Carbon dioxide in geochemically heterogeneous melt inclusions from Mount Etna, Italy

Salem, L. C. and Edmonds, M. and Corsaro, R. A. and Maclennan, J. (2019) Carbon dioxide in geochemically heterogeneous melt inclusions from Mount Etna, Italy. Geochemistry, Geophysics, Geosystems. ISSN 1525-2027 DOI https://doi.org/10.1029/2018GC008027

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Official URL: https://doi.org/10.1029/2018GC008027

Abstract

Mt. Etna is among the largest global volcanic outgassers with respect to carbon and sulfur, yet questions remain regarding the source of these volatiles and their systematics in the crust and mantle. The importance of heterogeneous mantle sources, mixing, crustal assimilation and disequilibrium degassing are investigated using melt inclusions erupted during the A.D. 1669 eruption of Mt. Etna, Italy. We find that the melt inclusion compositions define a mixing array between two geochemically distinct melts. One end‐member melt is depleted in light rare Earth elements (LREE) and enriched in strontium (Sr), carbon and sulfur; the other is enriched in LREE and depleted in Sr, carbon and sulfur. We infer, through modeling, that the melts may either have been generated by melting a mantle source that includes a recycled oceanic crustal component; or they may have assimilated carbonate material in the crust. The resulting LREE‐depleted, Sr‐enriched melts were also alkali‐rich, which enhanced the solubility of carbon and sulfur. The LREE‐depleted, Sr‐ and volatile‐rich melt ascended through the crust and likely became supersaturated with respect to CO2 and sulfur. The melt intruded into a LREE‐enriched, relatively degassed magma body in the shallow crust, cooled rapidly and vesiculated, likely triggering eruption. The melt inclusion array trapped by growing olivines during this intrusion process records a snapshot of incomplete mixing between the two melts. Mt. Etna is renowned for the large increases in CO2 gas fluxes shortly before and during eruption. The intrusion of supersaturated, CO2‐enhanced magmas into shallow reservoirs may be a common process at Mt. Etna.

Item Type: Article
Uncontrolled Keywords: 2019AREP; IA75
Subjects: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Divisions: 02 - Geodynamics, Geophysics and Tectonics
08 - Green Open Access
12 - PhD
Journal or Publication Title: Geochemistry, Geophysics, Geosystems
Identification Number: https://doi.org/10.1029/2018GC008027
Depositing User: Sarah Humbert
Date Deposited: 27 Jun 2019 17:28
Last Modified: 03 Dec 2019 01:00
URI: http://eprints.esc.cam.ac.uk/id/eprint/4506

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