M.Sc. Tezi Görüntüleme | |||||||||||||||||||||
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| Summary:
This study focuses on the petrographical, geological and petrological characteristics of the Eocene volcanics and dikes of unknown age exposing in the Trabzon-Tonya-Vakfıkebir region. In the study area which is situated in the northern part of the Eastern Pontide Magmatic Arc, The Eocene sequence starts with basaltic pillow lavas and grades upward agglomerates and tuffs. These rocks are cut by dikes of unknown age. Both Eocene volcanics and dikes show a microlithic porhyritic texture with mainly plagioclase and clinopyroxene (augite), and rarely olivine and leucite in fine-grained matrix. Calcite and zeolite occur as seconder phases in the rock. Eocene volcanics and dikes exhibit very similar geochemical characteristics. They are calc-alkaline in nature with low to medium K2O contents. On the Harker variation diagrams, Na2O, K2O and Al2O3 correlate positively with SiO2, while CaO and MgO display negative correlations. These trends suggest that fractional crystallization of mineral phases such as plagioclase, hornblende, Fe-Ti oxide and apatite played an important role in evolution of the studied rocks. However, some trace elements don’t show typical positive or negative correlations with SiO2. These unsystematic distributions imply that crustal contamination is very effective in evolution of the studied rocks. Chondrite and N-Type MORB-normalized trace and rare earth element patterns display typical negative Nb, Ta Zr and Ti anomalies.All these geochemical similarities between Eocene volcanics and dikes of unknown age support that these rocks were derived from same or similar mantle source in a post-collisional geotectonic setting. Key words: Eastern Pontide, Petrgraphy, Geochemistry, Petrology, Fractional crystallization, | |||||||||||||||||||||