Petrographical, geochemical and petrological characteristics of Eocene volcanic rocks in the Mescitli area, Eastern Pontides (NE Turkey)

Abstract

Mineralogical, petrographical and geochemical data are presented for the Eocene aged Mescitli volcanics in the Eastern Pontides (NE Turkey). The studied rocks are composed of basaltic andesitic, andesitic, basaltic trachyandesitic, trachyandesitic and minor dacitic and rhyolitic lavas associated with their pyroclastics. These rocks contain plagioclase, K-feldspar, quartz, hornblende, augite and biotite phenocrysts. They show calc-alkaline affinities and have medium to high-K contents. The volcanic rocks are enriched in large ion lithophile and light rare earth elements, with pronounced depletion of high field strength elements. The chondrite-normalized REE patterns (LaN/LuN=5-14) show low to medium enrichment, indicating similar sources for the rock suite. The main solidification processes involved in the evolution of the volcanics consist of fractional crystallization with minor amounts of crustal contamination ± magma mixing. All evidences support the conclusion that the parental magma(s) of the rocks probably derived from an enriched lithospheric mantle, which was previously modified by subduction induced metasomatism in a post-collisional geodynamic setting