P-T-t estimation of syn-kinematic strain in low-grade quartz-feldspar bearing rocks using thermodynamic modeling and 40Ar/39Ar dating techniques: example of the Plan-de-Phasy shear zone unit (Briançonnais Zone, Western Alps)

Lanari, Pierre; Rolland, Y; Schwartz, S; Vidal, O; Guillot, S; Tricart, P; Dumont, T (2014). P-T-t estimation of syn-kinematic strain in low-grade quartz-feldspar bearing rocks using thermodynamic modeling and 40Ar/39Ar dating techniques: example of the Plan-de-Phasy shear zone unit (Briançonnais Zone, Western Alps). Terra nova, 26(2), pp. 130-138. Blackwell Scientific Publications 10.1111/ter.12079

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Pressure–Temperature–time (P–T–t) estimates of the syn-kinematic strain at the peak-pressure conditions reached during shallow underthrusting of the Briançonnais Zone in the Alpine subduction zone was made by thermodynamic modelling and 40Ar/39Ar dating in the Plan-de-Phasy unit (SE of the Pelvoux Massif, Western Alps). The dated phengite minerals crystallized syn-kinematically in a shear zone indicating top-to-the-N motion. By combining X-ray mapping with multi-equilibrium calculations, we estimate the phengite crystallization conditions at 270 ± 50 °C and 8.1 ± 2 kbar at an age of 45.9 ± 1.1 Ma. Combining this P–T–t estimate with data from the literature allows us to constrain the timing and geometry of Alpine continental subduction. We propose that the Briançonnais units were scalped on top of the slab during ongoing continental subduction and exhumed continuously until collision.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geological Sciences

UniBE Contributor:

Lanari, Pierre

Subjects:

500 Science > 550 Earth sciences & geology

ISSN:

0954-4879

Publisher:

Blackwell Scientific Publications

Language:

English

Submitter:

Pierre Lanari

Date Deposited:

29 Jul 2015 10:03

Last Modified:

14 Jul 2016 11:21

Publisher DOI:

10.1111/ter.12079

BORIS DOI:

10.7892/boris.70569

URI:

https://boris.unibe.ch/id/eprint/70569

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