https://ogma.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:49765 Wed 31 May 2023 09:27:40 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:46693 Tue 29 Nov 2022 09:42:29 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:30179 18O and δ¹³C minima. Periods of lowered recharge are indicated by ¹⁸O and δ¹³ enrichment, primarily affecting δ¹⁸O, argued to be driven by evaporation of shallow soil/epikarst water in this water-limited environment. A hydrological driver is supported by calcite fabric changes. These include the presence of laminae, visible organic colloids, and occasional dissolution features, related to recharge, as well as the presence of sediment bands representing cave floor flooding. A shift to slower-growing, more compact calcite and an absence of lamination is interpreted to represent reduced recharge. The Mairs Cave record indicates that the Flinders Ranges were relatively wet during the LGM and early deglaciation, particularly over the interval 18.9–15.8 ka. This wetter phase ended abruptly with a shift to drier conditions at 15.8 ka. These findings are in agreement with the geomorphic archives for this region, as well as the timing of events in records from the broader Australasian region. The recharge phases identified in the Mairs Cave record are correlated with, but antiphase to, the position of the westerly winds interpreted from marine core MD03-2611, located 550 km south of Mairs Cave in the Murray Canyons region. The implication is that the mid-latitude westerlies are located further south during the period of enhanced recharge in the Mairs Cave record (18.9–16 ka) and conversely are located further north when greater aridity is interpreted in the speleothem record. A further comparison with speleothem records from the northern Australasian region reveals that the availability of tropical moisture is the most likely explanation driving enhanced recharge, with further amplification of recharge occurring during the early half of Heinrich Stadial 1 (HS1), possibly influenced by a more southerly displaced Intertropical Convergence Zone (ITCZ). A rapid transition to aridity at 15.8 ka is consistent with a retraction of this tropical moisture source.]]> Tue 20 Aug 2024 11:05:18 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:37522 230Th content. This poses problems in establishing reliable trends and periodicities for droughts and pluvial episodes in a region vulnerable to climate change. Here we constrain the chronology of a Cook Islands stalagmite using synchrotron µXRF two-dimensional mapping of Sr concentrations coupled with growth laminae optical imaging constrained by in situ monitoring. Unidimensional LA-ICP-MS-generated Mg, Sr, Ba and Na variability series were anchored to the 2D Sr and optical maps. The annual hydrological significance of Mg, Sr, Ba and Na was tested by principal component analysis, which revealed that Mg and Na are related to dry-season, wind-transported marine aerosols, similar to the host-rock derived Sr and Ba signatures. Trace element annual banding was then used to generate a calendar-year master chronology with a dating uncertainty maximum of ± 15 years over 336 years. Our approach demonstrates that accurate chronologies and coupled hydroclimate proxies can be obtained from speleothems formed in tropical settings where low seasonality and problematic U–Th dating would discourage the use of high-resolution climate proxies datasets.]]> Tue 15 Nov 2022 14:35:44 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:54914 Thu 21 Mar 2024 12:03:59 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:49220 Sun 07 May 2023 09:37:55 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:1524 Sat 24 Mar 2018 08:30:48 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:1701 0 °C at a time when MIS 6 ice volumes were close to their maximum. High stable carbon isotope (δ¹³C) values (−2.8‰ to +3.1‰) throughout the stalagmite's growth reflect a persistently low input of biogenic CO², indicating that the steep, barren and alpine-like recharge area of today has been in existence for at least the last ∼380 kyr. During MIS 9, the lowest δ¹³C values occur well after maximum interglacial conditions, suggesting a lag in the development of post-glacial soils in this high-altitude karst. The stable oxygen isotope (δ¹⁸O) trends match the main structural features of the major climate proxy records (SPECMAP, Vostok and Devils Hole), suggesting that the δ¹⁸O of CC1 has responded to global-scale climate changes, whilst remarkable similarity exists between CC1 δ¹⁸O and regional sea-surface temperature reconstructions from North Atlantic core ODP980 and southwest Pacific marine core MD97-2120 through the most detailed part of the CC1 record, MIS 9–8. The results suggest that CC1 and other stalagmites from the cave have the potential to capture a long record of regional temperature trends, particularly in regards to the relative severity of Pleistocene glacial stages.]]> Sat 24 Mar 2018 08:27:20 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:9790 Sat 24 Mar 2018 08:11:04 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:9792 Sat 24 Mar 2018 08:11:03 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:28922 Homo neanderthalensis, with some phenetic peculiarities that appear consistent with a chronology ranging from 172 ± 15 ka to 130.1 ± 1.9 ka. Thus, the skeleton from Altamura represents the most ancient Neanderthal from which endogenous DNA has ever been extracted.]]> Sat 24 Mar 2018 07:31:24 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:3183 Sat 24 Mar 2018 07:18:09 AEDT ]]>