Collaborative Research: Quantifying the Dynamics of Asia Using GPS, Geologic and Shear-Wave Splitting Data, and Large-Scale Flow Models

合作研究：利用 GPS、地质和剪切波分裂数据以及大规模流动模型量化亚洲动态

• 批准号: 0609337
• 负责人: Lucy Flesch
• 金额: $ 25.59万
• 依托单位: Purdue University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0609337&HistoricalAwards=false
• 关键词: Collaborative; Research; Quantifying; Dynamics; Asia

This work aims at improving the understanding of the dynamics of continental deformation, one of the major unresolved -- and highly debated -- issues of the "plate tectonics era". Two end-member models dominate the scene. In the first one, the lithosphere is treated as a set of rigid "blocks" separated by finite zones of deformation, whose motions are controlled by forces applied at the edges of the blocks. In the second one, the lithosphere is treated as a viscous continuum and deformation is driven by both relative plate motions and buoyancy forces resulting from gravitational potential energy (GPE) gradients within the lithosphere.Asia is the largest zone of diffuse deformation on the surface of the Earth. As such, it is a natural laboratory to study how and why continents deform. Active deformation in Asia is fairly well documented geologically. This project incorporates a new geodetically-derived velocity and strain rate field that covers the entire continent. A key feature of this velocity field is the east- to southeastward motion of the entire eastern portion of central Asia from east of Baikal south to the Sunda block. This feature is not reproduced by block models where deformation is solely driven by the collision of a "rigid" Indian indenter into the Asian lithosphere. More comprehensive thin sheet modeling efforts that account for buoyancy forces and inter-plate coupling, are still not sufficient to explain this feature.This study is examining the driving forces responsible for continental deformation in Asia, with a particular emphasis on the eastward migration of the eastern margin observed in the GPS data by (1) combining the most recent GPS solutions and geologic data in Asia to determine a complete kinematic strain rate and velocity field over the entire continent, (2) computing the contribution of GPE variations (using lithospheric models) and of tractions at the base of the lithosphere (using mantle flow models derived from global tomography), (3) using the kinematic data and stress fields resulting from GPE gradients and basal traction to estimate boundary stresses and, eventually, determining a consistent set of forces that explain the geodetic observations. Additionally, shear-wave splitting observations in conjunction with the surface kinematic field are being used as an independent estimate, to directly solve for the direction of flow beneath East Asia in order to understand the origin of the eastward migration.Among the broader impacts of this work are support for an early career female researchers, support and training of a graduate student, and a female undergraduate.

这项工作旨在增进对大陆变形动力学的理解，这是“板块构造时代”尚未解决且备受争议的主要问题之一。两个最终成员模型占据了主导地位。在第一个模型中，岩石圈被视为一组由有限变形区域分隔的刚性“块”，其运动由施加在块边缘的力控制。在第二个模型中，岩石圈被视为粘性连续体，变形是由相对板块运动和岩石圈内重力势能 (GPE) 梯度产生的浮力驱动的。亚洲是地球表面最大的扩散变形区域。地球。因此，它是研究大陆如何以及为何变形的天然实验室。亚洲的活动变形在地质学上有相当详细的记录。该项目采用了覆盖整个大陆的新的大地测量速度和应变率场。该速度场的一个关键特征是整个中亚东部从贝加尔湖以东到巽他地块的东向东南运动。这一特征无法通过块体模型重现，块体模型的变形仅由“刚性”印度压头与亚洲岩石圈的碰撞驱动。考虑浮力和板间耦合的更全面的薄板建模工作仍然不足以解释这一特征。本研究正在研究亚洲大陆变形的驱动力，特别强调大陆的向东迁移通过 (1) 结合亚洲最新的 GPS 解决方案和地质数据来确定整个大陆的完整运动应变率和速度场，(2) 计算 GPE 变化的贡献（使用岩石圈模型） ）和的岩石圈底部的牵引力（使用从全球断层扫描得出的地幔流模型），（3）使用 GPE 梯度和基础牵引力产生的运动学数据和应力场来估计边界应力，并最终确定一组一致的力，解释大地测量观测结果。此外，剪切波分裂观测与表面运动场一起被用作独立估计，以直接求解东亚下方的流动方向，从而了解向东迁移的起源。工作包括对早期职业女性研究人员的支持、对研究生和女本科生的支持和培训。