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

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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.