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

Italiano, F., Yuce, G., Uysal, I. T., Gasparon, M. and Morelli, G. (2014) Insights into mantle-type volatiles contribution from dissolved gases in artesian waters of the Great Artesian Basin, Australia. Chemical Geology, 378-379 1: 75-88. doi:10.1016/j.chemgeo.2014.04.013

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Author Italiano, F.
Yuce, G.
Uysal, I. T.
Gasparon, M.
Morelli, G.
Title Insights into mantle-type volatiles contribution from dissolved gases in artesian waters of the Great Artesian Basin, Australia
Journal name Chemical Geology   Check publisher's open access policy
ISSN 0009-2541
1872-6836
Publication date 2014-06-15
Year available 2014
Sub-type Article (original research)
DOI 10.1016/j.chemgeo.2014.04.013
Volume 378-379
Issue 1
Start page 75
End page 88
Total pages 14
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Language eng
Formatted 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/magma-derived fluids. The gases extracted from 19 water samples and analyzed for their chemical and isotopic composition exhibit amounts of CO2 up to about 340 mlSTP/LH2O marked by a δ13CTDC (Total Dissolved Carbon) ranging from − 16.9 to + 0.18‰ vs PDB, while CH4 concentrations vary from 4.4 × 10− 5 to 4.9 mlSTP/LH2O. Helium contents were between 9 and > 2800 times higher than equilibrium with Air Saturated Water (ASW), with a maximum value of 0.12 mlSTP/LH2O. Helium isotopic composition was in the 0.02–0.21 Ra range (Ra = air-normalized 3He/4He 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 original mantle contribution. Neotectonic activity involving deep lithospheric structures and magma intrusions, highlighted by recent geophysical investigations, is considered to be the drivers of mantle/magmatic volatiles towards the surface. The results, although pertaining to artesian waters from a vast area of > 542,000 km2, provide new constraints on volatile injection, and show that fluids' geochemistry can provide additional and independent information on the geo-tectonic settings of the Great Artesian Basin and its geothermal potential.
Keyword Dissolved gas geochemistry
Great Artesian Basin
Mantle
Fluids
Tectonic structures
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Earth Sciences Publications
School of Mechanical & Mining Engineering Publications
Official 2015 Collection
 
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