Découverte d'éclogites hercyniennes dans la chaı̂ne septentrionale des Mauritanides (Afrique de l'Ouest)

Abstract

Eclogites have been discovered within units constituting the prolongation of the Hercynian nappes of the Western Sahara (Northern Mauritanides). The eclogitic assemblage comprises Grt + Omp (Jd_30–40) + barroisite + Qtz + Rt ± phengite + Ep. Estimated pressure–temperature conditions are 550–600 °C, 13–15 kbar. Geochronological data obtained by the single evaporation method on zircons characterise a Panafrican event (595 Ma), which could be attributed to the magmatic crystallisation of the protolith. Sm–Nd dating by using garnet and omphacite argue for an Hercynian metamorphic event at 330 Ma.