EaGER:The influence of CO2 solubility on trace element partitioning in clinopyroxene-alkali basalt systems: towards the development of a magmatic carbon meter

EaGER：二氧化碳溶解度对单斜辉石-碱性玄武岩系统中微量元素分配的影响：致力于开发岩浆碳计

• 批准号: 1057611
• 负责人: Julia Bryce
• 金额: $ 4.5万
• 依托单位: University of New Hampshire
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1057611&HistoricalAwards=false
• 关键词: EaGER; influence; CO2; solubility; trace

This EaGER will support a feasibility study to evaluate the influence of carbon dioxide (CO2) on the concentration of trace elements in clinopyroxene, in equilibrium with basaltic magma. The ultimate goal of the experimental plan is to assess if the trace element compositions recorded in clinopyroxene (cpx) may serve as a proxy for magmatic CO2. If successful, results from the study could be applied both to those wishing to decipher the source history of a magma as well as the Earth's degassing history. The proposed research plan will complement to existing experiments in CO2-diopside-albite ternary systems that show a large variation in cpx-melt partitioning for alkali, alkaline earth and high field strength elements between carbonatitic and silicate liquids. Since CO2 enrichment is often concomitant with water enrichment in mafic lavas, the experimental design also includes experiments with varying water content so that it is possible to assess the role of dissolved water and carbonate on elemental partitioning. The target starting composition for this pilot study will be chosen from an in-hand suite of clinopyroxene-phyric, calcium and sodium-rich alkaline basalts from Mt. Etna, Sicily (MgO ~ 6 wt. %).Reconstructing the history of volatile emissions on Earth is an essential part of understanding climate controls, yet volatile mobility hampers preservation in the rock record. A recent study using large statistical analysis of recent volcanism has linked the latest episode of deglaciation with enhanced subaerial volcanism and, presumably, subsequently increased volcanic carbon dioxide emissions. This potential role of solid Earth carbon storage in promoting deglaciation impacts the long-established argument that climate is controlled by ocean-atmosphere exchange alone. Presently, other than by amassing records of volcanism chronologically constrained to coincide with episodes of deglaciations, it is difficult to test and refine this hypothesis from the rock record alone, largely because CO2 is not quantitatively contained during magma transport at shallow depths, with up to 90% degassed prior to eruption. The proposed research activities seek to identify whether magmatic carbon dioxide contents impact high field strength element chemistry of basaltic magmas, thereby potentially providing a proxy that enables documentation of carbon dioxide contents in magmas. Links with a world-class experimental facility will enhance technique development in newly established laboratories at UNH. The award provides postdoctoral support for a promising female scientist on an interdisciplinary project within a collaborative multi-institutional work group.

这将支持一项可行性研究，以评估二氧化碳(CO2)对与玄武岩岩浆平衡的单斜辉石中微量元素浓度的影响。实验计划的最终目标是评估单斜辉石中记录的微量元素成分是否可以作为岩浆二氧化碳的替代品。如果成功，这项研究的结果可能既适用于那些希望破译岩浆来源历史的人，也适用于那些希望破译地球脱气历史的人。拟议的研究计划将补充现有的二氧化碳-透辉石-钠长石三元系实验，这些实验表明，碱、碱土和高场强元素在碳酸盐和硅酸盐液体之间的CPX熔体分配存在很大差异。由于富二氧化碳通常伴随着镁铁质熔岩中的水富集，实验设计还包括不同水含量的实验，以便有可能评估溶解水和碳酸盐对元素分配的作用。这项初步研究的目标起始成分将从山上的一套单斜辉石-辉石、钙和钠富碱性玄武岩中选择。重建地球上挥发性排放物的历史是理解气候控制的重要部分，但挥发性的流动性阻碍了岩石记录的保存。最近的一项研究使用了对近期火山活动的大规模统计分析，将最近的冰川消融与空中火山活动的增强联系在一起，并推测随后火山二氧化碳排放增加。固体地球碳储存在促进冰川消融方面的这种潜在作用，冲击了长期以来的观点，即气候仅受海洋-大气交换的控制。目前，除了按时间顺序限制与冰川消融时期一致的火山活动记录外，很难仅从岩石记录来检验和完善这一假设，这主要是因为在浅层岩浆输送过程中，二氧化碳没有得到定量控制，高达90%的二氧化碳在喷发前脱气。拟议的研究活动试图确定岩浆二氧化碳含量是否影响玄武岩岩浆的高场强元素化学，从而可能提供一种能够记录岩浆中二氧化碳含量的指标。与世界级实验设施的联系将加强大学新设立的实验室的技术开发。该奖项为一位有前途的女科学家提供博士后支持，她参与了一个多机构协作工作组内的跨学科项目。