Conditions, rates and mechanisms of fundamental metamorphic processes

基本变质过程的条件、速率和机制

• 批准号: RGPIN-2015-03829
• 负责人: Gaidies, Fred
• 金额: $ 1.97万
• 依托单位: Carleton University
• 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=651412
• 关键词: Conditions; rates; mechanisms; fundamental; metamorphic

The origin of rock texture and microstructure is one of the least understood aspects of metamorphic petrology. Yet it is known that it drastically influences some of the most elemental properties of Earth's crust such as its behavior during plastic deformation, the way it transmits seismic waves, or the rate with which thermal anomalies form and dissipate in response to tectonic processes. Funding is requested for research that will lead to a new level of understanding of the fundamental processes that govern the formation of rock texture and microstructure. This research will integrate detailed petrographic and geochronological investigations with equilibrium and kinetic modelling to quantify the rates and pressure, temperature and chemical conditions of these fundamental processes that include nucleation, crystal growth, diffusion and mineral dissolution.***In the past, an approach to chemical equilibrium was utilized to estimate the conditions of rock formation. However, recent research by the applicant and coworkers induced the question whether the disequilibrium required for rock-forming processes may be larger than previously assumed which would have important implications for the way rock-forming conditions are estimated and how these estimates are interpreted. A particular focus of the proposed research will be to quantify the departure from chemical equilibrium required for metamorphic processes, and how this depends on the interplay of interface and strain energy and directed stress and metamorphic mineral reaction kinetics. This research will help to evaluate and develop new constraints on important tectonic processes ranging from the nature and rates of mountain belt formation to the mechanisms of flow of semi-viscous rocks in Earth's mid-crust.***Major questions to be addressed by the research are: (1) What is the order of magnitude of the key parameters that impact on rock texture and microstructure formation? (2) How are these key parameters related to each other and how do they depend on changes of the metamorphic environment during geological processes? (3) What is the link between these parameters, rock microstructure, and large-scale tectonic processes? Research on the interplay and magnitudes of the key parameters for rock microstructure formation is still in its infancy but required to advance our understanding of the role of chemical reaction kinetics in geological systems. The proposed research will increase the competitiveness of Canada's earth science sector contributing to public's intrinsic interest in minerals and rocks and how they form. Direct applications of that research will provide links to the resource extraction industries which form an important segment of the Canadian economy.**

岩石结构和显微构造的起源是变质岩石学中最不为人所知的方面之一。然而，众所周知，它极大地影响了地壳的一些最基本的特性，例如它在塑性变形期间的行为，它传输地震波的方式，或者热异常形成和消散的速率。要求提供资金的研究，将导致一个新的水平的理解的基本过程，管理岩石结构和微观结构的形成。这项研究将把详细的岩相学和地质年代学调查与平衡和动力学建模相结合，以量化这些基本过程的速率和压力、温度和化学条件，包括成核、晶体生长、扩散和矿物溶解。在过去，化学平衡的方法被用来估计岩石形成的条件。然而，申请人及其同事最近的研究引发了一个问题，即岩石形成过程所需的不平衡是否可能大于先前假设的不平衡，这将对估计岩石形成条件的方式以及如何解释这些估计产生重要影响。拟议的研究的一个特别重点将是量化偏离所需的变质过程的化学平衡，以及这如何取决于界面和应变能和定向应力和变质矿物反应动力学的相互作用。这项研究将有助于评估和开发对重要构造过程的新约束，从山带形成的性质和速率到地球中地壳半粘性岩石流动的机制。研究的主要问题是：（1）影响岩石结构和微结构形成的关键参数的数量级是多少？(2)这些关键参数之间是如何相互联系的，它们又是如何依赖于地质作用过程中变质环境的变化的？(3)这些参数、岩石微结构和大规模构造过程之间的联系是什么？岩石微结构形成的关键参数的相互作用和大小的研究仍处于起步阶段，但需要推进我们对地质系统中化学反应动力学作用的理解。拟议的研究将提高加拿大地球科学部门的竞争力，促进公众对矿物和岩石及其形成方式的内在兴趣。这项研究的直接应用将为构成加拿大经济重要部分的资源开采业提供联系。