Browsing by Author "Schöning, G"

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    Strontium isotopes in the atmosphere, geosphere and hydrosphere: developing a systematic “fingerprinting” framework of rocks and water in sedimentary basins in eastern Australia
    (Elsevier, 2024-11-15) Raiber, M; Feitz, AJ; Cendón, DI; Flook, S; Suckow, A; Schöning, G; Hofmann, H; Martinez, J; Maas, R; Kelly, BFJ
    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.