Collaborative Research: Transient Landscapes, Temporally Variable Erosion Rates, and the Impact of Glaciation and Climate Change on Landscape Morphodynamics

合作研究：瞬变景观、随时间变化的侵蚀率以及冰川作用和气候变化对景观形态动力学的影响

• 批准号: 1123688
• 负责人: James Spotila
• 金额: $ 31.89万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1123688&HistoricalAwards=false
• 关键词: Collaborative; Research; Transient; Landscapes; Temporally

Collaborative Research: Transient landscapes, temporally variable erosion rates, and the impact of glaciation and climate change on landscape morphodynamics.James Spotila, Virginia TechLewis Owen, University of CincinnatiOver the past two decades, geologists have determined that erosion and climate, processes that work at the Earth?s surface, directly influence plate tectonics and mountain building, processes linked to the dynamics of Earth?s interior (crust and upper mantle). One climatic variation that has enormous influence of the effectiveness of erosion is temperature, as represented by the vast difference between erosion by rivers (i.e. fluvial erosion) and glaciers. A profound global acceleration in erosion several million years ago has been ascribed in countless studies to the onset of global cooling and the expansion of glaciers. This has lead to the idea that glaciers are absolutely efficient agents of erosion, acting like buzz saws that can erode rock as fast as plate tectonics pushes up mountains. Yet when this is examined in detail, there are numerous observations that suggest the behavior is more complex. We have identified heavily glaciated mountain ranges in tectonically active areas that may be eroding very slowly. There are also glaciated mountain ranges that may have experienced rapid erosion, despite being dominated by frozen beds (normally linked to slow erosion) and a lack of tectonic uplift. These observations suggest that there may be complex conditions that operate as thresholds for the onset of the extremely rapid, efficient glacial erosion. To test this, we will quantify what factors act as thresholds that control the response of mountain erosion to glaciation, including the factors of rock uplift rate, precipitation, and tectonic relief. This will be accomplished by expanding the case knowledge of glacial erosion controls, by quantifying chronologies of erosion rate over a range of timescales and erosive depths in four very different mountainous regions that span a range of conditions, including the Chugach and Kenai Ranges in Alaska, northwest Scotland, and the Presidential Range of New England. In each location we will test whether erosion accelerated with the onset of a specific stage of glacial development, by measuring erosion rates using several methods of radiogenic helium thermochronology (million year timescale) and cosmogenic dating, optically stimulated luminescence, and sedimentary records (spanning ten thousand to a hundred years). By contributing to our understanding of erosion, climate, and tectonics, we will in effect help satisfy an innate human curiosity for how the landscape around us formed. We will also enable a better, more predictive understanding for how glacial and alpine landscapes respond to climate change, which is of timely, practical importance. In parallel with our research, our educational and museum outreach program will serve to connect to both students and the general public, kindling curiosity for Earth processes while conveying an experience of how geoscience problems are framed and tested through experimentation.

合作研究：瞬态景观、随时间变化的侵蚀率以及冰川作用和气候变化对景观形态动力学的影响。弗吉尼亚理工大学的詹姆斯·斯波提拉（James Spotila）、辛辛那提大学的刘易斯·欧文（Lewis Owen）在过去的二十年里，地质学家已经确定，侵蚀和气候过程在地球表面，直接影响板块构造和造山运动，以及与地球内部（地壳和上地幔）动力学相关的过程。对侵蚀效果产生巨大影响的一种气候变化是温度，河流侵蚀（即河流侵蚀）和冰川侵蚀之间存在巨大差异。无数研究将数百万年前全球侵蚀的急剧加速归因于全球变冷和冰川扩张。这导致人们认为冰川绝对是有效的侵蚀媒介，它就像电锯一样侵蚀岩石，速度就像板块构造推高山脉一样快。然而，当详细研究这一点时，有大量观察结果表明这种行为更为复杂。我们已经在构造活动活跃的地区发现了严重冰川化的山脉，这些山脉可能正在被缓慢侵蚀。还有一些冰川山脉可能经历了快速侵蚀，尽管主要是冻床（通常与缓慢侵蚀有关）并且缺乏构造隆起。这些观察结果表明，可能存在复杂的条件，作为极快、高效的冰川侵蚀开始的阈值。为了测试这一点，我们将量化哪些因素作为控制山脉侵蚀对冰川作用的响应的阈值，包括岩石抬升率、降水和构造起伏的因素。这将通过扩大冰川侵蚀控制的案例知识来实现​​，通过量化跨越一系列条件的四个截然不同的山区（包括阿拉斯加的楚加奇和基奈山脉）在一系列时间尺度和侵蚀深度上的侵蚀率年表，苏格兰西北部和新英格兰的总统山脉。在每个地点，我们将测试侵蚀是否随着冰川发展特定阶段的开始而加速，通过使用放射成因氦热年代学（百万年时间尺度）和宇宙成因测年、光激发光和沉积记录（跨越十个国家）的多种方法测量侵蚀率。一千年到一百年）。通过促进我们对侵蚀、气候和构造的理解，我们实际上将有助于满足人类对周围景观如何形成的天生好奇心。我们还将更好地、更具预测性地了解冰川和高山景观如何应对气候变化，这具有及时、实际的重要性。在我们的研究的同时，我们的教育和博物馆外展计划将有助于与学生和公众建立联系，激发对地球过程的好奇心，同时传达如何通过实验来构建和测试地球科学问题的经验。