RUI: Tracking magma accumulation and evolution in the Andean Central Volcanic Zone

RUI：追踪安第斯中央火山带的岩浆积累和演化

• 批准号: 2006374
• 负责人: Gary Michelfelder
• 金额: $ 23.87万
• 依托单位: Missouri State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2006374&HistoricalAwards=false
• 关键词: RUI; Tracking; magma; accumulation; evolution

Continental arc volcanoes represent a dramatic surface expression of one of the most significant and fundamental phenomena in global tectonics: the subduction of an oceanic plate beneath a more buoyant continental plate resulting in recycling of crustal material into the convecting mantle, partial melting, and primary basalt production. Moreover, during passage through thick continental crust, subduction zone magmas may substantially differentiate and melt crustal rocks giving rise to the great diversity of igneous lithologies characteristic of earth. Explosive volcanic eruptions at continental arc can have devastating global effects and owe their explosiveness to the composition and volume of magma stored in the crust. The development of large magma storage systems remains largely unknown and very controversial among volcanologists. This project will investigate how accumulated magma is stored and evolves over time. The investigators seek to characterize the processes and timescales of magma storage in the modern magma chambers beneath volcanoes in the Andean Central Volcanic Zone of Chile and Bolivia. Growing evidence suggests that the massive magmatic reservoirs required for largest and most explosive eruptions, such as those in the Central Andean Altiplano-Puna Volcanic Complex, are built rapidly in hot crustal environment. Over the 3-year project, graduate and undergraduate students will expand their research skills by working collaboratively with an international team of geologists seeking to understand the dynamics of crustal melting and magma storage leading to volcanic eruptions. The project emphasizes training in analytical methods in the lab, in the field, and at collaborating facilities.This project will focus on young volcanic rocks from composite volcano complexes in the Andean Central Volcanic Zone of Chile and Bolivia (Aucanquilcha, Ollagüe, Uturuncu, San Pedro-Linzor, Licancabur, Lazufre and Lascar) linked closely in space and time, to address the processes and timescales leading to the buildup of magma and eventual volcanic eruption. The primary intent of this project is to investigate how accumulated magma is stored and evolves over time. This will be accomplished by characterizing the processes and timescales of magma differentiation in the modern magma chambers and determining the influence of regional magma bodies on Central Andes volcanoes. New and existing samples from each center will be used to address three basic questions: 1) how long does magma reside at active individual centers; 2) do magmatic sources and partial melting processes vary systematically with the geochemical evolution of volcanic products; and 3) what is the evidence for involvement regional-scale upper crustal magma reservoirs in controlling eruptive composition? The proposed research will use targeted field sampling, whole rock geochemistry, 40Ar/39Ar geochronology, high precision zircon geochronology/geochemistry and trace element diffusion in plagioclase to address these questions. Ultimately, the dataset produced in this study will provide insight into the generation and diversity of magmas that form continental crust.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.

大陆弧火山是全球构造学中最重要、最基本的现象之一的生动地表表现：一个海洋板块俯冲到一个浮力更强的大陆板块之下，导致地壳物质再循环进入对流的地幔、部分熔融和初级玄武岩的产生。此外，在穿越厚大陆地壳的过程中，俯冲带岩浆可能会对地壳岩石进行大量的分异和熔融，从而导致地球火成岩岩性特征的巨大多样性。大陆弧的爆炸性火山喷发会对全球造成毁灭性的影响，其爆炸性取决于地壳中储存的岩浆的成分和体积。大型岩浆储存系统的发展在很大程度上仍然是未知的，并且在火山学家中非常有争议。这个项目将研究积累的岩浆是如何储存和随着时间的推移而演变的。研究人员试图描述智利和玻利维亚安第斯中央火山区火山下现代岩浆库中岩浆储存的过程和时间尺度。越来越多的证据表明，大型岩浆储层是在炎热的地壳环境中迅速形成的，这些储层是最大规模、最具爆炸性的火山喷发所必需的，比如安第斯山脉中部的Altiplano-Puna火山复合体。在这个为期3年的项目中，研究生和本科生将通过与一个国际地质学家团队合作，寻求了解地壳融化和岩浆储存导致火山爆发的动力学，从而扩大他们的研究技能。该项目强调在实验室、实地和合作设施中对分析方法进行培训。该项目将重点研究智利和玻利维亚安第斯中央火山区（Aucanquilcha, ollag<e:1>, Uturuncu, San Pedro-Linzor, Licancabur， Lazufre和Lascar）复合火山群的年轻火山岩，这些火山群在空间和时间上紧密联系，以解决导致岩浆积聚和最终火山喷发的过程和时间尺度。该项目的主要目的是研究积累的岩浆是如何储存和随着时间的推移而演变的。这将通过描述现代岩浆房中岩浆分化的过程和时间尺度以及确定区域岩浆体对安第斯山脉中部火山的影响来实现。来自每个中心的新样品和现有样品将用于解决三个基本问题：1)岩浆在活跃的单个中心存在多久；2)岩浆来源和部分熔融过程是否随火山产物地球化学演化而系统变化；3)区域尺度上地壳岩浆储层参与控制喷发成分的证据是什么？针对这些问题，拟开展定向野外采样、全岩地球化学、40Ar/39Ar年代学、高精度锆石年代学/地球化学、斜长石微量元素扩散等研究。最终，在这项研究中产生的数据集将提供对形成大陆地壳的岩浆的产生和多样性的深入了解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Editorial: Volcanism in the Central Volcanic Zone of the Andes

社论：安第斯山脉中央火山带的火山活动

• DOI: 10.3389/feart.2023.1130976
• 发表时间: 2023
• 期刊: Frontiers in Earth Science
• 影响因子: 2.9
• 作者: Aguilera, Felipe;Grosse, Pablo;Guzmán, Silvina;Michelfelder, Gary;Taussi, Marco
• 通讯作者: Taussi, Marco