https://ogma.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:14156 14C response, presumed to be related to site characteristics such as vegetation, temperature, rainfall, depth below the surface, and water pathway through the aquifer. Peak ¹⁴C activity for WM4 is 134.1 pMC, the highest cited thus far in the literature and suggestive of a lower inertia at this site. Dead carbon fractions for each stalagmite were calculated and found to be relatively similar for the 3 speleothems and lower than those derived from Northern Hemisphere speleothems. An inverse modeling technique based on the work of Genty and Massault (1999) was used to estimate soil carbon residence times. For each speleothem, mean soil 14C reservoir ages differed greatly between the 3 sites, ranging from 2–6.5 to 32–46 yr.]]> Wed 11 Apr 2018 16:39:29 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:2461 Wed 11 Apr 2018 16:34:23 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:2244 Wed 11 Apr 2018 15:28:12 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:26051 230Th relative even to the very low levels of detrital ²³⁰Th present. Here, we present an alternative method for reliable dating of these young speleothems using radiocarbon. Approximately 100 carbonate samples from SC4 and WM7 were analysed for ¹⁴C by accelerator mass spectrometry (AMS). The AMS results indicate that bomb ¹⁴C was evident in the youngest parts of both stalagmites. Two different approaches were used to estimate dead carbon fraction (DCF) values for these stalagmites for the pre-bomb period. For SC4, the DCF values were estimated based on the timing of ¹⁴C dates for that period determined by high-resolution δ¹⁸O recorded in the speleothem, and the timing of the onset of bomb ¹⁴C. For WM7, a “maximum” range of pre-bomb DCF was determined. Chronologies of these speleothems were built based on a dense sequence of DCF-corrected ages using three different age-depth models: Clam (Classical method), and Bacon and OxCal (Bayesian statistical approach). Good agreement between these age-depth models were observed indicating that the top 170 mm of SC4 and the top 50 mm of WM7 grew during the past 550–750 years and 1360–1740 years, respectively.]]> Sat 24 Mar 2018 07:31:29 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:3318 Sat 24 Mar 2018 07:23:17 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:3182 Sat 24 Mar 2018 07:18:09 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:3183 Sat 24 Mar 2018 07:18:09 AEDT ]]> https://ogma.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 ]]>