Embracing the karst hydrological control on speleothem oxygen isotope variability

Simple item page
dc.contributor.authorTreble, PCen_AU
dc.contributor.authorBaker, AAen_AU
dc.contributor.authorPriestley, SCen_AU
dc.contributor.authorGriffiths, ADen_AU
dc.date.accessioned2023-11-08T03:54:29Zen_AU
dc.date.available2023-11-08T03:54:29Zen_AU
dc.date.issued2023-04-27en_AU
dc.date.statistics2023-08-21en_AU
dc.description.abstractThe influence of karst hydrology or ‘flowpaths’ on speleothem oxygen isotopic (δ18O) values has been simulated using karst forward models. Cave monitoring studies have also shown that variability in dripwater δ18O can be directly related to whether flowpaths are dominated by preferential/quick flow or diffuse/slow flow which challenges the paradigm of speleothems as archives of past variability in mean rainfall δ18O. Yet it is not known how common this flowpath effect is and whether it should be considered in the interpretation of speleothem δ18O records. Recently, Treble et al. (2022) analysed two global databases: SISAL v2 (Comas-Bru et al., 2020) and an extended compilation of dripwater from Baker et al. (2019). It was demonstrated that within-cave variability in mean δ18O values were common worldwide in both datasets. An analysis of cave meta-data demonstrated that the flowpath effect is unrelated to climate, cave depth or lithology; further supporting the ubiquitous nature of flowpaths, i.e., there is (1) a mixture of preferential and diffuse flow for all karstified carbonate rocks due to its triple-porosity nature (primary=matrix, secondary=fracture, tertiary=pipes and conduit); and (2) differences in soil/epikarst water storage and drainage characteristics. We demonstrate how a mechanistic understanding of flowpaths can lead to a more robust interpretation using a case study that is also relevant for managing water resources in the Mediterranean-type climate of south-west Australia. Using seven modern stalagmite records from four caves, plus dripwater data, we demonstrate that the cave δ18O record shows a common response to a sustained decrease in rainfall that impacted the region in the 1970s, characterised by a rise or ‘uptick’ in δ18O (Priestley et al., 2022). Mean annual rainfall δ18O values over the same period were quantified using observed and modelled data to have varied by −0.4 to +0.1 ‰ whereas the speleothem uptick is +1.5 ‰. The much larger magnitude of the uptick is consistent with a reduction in the preferential-flow component to these caves driven by reduced rainfall recharge. Preferential flow is an important contribution to groundwater. The ‘uptick’ or reduction in preferential flow implies that rainfall recharge to groundwater across the study region may no longer be reliably occurring. The longer paleo-record for south-west Australia confirms that no replicated upticks are seen in the last 800 years in stalagmites from the region and highlights the impact of climate change to water security in a region heavily dependent on groundwater. © Author(s) 2023. This work is distributed under the Creative Commons Attribution 4.0 License.en_AU
dc.identifier.articlenumberEGU23-2947en_AU
dc.identifier.citationTreble, P., Baker, A., Priestley, S., and Griffiths, A. (2023). Embracing the karst hydrological control on speleothem oxygen isotope variability. Paper presented at the EGU General Assembly 2023, Vienna, Austria and Online, 24–28 April 2023, EGU23-2947. doi:10.5194/egusphere-egu23-2947en_AU
dc.identifier.conferenceenddate2023-04-28en_AU
dc.identifier.conferencenameEGU General Assembly 2023en_AU
dc.identifier.conferenceplaceVienna, Austriaen_AU
dc.identifier.conferencestartdate2023-04-23en_AU
dc.identifier.urihttps://apo.ansto.gov.au/handle/10238/15175en_AU
dc.language.isoenen_AU
dc.publisherEuropean Geosciences Union (EGU)en_AU
dc.relation.urihttps://doi.org/10.5194/egusphere-egu23-2947en_AU
dc.subjectOxygen isotopesen_AU
dc.subjectCavesen_AU
dc.subjectGround wateren_AU
dc.subjectFlow rateen_AU
dc.subjectCarbonate rocksen_AU
dc.subjectPorosityen_AU
dc.subjectWestern Australiaen_AU
dc.subjectGroundwater rechargeen_AU
dc.titleEmbracing the karst hydrological control on speleothem oxygen isotope variabilityen_AU
dc.typeConference Presentationen_AU
Files
Original bundle
Now showing 1 - 2 of 2
Thumbnail Image
Name:
EGU23-2947_presentation.pdf
Size:
1.26 MB
Format:
Adobe Portable Document Format
Description:
Download
Thumbnail Image
Name:
EGU23-2947-print.pdf
Size:
311.84 KB
Format:
Adobe Portable Document Format
Description:
Download
License bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
license.txt
Size:
1.63 KB
Format:
Item-specific license agreed upon to submission
Description:
Download
Collections
Conference Publications