Understanding Past Environments and Glacial Processes Through an Analysis of a Newly Discovered Glacial Lake

通过分析新发现的冰川湖了解过去的环境和冰川过程

• 批准号: 1759528
• 负责人: Randall Schaetzl
• 金额: $ 34.9万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-05-01 至 2024-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1759528&HistoricalAwards=false
• 关键词: Understanding; Past; Environments; Glacial; Processes

This project will examine the paleoenvironmental and geological history of a newly discovered, ancient glacial lake. Preliminary data suggest that Glacial Lake Roscommon (GLR) came into existence circa 24-23,000 years ago and persisted for over 7000 years, in an area previously thought to be ice-covered until nearly 16,000 years ago. Research on this lake will refine the understanding of Midwestern glacial dynamics, thereby improving modeling of ice-sheet thickness for North America. A better understanding of glacial retreat in this area, and of past glacial processes in general, will enhance the ability to locate important natural resources derived from glacial landforms such as aggregate, as well as sand and clay, and will help model aquifer continuity and hence, improve present-day groundwater management strategies. Several remnant lakes from GLR still exist in the study area and may have existed continuously since deglaciation. Sediment cores from these lakes will be dated and analyzed for fossil pollen, plant macrofossils, and snail shells, yielding important insights into the immediate postglacial climate of the region, and providing new insights into the earliest forms of plant colonization of cold, recently deglaciated landscapes. The project provides many opportunities for graduate and undergraduate student training and mentoring, both in the field and in the laboratory. Results from the research will be broadly disseminated in academic and non-academic outlets and the work will be the focus of a regional field conference.The recent scientific documentation of Glacial Lake Roscommon (GLR), offers a rare opportunity to generate new knowledge and contribute to the rewriting the glacial history of the upper Midwest. The lake is unique, having developed in the upper Great Lakes region at a time when other Midwestern glaciers were near their maximum extent. This area was thought to have been ice-covered until about 16,000 years ago, implying that the sediments from the lake and its remnants may contain the longest record of pollen and other fossils in the upper Midwest. Such a long record is exceedingly rare. The potential of this record will be examined by coring several remnant lakes, dating the lowermost plant matter in each core using radiocarbon technology, and examining those data to determine the oldest core. Data on pollen, macrofossils, and ostracodes from these cores will then be examined to provide an unprecedented view into the environment at a time when ice dominated the landscape, and postglacial plant colonization was just beginning. A second focus of the research is the determination of the geological record of GLR and the retreating ice margin within it is. This part of the project involves dating of beach and related sediments, using luminescence technologies. Such data will help constrain the evolution of the lake and its bounding ice margins, and thus, add key data for ice-sheet models. Because the lake had at least three different outlets, constraining the opening and abandonment of these outlets will help determine the ice retreat scenarios for bounding landscapes. Early data suggest that ice on nearby landscapes had also retreated, or had begun retreating, far earlier than is currently thought.This 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.

该项目将研究一个新发现的古冰川湖的古环境和地质历史。 初步数据表明，罗斯康芒冰川湖（GLR）大约在24000年至23000年前形成，并持续了7000多年，在一个以前被认为是冰层覆盖的地区，直到近16,000年前。 对这个湖的研究将改善对中西部冰川动力学的理解，从而改善对北美冰盖厚度的建模。 更好地了解这一地区的冰川退缩和过去的冰川过程，将提高定位来自冰川地貌的重要自然资源的能力，如骨料，以及沙子和粘土，并将有助于模拟含水层的连续性，从而改善当今的地下水管理战略。 研究区仍有几个大湖区残留湖泊存在，可能是冰消期以来连续存在的。 这些湖泊的沉积物岩芯将被测年，并分析化石花粉，植物宏化石和蜗牛壳，产生重要的见解直接冰后期气候的地区，并提供新的见解最早形式的植物殖民化的寒冷，最近冰川消退的景观。 该项目为研究生和本科生的培训和指导提供了许多机会，无论是在现场还是在实验室。 研究结果将在学术和非学术渠道广泛传播，这项工作将成为区域实地会议的重点。最近的罗斯康芒冰川湖（GLR）的科学文献，提供了一个难得的机会，以产生新的知识，并有助于改写上中西部的冰川历史。 这个湖是独一无二的，在其他中西部冰川接近最大范围的时候，在五大湖上游地区发展起来。 这一地区被认为在大约16,000年前一直被冰层覆盖，这意味着该湖及其遗迹的沉积物可能含有中西部上游最长的花粉和其他化石记录。 如此长的记录是极其罕见的。 这一记录的潜力将通过对几个残留湖泊取芯，使用放射性碳技术测定每个岩心中最低的植物物质的年代，并检查这些数据以确定最古老的岩心来进行检查。 然后，将对这些岩心中的花粉、宏体化石和介形虫的数据进行检查，以提供一个前所未有的视角，了解当时冰占主导地位的环境，冰后期植物殖民才刚刚开始。 研究的第二个重点是确定GLR的地质记录和其中的退缩冰缘。 项目的这一部分涉及利用发光技术测定海滩和相关沉积物的年代。 这些数据将有助于限制湖泊及其边界冰缘的演变，从而为冰盖模型增加关键数据。 由于该湖至少有三个不同的出口，限制这些出口的开放和放弃将有助于确定边界景观的冰撤退方案。 早期的数据表明，附近景观上的冰也退缩了，或已经开始退缩，远远早于目前认为的。这个奖项反映了NSF的法定使命，并已被认为是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的支持。

项目成果

Interpreting Basal Sediments and Plant Fossils in Kettle Lakes: Insights from Silver Lake, Michigan, USA

解释水壶湖的基底沉积物和植物化石：来自美国密歇根州银湖的见解

• 发表时间: 2020
• 期刊: Canadian journal of earth sciences
• 影响因子: 1.4
• 作者: Yansa, C.;Fulton III, A.;Schaetzl, R.J.;Kettle, J.;Arbogast, A.F.
• 通讯作者: Arbogast, A.F.