Tectonic Evolution of the Virgin-Beaverdam Extensional Breakaway Zone, Nevada, Arizona and Utah

岩石圈变形的物理学本质上是一个通过流变特性将应力和应变联系起来的连续问题。了解物理过程的进展包括实验室实验，直接测量地球材料的流变特性，以及岩石圈变形的良好自然实验。本项目旨在确定伸展环境下岩石圈对极端构造卸载的响应。一个潜在的研究区域位于维珍山脉的科罗拉多高原西缘，在那里，中中新世大规模的伸展构造活动沿着向西的正断层将原本与高原相邻的地壳碎片向西搬运了50-100 km。在这些被搬运的碎片之后，高原边缘的伸展“分离带”经历了至少5公里，甚至可能高达20公里的隆升。该提案将通过构造测绘和实验室流体包裹体研究来详细研究金丘区块，以确定内部破坏程度以及整个旋转区块的差异隆起和侵蚀程度。结果将直接关系到该地区确定均衡隆起在大陆伸展中的作用的适当性，也关系到岩石圈的伸展反应。

The physics of lithospheric deformation is primarily a continuum problem relating stress and strain through rheological properties. Progress towards understanding physical processes involves laboratory experiments that directly measure rheological properties in earth materials, and through well-posed natural experiments of lithospheric deformation. This project is aimed at determining the response of the lithosphere to extreme tectonic unloading in an extensional environment. A potential study area is located along the western margin of the Colorado Plateau in the Virgin Mountains, where large-scale mid-Miocene extensional tectonism along down-to-the-west normal faults has transported crustal fragments originally adjacent to the plateau 50-100 km to the west. In the wake of these transported fragments the extensional "breakaway zone" at the edge of the plateau experienced at least 5 and possibly as much as 20 km of uplift. This proposal will examine the Gold Butte block in detail, by structural mapping and laboratory fluid inclusion studies, to determine the degree of internal disruption and the amount of differential uplift and erosion across the rotated block. Results will bear directly on the appropriateness of this area determining the role of isostatic uplift in continental extension, and also on extensional response of the lithosphere generally.