Insights into mantle-type volatiles contribution from dissolved gases in artesian waters of the Great Artesian Basin, Australia

Abstract

The geochemical features of the volatiles dissolved in artesian thermal waters discharged over three basins (Millungera, Galilee and Cooper basin) of the Australian Great Artesian Basin (GAB) consistently indicate the presence of fluids from multiple gas sources located in the crust (e.g. sediments, oil reservoirs, granites) as well as minor but detectable contributions of mantle/magmaderived fluids. The gases extracted from 19 water samples and analyzed for their chemical and isotopic composition exhibit amounts of CO 2 up to about 340 mlSTP/L H2O marked by a  13 C TDC (Total Dissolved Carbon) ranging from-16.9 to +0.18‰ vs PDB, while CH 4 concentrations vary from 4.4x10-5 to 4.9 mlSTP/L H2O. Helium contents were between 9 and >2800 times higher than equilibrium with Air Saturated Water (ASW), with a maximum value of 0.12 mlSTP/L H2O. Helium isotopic composition was in the 0.02-0.21Ra range (Ra = air-normalized 3 He/ 4 He ratio). The three investigated basins differ from each other in terms of both chemical composition and isotopic signatures of the dissolved gases whose origin is attributed to both mantle and crustal volatiles. Mantle He is present in the west-central and hottest part of the GAB despite no evidence of recent volcanism. We found that the partial pressure of helium, significantly higher in crustal fluids than in mantle-type volatiles, enhances the crustal He signature in the dissolved gases, thus masking the

Evidence of a shallow water submarine hydrothermal field off Zannone Island from morphological and geochemical characterization: Implications for Tyrrhenian Sea Quaternary volcanism

“…Details about the sampling and dissolved gas extraction methods are described in Italiano et al . [, ].…”

Geochemistry of dissolved gases from the Eastern Carpathians - Transylvanian Basin boundary

“…Chiodini et al 2004;Ray et al, 2009;Pinti et al, 2011;Barry et al, 2013;Italiano et al 2014;Marrero-Diaz et al 2015;Benavente et al 2016;Birke et al, 2016). Due to the geological variety of the Eastern Carpathians and Transylvanian Basin, wide range of volatiles can be produced which interact with the infiltrating water.…”

“…Recent studies show the role of dissolved gases in active tectonic settings, volcanic and non-volcanic areas (Sano et al, 1998(Sano et al, , 2004Hilton et al, 2002;Shaw et al, 2003;Chiodini et al 2004Chiodini et al , 2011Yang et al, 2005;De Leeuw et al, 2007;Italiano et al 2009Italiano et al , 2014Ray et al, 2009;Ohba et al, 2010;Pinti et al, 2011;Barry et al, 2013;Sano and Fischer, 2013;Marrero-Diaz et al 2015;Inguaggiato et al 2016;Benavente et al 2016;Birke et al, 2016;). Venting of highly mineralized (TDS>1000 mg/L) sparkling groundwater is a common feature along the Eastern Carpathians making the area an important water resource for Romania.…”

“…The water samples for dissolved gas analyses were stored in 240 cm 3 pyrex glass bottles and sealed in the field by silicon/teflon septa using special pliers following the indications and recommendations described in Capasso and Inguaggiato, (1998) and Italiano et al (2014). All the samples were collected taking care to avoid any air contamination (bottles sealed underwater with no direct contact with air) and kept upside down and with the neck submerged in salty water to avoid helium diffusion through the silicon septum.…”

“…The collected samples have been measured at the INGV Palermo geochemical laboratory (Italy), where analyses were carried out following the recommendations and limitations described in Italiano et al (2014). The dissolved gases were extracted after equilibrium was reached at constant temperature with a host-gas (high-purity argon) injected in the sample bottle (further details found in Italiano et al 2009Italiano et al , 2013.…”