Collaborative Research: Volatile sources, eruption triggers, and magma ascent rates for mafic alkaline magmas at Nyiragongo and Nyamulagira volcanoes, DR Congo, East African Rift

合作研究：刚果民主共和国、东非大裂谷尼拉贡戈火山和尼亚穆拉吉拉火山的镁铁质碱性岩浆的挥发性来源、喷发触发因素和岩浆上升速率

• 批准号: 2043066
• 负责人: Paul Wallace
• 金额: $ 22.72万
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-05-01 至 2025-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2043066&HistoricalAwards=false
• 关键词: Collaborative; Research; Volatile; sources; eruption

Nyiragongo and Nyamulagira, in the East African Rift, are two of the most active volcanoes in the world, and they pose major hazards to large populations living nearby. Many volcanoes that pose great risks to large populations are well studied and highly monitored with scientific instruments, but there is still a fundamental lack of understanding of many basic aspects of the Nyiragongo and Nyamulagira systems. This investigation will improve our understanding of these systems by focusing on (1) how magma forms beneath the two volcanoes, (2) how deeply and for how long magma is stored beneath the volcanoes before eruption, (3) what triggers eruptions to occur on the flanks of the volcanoes, in and near populated areas, and (4) how fast magma moves towards the surface during an eruption and how much warning time people would have in advance of an eruption. In addition to these aspects focused on hazards, this project will investigate the source of the carbon that is released as carbon dioxide by these volcanoes. Large amounts of carbon are likely stored in solid minerals inside the Earth beneath thick, old continental crust like that in East Africa, and when the crust gets pulled apart by rifting as in the East African Rift, the carbon contributes to magma formation. Nyiragongo is one of the largest emitters of carbon dioxide gas of any volcano worldwide, and better understanding the connection between carbon in minerals and magma formation beneath this volcano will help us better understand the Earth’s deep carbon cycle. Much of the research for this project will be conducted by graduate students at the University of Oregon and University of Wyoming as part of their scientific training. Collaboration with scientists at the Goma Volcano Observatory in the Democratic Republic of the Congo will include periodic videoconferences to share research results important for volcanic hazards monitoring. Public engagement will include a National Geographic Explorer’s Blog and several short articles for a general audience on volcanic hazards at Nyiragongo and Nyamulagira and release of carbon dioxide from volcanoes.In detail, the primary goals of this project are (1) to understand the time-integrated effects of lithospheric metasomatism on magma generation beneath Nyiragongo and Nyamulagira, and (2) to use the results as the starting point for a source-to-surface investigation of the plumbing systems, magma storage timescales, eruption triggering processes, and magma ascent rates for these volcanoes. Although these volcanoes are only 15 km apart, their eruption behavior and the types of lava they emit are profoundly different, with Nyiragongo erupting some of the most unusual lava types found anywhere on Earth. To understand the roles of lithospheric mantle and metasomatic veins as magma sources, we will use existing major and trace element and isotopic data together with new data on volatile contents of olivine-hosted melt inclusions to establish parental melt compositions and source lithologies. Our data and modeling approach will also provide important constraints on parental magma CO2 and S concentrations and magma fluxes for each volcano. Our proposed work will use existing tephra and lava samples and will focus on the many parasitic cones and tuff rings on the flanks of Nyiragongo and Nyamulagira, as these erupt more primitive compositions than the volcanoes’ central vents. For investigating the plumbing systems, we will use (1) melt inclusion volatile data to determine crystallization depths, (2) U-series mineral isochrons to determine crystal and magma residence times, (3) mineral zoning and diffusion chronometry to identify recharge and mixing processes that may trigger eruptions and yield precursory seismic signals, and (4) diffusive loss of H from melt inclusions to infer magma ascent rates during eruption, which likely influence explosivity. Our overarching goal is to produce geologically well-grounded, state-of-the-art geochemical and petrological data that improves our understanding of these volcanic systems and thereby improves hazard assessment models.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.

东非裂谷的Nyiragongo和Nyamulagira是世界上最活跃的两个火山，它们对靠近居住的大量人口构成了重大危害。许多对大量人口构成巨大风险的火山都对科学仪器进行了很好的研究，并且对Nyiragongo和Nyamulagira Systems的许多基本方面仍然缺乏理解。这项投资将通过重点关注（1）在两个火山下形成（2）岩浆在爆发前的火山下储存多长时间和多长时间的岩浆，以提高我们对这些系统的理解。喷发。除这些方面的重点是危害外，该项目还将调查这些火山作为二氧化碳释放的碳的来源。大量的碳很可能被储存在厚，旧连续的地壳下的固体矿物质中，如东非，当外壳像东非裂谷一样裂开时，碳构成了岩浆形成。 Nyiragongo是全世界任何火山中二氧化碳气体最大的发射器之一，更好地理解矿物质中的碳与在该火山下方的岩浆形成之间的联系将帮助我们更好地了解地球的深碳循环。该项目的大部分研究将由俄勒冈大学和怀俄明大学的研究生进行，作为其科学培训的一部分。与刚果民主共和国戈马火山天文台的科学家合作将包括定期视频会议，以分享对火山危害监测重要的研究结果。 Public engagement will include a National Geographic Explorer’s Blog and several short articles for a general audience on volcanic hazards at Nyiragongo and Nyamulagira and release of carbon dioxide from volcanoes.In detail, the primary goals of this project are (1) to understand the time-integrated effects of lithospheric metasomatism on magma generation beneath Nyiragongo and Nyamulagira, and (2) to use the结果是源对地面的起点，尽管这些火山相距仅15公里，但它们的喷发行为和它们发出的熔岩类型截然不同，Nyiragongo爆发了一些在地球上任何地方发现的最不寻常的熔岩类型。为了理解岩石圈地幔和代理静脉作为岩浆来源的作用，我们将使用现有的主要和痕量元素和同位素数据以及有关橄榄石托管熔体融合物挥发物含量的新数据来建立父母融合的成分和源岩石岩。我们的数据和建模方法还将为每个火山的父母岩浆二氧化碳以及S浓度和岩浆通量提供重要限制。我们提出的工作将使用现有的Tephra和熔岩样品，并将重点放在Nyiragongo和Nyamulagira侧面的许多寄生锥和凝灰岩环上，因为这些爆发比火山的中央通风孔更原始。 For investigating the plumbing systems, we will use (1) melt inclusion volatile data to determine crystallization depths, (2) U-series mineral isochrons to determine crystal and magma residence times, (3) mineral zoning and diffusion chronometries to identify recharge and mixing processes that may trigger eruptions and yield precursory seismic signals, and (4) differential loss of H from melt inclusions to infer喷发过程中的岩浆上升速率可能会影响爆炸性。我们的总体目标是生产地质良好的，最先进的地球化学和岩石学数据，从而提高了我们对这些火山系统的理解，从而改善了危险评估模型。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子和更广泛影响的评估来审查Criteria，通过评估来通过评估来获得支持。