Development of a glacial abrasion rule for landscape-evolution models

景观演化模型冰川磨损规则的发展

• 批准号: 2017185
• 负责人: Lucas Zoet
• 金额: $ 20.94万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2017185&HistoricalAwards=false
• 关键词: Development; glacial; abrasion; rule; landscape

Glacial landscapes are sculpted by the ice that slides above them. The constant flow of ice wears away at the underlying bedrock, eroding it through time. The rates and patterns of this wear stem in part from a process called abrasion, which results from sediment entrained in basal ice being pressed into the underlying rock and drug along by the glacier. A number of theories have been proposed to estimate abrasion rates, which depend on a multitude of parameters. In order to accurately model the evolution of glacial landscapes, a mathematical “abrasion law” is needed that accurately captures the physics relevant to abrasion. The form of the abrasion law is difficult to determine beneath real glaciers because their beds are often inaccessible and the controlling factors are difficult to measure in the field. Further compounding these difficulties is the fact that abrasion rates are miniscule and therefore require decades or centuries to pass before the eroded volume is measurable. The goal of this project is to develop a mathematical relationship that describes the physics of glacial abrasion using a novel set of laboratory instruments, so that it can be implemented in numerical landscape evolution models. In the laboratory, conditions can be controlled and measured with the precision needed to accurately determine the abrasion law. The project will support a graduate and an undergraduate student from UW-Madison and provide training for underrepresented students from the College of Menominee Nation.A large-diameter ring shear device and a direct shear device at UW-Madison will be used to slide debris-laden ice at the pressure melting point over rock beds that vary in shape and composition. The striations produced by abrasion will be analyzed using a white light interferometer capable of measuring the volume of eroded material down to 10-18 cubic meters. With the ability to measure these miniscule volumes, the sliding experiments can be conducted in relatively short timeframes (less than one month each) and still generate sufficient abraded volume to determine the abrasion law. Using these instruments, an abrasion law will be developed that relates the rate of erosion to independent variables, such as sliding speed, basal melting, bed shape, debris hardness, and debris concentration.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.

冰川景观是由滑动它们上方的冰雕刻的。冰的恒定流在下面的基岩上磨损，随着时间的流逝而侵蚀它。这种磨损的速率和模式部分是由于一个称为磨蚀的过程，这是由于冰川沿着基本冰中的沉积物所带来的沉积物所致。已经提出了许多理论来估计磨损率，这取决于多种参数。为了准确模拟冰川景观的演变，需要一种数学“磨损定律”，以准确捕获与磨损相关的物理学。磨损定律的形式很难在实际冰川下确定，因为它们的床通常无法接近，并且在现场很难测量控制因素。进一步加剧了这些困难的事实是，磨损率很小，因此需要数十年或几个世纪才能通过，然后才能测量侵蚀体积。该项目的目的是建立一种数学关系，该数学关系使用一组新型的实验室仪器来描述冰川磨损的物理学，以便可以在数值景观演化模型中实施。在实验室中，可以以准确确定磨损定律所需的精度来控制和测量条件。该项目将支持UW-Madison的研究生和一名本科生，并为Menominee Nation学院的代表性不足的学生提供培训。大型直径的环形剪切设备和UW-Madison的直接剪切设备将用于在岩石床上覆盖碎屑冰上的冰淇淋冰层，这些冰上的冰上融化了形状和构图的岩石床上。通过磨损产生的条纹将使用能够测量侵蚀材料的体积降至10-18立方米的量进行分析。有了测量这些微小体积的能力，可以在相关的时间范围（每个月少于一个月）中进行滑动实验，并且仍会产生足够的磨损体积以确定磨损定律。使用这些仪器，将制定磨损定律，该法律将侵蚀速率与自变量相关联，例如滑动速度，基本熔化，床形，碎屑硬度和碎片浓度。该奖项反映了NSF的法定任务，并被认为是通过该基金会的知识功能和广泛的影响来评估Criteria的智力功能和广泛影响。

项目成果

A power-based abrasion law for use in landscape evolution models

用于景观演化模型的基于功率的磨损定律

• DOI: 10.1130/g50673.1
• 发表时间: 2023
• 期刊: Geology
• 影响因子: 5.8
• 作者: Hansen, D.D.;Brooks, J.P.;Zoet, L.K.;Stevens, N.T.;Smith, L.;Bate, C.E.;Jahnke, B.J.
• 通讯作者: Jahnke, B.J.