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Jakob Heyman
A global compilation of glacial
10Be and 26Al exposure age data
Outline
Motivation The compilation Analysis
- Scatter / clustering
- Well-clustered ages
- 26Al / 10Be burial dating
- How many samples to collect?
A global compilation of glacial 10 Be and 26 Al exposure age data - - PowerPoint PPT Presentation
A global compilation of glacial 10 Be and 26 Al exposure age data - - PowerPoint PPT Presentation
A global compilation of glacial 10 Be and 26 Al exposure age data Jakob Heyman expage.github.io Outline Motivation The compilation Analysis - Scatter / clustering - Well-clustered ages - 26 Al / 10 Be burial dating - How many samples to
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Motivation 1
Enable easy recalculation of glacial exposure ages
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Motivation 2
Enable meta-analysis using a comprehensive dataset
Heyman et al. (2016)
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Included data
- 1. Primary publication
- 2. Sample type
- 3. Surface ID
- 4. Group ID
- 5. Sample name
- 6. Latitude
- 7. Longitude
- 8. Elevation
- 9. Sample thickness
- 10. Sample density
- 11. Shielding
- 12. 10Be concentration
- 13. 10Be uncertainty
- 14. 10Be standard
- 15. 26Al concentration
- 16. 26Al uncertainty
- 17. 26Al standard
- 18. Sampling year
- 19. Publ 10Be exp age
- 20. Publ 10Be exp age unc
- 21. Publ 26Al exp age
- 22. Publ 26Al exp age unc
- 23. Recalc 10Be exp age
- 24. 10Be external unc
- 25. 10Be internal unc
- 26. Recalc 26Al exp age
- 27. 26Al external unc
- 28. 26Al internal unc
- 29. Extra publication
Compilation work
- Searching Journals, Google Scholar, reference lists…
- Copy-paste, copy-paste, copy-paste…
- Correcting mistakes
- Emails
- Assumptions
- Recalculation
DATA COMMENTS
For recalculation Recalculated ages
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Lifton et al. (2014) Balco et al. (2008) Marrero et al. (2016) Phillips et al. (2016)
Recalculation
expage.github.io/calculator
Calibration studies 2009-2016
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10Be: 11 093 measurements 26Al : 1 683 measurements
Data from 527 primary publications
1815 bedrock samples 8399 boulder samples 940 cobble / pebbles / sediments samples 200 400 600 800 1000 1200 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Number of measurements Publication year Be-10 measurements Al-26 measurements
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Spatial distribution
Africa: 16 Asia: 2543 Antarctica: 1113 Europe: 2463 Greenland: 663 N America: 2205 S America: 1340 Oceania: 811
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All samples ordered in groups
Individual groups One group = one deglaciation age
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10 12 14 16 18 20 Exposure age (ka)
Well-clustered Well-clustered after
- utlier rejection
Scattered
Group exposure age clustering
Scattered: Chi-square analysis P-value < 0.05 Well-clustered: Chi-square analysis P-value > 0.05 Outlier rejection: max 1/3 still requiring at least 3 samples
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How common is well-clustered data?
10 20 30 40 50 60 70 80 Well-clustered groups (%) No outliers Outliers
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Clustering against mean age
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Clustering/scatter against mean age
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Clustering against mean age
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Well-clustered group ages
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Well-clustered group ages
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Forbidden zone: 6% Simple exposure: 47% Clear burial: 47%
ICE SHEETS
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Forbidden zone: 6% Simple exposure: 65% Clear burial: 29%
ALPINE
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How many samples per site?
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How many samples per publication?
5 10 15 20 25 30 35 20 40 60 80 100 Citations per year (Google Scholar 3-5 June 2016) Numer of samples
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expage.github.io
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