TERRAPUB Geochemical Journal
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Geochemical Journal, Vol. 44 (No. 1), pp. e1-e4, 2010

EXPRESS LETTER

Helium isotopic ratios in fluid inclusions from fluorite-rich Mississippi Valley-Type district of Asturias, northern Spain

Virginia Sánchez,1 Finlay M. Stuart,2 Tomás Martín-Crespo,3 Elena Vindel,1 Mercé Corbella4 and Esteve Cardellach4

1Dept. Cristalografía y Mineralogía, Facultad de Ciencias Geológicas, Universidad Complutense, 28040, Madrid, Spain
2Isotope Geosciences Unit, SUERC, Rankine Avenue, East Kilbride, G750QF, U.K.
3ESCET, E. Departamental II, Universidad Rey Juan Carlos, Móstoles, 28933, Madrid, Spain
4Dept. Geología, Facultat de Ciences, Universitat Autònoma, Bellaterra, 08193 Barcelona, Spain

(Received September 22, 2009; Accepted January 18, 2010; Online published February 4, 2010)

Abstract: Helium isotopes have been measured in fluorite and sulphides from fluorite-rich Mississippi Valley-type (MVT) deposits from Asturias, Spain, in order to assess the involvement of mantle and crust-derived volatiles in the genesis of the deposits. The 3He/4He of the ore fluids are ≤0.1 Ra ruling out a contribution of mantle-derived magmatic helium in the inclusion fluids. Data support a crustal source for the volatiles and is consistent with the existing basinal model for the genesis of the Asturias MVT mineralization by mixing of sedimentary brines with infiltrating superficial fluids.
Key words: fluorite, noble gases, helium isotopes, fluid inclusions, Asturias, MVT deposits


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