(U-Th)/He thermochronometry: Mapping 3D geometry using micro-X-ray tomography and solving the associated production-diffusion equation
Détails
![Ressource 1](https://serval.unil.ch/static/img/forbidden.png)
Accès restreint UNIL
Etat: Public
Version: de l'auteur⸱e
ID Serval
serval:BIB_26FCD57E5FFD
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Institution
Titre
(U-Th)/He thermochronometry: Mapping 3D geometry using micro-X-ray tomography and solving the associated production-diffusion equation
Périodique
Chemical Geology
ISSN-L
0009-2541
Statut éditorial
Publié
Date de publication
2007
Peer-reviewed
Oui
Volume
242
Pages
126-136
Langue
anglais
Résumé
(U-Th)/He ages reflect the combined effects of He (a particles) loss due
to diffusion and He ingrowth due to radioactive decay of U and Th
series. Furthermore, the alpha particles are emitted with sufficient
kinetic energy that they can travel, in theory, up to 20 gm and as a
result, alpha particles may be ejected beyond the crystal edges. To
circumvent this problem a correction factor must be applied, which is
essentially based on the geometry of the crystals [Farley, K. A.,
Wolf, R., and Silver, L. (1996). The effect of long alpha-stopping
distances on (U-Th)/He dates. Geochimica et Cosmochimica Acta,
60:4223-4229]. This strongly limits the application of the technique to
crystals of appropriate geometries. We present here a method to compute
the effects of a-ejection for (U-Th)/He dating by taking into account
the 3D morphology of individual crystals determined with micro-X-ray
tomography. We also develop a model which solves the diffusion equation
for the crystals that have been imaged. We then couple this model with
an inversion algorithm to extract the range of thermal histories that
the rocks may have experienced. This technique is applied to detrital
samples from rocks collected in the Southern Alps of New Zealand, a
region of high exhumation rate. (C) 2007 Elsevier B.V. All rights
reserved.
to diffusion and He ingrowth due to radioactive decay of U and Th
series. Furthermore, the alpha particles are emitted with sufficient
kinetic energy that they can travel, in theory, up to 20 gm and as a
result, alpha particles may be ejected beyond the crystal edges. To
circumvent this problem a correction factor must be applied, which is
essentially based on the geometry of the crystals [Farley, K. A.,
Wolf, R., and Silver, L. (1996). The effect of long alpha-stopping
distances on (U-Th)/He dates. Geochimica et Cosmochimica Acta,
60:4223-4229]. This strongly limits the application of the technique to
crystals of appropriate geometries. We present here a method to compute
the effects of a-ejection for (U-Th)/He dating by taking into account
the 3D morphology of individual crystals determined with micro-X-ray
tomography. We also develop a model which solves the diffusion equation
for the crystals that have been imaged. We then couple this model with
an inversion algorithm to extract the range of thermal histories that
the rocks may have experienced. This technique is applied to detrital
samples from rocks collected in the Southern Alps of New Zealand, a
region of high exhumation rate. (C) 2007 Elsevier B.V. All rights
reserved.
Création de la notice
07/10/2012 20:46
Dernière modification de la notice
20/08/2019 14:05