Submarine magmatic-hydrothermal systems at the Monowai volcanic center, Kermadec arc / Matthew I. Leybourne in Economic geology, Vol. 107 N° 8 (Décembre 2012)  

Public ISBD [article]  inEconomic geology > Vol. 107 N° 8 (Décembre 2012) . - pp. 1669-1694 Titre : Submarine magmatic-hydrothermal systems at the Monowai volcanic center, Kermadec arc Type de document : texte imprimé Auteurs : Matthew I. Leybourne, Auteur ; Ulrich Schwarz-Schampera, Auteur ; Cornel E. J. de Ronde, Auteur Année de publication : 2013 Article en page(s) : pp. 1669-1694 Note générale : economic geology Langues : Anglais (eng) Mots-clés : Monowai volcanic center  magmatic hydrothermal systems Résumé : The Monowai volcanic center is located at the midpoint along the ∼2,530-km-long Tonga-Kermadec arc system. The Monowai volcanic center is comprised of a large elongate caldera (Monowai caldera area ∼35 km2; depth to caldera floor 1,590 m), which has formed within an older caldera some 84 km2 in area. To the south of this nested caldera system is a large composite volcano, Monowai cone, which rises to within ∼100 m of the sea surface and which has been volcanically active for the past several decades. Mafic volcanic rocks dominate the Monowai volcanic center; basalts are the most common rock type recovered from the cone, whereas basaltic andesites are common within the caldera. Hydrothermal plume mapping has shown at least three major hydrothermal systems associated with the caldera and cone: (1) the summit of the cone, (2) low-temperature venting ( We believe the Monowai volcanic center is host to a robust magmatic-hydrothermal system, with significant differences in the style and composition of venting at the cone and caldera sites. At the cone, the large shifts in pH, very high δ3He% values, elevated TDFe and TDFe/TDMn, and the H2S- and CH4-rich nature of the plume fluids, together with elevated Ti, P, V, S, and Al in hydrothermal particulates, indicates significant magmatic volatile ± metal contributions in the hydrothermal system coupled with aggressive acidic water-rock interaction. By contrast, the caldera has low TDFe/TDMn in hydrothermal plumes; however, elevated Al and Ti contents in caldera particulate samples, combined with the presence of alunite, pyrophyllite, sulfide minerals, and native sulfur in samples from Mussel Ridge suggest past, and perhaps recent, acid volatile-rich venting and active Fe sulfide formation in the subsurface. DEWEY : 553 ISSN : 0361-0128 En ligne : http://economicgeology.org/content/107/8/1669.short [article] Submarine magmatic-hydrothermal systems at the Monowai volcanic center, Kermadec arc [texte imprimé] / Matthew I. Leybourne, Auteur ; Ulrich Schwarz-Schampera, Auteur ; Cornel E. J. de Ronde, Auteur . - 2013 . - pp. 1669-1694. economic geology Langues : Anglais (eng) in Economic geology > Vol. 107 N° 8 (Décembre 2012) . - pp. 1669-1694 Mots-clés : Monowai volcanic center  magmatic hydrothermal systems Résumé : The Monowai volcanic center is located at the midpoint along the ∼2,530-km-long Tonga-Kermadec arc system. The Monowai volcanic center is comprised of a large elongate caldera (Monowai caldera area ∼35 km2; depth to caldera floor 1,590 m), which has formed within an older caldera some 84 km2 in area. To the south of this nested caldera system is a large composite volcano, Monowai cone, which rises to within ∼100 m of the sea surface and which has been volcanically active for the past several decades. Mafic volcanic rocks dominate the Monowai volcanic center; basalts are the most common rock type recovered from the cone, whereas basaltic andesites are common within the caldera. Hydrothermal plume mapping has shown at least three major hydrothermal systems associated with the caldera and cone: (1) the summit of the cone, (2) low-temperature venting ( We believe the Monowai volcanic center is host to a robust magmatic-hydrothermal system, with significant differences in the style and composition of venting at the cone and caldera sites. At the cone, the large shifts in pH, very high δ3He% values, elevated TDFe and TDFe/TDMn, and the H2S- and CH4-rich nature of the plume fluids, together with elevated Ti, P, V, S, and Al in hydrothermal particulates, indicates significant magmatic volatile ± metal contributions in the hydrothermal system coupled with aggressive acidic water-rock interaction. By contrast, the caldera has low TDFe/TDMn in hydrothermal plumes; however, elevated Al and Ti contents in caldera particulate samples, combined with the presence of alunite, pyrophyllite, sulfide minerals, and native sulfur in samples from Mussel Ridge suggest past, and perhaps recent, acid volatile-rich venting and active Fe sulfide formation in the subsurface. DEWEY : 553 ISSN : 0361-0128 En ligne : http://economicgeology.org/content/107/8/1669.short

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