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Alpine orogenic evolution from subduction to collisional thermal overprint : the ⁴⁰Ar/³⁹Ar age constraints from the Valaisan Ocean, Central Alps

Wiederkehr, M. and Sudo, M. and Bousquet, R. and Berger, A. and Schmid, Stefan M.. (2009) Alpine orogenic evolution from subduction to collisional thermal overprint : the ⁴⁰Ar/³⁹Ar age constraints from the Valaisan Ocean, Central Alps. Tectonics, Vol. 28 (6). pp. 1-28.

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Abstract

The investigated HP/LT metasedimentary units of the Valaisan and adjacent European domains occupy a key position in the Alpine belt for understanding the transition from early subduction-related HP/LT metamorphism to collision-related Barrovian overprint and the evolution of mountain belts in general. The timing of high-pressure metamorphism, subsequent retrogression and following Barrow-type overprint was studied by 40Ar/39Ar dating of biotite and several white mica generations that are well characterized in terms of mineral chemistry, texture and associated mineral assemblages. Four distinct age populations of white mica record peak pressure conditions (42–40 Ma) and several stages of subsequent retrograde metamorphic evolution (36–25 Ma). Biotite isotopic analyses yield consistent apparent ages that cluster around 18–16 Ma for the Barrow-type thermal overprint. The recorded isotopic data reveal a significant time gap in the order of some 20 Ma between subduction-related HP/LT metamorphism and collision-related Barrovian overprint, supporting the notion of a polymetamorphic evolution associated with a bimodal P-T path.
Faculties and Departments:05 Faculty of Science > Departement Umweltwissenschaften > Geologie-Paläontologie > Tektonik (nn)
UniBasel Contributors:Schmid, Stefan M.
Item Type:Article, refereed
Article Subtype:Research Article
Bibsysno:Link to catalogue
Publisher:American Geophysical Union
ISSN:0278-7407
e-ISSN:1944-9194
Note:Publication type according to Uni Basel Research Database: Journal article
Language:English
Identification Number:
Last Modified:06 Nov 2017 14:04
Deposited On:22 Mar 2012 14:13

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