10Be - 26Al exposure age calculator

For calculating an exposure age when erosion rate is known independently.

Multiple sample form -- Fenton et al. (2010) Norway rock avalanche calibration data set

Uses version 2.2 code. October, 2013.

Written by Greg Balco, balcs@u.washington.edu

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Be-10 calibration data from:
Fenton, C. and 7 others, 2011. Regional Be-10 production rate calibration for the past 12 ka deduced from the radiocarbon-dated Grøtlandura and Russenes rock avalanches at 69° N, Norway. Quaternary Geochronology 6, pp. 437-452.

Calibration data: Excel spreadsheet

Differences between the reference Be-10 production rates inferred from the calibration data in the table below and those reported 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. In this example, the main difference appears to be the use of a different elevation-atmospheric pressure relationship here and in the source paper.

Fenton et al. didn't 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.

Editorial comment by Greg Balco: There appears to be a small inconsistency in the source paper in that the authors appear to state that Be-10 concentrations are normalized to the Chmeleff/Korschinek half-life determination (p. 445, top second column) and also that they are normalized to the revised (2010) value of the S555 standard (Table 4 notes). Although consistent at measurement uncertainty, these aren't actually exactly the same thing. This is a percent-level effect.

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)


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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