GEOCHEMISTRY OF VERCENIK MOUNTAIN (RIZE) GRANITOIDS IN EASTERN PONTIDE IGNEOUS TERRANE, TURKEY: CONSTRAINS ON I-TYPE, HYBRIDE MAGMATISM

Abstract

The outcropping granitoids in the Eastern Pontides, ranging from upper Cretaceous to Eocene in age, consisting of various intrusive rock units, have been defined as the composite Kackar Batholith. These rock units showing a high variety from granites through syenite and even to gabbros in composition are the plutonic equivalents of the Eastern Pontide Magmatism. This variety in both of the composition and age accompanies with a wide spectrum in genesis, from arc through collision and even to post-collisional within plate magmatism. The subunits of granitoids, The Ortakoy quartz monzonite, Kumlagolu monzogranite and Legenderesi micro granite, outcropping in the southern parts of the Kackar Batholith, the north of Vercenik Mountain, are the products of a K-rich calcalkaline, mostly metaluminous characterized, excessively continental crust contaminated, I-typed, and hybrid magma source's differentiation. According to some the HFSE, LILE and REE geochemistry data, such a single and hybrid magma is asserted to have a post-collisional genesis related to certain processes, like fractional crystallization and magma mixing. Late and post magmatic stages were dominated by strong hydrothermal activity. Granitoids of the studied area may be related to the igneous activity of the extensional regime in Eocene, after the collision of Anatolide - Pontide platforms, during a term of the well-known arc magmatism.