Résumé
The association of rocks with contrasting geodynamic affinities is a quite common feature in ophiolites and it has been documented in several ophiolitic complexes, such as Pindos (Greece), and Lycian and Antalya ophiolites (Turkey) (Saccani, Photiades 2004; Aldanmaz et al. 2009). New Caledonia hosts one of the World’s largest ultramafic terrane termed “Peridotite Nappe” belonging to an “atypical” ophiolitic sequence of presumed Late Cretaceous- Early Eocene age. It is dominated by mantle lithologies, mostly harzburgite and minor spinel and plagioclase lherzolite, together with some mafic and ultramafic cumulates. Despite their ultra-depleted nature, some efforts were devoted to characterize the mantle rocks from a geochemical point of view. A supra-subduction affinity is generally accepted for harzburgites (Marchesi et al. 2009; Ulrich et al. 2010); in contrast, the origin and evolution of lherzolites still remain a matter of debate. This presentation will focus on the petrological and geochemical characterization of the lherzolitic rocks.