Use of multi-isotope surveys to identify bedrock-alluvium interactions, Cressbrook Creek Catchment, southeast Queensland

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dc.contributor.authorKing, ACen_AU
dc.contributor.authorRaiber, Men_AU
dc.contributor.authorCendón, DIen_AU
dc.contributor.authorCox, MEen_AU
dc.date.accessioned2022-03-25T01:35:38Zen_AU
dc.date.available2022-03-25T01:35:38Zen_AU
dc.date.issued2013-09-19en_AU
dc.date.statistics2022-01-24en_AU
dc.description.abstractRadiocarbon (14C) is commonly used to study groundwater residence times, but the interpretation of results is often subject to a high degree of uncertainty due to interaction with modern and ‘dead carbon’, especially for relatively young groundwater or groundwater that has interacted with organic material. To address this concern, 87Sr/86Sr ratios, δ2H and δ18O, combined with tritium and radiocarbon are used to identify zones where older bedrock water recharges the alluvial aquifer of the Cressbrook Creek catchment in southeast Queensland. Cressbrook Creek is an intermittent stream that is primarily recharged by groundwater in the upper catchment. The alluvial system overlies variable bedrock with metamorphic rocks, rhyolites and granites in the headwaters, and sedimentary sequences (mostly sandstones) downstream. The catchment has largely been dry during a decade of drought, but has owed continuously since 2010 and experienced severe flooding in January 2011. Groundwater samples collected from alluvial and bedrock aquifers in June 2011 were analysed for a range of environmental tracers. Six alluvial waters were analysed for 14C; of these, four are modern. The other two samples have pMC values of 88.0 and 81.1 (uncorrected ages of 1,045 and 1,680 years; Sites A and B, respectively) whereas tritium analyses indicate an age of less than 100 years for the same samples. This disparity in groundwater ages may have been caused by: 1) seepage of older bedrock groundwater into the alluvium; or 2) carbonate dissolution processes. Therefore, evidence from other tracers, including 87Sr/86Sr, was assessed as an independent constraint to support the conceptual understanding of aquifer interactions. Alluvial groundwater from Site A has an enriched 87Sr/86Sr signature, indicating that it has probably received recharge from the underlying granite aquifer. Groundwater from Site B has a lower 87Sr/86Sr ratio than the other alluvial groundwaters, which indicates this site probably received recharge from the underlying sandstone aquifer.en_AU
dc.identifier.citationKing, A., Raiber, M., Cendón, D. & Cox, M. (2013). Use of multi-isotope surveys to identify bedrock-alluvium interactions, Cressbrook Creek Catchment, southeast Queensland. Paper presented to IAH 2013, Perth, Australia : "Solving the groundwater challenges of the 21st century", International Association of Hydrogeologists, 40th International Conference, Perth, Western Australia, 15-20 September 2013, (pp. 162).en_AU
dc.identifier.conferenceenddate20 September 2013en_AU
dc.identifier.conferencenameIAH 2013 Perth Australia : 'Solving the groundwater challenges of the 21st century', International Association of Hydrogeologists 40th International Conferenceen_AU
dc.identifier.conferenceplacePerth, Western Australiaen_AU
dc.identifier.conferencestartdate15 September 2013en_AU
dc.identifier.otherSession Three B, 255en_AU
dc.identifier.pagination162en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/12912en_AU
dc.language.isoenen_AU
dc.publisherInternational Association of Hydrogeologistsen_AU
dc.subjectCarbon 14en_AU
dc.subjectGround wateren_AU
dc.subjectCarbonen_AU
dc.subjectStrontium 87en_AU
dc.subjectStrontium isotopesen_AU
dc.subjectStable isotopesen_AU
dc.subjectOxygen isotopesen_AU
dc.subjectWatershedsen_AU
dc.subjectQueenslanden_AU
dc.subjectAustraliaen_AU
dc.subjectMetamorphic rocksen_AU
dc.subjectAquifersen_AU
dc.titleUse of multi-isotope surveys to identify bedrock-alluvium interactions, Cressbrook Creek Catchment, southeast Queenslanden_AU
dc.typeConference Abstracten_AU
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