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

合作提案：挖掘与爱达荷州-俄勒冈州陡峭大陆边缘岩石圈建筑的关系

• 批准号: 1251724
• 负责人: John Hole
• 金额: $ 5.59万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-08-01 至 2015-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1251724&HistoricalAwards=false
• 关键词: Collaborative; Proposal; Relation; Exhumation; Lithsopheric

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.

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以及驱动变形的底层地幔动力学之间的联系。 该区域位于爱达荷州西部的萨蒙河缝合带，是爱达荷州大部分地区的前寒武纪北美与俄勒冈州蓝山较年轻（显生宙）增生地体之间的边界。 爱达荷岩基仅形成于该边界的北美一侧。 碰撞后和正在进行的变形对该地区的不同部分产生不同的影响，代表了预先存在的地质结构和/或深层驱动力的差异。各个山脉抬升的时间、速率和量将与当前的地下几何形状相关（使用地震数据确定），以识别在区域尺度上抬升地形的地壳和地幔运动。 这项工作需要结合地震数据分析，提供详细的地下结构和热年代学，以确定岩石从深处隆起和折返的时间以及当前地形的发展。这项工作跨越三个主要研究领域和包括最终的项目综合：1）记录爱达荷州岩基亚特兰大叶的掘出路径，以确定它是否被较年轻的岩浆作用抬升； 2）评估沿着横切爱达荷岩基的跨查利斯断层带的潜在差异折返； 3) 蓝山挖掘的记录，以便将其历史与邻近的北美历史进行比较。 特别关注的是萨蒙河缝合带是否因后哥伦比亚河玄武岩延伸而重新激活。将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，将能够综合区域构造演化，并阐明继承的岩石圈结构和活动构造过程之间的关系。佛罗里达大学的两名研究生和两名本科生和弗吉尼亚理工大学直接受到这项工作的支持。 构造综合将涉及所有三个机构的研究生，其中一些机构由其他来源资助。