A reevaluation of in situ cosmogenic ³He production rates

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• 作者：Brent M. Goehring ; Mark D. Kurz ; Greg Balco ; Joerg M. Schaefer ; Joseph Licciardi ; Nathaniel Lifton
• 关键词：Helium-3 ; Cosmogenic nuclide ; Exposure dating ; Erosion rate
• 刊名：Quaternary Geochronology
• 出版年：2010
• 出版时间：August 2010
• 年：2010
• 卷：5
• 期：4
• 页码：410-418
• 全文大小：1255 K

文摘

³He is among the most commonly measured terrestrial cosmogenic nuclides, but an incomplete understanding of the ³He production rate has limited robust interpretation of cosmogenic ³He concentrations. We use new measurements of cosmogenic ³He in olivine from a well-dated lava flow at Tabernacle Hill, Utah, USA, to calibrate the local ³He production rate. The new ³He 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 ³He production rate dataset is as good as the other commonly used cosmogenic nuclides. Additionally, ³He production rates in olivine and pyroxene agree within experimental error. The ³He 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 ¹⁰Be and ²⁶Al measurements. Quaternary Geochronology, 3, 174–195.]. The ³He calculator is available online at http://www.cronuscalculators.nmt.edu/.