Sediment travel paths in the Carboniferous as recorded by detrital zircon geochronology in the Dora-Maira and Zone Houillère

Paola Manzotti (1) , Michel Ballevre (2) , Marc Poujol (2)

1 Institute of Earth Sciences
2 GR - Géosciences Rennes

In the internal zone of the European Alps, late Carboniferous to Permian sediments have been detached from their basement (e.g. the Zone Houillère in the Briançonnais Zone). The Pinerolo Unit (Dora-Maira Massif) is the deepest unit exposed in the stack of the Western Alps and is considered to be Carboniferous in age based on lithological considerations (Franchi & Novarese, 1895; Argand, 1911). The blueschist-facies Pinerolo Unit occupies a key tectonic position in the Alpine belt, being overthrusted by the coesite-eclogite and quartz eclogite units of the Dora-Maira Massif. Detrital zircon grains from the Pinerolo Unit and the Zone Houillère (located along the external margin of the Briançonnais domain) display similar age patterns, with the youngest and largest population being Carboniferous (340-330 Ma). The distribution of Carboniferous magmatism in the Alps and surrounding areas suggests that the detritus was transported from Maures-Corsica and possibly from the Helvetic Zone into the Zone Houillère and the Pinerolo basin. Our results highlight the potential of detrital zircon geochronology for deciphering the sources of detrital material in meta-sediments, even if they have been affected by metamorphic overprints.

Domaines: Géochimie

Paola Manzotti, Michel Ballevre, Marc Poujol. Sediment travel paths in the Carboniferous as recorded by detrital zircon geochronology in the Dora-Maira and Zone Houillère. 14th Swiss Geoscience Meeting, Nov 2016, Genève, Switzerland. pp.20. ⟨insu-01450661⟩