Online exposure age calculator -- v. 2.2 -- alternate calibration data sets

Online exposure age calculator -- alternate calibration data sets Calculators home

This page links to input pages that calculate exposure ages using version 2.2 of the online exposure age calculator, but with published production rate calibration data sets that postdate and are different from the calibration data set used in the standard input page and described in Balco and others (2008) . These enable one to compute exposure ages using these alternate calibration data sets.

Note that there are small differences between the reference production rates quoted in the pages linked here and those quoted in the source papers. This is because, in these pages, best-fitting reference production rates have been recalculated using the same code that is used to compute exposure ages in the online calculator. This ensures an internally consistent application of calibration data to compute exposure ages. In other words, the source information being used here is the actual calibration data from the source papers, not the reference production rates derived from those data. More details about specific differences between as-published reference production rates and those used here appear in the input pages.

If you find apparent errors in exposure age calculations that are in excess of these differences, please let me know .

Note that reference production rates quoted in the pages linked here are for spallogenic production, not total production. Production rates due to muons are calculated as described in the documentation for version 2.2.

How to clearly describe what you did if you use these for published results: you should i) note that you used the method of calculating exposure ages described in Balco et al., 2008, but with a calibration data set from a different study; and ii) note the source of the calibration data set you used.

October, 2013. Questions on this page: Greg Balco, balcs@bgc.org

Northeast North America calibration data set

Reference: Balco, G., Briner, J., Finkel, R.C., Rayburn, J.A., Ridge, J.C., Schaefer, J.M., 2009, Regional beryllium-10 production rate calibration for northeastern North America. Quaternary Geochronology 4, pp. 93-107.

Links: input page calibration data set (text file)

You can repeat this calibration by entering these data in this page.

Macaulay River, New Zealand calibration data set

Reference: 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.

Links: input page calibration data set (Excel spreadsheet)

You can repeat this calibration by entering these data in this page.

Northern Norway rock avalanches calibration data set

Reference: 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.

Links: input page calibration data set (Excel spreadsheet)

You can repeat this calibration by entering these data in this page.

Lago Argentino, Patagonia calibration data set

Reference: Kaplan, M. and nine others, 2011. In-situ cosmogenic Be-10 production rate at Lago Argentino, Patagonia: implications for late-glacial climate chronology. Earth and Planetary Science Letters, v. 309, pp. 21-32.

Links: input page calibration data set (Excel spreadsheet)
These calibration data include sites that have minimum and maximum radiocarbon age constraints, rather than direct ages. Thus, best-fitting reference production rates are inferred from this data set using a "one-sided" optimization scheme that only penalizes the fit statistic when the minimum or maximum age constraints are violated. Here are links to MATLAB code that carries out this calculation:

wrap_P10_fit_Kaplan.m (wrapper script)

P10fit_minmax (objective function)

Kaplan_P10_data.txt (text file with calibration data)
In addition, you will need all the MATLAB code for version 2.2 of the exposure age calculator

Western Norway calibration data set

Reference: Goehring, B., and 6 others, 2012. Late Glacial and Holocene Be-10 production rates for western Norway. Journal of Quaternary Science, v. 27, pp. 89-96.

Links: input page calibration data set (Excel spreadsheet)

You can repeat this calibration by entering these data in this page.

Baffin Bay / Arctic calibration data set

Reference: 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.

Also, as far as I can tell, this includes data from and supersedes Briner et al., 2012, Constraining Holocene Be-10 production rates in Greenland. Journal of Quaternary Science, v. 27, pp. 2-6.

Links: input page calibration data set (Excel spreadsheet)

The Baffin Bay calibration data include some sites that have minimum and maximum radiocarbon age constraints, rather than direct ages. Thus, best-fitting reference production rates are inferred from this data set using a "one-sided" optimization scheme that only penalizes the fit statistic when the minimum or maximum age constraints are violated. Here are links to MATLAB code that carries out this calculation:

wrap_P10_fit_Arctic.m (wrapper script)

P10fit_minmax (objective function)

All_Arctic_P10_data.txt (text file with Arctic calibration data)
In addition, you will need all the MATLAB code for version 2.2 of the exposure age calculator

Huancane moraines/Quelccaya ice cap calibration data set

Reference: Kelly, M.A., Lowell, T.V., Applegate, P.J., Phillips, F.M., Schaefer, J.M., Smith, C.A., Kim, H., Leonard, K.C., Hudson, A.M., 2013. A locally calibrated, late glacial Be-10 production rate from a low-latitude, high-altitude site in the Peruvian Andes. Quaternary Geochronology.

Links: input page calibration data set (text file)

You can repeat this calibration by entering these data in this page.

Although the input page will perform exposure age calculations with the De, Du, and Lm scaling schemes, one should read this before using those scaling schemes to compute exposure ages. Also, note that production rate uncertainties are computed based on the internal reproducibility of samples at one site, and don't include any scaling uncertainty. There is more discussion of this issue here .

Tropical Andean volcano calibration data set

Reference: Blard, P.H., Braucher, R., Lavé, J., Bourlès, D., 2013. Cosmogenic Be-10 production rate calibrated against He-3 in the high Tropical Andes (3800–4900 m, 20–22° S). Earth and Planetary Science Letters, 382, 140-149.

Links: input page

Reference production rates used in this input page differ from the source paper, because they were recalculated to be internally consistent with the code used to calculate exposure ages. For details of the calculation, see here .

This input page will not perform exposure age calculations with the De, Du, and Lm scaling schemes. For details, see here. Also, note that production rate uncertainties are computed based on the internal reproducibility of samples at one site, and don't include any scaling uncertainty. There is more discussion of this issue here .

Compilation of 1989-2014 calibration data by Jakob Heyman.

Reference: Heyman, J., 2014. Paleoglaciation of the Tibetan Plateau and surrounding mountains based on exposure ages and ELA depression estimates.

This paper recompiles calibration data from Balco et al. (2008) and adds a large number of newer calibration data sets (many of which are represented on this page by themselves) to come up with a new global compilation.

The Heyman paper uses a site-weighted averaging scheme to come up with a summary production rate estimate. This is similar to what was done in the Balco et al. (2008) paper. Basically, he computes a best-fitting production rate for each site and then takes the average. Given the claim in this paper that the same forward age calculation code used in the online calculator was used for these production rate estimates (I did not attempt to replicate this calculation), one can use the production rate estimates given in Table 1 of the Heyman paper to compute exposure ages. The following links to an input page that does this:
Input page (published production rate estimates)

It is also possible to use the online calibration page to generate a production rate calibration from the calibration data as compiled by Heyman. To do this, enter the block of calibration data in this file (this is excerpted from the supplemental data file of the Heyman paper). As there are a lot of data, this calculation takes several minutes. The result will be:

Input page (replicate production rate estimates with different weighting scheme)

The key difference here is that although this should be using the same forward age calculation code as used by Heyman, it reflects different averaging assumptions: in this calculation, each site is weighted equally according to its uncertainty. This scheme yields slightly different results as the averaging scheme in the paper, but the two are indistinguishable given their uncertainties.


Online exposure age calculator -- alternate calibration data sets	Calculators home

This page links to input pages that calculate exposure ages using version 2.2 of the online exposure age calculator, but with published production rate calibration data sets that postdate and are different from the calibration data set used in the standard input page and described in Balco and others (2008) . These enable one to compute exposure ages using these alternate calibration data sets. Note that there are small differences between the reference production rates quoted in the pages linked here and those quoted in the source papers. This is because, in these pages, best-fitting reference production rates have been recalculated using the same code that is used to compute exposure ages in the online calculator. This ensures an internally consistent application of calibration data to compute exposure ages. In other words, the source information being used here is the actual calibration data from the source papers, not the reference production rates derived from those data. More details about specific differences between as-published reference production rates and those used here appear in the input pages. If you find apparent errors in exposure age calculations that are in excess of these differences, please let me know . Note that reference production rates quoted in the pages linked here are for spallogenic production, not total production. Production rates due to muons are calculated as described in the documentation for version 2.2. How to clearly describe what you did if you use these for published results: you should i) note that you used the method of calculating exposure ages described in Balco et al., 2008, but with a calibration data set from a different study; and ii) note the source of the calibration data set you used. October, 2013. Questions on this page: Greg Balco, balcs@bgc.org

Northeast North America calibration data set Reference: Balco, G., Briner, J., Finkel, R.C., Rayburn, J.A., Ridge, J.C., Schaefer, J.M., 2009, Regional beryllium-10 production rate calibration for northeastern North America. Quaternary Geochronology 4, pp. 93-107. Links: input page calibration data set (text file) You can repeat this calibration by entering these data in this page.

Macaulay River, New Zealand calibration data set Reference: 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. Links: input page calibration data set (Excel spreadsheet) You can repeat this calibration by entering these data in this page.

Northern Norway rock avalanches calibration data set Reference: 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. Links: input page calibration data set (Excel spreadsheet) You can repeat this calibration by entering these data in this page.

Lago Argentino, Patagonia calibration data set Reference: Kaplan, M. and nine others, 2011. In-situ cosmogenic Be-10 production rate at Lago Argentino, Patagonia: implications for late-glacial climate chronology. Earth and Planetary Science Letters, v. 309, pp. 21-32. Links: input page calibration data set (Excel spreadsheet) These calibration data include sites that have minimum and maximum radiocarbon age constraints, rather than direct ages. Thus, best-fitting reference production rates are inferred from this data set using a "one-sided" optimization scheme that only penalizes the fit statistic when the minimum or maximum age constraints are violated. Here are links to MATLAB code that carries out this calculation: wrap_P10_fit_Kaplan.m (wrapper script) P10fit_minmax (objective function) Kaplan_P10_data.txt (text file with calibration data) In addition, you will need all the MATLAB code for version 2.2 of the exposure age calculator

Western Norway calibration data set Reference: Goehring, B., and 6 others, 2012. Late Glacial and Holocene Be-10 production rates for western Norway. Journal of Quaternary Science, v. 27, pp. 89-96. Links: input page calibration data set (Excel spreadsheet) You can repeat this calibration by entering these data in this page.

Baffin Bay / Arctic calibration data set Reference: 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. Also, as far as I can tell, this includes data from and supersedes Briner et al., 2012, Constraining Holocene Be-10 production rates in Greenland. Journal of Quaternary Science, v. 27, pp. 2-6. Links: input page calibration data set (Excel spreadsheet) The Baffin Bay calibration data include some sites that have minimum and maximum radiocarbon age constraints, rather than direct ages. Thus, best-fitting reference production rates are inferred from this data set using a "one-sided" optimization scheme that only penalizes the fit statistic when the minimum or maximum age constraints are violated. Here are links to MATLAB code that carries out this calculation: wrap_P10_fit_Arctic.m (wrapper script) P10fit_minmax (objective function) All_Arctic_P10_data.txt (text file with Arctic calibration data) In addition, you will need all the MATLAB code for version 2.2 of the exposure age calculator

Huancane moraines/Quelccaya ice cap calibration data set Reference: Kelly, M.A., Lowell, T.V., Applegate, P.J., Phillips, F.M., Schaefer, J.M., Smith, C.A., Kim, H., Leonard, K.C., Hudson, A.M., 2013. A locally calibrated, late glacial Be-10 production rate from a low-latitude, high-altitude site in the Peruvian Andes. Quaternary Geochronology. Links: input page calibration data set (text file) You can repeat this calibration by entering these data in this page. Although the input page will perform exposure age calculations with the De, Du, and Lm scaling schemes, one should read this before using those scaling schemes to compute exposure ages. Also, note that production rate uncertainties are computed based on the internal reproducibility of samples at one site, and don't include any scaling uncertainty. There is more discussion of this issue here .

Tropical Andean volcano calibration data set Reference: Blard, P.H., Braucher, R., Lavé, J., Bourlès, D., 2013. Cosmogenic Be-10 production rate calibrated against He-3 in the high Tropical Andes (3800–4900 m, 20–22° S). Earth and Planetary Science Letters, 382, 140-149. Links: input page Reference production rates used in this input page differ from the source paper, because they were recalculated to be internally consistent with the code used to calculate exposure ages. For details of the calculation, see here . This input page will not perform exposure age calculations with the De, Du, and Lm scaling schemes. For details, see here. Also, note that production rate uncertainties are computed based on the internal reproducibility of samples at one site, and don't include any scaling uncertainty. There is more discussion of this issue here .

Compilation of 1989-2014 calibration data by Jakob Heyman. Reference: Heyman, J., 2014. Paleoglaciation of the Tibetan Plateau and surrounding mountains based on exposure ages and ELA depression estimates. This paper recompiles calibration data from Balco et al. (2008) and adds a large number of newer calibration data sets (many of which are represented on this page by themselves) to come up with a new global compilation. The Heyman paper uses a site-weighted averaging scheme to come up with a summary production rate estimate. This is similar to what was done in the Balco et al. (2008) paper. Basically, he computes a best-fitting production rate for each site and then takes the average. Given the claim in this paper that the same forward age calculation code used in the online calculator was used for these production rate estimates (I did not attempt to replicate this calculation), one can use the production rate estimates given in Table 1 of the Heyman paper to compute exposure ages. The following links to an input page that does this: Input page (published production rate estimates) It is also possible to use the online calibration page to generate a production rate calibration from the calibration data as compiled by Heyman. To do this, enter the block of calibration data in this file (this is excerpted from the supplemental data file of the Heyman paper). As there are a lot of data, this calculation takes several minutes. The result will be: Input page (replicate production rate estimates with different weighting scheme) The key difference here is that although this should be using the same forward age calculation code as used by Heyman, it reflects different averaging assumptions: in this calculation, each site is weighted equally according to its uncertainty. This scheme yields slightly different results as the averaging scheme in the paper, but the two are indistinguishable given their uncertainties.