Collaborative Research: Linking climate-driven changes in erosion to tectonic processes along the southern Alaska Margin

合作研究：将气候驱动的侵蚀变化与阿拉斯加南部边缘的构造过程联系起来

• 批准号: 1434402
• 负责人: John Jaeger
• 金额: $ 5.59万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1434402&HistoricalAwards=false
• 关键词: Collaborative; Research; Linking; climate; driven

One of the most challenging questions in active mountain building is how climate might drive tectonic processes, in the form of mass redistribution. In other words, do climate-driven changes in erosion lead to increased exposure of mountainous belts, and perhaps influence tectonic processes, like uplift and faulting, as predicted by numerical models? The study of this question, by means of observational and analytical data is challenging because most areas where active mountain building is occurring are covered by remnant glaciers and glaciated landscapes from the end of the Neogene period (23 ? 2.5 million years ago). The St. Elias mountain belt, in southeast Alaska, is a prime location to address this question due to its extensive glaciation. The recent erosional record of this active mountain range is stored in the Gulf of Alaska and was recovered during Integrated Ocean Drilling Program (IODP) Expedition 341. Integrated analysis of deep-sea core material obtained from drilling at the continental shelf, slope, and the deep-sea Surveyor Fan will provide means to quantify the effect of global and local climate changes on the erosional and structural evolution of a mountain range. The youthfulness of the St. Elias belt, along with high rates of tectonic and erosional processes, and its close proximity of the Gulf of Alaska provide an ideal natural setting to study climate-tectonic interactions. Long-standing debates exist in the Earth sciences on whether Neogene climate change affects rates of surface processes, such as erosion, and consequently influences tectonic processes, such as faulting, through redistribution of mass. The proposed study will test the hypothesis that an increase in glacial erosion has led to focused exhumation in the core of the St. Elias orogeny as proposed by numerical and analytical data. Two possible target regions have been suggested where a tectonic-climate feedback may have developed: in the fold-thrust belt and at the indenting Yakutat plate corner. The wealth of existing onshore geo- and thermochronological data provide a comprehensive picture of the current spatial pattern of exhumation rates, but the quantification of changes in rates and patterns through time has been challenging. The research team?s approach is to investigate the offshore sedimentary record of the St. Elias orogeny deposited in the Gulf of Alaska. This orogeny developed during a period of significant global climate change, including the intensification of Northern Hemisphere glaciation (iNHG) at the Plio-Pleistogene transition (PPT), ~2.6 Ma, and the mid-Pleistocene transition (MPT) from 1.2 to 0.7 Ma, but also a change of local climate resulting in alpine glaciers, perhaps as early as the Late Miocene/Pliocene (6.5 Ma). The high-resolution magnetostratigraphic and biostratigraphic age control from the IODP Expedition 341 cores allow close linking of changes in sedimentary lithofacies and textures, provenanace, exhumation, and sediment routing and distribution, to test the record of climate-tectonic interactions along the southern Alaska margin. The integration of Gulf of Alaska seismic reflection data with the age and provenance control from the 341 cores allow examination of sediment mass flux in the regional offshore depositional system, the Surveyor Fan, from a 3-D perspective through time.

活跃山区建筑中最具挑战性的问题之一是气候如何以大规模再分配形式推动构造过程。换句话说，气候驱动的侵蚀的变化是否会导致山皮带的暴露增加，并且可能像数值模型所预测的那样影响构造过程，例如隆起和断层？通过观察和分析数据对这个问题进行的研究具有挑战性，因为从新金元期结束（23？250万年前）开始，大多数发生了活跃山地建筑的地区都被残留的冰川和冰川景观所覆盖。阿拉斯加东南部的圣埃利亚斯山带是由于广泛的冰川而解决这个问题的主要地点。该活动山脉的最新侵蚀记录存储在阿拉斯加湾，在综合海洋钻井计划（IODP）探险341中被回收。对从大陆架子，坡度，坡度和深海测量师在钻井中获得的深海核心材料的综合分析将提供量化全球和当地气候变化的效果的意义上的山地和山脉范围的效果。圣埃利亚斯带的年轻人，以及高度的构造和侵蚀过程，以及阿拉斯加湾的近距离，为研究气候构造相互作用提供了理想的自然环境。地球科学中存在长期的辩论，即新近纪气候变化是否会影响侵蚀率（例如侵蚀）的速率，并通过质量重新分布来影响构造过程，例如断层。拟议的研究将检验以下假设：冰川侵蚀的增加导致了数值和分析数据所提出的St. Elias造口核心的聚焦挖掘。已经提出了两个可能的目标区域，其中可能已经形成了构造气候反馈的地方：在折叠式带和缩进的yakutat板角。现有的陆上地理和热量学数据的财富提供了当前空间挖掘率模式的全面图景，但是随着时间的推移，速率和模式的变化量化始终具有挑战性。研究团队的方法是调查阿拉斯加湾沉积的圣埃里亚斯造山运动的近海沉积记录。在全球气候变化的重大变化时期，这种造山基因在Plio-Pleistogene过渡（PPT），〜2.6 MA的北半球冰川（INHG）的强度以及中期过渡（MPT）以及从Alpine glaciers（6. 6. 6. 6. 6. 6. 6.）变化而变化。 IODP Expedition 341核心的高分辨率磁层学和生物地层年龄控制允许与沉积岩相和质地的变化紧密联系，Provenanace，Provenanace，Dusiment Routing and Pressign and Spristion和分布，以测试沿南阿拉斯克（Alaska）南部Alaska Margin的气候相互作用的记录。阿拉斯加地震反射数据与341个核心的年龄和出处控制的整合允许从3-D角度贯穿区域近海沉积系统中的沉积物质量通量。