Collaborative Research: An integrated mantle to surface study of the causes and consequences of high topography in the Northern US Cordillera

最近的理论进展表明，发生在地幔深处的过程可能会对地球表面的地形产生重大影响。由于一个地区的地形历史可以影响气候和生物进化，因此了解地幔在塑造地貌中的作用对于理解地球作为一个系统是至关重要的。研究地幔和地表过程联系的一个主要障碍是，很少有地点可以很好地限制过去地幔和地表事件的时间历史。西北内陆，包括黄石热点的研究通道，提供了一个独特的机会来研究地幔动力学在山脉隆起和地貌演化中所起的作用。该项目侧重于俄勒冈州和爱达荷州的野外地点，旨在作为一项综合的地幔到地表的研究，量化该区域的侵蚀历史和该地区下的上地幔的结构。这项工作的结果将激励包含不同地幔过程和地形对一系列隆起模式的响应的通用模型。因此，我们的发现，虽然只针对我们的野外地点，但可能有助于揭示全球各地的地幔和地表相互作用。该项目将支持来自不同合作研究机构的三名研究生和三名初级研究人员。该项目还通过与俄勒冈州东部的两个组织建立合作伙伴关系，将学术科学家和研究学生与公共教育工作者和科学传播者联系起来。这两个组织分别是从事教育推广、环境行动和可再生能源项目的Wlowa Resources组织和该地区唯一的自然历史博物馆Wlowology。地幔动力学在推动隆起和景观演变中的作用是地球动力学和地貌学研究中一个关键但鲜为人知的方面。该项目将探索美国西北内陆崎岖多山的黄石羽流轨道以北的地幔驱动的造山隆起和地貌演变。没有其他大陆经历过与地幔热柱最近如此深刻的相互作用，这使该地区成为研究岩石圈尺度对地幔动力学响应的理想候选者。我们的研究是关于岩石圈和地貌对黄石羽流的响应的四个可检验的假说：(1)岩石圈剥离后的抬升和侵蚀，(2)滴状Rayleigh-Taylor对流引起的岩石圈丧失后的抬升和侵蚀，(3)浮力黄石羽流变平后的抬升和侵蚀，以及(4)断裂作用引起的侵蚀引起的排水重组。我们将建立在俄勒冈州东北部和爱达荷州中部先前地震、地质和景观研究的坚实基础上。这项有针对性的研究将通过地球动力学和地貌演化模拟，综合地质和地貌野外观测、低温热年代学和碎屑宇宙成因放射性核素得出的侵蚀速率和地幔层析成像，解决区域景观演化及其与成像地幔结构的关系。这项研究将产生将地幔动力学与隆起和地貌发展联系起来的模型，受我们研究区数据的限制，并适用于整个地球历史上的其他地点。这项工作通过提供与板块边界力无关的板内变形的可靠研究，将有助于完善板块构造理论。此外，我们预计这项研究将给出迄今为止最清晰的衡量地壳下地幔变形对景观演化重要性的衡量标准，这是从安第斯山脉到西藏研究的一个关键课题。

Recent theoretical advances suggest processes occurring deep within Earth's mantle can have significant impacts on topography at Earth's surface. As topographic history of a region can influence the climate and biologic evolution, understanding the role of the mantle in shaping the landscape is paramount to understanding the Earth as a system. A major barrier to the study of mantle and surface process linkages is that few locations exist where time histories of past mantle and surface events can be well constrained. The inland northwest, which includes the well-studied passage of the Yellowstone hotspot, offers a unique opportunity to examine the role mantle dynamics play in mountain uplift and landscape evolution. This project, which focuses on field sites in Oregon and Idaho, is designed as an integrated mantle to surface study that quantifies the regional erosion history and the structure of the upper mantle beneath this region. Results from this work will motivate generalized models incorporating different mantle processes and the topographic response to a range in uplift patterns. As a result, our findings, while specific to our field sites, may help shed light on mantle and surface interactions around the globe. The project will support three graduate students and three Primary Investigators from separate collaborating research institutions. The project also unites academic scientists and research students with public educators and science communicators through a partnership with two eastern Oregon organizations: Wallowa Resources, an organization that engages in educational outreach, environmental action, and renewable energy programs and Wallowology, the only natural history museum in this region.The role of mantle dynamics in driving uplift and landscape evolution is a critical and poorly understood facet of geodynamics and geomorphology research. This project will explore mantle driven epeiorogenic uplift and landscape evolution north of the Yellowstone plume track in the rugged and mountainous Inland Northwest of the United States. Nowhere else has a continent experienced such a recent and profound interaction with a mantle plume, making this area the ideal candidate for the examination of lithosphere-scale responses to mantle dynamics. Guiding our investigation are four testable hypotheses of lithospheric and landscape responses to the Yellowstone plume: (1) uplift and erosion following lithospheric loss through delamination, (2) uplift and erosion following lithospheric loss through drip-like Rayleigh-Taylor convection, (3) uplift and erosion following flattening of the buoyant Yellowstone plume, and (4) erosion driven by faulting induced drainage reorganization. We will build on a strong foundation of prior seismic, geologic and landscape studies across northeastern Oregon and central Idaho. This targeted study will resolve regional landscape evolution and its relation to imaged mantle structure via the integration of geologic and geomorphic field observations, low-temperature thermochronology, and detrital cosmogenic radionuclide derived erosion rates and mantle tomography through geodynamic and landscape evolution modeling. The research will generate models that relate mantle dynamics to uplift and landscape development, constrained by data from our study area and applicable to other locations throughout earth history. This work will help to refine plate-tectonics theory by providing a robust study of intraplate deformation not related to plate boundary forces. Furthermore, we anticipate this study will give the clearest-yet measure of the importance of sub-crustal mantle deformation on landscape evolution, a critical topic in studies from the Andes to Tibet.