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Coastal areas of the lakes are quite sensitive to climatic, hydrologic, and anthropogenic changes. These areas are also an indicator that reveals the interaction between natural driving forces and anthropogenic factors. Lake Van coastal region is a dynamic area heavily affected by the natural processes and human activities. The present study focuses on coastline evolution and associated driving forces of the Lake Van. Natural driving forces influencing the changes in the coastline were determined as rock type, water-level fluctuations, wave and current action, tectonics, and fluvial-based processes. The eastern coasts of lake are identified as the most intensive region for the erosion and deposition in terms of natural factors. Most of the residents prefer to live in the coastal areas of the Lake Van, likely large percentage of the world's population choice. Coastal settlements and their coastal protection structures such as embankments and harbours negatively affect the natural processes such as erosion, sediment transportation, and deposition. Dams and river reclamation channels in rivers indirectly affect the coastal evolution by reducing the sediment input into the lake. These anthropogenic stressors on coastal evolution completely change the natural balance. Understanding of all these environmental factors is an indicator for the existing circumstances of the Lake Van coastal area and provides wider perspective to assess of protection and management of this area.

Coastal wetlands are in decline globally because of climatic and/or hydrological changes, and anthropogenic activities. Deltaic wetlands are complex environments formed by different water sources, particularly when ionically rich soda water and freshwater and converge and influence the presence and diversity of biological activity. Lake Van is a terminal lake, 1650 meters above the sea level, surrounded by high mountains. Because of its alkaline water, vegetation and biological activity are generally rich in the deltaic areas. In this study, geological evolution of Bendimahi River Delta System, located on northeastern part of the Lake Van, is assessed as to constructive and destructive temporal factors, determined with satellite images and field studies. Bendimahi river channel is significantly deformed by regional tectonic activity and this deformation has caused migration of deltaic wetland. That migration process has resulted in abandoned deltaic area and a new delta formation. Hydrological and biological results of the migration of the Bendimahi River Delta System clearly indicate the importance of wetlands on coastal ecology, especially alkaline lakes.

© 2019 Elsevier B.V.The southern part of the Eastern Anatolian Plateau is a key region for understanding the tectonic activity and related deformation patterns of the Arabian–Eurasian collision zone. The geological record of seismic events collected from lacustrine deposits of Lake Van Basin is a critical requirement for seismic hazard assessment and seismic risk reduction. Our paleoseismic investigations revealed well-preserved seismites at five locations in late Pleistocene lacustrine deposits. The seismites were dated using an optically stimulated luminescence dating method and were arranged according to their ages. Their type, such as convolute, dish-and-pillar, flame, and ball-and-pillow structures, as well as their locations, ages, and stratigraphic distribution enable us to identify the responsible fault and the earthquake recurrence interval. On the basis of these properties, the Erciş Fault has been recognized as the structure responsible for creating the seismites. The time span between the seismites indicates an apparent earthquake recurrence interval of 125–250 years for large earthquakes (M ≥ 5) related to the Erciş Fault. The method applied here enriches our knowledge on the seismic hazards present in the northern Lake Van region.

Western Anatolia hosts many low‐to‐moderate and high‐temperature geothermal sources in which active faults play a dominant role to control the recharge and the discharge of geothermal fluid. In this study, we used the two‐dimensional geoelectric structure of Kutahya Hisarcik geothermal field, and created a conceptual hydrogeophysical model that includes faults, real topographical variations and geological units. The temperature distribution and fluid flow pattern are also investigated. The depth extension of Hisarcik Fault, electrical basement and low resistivity anomalies related to the presence of geothermal fluid are determined by using resistivity studies in the area. Numerical simulations suggest that Hisarcik fault functioning as a fluid conduit primarily enables hot fluid to be transported from depth to the surface. It is shown that the locations of predicted outflow vents coincide with those of hot springs in the area.

Submarine fan deposits which constitute the remnants of Neo-Tethys are widely observed throughout the Bitlis–Zagros Suture Belt. Most of these deposits are located in the Arabian-Eurasian collision zone and have been intensively deformed due to ongoing tectonic activity. In this study, the depositional characteristics and preservation processes of the undeformed, Lower Miocene Gorendagi Submarine Fan deposits, associated with this zone, are studied with respect to their sedimentological and structural features. These deposits display feeder or distributary channels, overbank, and lobe sediments and classical Bouma Ta–d divisions. They are subdivided into inner, middle, and outer fan, according to sedimentological and morphological properties. Sand-rich submarine fan deposits have 39 m thickness and approximately 2 km of lateral extension. The submarine fan body is bounded to the north and the south by two reverse faults, namely the Ozyurt and Goktepe faults. These faults formed an accommodation space where the fan was deposited and also caused the deepening of the basin. The position and activity of these oppositely inclined reverse faults, which form a triangular zone, are the main reason for preservation of the original fan morphology in the Gorendagi Submarine Fan. Our results indicate that the Gorendagi Submarine Fan represents one of the last sequences deposited before the closure of the southern branch of the Neo-Tethys Ocean and also the most well-preserved.

Fluid contribution in a tectonic process is a crucial parameter for characterization of its products. In the geophysical point of view, illustrating the electrical resistivity structure of any tectonic system can be used to determine effects of fluid contribution. Magnetotellurics is globally used to decipher characteristics of fault zones, volcanoes and hydrothermal systems which are related to driving tectonic regime in collision and transition zones. Mt. Erciyes, which is the largest composite volcano of the Central Anatolian Volcanic Province in Turkey, developed in two particular stages during the Quaternary. Igneous activities in Koçdağ and New Erciyes stages created a plausible environment to observe dominant calc-alkaline products while alkaline and tholeiitic components are also present in the region. Geochemical evidences offer that fractional crystallization combined with low degree crustal assimilation were experienced during the formation of the volcano in addition to potential magma mixing processes occurred in the magma chambers. As part of NSF-funded Continental Dynamics/Central Anatolian Tectonics Project (CD/CAT), this study aims to investigate electrical resistivity structure beneath Mt. Erciyes by means of three-dimensional modeling of the wide-band magnetotelluric data collected at 48 sounding locations. Current model depicts a high conductivity anomaly beneath Mt. Erciyes, which corresponds to its hydrothermal system and related clay cap. Within Erciyes pull-apart basin, local branches of Ecemiş Fault Zone that possibly reinforced the convenient setting for the upwelling of volcanic materials, bound the interconnected highly conductive zones in shallow depths. Under these circumstances, a complex resistivity distribution arises as a consequence of various electrical transfer mechanisms contemplated for the study region.

Soft-sediment deformation structures of different types and sizes are frequently observed in the lacustrine deposits of Lake Van. According to sedimentary features and regional factors, these structures are categorized as non-seismic originated and seismically-induced, soft-sediment deformation structures. Well-preserved non-seismic originated, soft-sediment deformation structures were observed in fine-grained sandy and silty deposits at three locations (Catakdibi, Yumrutepe, and Yukanisikli), and occur at different stratigraphic horizons, exhibiting morphological variability as they consist of load, flame, and slump structures. The formation mechanisms of these structures are determined by the characteristics of their sedimentary facies and environmental conditions. Overloading, caused by rapid coarse sediment deposition or underwater landslides, and storm waves are identified as triggering mechanisms, while rapid sediment accumulation and underwater mass movements caused by volcanogenic shakes are the conditions responsible for the formation of non-seismic soft-sediment deformation structures, in terms of regional geodynamics. (C) 2019 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved.

Understanding magmatic systems and deep hydrothermal circulation beneath arc-volcanoes provides insights into deep processes associated with slab-subduction and mantle-wedge partial melting. Here we analyze hydrothermal flow below a structural high (Capo Vaticano Ridge, CVR) located offshore Capo Vaticano (western Calabria) and affected by magmatic intrusions generated from above the Ionian subducting-slab. In order to explain observations, we combine geophysical and numerical modelling results. Fluid-flow modelling shows that temperature distribution and geothermal gradient are controlled mainly by hydrothermal circulation, in turn affected by heat source, fault pattern, rock permeability, basement topography and sediment thickness. Two main faults, shaping the structural high and fracturing intensely the continental crust, enable deep hydrothermal circulation and shallow fluid discharge. Distribution of seismicity at depth supports the hypothesis of a slab below Capo Vaticano, deep enough to enable mantle-wedge partial melting above the subduction zone. Melt migration at shallow levels forms the magmatic intrusions inferred by magnetic anomalies and by δ3He enrichment in the discharged fluids at the CVR summit. Our results add new insights on the southern Tyrrhenian Sea arc-related magmatism and on the Calabrian inner-arc tectonic setting dissected by seismogenic faults able to trigger high-destructive earthquakes.

Many high temperature geothermal fields generally occur at settings of recent active tectonism or volcanism accompanied by the active faults and fractures. It is well known that the structural controls such as topography, active faults, etc., have a major effect on fluid flow pathways in those systems. In this paper, a complete hydro-thermo-geophysical model is created for the first time in the Gediz Graben, Western Anatolia. The finite volume method is used for numerical simulations by implementing a finite volume code, ANSYS-Fluent. The thermal and physical rock properties used in the model are taken from previous studies. Fluid flow velocity vectors and resulted temperature patterns for the region are calculated and presented. Our simulations demonstrate that the low-angle Master Graben Boundary Fault (MGBF) has three dominant roles 1) transporting the meteoric water to the depths; 2) distributing the heated geothermal water into the basin with inner basin faults, 3) transmitting the heated water to the surface. The model in this work can be easily adopted and extended to explore the possible reservoir structures in other geothermal areas.

Coastal environments are exposed to frequent and intense storm events which are one of the most important elements of sedimentation dynamics in nearshore environments. However, lacustrine storm deposits are rare Late Quaternary sediments of the Lake Van Basin, Turkey, which allow to analyse that kind of storm deposits in a closed lacustrine basin. The storm-induced sedimentary structures evaluated in these deposits reflect erosional and depositional storm processes and encompass erosional surfaces, graded bedding, wave-ripple crossbeds, parallel bedding, shell beds and biogenetic escape structures. They are present in both marginal and relatively deeper lacustrine facies. Evaluations of sedimentological and palaeontological features of storm deposits together with modern storm records of the Lake Van indicate intense storm effect on sedimentation.

The northeastern coast of the Lake Van (Eastern Anatolia-Turkey) is exposed to energetic waves, inducing large sediment transport rates. Intense wave activity on coastal environment shows the shaping impact on the shoreline either erosional or depositional processes. Sedimentation is characterized by gravelly beaches, spit formation, and barrier-lagoon complex. Colpan barrier and lagoon complex forming the subject of this study occurred in these swashed environmental conditions. This study aims to introduce formation and evolution of the Colpan barrier and lagoon complex and to assess the future development of the coastal area around the Lake Van. Characteristics of barrier sediments as shape, size, provenance, sedimentary structures, and palaeocurrent directions are determined with field investigations. Smooth, flattened, and rounded polygenetic sediments compose the barrier drifted to the shoreline with coastal processes as wave and longshore currents. Colpan barrier was created a lagoon completely isolated from Lake Van. This wetland constitutes a habitat for some animals and plants with relatively dilute water than sodic Lake Van's. Water level fluctuation is an important element for the constructive and destructive processes for the barrier and lagoon complex.

The Aksu Basin in southern Turkey is dominantly represented by an alluvial fan and five fan deltas (FDs) developed along the tectonically controlled margins of the basin during the Miocene. Four alternating compressional and tensional tectonic phases have influenced the basin since its formation. Strong tectonic movements caused high sedimentation rates and progradation of large debris-flow and mass-flow dominated FDs. Here we describe two FDs (the Karadağ and Kargı FDs) in detail. The Karadağ FD began to develop under the control of a compressional regime and continued the evolution under a tensional regime. The same tensional regime caused the separation of the Karadağ FD from its source and the deposition of the Kargı FD into the newly formed accommodation area. The alternating tectonic regimes and sea-level oscillations in the Aksu Basin gave rise to the development of coral colonies on the shallow delta fronts, forming patch reefs despite the large amounts of conglomerates supplied by fan deltaic processes.

The Aksu Basin, within the Isparta Angle, is located to the north of the intersection of the Aegean and Cyprus arcs and has been evolving since the Middle Miocene. Correlation of: (1) kinematic analysis of fault planes that cut the basin fill, (2) the reactivation/inversion of fault planes and (3) sedimentological data indicate that the Aksu Basin has evolved by four alternating compressional and extensional tectonic phases since its formation. The first phase was NW-SE oriented compression caused by the emplacement of the Lycian Nappe units which ended in Langhian. This compressional phase that induced the formation and the initial deformation of the basin was followed by a NW-SE extensional phase. This tectonic phase prevailed between the Langhian and Messinian and was terminated by a NE-SW compressional regime known as the Aksu Phase. The neotectonic period is characterized by NE-SW extension and began in the Late Pliocene. Correlation with the existing tectonic literature shows that the order of deformational phases proposed in this study might also be valid for the entire Isparta Angle area.

International audience; Fissure-ridge travertines (FRTs) are of great importance for the determination and comparison of tectonic deformation ina region. The coeval development of these travertines with active fault zones supplies significant information aboutregional dynamics in terms of deformation pattern and evolution. In this paper, the characteristics of FRTs of the Başkalebasin (eastern Turkey) and responsible regional tectonism are discussed for the first time. The Başkale basin is locatedbetween the Başkale Fault Zone (BFZ) characterised by Çamlık fault and Işıklı–Ziraniş fault. It is located betweendextral Yüksekova Fault Zone and southern end of dextral Guilato–Siahcheshmeh–Khoy Fault system (Iran). Variousmorphological features indicating recent activity are exposed along the BFZ, including offsetting rivers, fissure-ridgetravertine and fault scarps. The Çamlık fissure-ridge travertine composing of three different depositions is observed alongthe eastern edge of the BFZ with approximately parallel orientations. The Çamlık fissure-ridge travertine has beenformed and developed on fault zone related to strike-slip or oblique movements. We explain how kinematic changes offaults can influence the fissure-ridge development.

The Lake Van Basin, located at the collision zone of the Eurasian and Arabian plates, has great potential in terms of geological heritage. The world's largest soda lake which gives its name to the basin contains magnificent geological structures. Lacustrine deposits of the lake represent important clues about seismic activity during the Late Quaternary in addition to its sedimentological and paleontological background. Seismites-deformational structures which are formed during earthquakes in unconsolidated sediments-are very rare geologic phenomena. These structures, formed by earthquakes of magnitude >= 5 under suitable conditions, provide valuable information about the responsible faults and their seismic repetition frequency for the region. Today, rising awareness of geological heritage is a glimmer of hope for the protection and preservation of these rare structures in the Lake Van Basin for the generations to come. Conservation of these structures will also help the protection of other naturally, historically, and culturally significant geological beauties. The responsibility for the promotion and conservation of these geological heritages should be a mission not only for the hosting country but also for the entire geological community.

Arap ve Avrasya Plakalari arasinda gelisen carpisma, Miyosen ve sonrasinda Van Golu ve cevresinde bircok dag arasi havzanin olusumuna sebep olmustur. Bu havzalardan birisi de Van’in Ozalp ilcesinde bulunan Pliyosen Dorutay Havzasi’dir. Karbonifer yasli metamorfikler ve Kretase ofiyolitlerinden olusan temel kayaclar uzerinde uyumsuz olarak gozlenen Pliyo-Kuvaterner yasli golsel cokeller, bu donemde bolgede bulunan genis yayilimli bir golun varligini isaret etmektedir. Deniz seviyesinden 2060 m yukseklikte ve 150 km2 yayilima sahip olan bu eski golun sinirlari, golsel cokeller icerisindeki kiyi fasiyesleri yardimiyla belirlenmistir. Golsel cokellerin, cokelme alt ortamlarinin ve ortam kosullarinin anlasilmasi icin sedimanter fasiyes ozellikleri incelenmis ve bolgede 8 adet sedimanter fasiyes ile sig gol ve golsel kiyi ortamini temsil eden 2 adet fasiyes birlikteligi ayirt edilmistir. Dorutay Havzasi tektonizmanin oldukca aktif oldugu bir bolgede yer almaktadir. Gerek havza kenarlarinda, gerekse cokel dolgusunda gozlenen faylar, havzanin jeolojik evriminde onemli rol oynamaktadir. Ozellikle bu calismada isimlendirilen Cirakkoy Fayi, bolgenin kapali havzadan acik havza kosullarina gecisinin ana sebebidir. Deprem kayitlari ve jeomorfolojik veriler, havzanin tektonik acidan gunumuzde de aktif oldugunu gostermektedir. Anahtar Kelimeler: Dorutay Havzasi, Dogu Anadolu, fasiyes analizi, golsel cokeller, Ozalp-Van, yapisal jeoloji

The soft sediment deformation structures formed by liquefaction or fluidization in the unconsolidated and cohesionless sediments during deposition or later (Lowe, 1975; Owen, 1996). These structures composed of overpressure of sediments, storm waves, sudden oscillation of groundwater or seismic shakings (Allen, 1982; Owen, 1987, 1996; Molina et al., 1998). All kinds of earthquake induced soft sediment deformation structures are called as “seismite” (Seilacher, 1969). Seismites frequently observed in lacustrine deposits alike other depositional environments (Sims, 1975; Hempton et al., 1983; Seilacher, 1984; Davenport & Ringrose, 1987; Ringrose, 1989; Mohindra & Bagati, 1996; Alfaro et al., 1997; Calvo et al., 1998; Rodriguez-Pascua et al., 2000; Bowman et al., 2004; Neuwerth et al., 2006; Moretti & Sabato, 2007). Seismites can occur with seismic tremor (M≥5) (Fukuoka, 1971; Kuribayashi & Tatsuoka, 1975; Atkinson, 1984; Ambraseys, 1988) and they use for determination of the location and density of seismic activity (Sims, 1975; Weaver, 1976; Hempton et al., 1983; Talwani & Cox, 1985; Scott & Price, 1988; Ringrose, 1989). The purposes of this study are; to determine the types of deformation structures in Lake Van deposits, to interpret the triggering mechanism and to discuss the importance of these structures in regional tectonic.