Browsing by Author "Chugaev, A. V."

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The Geochronology and Origin of Mantle Sources for Late Cenozoic Intraplate Volcanism in the Frontal Part of the Arabian Plate in the Karacadag Neovolcanic Area of Turkey. Part 1. The Results of Isotope-Geochronological Studies
(Pleiades Publishing inc, 2012) Keskin, M.; Chugaev, A. V.; Lebedev, V. A.; Sharkov, E. V.; Oyan, V.; Kavak, O.
This paper considers results from isotope-geochronological (K-Ar) studies of the products of Neogene-Quaternary volcanism in the Karacadag area, which is situated within the northern frontal part of the Arabian plate. It was found that magmatic activity has been evolving at this location for at least the last 11-10 Myr and was distinctly discrete in character. Three stages of volcanism have been identified: (I) Early or Miocene, similar to 11-6.7 Ma; (II) Middle or Pliocene-Early Quaternary, 4-1 Ma; and (III) Late or Late Quaternary, 0.4-0.1 Ma. The most recent manifestations of magmatic activity in the region date back to about 100000 years ago. An analysis of the spatial distribution of volcanic centers of different ages in the Karacadag neovolcanic area shows that the magmatism of that region involved a lateral migration of activity from northwest to southeast along a major regional tectonic fault. The migration was caused by the movement of local tension zones where the lithosphere was thinner and deep-seated mantle magmas were ascending.
The Geochronology and Origin of Mantle Sources for Late Cenozoic Intraplate Volcanism in the Frontal Part of the Arabian Plate in the Karacadag Neovolcanic Area of Turkey. Part 2. The Results of Geochemical and Isotope (sr-Nd Studies
(Pleiades Publishing inc, 2012) Keskin, M.; Chugaev, A. V.; Lebedev, V. A.; Sharkov, E. V.; Oyan, V.; Kavak, O.
A geochemical and isotope-geochemical (Sr-Nd-Pb) study has been carried out for the Karacadag neovolcanic area, which is situated within the frontal part of the Arabian plate. The obtained data and the results of petrological modeling show that the petrogenesis of parental magmas in the Karacadag neovolcanic area involved two compositionally different mantle sources; one consisted of garnet-bearing peridotites of the asthenosphere mantle and the other was spinel-bearing peridotites of the enriched subcontinental lithosphere mantle. During early stages in the evolution of the magmatic system, deep-seated asthenospheric magmas were ascending to the surface while intensively interacting with the melts that had been generated at upper mantle depths. The interaction gradually diminished, so that the later effusive rocks mostly have compositions that are similar to those of the primitive asthenospheric magmas. It is shown that a significant (up to 17-18 wt % of the mantle melt) assimilation of crustal material could take place only during the initial phases of the magmatism. Periodic replenishment of the magma chambers by primitive magmas, which resulted in an observable high degree of homogeneity in the composition of young effusive rocks, was also of importance in the petrogenesis of lavas during the evolution of volcanic activity.
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.
Sources and Evolution of Miocene-Pleistocene Alkaline Magmatism in the Northeast Part of the Arabian Plate: Evidence From Sr-Nd Isotope Data and K-Ar Geochronometry
(Maik Nauka/interperiodica/springer, 2024) Chugaev, A. V.; Parfenov, A. V.; Lebedev, V. A.; Chernyshev, I. V.; Oyan, V.; Ozdemir, Y.; Pavlidis, S. B.
A geochronological and isotope-geochemical study of alkaline basalts from three areas of young magmatism within the northeastern part of the Arabian Plate (Southeastern Turkey), Batman, Kurtalan and Alemdag, was carried out. The obtained isotope data have indicated that the volcanism in the studied region developed over a 5-Ma period from the end of Miocene to the middle Pleistocene during four pulses separated by breaks in magmatic activity: 6.1-4.9 Ma (Batman area, hawaiites), similar to 3.0 Ma (Alemdag plateau, phase I, basalts), 2.0-1.9 Ma (Alemdag plateau, phase II, tephrites), and 1.5-1.3 Ma (Alemdag plateau, phase III, basalts; Kurtalan area, basalts). A comparison of spatial-temporal changes of magmatic activity evolution in the studied part of the Arabian Plate and within the largest basalt plateau of Arabian foreland, Karacadag Plateau, located to the west, was carried out. The results of Sr-Nd-Pb isotope-geochemical studies show that the development of young basalt volcanism in the Arabian Plate was characterized at different time by the contribution of various mantle sources in magma generation under this region. Initial pulses of magmatic activity are associated with melting of Arabian subcontinental lithospheric mantle (SCLM). The processes of fractional crystallization combined with crustal assimilation (AFC) have played an important role in the petrogenesis of lavas as well. Later, a deep mantle source (PREMA) with a depleted isotopic composition played a leading role in the formation of basaltic magmas of increased alkalinity. The melts generated by this source were mixed with the SCLM material in various proportions at different stages of magmatism with a limited participation of AFC processes in the petrogenesis of the rocks. It was concluded that young basalt volcanism of increased alkalinity in the northeast of the Arabian Plate is not related to the collision of the Eurasian and Arabian plates genetically, but presumably manifested here as a result of the migration of the initial rift geodynamic setting from the Red Sea basin to the north along Levantine and East Anatolian transform faults due to directed convection flows in the lower part of mantle under this part of the Earth.