Geodynamics of continents and convergent plate margins

地质特征，如山脉、火山和经济矿藏，是地球表面下发生的过程的结果，直接取决于成分、温度和应力。有些过程发生在几分钟内(例如地震)，而另一些过程则需要数百万年(例如造山)。我的研究计划针对的是发生在很长时间尺度上的过程，重点是北美西部和南美。这两个地区的特点都是由于海洋构造板块下降到大陆以下而形成的大山带，这一过程被称为俯冲。然而，大陆变形和造山的细节仍然知之甚少。在一些地方，由于大洋板块在大陆以下水平以下移动(称为平板式俯冲)，可能导致了强化的变形。除了区域变形外，山带还受到地壳和刚性地幔内局部重力驱动的变形的影响。对于北美和南美洲，形变发生在海岸500-1000公里范围内。东部的界限对应于古老大陆的区域，被认为太冷太强而不能变形。我的计划旨在了解俯冲和造山的动力学。在今后五年中，我的小组将研究三个主要专题：a)评估板块俯冲及其对大陆变形的影响；b)分析山地带内的局部尺度动力学，包括重力变薄和软壳的横向流动；c)研究山地带的东部边界。为什么毗邻的大陆没有变形，边界的几何形状是否为山脉带的形成提供了线索？这项工作将与8名研究生和至少5名本科生一起进行。我们将使用计算机模型来研究数百万年来的形变动力学。这些模型为地表地质记录(例如地形的变化)和地球物理测量(例如地震速度的空间变化)提供了定量预测。通过与北美西部和南美洲现有观测结果的比较，我们可以确定模型行为是否合理。相反，这些模型增强了对观测的解释，并指出了需要新数据的区域。这项研究提供了对造山和地下过程如何在地表地质中记录的洞察。我们的工作将集中在北美西部和南美洲，但我们的目标是确定与全球俯冲带相关的基本过程。我们的模型还提供了有关地球温度和应力条件的信息。因此，这项工作对于了解短期形变的条件(即地震和地震危险评估)以及地热能评估、碳氢化合物潜力和矿物/钻石勘探具有重要意义。

Geological features, such as mountains, volcanoes and economic mineral deposits, are the result of processes occurring below the Earth's surface and depend directly on the composition, temperature, and stress. Some processes occur within minutes (e.g., earthquakes) while others take millions of years (e.g., mountain-building). My research program addresses processes that occur over long timescales, focusing on western North and South America. Both areas are characterized by large mountain belts that formed as oceanic tectonic plates descended below the continent, a process called subduction. However, the details of continental deformation and mountain-building remain poorly understood. In some places, enhanced deformation may have resulted as the oceanic plate travelled subhorizontally below the continent (termed flat-slab subduction). In addition to regional deformation, the mountain belt is affected by local gravitationally-driven deformation within the crust and rigid mantle. For North and South America, deformation occurs within 500-1000 km of the coast. The eastern limit corresponds to areas of older continent, believed to be too cold and strong to deform.My program aims to understand the dynamics of subduction and mountain-building. Over the next five years, my group will study three main topics:a) an assessment of flat-slab subduction and its effect on continent deformationb) an analysis of local-scale dynamics within mountain belts, including gravitational thinning and lateral flow of weak crustc) an examination of the east boundary of the mountain belt. Why does the adjacent continent not deform, and does the geometry of the boundary provide clues to mountain belt formation?This work will be carried out with 8 graduate students and at least 5 undergraduates. We will use computer models to study the dynamics of deformation over millions of years. The models provide quantitative predictions for the surface geological record (e.g., changes in topography) and geophysical measurements (e.g., spatial variations in seismic velocity). Comparisons with existing observations in western North and South America allow us to determine whether the model behaviours are reasonable. Conversely, the models enhance the interpretation of observations and point to areas where new data is needed.This research provides insight into mountain-building and how subsurface processes are recorded in surface geology. Our work will focus on western North and South America, but we aim to identify fundamental processes relevant to subduction zones globally. Our models also provide information about the temperature and stress conditions in the Earth. Thus, this work is relevant to understanding the conditions for short-term deformation (i.e., earthquakes and seismic hazard assessment), as well as geothermal energy evaluation, hydrocarbon potential and mineral/diamond exploration.