Transcript New Production Rate Estimates for In Situ Cosmogenic 14 C

New Production Rate Estimates for
In Situ Cosmogenic 14C
Bailey Dugan, Nathaniel Lifton, A.J. Timothy Jull
University of Arizona
Cronus-Earth/EU Workshop, Vancouver, July 12-13 2008
Funded By The U.S. National Science Foundation
Promontory Point Results
 Site Production Rates
Generally Consistent
w/Earlier Estimates
49.7 ± 1.3 w/05PPT-02
51.4 ± 0.8 w/o 05PPT-02
 Replicates
 Unexplained Variability
 Use Weighted Means
 05PPT-02
 Replicates Agree
 >2 Below Site Weighted
Mean
 No Obvious Reason
 Higher Position on
05PPT-01 Outcrop
 Excluded from Further
Analysis
CRONUS-Earth
 Additional Analyses
Planned
Corrie Nan Arr Results
 Good Agreement
Between Supra- and
Sub-Glacial Boulders
 Supports Assumption of
Landslide Deposition on
Retreating Glacier
 Additional Analyses
Planned
CRONUS-Earth
Maol Chean-Dearg (Mull Kin Jerig) Results
 Site Production Rates
Show Generally Good
Agreement
 Replicates
 Unexplained Variability
 Use Weighted Means
 Additional Analyses
Planned
CRONUS-Earth
Sea Level, High Latitude (SLHL)
Production
 Four Scaling Models Compared
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Lal (1991)/Stone(2000)
Dunai (2001)
Desilets & Zreda (2003)/Desilets et al. (2006)
Lifton et al. (2005)
 Variable Atmosphere Assumed for All
 Geomagnetic Assumptions
 Geocentric Axial Dipole for Lal/Stone
 Continuous Geomagnetic Model of Lifton et al. (2008) for Others
CRONUS-Earth
Scale to SLHL