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The geodynamic evolution of the South Armenian Block (SAB) within the Tethyan realm during the Palaeozoic to present-day is poorly constrained. Much of the SAB is covered by Cenozoic sediments so that the relationships between the SAB and the neighbouring terranes of Central Iran, the Pontides and Taurides are unclear. Here we present new geochronological, palaeomagnetic, and geochemical constraints to shed light on the Gondwanan and Cimmerian provenance of the SAB, timing of its rifting, and geodynamic evolution since the Permian. We report new 40Ar/39Ar and zircon U-Pb ages and compositional data on magmatic sills and dykes in the Late Devonian sedimentary cover, as well as metamorphic rocks that constitute part of the SAB basement. Zircon age distributions, ranging from ∼3.6 Ga to 100 Ma, firmly establish a Gondwanan origin for the SAB. Trondhjemite intrusions into the basement at ∼263 Ma are consistent with a SW-dipping active continental margin. Mafic intraplate intrusions at ∼246 Ma (OIB) and ∼234 Ma (P-MORB) in the sedimentary cover likely represent the incipient stages of breakup of the NE Gondwanan margin and opening of the Neotethys. Andesitic dykes at ∼117 Ma testify to the melting of subduction-modified lithosphere. In contrast to current interpretations, we show that the SAB should be considered separate from the Taurides, and that the Armenian ophiolite complexes formed chiefly in the Eurasian forearc. Based on the new constraints, we provide a geodynamic reconstruction of the SAB since the Permian, in which it started rifting from Gondwana alongside the Pontides, likely reached the Iranian margin in Early Jurassic times, and was subject to episodes of intraplate (∼189 Ma) and NE-dipping subduction-related (∼117 Ma) magmatism.

Widespread volcanism played significant role in geological history of Anatolian-Armenian-Iranian orogenic plateau formed as a result of continental collision of Arabian and Eurasia. Among diverse chemical compositions and eruption styles, reported for volcanoes of Armenian highlands, noteworthy are distal tephra fallout deposits and voluminous ignimbrite shields resulted from violent explosive volcanic eruptions with VEI estimations ranging form 4 to 6. Obviously, such eruptions had significant impact on climate, human occupation and migrations in the entire region and provide insights to volcanic hazards in the region. One difficulty in the identifying and studying explosive eruptions during Pleistocene, is that many tephra fallout deposits are not preserved in the geologic records, since unconsolidated deposits erode rapidly, particularly in mountain topography. In Armenia, there is a sparse geologic record of tephra fallouts, except where these deposits are preserved beneath pyroclastic flows, which presumably occurred very soon after tephra deposition. Such tephra deposits, are known in Armenia in underlying ignimbrite units related to activity of Aragats stratovolcano (Gevorgyan et al., 2018), beneath Ani ignimbrite in western part of Armenia and activity of Irind and Pemzashen volcanoes. Alternatively, tephra deposits can be preserved if layers are rapidly covered by loess deposits or colluvium deposits or landslides shortly after the eruption and tephra deposition occurs. Such conditions are known for distal tephra fall deposits from Ararat volcano in Ararat depression and in NE Armenia near Ijevan. A big number of finds of Paleolithic stone tools, and resent achievements in studying Paleolithic archeology in south Caucasus region provide evidences of early human occupation in the territory of south Caucasus. This contribution aims to fill gaps in our knowledge of distal tephra layers identified in Armenia, namely in north-east, south and central parts of Armenia. New data based on detailed geochemical investigations and 40Ar/39Ar age determinations of distal tephra layers originated from violent explosive eruptions, reported in this study, can contribute to establish chronostratigraphic horizons as marker layers for paleoclimate and archaeological records during Middle-Upper Pleistocene in the entire region. Tephra layers preserved in Pleistocene sedimentary sequences in Armenia provide important information about these violent explosive eruptions that are significant for the geological evolution and the human geography of the entire region.

In this contribution we discuss the geological structure, temporal and spatial relationships of Gegham upland between polygenetic and monogenetic volcanic activity as well as transitions from one to another as well as geochemical features of magma generation processes.Armenia is situated in the NE part of the Anatolian-Armenian-Iranian plateau, an intensely deformed segment of the Alpine-Himalayan belt. The complex geological structure of the region is represented by a mosaic of tectonic blocks comprising fragments of volcanic arcs, continental crust and exhumed oceanic crust of the Mesozoic Tethys ocean basin (Meliksetian, 2013). The Gegham volcanic upland is located in the center part of the Neogene-Quaternary volcanic belt formed within the territory of the Armenian Highland. The duration of volcanism within the Gegham ridge spans from the Late Miocene to the Holocene (Karakhanyan et al. 2003, Karakhanyan et al. 2002). Temporal and spatial relationships between polygenetic and monogenetic volcanic activity as well as transitions from one to another are among fundamental problems in volcanology. Geological evidence such as presence of thick (abouth 500m) Vokhchaberd volcanoclastic suite at foothills of Gegham volcanic ridge suggests presence of stratovolcano (caldera-?) activity in Late Miocene-Pliocene (K-Ar dating data 3.4-6.7Ma; Bagdasaryan and Ghukasyan 1985) in Gegham, that was switched later to monogenetic activity and crater (or caldera) and slopes of former stratovolcano covered by monogenetic vents and their lava flows. After the polygenic volcanism the volcanism of Gegham upland is accompanied by fissure (plateau basalt) and monogenic volcanism.Plateau basalts of Gegham upland distributed within town Gavar and Kotayk plateau, gorg of Hrazdan river up to village Parakar and age of these are 40Ar/39Ar 2.37±0.03 Ma (Neill et al., 2015). According to K. Karapetyan (1962, 1973) the youngest, Upper Pleistocene-Holocene volcanism of the upland is confined to the watershed part of the upland and the Eratumber plateau. According to Meliksetian (2017), there are data from extended flows from the Gegam upland - Argavand (221.1±5.0 Ka), Gutansar (314.1±16.2 Ka), Garni columnar flow of basaltic trachyandesites (127.7± 2.6 Ka) and lavas overlapping the Garni flow (49.9±9.2 Ka), which show the chronological and stratigraphic position volcanic activity of Gegham upland.Taking into account the available and new reliable data, it is obvious that the volcanism of the Gegham upland continued from the Late Miocene-Early Pliocene time and up to the Upper Pleistocene and Holocene, and at the turn of the Pliocene-Quaternary period, due to changes in volcano-tectonic conditions, a change occurred in polygenic explosive-effusive volcanism to predominantly effusive areal.Geochemical typification of the volcanic series of the Gegham upland indicates the predominance of "subduction" related fingerprints in them, however, some transitional to "intraplate" geochemical features are also found. The geochemical features and the petrogenetic model of the evolution of the volcanic series of the Gegham upland suggest a single magma-generating source and similar conditions for the evolution of melts within the entire Gegham upland.

Armenia is a landlocked country in the South Caucasus region, situated between Iran, Georgia, Azerbaijan and Turkey, with population of about 3.0 million. Since Neogene to Quaternary times, the territory of Armenia has been located in a continent-continent collision zone (i.e., collision of the Arabian and Eurasian plates) and exposed to transpressional tectonics resulting in widespread and long-lasting polygenetic and monogenetic volcanic activity.The studies of spatial density of vents in Armenia (Weller et al., 2018, Sugden et al. 2021) demonstrate that Armenia is one of the densest clusters of Quaternary monogenetic volcanoes on Earth: in total, 516 volcanoes are mapped within the area of ~30,000 km2. Most of the monogenetic volcano clusters are oriented NW to SE, perpendicular to the major stress direction related to the movement of the Arabian plate from SW to NE.Several active faults and potentially active and active volcanic systems exist in the country and many historical earthquakes have been recorded. The geology of Armenia with its volcanoes and active faults being potential source of hazards at the same time, has an important potential for geothermal energy, whilst much of Armenia’s current energy production is from imported fossil and nuclear fuel.It is noteworthy, that hundreds of sources of thermal mineral waters exist in Armenia and most of them are found in close proximity to volcanic systems and active faults. Our preliminary geochemical studies of mineral waters aiming to apply geochemical thermometers to investigate the formation temperature of waters demonstrate several geothermal anomalies in Armenia. This contribution will present unified geological, geophysical, volcanological, geochemical database with selection of promising sites for further studies of geothermal energy potential of Armenia, and some preliminary results of application of ambient noise tomography (ANT) and satellite data.

International audience; Relationships between steppe vegetation, human practices and climate changes in the past are crucial to disentangle human development in Eurasia. In this frame, our study investigates (1) modern pollen-vegetation relationships and (2) changes in vegetation, human activity and climate in the Holocene record of Vanevan peat (south-eastern shore of Lake Sevan, Armenia), using a multiproxy approach including sediment geochemistry (XRF), pollen, Non-Pollen Palynomorphs (NPPs), and branched Glycerol Dialkyl Glycerol Tetraethers (brGDGTs). Climate reconstructions are provided by (1) water-level changes, (2) brGDGTs, and (3) pollen transfer functions (multi-method approach: Modern Analogue Technique, Weighted Averaging Partial Least Squares regression, Random Forest, and Boosted Regression Trees). Modern pollen assemblages are selected along an altitudinal transect in Armenia. They show a dominance of Chenopodiaceae in semi-desert/steppe regions while meadows steppes, subalpine, and alpine meadows are dominated by Poaceae. Past vegetation is characterized by steppes dominated by Poaceae surrounded during the Mid-Holocene (8200-4200 a cal BP) by scarce open woodlands. Humans have influenced the local vegetation, mainly through their agricultural practices present since 5200 a cal BP with several intensification steps. Our reconstruction indicates a climate shift from a cold and arid Early Holocene toward a warmer and more humid Mid-Late Holocene. An aridification trend marks the last 5000 years causing a drop in water level, which allowed humans to live and cultivate on Lake Sevan shores. Arid events are recorded at 6.2 ka, 5.2 ka, 4.2 ka and 2.8 ka a cal BP, which are commonly related to multi-centennial-scale variations of Westerlies activity (North Atlantic Oscillation). Through our temperature reconstruction, we can assign (1) the 5.2 and 2.8 ka events as being cold and probably related to a strong Siberian High, and (2) the 4.2 ka event as being warm associated with high Arabian subtropical pressures in the South Caucasus and the Near East. Our study suggests a significant impact of these arid events on the Lake Sevan shore populations and they are consistent with cultural phases in the South Caucasus, thus showing the impact of climatic variations on cultural, land use and occupation mode development in this crossroad region between Europe, Africa and Asia.

The settlement of Godedzor is located at 1,800 m asl in the region of Syunik (south-eastern Armenia). Previous studies have highlighted the strategic position of the site in connection to both east to west and north to south routes of communication and in relation to the proximity to the main obsidian outcrops of the region. Excavations at Godedzor started in 2005 and revealed three main levels of occupation consisting of wooden and stone architecture. A substantial set of radiocarbon datings proves that the occupation at Godedzor can be dated to the mid 4th millennium and highlights that the site is one of the latest Chalcolithic occupations discovered so far in the southern Caucasus. In this paper, the most recent research on the architectural, ceramic, archeozoological and archeobotanical evidence from Godedzor is analysed and combined so as to build a comprehensive picture on the strategies of the pastoral groups that occupied Godedzor, on their origins and finally on the role that these groups played in the circulation of the obsidian in north-western Iran and in the introduction of farming practices in the highlands of southern Armenia. L’établissement de Godedzor est situé à 1 800 m d’altitude dans la région du Syunik (sud-est de l’Arménie). Les études précédentes avaient souligné l’implantation stratégique de ce site au cœur d’un réseau de voies de communication est-ouest et nord-sud, à proximité des principaux gisements d’obsidienne de la région. Les fouilles de Godedzor, entreprises en 2005, ont révélé trois niveaux d’occupation avec une architecture de bois et de pierre. Un important corpus de datations au radiocarbone montre que l’occupation de Godedzor remonte au milieu du IVe millénaire et met en évidence que, parmi les occupations chalcolithiques découvertes à ce jour dans le sud du Caucase, il s’agit d’une des plus tardives. Dans cet article, les recherches récentes sur les vestiges architecturaux, la production céramique, les données archéozoologiques et archéobotaniques de Godedzor sont analysées et synthétisées dans le but d’obtenir une vue d’ensemble des stratégies des groupes pastoraux qui ont occupé ce site, de leur provenance, ainsi que de leur rôle dans la circulation de l’obsidienne vers le nord-ouest de l’Iran et dans l’introduction des pratiques agricoles sur les hautes terres du sud de l’Arménie.

Purpose The purpose of this paper is to discuss how, despite increasing data availability from a wide range of sources unlocks unprecedented opportunities for disaster risk reduction, data interoperability remains a challenge due to a number of barriers. As a first step to enhancing data interoperability for disaster risk reduction is to identify major barriers, this paper presents a case study on data interoperability in disaster risk reduction in Europe, linking current barriers to the regional initiative of the European Science and Technology Advisory Group. Design/methodology/approach In support of Priority 2 (“Strengthening disaster risk governance to manage disaster risk”) of the Sendai Framework and SDG17 (“Partnerships for the goals”), this paper presents a case study on barriers to data interoperability in Europe based on a series of reviews, surveys and interviews with National Sendai Focal Points and stakeholders in science and research, governmental agencies, non-governmental organizations and industry. Findings For a number of European countries, there remains a clear imbalance between long-term disaster risk reduction and short-term preparation and the dominant role of emergency relief, response and recovery, pointing to the potential of investments in ex ante measures with better inclusion and exploitation of data. Originality/value Modern society is facing a digital revolution. As highlighted by the International Council of Science and the Committee on Data for Science and Technology, digital technology offers profound opportunities for science to discover unsuspected patterns and relationships in nature and society, on scales from the molecular to the cosmic, from local health systems to global sustainability. It has created the potential for disciplines of science to synergize into a holistic understanding of the complex challenges currently confronting humanity; the Sustainable Development Goals are a direct reflectance of this. Interdisciplinary is obtained with integration of data across relevant disciplines. However, a barrier to realization and exploitation of this potential arises from the incompatible data standards and nomenclatures used in different disciplines. Although the problem has been addressed by several initiatives, the following challenge still remains: to make online data integration a routine.

Large (VEI= 4-6) Quaternary explosive eruptions have repeatedly occurred in Armenia and the neighboring territories. Worth noting are the Plinian eruptions of Aragats stratovolcano (4096m), located in the vicinity of the Armenian capital city Yerevan (pop. >1 million) and producing lava flows variable in composition and size, pyroclastic density currents (PDCs) and fallout deposits (Connor et al., 2011; Gevorgyan et al., 2020). The youngest lavas from Aragats are 0.52 million years (myr) old and the youngest ignimbrites are 0.65 myr old. (Connor et al., 2011, Gevorgyan et al., 2020).Here we present some features of a violent explosive Plinian eruption (VEI=4) from the relatively small, subsidiary Irind vent on the slopes of Aragats stratovolcano. We report results from newly mapped thick pumice fall deposits and pumice-rich welded lapilli-tuff and vitrophyres. Formation of up to ~10 m thick pumice fall deposits is related to a sustained Plinian eruption, while the formation of overlaying pumice tuffs (age= 0.490±0.028 M.yrs, Connor et al., 2011) and vitrophyre cover is interpreted as result of collapse of the eruption column due to a decrease of the magma supply.Following the pyroclastic eruption, a voluminous (2.9-3.6 km3) effusive eruption of Irind created up to 120 m thick trachydacite lava flows that extended 18 km from the vent. Such long and thick lava flows are not typical for viscous felsic lavas. The Irind eruption products are characterized by a plagioclase-two pyroxene mineral association that is atypical for Aragats. The Irind magmas are trachydacitic (SiO2= 66 wt; MgO= 0.7 wt%) with high- K2O contents (5.2 wt%) and enrichments in U, Th, LILE and LREE compared to Aragats. Geothermobarometry and hygrometry based on detailed textural analysis and mineral chemistry (Cpx, Opx, plagioclase, glass) reveals that Irind magmas also have elevated H2O, increased alkalinity and high T (~970 °C)- all features capable to generate magmas with much lower viscosity (4.2–4.5 log η Pa·s) in respect to typical dacites.Our results support the view that often small eruptive vents (Irind) on the slopes of large coeval stratovolcanoes (Aragats) are not necessarily tapping their voluminous magma mushes underneath and are capable to deliver independent Plinian eruptions. We speculate that these are triggered by intrusions of hot, volatile-rich, alkaline felsic magmas, presumably emplaced fast, similar to the Chaiten eruption in 2008, and did not mix well with the otherwise dominant and older magmatic system under Aragats.ReferencesConnor C., Connor L., Halama, R., Meliksetian, K., Savov, I., 2011. Volcanic Hazard Assessment of the Armenia Nuclear Power Plant Site, Final Report, 278 pp.Gevorgyan, H., Breitkreuz, C., Meliksetian, K, et al., 2020. Quaternary ring plain- and valley-confined pyroclastic deposits of Aragats stratovolcano (Lesser Caucasus): Lithofacies, geochronology and eruption history, JVGR 401, 1-22.

This contribution refers to ongoing research project funded by the Government of the Republic of Armenia titled “Geopark as an impetus for sustainable economic development and environmental protection in Gegharkunik and Vayots Dzor Provinces, Armenia” currently implemented by the Institute of Geological Sciences of the Armenian NAS. Tectonically and volcanically active territory of Armenia, located in Arabia-Eurasia continent-continent collision zone, is characterized by a complex geological history and the presence of a mosaic of different geological blocks and terranes, for instance, continental blocks, ophiolites and arcs merged together by long-lasting convergent plate geodynamics. The presence of internationally significant geological sites combined with rich archeological, historical and cultural context strongly supports the idea of establishment of Geopark in Armenia, also taking into account potential economic benefits both at country level and for more than one hundred local communities.The suggested area for the first Armenian Geopark comprises several thousand sq.km, mostly in Gegharkunik and Vayots Dzor provinces. The selected area Geopark is unique also in its diverse mountain landscapes and volcanic landforms. Given the presence of active faults, volcanoes and significant examples of volcano-tectonic interactions, as well as certain well-pronounced evidence of hazardous geological phenomena, such as surface ruptures, Holocene volcanism, tectonically induced landslides, sedimentological and paleontological evidence of past mass extinction events, geothermal activity, etc., it is proposed to establish a Geopark focused on geological hazards.Post-collisional volcanism is one of the key features of geology of Armenia and volcanological geosites play a significant role in the proposed Geopark, particularly, some of Pleistocene-Holocene volcanoes, lava flows, lava tubes, lava falls, crater lakes, as well as thick obsidian flows with records of Paleolithic use and other sites.To date, 40 geosites, classified according to geological phenomena having an international or regional significance, have been selected and documented according to local experience and international approaches. Some of the selected geosites are characterized by a complex geological record, with a long history of research and multidisciplinary studies.The proposed Armenian Geopark aims at wider sharing of the accumulated geological knowledge with society and attracting tourists as a factor of sustainable development. It is suggested that the establishment of Geopark in Armenia will strongly support the protection of rich geological heritage and geoconservation, contributing to sustainable management of protected areas and spreading Earth sciences oriented knowledge and education in Armenia and beyond, in the entire region.

International audience

International audience

Located in the heart of the Lesser Caucasus mountains, where the Arabian and Eurasian tectonic plates collide, Armenia occupies an exceptional geological position shaped through millions of years of subduction and collision. It is a unique place on the Earth recording extensive intrusive and volcanic activity related to the long‐standing continental convergence. The volcanoes of Armenia provide a rare opportunity to study the sources and processes involved in this unusual type of magmatism. More than 500 Quaternary volcanoes have been mapped in Armenia, most of them formed from single eruptive episodes. Among several large composite volcanoes, the mighty Aragats stands out as the largest volcano in Armenia and the region altogether. Volcanic deposits testify to the range of eruptive styles—from the ignimbrites formed in eruptions as explosive and voluminous as any seen globally in the modern era to the enormous fissure‐fed lava flows that form the Southern Caucasus flood basalt province, the smallest and youngest Large Igneous Province in the world. Several pre‐historical and historical eruptions have been documented, highlighting the potential for future volcanic activity in the region. In recent years, research has focused on the volcanic hazards associated with the Armenian Nuclear Power Plant, located in the foothills of Aragats volcano. This article highlights some of the extraordinary volcanic and intrusive features observed in Armenia and summarizes aspects of recent volcanological and petrological research.

The purpose of this paper is to present new data on active geological processes in the Lake Sevan Basin and to show its multidisciplinary aspects. The investigations of its structures, recent lake sediments, and lake floor gas emission allow a better understanding of the history of geological development and the recent tectonic and volcanic activity of the basin. This paper summarizes underwater investigations of active geological features of Lake Sevan, undertaken for the first time in Armenia. More than 30 aligned underwater-source related gas emission points were discovered. The gas contains carbon dioxide of volcanic or volcanogenic-metamorphogenic origin and can be related to unloading of deep fluid systems. This allows defining the Noratus-Kanagegh Fault segment trace below the recent Lake Sevan floor sediments. The discovery of the subaqueous segment of active fault shows the presence of another natural hazard of lake tsunami related to possible future co-seismic rupture. The recent sediments of the northwestern Lake Sevan coastline are sandwiched between two blocky lava flows. The radiocarbon dating of bones of bovine mammals (with entire skull), found ~15 cm from the cover of the lake sediments, suggests that the upper blocky basaltic-andesite layer can be a result of eruption younger than ~3400 years BP. About 80 m of the Noratus sequence sediments have been sampled for palaeomagnetic study and the age of 3.1–2.3 Ma for the lower part (42 m) is obtained. The upper and post-Gelasian activity of the Noratus-Kanagegh Fault is proven by a cross-cutscoria layer of 2.30 ±0.15 Ma K/Ar age

Alkaline igneous rocks are relatively rare in settings of tectonic convergence and little is known about their petrogenesis in these settings. This study aims to contribute to a better understanding of the formation of alkaline igneous rocks by an investigation of the Tezhsar volcano-intrusive alkaline ring complex (TAC) in the Armenian Lesser Caucasus, which is located between the converging Eurasian and Arabian plates. We present new petrological, geochemical and Sr-Nd isotope data for the TAC to constrain magma genesis and magma source characteristics. Moreover, we provide a new 40Ar/39Ar age of 41.0±0.5 Ma on amphibole from a nepheline syenite that is integrated into the regional context of ongoing regional convergence and widespread magmatism. The TAC is spatially concentric and measures ~10 km in diameter representing the relatively shallow plumbing system of a major stratovolcano juxtaposed by ring faulting with its extrusive products. The plutonic units comprise syenites and nepheline syenites, whereas the extrusive units are dominated by trachytic-phonolitic rocks. The characteristic feature of the TAC is the development of pseudomorphs after leucite in all types of the volcanic, subvolcanic and intrusive alkaline rocks.\ud 40 Whole-rock major element data show a metaluminous (Alkalinity Index = 0-0.1), alkalic and silica-undersaturated (Feldspathoid Silica-Saturation Index

Quaternary eruptions from an intraplate multistage magma reservoir of the Aragats stratovolcano in western Armenia formed pyroclastic density currents and fallouts deposited in an area around 2,000 km2, comprising six ignimbrite units and three fallout deposits. Published K/Ar and Ar/Ar age data allow for a distinction between older (Calabrian, 1.8–0.90 Ma) and younger (Middle Pleistocene, 0.75–0.65 Ma) ignimbrites. The detailed characterization of the crystal-poor to crystal-rich, trachyandesitic to rhyolitic ignimbrite sequence deciphers the pre-eruptive magmatic conditions. It also contributes to the understanding of Plinian eruptions of the largest volcanic complex in the Lesser Caucasus. The chemical variation of pumice fragments reveals the conditions of both, homogeneous and mingled heterogeneous magma systems. The phenocryst assemblage of the older crystal-poor units (Ab-rich plagioclase + amphibole ± pyroxene) indicates growth in a cooler hydrous magma chamber, whereas the partially resorbed phenocrysts of the younger crystal-rich units (An- to Ab-rich plagioclase + pyroxene) suggest growth in a superheated magma chamber fueled by mafic, mantle-derived melts. In the younger units, external (e.g. sieve fabrics) and internal phenocryst textures have been generated by decompression and convection during ascent. With the older units, the chemical variation in amphibole from core to the narrow break-down rim reveals magma ascent from a deep (13 km depth) to a shallow (up to 8 km) level. Tracking the p-T paths of cumulate fragments (pyroxene, plagioclase) in the younger units, we estimate the depth of the anhydrous crystal-rich magmatic chamber at around 25 km. Based on the composition of clinopyroxene cumulates, we propose a multi-stage evolution of melts from subalkaline and tholeiitic to calc-alkaline composition. The pronounced high Zr content and Zr/Hf ratios of the entire Upper Pliocene to Quaternary post-collisional magmatism could be attributed to partial melting of an enriched mantle source in the Lesser Caucasus.

Quaternary volcanic centres north of the Bitlis-Zagros suture in Turkey, Iran and the Caucasus represent both volcanic hazards and potential or actual geothermal energy resources. Such challenges and opportunities cannot be fully quantified without understanding these volcanoes’ petrogenesis, geochronology and magmatic, tectonic or other eruption triggers. In this preliminary study, we discuss the age and geology of the Karkar monogenetic volcanic field in Syunik, SE Armenia. The ~70 km2 field is close to Armenia’s only geothermal energy test drilling site. Fissure-fed trachybasaltic andesite to trachyandesite lavas erupted on a trans-tensional segment of the Syunik branch of the Pambak-Sevan-Syunik Fault, where previous studies suggested a Holocene age for the youngest eruptions. Here, high-resolution duplicate 40Ar/39Ar dating of 7 groundmass separates provided composite plateau or inverse isochron ages ranging from 6 ± 3 ka and 8 ± 3 ka to 332 ± 9 ka (2). Each lava flow displays petrographic and whole rock geochemical patterns consistent with melting of subduction-modified lithospheric mantle and extensive evolution within the crust involving fractional crystallisation and mixing of magma batches. Data confirm that volcanic activity in Syunik and also Vardenis provinces overlapped with Palaeolithic to Bronze Age human occupation and remains a minor lava inundation hazard. Further geochemical work will allow constraint of the depth and timescales of magma storage. Both Karkar and the area around Porak volcano, which lies 35 km N of Karkar on the Syunik Fault, might be considered for future geothermal energy developments.

Argon isotopic analyses were funded by NERC grant to I. Savov, IP-1690-1116. PJS was funded through a NERC studentship as part of the Leeds York Spheres Doctoral Training Partnership (DTP) (grant number NE/L002574/1). Part of the field work and research were supported by base funding of the Institute of Geological Sciences (IGS) and a thematic project by the Science Committee of the Armenian Ministry of Education and Science (project #18 T-1E368). The post-collisional Syunik and Vardenis volcanic highlands, located in the southern Lesser Caucasus mountains (part of the Arabia-Eurasia collision zone) are host to over 200 monogenetic volcanoes, as well as 2 large Quaternary polygenetic volcanoes in the Syunik highland. The latter are overlain by lavas from the monogenetic volcanoes, suggesting there was a transition in the style of volcanic activity from large-volume central vent eruptions to dispersed small-volume eruptions. 12 new high quality 40Ar/39Ar ages are presented here, with 11 ages calculated by step-heating experiments on groundmass separates, and the final age obtained from total fusions of a population of sanidines. All the ages were younger than 1.5 Ma, except for one ignimbrite deposit whose sanidines gave an age of 6 Ma. While the bulk of the exposed products of post-collisional volcanism relate to Pleistocene activity, it is clear there has been active volcanism in the region since at least the late Miocene. All ages for monogenetic volcanoes in the Syunik highland are younger than 1 Ma, but to the north in Vardenis there is geochronological evidence of monogenetic volcanism at 1.4 and 1.3 Ma. An age of 1.3 Ma is determined for a lava flow from one of the polygenetic volcanoes- Tskhouk, and when combined with other ages helps constrain the timing of the polygenetic to monogenetic transition to around 1 Ma. The new ages illustrate a degree of spatio-temporal coupling in the formation of new vents, which could be related to pull-apart basins focussing ascending magmas. This coupling means that future eruptions are particularly likely to occur close to the sites of the most recent Holocene activity. The polygenetic to monogenetic transition is argued to be the result of a decreasing magma supply based on: (i) volume estimates for Holocene eruptions and for all monogenetic volcanoes and their lava flows in Syunik; and (ii) the volcanic stratigraphy of the Lesser Caucasus region which shows late Pliocene- early Pleistocene continental flood basalts being succeeded by a few large andesite-dacite volcanoes and then the most recent deposits consisting of small-volume scoria cones. The Syunik highland has the highest density of monogenetic centres in the Lesser Caucasus, which is taken to indicate this region has the highest magma flux, and was therefore the last location to transition to monogenetic volcanism, which is why the transition is most clearly seen there. There is no evidence from Sr-Nd-B isotope measurements for the exhaustion of fusible slab components in the mantle source, showing that an inherited slab signature can survive for millions of years after the end of subduction. Although volcanism in the Lesser Caucasus is currently waning, a future pulse of activity is possible. Publisher PDF

Current loess research indicates a better understanding of the factors that determine the ways that loess (dust) accumulation and soil formation has responded to the rapid and variable Late Quaternary climatic changes across Europe and Western Asia. Lack of evidence of loess in the region between the Black Sea and Caspian Sea creates a critical gap in the geographical distribution of this deposit and hence inhibits our ability to examine properly the spatial distribution and processes of formation. The recent discovery of loess-palaeosol sequences in Armenia allows us to overcome this problem and preliminary investigations have yielded encouraging results. A research programme has been established to characterise, analyse and date sequences from NE-Armenia that are up to 45 m thick. This paper presents first results of this study and reports three well-developed pedocomplexes below a Holocene soil. The magnetic properties of the loess indicate mainly Caucasian sources and all palaeosols exhibit clear magnetic enhancement. Luminescence dating of the upper part of the sequences identifies deposition between 150 and 39 ka. During that period, loess deposition took place during MIS 6/4 and 3. A multiphase pedocomplex that documents progressive climate transition from initially humid to arid conditions, could be placed into MIS 5, although we found striking temporal offset between the phase of most intense soil formation and the Last Interglacial climatic optimum. Furthermore, colluvial slope deposits and erosional discordances provide information on distinct phases of landscape instability that are linked to interglacial periods and the transition to glacial conditions.

Aragats stratovolcano, located on the South Armenian block, a micro-plate in the Arabian-Eurasian collision zone, has a complex and long-lasting Quaternary eruption history. Cataclysmic eruptions formed widespread pyroclastic deposits, which are interrupted by numerous basaltic to trachytic lava flows as well as lacustrine and lacustrine-alluvial sediments. Contrary to previous concepts, detailed mapping of lithofacies variation combined with stratigraphic documentation and new high-precision 40Ar/39Ar ages revealed four eruption cycles, each started with mafic lavas and generally finalized with pyroclastic deposits. These data contributed to a fundamental reinterpretation of the development of the Aragats Volcanic Province (AVP). Within an estimated activity of one million years, Aragats itself experienced three eruption stages, two of which culminated in pyroclastic deposits of remarkable lithofacies variability with ages of 0.97 to 0.90 Ma and 0.75 to 0.65 Ma, respectively. Vertical and lateral changes in proximal and distal facies distribution of pyroclastic flow deposits indicate temporal variations in eruption intensity and periods of relative volcanic quiescence. Aragats' explosive activities were dominated by Plinian eruptions with columns as high as 25 km, while others are characterized by low eruption columns followed by instantaneous collapse, in one case associated with vent widening, possible caldera collapse and breccia formation. Furthermore, one AVP unit features juvenile lapilli and blocks including banded and armored pumice, indicating magma mingling and their involvement in the erupting mixture before magma fragmentation.

Voluminous early to middle Pleistocene pyroclastic flow deposits were generated from Mount Aragats (Aragats Volcanic Province, AVP), one of the largest volcanoes in the Arabia-Eurasia continental collision zone. Here we report paleomagnetic results, in combination with anisotropy of magnetic susceptibility (AMS) analysis, from 31 outcrops belonging to six ignimbrite units of the western part of the AVP (covering an area of more than 5000 km2). Paleomagnetic directions analysis of samples from 26 outcrops of the three younger ignimbrite units yields a well-defined normal polarity direction of D = 339.2°, I = 55.7°, k = 278.4 and α95 = 1.7°. The virtual coincidence of the paleomagnetic directions seems to point to an emplacement of the units within a restricted time of similar geomagnetic secular variation (i.e., few hundred years). However, new isotope 40Ar/39Ar ages of the three units suggest two separated events at ~0.65 and ~ 0.75 Ma. We cannot fully exclude the possibility of similar paleomagnetic directions at 0.65 and 0.75 Ma or the occurrence of a widespread remagnetization event at 0.65 Ma, but both scenarios are highly unlikely. In contrast to that, five sites from the three older units all show reversed magnetic polarity, which implies an age of emplacement older than the last magnetic polarity reversal at ~780 ka. This agrees with recent 40Ar/39Ar ages of the three older units at ~0.93 Ma. The paleomagnetic scatter of the older units is high compared to the younger ones. Even if paleomagnetic directions and radiometric age are similar, available data cannot unequivocally indicate if the three older units were generated from the same or three different eruptions. The high quality AMS data result in three different types of fabric (lineated, foliated and undetermined) that are all commonly observed in the studied pyroclastic deposits. Accordingly, we use lineation, tilt of foliation, or both for the determination of paleoflow direction. Results reveal a radial flow pattern surrounding Mt. Aragats, which is, however, highly influenced by topographic features, such as valleys, even in proximity of the eruption center.

The Lesser Caucasus mountains sit on a transition within the Arabia-Eurasia collision zone between very thin lithosphere (< 100 km) to the west, under Eastern Anatolia, and a very thick lithospheric root (up to 200 km) in the east, under western Iran. A transect of volcanic highlands running from north-west to south-east in the Lesser Caucasus allows us to look at the effects of lithosphere thickness variations on the geochemistry of volcanic rocks in this continental collision zone. Volcanic rocks from across the region show a wide compositional range from basanites to rhyolites, and have arc-like geochemical characteristics, typified by ubiquitous negative Nb-Ta anomalies. Magmatic rocks from the south-east, where the lithosphere is thought to be thicker, are more enriched in incompatible trace elements, especially the light rare earth elements, Sr and P. They also have more radiogenic 87Sr/86Sr, and less radiogenic 143Nd/144Nd. Across the region, there is no correlation between SiO2 content and Sr-Nd isotope ratios, revealing a lack of crustal contamination. Instead, “spiky” mid-ocean-ridge basalt normalised trace element patterns are the result of derivation from a subduction-modified mantle source, which likely inherited its subduction component from subduction of the Tethys Ocean prior to the onset of continent-continent collision in the late Miocene. In addition to the more isotopically enriched mantle source, modelling of non-modal batch melting suggests lower degrees of melting and the involvement of garnet as a residual phase in the south-east. Melt thermobarometry calculations based on bulk-rock major elements confirm that melting in the south-east must occur at greater depths in the mantle. Temperatures of melting below 1200 °C, along with the subduction-modified source, suggest that melting occurred within the lithosphere. It is proposed that in the Northern Lesser Caucasus this melting occurs close to the base of the very thin lithosphere (at a depth of ∼45 km) as a result of small-scale delamination. A striking similarity between the conditions of melting in north-west Iran and the southern Lesser Caucasus (two regions between which the difference in lithosphere thickness is ∼ 100 km) suggests a common mechanism of melt generation in the mid-lithosphere (∼ 75 km). The southern Lesser Caucasus magmas result from mixing between partial melts of deep lithosphere (∼ 120 km in the south) and mid-lithosphere sources to give a composition intermediate between magmas from the northern Lesser Caucasus and north-west Iran. The mid-lithosphere magma source has a distinct composition compared to the base of the lithosphere, which is argued to be the result of the increased retention of metasomatic components in phases such as apatite and amphibole, which are stabilized by lower temperatures prior to magma generation.

This work was supported as part of Patrick Sugden's PhD studentship funded through the Leeds-York SPHERES NERC doctoral training partnership (NE/L002754/1). Part of the fieldwork and research was funded by the University of Leeds, the Carnegie Institution of Washington, the ERASMUS exchange programme (for IS) and the Science Committee of the Armenian Ministry of Education and Science (project #18T-1E368). The majority of the B isotope analytical work was supported by IGG-CNR funds P1600514. We present the first boron abundance and δ11B data for young (1.5-0 Ma) volcanic rocks formed in an active continent-continent collision zone. The δ11B of post-collisional volcanic rocks (−5 to +2‰) from the Armenian sector of the Arabia-Eurasia collision zone are heavier than mid-ocean ridge basalts (MORB), confirming trace element and isotope evidence for their derivation from a subduction-modified mantle source. Based on the low B/Nb (0.03-0.25 vs 0.2-90 in arc magmas), as well as low Ba/Th and Pb/Ce, this source records a subduction signature which is presently fluid-mobile element depleted relative to most arc settings. The heavier than MORB δ11B of post-collision volcanic rocks argues against derivation of their subduction signature from a stalled slab, which would be expected to produce a component with a lighter than MORB B, due to previous fluid depletion. Instead, the similarity of δ11B in Plio-Pleistocene post-collision to 41 Ma alkaline igneous rocks also from Armenia (and also presented in this study), suggests that the subduction signature is inherited from Mesozoic-Paleogene subduction of Neotethys oceanic slabs. The slab component is then stored in the mantle lithosphere in amphibole, which is consistent with the low [B] in both Armenian volcanic rocks and metasomatic amphibole in mantle xenoliths. Based on trace element and radiogenic isotope systematics, this slab component is thought to be dominated by sediment melts (or supercritical fluids). Previously published δ11B of metasediments suggests a sediment-derived metasomatic agent could produce the B isotope composition observed in Armenian volcanic rocks. The lack of evidence for aqueous fluids preserved over the 40 Myr since initial collision supports observations that this latter component is transitory, while the lifetime of sediment melts/supercritical fluids can be extended to >40 Myr. Publisher PDF

In obsidian-rich Armenia, one of the most archaeologically significant obsidian resources is the Gutansar volcanic complex (GVC). Numerous Palaeolithic sites across Armenia consist of little more than deposits of obsidian tools and debris, and within the Hrazdan Gorge, the vast majority of artifacts is crafted from GVC obsidian. For example, about 93% of the lithic assemblages from the Lower Palaeolithic site of Nor Geghi 1 and the Middle Palaeolithic site of Lusakert Cave 1 are GVC obsidian. Although erupted from multiple volcanic centers, GVC obsidians are geochemically identical and cover an area more than 70 km2. For studies seeking to reconstruct movements of Palaeolithic hunter-gatherers throughout the local landscape, the expansive GVC is problematic: geochemically identical obsidians dominate the foraging territories of sites within and near the complex. Here we explore the potential of obsidian magnetic properties to reveal hitherto unobservable patterns in GVC obsidian utilization with the ultimate goal of elucidating Palaeolithic behavioral patterns. Our results show that magnetic properties vary over multiple scales within the GVC, allowing obsidian sourcing to become multiscalar. These measurements are rapid, inexpensive, and entirely nondestructive for small artifacts. Measuring a few basic magnetic properties enables us to distinguish geochemically identical obsidians from three eruptive centers and potentially to attribute artifacts to specific quarrying sites, recognize changes in provisioning strategy, and estimate a minimum number of cores represented by a lithic scatter.

Armenia has one of the most obsidian-rich natural and cultural landscapes in the world, and the lithic assemblages of numerous Palaeolithic sites are predominantly, if not entirely, composed of obsidian. Recent excavations at the Middle Palaeolithic cave of Lusakert 1 recovered, on average, 470 obsidian artifacts daily. After sourcing more than 1700 artifacts using portable XRF (pXRF) in our field house, our team sought to shift pXRF-based obsidian sourcing into the field itself, believing that the geological origins of artifacts would be useful information to have on-site during an excavation or survey. Despite increasing use of portable instruments, previous studies have principally focused on collections in museums and other archives, and as a result, obsidian sourcing has remained embedded in post-excavation studies. One critical factor in the uptake of obsidian sourcing in the field is the time needed to measure each artifact, frequently 2–6 min in previous studies. Here we report our two methods of obsidian sourcing, including source matching done automatically by the pXRF instrument's onboard software, in only 10 s. Our tests with Armenian geological specimens and Palaeolithic artifacts demonstrate the high efficacy of our two methods, which are sufficiently fast to become syncopated with our excavation and survey activities. By reducing measurement times from a mode of 300 s in recent studies to just 10 s, here we show how (and why) to shift pXRF-based obsidian sourcing from the context of “white lab coats” to that of “muddy boots.”

Late Pliocene to Early Pleistocene (similar to 3.25-2.05 Ma), 200-400 m thick basalt lavas outcrop in the South Caucasus region, including the Kars-Erzurum Plateau (northeastern Turkey), the Javakheti Plateau (Georgia-Armenia), and the Lori Plateau (northern Armenia). These fissure-fed, rapidly erupted fluid lavas filled pre-existing river valleys over many tens of kilometres. The basalts exposed in the Debed River canyon, northern Armenia, are similar to 200 m thick and of three morphological types: (1) basal pillow basalts and hyaloclastites, overlain by (2) columnar-jointed pahoehoe sheet flows, in turn overlain by (3) slabby pahoehoe and rubbly pahoehoe flows. The lower and middle lavas show evidence for damming of river drainage, like many lavas of the Columbia River flood basalt province, Scotland, Ireland, and Iceland. There is also evidence for syn-volcanic faulting of the early lavas. Related basalts also outcrop in the Gegham Uplands and the Hrazdan River basin in Armenia. This 3.25-2.05 Ma South Caucasus basalt province, covering parts of Turkey, Georgia and Armenia, has an estimated areal extent of similar to 15,000 km(2) and volume of similar to 2250 km(3). Because its main geological features are remarkably like those of many continental flood basalt (CFB) provinces, we consider it a true, albeit small, CFB province. It is the smallest and youngest CFB in the world. An analogue closely similar in major features is the Late Miocene Altos de Jalisco CFB province in the western Trans-Mexican Volcanic Belt. Both provinces formed during lithospheric pull-apart and transtensional faulting. Their broader significance is in showing flood basalt size distribution to be a continuum without natural breaks, with implications for geodynamic models. (C) 2015 Elsevier B.V. All rights reserved.

Armenia is located in the Caucasus Mountains and today, its vegetation is largely dominated by steppes closely linked with human practices. Armenian human history roots back to the Neolithic period, which questions long human influences on steppe and therefore climate reconstructions from vegetation data. Moreover, vegetation records from this region are often low resolution and do not cover the entire Holocene. Pollen-based climate reconstruction coupled to independent climate reconstructions appear necessary to fully understand climate forcing in the region during the Holocene. In this study, we introduce high-resolution pollen, geochemical analyses and temperature reconstruction based on pollen and branched glycerol dialkyl glycerol tetraethers (brGDGTs) from Vanevan peat in Armenia. The wetland studied show major ecological changes observed through aquatic vegetation and sediment composition (XRF data). At the beginning of the Holocene, the study site is expected to be integrated in a larger Lake Sevan, then it became an independent lake and finally a peatland at 5700 cal BP. A drying phase is also attested around 4.2 kyrs, probably corresponding to the 4.2 ka climate event. Along the sequence, the vegetation is characterized by steppes dominated by Poaceae, Artemisia and Chenopodiaceae. However, forests composed of Quercus, Betula, Carpinus betulus and Ulmus, are more developed on slopes between 7600 cal BP and 5500 cal BP. Agriculture is observed since 5700 cal BP and correlates with occupation periods reported in archeological studies. Over this 10000 yrs-long record, we suppose that differences in response of wetland and vegetation to climate might be linked to ecological processes and human influence. The comparison between pollen-based climate reconstruction and temperature obtained with brGDGT calibrations promisingly illustrate these differences. Finally, we contextualize these results with other regional records to understand the impact of climate change on steppe vegetation in the Caucasus at a larger scale.

Probabilistic modeling of lava flow hazard is a two-stage process. The first step is an estimation of the possible locations of future eruptive vents followed by an estimation of probable areas of inundation by lava flows issuing from these vents. We present a methodology using this two-stage approach to estimate lava flow hazard at a nuclear power plant site near Aragats, a Quaternary volcano in Armenia.