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The temporal distribution of enriched source components and magmatism in continental collision zones provides critical information about mantle dynamic processes in collision-related environments. This paper presents petrology, mineralogy, K-Ar ages and whole-rock major and trace elements, as well as Sr-Nd-Pb-Hf isotopic compositions of Melikler volcanism in Kars Plateau (KP) in the East Anatolia Collision Zone, NE Turkey, with the aim to understand the role of the subducting slab, the origin of magmatism and the geodynamic evolution in the collision-related environments. Our K-Ar dating results show the Melikler volcanism erupted between 5.29 and 1.7 Ma and allows us to divide it into an early (5.29–2.53 Ma) and a late (2.24–1.7 Ma) stage. Major-trace element abundances, isotopic compositions, EC(R) AFC (energy-constrained recharge, assimilation, and fractional crystallisation) and MELTS model calculations of both stages indicate that the least evolved samples were not affected by significant crustal contamination and fractional crystallisation. More evolved samples of the late stage underwent AFC processes with up to 6–9% crustal assimilation; however, those of the early stage were differentiated from a parental magma composition via AFC (up to 2–7.5% crustal assimilation) and experienced magma replenishment at pressure of 0.5 kbar; thus, both early and late stages have experienced open system conditions. The least evolved samples of both stages across the KP have arc-enriched geochemical and isotopic signatures, characterised by prevalent negative Nb–Ta anomalies and moderately radiogenic Sr, unradiogenic Nd-Hf and highly radiogenic Pb isotopic compositions. These primary melts could be derived from a depleted MORB mantle source metasomatised by sediment melt from the subducting Neotethys oceanic slab. Combined trace elemental and isotopic modelling results suggest that the least evolved samples of the early stage were formed by 2–4% melting of an amphibole-bearing garnet lherzolitic mantle source, which was metasomatised by 0.3–0.5% contribution of subducted slab component with a ratio of sediment melt/AOC (altered oceanic crust) melt about 90:10. A depleted lherzolitic mantle source containing apatite and garnet through inputs of 0.6–0.8% melts derived from the subducted oceanic slab, with 5–10% partial melting degree, could produce the least evolved samples of the late stage. Thermobarometric calculations reveal that the least evolved samples of the late stage are derived from the lithosphere-asthenosphere boundary at a depth of 77–82 km; in contrast, those of the early stage are produced from the lithosphere at a depth of 66–69 km. Literature data and the findings obtained from this study indicate that the onset of the Arabian-Eurasian collision may have occurred in the Oligocene and lithospheric dripping caused by the hard collision that occurred around the Late Miocene-Early Pliocene may produce the Melikler volcanic rocks. [ABSTRACT FROM AUTHOR]

Geochemical and isotopic markers of the most primitive basaltic melts allow us to understand the temporal evolution of the lithospheric mantle and geodynamic processes. This paper presents the geochemical, Sr-Nd-Pb-Hf isotopic data, K Ar dating and the petrological evolution of the petrogenesis of the late Miocene-early Pliocene basaltic volcanism observed in the Baltacık-Günkoru region in the northeastern of Lake Van in Eastern Anatolia Collision Zone (EACZ). These data allow us to understand the origin of collision-related magmatism and the geodynamic processes in the late Miocene-early Pliocene in the EACZ. Geochronological age data (K Ar) indicate that basaltic volcanism erupted between ∼7.63 and 5.24 Ma. Major-incompatible trace element contents, Sr Nd isotopic compositions of the studied samples and EC-AFC (energy-constrained recharge, assimilation, and fractional crystallization), and MELTS model calculations point out that basaltic volcanism has undergone fractional crystallization but unaffected crustal contamination. Petrological models created using 87Sr/86Sr, ℇNd and ℇHf isotopic data, together with calculated primary melt compositions of basaltic lavas, indicate that the DMM-type (Depleted Morb Mantle) mantle source is metasomatized by melts rather than fluids derived from subducted oceanic lithosphere. Combined trace element and isotopic modelling results indicate that the calculated primary melts were formed by 2.5–5% melting of a metasomatised spinel-garnet lherzolitic mantle source, including amphibole and 1% residual rutile. This mantle source has been metasomatised by a 1–3% contribution of subducted slab component, with a sediment melt/AOC (altered oceanic crust) melt ratio of about 90:10. Thermobarometric calculations based on calculated primary melts compositions indicate that the lithosphere-asthenosphere boundary (LAB) is a depth of 67 ± 4 km for 7.53–5.24 Ma. Literature data and the findings obtained from this study indicate that the late Miocene to early Pliocene basaltic volcanism in the south of the EACZ) is progressed by the delamination of the mantle lithosphere. This delamination occurred in a fragmented/patched or dripping manner rather than whole-scale delamination in the 3–4 million years between ∼9 Ma and 5–6 Ma. [Display omitted] • Studied basalts erupted in the Late Miocene to Early Pliocene. • LAB under EACZ decreased from Late Miocene to Early Pliocene via delamination. • Delamination emerged fragmented/patched or dripping rather than a whole scale. [ABSTRACT FROM AUTHOR]

Mafic alkaline lavas in Turunçlu-Delihalil region (Osmaniye) in southern Turkey erupted from extensional fractures and volcanic cones such as Delihalil and Üçtepeler along strike-slip fault systems in the İskenderun Basin, which is bordered by Misis-Andırın complex (MAC) that is an accretionary prism. New Ar Ar dating results indicate that volcanic activity occurred between ~2.1 Ma (alkali basaltic melts) and 120 ka (basanitic melts). The volcanic products are alkaline in character. Major and trace element abundances and EC-AFC models using Sr and Nd isotopic ratios are used to propose that the basanitic samples were subjected to fractional crystallisation but were not affected by significant crustal contamination in contrast to the alkali basaltic samples which contain up to 2–5% crustal assimilation. Partial melting models using fractionation-corrected data indicate that the petrogenesis of the alkali basalts can be explained by mixing of melts from phlogopite-bearing garnet peridotite with melts from phlogopite bearing spinel peridotite, in contrast to basanites which could have been derived only from the phlogopite bearing garnet peridotite mantle source. It is inferred that the phlogopite may have formed in lithosphere-asthenosphere boundary by metasomatic melts or fluids from a rising asthenospheric mantle. Melt generations with residual phlogopite indicate melting at temperatures of 1275–1390 °C at pressures of 2.8–3.7 GPa. [ABSTRACT FROM AUTHOR]

Collision-related Quaternary mafic volcanism to the north of Lake Van (Eastern Anatolia, Turkey) occurred by eruptions from both volcanic centres and extensional fissures trending approximately north-south. We report new major, trace and rare earth element abundances, Sr-Nd-Pb isotope ratios and K-Ar ages for basaltic and more evolved hawaiitic and mugearitic lava flows. The new K-Ar ages indicate that magmatic activity occurred between 10 and 04 Ma. The volcanic products consist of mildly alkaline lavas, ranging in composition from basalt to hawaiite and mugearite. Energy-constrained assimilation and fractional crystallization (EC-AFC) model calculations suggest that the least evolved basaltic samples were unaffected by the combined effects of fractional crystallization and crustal contamination processes, in contrast to the more evolved hawaiitic and mugearitic lavas, which have experienced up to 2-3% crustal assimilation. Calculations based on crustal temperatures and Curie point depths indicate that the magma chamber, from which the basic to evolved lavas were derived, might be located at a depth of around 6-8 km, within the upper crust. Enrichment of large ion lithophile elements and light rare earth elements relative to high strength field elements, and higher 87Sr/86Sr and Pb isotopic ratios and lower 144Nd/143Nd of the least evolved basaltic samples indicate that the mantle source region of the Quaternary mafic magmas might have been enriched by melts that were derived from subducted sediments with a partial melting degree of around 10% rather than from Altered Oceanic Crust melts and fluids. Our model melting calculations show that the basaltic melts might have been produced by melting of a mantle source containing both amphibole and garnet with a partial melting degree of 3%. Results of our petrological models indicate that a metasomatized mantle source, which was infiltrated by a mixture of 93% mantle melt and 7% sediment melt plus 001% residual rutile, added to mantle melt, could have been the source composition of the basaltic melts that produced the Quaternary mafic volcanism. [ABSTRACT FROM AUTHOR]

The Pliocene Etrüsk stratovolcano, located in the northeast of Lake Van (Eastern Anatolia; Turkey), is one of the important volcanic centres in the Eastern Anatolian collision zone. Mt. Etrüsk overlies a widespread volcanic plateau, consisting of basaltic and hawaiitic lavas formed by fissure eruptions between 4.9–4.5 Ma. These basic lavas contain a phenocryst phase consisting of olivine, plagioclase and clinopyroxene. Trace element ratio diagrams imply that these basic magmas were generated from a mantle that contained a clear subduction component that is related to the subducted sediments rather than fluids or altered oceanic crust. Results of the melting models on the basaltic plateau lavas indicate that there was a marked variation both in the mantle source mineralogy (i.e. the ratio of garnet peridotite to spinel peridotite in the source varies between 60/40% and 40/60%) and the degree of melting (i.e. F between 0.8–4%). This can be explained by a model in which magmas were generated by partial melting of both metasomatised lithospheric and deeper asthenospheric mantle sources in an extensional setting in response to the partial delamination of the lithospheric mantle of Eastern Anatolia and then mixed with each other during Pliocene times. Central eruptions that formed the Etrüsk volcano lasted ~ 600 kyr between 4.3–3.7 Ma during Zanclean times. The estimated depth of the Etrüsk magma chamber is ~ 9–12 km. The volcano erupted lavas with a rather narrow compositional range from latite to rhyolite, which are either transitional or mildly alkaline in character. The Etrüsk lavas contain plagioclase, clino- and orthopyroxene, biotite, K-feldspar and rarely, minor amounts of olivine and amphibole in the phenocryst phase. A composite chemo-stratigraphic section of the volcano and petrological models indicate that the evolved lavas of the Etrüsk volcano differentiated from a parental magma composition, which is similar to that of the most primitive plateau basalt lavas underlying the volcano, via the AFC process, and experienced at least two major magma replenishment episodes at 4.1 Ma and 3.8 Ma during the magma chamber evolution. [ABSTRACT FROM AUTHOR]

[Display omitted] • Say Yayla VMS deposit is associated with Middle Jurassic arc volcanism. • Say Yayla VMS occurred in an arc tectonic environment. • Mafic and felsic metavolcanics are the host-rocks of the Say Yayla VMS. The central part of the Pontide Orogenic Belt, located in northern Anatolia, is a segment of the Alpine-Himalayan orogeny. Çangaldağ Metamorphic Complex (CMC) occurs within this segment which consists of ensimatic island arc volcanics and deep sea sediments which occasionally cut cross by mafic sills/dykes. They were exposed to metamorphism under the greenschist facies conditions and remain in tectonic contact with each other. The Say yayla mineralization is one of the recently discovered volcanogenic massive sulfide (VMS) deposits in the CMC with a remarkable Au content. The mafic and felsic metavolcanic rocks are the host-rocks of the Say Yayla mineralization and the ages determined by U-Pb zircon grains of these felsic volcanic rocks range from 170 Ma to 165 Ma indicating Middle Jurassic time. At the 0.1% cut-off grade, 7.5 million tons of resource has been calculated with 0.75 ppm Au, 0.65 wt% Cu, and 0.35 wt% Zn grades. The Say Yayla mineralization consists of massive and semi-massive sulfide minerals and a mineral assemblage represented by predominantly pyrite and chalcopyrite and trace amounts of sphalerite, tennantite and galena. Average base and precious metal grades of the zones occur with >1 wt% Cu are 2 wt% for Cu, 0.7 wt% for Zn, 0.04 wt% for Pb and 1.5 g/t for Au. The sulfur isotope values (δ34S VCDT) range from 4.9‰ to 6.7‰ for pyrite grains and 4.2‰ was obtained from the one sphalerite sample. δ18O values for the quartz from quartz-rich ore samples were 10.6 ‰ and 11.7‰ δ18O (VSMOW) qtz. δ18O (VSMOW) fluid values for the ore-forming fluids vary between 0‰ and 2.4‰. Lead isotope compositions of the pyrite minerals were 18.148–18.150 (206Pb/204Pb), 15.548–15.550 (207Pb/204Pb) and 38.078–38.083 (208Pb/204Pb) The geological, geochemical, and isotopic data of the ore and host-rocks reveal that the mineralization is a bimodal-mafic type (Noranda type), which is classified into Cu-Zn group of volcanogenic massive sulfides. Geochemical and geochronological data from the wall rocks further show that mineralization was developed within an ensimatic island arc environment during the Middle Jurassic. [ABSTRACT FROM AUTHOR]