PETROLOGY AND PETROGENESIS OF ULTRAMAFIC ROCKS OF THE KHOY OPHIOLITIC COMPLEX-NW IRAN

Ultramafic rocks have extensive outcrops in the metamorphic complex of north of Khoy. Petrographically these rocks are: harzburgites, dunites and pyroxenites and are of both cumulate and tectonite types. Geochemically these rocks are two types. First type has U-shape REE pattern and with modeling of PUM batch melting, indicates rate of melt of 30-90% and with modeling of PUM Rayleigh melting, indicates 10-30% of partial melting of the upper mantle as source for these rocks. Second type has flat REE pattern and negative slope, probably indicating a metasomatized mantle. Modeling of PUM batch melting indicates rate of melt of 30-50% and with modeling of PUM Rayleigh melting indicates 10-20% for partial melting of the upper mantle.