https://nova.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:49765 Wed 31 May 2023 09:27:40 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:52766 Mon 29 Jan 2024 18:40:13 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:43549 18O) variations in cave drip water as palaeorainfall proxies in an Australian alpine karst site. This paper presents the first extensive hydrochemical and δ¹⁸O dataset from Harrie Wood Cave, in the Snowy Mountains, south-eastern (SE) Australia. Using a 7-year long rainfall δ¹⁸O and drip-water Ca, Cl, Mg / Ca, Sr / Ca and δ¹⁸O datasets from three drip sites, we determined that the processes of mixing, dilution, flow path change, carbonate mineral dissolution and prior calcite precipitation (PCP) accounted for the observed variations in the drip-water geochemical composition. We identify that the three monitored drip sites are fed by fracture flow from a well-mixed epikarst storage reservoir, supplied by variable concentrations of dissolved ions from soil and bedrock dissolution. We constrained the influence of multiple processes and controls on drip-water composition in a region dominated by El Niño–Southern Oscillation (ENSO). During the El Niño and dry periods, enhanced PCP, a flow path change and dissolution due to increased soil CO₂ production occurred in response to warmer than average temperatures in contrast to the La Niña phase, where dilution dominated and reduced PCP were observed. We present a conceptual model, illustrating the key processes impacting the drip-water chemistry. We identified a robust relationship between ENSO and drip-water trace element concentrations and propose that variations in speleothem Mg / Ca and Sr / Ca ratios may be interpreted to reflect palaeorainfall conditions. These findings inform palaeorainfall reconstruction from speleothems regionally and provide a basis for palaeoclimate studies globally, in regions where there is intermittent recharge variability.]]> Fri 23 Sep 2022 08:55:26 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:40174 18O of two coeval modern speleothems from Cathedral Cave, Wellington, in semi-arid SE Australia are compared to the instrumental record to assess its efficacy as a proxy of past hydrological variability. Stalagmite δ¹⁸O was modulated by the frequency of recharge events and epikarst evaporation of storage water. Prolonged intervals between recharge events, such as droughts, resulted in higher stalagmite δ¹⁸O. Conversely, periods with more frequent recharge events and a positive water balance, resulted in lower δ¹⁸O. Disequilibrium cave processes are likely to be enhanced during dry conditions, although it is argued that these will modulate δ¹⁸O_spel in the same direction as epikarst evaporation, effectively amplifying the response of δ¹⁸O_spel. Extreme events, such as floods and droughts, were also captured in the stalagmite records, although potentially with a lag of several years. We verify that modern speleothems from semi-arid regions can be used to reconstruct hydroclimate due to variations in δ¹⁸O_spel modulated by karst processes. Such records are archives of past changes in recharge rather than precipitation amount or surface temperature, as is commonly applied to speleothem records from non-water-limited regions.]]> Fri 22 Jul 2022 13:55:20 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:49771 Fri 02 Jun 2023 17:37:40 AEST ]]>