Spinel composition as a petrogenetic indicator of the mantle section in the Forumad ophiolite, NW Sabzevar, NE Iran

Forumad area is located in NW of Sabzevar, in NE of central Iran structural zone and in western part of Sabzevar ophiolite suite. The mantle section of Forumad ophiolite consists mainly of harzburgites, dunites, pyroxenitic dikes and choromititic lenses that contain brown to black Cr-spinels. The content of Cr2O3 and Al2O3 of Cr-spinels in harzburgites are between 32.6-53.1 and 15.6-34.8 wt%, respectively, and their Cr# ([100 × Cr/(Cr + Al]) atomic ratio]) is between 39- 69%. Relationship between Cr# of Cr-spinels and Fo of coexisting olivine (Fo=91-92%) and low contents of TiO2 (