10Be - 26Al exposure age calculator
 For calculating an exposure age when erosion rate is known independently. Multiple sample form -- Putnam (2010) New Zealand calibration data. Uses version 2.2 code. October, 2013. Written by Greg Balco, balcs@u.washington.edu Calculators home

Notes:

Be-10 calibration data from:

Putnam, A.E. et al., 2010. In situ cosmogenic Be-10 production-rate calibration from the Southern Alps, New Zealand. Quaternary Geochronology 5, pp. 392.409.

Spreadsheet containing these data: Excel file

Small differences between reference production rates inferred from these data in the table below and in the source paper are the results of rounding errors and differences in the code used to do the calibration. For consistency, the reference production rates in the table below are calculated using the same code used to compute exposure ages.

Putnam and others didn't measure Al-26 concentrations. Reference production rates for Al-26 are calculated from those for Be-10 using (P26 / P10) = 6.75.

Editorial comment by Greg Balco: These calibration data are all from the same site and agree at measurement uncertainty, thus yielding a very small formal uncertainty in the inferred reference production rate. Because the data are all from the same site, this uncertainty does not include any scaling uncertainty. Thus, if you use this production rate calibration to compute exposure ages from a different site, you will underestimate the true external uncertainty of those exposure ages. Be aware of this when comparing exposure ages computed using this calibration data set between dispersed sites or between exposure-age and other chronologies.

 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 3.84 +/- 0.08 2.2 0.38 25.90 +/- 0.56 De 3.88 +/- 0.08 2.1 0.36 26.15 +/- 0.56 Du 3.86 +/- 0.08 2.1 0.37 26.07 +/- 0.55 Li 4.18 +/- 0.09 2.1 0.40 28.18 +/- 0.59 Lm 3.75 +/- 0.08 2.1 0.35 25.31 +/- 0.54

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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