Rapid U-series dating of young fossil corals by laser ablation MC-ICPMS

Journal Article


Abstract


  • We demonstrate the utility of uranium-series age dating using laser ablation multi-collector inductively

    coupled plasma mass spectrometry (LA MC-ICPMS) to ‘range find’ a large suite of fossil corals in order to

    select those for subsequent detailed and high resolution paleoclimatological analyses. The high abundance

    of unaltered and long-lived (100e200 years) microatolls on Kiritimati Island, Kiribati, offers the

    exciting prospect of constructing a millennial, if not continuous, coral paleoclimate record for the central

    Pacific spanning the period from the mid-Holocene to present. However, with a multitude of collected

    corals and Kiritimati sample sites, we required an efficient, cost-effective and reliable analytical method

    to optimize selection of quality coral belonging to a prescribed age. Two modern and 41 fossil microatoll

    corals from Kiritimati were analysed by the range-finding LA MC-ICPMS technique with a subset also

    analysed by high-precision solution MC-ICPMS and AMS radiocarbon to assess the reliability and

    accuracy of the laser ablation technique. Coral ages ranged from 6400 to 900 yr BP and laser ablation age

    precisions, constrained by the low 230Th count rate, ranged from 9 to 45% at the 2SE level. These ages

    generally agreed with ages measured by solution U-series and AMS 14C. However, conflicting results for

    (234U/238U)initial in samples analysed by LA- and solution-MC-ICPMS indicates that the laser ablation

    method may not be as suitable as previously thought for detecting subtle geochemical alteration. With

    40e50 sample analyses per day, the laser ablation method offers a rapid, efficient and cost-effective

    means to histogram coral ages with multi-centennial accuracy, even at such low 230Th count rates typical

    for young Holocene samples. In addition to in situ corals, the LA MC-ICPMS technique could be further

    applied to corals recovered from drill core.

Publication Date


  • 2011

Citation


  • McGregor, H. V., Hellstrom, J. C., Fink, D., Hua, Q. & Woodroffe, C. D. (2011). Rapid U-series dating of young fossil corals by laser ablation MC-ICPMS. Quaternary Geochronology, 6 (2), 195-206.

Scopus Eid


  • 2-s2.0-79952072268

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/5251

Has Global Citation Frequency


Number Of Pages


  • 11

Start Page


  • 195

End Page


  • 206

Volume


  • 6

Issue


  • 2

Abstract


  • We demonstrate the utility of uranium-series age dating using laser ablation multi-collector inductively

    coupled plasma mass spectrometry (LA MC-ICPMS) to ‘range find’ a large suite of fossil corals in order to

    select those for subsequent detailed and high resolution paleoclimatological analyses. The high abundance

    of unaltered and long-lived (100e200 years) microatolls on Kiritimati Island, Kiribati, offers the

    exciting prospect of constructing a millennial, if not continuous, coral paleoclimate record for the central

    Pacific spanning the period from the mid-Holocene to present. However, with a multitude of collected

    corals and Kiritimati sample sites, we required an efficient, cost-effective and reliable analytical method

    to optimize selection of quality coral belonging to a prescribed age. Two modern and 41 fossil microatoll

    corals from Kiritimati were analysed by the range-finding LA MC-ICPMS technique with a subset also

    analysed by high-precision solution MC-ICPMS and AMS radiocarbon to assess the reliability and

    accuracy of the laser ablation technique. Coral ages ranged from 6400 to 900 yr BP and laser ablation age

    precisions, constrained by the low 230Th count rate, ranged from 9 to 45% at the 2SE level. These ages

    generally agreed with ages measured by solution U-series and AMS 14C. However, conflicting results for

    (234U/238U)initial in samples analysed by LA- and solution-MC-ICPMS indicates that the laser ablation

    method may not be as suitable as previously thought for detecting subtle geochemical alteration. With

    40e50 sample analyses per day, the laser ablation method offers a rapid, efficient and cost-effective

    means to histogram coral ages with multi-centennial accuracy, even at such low 230Th count rates typical

    for young Holocene samples. In addition to in situ corals, the LA MC-ICPMS technique could be further

    applied to corals recovered from drill core.

Publication Date


  • 2011

Citation


  • McGregor, H. V., Hellstrom, J. C., Fink, D., Hua, Q. & Woodroffe, C. D. (2011). Rapid U-series dating of young fossil corals by laser ablation MC-ICPMS. Quaternary Geochronology, 6 (2), 195-206.

Scopus Eid


  • 2-s2.0-79952072268

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/5251

Has Global Citation Frequency


Number Of Pages


  • 11

Start Page


  • 195

End Page


  • 206

Volume


  • 6

Issue


  • 2