Extensional Deformation in Convergent Systems

理解拉应力发生的原因以及拉应力如何在会聚边缘被调节，对于理解收缩造山带的结构和力学演化至关重要。相对少量的拉应力对会聚体系的长期构造演化具有重要作用。本研究的重点是提高对伸展应力如何影响有限变形的演化、地形的发展和高原形成的理解，特别是对伸展变形如何影响在台湾、安第斯山脉中部和西藏等造山带观测到的有限变形的理解。本研究将专门研究控制伸展与收缩同时发生的参数，包括流变学（横向和深度）、收敛速率和初始板块几何形状（包括板块运动倾角）的变化。了解这些过程是更好地理解许多汇聚边缘构造的基础。为此目的，正在使用多方面的建模方法，将三维模拟建模与定量分析结合起来，结合二维和三维有限元数值建模和分析分析。本研究的实验旨在解决山带发育过程中几何复杂背景下的伸展和应变分配等关键地质问题。将使用一种能容纳明显面外变形的大型实验装置。此外，数值模拟将提供一个重要的对应物，并交叉检查，稳健的模拟建模方法。这项研究为早期的研究人员提供了一个了解地震活动变形模式的机会，同时也为本科生、研究生培训提供了研究机会，并为本科生教学提供了研究成果。

Understanding why extensional stress occurs and how it is accommodated at convergent margins remains fundamental to understanding the structural and mechanical evolution of contractional orogens. A relatively small amount of extensional stress can play an important role in the long-term structural evolution of convergent systems. This study is broadly focused on improving the understanding of how extensional stress can affect the evolution of the finite deformation and the development of topography and the formation of plateaus and, specifically, towards understanding how extensional deformation has influenced the finite deformation observed in orogenic systems such as Taiwan, the Central Andes, and Tibet. This study will specifically address the parameters that control the occurrence of extension coeval with contraction, including variations in rheology (laterally and with depth), convergence rate, and initial plate geometries, including plate motion obliquity. Understanding these processes is fundamental to a better understanding of the tectonics of many convergent margins. To this end, a multifaceted modeling approach is being used that employs three-dimensional analog modeling with quantitative analysis in conjunction with two and three-dimensional finite element numerical modeling and analytical analysis.The experiments in this study are designed to address key geological issues of extension and strain partitioning in geometric complex settings during the development of mountain-belts. A large experimental apparatus that can accommodate significant out-of-plane deformation will be used. Additionally, numerical modeling will provide an essential counterpoint to, and a cross-check for, the robust analog modeling method. The study provides an opportunity for early career investigators to learn about a poorly understood mode of seismically active deformation while providing research opportunities for undergraduate students, graduate student training, and research derived enhancements to undergraduate teaching.