https://nova.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:48378 Wed 15 Mar 2023 13:55:00 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:30180 2 drawdown during the last glacial period were linked to iron (Fe) fertilization of subantarctic surface waters. The principal source of this Fe is thought to be dust transported from southern mid-latitude deserts. However, uncertainty exists over contributions to CO₂ sequestration from complementary Fe sources, such as the Antarctic ice sheet, due to the difficulty of locating and interrogating suitable archives that have the potential to preserve such information. Here we present petrographic, geochemical and microbial DNA evidence preserved in precisely dated subglacial calcites from close to the East Antarctic Ice-Sheet margin, which together suggest that volcanically-induced drainage of Fe-rich waters during the Last Glacial Maximum could have reached the Southern Ocean. Our results support a significant contribution of Antarctic volcanism to subglacial transport and delivery of nutrients with implications on ocean productivity at peak glacial conditions.]]> Wed 11 Apr 2018 17:19:42 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:3370 Wed 11 Apr 2018 12:19:35 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:31155 Wed 11 Apr 2018 11:49:04 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:11218 Wed 11 Apr 2018 10:32:36 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:30186 14C ages ranged from 2232 to 2889 cal yr BP, with 95.4% probability age range in the youngest and oldest samples of 2153–2337 and 2342–3449 cal yr BP respectively. The median age of the more modern dripstone was 336 cal yr BP, with a 95.4% probability age range of 148–486 cal yr BP. These results provide very approximate ball-park estimates of the age of the sample, but are consistently too old when compared to the known maximum ages of formation. It is hypothesised that this offset is due to a combination of the nature of the organic carbon transported from the source organic matter pools, and reworking of both modern and old organic carbon by in situ microbial communities.]]> Wed 04 Sep 2019 09:39:24 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:1234 Sat 24 Mar 2018 08:28:33 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:1222 Sat 24 Mar 2018 08:28:30 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:30183 2 contribution to the total dissolved inorganic carbon (DIC). Pronounced millennial-scale shifts in DCP and relatively small coeval but antipathetic changes in δ¹³C are modulated by the effects of hydrological variability on open and closed-system dissolution, SAD and prior calcite precipitation. Hence, the DCP in Corchia Cave speleothems represents an additional proxy for rainfall amount.]]> Sat 24 Mar 2018 07:41:34 AEDT ]]> https://nova.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://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:25047 Sat 24 Mar 2018 07:10:46 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:35499 Mon 13 Mar 2023 15:06:27 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:47225 Fri 16 Dec 2022 10:37:32 AEDT ]]>