Diachronous exhumation of HP-LT metamorphic rocks from southwestern Alps: evidence from fission-track analysis
Résumé
New fission-track ages on zircon and apatite (ZFT and AFT) from the southwestern alpine paleo-accretionary wedge document a contrasting cooling history from east to west. In the eclogitic Monviso ophiolites, the ZFT ages are 19.6 +/- 0.8 Ma and the AFT ages are 8.6 +/- 1.7 Ma. In the HT-blueschist eastern Queyras, ZFT ages range from 27.0 +/- 1.5 Ma to 21.7 +/- 1.6 Ma and AFT ages from 14.2 +/- 2.0 to 9.4 +/- 1.1 Ma. In the LT-blueschist western Queyras, ZFT ages are between 94.7 +/- 3.1 Ma and 63.1 +/- 2.9 Ma and AFT ages are between 22.2 +/- 1.6 and 22.6 +/- 1.5 Ma. The Chenaillet ophiolite yields ages of 118.1 +/- 3.7 Ma on ZFT and of 67.9 +/- 8.5 Ma on AFT. These new FT data combined with petrological and geochronological constraints record a diachronous exhumation in the paleo-accretionary wedge during subduction and collision.
Domaines
PétrographieOrigine | Fichiers produits par l'(les) auteur(s) |
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