Collaborative Proposal: Relation of Exhumation to Lithsopheric Architecture Along a Steep Continental Margin, Idaho-Oregon

该项目的目的是确定地形隆起、侵蚀和折返、预先存在的地质边界和驱动变形的下伏地幔动力学之间的联系。 野外区域是爱达荷州西部的鲑鱼河缝合带，该缝合带是爱达荷州大部分地区下面的前寒武纪北美与俄勒冈州蓝山的年轻（中生代）增生岩之间的边界。 爱达荷州岩基完全形成于这一边界的北美一侧。 碰撞后和正在发生的变形对该区域不同部分的影响不同，表明先前存在的地质结构和（或）深部驱动力存在差异。各种山脉隆起的时间、速率和数量将与当前的地下几何形状有关--利用地震数据确定--以确定地球的运动？在区域尺度上抬升地形的地壳和地幔。 这项工作需要结合地震数据分析，以提供详细的地下结构，以及热年代学，以确定从深度和当前地形的发展上升和岩石折返的时间。这项工作跨越三个主要研究领域，包括最终项目综合：1）记录爱达荷州岩基亚特兰大裂片的折返路径，以确定它是否是由较年轻的岩浆活动抬升的; 2）沿横贯爱达荷州岩基的trans-Challis断层带沿着潜在差异剥露的评价; 3）蓝山剥露的记录，以便将其历史与邻近的北美进行比较。 一个特别的焦点是鲑鱼河缝合带是否重新激活后哥伦比亚河玄武岩延伸。热年代学和地震结果与最近的地质学，地质年代学和地球化学研究相结合，将允许合成的区域构造演化，可以阐明继承的岩石圈结构和活动构造processes.Two研究生和两个本科生在佛罗里达大学和弗吉尼亚理工大学的关系直接支持这项工作。 构造综合将涉及所有三个机构的研究生，其中一些人是由其他来源资助的。

The aim of this project is to determine the link between topographic uplift, erosion and exhumation, pre-existing geologic boundaries, and the underlying mantle dynamics that drive deformation. The field area is the Salmon River suture zone of western Idaho, which is the boundary between Precambrian North America underlying most of Idaho and younger (Phanerozoic) accreted terranes of the Blue Mountains in Oregon. The Idaho batholith formed exclusively on the North American side of this boundary. Post-collision and ongoing deformation affect different parts of the region differently, representing differences in pre-existing geologic structure and/or in deep driving forces. The timing, rates, and amounts of uplift of the various mountain ranges will be related to the current subsurface geometry -- determined using seismic data -- to identify motions in the Earth?s crust and mantle that elevated topography on regional scales. The work entails a combination of seismic data analyses, to provide a detailed sub-surface architecture, and thermochronology, to determing the timing of uplift and exhumation of rocks from depth and the development of the current topography.The work spans three main study areas and includes a final project synthesis: 1) Documentation of the exhumation path of the Atlanta lobe of the Idaho batholith to determine if it was uplifted by younger magmatism; 2) Evaluation of potential differential exhumation along the trans-Challis fault zone that cross-cuts the Idaho batholith; and 3) Documentation of exhumation in the Blue Mountains, in order to compare its history to that of adjacent North America. A particular focus is whether the Salmon River suture zone was reactivated by post-Columbia River Basalt extension. The combination of the thermochronology and seismic results with recent geology, geochronology, and geochemistry studies will allow synthesis of a regional tectonic evolution and can illuminate the relationship between inherited lithospheric structures and active tectonic processes.Two graduate and two undergraduate students at the University of Florida and Virginia Tech are directly supported by this work. Tectonic synthesis will involve graduate students at all three institutions, several of whom are funded by other sources.