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Laser depth profiling studies of helium diffusion in Durango fluorapatite

van Soest, Matthijs C. and Monteleone, Brian D. and Hodges, Kip V. and Boyce, Jeremy W. (2011) Laser depth profiling studies of helium diffusion in Durango fluorapatite. Geochimica et Cosmochimica Acta, 75 (9). pp. 2409-2419. ISSN 0016-7037. https://resolver.caltech.edu/CaltechAUTHORS:20110902-111205800

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Abstract

Ultraviolet lasers coupled with sensitive mass spectrometers provide a useful way to measure laboratory-induced noble gas diffusion profiles in minerals, thus enabling the calculation of diffusion parameters. We illustrate this laser ablation depth profiling (LADP) technique for a previously well-studied mineral-isotopic system: ^4He in Durango fluorapatite. LADP studies were conducted on oriented, polished slabs from a single crystal that were heated under vacuum to a variety of temperatures between 300 and 450°C for variable times. The resolved ^4He profiles exhibited error-function loss as predicted by previous bulk ^4He diffusion studies. All of the slabs, regardless of crystallographic orientation, yielded modeled diffusivities that are statistically co-linear on an Arrhenius diagram, suggesting no diffusional anisotropy of ^4He in this material. The data indicate an activation energy of 142.2 ± 5.0 (2σ) kJ/mol and diffusivity at infinite temperature – reported as ln(D_0) – of −4.71 ± 0.94 (2σ) m^2/s. These values imply a bulk closure temperature for ^4He in Durango fluorapatite of 74°C for a 50 μm radius grain, infinite cylinder geometry, and a cooling rate of 10°C/Myr.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/j.gca.2011.02.008 DOIUNSPECIFIED
http://www.sciencedirect.com/science/article/pii/S0016703711000779PublisherUNSPECIFIED
Additional Information:© 2011 Elsevier Ltd. Received 13 October 2010; accepted in revised form 1 February 2011; available online 12 February 2011. The last stages of this work were partially supported by the U.S. National Science Foundation Petrology and Geochemistry program (EAR-0910983). We thank J.-A. Wartho for helpful discussions and suggestions, A. Tripathy for assistance in the laboratory and with the MATLAB coding, and D. Shuster, two anonymous reviewers and associate editor P. Reiners for their suggestions and thoughtful comments.
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Funding AgencyGrant Number
NSF Petrology and Geochemistry ProgramEAR-09110983
Issue or Number:9
Record Number:CaltechAUTHORS:20110902-111205800
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20110902-111205800
Official Citation:Matthijs C. van Soest, Brian D. Monteleone, Kip V. Hodges, Jeremy W. Boyce, Laser depth profiling studies of helium diffusion in Durango fluorapatite, Geochimica et Cosmochimica Acta, Volume 75, Issue 9, 1 May 2011, Pages 2409-2419, ISSN 0016-7037, DOI: 10.1016/j.gca.2011.02.008. (http://www.sciencedirect.com/science/article/pii/S0016703711000779)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:25210
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:02 Sep 2011 20:11
Last Modified:03 Oct 2019 03:04

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