Volatile (sulphur and chlorine), major, and trace element geochemistry of mafic to intermediate tephras from the Chilean Southern Volcanic Zone (33–43°S).

Wehrmann, Heidi, Hoernle, Kaj , Jacques, Guillaume, Garbe-Schönberg, Dieter, Schumann, Kai, Mahlke, Julia and Lara, L. E. (2014) Volatile (sulphur and chlorine), major, and trace element geochemistry of mafic to intermediate tephras from the Chilean Southern Volcanic Zone (33–43°S). International Journal of Earth Sciences, 103 (7). pp. 1945-1962. DOI 10.1007/s00531-014-1006-9.

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Abstract

Here we present the first systematic investigation of volatile geochemistry along the Southern Volcanic Zone (SVZ) of Chile. Holocene olivine-hosted melt inclusions in the most mafic tephras sampled from 16 volcanoes along the volcanic front of the SVZ between 33°S and 43°S were analysed for pre-eruptive sulphur, chlorine, and major element contents. These results are combined with trace element compositions of the host whole rocks. The highest fractionation-corrected gas contents occur in the least-degassed melt inclusions from small monogenetic cones of Los Hornitos, Cabeza de Vaca, and Apagado from both the transitional and the southern-central SVZ, reaching ~3,000 μg/g S and 1,400 μg/g Cl, while the lowest abundances of ~1,100 μg/g S and ~600 μg/g Cl were found in the central SVZ at Volcán Lonquimay, Volcán Llaima, and Volcán Villarrica. Chlorine co-varies with trace element indicators for the degree of melting and/or source enrichment, such that the lowest Cl contents are found in high-degree melts from the most depleted mantle sources. The size of the volcanic edifices correlates inversely with Cl abundances in the melt. This could reflect more extensive degassing during ascent through the complex magma plumbing systems beneath the stratovolcanoes or greater dilution during larger degrees of melting of more depleted sources, or a combination of these factors. Compared to other subduction zones, the SVZ melt inclusions exhibit Cl and S abundances in the same range as most of those from the Central American and those from the Marianas arcs.

Document Type: Article
Additional Information: WOS:000343216700014
Keywords: Volcanology; Geochemistry; Chilean Southern Volcanic Zone, melt inclusions, sulphur, chlorine, subduction zone
Research affiliation: OceanRep > SFB 574
Kiel University
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS
OceanRep > SFB 574 > C2
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1007/s00531-014-1006-9
ISSN: 1437-3254
Projects: SFB574, Future Ocean
Contribution Number:
ProjectNumber
SFB 574240
Date Deposited: 22 Mar 2012 08:18
Last Modified: 23 Sep 2019 23:14
URI: http://oceanrep.geomar.de/id/eprint/14002

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