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Les « Porphyro??des » de Bretagne méridionale : une unité de HP–BT dans la cha??ne hercynienneEvidence for HP–LT Hercynian metamorphism within the ‘Porphyro??des’ of South Brittany (France) |
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| Authors: | Florence Le Hébel Olivier Vidal Jean-Robert Kienast Denis Gapais |
| Institution: | 1. Géosciences Rennes, UMR 6118 CNRS, université Rennes-1, 35042 Rennes cedex, France;2. LGCA, université Joseph-Fourier–CNRS, BP 53, 38041 Grenoble cedex 9, France;3. Laboratoire de pétrologie métamorphique, URA 736 CNRS, Tour 26-0 E3, 4, place Jussieu, 75252 Paris cedex 05, France |
| Abstract: | The so-called ‘Porphyro??des’ Unit of South Brittany is located below units marked by an early HP–LT event (blueschists from the Île de Groix) and above units marked by Upper Carboniferous HT metamorphism. P–T estimates in the Porphyro??des (at Belle-Île-en-Mer), using the phengite–chlorite thermobarometer, indicate pressures around 8 kbar and temperatures of 350–400 °C. These new estimates suggest that the early tectonic history of the ‘Porphyro??des’ should be linked to that of the overlying Blueschists, and imply a much larger areal extension of the HP–LT domain in this part of the Hercynian Belt. To cite this article: F. Le Hébel et al., C. R. Geoscience 334 (2002) 205–211. |
| Keywords: | Hercynian Belt Armorican Massif high pressure–low temperature metamorphism phengite–chlorite thermobarometer France cha??ne hercynienne Massif armoricain métamorphisme de haute pression–basse température thermobaromètre phengite–chlorite France Tectonique Tectonics |
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