TRICART , Pierre

During the Neogene, the internal arc of the Western Alps underwent extension behind its inverted Paleogene frontal thrust while shortening affected the external arc. In the core of the internal arc, doming of eclogite-bearing gneissic nappes has formed the Dora–Maira massif. The blueschist-bearing Schistes lustrés of Queyras, which overlie the...

During the Oligocene, in the central western Alps, tectonic accretion of the external domain to the internal orogenic wedge along the Briançonnais Frontal Thrust (BFT) was followed by backfolding, resulting in the Alpine fanning structure. The Briançonnais fan axis was rapidly exhumed by erosion. This growing wedge at the scale of the entire...

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...

New fission-track ages on zircon and apatite (ZFT and AFT) from the southwestern alpine paleo-accretionary wedge document a contrasting cooling history from east to west. In the eclogitic Monviso ophiolites, the ZFT ages are 19.6 +/- 0.8 Ma and the AFT ages are 8.6 +/- 1.7 Ma. In the HT-blueschist eastern Queyras, ZFT ages range from 27.0 +/-...

his paper addresses the contribution of extension in the upper crust during syncollisional exhumation of subducted material. We present structural data based on the analysis of ductile, brittle-ductile, and brittle deformation features in metapelitic schists and meta-basalts from the Schistes lustrés nappe stack in the Piedmont zone of the...

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A geotransect from the Pelvoux Massif (external French Alps) to the Dora-Maira massif (internal Italian Alps), through the Monviso ophiolitic complex was investigated in the framework of a geological and geophysical imagery program of the continental crust: "Géo-France 3D Alpes". In this paper we present and discuss a new interpretative...