N2, Ar, and He as a tool for discriminating sources of volcanic fluids with application to Vulcano, Italy

Abstract

A detailed analysis of published data on the N 2 , Ar, and He content and Ar and He isotopic composition of fumarolic fluids from Vulcano crater (south Italy) supports a model with two endmembers comprising magmatic and hydrothermal fluids with correspondingly low and high H 2 O content. The magmatic component with the highest 3 He/ 4 He and highest absolute concentrations of N 2 , Ar, and He also has the lowest N 2 /Ar and N 2 /He ratios (∼300 and ∼500, respectively). In contrast, the hydrothermal endmember, with the lower 3 He/ 4 He and lower absolute N 2 , Ar, and He abundances, has high N 2 /Ar (∼1,000) and high N 2 /He (>3,000) ratios. The hydrothermal component is also characterized by the highest 40 Ar/ 36 Ar ratios (>1,000) and is proposed to be the main carrier of metamorphic gases from the arc crust.

Magma-derived CO 2 emissions in the Tengchong volcanic field, SE Tibet: Implications for deep carbon cycle at intra-continent subduction zone

“…Eastward subduction of the Indian continental lithosphere provides recycled crustal materials for generation of enriched mantle wedge, which is considered as source region of the TVF parental Giggenbach and Poreda, 1993;Taran, 2011). Data are shown with previously published data from Shangguan et al (2000), Xu et al (2004), Zhao et al (2011Zhao et al ( , 2012 and Cheng et al (2014).…”

Geochemistry of volcanic and hydrothermal gases of Mutnovsky volcano, Kamchatka: evidence for mantle, slab and atmosphere contributions to fluids of a typical arc volcano

“…Hilton et al (2002) have discussed the importance of these data for He balance in subduction zones and decided do not count this excess of 3 He in sediments referring to a probable loss of He from sediments before subduction by diffusion. Nitrogen in oceanic sediments and oceanic crust was analyzed by Sadofsky and Bebout (2004), Li and Bebout (2005), Li et al (2007) and Busigny et al (2005). The "Slab" component in Table 5 is presented as a mean composition with high N 2 /Ar, N 2 /He and a low 3 He/ 4 He.…”

“…Vulcano M corresponds to magmatic component in gases as defined byTaran (2011). The uncertainties (relative errors) are given very approximately, just to give an idea about the natural scatter of data.…”

Chapter 11 Geology, volcanic history and petrology of Vulcano (central Aeolian archipelago)

“…These characteristics combine to make Vulcano a key location for earth scientists to investigate the modifications of magma composition and eruption styles through time and their relationships with the structural and plumbing system evolution (De Astis et al 1997b;Del Moro et al 1998;Zanon et al 2003) or to improve understanding of the degassing processes and their geochemistry (e.g. Tamburello et al 2011;Taran 2011). The genesis of mantlederived arc magmas and their low-pressure evolution in crustal reservoirs were also other topics of interest offered by Vulcano products (Ellam & Harmon 1990;Gioncada et al 1998;De Astis et al 2000).…”