Browsing by Author "Unal, E."

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Late Pleistocene Tendurek Volcano (Eastern Anatolia, Turkey). Ii. Geochemistry and Petrogenesis of the Rocks
(Pleiades Publishing inc, 2016) Lebedev, V. A.; Chugaev, A. V.; Unal, E.; Sharkov, E. V.; Keskin, M.
The series of two papers presents a comprehensive isotope-geochronological and petrologicalgeochemical study of the Late Quaternary Tendurek Volcano (Eastern Turkey), one of the greatest volcanoes within the Caucasian-Eastern Anatolian segment of the Alpine foldbelt. The second article discusses the results of petrogenetic modeling, role of AFC-processes in the petrogenesis of magmas and the nature of mantle source of the Tendurek Volcano. Based on geochronological data, geochemical and isotopegeochemical (Sr-Nd-Pb) characteristics of the studied rocks we suggest the petrological model which well describe the evolution of magmatic system of the Tendurek Volcano during the whole period of its activity. The data obtained indicate that the igneous rocks of the Tendurek Volcano belong to the same homodromous volcanic series (trachybasalt-tephrite-phonotephrite-tephriphonolite-trachyandesite-trachyte-phonolite), which are dominated by the intermediate and moderately-acid varieties of the eruption products. The leading role in the petrogenesis of the lavas was played by the fractional crystallization processes, which, according to isotope-geochemical data, were sometimes complicated by the assimilation of upper crustal material. The mantle reservoir responsible for the magmatic activity within the major part of the Eastern Anatolia in the Late Quaternary time was represented by the OIB-type mantle. It was subject to slight metasomatic changes as a result of earlier deepening and remelting of the Arabian Plate slab, which was subducted under the region through the end of the Miocene. The depth of the magma-generating source is estimated at around 80 km, which corresponds to the upper part of the asthenospheric wedge under the region, based on geophysical data.
Late Pleistocene Tendurek Volcano (Eastern Anatolia, Turkey): I. Geochronology and Petrographic Characteristics of Igneous Rocks
(Maik Nauka/interperiodica/springer, 2016) Lebedev, V. A.; Sharkov, E. V.; Unal, E.; Keskin, M.
The series of two papers presents a comprehensive isotope-geochronological and petrological-geochemical study of the Late Quaternary Tendurek Volcano (Eastern Turkey), one of the greatest volcanoes within the Caucasian-Eastern Anatolian segment of the Alpine foldbelt. The first article discusses the results of chronostratigraphic reconstruction and provides the main petrographic characteristics of the Tendurek's igneous rocks. The K-Ar dating results show that the magmatic activity of the Tendurek Volcano developed in the Late Pleistocene time, over the period of the last 250 thousand years. Five discrete phases (I-250-200 ka, II-200-150 ka, III-150-100 ka, IV-100-70 ka, and V-< 50 ka) of the youngest magmatism were identified in this study. The first two phases were represented by the fissure eruptions of alkaline basic lavas and subsequent formation of vast lava plateaus, the CaldA +/- ran and DogubeyazA +/- t plains. In the following phases, the intermediate and moderately-acid volcanic rocks of mildly-alkaline or alkaline series started to dominate among the eruption products. According to their petrographic characteristics, the rocks of Tendurek Volcano are assigned to the alkaline association with Na-specifics (hawaiites-mugearites-benmoreites). The available geological, isotope-geochronological, and geomorphological data suggest that the Tendurek Volcano is potentially active. Nowadays, Tendurek reaches the caldera stage of its development.