Evaluating the Role of Glaciation on the Structural Configuration of the Southern Alaska Syntaxis

评估冰川作用对阿拉斯加南部共轴结构配置的作用

• 批准号: 1145223
• 负责人: Saad Haq
• 金额: $ 31.9万
• 依托单位: Purdue 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: 2012-09-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1145223&HistoricalAwards=false
• 关键词: Evaluating; Role; Glaciation; Structural; Configuration

The role of glaciation on the tectonic configuration of convergent margins is a first order question that remains largely unanswered. The eastern Gulf of Alaska is arguably the best place on Earth to study the coupling of glacial erosional processes and tectonics. The coastal mountains in this area, the Chugach and St. Elias Ranges, contain the largest non-polar ice fields on earth and are characterized by the most erosive agents on earth, tidewater glaciers, and are part of a wide zone of deformation that forms along the southern Alaska syntaxis. This structural, depositional, and climatic framework of the Gulf of Alaska provide the ideal study area to understand the relationship between glaciation and tectonics. Few places on earth have the extreme exhumation, erosional, and depositional rates that have been documented as in the syntaxial corner. Many recent studies provide evidence for intensified rock uplift in response to focused erosion by glaciers but the structural mechanics that are responsible for the reorganization of the mountain belt are not well understood in Alaska or elsewhere. This project has two basic goals: 1) to refine the structural cross-sections of the region using geologic data and, 2) develop mechanical analog models that account for the role of glacially driven erosion and deposition (amount and location) on the reorganization of deformation along the geologically and geometrically complex plate boundary of the Alaskan margin. Analog modeling will utilize state-of-the-art kinematic analysis to understand the development and evolution of structures.The influence of glaciers in Southern Alaska, and in general, on tectonics is directly related to variations in climate, however, most models for the mechanical development of convergent margins are disconnected from the role of glaciations in mass redistribution and the coupled tectonic response. This modeling study will help to quantify the general mechanical response of Coulomb wedges to highly localized glacial erosion, which occurs on geologically rapid time scales, and more specifically will put constraints on the style and evolution of deformation along the Alaskan convergent margin. This work will help to elucidate both short and long-term response of mountain belts, including changes in uplift and strain patterns, due to rapid loading and unloading, that can occur during periods of rapid climate change. The project has a significant outreach and education component that seeks to increase diversity in the geosciences by working with high school Native American students from rural Alaskan communities.

冰川作用对会聚边缘构造形态的作用是一个一级问题，在很大程度上仍然没有答案。阿拉斯加湾东部可以说是地球上研究冰川侵蚀过程和构造耦合的最佳地点。这一地区的沿海山脉，楚加奇山脉和圣埃利亚斯山脉，包含了地球上最大的非极地冰原，其特征是地球上最具侵蚀性的代理人，冰川，是沿着沿着结形成的广泛变形区的一部分。阿拉斯加湾的这种结构、沉积和气候框架为了解冰川作用和构造之间的关系提供了理想的研究区域。地球上很少有地方有极端的剥露，侵蚀和沉积速率，已被记录为在同轴角。最近的许多研究提供了证据，表明冰川集中侵蚀导致岩石隆起加剧，但阿拉斯加或其他地方对导致山带重组的结构力学还没有很好的了解。该项目有两个基本目标：1）利用地质数据完善该地区的结构横截面，2）开发力学模拟模型，解释冰川驱动的侵蚀和沉积（数量和位置）对阿拉斯加边缘地质和几何复杂板块边界沿着变形重组的作用。模拟建模将利用最先进的运动学分析来了解结构的发展和演变。阿拉斯加南部冰川的影响，以及一般而言，对构造的影响与气候变化直接相关，然而，大多数收敛边缘的机械发展模型与冰川在质量再分配和耦合构造响应中的作用无关。这种建模研究将有助于量化库仑楔的一般机械响应高度本地化的冰川侵蚀，发生在地质快速的时间尺度上，更具体地说，将把约束的风格和演变的变形沿着阿拉斯加收敛边缘。这项工作将有助于阐明山区带的短期和长期反应，包括由于快速加载和卸载而导致的隆起和应变模式的变化，这可能发生在快速气候变化期间。该项目有一个重要的外联和教育组成部分，旨在通过与阿拉斯加农村社区的美国土著高中学生合作，增加地球科学的多样性。