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Bu çalışmada, Van gölü havzasındaki Van ve Arin göllerinin trona ve soda külü zenginliği araştırılmıştır. Sodyum ve karbon yönünden zengin bu göllerde doğal buharlaşma ile mevcut trona çökelmesi gözlemlenmiş ve göl sularından kimyasal yöntemlerle trona ve soda külü elde edilmiştir. Göllerden alınan 400 ml su numunesi üzerinde buharlaştırma, kalsinasyon, liç ve santrifüjleme yöntemleri uygulanmıştır. Bu deneyler sonucunda Van ve Arin gölü sularından sırasıyla 1 ve 3 gr trona ve soda külü elde edilmiştir. Bu veriler, 1 litre suda sırasıyla ortalama 2.5 ve 7.5 gr trona ve soda külü elde edilebileceğini göstermektedir. Nihai ürün olarak elde edilen soda külünün karakterizasyonunu belirlemek amacıyla X-ışınları kırınım (XRD), taramalı elektron mikroskobu (SEM-EDX) ve X-ışınları floresans (XRF) analizleri yapılmıştır. Nihai ürün üzerinde gerçekleştirilen XRD ve XRF analizleri, örneğin tamamına yakınının Na2CO3 (sodyum karbonat; soda külü) içerdiğini ve % 65 oranında Na2O içeriğine sahip olduğunu göstermiştir. SEM-EDX analizleri ham trona örneğine göre nihai ürünün Na ve C elementlerince zenginleştiğini ve nihai ürünün % 57-65 arasında Na2O içeriğine sahip olduğuna işaret etmiştir. Tüm bulgular, Van ve Arin göl sularının trona ve soda külü bakımından zengin olduklarını ve kimyasal yöntemlerle göl sularından soda külü elde edilebileceğini ortaya koymuştur.

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.

Maden Complex is a volcano-sedimantary unit, mainly composed of shallow and deep marine sedimentary rocks and associated volcanics. Deep marine units of Maden Complex, exposed between Çatak (Van) and Kozluk (Batman) regions have been studied with a combined sedimentological and paleontological approaches. The following species are recorded within the Melefan formation: Morozovella aragonensis, Acarinina collactea, Acarinina cf. esnehensis, Acarinina soldadoensis, Acarinina boudreauxi, Acarinina bullbrooki, Acarinina mckanni, Acarinina pentacamerata, Acarinina cf. pseudosubsphaerica, Acarinina topilensis, Acarinina esnehensis, Chiloguembelina sp., Globanomalina planoconica, Globanomalina australiformis, Globigerinatheka sp., Parasubbotina hagni, Pearsonites broedermanni, Pseudoglobigerinella bolivariana, Planoglobanomalina pseudoalgeriana, Pseudohastigerina wilcoxensis, Subbotina roesnaensis, Subbotina yeguaensis. Based on the defined planktonic foraminiferal species, the unit corresponds to the E7 zone and the depositional age of the formation is proposed as Early Eocene (Ypresian) to Middle Eocene (Lutetian). The deep marine sedimentary sequence mainly consists of pinkish to red colored micritic limestones including shale intercalations. The formation is represented by the pelloidal wackestone-packstone facies and comprises abundant planktonic foraminiferal assemblages.

Maden Complex exposed in Eastern Turkey, is a succession of volcano-sedimentary rocks and tectonically overlain by Bitlis Metamorphics and Cretaceous ophiolitic rocks. The succession includes shallow-water deposits and deep marine pelagic sediments intercalated with pillow lavas ranging from a few centimeters to ten meters in diameter. The planktonic foraminiferal assemblages from micritic limestones and zircon U-Pb ages from selected sedimentary rocks indicate the age of Late Ypresian - Early Lutetian. Plagioclase and clinopyroxenes are the main mineral phases, olivine rarely found as altered phenocrysts. Clinopyroxenes are augite and diopside, and their compositions are ranging between Wo44-51, En27-43, Fe10-21. The anorthite contents of plagioclases are between 32- 67 % in unaltered grains. The crystallization temperatures and pressures obtained from clinopyroxene chemistry are ranging from 1126 to 1250oC and 3 to 8 Kbar, respectively. The majority of the volcanic/subvolcanic rocks are subalkaline-tholeiitic basalts however; a few andesitic and rhyolitic derivatives are also present. The whole – rock and Sr-Nd-Pb isotope compositions reveal that the basaltic rocks are originated from E-MORB like asthenospheric mantle source without a subduction component.

The Eastern Anatolian region provides a good example for collision-related volcanic activity. This activity started during the Middle Miocene and continued through the Pliocene and Quaternary. The new K - Ar ages reveal that the post-collisional Pliocene Timar basalts located in the East Anatolian Accretionary Complex (EAAC) erupted between 4.72 (Zanclean) and 3.29-2.93 Ma (Piacenzian). The Pliocene Timar basalts consist of plagioclase, clinopyroxene (augite), and olivine minerals and have glomeroporphyritic, intergranular, and ophitic textures. They display enrichment in light rare earth elements (LREEs) with (La/Yb)(N) values that range between 3.19 and 6.66 to 21.63-5.61. Sr-87/Sr-86(i) and Nd-143/Nd-144(i) isotopic ratios of the Timar basalts are 0.70599-0.70436 and 0.51277-0.51259, respectively. The epsilon Nd(t) values of these rocks range between 1.0116 and 1.0121. Sr-87/Sr-86(i) and Nd(t) contents indicate crustal contamination during the emplacement of the Timar basalts. According to the Energy Constrained-Assimilation Fractional Crystallization (EC-AFC) model, this contamination rate is between similar to 1.4 and 4.4%. The melting model shows that the least evolved samples of the Timar basalts were formed by similar to 0.1-2% partial melting of the lherzolitic source. Primitive melts that constituent Timar basalts were occurred with partial melting of a magma source that has predominantly spinel bearing mineralogy. All data indicate that the origin of the parental melts of the Timar basalts is metasomatized lithospheric mantle source and then these melts reached the surface from the fissures that is related to extensional tectonics in Pliocene.

Hanonu massive sulfide (HMS) mineralization is the first sediment-hosted massive sulfide deposit discovered in Anatolia (Turkey). Containing more than 1% Cu and with more than 25 million tonnes reserve, the HMS mineralization is located in the Cangaldag Metamorphic Complex (CMC) in the central Pontides within meta-volcaniclastic rocks with mafic sill and/or lava interlayers. Rocks related to mineralization were exposed to metamorphism under the greenschist facies conditions. Tectonism and metamorphic processes affected all units including ore. The HMS mineralization consists dominantly of Cu (0.2–6.9%) accompanied by Zn (239 ppm–1%) and comprises massive, banded and disseminated sulfide bodies. The main ore minerals include pyrite, chalcopyrite, with minor sphalerite and magnetite. The regular stratigraphy displaying uninterrupted layers of volcanoclastics contains mafic lava or sills within the sequence with the mineralization initially emplaced within immature clastics and then subjected to metamorphism as a package, which indicates that the ore and wall rocks formed in the same paleotectonic environment. Data obtained from melt models of mafic lava or sills related to the HMS mineralization indicate these rocks formed in back-arc basins from a mixture of 70% depleted MORB mantle and 30% asthenospheric melt with melting degrees possibly of 8–15%. According to isotope data, lead from the HMS mineralization may be sourced from an arc-related environment, with magmatic activity in the lower crust and upper mantle. Geologic and geochemical data indicate that the HMS mineralization may have formed in a back-arc rift tectonomagmatic environment.

Türkiye’nin kuzeydoğusunda yer alan Pliyosen yaşlı Tutak volkanitleri, Doğu Anadolu Bölgesi’nde çarpışmayla ilişkili en önemli bazaltik platolardan biridir. Volkanik ürünler bazaltik bileşime sahiptirler ve alkali-subalkali ayrım çizgisi üzerine iz düşerler. Bazaltik kayaçların tamamı olivin, piroksen, plajiyoklaz ve opak mineral fenokristalleri ve mikrolitlerinden oluşur ve intersertal, subofitik ve akma dokuları sergilerler. Fraksiyonel kristallenme ve EC-AFC (enerjiye bağımlı fraksiyonel kristallenme, ile birleşik asimilasyon) modelleri Tutak volkanitlerinin evriminde fraksiyonel kristallenme ve kıtasal kirlenmenin önemli rol oynadıklarına işaret eder. En az evrimleşmiş (yüksek MgO içerikli lavlar) bazaltik örneklerinin düşük 143Nd/144Nd ve yüksek 87Sr/86Sr izotopik oranları ile büyük iyon yarıçaplı litofil (BİYÇL) ve hafif nadir toprak elementlerinin (HNTE), yüksek alan şiddetli elementlerine (YAŞE) göre belirgin zenginleşmesi, manto kaynak alanında yitim bileşeninin varlığına ve baskın olarak sediment ergimeleri ile zenginleştiğine işaret eder. Nadir torak element sistematiğinin kullanılması ile üretilen kısmi ergime modelleri, bazaltik ergiyiklerin kısmi ergime derecesi %0,7 ile %2 arasında değişen ve amfibol ile granat içeren metasomatize olmuş manto kaynağının ergimesi ile üretilebileceğini göstermiştir.

The Pliocene Etrusk 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. Etrusk 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 Etrusk volcano lasted ~ 600 kyr between 4.3–3.7 Ma during Zanclean times. The estimated depth of the Etrusk 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 Etrusk 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 Etrusk 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.

WOS: 000463308800009, The Quaternary (0.66-0.63 Ma) nepheline basanites (ne - basanite) are the firstly observed volcanic products of Arabia-Eurasia collision on Bitlis Pottirge Massif. They composed of clinopyroxene, olivine, Ti-magnetite, Cr spinel, and nepheline. The forsterite compositions of olivines range between 73 and 83%, calcic clinopyroxenes show modest variations in Wo(48-57)-En(37-45)-FS5-7 and nephelines occur as minor minerals within the networks of other groundmass minerals. They are characterized by low SiO2 (40.16-41.96 wt%), high MgO contents (8.54-9.73 wt%) and similar Sr-Nd isotopic compositions with Arabian Plate volcanics. Mineral and whole rock thermobarometry yield crystallization pressure and a temperature range between 8 and 20 kbar and 1301 degrees C - 1035 degrees C respectively. Lavas have high Mg -number (>0.58), high Cr and Ni contents and strong LREE enrichment but depletion in Rb, K, and Pb. Trace elements together with Sr isotopic compositions inferred negligible assimilation of the local upper crustal material. The calculated average pressure and temperature of mantle melting for ne-basanites is 2,85 kbar and 1353 degrees C respectively. FC3MS (wt% FeO/CaO-3*MgO/SiO2) parameter and melting models using REE data reveal catak basanites are products of amphibole and phlogopite bearing metasomatised lithospheric mantle in garnet stability field. They seem to originated from depths of similar to 85 km which corresponds to the base of the Arabian lithosphere in the region. (C) 2019 Elsevier B.V. All rights reserved., Van-Yuzuncu Yil University Scientific Research Project Foundation [2013-FBE-YL024]; TUBITAK the Scientific and Technological Research Council of Turkey [113Y406], This work has been funded by both Van-Yuzuncu Yil University Scientific Research Project Foundation (2013-FBE-YL024) and TUBITAK the Scientific and Technological Research Council of Turkey (Project No. 113Y406). Authors gratefully thank to Dan Mckenzie for his help in carrying out INVMEL. We also thank to Orhan Karsh, Zong-Feng Yang and Chief-Editor Nelson Eby for their constructive comments which helped in improving our paper.

Located in the north of Anatolia, the Pontide Orogenic Belt hosts Turkey's most important volcanogenic massive sulfide (VMS) deposits. Studies completed in the last ten years have discovered new massive sulfide deposits in the Central Pontide zone. The Zeybek VMS deposit is one of these newly-discovered deposits found in the Central Pontides. This deposit is associated with the Çangaldağ Metamorphic Complex occurring as east-west-striking tectonic slices. The Çangaldağ Metamorphic Complex is an allochthonous mass of metavolcanic, metavolcaniclastic and metaclastic rocks in the form of imbricated tectonic slices. Zeybek massive sulfide deposit is located within metaclastic rocks intercalated with mafic sills or lava flows in this complex. The major ore mineral paragenesis in the Zeybek VMS deposit comprises pyrite, chalcopyrite and sphalerite, with lower amounts of bornite, covelline, chalcocite and magnetite. With thirty thousand meters of drilling in the mineralized area, 20 million ton resources with 0.32 wt% Cu were determined. According to the wall-rock mineralization relationships, mineralization style and ore geochemistry of the Zeybek VMS mineralization, it is similar to a mafic-siliciclastic type volcanogenic massive sulfide formation. Re-Os geochronologic studies of chalcopyrites from the Cu-rich massive ore samples obtained a 178 ± 2.2 Ma (MSWD: 4.1) 187Re/188Os against 187Os/188Os isochron. Geochemical and isotopical age data associated with the Zeybek VMS deposit indicate that the mineralization occurred in an arc-back arc tectonic environment, which developed in Middle Jurassic age intra-ocean as a result of the closure of north-ward subduction that resulted the closure of the Tethys ocean. © 2019 Elsevier B.V. National Basic Research Program of China (973 Program): 2018YFC0604006 National Natural Science Foundation of China: 41572077 We would like to thank to all MTA staff who assigned in this project. We would like to thank to editor Franco Pirajno and reviewers for their constructive criticism contributions. This study has been prepared based on the project of ‘Polimetal ore exploration of Kastamonu province surounding in General Directorate of Mineral Resource and Exploration (MTA); with the project number (2013/2019)-32-13-05. Within the scope of this project we thank geological engineers Kenan ÇOŞKUN, Aysun SÖZCÜ, Aydın Olcay ÇOLAKOĞLU, Serdar KESKİN, Furkan ERDEM, Özkan YILDIRIM, Buğra GÖKÇEOĞLU, Ercüment AYSERT and Mehmet KÖKSAL, Onur TİRYAKİ for field and laboratory studies. We are grateful to geological engineers Füsun NİĞDELİ, Mustafa TOKOĞLU, and Yusuf Mehmet ERDEM and mining engineer İsmail ÖKSÜZ for completing solid model and feasibility studies related to mineralization. The National Key Research and Development Program of China ( 2018YFC0604006 ) and National Natural Science Foundation of China ( 41572077 ) have supported this study Re/Os age analizes. Appendix A

Mafic alkaline lavas in Turunclu-Delihalil region (Osmaniye) in southern Turkey erupted from extensional fractures and volcanic cones such as Delihalil and Dctepeler along strike-slip fault systems in the Iskenderun Basin, which is bordered by Misis-Andinn complex (MAC) that is an accretionary prism. New Ar-Ar dating results indicate that volcanic activity occurred between similar to 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 spinet 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 degrees C at pressures of 2.8-3.7 GPa. (C) 2018 Elsevier B.V. All rights reserved.

The Early Miocene Taskapi-Mecitli granitoid that is located in the northern section of the Eastern Anatolia Collision Zone has typical I-type, metaluminous and calk-alkaline characteristics. It also contains mafic microgranular / magmatic enclaves (MMEs). New Ar-Ar dating results show that the age of the Taskapi-Mecitli granitoid is ∼23 Ma and it crystallised in the Early Miocene, in contrast to its previously known Cretaceous age. Identical crystallisation ages (∼23 Ma), similar mineral assemblages and geochemical compositions, and indistinguishable isotopic compositions of MMEs and host rocks imply that the MMEs are most consistent with a cumulate origin formed at earlier stages of the same magmatic system that produced the Taskapi-Mecitli granitoid. MELTS modelling suggests that magma of the Taskapi-Mecitli granitoid was the result of fractionation under a crustal pressure of 4 kbar, with a H2O content of 1.5%. EC-AFC model calculation reveals that the Taskapi-Mecitli granitoid includes from 0.5% to 2% crustal assimilation rates. These rates indicate that crustal contamination can be negligible when compared to fractional crystallisation in the evolution of the magma beneath the Taskapi-Mecitli granitoid. The partial melting model calculations and MORB-normalised trace element concentrations of the least evolved samples of the Taskapi-Mecitli granitoid are consistent with those of mafic melts obtained from partial melting of interacting mantle- lower crust with a melting degree of 18%. The age (23 Ma) of the post- or syn-collisional Taskapi-Mecitli granitoid suggests that the collision between Arabian and Eurasian plates could be before/around ∼23 Ma (Late Oligocene to Early Miocene).

Ignimbrites are used extensively in masonry and decorative cladding not only in historical structures, but also in residential houses recently as well as monuments around Ahlat (Bitlis-Turkey) region because of their light weight, softness and insulating properties. The most famous architectural monument is the Ahlat Seljuk Tombs, in which ignimbrites were used for the structure. These are thousand year old gravestones that have been subjected to significant degradation over time caused by many physical and chemical effects. The aim of this study is revealing the mineralogical, petrographical, petrophysical and mechanical properties of fresh ignimbrites as well as determining the effect of lichens and capillarity on the deterioration of Seljuk gravestones in accordance with laboratory studies and field observations. A total of four different ignimbrite levels have been evaluated, which are widespread in the region and named as N1 (reddish brown), N2 (dark brown), N3 (yellowish gray) and N4 (black), respectively. Among these ignimbrites, the samples of N1 and N2 were employed in the construction of Seljuk gravestones. The lithic material content and welding degree are the main controlling factors of the engineering properties of ignimbrites. Laboratory test results indicate that high porosity of ignimbrites and transport of water mediated by capillarity accelerate the deterioration of ignimbrites. Furthermore, lichens play a preventive role in the deterioration mechanism of ignimbrites rather than disintegrating the tombstones. (C) 2014 Elsevier B.V. All rights reserved.

Van Golu’nun dogusundaki carpisma ile iliskili Otlakbasi volkanizmasi farkli acilma catlaklarindan puskurerek meydana gelmistir. Bu calismada, Otlakbasi bazaltik volkanizmasinin yeni yas verisi ve ana oksit, iz ve nadir toprak element jeokimyasal karakteristikleri incelenmistir. Ar-Ar yas verisi bu bazaltik volkanizmanin bilinen Kuvaterner yasinin aksine Erken Pliyosende puskurdugune isaret eder. Volkanik urunleri alkali-subalkali ayrim cizgisine yakin ve bazaltik bilesimdedirler. Fraksiyonel kristallenme ile birlesik kitasal kirlenme (AFC) modellerinin sonuclari, magma odasi evrim sureclerinde fraksiyonel kristallenmenin kitasal kirlenmeye gore ihmal edilebilir olduguna ve kitasal kirlenmenin fraksiyonel krsitallemeye oraninin ( r degeri) 0.1 ile 0.35 arasinda degistigine isaret eder. Buyuk iyon yaricapli litofil elementlerin ve (BIYL) hafif nadir toprak elementlerin (HNTE) yuksek alan siddetli elementlere (YASE) gore zenginlesmesi ve hareketli iz elementlerin (Ba, Th) davranisi, Otlakbasi bazaltik volkanizmasinin manto kaynak bolgesinin dalmis sedimentlerden tureyen ergiyikler ile zenginlestigini ortaya koymustur. Fraksiyonlanma dogrulamasi yapilan orneklerin Rb ve K elementlerindeki tuketilme, manto kaynak alaninda flogopit ve/veya amfibolun var olabilecegine isaret eder. Kismi ergime modelleme calismalarinin sonuclari, bu bazaltik volkanizmanin baskin olarak spinel peridotit kaynaginin ergimesi ile uretilebilecegini gostermistir. Metasomatize olmus spinelce zengin litosferik mantonun ergimesi, Otlakbasi bazaltik volkanizmasinin puskurmesinden sorumlu olabilir.

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 1.0 and 0.4 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 Sr-87/Sr-86 and Pb isotopic ratios and lower Nd-144/Nd-143 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 similar to 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 0.01% residual rutile, added to mantle melt, could have been the source composition of the basaltic melts that produced the Quaternary mafic volcanism.

International audience; The Quaternary Süphan debris avalanche deposit is located in Eastern Anatolia, Turkey. The avalanche formed by the sector collapse of a major stratovolcano towards the north, possibly during a single catastrophic event. The deposit has an estimated volume of 4 km3 and ran out over 25 km to cover an area of approximately 200 km2. Products of the collapse are overlain by younger eruptive units from the Süphan volcano. We have tested the numerical code VolcFlow to first reproduce the emplacement of the Quaternary Süphan debris avalanche and then to develop a hazard assessment for potential future sector collapses and subsequent emplacement of debris avalanches and associated tsunami. The numerical model captures the main features of the propagation process, including travel distance, lateral spread, and run up. The best fit obtained for the existing flow has a constant retarding stress of 50 kPa and a collapse scar volume of 4 km3. Analysis of potential future collapse scenarios reveals that northern sector debris avalanches (up to 6 km3) could affect several towns. In the case of a sector collapse towards the south, a tsunami will reach the city of Van and several of the biggest towns on the southern shoreline of Lake Van. Cities most affected by the larger amplitude waves would be Van, Edremit, Gevaş, Tatvan, and, to a lesser extent, Erciş, with wave amplitudes (first waves after the onset of the collapse) between 8 and 10 m.

An isotope-geochronological study has been performed to examine the products of Late Cenozoic collision volcanism on the northern coast of Lake Van, Turkey. We obtained 45 new K—Ar dates, based on which the principal time characteristics of volcanic activity in the region have been determined. Volcanic activity in the northern coast of Lake Van has lasted ∼15 myr; it has had an expressed discrete nature, when periods of intense volcanic activity alternated with long-lasting pose periods. Four stages of Neogene—Quaternary volcanism have been identified: Middle Miocene (15.0—13.5 Ma), Late Miocene (10—9 Ma), Pliocene (5.8—3.7 Ma), and Quaternary (1.0—0.4 Ma). The average duration of the stages was 1—2 myr; the stages were separated from each other with periods of inactivity of approximately equal lengths (∼3 myr). For each of the Pliocene and Quaternary stages, three additional phases of volcanism have been identified, which were separated from each other with short time intervals (a few hundred thousand years). The last burst of volcanic activity in the study area occurred ∼400 ka; similar to Quaternary volcanism in general, it was not characterized by a high intensity. An important result of the studies performed was to confirm the existence of a separate Middle Miocene stage of collision volcanism for the Caucasian—Anatolian Segment of the Alpine Fold Belt. New geochronological data generated presented in this paper indicate that Neogene—Quaternary volcanism in this portion of the belt started much earlier (∼15 Ma) than assumed by the majority of the previous researchers.

In the present study, the potential effects of physical, chemical and electro-kinetic properties of pumice on the strength development of pumice blended cements (PBC) were examined and documented. A significant relationship between zeta potential of pumice samples, setting time and water demand of PBC was found. A relationship between the chemical content of pumice samples and compressive strength of PBC was also observed. However, zeta potential of the pumice samples was found to be less effective in strength development. Despite the lower clinker content, the setting time of the PBC samples was shorter than control specimen. 30 % pumice replacement by clinker resulted in 5–28 % reduction in 28-day strength depending on the characteristics of the pumice samples and grinding time.

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.

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.

An isotope-geochronological study has been performed to examine the products of Late Cenozoic collision volcanism on the northern coast of Van Lake, Turkey. We obtained 45 new K-Ar dates, based on which the principal time characteristics of volcanic activity in the region have been determined. The total duration of magmatic activity in the area of the northern coast of Van Lake has lasted similar to 15 myr; it has had an expressed discrete nature, when periods of intense volcanic activity alternated with lasting breaks in eruptions. Four stages of Neogene-Quaternary volcanism have been identified: Middle Miocene (15.0-13.5 myr), Late Miocene (10-9 myr), Pliocene (5.8-3.7 myr), and Quaternary (1.0-0.4 Ma). The average duration of the stages has been 1-2 myr; the stages were separated from each other with periods of inactivity of approximately equal lengths (similar to 3 myr). For each of the Pliocene and Quaternary stages, three additional phases of volcanism have been identified, which were separated from each other with short time intervals (a few hundred thousand years). The last burst of volcanic activity in the area in question took place similar to 400 ka; similar to Quaternary volcanism in general, it was not characterized by a high intensity. An important result of the studies performed was to confirm the existence of a separate Middle Miocene stage of collision volcanism for the Caucasian-Anatolian Segment of the Alpine Fold Belt. The data generated allow concluding that Neogene-Quaternary volcanism in this portion of the belt started much earlier (similar to 15 Ma) than assumed by the majority of the previous researchers.