10Be - 26Al exposure age calculator
 For calculating an exposure age when erosion rate is known independently. Multiple sample form -- Young et al. (2013) Baffin Bay/Arctic calibration data set Uses version 2.2 code. October, 2013. Written by Greg Balco, balcs@u.washington.edu Calculators home

Notes:

Be-10 calibration data from:

Young N.E., Schaefer J.M., Briner J.P., Goehring B.M., 2013. A Be-10 production rate calibration for the Arctic. Journal of Quaternary Science, v. 28, pp. 515-526.

As discussed in the source paper, the reference production rates are inferred from calibration data from several sites around Baffin Bay, and production rate uncertainties include scaling uncertainty derived from other production rate calibration sites at high latitude in the Northern Hemisphere. Here these uncertainties are used. Thus, this reflects the "Arctic" reference production rates in Table 3b. The authors propose that these production rate estimates are applicable at the stated uncertainties for Holocene and late-glacial sites throughout the Arctic.

As discussed in the source paper, these production rates were estimated using a fitting algorithm that incorporates one-sided (i.e., minimum or maximum) radiocarbon age constraints. Thus, chi-squared fit values are not meaningful and not reported below. MATLAB code to do this calculation is available at the higher level page.

Small differences (< 1%) between the reference Be-10 production rates inferred from the calibration data in the table below and those reported in Table 3b in the source paper are due to differences in the code used to do the calculation and, to a lesser extent, rounding errors. To ensure consistency between production rate calibration and exposure-age calculations, the values in the table below are calculated using the same code that is used to compute the exposure ages in the online calculator.

Young et al. did not measure Al-26 concentrations. Thus, reference production rates for Al-26 in the table below are calculated from those for Be-10 using (P26 / P10) = 6.75.

 Scaling scheme Reference Be-10 Percentage Reduced Reference Al-26 for spallation production rate (atoms/g/yr) uncertainty chi-squared production rate (atoms/g/yr) St 3.93 +/- 0.15 3.8 - 26.55 +/- 1.01 De 4.10 +/- 0.17 4.2 - 27.65 +/- 1.15 Du 4.06 +/- 0.18 4.4 - 27.40 +/- 1.22 Li 4.35 +/- 0.19 4.4 - 29.36 +/- 1.28 Lm 3.93 +/- 0.15 3.8 - 26.55 +/- 1.01

Sample data entry:

Enter data block here.

Note change in Version 2.2:

Production rates and decay constants have been updated in this version to reflect the Be-10 restandardization and half-life revision in Nishiizumi et al., 2007. Thus, you must now specify the standard to which your Be-10 and Al-26 measurements have been normalized. This means that two input fields, the Be-10 and Al-26 standard names, have been added. You'll need to add two columns to your spreadsheets before cutting and pasting data. Refer to the new example spreadsheet here. For a list of currently available standards, see this page.

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