Collaborative Research: Rivers, Faults, and Growing Mountains: Dynamic Feedback between Crustal Deformation, Rock Strength, and Erosion

大多数活动山脉的地形显示出变形和侵蚀之间的明显联系，其形式是与断层和剪切带紧密对齐的山谷网络。我们认为，这种关联是变形，岩石损伤和表面侵蚀之间的动态反馈的签名，这种反馈在造山带的演化中起着根本性的作用。通过这项研究计划，我们将测试我们的假设，即与构造驱动的地震相关的岩石破碎降低了地球上地壳的强度和粒度，在材料表面产生更容易被河流，山体滑坡和冰川侵蚀的区域。 侵蚀沿着这些弱化的断层带进行更迅速地比未变形的材料，因此，变形的历史被记录在地形结构。这些断层弱化带的三维方向在很大程度上取决于与地幔对流有关的大尺度板块构造。因此，如果我们的假设成立，那么我们将能够使用表面特征的方向（山谷和山脊）来描述地幔对流的长期历史在相对较高的分辨率。为了检验这一假设，我们提出了一个程序，结合先进的数值模拟和现场数据收集在新西兰南阿尔卑斯山，以评估两个可检验的预测：（1）地形与岩石强度之间应存在相关性，反映在体积粘聚力、裂缝密度、摩擦系数、抗拉强度和粒度等性质上;以及（2）基于我们目前对相关物理学的理解，三维变形和侵蚀的耦合模型应该产生地形图案，侵蚀和应变，这两者都与观测结果一致，并且与均匀岩石强度的情况有很大不同。我们预计，这项研究将提供重要的信息，科学家工作的相互依赖的表面和构造过程的尺度范围从地幔对流的个人流域。作为与该计划相关的推广活动的一部分，我们将制作和测试一个可通过网络访问的景观建模模块，该模块将允许K12和普通观众在简化的地貌/构造造山系统中进行景观开发的数值实验。 此外，该奖项被指定为OIIA/伊势全球风险基金奖，并由NSF的OIIA国际科学和工程部门共同资助。

The topography of most active mountain ranges shows a clear link between deformation and erosion in the form of valley networks that align closely with faults and shear zones. We propose that this association is the signature of dynamic feedback between deformation, rock damage, and surface erosion, and that this feedback plays a fundamental role in the evolution of orogens. With this research program, we will test our hypothesis that the rock crushing associated with tectonically-driven earthquakes reduces the strength and grain size of the upper crust of the Earth, producing zones at the surface of material that is more readily eroded by rivers, landslides and glaciers. Erosion along these weakened fault zones proceeds more rapidly than the non-deformed material, and consequently, the deformation history is recorded within the topographic fabric. The 3D orientation of these fault-weakened zones is largely determined by large scale plate tectonics related to mantle convection. Consequently, if our hypothesis is sustained, then we will be able to use the orientation of surface features (valleys and ridges) to describe the long term history of mantle convection at relatively high resolution.To test this hypothesis, we propose a program that combines advanced numerical modeling and field data collection in the Southern Alps of New Zealand to evaluate two testable predictions: (1) that there should exist a correlation between topography and rock strength, as reflected in properties such as bulk cohesion, fracture density, friction coefficient, tensile strength and grain size; and (2) that a coupled model of 3D deformation and erosion, based on our current understanding of the relevant physics, should produce patterns of topography, erosion, and strain that are both consistent with observations and substantially different from the case of uniform rock strength. We anticipate that this research will provide critical information for scientists working on the interdependence of surface and tectonic processes at scales ranging from those of mantle convection to those of individual drainage basins. As part of the outreach associated with this program, we will produce and test a Web-accessible landscape modeling module that will permit numerical experimentation by k12 and general audiences of landscape development in a simplified, coupled geomorphic/tectonic orogenic system.This project is supported by the Geomorphology and Land-use Dynamics program and the Tectonics program. In addition, this award is designated as an OIIA/ISE Global Venture Fund Award and is being co-funded by NSF's OIIA International Science and Engineering Section.