Helium isotope composition of fluid inclusions hosted in massive sulfides from modern submarine hydrothermal systems / Volker Lüders in Economic geology, Vol. 105 N° 2 (Mars/Avril 2010)  

Public ISBD [article]  inEconomic geology > Vol. 105 N° 2 (Mars/Avril 2010) . - pp. 443-449 Titre : Helium isotope composition of fluid inclusions hosted in massive sulfides from modern submarine hydrothermal systems Type de document : texte imprimé Auteurs : Volker Lüders, Auteur ; Samuel Niedermann, Auteur Année de publication : 2011 Article en page(s) : pp. 443-449 Note générale : Economic geology Langues : Anglais (eng) Mots-clés : Helium Fluid inclusion Sulfides Index. décimale : 553 Géologie économique. Minérographie. Minéraux. Formation et gisements de minerais Résumé : Noble gas compositions of fluid inclusions hosted in sulfides from two modern submarine hydrothermal sites of contrasting tectonic settings have been analyzed. The JADE Field (central Okinawa Trough, Japan) is located in an active intracontinental back-arc basin whereas the SO 134 field is related to the central spreading ridge of the North Fiji Basin, which represents an active, highly mature intra-ocean back-arc system. Previous conventional studies of fluid inclusions have revealed compelling evidence for subcritical phase separation of the hydrothermal fluids at both sites. Elemental abundances of Ne, Ar, Kr, and Xe in fluid inclusions in all studied samples of chalcopyrite and sphalerite from both hydrothermal sites indicate that the heavier noble gases are derived from ambient seawater. In contrast, helium concentrations are 1 to 2 orders of magnitude higher than expected for equilibrium solution in seawater, indicating that helium is predominantly derived from a magmatic source beneath the hydrothermal systems. The 3He/4He ratios in sphalerite-hosted fluid inclusions from the JADE Field and the SO 134 field are similar to those reported from related vent fluids and show that fluid inclusions reliably record the helium isotope ratio of the original hydrothermal fluid. However, in the North Fiji Basin, earlier “black smoker” activity and the formation of Fe-rich “Kies-type”sulfides seems to have been related to a more MORB-like volcanism, whereas the younger recent “white smoker” hydrothermal activity in the North Fiji Basin can be attributed to a hot spot magmatism in the study area. DEWEY : 553 ISSN : 0361-0128 En ligne : http://econgeol.geoscienceworld.org/content/105/2/443.abstract [article] Helium isotope composition of fluid inclusions hosted in massive sulfides from modern submarine hydrothermal systems [texte imprimé] / Volker Lüders, Auteur ; Samuel Niedermann, Auteur . - 2011 . - pp. 443-449. Economic geology Langues : Anglais (eng) in Economic geology > Vol. 105 N° 2 (Mars/Avril 2010) . - pp. 443-449 Mots-clés : Helium Fluid inclusion Sulfides Index. décimale : 553 Géologie économique. Minérographie. Minéraux. Formation et gisements de minerais Résumé : Noble gas compositions of fluid inclusions hosted in sulfides from two modern submarine hydrothermal sites of contrasting tectonic settings have been analyzed. The JADE Field (central Okinawa Trough, Japan) is located in an active intracontinental back-arc basin whereas the SO 134 field is related to the central spreading ridge of the North Fiji Basin, which represents an active, highly mature intra-ocean back-arc system. Previous conventional studies of fluid inclusions have revealed compelling evidence for subcritical phase separation of the hydrothermal fluids at both sites. Elemental abundances of Ne, Ar, Kr, and Xe in fluid inclusions in all studied samples of chalcopyrite and sphalerite from both hydrothermal sites indicate that the heavier noble gases are derived from ambient seawater. In contrast, helium concentrations are 1 to 2 orders of magnitude higher than expected for equilibrium solution in seawater, indicating that helium is predominantly derived from a magmatic source beneath the hydrothermal systems. The 3He/4He ratios in sphalerite-hosted fluid inclusions from the JADE Field and the SO 134 field are similar to those reported from related vent fluids and show that fluid inclusions reliably record the helium isotope ratio of the original hydrothermal fluid. However, in the North Fiji Basin, earlier “black smoker” activity and the formation of Fe-rich “Kies-type”sulfides seems to have been related to a more MORB-like volcanism, whereas the younger recent “white smoker” hydrothermal activity in the North Fiji Basin can be attributed to a hot spot magmatism in the study area. DEWEY : 553 ISSN : 0361-0128 En ligne : http://econgeol.geoscienceworld.org/content/105/2/443.abstract

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