Petrograpy, petrochemistry and petrology of the tertiary aged Tekkeköy (Samsun) area volcanic rocks

In this study, petrographical, geochemical and petrological characteristics of Tertiary aged volcanic rocks in the Tekkeköy (Samsun) area were investigated, and the evolution and origin of the volcanics were evaluated. Based on facies features, Tertiary volcanic rocks in the study area at the western end of the Eastern Pontides are separated as agglomerate, trachyandesite dome and dykes, basalt and basaltic dykes. The volcanic rocks contain commonly plagioclase (An25-93), clinopyroxene (Wo27-52En31-46Fs11-26), hornblende (Mg#=0.50-0.65), biotite (Mg#=0.55-0.63), olivine (Fo49-68) and Fe-Ti oxides. The volcanics have medium ?high K and mildly alkaline characteristics. N-MORB normalized trace element patterns of the rocks are enriched in LILEs and depleted in HFSEs. Besides, the chondrite-normalized REE patterns show low to medium enrichment with concave shape, indicating significant hornblende and clinopyroxene fractionation. Initial 87Sr/86Sr and 143Nd/144Nd ratios are 0.704862-0.705282 and 0.512556-0.512630, respectively. Conclusively, Tekkeköy (Samsun) volcanic rocks evolved from parental magma (s) derived from an enriched lithospheric mantle source by subduction induced metazomatism, and exhibit general features of post-collisional volcanics in the Eastern Pontides.