The Nain ophiolitic massif, in the north of Nain town, consisted in lhezolitic-gabbroic (pegmatitic) bodies. Harzburgites, amphibolites, isotropic gab-bros, pillow lavas, gabbroic sills and dikes, pyroxenitic dikes, wherlitic dikes and gabbroic im-pregnations are also found. The crustal sequence is thin and is composed of limited volumes of pillow lavas and isotropic gabbros that gradually terminate into pelagic limestones and cherts in the upper levels. Amphibolites can be divided into garnet amphibolites with hornblende lineation, amphibolite mylonites with amphibole stretched lineation and non-foliated massive amphibolites. The other meta-morphosed units are spillites that include spillitized pillow lavas, diabases, isotropic gabbros and tuffites-tuffitic sandstones. Meta-gabbros associated with meta-peridotites and serpentinites are the abundant metamorphosed units of this massif. Pegmatitic gabbros are uplifted as melt mush in which the high plastically deformed clinopyroxenes can corroborate this hypothesis. Wherlitic dikes show shear or stress localization in the shear zones. The higher values of Cr and MgO# in isotropic gabbros than in basaltic rocks represent the equili-brium of gabbros with upper mantle peridotites. The clutter and fragmentation of this massif, also the thin crustal sequence, the volumetric serpentinites with intermingled exotic blocks of limestone, the heterogeneous plastic behavior of deformed minerals in mantle sequence and other factors demonstrate the derivation of this massif from the paleo-transform fault. We consider that this paleo-transform fault belongs to a slow spreading oceanic ridge.