Incorporating 3-D parent nuclide zonation for apatite ^4He/^3He thermochronometry: An example from the Appalachian Mountains
- Creators
- Fox, Matthew
- McKeon, Ryan E.
- Shuster, David L.
Abstract
The ability to constrain km-scale exhumation with apatite ^4He/^3He thermochronometry is well established and the technique has been applied to a range of tectonic and geomorphic problems. However, multiple sources of uncertainty in specific crystal characteristics limit the applicability of the method, especially when geologic problems require identifying small perturbations in a cooling path. Here we present new ^4He/^3He thermochronometric data from the Appalachian Mountains, which indicate significant parent nuclide zonation in an apatite crystal. Using LA-ICPMS measurements of U and Th in the same crystal, we design a 3-D model of the crystal to explore the effects of intra-crystal variability in radiation damage accumulation. We describe a numerical approach to solve the 3-D production-diffusion equation. Using our numerical model and a previously determined time temperature path for this part of the Appalachians, we find excellent agreement between predicted and observed ^4He/^3He spectra. Our results confirm this time-temperature path and highlight that for complex U and Th zonation patterns, 3-D numerical models are required to infer an accurate time-temperature history. In addition, our results provide independent and novel evidence for a radiation damage control on diffusivity. The ability to exploit intra-crystal differences in 4He diffusivity (i.e., temperature sensitivity) greatly increases the potential to infer complex thermal histories.
Additional Information
© 2014 American Geophysical Union. Received: Jun 18, 2014; Revised: Oct 07, 2014; Accepted: Oct 14, 2014. We thank P. Tackley for introducing M.F. to the multigrid approach and for sharing part of the code and A. Tripathy-Lang for comments on an early version of this manuscript. This work has been supported by the Swiss National Science Foundation (P2EZP2_148793), the U.S. National Science Foundation grant EAR-1049988 (to D.L.S.) and the Ann and Gordon Getty Foundation. In addition, R.E.M. acknowledges support from several Palmer Research grants from the Earth and Environmental Sciences Department of Lehigh University and to K. Farley at Caltech for help with [U] and [Th] LA-ICPMS analyses.Attached Files
Published - Fox_et_al-2014-Geochemistry,_Geophysics,_Geosystems.pdf
Files
Name | Size | Download all |
---|---|---|
md5:802b6f9b9427858ec0474a965fe83ff3
|
10.3 MB | Preview Download |
Additional details
- Alternative title
- Incorporating 3-D parent nuclide zonation for apatite 4He/3He thermochronometry: An example from the Appalachian Mountains
- Eprint ID
- 50829
- DOI
- 10.1002/2014GC005464
- Resolver ID
- CaltechAUTHORS:20141027-091019893
- P2EZP2_148793
- Swiss National Science Foundation (SNSF)
- EAR-1049988
- NSF
- Ann and Gordon Getty Foundation
- Palmer Research grants
- Lehigh University, Department of Earth and Environmental Sciences
- Caltech
- Created
-
2014-10-27Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field