Thermal structure of a fossil subduction wedge in the Western Alps

Terra Nova - Tập 21 Số 1 - Trang 28-34 - 2009
Sunsearé Gabalda1, Olivier Beyssac2, Laurent Jolivet3, Philippe Agard3, Christian Chopin2
1Ecole des Mines de Paris, Paristech, Géosciences, 77305 Fontainebleau, France
2Laboratoire de Géologie, Ecole Normale Supérieure, CNRS, 24 Rue Lhomond, 75005 Paris, France
3Laboratoire de Tectonique, Université Paris 6 ‐ CNRS, 4 place Jussieu, 75005, Paris, France

Tóm tắt

AbstractNew peak metamorphic temperatures are obtained by Raman spectroscopy of Carbonaceous Material to document the thermal structure of the central Western Alps with high sampling resolution. We show that peak metamorphic T gradually increases eastward from <330 to 350 °C (ultra‐Dauphinois to subbriançonnais units), ∼350 to more than 400 °C (Briançonnais domain including the Zone Houillère where metamorphic index minerals are rare) and from 350 to more than 500 °C (Liguro–Piemontese domain). Combined with other constraints on the metamorphic evolution, this dataset reveals a good preservation of the overall thermal structure of the fossil subduction wedge, with no particular thermal overprint during collision. However, local confrontation with P–T estimates and radiometric ages reveals more subtle variations within tectonic units and across the main contacts that are linked to the past activity of the major thrusts and extensional shear zones during subduction and exhumation.

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Terra Nova

Tập 21 Số 1

28-34

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