A test of the cosmogenic 3 He production rate in the south-west Pacific (39°S)

Shaun R. Eaves, Gisela Winckler, Joerg M. Schaefer, Marcus J. Vandergoes, Brent V. Alloway, Andrew N. Mackintosh, Dougal B. Townsend, Matthew T. Ryan, Xun Li

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14 Citations (Scopus)

Abstract

Calculation of surface exposure ages, using in situ cosmogenic nuclides, requires accurate knowledge of local production rates. Here, we report the first attempt to calibrate cosmogenic 3 He production in the south-west Pacific region. We present a new radiocarbon chronology that precisely dates the emplacement of the Murimotu Formation, a large debris avalanche deposit in central North Island, New Zealand (ca. 830m asl; 39°S), which occurred 10.4-10.6cal ka BP. Measurements of cosmogenic 3 He in pyroxene separated from large andesitic blocks exposed during this event yield a sea-level high-latitude production rate of 120±12 atoms g -1 a -1 ('Lm' scaling). This is consistent with a recent global compilation, comprised predominantly of calibration sites located in the Northern Hemisphere. Thus, we conclude that the globally compiled cosmogenic 3 He production rate is valid in the south-west Pacific. Using independent, proximal calibrations of cosmogenic isotopes 10 Be and 14 C from quartz in New Zealand, we derive cosmogenic 3 He/ 10 Be and 3 He/ 14 C production ratios of 32.2±3.2 and 10.6±1.6, respectively.

Original languageEnglish
Pages (from-to)79-87
Number of pages9
JournalJournal of Quaternary Science
Volume30
Issue number1
DOIs
Publication statusPublished - 1 Jan 2015
Externally publishedYes

Keywords

  • Cosmogenic He
  • Debris avalanche
  • New Zealand
  • Pyroxene production rate calibration
  • Radiocarbon dating

Cite this

Eaves, S. R., Winckler, G., Schaefer, J. M., Vandergoes, M. J., Alloway, B. V., Mackintosh, A. N., Townsend, D. B., Ryan, M. T., & Li, X. (2015). A test of the cosmogenic 3 He production rate in the south-west Pacific (39°S). Journal of Quaternary Science, 30(1), 79-87. https://doi.org/10.1002/jqs.2760