Late Pleistocene Tendürek Volcano (Eastern Anatolia, Turkey). II. Geochemistry and petrogenesis of the rocks

Abstract

The series of two papers presents a comprehensive isotope-geochronological and petrologicalgeochemical study of the Late Quaternary Tendürek 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 Tendürek 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 Tendürek Volcano during the whole period of its activity. The data obtained indicate that the igneous rocks of the Tendürek 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.