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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

基本信息

批准号：
2218463
负责人：
Marianne Haseloff
金额：
$ 73.77万
依托单位：
University of Wisconsin-Madison
依托单位国家：
美国
项目类别：
Continuing 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=2218463&HistoricalAwards=false
关键词：
Collaborative Research Lake Superior basin

项目摘要

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，重塑地表环境。这适用于苏必利尔湖盆地，这是一个11亿年前作为地壳裂隙形成的盆地，自那以来拥有山脉、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老的冰盖退缩的响应，冰盖的减重导致我们的地壳弯曲，地下地幔流动。这个项目采取了多学科的方法，以更好地理解这一大陆景观的形成。研究小组正在重建苏必利尔湖盆地的地质历史如何影响陆面的持续抬升和倾斜，以及包括河流侵蚀在内的地表过程。湖面的下降刺激河流向下切割沉积物和岩石，而湖面的上升淹没了河口，导致砾石和沙子的沉积。绘制围绕苏必利尔湖盆地的河流的三维图形，因为它们切割了从软泥土到硬岩石的各种物质，对于了解侵蚀过程至关重要。此外，测定与过去终止水的冰川有关的地貌，并使用计算机模型模拟它们的动态，将提高科学家预测地球上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。通过与高级徒步旅行步道协会的合作，该项目团队将通过提供该地区及其自然历史的公共科学知识来加强户外娱乐。最后，研究小组正在自我检查其方法和实践，以了解如何更好地纳入和支持未来几代地球科学家。通过苏必利尔湖盆地的联系，这项研究正在回答关于河流切割、冰川景观和湖泊景观演变、终止水的冰川不稳定以及冰川均衡调整等基本问题。苏必利尔湖提供了一个独特的适合的试验台，以推进这些知识领域的每一个并了解它们的反馈。苏必利尔湖的同步基准面下降触发了河流切割和节点点在各种岩性中的传播，提供了侵蚀力学中重复的自然实验。项目组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变以及冰川和河流过程域的范围。古湖岸线和溢洪道被冰川均衡调整所修正和记录，这可以通过详细的三维固体地球结构的地震成像和广泛的现代全球导航卫星系统数据来进一步限制。这些数据正被用来深入探讨围绕海洋冰盖不稳定的机制和反馈，这对于理解海洋末端出口冰川和冰盖的反应和敏感性至关重要。研究团队正与当地非营利组织和政府组织合作，分享苏必利尔湖地区的故事，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优势和更广泛的影响审查标准进行评估，被认为值得支持。