Mineral Phases in the Edige Ophiolite Body

Abstract

Ediğe ophiolite body contains upper mantle and a part of crustal sequences, as a remnant of an oceanic lithosphere slice. The upper mantle sequence is composed of the primary assemblages of: olivin+ orthopyroxene + clinopyroxene + chromium spinel, in the tectonite ultramafics;and olivine + clinopyroxene + orthopyroxene in the cumulate ultramafics. The crustal sequence is characterized by the phases of: Plagioclase + clinopyroxene + olivin + orthopyroxene. Amphibole + serpentine + chlorite + prehnite + pumpellyite + sphene are the common secondary phases. The pyroxenes of the cumulate rocks are characterized by high Mg and very low contents of Na,K and Al. The plagioclase composition in the lovver level gabbros range from An40 to An90 The amount of amphibole development and albitization increase with stratigraphic height that, in the upper level gabbros the pyroxenes are almost completely replaced by amphibole and all the plagioclases are albite. Chromites of the tectonites are of podiform type. All the evidences suggest that the mineral assemblages in various rock types of the Ediğe ophiolite body are similar to the corresponding rocks of the oceanic lithosphere. Minerals of the cumulates suggest direct crystallization from spreading ridge magma. They have undergone metamorphic reconstitution correlated with ocean floor metamorphism.