40Ar/39Ar dating of Penninic Front tectonic displacement (W Alps) during the Lower Oligocene (31-34 Ma)

Details

Serval ID
serval:BIB_175283DC094F
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
40Ar/39Ar dating of Penninic Front tectonic displacement (W Alps) during the Lower Oligocene (31-34 Ma)
Journal
Terra Nova
Author(s)
Simon-Labric T., Rolland Y., Dumont T., Heymes T., Authemayou C., Corsini M., Fornari M.
ISSN-L
0954-4879
Publication state
Published
Issued date
2009
Peer-reviewed
Oui
Volume
21
Pages
127-136
Language
english
Abstract
Direct absolute dating of the Penninic Frontal Thrust tectonic motion is
achieved using the Ar-40/Ar-39 technique in the Pelvoux Crystalline
Massif (Western Alps). The dated phengites were formed syn-kinematically
in shear zones. They underline the brittle-ductile stretching lineation,
pressure-shadow fibres and slickensides consistent with underthrusting
of the European continental slab below the propagating Penninic Thrust.
Chlorite-phengite thermobarometry yields 10-15 km and T similar to 280
degrees C, while Ar-40/Ar-39 phengite ages mainly range between 34 and
30 Ma, with one younger age at 27 Ma. This Early Oligocene age range
matches a major tectonic rearrangement of the Alpine chain. Preservation
of prograde Ar-40/Ar-39 ages is ascribed to passive exhumation of the
Pelvoux shear zone network, sandwiched between more external thrusts and
the Penninic Front reactivated as an E-dipping detachment fault. Partial
resetting in the Low Temperature part of argon spectra below 24 Ma is
ascribed to brittle deformation and alteration of phengites.
Create date
03/07/2013 20:43
Last modification date
20/08/2019 12:47
Usage data