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

点击翻译按钮获取中文摘要

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.