In the mafic-ultramafic suite of Tazehkand, Kalaybar-NW Iran, of Early-Cenozoic age, pyroxenitic core is surrounded by gabbro and total complex is surrounded by Paleocene volcano clastic of Majid Abad Formation. The pyroxenite is composed chiefly of Cpx+Ol+Ore. The associated gabbro minerals consist of Pl + Cpx + Am + Phl. The pyroxene composition in the two rock types is diopside-rich and ranges between hedenbergite to Ca-tschermak. Plagioclase is anorthitic type and opaque mineral is mostly hematite. Some results of this investigation on the relationship between major phases activity and mineral chemical composition in these rocks are: Ca-tschermak activity in the pyroxenes is controlled with Al-content in T-site, Tschemakite activity in amphiboles has direct relation with ^(IV) Al, but reverse relations with ^(IV) Si, ^(VI) Al and ^(A) Na. Using several thermobarometric methods, temperature of 900 ºC for pyroxenites and pressure of 7-9 kbar on the same temperature for gabbro crystallization, are estimated. The temperature of observed ilmenite lamellae exsolution from hematite matrix during sub-solidus phenomena is detected about 470 ºC. Calculated Log fO₂ for the source magma is -8 to -14. This quantity is higher for pyroxenites than gabbros.