Southernmost Patagonia: The Connection Between Magmatism, Subduction Zone, Slab Window and Sub-continental Mantle Lithosphere

最南端的巴塔哥尼亚：岩浆作用、俯冲带、板片窗和次大陆地幔岩石圈之间的联系

• 批准号: 1829464
• 负责人: Alberto Saal
• 金额: $ 31.16万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-07-01 至 2023-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1829464&HistoricalAwards=false
• 关键词: Southernmost; Patagonia; Connection; Between; Magmatism

The Earth's mantle represents approximately 82% by volume and 68% by mass of the Earth, and therefore, it influences the movement of tectonic plates, earthquakes and volcanism on the surface. A fundamental step to understand the composition and nature of the Earth's mantle from the study of basaltic lavas (partial melts of the mantle) is to establish the budget and distribution of volatiles (hydrogen, carbon, fluorine, chlorine, sulfur) in the Earth's interior. Volatiles influence mantle melting, magma crystallization, magma migration and volcanic eruption, and their abundances and spatial distribution provide important constraints on models of mantle flow and temperature. Moreover, volatiles are key constituents of the Earth's atmosphere and oceans and, thus, constraining the cycling of volatiles between the Earth's interior and surface is of fundamental importance to understand the long-term evolution of our planet, as they fundamentally affect plate tectonics, climate, and habitability. The project will support an African-American female graduate student, an Indian research scientist and a Hispanic Professor at Brown University. It promotes the collaboration with geochemists from nine institutions from three different countries: USA, Argentina and Chile, and will enhance the infrastructure for research and education at Brown University, Oregon State University and Woods Hole Oceanographic Institution. Communication of results will occur through: 1) peer-reviewed journals, presentations at conferences and invited university lectures, 2) hands-on science learning activities for local elementary and high school classes, and 3) outreach to the general audience through public lectures.Diverse hypotheses have been proposed for the origin of the magmatism in southern Patagonia, from flux melting of the mantle wedge during devolatilization of the subducted Nazca and Antarctic plate, to adiabatic decompression melting of a carbonated and hydrous asthenosphere upwelling through the slab window, to melting of a volatile-rich metasomatized subcontinental lithospheric mantle. All proposed hypotheses invoke the role of volatiles. Surprisingly, data on the volatile contents of basalts and mantle xenoliths from this region are non-existent. This is a glaring omission from the geochemical data given the importance of volatiles. The focus of this study will be to examine the regional and temporal variations in volatile contents and microstructure of geochemically well-characterized Eocene-recent basalts and associated mantle xenoliths co-located with the seismic array from southern Patagonia. The lavas and their xenoliths in this region represent smaller melt volumes tapped locally from areas lacking steady-state magma chambers, experience relatively less mixing and differentiation, and offer the best opportunity to determine the composition, lithology and volatile contents of the mantle sources. The integration of these geochemical and microstructural data to a previously funded seismic experiment will enable better constraints on the temperature, composition, viscosity and density structure of the mantle beneath southern Patagonia.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.

地幔约占地球体积的82%和质量的68%，因此，它影响着地表的构造板块运动、地震和火山活动。 通过研究玄武岩熔岩（地幔部分熔化）来了解地幔的成分和性质的一个基本步骤是确定地球内部挥发物（氢、碳、氟、氯、硫）的预算和分布。挥发分影响地幔熔融、岩浆结晶、岩浆迁移和火山喷发，其丰度和空间分布对地幔流动和温度模型提供重要约束。此外，挥发物是地球大气和海洋的关键成分，因此，限制挥发物在地球内部和表面之间的循环对于了解地球的长期演化至关重要，因为它们从根本上影响板块构造、气候和可居住性。该项目将支持布朗大学的一名非裔美国女研究生、一名印度研究科学家和一名西班牙裔教授。它促进与来自美国、阿根廷和智利三个不同国家的九个机构的地球化学家的合作，并将加强布朗大学、俄勒冈州立大学和伍兹霍尔海洋研究所的研究和教育基础设施。 结果的交流将通过以下方式进行：1) 同行评审期刊、会议演讲和受邀大学讲座，2) 当地小学和高中课堂的实践科学学习活动，以及 3) 通过公开讲座向广大观众进行宣传。对于巴塔哥尼亚南部岩浆作用的起源，人们提出了多种假设，即俯冲地幔蒸发过程中地幔楔的通量熔化。 纳斯卡和南极板块，到通过板片窗上升的碳酸化和含水软流圈的绝热减压熔融，到富含挥发物的交代化的次大陆岩石圈地幔的熔融。所有提出的假设都涉及挥发物的作用。令人惊讶的是，关于该地区玄武岩和地幔捕虏体挥发物含量的数据并不存在。考虑到挥发物的重要性，这是地球化学数据中的明显遗漏。这项研究的重点将是研究地球化学特征良好的始新世近代玄武岩和与巴塔哥尼亚南部地震阵列位于同一位置的相关地幔捕虏体的挥发物含量和微观结构的区域和时间变化。该地区的熔岩及其捕虏体代表了从缺乏稳态岩浆房的地区局部开采的较小熔体体积，经历了相对较少的混合和分异，并为确定地幔来源的成分、岩性和挥发性含量提供了最佳机会。将这些地球化学和微观结构数据整合到先前资助的地震实验中，将能够更好地限制巴塔哥尼亚南部地幔的温度、成分、粘度和密度结构。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点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

The Signature of Metasomatized Subcontinental Lithospheric Mantle in the Basaltic Magmatism of the Payenia Volcanic Province, Argentina

• DOI: 10.1029/2021gc010071
• 发表时间: 2022-01-01
• 期刊: GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS
• 影响因子: 3.5
• 作者: Chilson-Parks，Benjamin H.;Calabozo，Fernando M.;Frey，Frederick A.
• 通讯作者: Frey，Frederick A.

The volcanic evolution of the Meseta del Lago Buenos Aires, Patagonia: subduction to slab window volcanism

巴塔哥尼亚布宜诺斯艾利斯 Meseta del Lago 的火山演化：俯冲到板窗火山作用

• 发表时间: 2023
• 期刊: Goldschmidt Conference Archive
• 作者: I Guest, AE Saal

Evidence of South American lithosphere mantle beneath the Chile mid-ocean ridge

• DOI: 10.1016/j.epsl.2023.118320
• 发表时间: 2023-10
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: S. Mallick;Sophie E. Kuhl;A. Saal;E. Klein;W. Bach;B. Monteleone;J. Boesenberg

Olivine-Hosted Melt Inclusions from the Andean Back Arc (34º-38ºS)

来自安第斯山后弧（南纬 34°-38°）的橄榄石熔融包裹体

• 发表时间: 2019
• 期刊: Goldschmidt Conference Archive
• 作者: Chilson-Parks, B. H.