Strontium isotopes in the atmosphere, geosphere and hydrosphere: developing a systematic “fingerprinting” framework of rocks and water in sedimentary basins in eastern Australia
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Date
2024-11-15
Journal Title
Journal ISSN
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Publisher
Elsevier
Abstract
Understanding the connection between aquifers, aquitards, and groundwater-dependant ecosystems remains a key challenge when developing a conceptual hydrogeological model. The aim of this study was to develop a systematic strontium isotope (87Sr/86Sr) fingerprinting framework of rocks and water within the sedimentary Surat and Clarence-Moreton basins (SCM basins) in eastern Australia – an area of extensive coal seam gas development and high potential for aquifer and groundwater-surface water connectivity. To do this, new groundwater samples (n = 298) were collected, analyzed and integrated with published data (n = 154) from the basins' major sedimentary, volcanic and alluvial aquifers, including the major coal seam gas target, the Walloon Coal Measures. Samples were also analyzed from rainfall (n = 2) and surface water (n = 40). In addition, rock core samples (n = 39) from exploration and stratigraphic wells were analyzed to determine the range of Sr isotope composition from host rocks. The analyses of cores demonstrate a distinct and systematic contrast in 87Sr/86Sr between different hydrogeological units. This confirms that all major hydrogeological units have a narrow range with unique 87Sr/86Sr population characteristics that are useful for guiding conceptual model development. Comparison with selected hydrochemical and groundwater age tracers (14C and 36Cl) suggests only limited changes of 87Sr/86Sr from recharge beds to the deeper parts of the basins or with a decrease in natural 14C and 36Cl tracer content along flow paths. Stream sampling during baseflow conditions confirms that 87Sr/86Sr in surface waters are similar to those of the underlying bedrock formations. We demonstrated that 87Sr/86Sr analyses of rocks and water provide a powerful hydrostratigraphic and chemostratigraphic fingerprinting framework in the SCM basins, enabling reliable assessments of plausible aquifer and groundwater-surface water interconnectivity pathways. Applied in other complex multi-aquifer sedimentary basins in Australia, and globally, a similar approach can help to constrain conceptual hydrogeological models and facilitate improved water resource management. © 2024 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY - NC 4.0 license.
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Keywords
Strontium isotopes, Aquifers, Ground water, Rocks, Sedimentary basins, Australia
Citation
Raiber, M., Feitz, A. J., Flook, S., Cendón, D. I., Suckow, A., Schöning, G., Hofmann, H., Martinez, J., Maas, R., & Kelly, B. F. J. (2024). Strontium isotopes in the atmosphere, geosphere and hydrosphere: developing a systematic “fingerprinting” framework of rocks and water in sedimentary basins in eastern Australia. Science of The Total Environment, 951, 175522. doi:10.1016/j.scitotenv.2024.175522