Collaborative Research: Magnetotelluric and seismic investigation of arc melt generation, delivery, and storage beneath Okmok volcano

合作研究：奥克莫克火山下方电弧熔体产生、输送和储存的大地电磁和地震调查

• 批准号: 1456749
• 负责人: Clifford Thurber
• 金额: $ 83.73万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-15 至 2022-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1456749&HistoricalAwards=false
• 关键词: Collaborative; Research; Magnetotelluric; seismic; investigation

Part 1The investigators will conduct a magnetotelluric (MT) survey at Okmok volcano in the Aleutian arc in order to characterize the magmatic system beneath the volcano. New onshore passive seismic and MT data and offshore MT data will be collected to test hypotheses regarding the role of slab fluids in arc melt generation, melt migration within the crust, and the crustal magmatic plumbing and storage system beneath an active caldera. The project will support a female early career investigator, and several graduate and undergraduate students providing the latter hands-on research at sea. Data from this project is planned to be incorporated into undergraduate Earth Sciences courses and presentations.Part 2The Aleutian volcanic arc is a GeoPRISMS primary investigation site that is tectonically active region considered to be ideal for studying arc magmatism. Okmok, an active volcano located in the central Aleutian arc, is only about 100 km from Dutch Harbor making it a logistically advantageous for an amphibious onshore and offshore geophysical imaging of the arc?s magmatic system. Okmok is also selected due to its known volcanic activity, the presence of a crustal magma reservoir, as inferred from previous studies, and the volcanic hazard it presents, as evidenced by the lack of warning prior to 2008 eruption. It has hosted 2 caldera-forming eruptions (CFE) and is representative of volcanoes both within the Aleutian arc and worldwide that experience long periods of effusive eruptions punctuated by much larger explosive CFE. The project will test hypotheses on the role fluids play in melting the mantle wedge and how melts ascend through the corner flow regime of the mantle wedge. It will also test competing hypotheses about melt migration and storage within the upper mantle and crust and how this impacts explosive CFE. Data collected by this project will be used to map seismic velocity and electrical conductivity variations within the arc, providing unique constraints on temperature, mineralogy and fluid content. These constraints will be used to study the mantle melt flux, its possible storage at the base of the crust, the distribution of partial melt/magma bodies in the mid-upper crust, and the thermal and mechanical properties of the upper crust beneath the caldera.Broader Impacts: The proposed work would help improve our understanding of magma storage and transport and its implications on volcanic hazards at Okmok volcano. A female early career investigator and three graduate students (1 Scripps; 2 UW-Madison) would be supported. Seven undergraduate students would be supported (partially through funds from this project and via Scripps NSF REU supported SURF program) to participate in onshore/offshore fieldwork. Data from this project will be incorporated into undergraduate Earth Sciences courses and presentations will be given at local K-12 schools and via live webinars to a few Alaskan schools. A short course on MT methods will be given at UW-Madison and a computer display for this project will be created for the UW Geology Museum?s Active Earth display.

第 1 部分 研究人员将在阿留申岛弧的奥克莫克火山进行大地电磁 (MT) 勘测，以表征火山下方的岩浆系统。将收集新的陆上被动地震和大地电磁数据以及海上大地电磁数据，以检验有关板片流体在电弧熔融生成、地壳内熔融迁移以及活动火山口下方的地壳岩浆管道和存储系统中的作用的假设。该项目将支持一名女性早期职业调查员，以及几名研究生和本科生，为后者提供海上实践研究。该项目的数据计划纳入本科生地球科学课程和演示中。第 2 部分阿留申火山弧是 GeoPRISMS 的主要调查地点，该区域是构造活跃的区域，被认为是研究弧岩浆作用的理想场所。奥克莫克是一座位于阿留申岛弧中部的活火山，距离荷兰港仅约 100 公里，这使得它对于对该弧的岩浆系统进行两栖陆上和海上地球物理成像具有后勤优势。选择奥克莫克的另一个原因是其已知的火山活动、根据之前的研究推断存在地壳岩浆库，以及它所带来的火山危害（2008 年喷发前缺乏预警就证明了这一点）。它曾发生过两次破火山口形成喷发 (CFE)，是阿留申岛弧内和全世界火山的代表，这些火山经历了长时间的喷发，期间夹杂着更大规模的爆炸性 CFE。该项目将测试有关流体在地幔楔熔化过程中所起的作用以及熔体如何通过地幔楔角流态上升的假设。它还将测试有关上地幔和地壳内熔体迁移和储存的相互竞争的假设，以及这如何影响爆炸性 CFE。该项目收集的数据将用于绘制弧内的地震速度和电导率变化图，从而提供对温度、矿物学和流体含量的独特约束。这些约束将用于研究地幔熔体通量、其在地壳底部可能的储存、中上地壳中部分熔体/岩浆体的分布以及破火山口下方上地壳的热和机械特性。 更广泛的影响：拟议的工作将有助于提高我们对岩浆储存和运输及其对奥克莫克火山火山灾害的影响的理解。一名女性早期职业调查员和三名研究生（1 名斯克里普斯；2​​ 名威斯康星大学麦迪逊分校）将得到支持。将支持七名本科生（部分通过该项目的资金以及斯克里普斯 NSF REU 支持的 SURF 项目）参加陆上/海上实地考察。该项目的数据将纳入本科生地球科学课程，并将在当地 K-12 学校进行演示，并通过现场网络研讨会向一些阿拉斯加学校进行演示。威斯康星大学麦迪逊分校将举办有关 MT 方法的短期课程，并将为威斯康星大学地质博物馆的 Active Earth 显示创建该项目的计算机显示。