Extensional Deformation in Convergent Systems

了解为什么伸展应力发生，以及它是如何适应在会聚边缘仍然是了解收缩造山带的结构和力学演化的基础。 相对少量的张应力在会聚系统的长期构造演化中起着重要作用。这项研究主要是为了提高对伸展应力如何影响有限变形的演化、地形的发展和高原的形成的认识，特别是为了了解伸展变形如何影响在台湾、中安第斯山脉和西藏等造山系统中观察到的有限变形。这项研究将具体解决的参数，控制发生的伸展coeval与收缩，包括流变学（横向和深度），收敛速度，和初始板块的几何形状，包括板块运动的一致性的变化。了解这些过程对于更好地了解许多会聚边缘的构造至关重要。为此，采用了多方面的模拟方法，采用三维模拟与定量分析相结合的二维和三维有限元数值模拟和解析分析，在这项研究中的实验旨在解决的关键地质问题的拉伸和应变分配在几何复杂的设置在山区带的发展。一个大型的实验装置，可以容纳显着的面外变形将被使用。此外，数值建模将提供一个重要的对位，并交叉检查，强大的模拟建模方法。这项研究为早期职业调查人员提供了一个机会，了解地震活动变形的一种知之甚少的模式，同时为本科生、研究生培训和研究衍生的本科教学增强提供了研究机会。

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.