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: 2218464
• 负责人: Andrew Breckenridge
• 金额: $ 9.31万
• 依托单位: University of Wisconsin-Superior
• 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=2218464&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。苏必利尔湖上级盆地就是这样一个盆地，它是在11亿年前地壳的一个裂缝中形成的，从那时起，这里就有了山脉、湖泊、冰川、河流和人类居民。过去和现在的湖平面变化是对古代冰盖退缩的反应，冰盖退缩使地球表面失重，导致地球地壳弯曲，下面的地幔流动。该项目采用多学科方法，以更好地了解这一大陆景观的形成。研究小组正在重建苏必利尔湖上级盆地的地质历史如何影响陆地表面的持续隆起和倾斜以及包括河流侵蚀在内的表面过程。湖平面下降促使河流向下切割沉积物和岩石，而湖平面上升淹没河口，导致砾石和沙子沉积。绘制环绕苏必利尔湖上级盆地的河流的三维图案，因为它们穿过从软泥到硬岩的材料，对于理解侵蚀过程至关重要。此外，确定与过去水终止冰川相关的地貌的年代，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。土著Ojibwe合作伙伴将在研究中提供咨询，并分享土地和湖泊的知识。通过与上级徒步旅行径协会的合作，项目小组将通过提供该地区及其自然历史的公众科学知识来加强户外娱乐活动。最后，研究小组正在自我检查其方法和实践，以了解如何更好地包括和支持未来几代地球科学家。通过苏必利尔湖上级盆地的联系，这项研究正在回答有关河流切割，（去）冰川景观和湖泊景观演变，水终止冰川不稳定性和冰川均衡调整的基本问题。Lake上级提供了一个独特的适合的测试平台，以推进这些知识领域的每一个，并了解他们的反馈。上级湖的同步基准面下降引发了河流的切割和跨越无数岩性的断点传播，提供了复制侵蚀力学的自然实验。项目小组正在采用传统的冰川地质学方法和最先进的地形分析，绘制湖泊演变图以及冰川和河流过程域的范围。古湖岸线和溢洪道因冰川均衡调整而改变，并记录了这种调整，而这种调整可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加以限制。这些数据被用来深入探讨海洋冰盖不稳定性的机制和反馈，这对于理解海洋终端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的非营利组织和政府组织合作，分享苏必利尔湖上级地区的故事，整合土著知识，并建立一个包容性的实地研究计划，其目标是邀请多样化的下一代进入地球科学。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。