Heterogeneous mantle sources feeding the volcanic activity of Mt. Karacadag (SE Turkey)

The volcanic activity of Mt. Karacadag (SE Anatolia) is divided into three major stages: Siverek Stage (similar to 11-2.7 Ma), Karacadag Stage (similar to 1.9-1.0 Ma) and Ovabag Stage (0.4-0.01 Ma). The magmas are mildly alkaline mafic rocks, mostly basanites, hawaiites and alkali basalts. Detailed geochemical investigation indicates a continuous variation of composition with time, with the oldest products (Siverek Stage) being characterized by average lowest HFSE (Ti, Hf, Zr, Nb, Ta), Nd-143/Nd-144, Nb/U, Ta/Yb, Nb/Nb* and the highest Delta Q, La/Nb, Ti/Nb, Zr/Nb, Ba/Nb, Th/Ta, K/La, and the youngest products (Ovabag Stage) at the opposite end of the trend. The overall incompatible element content of the Karacadag volcanic rocks resembles closely average HIMU-OIB compositions, with the oldest samples deviating more strongly from typical compositions of "anorogenic" magmas.