Collaborative Research: The Lake Superior Basin: Natural Geomorphic Experiment, Deepwater-Terminating Ice Stream, and Isostatically Adjusting Rift

合作研究：苏必利尔湖盆地：自然地貌实验、深水终止冰流和均衡调整裂谷

• 批准号: 2218460
• 负责人: Jerry Mitrovica
• 金额: $ 21.72万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-15 至 2027-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2218460&HistoricalAwards=false
• 关键词: Collaborative; Research; Lake; Superior; Basin

Glaciers, lakes, rivers, and the solid Earth interact to reshape the surface environment. This applies to the Lake Superior Basin, a basin that formed as a rift in Earth's crust 1.1 billion years ago and since has hosted mountains, lakes, glaciers, rivers, and human inhabitants. Past and present lake-level change is responding to ancient ice-sheet retreat, whose unweighting of Earth's surface causes our planet's crust to bend and underlying mantle to flow. This project takes a multidisplinary approach to better understand the shaping of this continental landscape. The research team is reconstructing how the geological past of the Lake Superior basin impacts ongoing uplift and tilting of the land surface as well as surface processes including river erosion. Lake-level fall incites rivers to slice downwards through sediment and rock, while lake-level rise drowns the river mouths, causing deposition of gravel and sand. Mapping the three-dimensional patterns of the rivers encompassing the Lake Superior Basin, as they cut through materials ranging from soft mud to hard rock, is critical for understanding erosional processes. Additionally, dating landforms associated with past water-terminating glaciers and simulating their dynamics using computer models will improve scientists' ability to predict the fate of Earth’s existing ice sheets. Indigenous Ojibwe partners will consult in the research and share knowledge of both land and lake. Through a partnership with the Superior Hiking Trail Association, the project team will enhance outdoor recreation by providing public scientific knowledge of the region and its natural history. Finally, the research team is self-examining its approaches and practices to learn how to better include and support upcoming generations of Earth scientists.Through the nexus of the Lake Superior basin, this research is answering fundamental questions about river incision, (de)glacial landscape and lake-scape evolution, water-terminating glacier instabilities, and glacial isostatic adjustment. Lake Superior provides a uniquely suited testbed to advance each of these knowledge areas and to understand their feedbacks. Synchronous base-level fall on Lake Superior triggered river incision and knickpoint propagation across myriad lithologies, providing replicate natural experiments in erosional mechanics. The project team is applying traditional glacial geological approaches together with state-of-the-art topographic analyses to map lake-level evolution and the extent of glacial and fluvial process domains. Paleolake shorelines and spillways were modified by, and record, glacial isostatic adjustment, which can be further constrained via detailed seismic imaging of three-dimensional solid-Earth structure and extensive modern global navigation satellite system data. These data are being used to probe deeply into the mechanisms and feedbacks surrounding the marine ice sheet instability, critical for understanding the response and sensitivity of marine-terminating outlet glaciers and ice sheets. The research team is partnering with local nonprofit and government organizations to share the narrative of the Lake Superior region, integrate Indigenous knowledge, and build an inclusive field-research program whose goal is to invite a diversifying next generation into the geosciencesThis award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

冰川、湖泊、河流和固体地球相互作用，重塑了地表环境。苏必利尔湖盆地是 11 亿年前地壳裂谷形成的盆地，自此以后，这里就孕育着山脉、湖泊、冰川和河流。以及人类居民。过去和现在的湖泊水位变化是对古代冰盖退缩的反应，其导致地球表面的失重导致地壳弯曲和地幔流动。研究小组正在采用多学科方法来更好地了解苏必利尔湖盆地的地质历史如何影响陆地表面的持续抬升和倾斜以及包括河流侵蚀在内的地表过程。河流向下切割沉积物和岩石，而湖水上升淹没了河口，导致砾石和沙子沉积，绘制了苏必利尔湖盆地河流的三维模式，因为它们切割了软质物质。此外，对与过去的断水冰川相关的地貌进行年代测定并使用计算机模型模拟其动态将提高科学家预测地球现有冰盖命运的能力。通过与高级远足步道协会合作，项目团队将通过提供有关该地区及其自然历史的公共科学知识来加强户外休闲活动。检查其方法和实践旨在学习如何更好地包容和支持下一代地球科学家。通过苏必利尔湖盆地的联系，这项研究正在回答有关河流切割、冰川（去）冰川景观和湖泊景观演化、水-景观的基本问题。终止冰川不稳定性和冰川均衡调整提供了一个独特的测试平台来推进这些知识领域并了解其反馈。跨越无数岩性，提供侵蚀力学的复制自然实验，该项目团队正在应用传统的冰川地质方法和最先进的地形分析来绘制湖泊水位演化以及冰川和河流过程域的范围。溢洪道通过冰川均衡调整进行了修改和记录，可以通过三维固体地球结构的详细地震成像和广泛的现代全球导航卫星系统数据进一步限制这些数据正在使用。深入探讨海洋冰盖不稳定的机制和反馈，这对于了解海洋终止出口冰川和冰盖的响应和敏感性至关重要。该研究团队正在与当地非营利组织和政府组织合作，分享有关该湖的叙述。优越的地区，整合土著知识，并建立一个包容性的实地研究计划，其目标是邀请多元化的下一代进入地球科学领域。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查进行评估，被认为值得支持标准。