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:36062 Wed 29 Jun 2022 16:31:10 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:44651 Wed 19 Oct 2022 09:56:34 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:7442 Wed 11 Apr 2018 10:58:09 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:14058 Wed 11 Apr 2018 09:29:33 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:17071 Wed 11 Apr 2018 09:19:38 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:50843 1200°C. Silicon and Al contents and Mg# of serpentinized spinel harzburgite, as well as heavy rare earth element modeling results, suggest a high-degree of melt extraction of 20–30% in the garnet stability field and in an anhydrous environment, probably in ocean island or oceanic plateau environments. The samples in this study have HSE concentrations interpreted to have resulted from post-melting processes rather than a melt extraction feature, indicating that their Re–Os model ages need to be interpreted with caution. Nevertheless, the melt depletion ages obtained from the Woodsreef and Port Macquaries samples range between 1.4 and 1.1 Ga, consistent with previous studies on other Pacific-rim ophiolitic rocks. We argue that these ages might be related to a major depletion event during the transition between supercontinents Nuna and Rodinia. Such depletion events affected a large proportion of this section of the mantle before the incorporation of the peridotites into the oceanic lithosphere in the Paleo-Pacific associated with rapid ascent of mantle plumes. This interpretation is consistent with the occurrence of accreted volcanic islands in the Weraerai ophiolite mélange, as shown by the OIB chemical signatures of some of the mafic rocks, and their association with shallow water limestones that formed in near-equatorial latitudes. The proposed c. 530–510 Ma Paleo-Pacific Ocean mantle plume event coincides with a global peak of oceanic mantle plume events that may record the legacy of a circum-Rodinia subduction girdle driving antipodal mantle superplume episodes.]]> Wed 09 Aug 2023 09:17:40 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:49055 Wed 03 May 2023 15:47:17 AEST ]]> https://nova.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://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:12071 Sat 24 Mar 2018 10:33:07 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:1534 Sat 24 Mar 2018 08:30:49 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:11476 Sat 24 Mar 2018 08:10:27 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:18102 Sat 24 Mar 2018 08:04:30 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:4999 Sat 24 Mar 2018 07:44:08 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:3346 25) Zr/Nb values. However, the Walli Volcanics are readily differentiated from the Cargo Volcanics by their higher P₂O₅ contents and likely high-K calc-alkaline to shoshonitic affinities. The Cargo Volcanics are intruded by Cu - Au mineralised, plagioclase + hornblende + quartz-phyric dacites with medium-K calc-alkaline affinities. These dacites have lower TiO₂ and higher MgO contents at any SiO₂ level compared to the Cargo Volcanics, and are compositionally similar to Late Ordovician to Early Silurian (453 - 441 Ma) dacites at Copper Hill and in the Narromine Complex. However, at Cargo, clasts derived from the dacites are locally abundant in volcaniclastic conglomerate near the top of the Cargo Volcanics, indicating that the dacites were intruded and exhumed prior to deposition of the Barrajin Group limestones, which commenced at ca 454 Ma in this area. The dacites at Cargo are intruded by small, apparently unmineralised monzonitic intrusions with shoshonitic affinities, which also appear to pre-date deposition of the Barrajin Group. LA-ICPMS U - Pb dating of detrital zircons from the Ranch Member at the base of the Daylesford Limestone (basal Barrajin Group) revealed a dominant population with an average age of 453.0 ± 4.1 Ma (identical within error to the mid-Ea1 age for the host sediments based on fossil assemblages) and subordinate populations with average ages of 480 Ma and 505 Ma. The 453 Ma zircons were most probably derived from either the intrusive dacites or monzonites, suggesting that the Cargo region was rapidly exhumed following emplacement of the felsic intrusions. The angular unconformities near and at the top of the Cargo Volcanics and the broadly coincident change in magma chemistry suggest that this sector of the Macquarie Arc underwent major tectonic upheaval commencing in the latest Gisbornian - early Eastonian. The Cargo Volcanics are interpreted to have undergone major eastward translation at this time (from an original position now buried beneath the Cowra Trough). Their present juxtaposition with the contiguous Molong Volcanic Belt probably did not occur until the late Early Silurian during the final stages of the Benambran Orogeny.]]> Sat 24 Mar 2018 07:18:34 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:3165 10 and Y, La and Nb values typical of tholeiitic magmas erupted in an island arc setting. By contrast, blueschists from this locality and from the Glenrock Station area show depleted REE patterns, Ti/V = 20–50, and eNd₄₈₀Ma = +8, features characteristic of normal mid-ocean ridge basalts (N-MORB). Meta-diorites from the Glenrock Station area have moderately depleted signatures (eNd₄₀₀Ma = +4.5) and Ti/V ratios and REE patterns typical of calc-alkaline and tholeiitic island arc magmas. These contrast with hornblende cumulate rocks from this location, which have very high Cr and Ni, low Zr and Y, and show slight LREE-enriched chondrite normalized patterns. Chromites (100 Cr/Cr+Al = 85) and clinopyroxenes (Wo₉₃En₄₂.₃Fs₇.₇ – Wo₄₈En₄₃.₇Fs₈.₃) in these rocks reveal an island arc affinity. The eNd₄₂₀Ma values vary from +2 to +4 and Rb–Sr ages from 425±177;44 Ma to 411±177;15 Ma. The core of a single grain of cumulus hornblende gave a poorly defined 40Ar/39Ar age of 394 Ma in contrast to younger ages (235–263 Ma) obtained from other grains. The younger ages are attributed to resetting of the K-Ar system during a metamorphic event. This study has provided further evidence for an Early Paleozoic arc-trench system along the eastern Gondwana margin.]]> Sat 24 Mar 2018 07:18:13 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:3169 Sat 24 Mar 2018 07:18:12 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:3168 Sat 24 Mar 2018 07:18:10 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:24545 Sat 24 Mar 2018 07:11:33 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:36781 Fri 03 Jul 2020 17:22:41 AEST ]]>