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(D0) - of -4.71±0.94 (2σ)m2/s. These values imply a bulk closure temperature for 4He in Durango fluorapatite of 74°C for a 50μm radius grain, infinite cylinder geometry, and a cooling rate of 10°C/Myr.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 2409-2419 |
| Number of pages | 11 |
| Journal | Geochimica et Cosmochimica Acta |
| Volume | 75 |
| Issue number | 9 |
| DOIs | |
| State | Published - May 1 2011 |
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ASJC Scopus subject areas
- Geochemistry and Petrology
Cite this
Laser depth profiling studies of helium diffusion in Durango fluorapatite. / Van Soest, Matthijs; Monteleone, Brian D.; Hodges, Kip; Boyce, Jeremy W.
In: Geochimica et Cosmochimica Acta, Vol. 75, No. 9, 01.05.2011, p. 2409-2419.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Laser depth profiling studies of helium diffusion in Durango fluorapatite
AU - Van Soest, Matthijs
AU - Monteleone, Brian D.
AU - Hodges, Kip
AU - Boyce, Jeremy W.
PY - 2011/5/1
Y1 - 2011/5/1
N2 - 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(D0) - of -4.71±0.94 (2σ)m2/s. These values imply a bulk closure temperature for 4He in Durango fluorapatite of 74°C for a 50μm radius grain, infinite cylinder geometry, and a cooling rate of 10°C/Myr.
AB - 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(D0) - of -4.71±0.94 (2σ)m2/s. These values imply a bulk closure temperature for 4He in Durango fluorapatite of 74°C for a 50μm radius grain, infinite cylinder geometry, and a cooling rate of 10°C/Myr.
UR - http://www.scopus.com/inward/record.url?scp=79953204588&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=79953204588&partnerID=8YFLogxK
U2 - 10.1016/j.gca.2011.02.008
DO - 10.1016/j.gca.2011.02.008
M3 - Article
AN - SCOPUS:79953204588
VL - 75
SP - 2409
EP - 2419
JO - Geochmica et Cosmochimica Acta
JF - Geochmica et Cosmochimica Acta
SN - 0016-7037
IS - 9
ER -