Turkish Journal of Earth Sciences

Abstract: The Eastern Pontide Alkaline Volcanic Province is developed by volcanic cycles erupted in Cenozoic era. Petrographical and geochemical data suggest presence of at least two different suits of alkaline rocks (Tonya group and Trabzon group). Petrographically, both groups consist of alkali basalt, tephrite, phonolitic tephrite, basanite, nephelinite, nepheline latite and their pyroclastic rocks. Geochemically, Tonya samples have high MgO and Ni, low LREE contents and LILE/HFSE ratios compare to Trabzon group. Preliminary studies show that these two groups of rocks are related with low level differentiation and derived from a metasomatised mantle source.