Application of mineral and whole rock analysis in identification of petrogenesis of the pillow lavas in the Nain ophiolite

Pillow lavas are one of the important rock units of Nain ophiolite. Rock forming minerals of Nain ophiolite pillow lavas are chloritized olivine, plagioclase, clinopyroxene (augite), Cr-spinel, magnetite, amphibole, chlorite, pumpellyite, epidote, prehnite and calcite. Whole rock geochemical analyses and composition of clinopyroxenes and chromian spinels of these rocks indicate that they are similar to mid-ocean ridge basalts. These lavas are basalt to andesite in composition and produced by high degree of partial melting of a depleted mantle lherzolite. According to their field studies, petrography, mineral and whole rock geochemistry, they have undergone sub-sea floor metamorphism and changed to spilite. Application of clinopyroxene thermometry shows that they have formed at 1058 to 1170 OC.