Pliocene to Qjiaternary miiginotism in the Karacadak -Volcanic Complex in SE Iiirkey occurred in the jo- reland region of the Arabia Eurasia collision and can be divided into two phases. The earlier Karacadag phase formed a north south-trending volcanic -ridge that erupted three groups of lavas. The same range of mantle sources contributed to the;younger Ovabag' phase lavas, which were erupted from monogenetic cones to the east of the Earacadag fissure. As at several other entrap/ate localities across the northern Arabian Plate this magmatism represents mixtures of melt from shallow, isotopically enriched ?nantle and from deeper, more depleted mantle. The deep source is similar to the depleted mantle invoked for other northern Arabian intraplate volcanic fields but at Karacadag (hie source contained phlogopite. This source could be located in the shallow convecting mantle or may represent a metasomatic layer in the base of the lithosphere. There is no evidence for a contribution from the Ajar mantle,plume, as has been proposed elsewhere in northern Arabia. Melting during the La' racadag and Ovabag phases could have resulted jr om a combination of upwelling beneath weak or ithosphere and restricted local extension of that weakened lithosphere as it collided with Eurasia. lens/on associated with the collision focused magma of the Karacadag phase into the elongate shield volcano of Mt. Karacadag'. 7 he northern end of the fissure accommodated more extensive differentiation of magma, with isolated cases of crustal contamination, consistent with greater stress in the lithosphere closest to the collision. Most magma batches of the Ka' racadag and Ovabag phases dWerentialed by fractional crystalat.4112a, near the boundary between the upper and lower crust. Alagma batches dominated by melt from garnet similar to 22.5MPa, which is close to the base of the lithospheric mantle.