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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]

The Early Miocene Taşkapı-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 Taşkapı-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 Taşkapı-Mecitli granitoid. MELTS modelling suggests that magma of the Taşkapı-Mecitli granitoid was the result of fractionation under a crustal pressure of 4 kbar, with a H 2 O content of 1.5%. EC-AFC model calculation reveals that the Taşkapı-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 Taşkapı-Mecitli granitoid. The partial melting model calculations and MORB-normalised trace element concentrations of the least evolved samples of the Taşkapı-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 Taşkapı-Mecitli granitoid suggests that the collision between Arabian and Eurasian plates could be before/around ∼23 Ma (Late Oligocene to Early Miocene). [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]

In Eastern Anatolia, the Karayazı–Göksu basaltic plateau is one of the basaltic eruption centers of post-collisional volcanism, located between the convergence zone of the Arabian and Anatolian plates. The geological and geochemical evolution of the plateau is documented using new 40Ar/39Ar age data, major-and trace element abundances, mineral geochemistry, and isotope compositions (Sr–Nd–Hf) for better understanding the petrogenesis and mantle source characteristics. Samples yield whole-rock 40Ar/39Ar ages of 12.53 ± 0.05 and 12.68 ± 0.05 Ma for transitional basalts (Middle Miocene), 5.88 ± 0.20 Ma for tholeiitic lavas (Late Miocene), and 2.28 ± 0.03 and 2.48 ± 0.12 Ma for alkali members (Early Quaternary). The results suggest that the fractional crystallization of olivine and clinopyroxene in transitional, tholeiitic and lower alkaline lavas, and clinopyroxene in upper alkaline lavas, played a crucial role in their magmatic evolution without significant crustal contamination. Clinopyroxene-liquid equilibria indicate that the crystallization of transitional basalts occurred at the Moho and lower crust (temperature range 1157–1215 °C), tholeiitic basalts at the lower crust (temperature range 1154–1195 °C), alkaline basalts at lower to mid-crustal depths (temperature range 1083–1195 °C). The subduction-related metasomatism is in the form of melts derived from subducted sediments and decrease from Middle Miocene transitional to alkaline Early Quaternary basalts, as indicated by the Sr–Nd–Hf isotopes and Ba/La and Th/Yb contents. The Early Quaternary alkaline basalts contain contributions from isotopically depleted but chemically enriched (enriched-MORB-like) asthenospheric mantle domain. Major elements–based parameters and olivine mineral chemistry yield that Karayazı–Göksu basalts could not be derived from a sole peridotite mantle source; the pyroxenite/eclogite-like mantle component would have contributed to the members of the plateau. Three-component mixing results using Sr Nd isotopes indicate that the altered oceanic crust contributes to 0.5%–1% of the melt (crust vs. sediment about 65:35) for tholeiitic and alkaline basalts and reach up to 4% for transitional basalts (crust vs. sediment about 55:45). Melt equilibration depths of the basalts indicate that the lithospheric thickness of the region has not been changed on a large scale since the Middle Miocene to the Early Quaternary. [Display omitted] • Middle-Miocene to Early-Quaternary basaltic rocks. • Decreasing subduction influence from Middle Miocene to Early Quaternary. • E-MORB like asthenospheric mantle component for younger members. • Localized removal of Eastern Anatolian lithospheric mantle. [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]

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. 87Sr/86Sr(i) and 143Nd/144Nd(i) isotopic ratios of the Timar basalts are 0.70599–0.70436 and 0.51277–0.51259, respectively. The εNd(t) values of these rocks range between 1.0116 and 1.0121. 87Sr/86Sr (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 ~1.4 and 4.4%. The melting model shows that the least evolved samples of the Timar basalts were formed by ~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. • The post-collisional Pliocene Timar basalts in the Turkish-Iranian high plateau. • The Geochemical and geochronological features of the Timar basalts. • The partial melting of a metasomatized spinel–rich lithospheric mantle source. • The EC-AFC modelling for the Pliocene Timar basalts. [ABSTRACT FROM AUTHOR]

Abstract The Quaternary (0.66–0.63 Ma) nepheline basanites (ne - basanite) are the firstly observed volcanic products of Arabia-Eurasia collision on Bitlis Pötürge 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 -Fs 5–7 and nephelines occur as minor minerals within the networks of other groundmass minerals. They are characterized by low SiO 2 (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 °C – 1035 °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 °C respectively. FC3MS (wt% FeO/CaO-3*MgO/SiO 2) parameter and melting models using REE data reveal Çatak basanites are products of amphibole and phlogopite bearing metasomatised lithospheric mantle in garnet stability field. They seem to originated from depths of ~ 85 km which corresponds to the base of the Arabian lithosphere in the region. Graphical abstract Unlabelled Image Highlights • The firstly observed collision related volcanics in Bitlis Suture Zone • The calculated average pressure and temperature of mantle melting is 2,85 kbar and 1353 °C. • They formed through the melts from Arabian Lithospheric mantle beneath the Bitlis Massif. [ABSTRACT FROM AUTHOR]

Graphical abstract Hıghlıghts • HMS is the first sediment-related VMS deposit discovered in the Anatolia. • Containing more than 1% Cu-25 million tons reserve, ÇMC. • HMS mineralization may have formed in a back-arc rift tectonomagmatic environment. Abstract Hanönü 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 Çangaldağ 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. [ABSTRACT FROM AUTHOR]

• Zeybek massive sulfide deposit is one of the recent discoveries, which is located in Turkey. • The Zeybek VMS mineralization is similar with mafic-siliciclastic type VMS deposits. • Cu-rich massive ore samples yielded, 178 ± 2.2 Ma (MSWD: 4.1) by Re-Os geochronological age. • The Zeybek VMS occurred in an arc-back arc tectonic environment. 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. [ABSTRACT FROM AUTHOR]

The Seljuk Tombs of the Seljuk Empire in the Ahlat region are included in UNESCO's World Heritage Tentative List due to the fact that the tombstones are known to be the largest graveyards of Muslims with their historical significance. Tombstones were erected using ignimbrite type pyroclastic rocks which are widespread in the region, and several inscriptions and patterns were carved on them thanks to their softness and easy processing. However, these tombstones have been subjected to weathering effects for almost a duration of 800 years. The most striking point after the inspection of tombstones is that many of them were broken from the middle section. In this study, experimental studies were carried out on fresh ignimbrite specimens and particularly the effect of capillary water absorption on deterioration was investigated to reveal the factors leading to deterioration of Ahlat Seljuk tombstones. Accordingly, high porosity and capillary water absorption characteristics of the ignimbrites are found to be the major reasons for the deterioration of tombstones. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]