A reevaluation of in situ cosmogenic 3He production rates Academic Article uri icon

abstract

  • He-3 is among the most commonly measured terrestrial cosmogenic nuclides, but an incomplete understanding of the He-3 production rate has limited robust interpretation of cosmogenic He-3 concentrations. We use new measurements of cosmogenic He-3 in olivine from a well-dated lava flow at Tabernacle Hill, Utah, USA, to calibrate the local He-3 production rate. The new He-3 measurements (n = 8) show excellent internal consistency and yield a sea level high latitude (SLHL) production rate of 123 +/- 4 at g(-1) yr(-1) following the Lal (1991)/Stone (2000) scaling model [Lal, D., 1991. Cosmic ray labeling of erosion surfaces: in situ nuclide production rates and erosion models. Earth and Planetary Science Letters, 104, 424-439.; Stone, J.O., 2000. Air pressure and cosmogenic isotope production. Journal of Geophysical Research, 105, 23753-23759.]. We incorporate the new measurements from Tabernacle Hill in a compilation of all published production rate determinations, characterizing the mean global SLHL production rates (e.g. 120 +/- 9.4 at g(-1) yr(-1) with Lal (1991)/Stone (2000)). The internal consistency of the global He-3 production rate dataset is as good as the other commonly used cosmogenic nuclides. Additionally, He-3 production rates in olivine and pyroxene agree within experimental error. The He-3 production rates are implemented in an age and erosion rate calculator, forming a new module of the CRONUS-Earth web-based calculator, a simple platform for cosmogenic nuclide data interpretation [Balco, G., Stone, J., Lifton, N.A., and Dunai, T.J., 2008. A complete and easily accessible means of calculating surface exposure ages or erosion rates from Be-10 and Al-26 measurements. Quaternary Geochronology, 3, 174-195.]. The He-3 calculator is available online at http://www.cronuscalculators.nmt.edu/. (C) 2010 Elsevier B.V. All rights reserved.

publication date

  • August 2010