Investigating the Partitioning of Vertical Strength within the India-Eurasia Lithosphere using Surface Observations: A Numerical Modeling Approach

使用地面观测研究印度-欧亚大陆岩石圈内垂直强度的划分：数值模拟方法

• 批准号: 1447100
• 负责人: Lucy Flesch
• 金额: $ 19万
• 依托单位: Purdue University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2018-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1447100&HistoricalAwards=false
• 关键词: Investigating; Partitioning; Vertical; Strength; within

The theory of plate tectonics was revolutionary in the field of geophysics and explained the motion of plates and locations of earthquakes and volcanoes. However, this theory breaks down at continental boundaries where earthquakes extend 1000?s of km and significant topography is created. The ongoing collision of the Indian and Eurasian plate provides a natural laboratory for studying such regions and the factors controlling deformation patterns in continental collisional zones. In the absence of direct sampling of the lithosphere with depth, numerical modeling can provide bounds on physically allowable lithospheric properties. Understanding the variation in strength within the continental lithosphere is fundamental to assessing the forces that generate earthquakes and build mountains. Results obtained within this proposal will have important implications relating to forces generating deformation of the Tibetan Plateau, stress transfer within the lithosphere, the depth to which surface observations sample lithospheric properties, partitioning of strength between upper crust, lower crust and lithospheric mantle, influence of the lower Indian plate beneath southern Tibetan, and flow the base of the lithosphere resulting from convection of the interior of the Earth.This project will perform 3-D geodynamic modeling solving Stokes flow to investigate the lateral and vertical strength variations within the Eurasian lithosphere. Geophysical observations will be used to construct a physically accurate model volume of the India-Eurasian collision zone, and numeric simulations will be performed to determine the effects of variations in lithospheric strength (both vertically and laterally) on predicted surface deformation. Comparisons between predicted surface velocities and the observed surface deformation field, constrained by GPS and quaternary fault slip data, will differentiate between physically viable models. This work will seek to: (1) Map out the allowable vertical strength contrasts within the Eurasian deforming lithosphere; (2) Isolate the depth sensitivity of surface observations within Eurasia; (3) Investigate the influence of variable lithospheric thickness and mantle flow on the observed surface deformation field.

板块构造理论在地球物理学领域是革命性的，它解释了板块的运动以及地震和火山的位置。 然而，这一理论在地震延伸数千公里并形成重要地形的大陆边界处就站不住脚了。 印度板块和欧亚板块的持续碰撞为研究这些区域以及控制大陆碰撞带变形模式的因素提供了一个天然的实验室。 在缺乏对岩石圈深度进行直接采样的情况下，数值模拟可以提供物理上允许的岩石圈特性的界限。 了解大陆岩石圈内强度的变化对于评估引发地震和建造山脉的力量至关重要。 该建议中获得的结果将对青藏高原变形的力、岩石圈内的应力传递、表面观测采样岩石圈特性的深度、上地壳、下地壳和岩石圈地幔之间的强度分配、岩石圈地幔的影响等方面产生重要影响。西藏南部下方的下印度板块，并由地球内部对流产生的岩石圈底部流动。该项目将进行 3D 地球动力学建模，求解斯托克斯流，以研究内部的横向和垂直强度变化欧亚岩石圈。 地球物理观测将用于构建印度-欧亚碰撞带的物理精确模型体积，并将进行数值模拟以确定岩石圈强度（垂直和横向）变化对预测地表变形的影响。 预测的地表速度与观测到的地表变形场（受 GPS 和第四纪断层滑移数据的约束）之间的比较将区分物理上可行的模型。 这项工作将寻求：（1）绘制出欧亚变形岩石圈内允许的垂直强度对比； (2) 隔离欧亚大陆内表面观测的深度敏感性； (3)研究变化的岩石圈厚度和地幔流对观测到的地表形变场的影响。