Carbon recycling by arc magmatism: an assessment from experimentally homogenized melt inclusions in olivine

电弧岩浆作用的碳回收：对橄榄石中实验均质熔体包裹体的评估

• 批准号: 429657633
• 负责人: Professor Dr. Roman Botcharnikov, Ph.D.
• 金额: --
• 依托单位: Vernadsky Institute of Geochemistry and Analytical Chemistry
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/429657633?language=en
• 关键词: Carbon; recycling; arc; magmatism; assessment

Subduction zones are tectonic setting of a large-scale CO2 recycling between the exosphere and the mantle on Earth that has a key influence on building and sustaining a habitable planet. A large amount of carbon from atmosphere and hydrosphere, stored in sediments and oceanic lithosphere, can be returned to the mantle via subduction and partly recycled back to the surface by arc volcanism. The extent and the efficiency of CO2 output by arc volcanism remains poorly constrained to date due to the scarcity of accurate data on CO2 abundance in parental arc melts, and the available models mostly rely on high-temperature volcanic gas data. This bilateral German-Russian research project aims at providing fundamental and currently missing information on the CO2 cycle at subduction zones and focuses on the accurate determination of the initial concentration of CO2 in parental magmas from 3 active volcanic arcs: – Kuril-Kamchatka, Central American and Calabrian arcs – representing the entire range of CO2/S ratios in volcanic gases globally. Our goal will be achieved by analyzing the volatile contents in melt inclusions in olivine. To eliminate post-entrapment modifications of melt inclusions, they will be completely homogenized by heating and re-hydration using state-of-the-art one-atmosphere and high-pressure experiments, providing the possibility for direct analytical determination of bulk CO2 content in melt inclusions. The data will be used to quantify the transfer of CO2 in representative arc magmas with various contribution of carbonated material in the source. The obtained results will be crucial to test the proposed direct link of the volcanic gas chemistry with the composition of magmatic melts. Furthermore, they will help to identify potential trace element and isotope proxies for CO2 concentrations in magmas, allowing us to estimate input and output CO2 fluxes at subduction by using other geochemical parameters.

俯冲带是地球外逸层和地幔之间大规模二氧化碳循环的构造环境，对建立和维持宜居行星具有关键影响。大气和水圈中的大量碳储存在沉积物和海洋岩石圈中，通过俯冲作用返回地幔，部分通过弧火山作用再循环回到地表。由于缺乏准确的母弧熔体中CO2丰度数据，迄今为止，弧火山作用的CO2输出范围和效率仍然很差，现有的模型主要依赖于高温火山气体数据。这个德国和俄罗斯的双边研究项目旨在提供关于俯冲带二氧化碳循环的基本和目前缺失的信息，并侧重于准确确定来自3个活跃火山弧的母岩浆中二氧化碳的初始浓度：千岛群岛-堪察加、中美洲和卡拉布里亚弧，代表了全球火山气体中二氧化碳/硫比的整个范围。我们的目标将通过分析橄榄石熔体包裹体中的挥发性含量来实现。为了消除熔体包裹体的捕获后修饰，它们将通过最先进的单气氛和高压实验加热和再水化来完全均匀化，从而为直接分析测定熔体包裹体中的散装二氧化碳含量提供可能。这些数据将用于量化具有代表性的弧岩浆中CO2的转移，其来源中有不同的碳酸物质贡献。所得结果对于检验火山气体化学与岩浆熔体组成之间的直接联系至关重要。此外，它们将有助于确定岩浆中CO2浓度的潜在微量元素和同位素代用物，使我们能够利用其他地球化学参数估计俯冲时的输入和输出CO2通量。