Radiocarbon surface ocean reservoir ages over the past 6,000 years from Porites microatolls, Christmas (Kiritimati) Island, central Pacific Ocean

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dc.contributor.authorFink, Den_AU
dc.contributor.authorCarilli, JEen_AU
dc.contributor.authorMcGregor, HVen_AU
dc.contributor.authorWoodroffe, CDen_AU
dc.contributor.authorZhao, JXen_AU
dc.contributor.authorFallon, SJen_AU
dc.date.accessioned2023-02-17T05:14:52Zen_AU
dc.date.available2023-02-17T05:14:52Zen_AU
dc.date.issued2012-08-05en_AU
dc.date.statistics2022-01-28en_AU
dc.description.abstractWe present radiocarbon reservoir (ΔR) values over the past 5,000 years based on high-precision paired U-series and AMS 14C in modern and fossil Porites coral micro-atolls from Christmas Island (2N, 157W). The data set (n∼25) allows temporal reconstruction of ΔR with ∼250 year spacing. Christmas Island lies within the Equatorial Counter Current and the NINO3.4 region with a climate frequently punctuated by higher precipitation and warmer SSTs during El-Nino. Along its coastal perimeter, and throughout the internal network of tidal flats and lagoons, which in the late Holocene were flourishing reefal environments, fossil and modern microatolls abound. Microatolls are large discoid colonies with horizontal radial growth axes constrained in upwards vertical growth by spring tide low-water level. Consequently, a single microatoll can extend to ∼9 m in diameter representing an exceptional ∼300 years of continuous growth. Sr/Ca and δ18O in modern microatolls faithfully replicate instrumental climate records (SSTs, rainfall). Results from numerous fossil cores (1500–5500 years BP) shows distinct variability in ENSO variance both in frequency and amplitude domains compared to modern microatolls. These fossil populations are used to generate a temporal pattern of ΔR variability. Strict criteria were followed with respect to secondary calcite (via quantitative XRD), unaltered microstructure (via thin sections) and ensuring splits of identical coral chips for dual U-series and AMS 14C. Preliminary results show a ΔR decrease at about 2000 BP. Further analyses of correlations of ΔR deviations from the long term average with changes in regional ocean surface currents and in paleo-ENSO variance are in progress.en_AU
dc.identifier.citationFink, D., Carilli, J., McGregor, H, V., Woodroffe, C., Zhao, J.-x. & Fallon, S. (2012). Radiocarbon surface ocean reservoir ages over the past 6,000 years from Porites microatolls, Christmas (Kiritimati) Island, central Pacific Ocean. Paper presented to the 34th International Geological Congress 2012, "Unearthing our Past and Future - Resourcing Tomorrow", Brisbane, Australia, 5-10 August 2012. (pp. 3497).en_AU
dc.identifier.conferenceenddate10 August 2012en_AU
dc.identifier.conferencename34th International Geological Congress 2012, 'Unearthing our Past and Future - Resourcing Tomorrow'en_AU
dc.identifier.conferenceplaceBrisbane, Australiaen_AU
dc.identifier.conferencestartdate5 August 2012en_AU
dc.identifier.otherGC126268en_AU
dc.identifier.pagination3497en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/14657en_AU
dc.language.isoenen_AU
dc.publisherAustralian Geosciences Councilen_AU
dc.subjectCarbon 14en_AU
dc.subjectSeasen_AU
dc.subjectIslandsen_AU
dc.subjectPacific Oceanen_AU
dc.subjectFossilsen_AU
dc.subjectCoralsen_AU
dc.subjectDataen_AU
dc.subjectCoastal watersen_AU
dc.subjectClimatesen_AU
dc.subjectEnvironmenten_AU
dc.subjectMicrostructureen_AU
dc.subjectSouthern Oscillationen_AU
dc.titleRadiocarbon surface ocean reservoir ages over the past 6,000 years from Porites microatolls, Christmas (Kiritimati) Island, central Pacific Oceanen_AU
dc.typeConference Abstracten_AU
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