Petrography, geochemistery and petrogenesis of Duzkoy (Trabzon) plutonic rocks

In this study, the petrography, petrology and geochemistry of the plutonic rocks in the southwest of Trabzon (Düzköy) have been investigated. The study area includes the districts of Derinoba Plateau, Ramazan Plateau, Komutan Plateau, Akise Plateau, Kalınçam, Keyifli, Kadırga and Çağmanlı settlements near Düzköy. The Düzköy plutonic rocks in granitic compositionare generally medium-coarse grained and gray-colored. These rocks contain quartz, plagioclase and alkali feldspar as main minerals. In addition, biotite, amphibole and opaque minerals are found in small amounts. In the rocks, sericitization, argillitization and carbonatization are observed as alteration types. The Düzköy plutonic rocks are subalkaline, low-K tholeiitic and high-K calc-alkaline, peraluminous and having S-type granite characteristics. The plutonic rock samples show enrichment in LIL elements and depletion in HFS elements in multiple trace element diagrams normalized to the primitive mantle. In the rare earth element diagrams normalized to condrite, enrichment in LRE elements and depletion in HRE elements were observed in these rock samples. In the tectonic differentiation diagrams, the rocks are located in the area of these volcanic arc granites (VAG). The molar major element-major element diagrams show that the main magmas of the Düzköy plutonic rocks are formed by the partial melting of metasedimantery rocks (metagreywacke). This is an important factor in the fractional crystallization in the origin of these plutonic rocks.