Integrated field and numerical investigations on multiscale structures in Earth's lithosphere

地球岩石圈多尺度结构的综合实地和数值研究

• 批准号: RGPIN-2014-04885
• 负责人: Jiang, Dazhi
• 金额: $ 2.19万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633768
• 关键词: Integrated; field; numerical; investigations; multiscale

We propose to develop robust numerical models for the deformation of the continental lithosphere and to test these models by field-oriented studies of natural deformation zones. Our goal is to establish a rigorous framework for studying small-scale structures so that they can be used to infer large-scale tectonics and the rheology of the continental lithosphere.The Earth is unique among the terrestrial planets in the solar system in that it has plate tectonics which causes lithospheric plates to deform in plate boundary and interior regions. Understanding the physics of this deformation is of paramount significance both scientifically, for understanding the evolution of Earth and other planets, and practically for the welfare of human beings who live on the lithosphere, mitigate natural hazards, and derive energy, mineral, and other resources from it. Despite its close relationship to humanity and in contrast to our level of understanding of the oceanic lithosphere, continental deformation over long terms (millions of years) and across vast spatial scales (comparable to the size of a continent like the North America) remains poorly understood. This is because the continental lithosphere is far more heterogeneous mechanically than the oceanic lithosphere on a wide range of observation scales. After many decades of research, we still lack an effective means to tackle the deformation of such a heterogeneous body on multiscales. This research will build on the applicant’s recent progress and combine direct geological investigations on deformation structures, which are “signatures” of past lithospheric deformation, with a novel numerical modeling approach based on continuum micromechanics, which addresses the multiscale deformation of heterogeneous materials. How to tackle effectively the deformation of a rheologically heterogeneous continental lithosphere and to model the accompanying development of multiscale structures have been most fundamental issues in the field of structural geology and tectonics, and bottle necks to its advances. For over 4 decades, the structural and tectonics community has resorted to single-scale models (mostly homogeneous and of a kinematic nature), although they have long been recognized as highly unrealistic. The key to the problem is to find a rigorous means to address the great variability in the flow field in a heterogeneous material like the continental lithosphere. Recently, the applicant has succeeded in developing a MultiOrder Power Law Approach (MOPLA) based on micromechanics for non-Newtonian viscous materials (believed to be the best representation of Earth's lithosphere) which, for the first time, places fabric modeling on rigorous mechanical grounds. This proposal requests funds 1) to develop MOPLA into a more robust model, a self-consistent one that incorporates the significant effect of the evolving rheology due to fabric buildup in the process of deformation, and 2) to test the model predictions by field studies in well-defined natural deformation zones. The outcome of this research is expected to be a landmark achievement in structural geology and tectonics. The research objectives align with my long-term research goal to establish an integrated theoretical, numerical, and field methodology for studying small structures. The research activities will include theoretical formulation and implementation of numerical models and field and laboratory work. These activities will involve many graduate students and other research associates. Thus the research provides a platform for teaching advanced fieldwork, laboratory, and computational skills to undergraduate, graduate students, and junior scientists, combining scientific investigation with the training of new scientists.

我们建议开发可靠的数值模型，以使连续岩石圈的变形，并通过自然变形区的现场研究测试这些模型。我们的目标是建立一个严格的框架来研究小规模的结构，以便它们可以用于推断大规模的构造和连续岩石圈的流变学。地球在太阳系中的陆地行星中是独一无二的，因为它具有板块构造的，它具有导致岩石圈在板块边界和互动区域中变形的岩石圈。理解这种变形的物理学在科学上是至关重要的，既是理解地球及其他行星的演变，也是对生活在岩石圈上，减轻自然危害的人类福利的实际意义，并从中获得了能量，矿物质和其他资源。尽管它与人类的关系紧密，并且与我们对海洋岩石圈的理解水平相反，但长期（数百万年）和巨大的空间尺度（与像北美这样的连续的大小相当）的持续变形仍然很众所周知。这是因为在各种观察量表上，连续的岩石圈在机械上比海洋岩石圈更为异质。经过数十年的研究，我们仍然缺乏一种有效的手段来应对多层群体上这种异质体的变形。这项研究将基于申请人的最新进展，并将对变形结构的直接地质研究结合在一起，这是过去岩石圈变形的“签名”，其基于连续的微力学的新型数值建模方法，该方法涉及异质材料的多构型变形。如何有效地解决流变学上异质连续岩石圈的变形以及对多尺度结构的参与发展进行建模一直是结构地质和构造学领域的最基本问题，以及瓶颈的进步。在40多年来，结构性和构造界群落一直诉诸单尺度模型（大多数是均匀的，具有运动性质），尽管它们长期以来一直被认为是高度不现实的。问题的关键是找到一种严格的均值，以解决连续岩石圈等异质材料中流场的巨大变化。最近，该适用的成功开发了基于非牛顿粘性材料的微力学（认为是地球岩石圈的最佳代表）的多器电力法方法（MOPLA），这首先将织物建模在严格的机械基础上。该提案要求资金1）将MOPLA开发为一个更强大的模型，这是一种自洽的模型，该模型在变形过程中纳入了由于织物堆积而不断发展的流变学的显着效果，而2）通过在定义明确的自然变形区中通过现场研究来测试模型预测。这项研究的结果预计将是结构地质和构造学中的具有里程碑意义的成就。研究目标与我的长期研究目标保持一致，以建立用于研究小结构的综合理论，数值和现场方法。研究活动将包括理论公式以及数值模型以及现场和实验室工作的实施。这些活动将涉及许多研究生和其他研究伙伴。这项研究为本科，研究生和初级科学家提供了教授高级现场工作，实验室和计算技能的平台，并将科学研究与新科学家的培训相结合。