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Arrival of extremely volatile-rich high-Mg magmas changes explosivity of Mount Etna

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Kamenetsky, VS and Pompilio, M and Metrich, N and Sobolev, AV and Kuzmin, DV and Thomas, R (2007) Arrival of extremely volatile-rich high-Mg magmas changes explosivity of Mount Etna. Geology, 35 (3). pp. 255-258. ISSN 0016-7606

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Abstract

The volcanic hazard potential of Mount Etna volcano is currently nourished by long-lasting, powerful eruptions of basaltic magmas coupled with increased seismicity and ground deformation, and the world's largest discharge of volcanic gases. The current evolutionary cycle of Mount Etna activity is consistent with subduction-related chemical modifications of the mantle source. Arrival of a new mantle-derived magma batch beneath the volcano has been hypothesized, but is still elusive among the erupted products. Here we demonstrate petrological and geochemical affinities between the magmas supplying modern eruptions and high-Mg, fall-stratified (FS) basalts ejected violently similar to 4 k.y. ago. The FS primitive magmas (similar to 13 wt% MgO) are characteristically volatile enriched (at least 3.8 wt% H2O and 3300 ppm CO2), and bear a trace element signature of a garnet-bearing, metasomatized source (high Gd/Yb, K/La, U/Nb, Pb/Ce, Ca/Al). They started crystallizing olivine (Fo(91)), clinopyroxene (Mg# 92.5), and Cr spinel deep in the plumbing system (> 5 kbar), contributing to the cumulate piles at depth and to differentiated alkaline basalt and trachybasalt magmas in the shallow conduit. Continuous influx of mantle-derived, volatile-rich magmas, such as those that supplied the FS fallout, provides a good explanation for major compositional and eruptive features of Mount Etna.

Item Type: Article
Keywords: mount etna, volcano, picrite, melt inclusions, volatiles, degassing, mantle, metasomatism, mt etna, melt inclusions, plumbing system, evolution, constraints, eruptions, insights, volcano, lavas, CO2
Journal or Publication Title: Geology
Page Range: pp. 255-258
ISSN: 0016-7606
Identification Number - DOI: 10.1130/G23163A.1
Date Deposited: 14 Nov 2007 01:50
Last Modified: 18 Nov 2014 03:24
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