-05712
• 负责人: White, Joseph
• 金额: $ 2.19万
• 依托单位: University of New Brunswick
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=668462
• 关键词: Crustal; Rheology; Deformation; Processes; Micromechanics

The primary objective of the research program is to link the nano-/ micro-scale chemo-mechanical processes that control rock deformation with the macroscopic phenomena that define dynamic behaviour of Earth; that is, to elucidate how interactions of atom- to grain-scale mechanisms mediate plate-scale behaviour. At the core of this research is the first-order relationship of localized deformation, faults and shear zones, to crustal and lithosphere dynamics. Specific topics of focus include: deformation processes associated with high energy tsunamigenic faults; the role of plastic-brittle interactions in determining rock behaviour at the base of the seismogenic zone and the spatio-temporal evolution of fault-fluid interaction during earthquakes, including the formation of economic mineral deposits.* Tectonic and geodynamic behaviour can be examined using a hierarchy comprising geometry, kinematics and process. The specific geometry (structural geology) of a phenomenon provides a global context, deformation history can be determined from the kinematic evolution, and the fundamental control of both of the latter resides in the chemo-mechanical processes. The latter tripartite approach enables robust retention of observations from natural systems. A primary requisite is to establish the context for the phenomena as appropriate e.g. field mapping, determination of fault zone architecture, utilization of the seismicity record. Secondly, material (rocks) from different crustal levels and deformation histories (i.e. different tectonic environments) are thoroughly examined through detailed microstructural and fabric analysis to characterize deformation mechanisms, mineralogical controls and probable rheology. The latter encompasses nanoscience techniques including analytical transmission electron microscopy (EDS, STEM, EELS), electron back-scattered diffraction and laser ICP mass spectroscopy, amongst others, which enable complete materials characterization. Finally, in order to refine and better constrain the natural deformation behaviour, observations are integrated with those of experimental deformation studies. The strength of the nanogeoscience program has the effect of attracting collaboration with experimentalists who require such expertise for analysis of their samples.* The novelty of the research resides in its emphasis on a nano-scale, process-oriented approach that nevertheless remains rooted in classical field structural geology. This bottom-up approach reflects the importance that atom- to grain-scale processes, of necessity operating under far-from-equilibrium conditions, play in the development of emergent properties and structures. In general, the difficulties inherent in predicting fault rupture reflect complex non-linear interactions of chemo-mechanical processes that produce self-organized localization of deformation. To an important extent, the limited predictability of geological phenomena relates to the corresponding limited knowledge of the underlying processes that produce non-deterministic behaviour.* The primary scientific contribution of the research is characterization of the materials and processes that control dynamic behaviour of the earth with all the ensuing implications for short- and long-term behaviour. Zones of localized deformation are inherently fine- to ultrafine-grained, requiring, at the most basic level, high-resolution materials characterization techniques such as TEM; for example, identification of fault products (melts, powders, gels) generated during seismic slip and/or gouge generation that control energy dissipation cannot be fully understood without such analyses. This knowledge can than be included to earthquake hazard assessment and mineral deposit models.

该研究计划的主要目标是将控制岩石变形的纳米/微尺度化学机械过程与定义地球动态行为的宏观现象联系起来；也就是说，阐明原子到晶粒尺度机制的相互作用如何介导板尺度行为。本研究的核心是局部形变、断层和剪切带与地壳和岩石圈动力学的一级关系。具体关注的主题包括：与高能海啸成因断层相关的变形过程；塑性-脆性相互作用在确定发震带底部岩石行为中的作用，以及地震期间断层-流体相互作用的时空演化，包括经济矿床的形成。构造和地球动力学行为可以使用包含几何，运动学和过程的层次结构进行检查。一种现象的特定几何（构造地质学）提供了一个全局背景，变形历史可以从运动学演化中确定，而后者的基本控制都存在于化学-力学过程中。后一种三方面的方法能够对自然系统的观测结果进行稳健的保留。一个主要的必要条件是建立适当的现象背景，例如野外测绘，确定断层带结构，利用地震活动记录。其次，通过详细的微观结构和结构分析，彻底检查来自不同地壳水平和变形历史（即不同构造环境）的物质（岩石），以表征变形机制，矿物学控制和可能的流变学。后者包括纳米科学技术，包括分析透射电子显微镜（EDS， STEM， EELS），电子背散射衍射和激光ICP质谱等，这些技术可以实现完整的材料表征。最后，为了完善和更好地约束自然变形行为，将观测结果与实验变形研究结果相结合。纳米地球科学项目的优势吸引了需要这种专业知识来分析样本的实验家的合作。*这项研究的新颖之处在于它强调纳米尺度的、面向过程的方法，然而它仍然植根于经典的野外构造地质学。这种自下而上的方法反映了原子到颗粒尺度过程的重要性，这种过程必须在远离平衡的条件下运行，在新兴特性和结构的发展中发挥作用。一般来说，预测断层破裂所固有的困难反映了化学-力学过程的复杂非线性相互作用，这些相互作用产生了形变的自组织局部化。在很大程度上，地质现象的有限可预测性与对产生不确定性行为的潜在过程的相应有限知识有关。*这项研究的主要科学贡献是描述控制地球动态行为的材料和过程，以及随之而来的对短期和长期行为的影响。局部变形区本质上是细到超细晶粒的，在最基本的层面上，需要高分辨率的材料表征技术，如TEM；例如，如果没有这样的分析，就无法完全理解地震滑动和/或断层泥生成过程中产生的控制能量耗散的断层产物（熔体、粉末、凝胶）的识别。这些知识可以用于地震危险性评估和矿床模型。