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https://hdl.handle.net/20.500.12428/2673

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Late Quaternary paleoclimatic and paleoenvironmental changes in the Konya Closed Basin (Konya, Turkey) recorded by geochemical proxies from lacustrine sediments
(Springer Science and Business Media Deutschland GmbH, 2021) Orhan, Hükmü; Delikan, Arif; Demir, Ahmet; Kapan, Sevinç; Olgun, Kemal
The Konya Closed Basin is an important basin in central Turkey, in terms of its geographic position, Quaternary infills, and well-preserved archeological sites. It comprises Quaternary lake marls and other, mainly fine grained, sediments with locally in excess of 400 m. Geochemical data for samples taken from the 7-m-deep Adakale trench from the late Quaternary lacustrine sediments in the Konya Closed Basin are presented and have been used as proxies to elucidate the past climatic changes, weathering regime, redox conditions, and productivity. Climate changes observed in the studied samples for last 50,000 years were represented by oscillations in weathering processes, detrital input, redox conditions, water levels, and paleoproductivity. Geochemical data show that three periods of high detrital input (high Si+Al+K+Ti+Fe, high Ti/Al, Rb/Sr, low Ca and low Si/Ti), four periods of anoxic conditions (low Mn and Th/U and high Ni/Co, Mo/Al and V/Cr), and four periods of higher productivity (high Cu/Al, Ni/Al, Ca/Al, Ba/Al Si/Ti and Ca/Ti) were effective in the study area. These periods are corresponding to climatic changes during last glacial periods, the warm climate of Dansgaard-Oeschger (D/O) events (D/O 2-12) and the cold climate of Heinrich events (H 2-5).
Determining the geochemical characteristics of geothermal resources and generating a geothermal information system of thermal waters in Biga Peninsula, NW Turkey
(Amer Chemical Soc, 2013) Şanlıyüksel Yücel, Deniz; Yücel, Ali Mehmet; Karaca, Zeki; Çetiner, Ziya S.; Erenoğlu, Ramazan Cüneyt; Akçay, Özgün; Kamacı, Celal; Çalışkan, Hidayet
CORRECTION AND DENSIFICATION OF UAS-BASED PHOTOGRAMMETRIC THERMAL POINT CLOUD
(Copernicus Gesellschaft Mbh, 2016) Akçay, Özgün; Erenoğlu, Ramazan Cüneyt; Erenoğlu, Oya
Photogrammetric processing algorithms can suffer problems due to either the initial image quality (noise, low radiometric quality, shadows and so on) or to certain surface materials (shiny or textureless objects). This can result in noisy point clouds and/or difficulties in feature extraction. Specifically, dense point clouds which are generated with photogrammetric method using a lightweight thermal camera, are more noisy and sparse than the point clouds of high-resolution digital camera images. In this paper, new method which produces more reliable and dense thermal point cloud using the sparse thermal point cloud and high resolution digital point cloud was considered. Both thermal and digital images were obtained with UAS (Unmanned Aerial System) based lightweight Optris PI 450 and Canon EOS 605D camera images. Thermal and digital point clouds, and orthophotos were produced using photogrammetric methods. Problematic thermal point cloud was transformed to a high density thermal point cloud using image processing methods such as rasterizing, registering, interpolation and filling. The results showed that the obtained thermal point cloud - up to chosen processing parameters - was 87% more densify than the original point cloud. The second improvement was gained at the height accuracy of the thermal point cloud. New densified point cloud has more consistent elevation model while the original thermal point cloud shows serious deviations from the expected surface model.
Earthquake strategy for sustainable infrastructure in Turkey
(Ice Publishing, 2014) Erenoğlu, Ramazan Cüneyt; Erenoğlu, Oya
The magnitude 7.4 Izmit earthquake in north-west Turkey in 1999 resulted in 17 127 deaths, 43 959 injuries and extensive property and infrastructure damage. The event highlighted a national lack of seismic design and construction codes. After recovering from the initial effects of the Izmit earthquake, work started on a national earthquake strategy and action plan by public organisations, institutions, academics and practitioners. This paper provides an overview of the efforts to date to achieve safe, earthquake-resilient and sustainable urban infrastructure in Turkey.
Biga Yarımadasında Jeodeğerler ve Jeoturizm Potansiyeli
(TMMOB Jeoloji Muhendisleri Odasi, 2018) Çalık, Ayten; Kapan, Sevinç; Erenoğlu, Ramazan Cüneyt; Erenoğlu, Oya; Yaşar, Cumali; Ulugergerli, Emin Uğur
It is summarized what needs to be done and to be able to utilise three structurally different geological formations within the Canakkale province as geo-parks or geovalue that can attract geologically important and interestingtosocieties. As examples, hot water springs of Tuzla geothermalarea, ancient granite columns of Kestanbolu-Yahya Cavusvillage and opal pit of Yenice village are taken as examples. It is also emphasized that besides the areas highlighted, all other possible areas have their own specific conditions and that ignoring these conditions may cause permanent damages to the area. Earth science museum are also important institutions that will contribute to the discovery and introduction of these fields. As a way of preserving areas that are both scientific and tourist attraction, we have also listed our views on the importance of opening up and exploring to public and the negativity of this activity. According to the first results, while the Tuzla Geothermal field could be used with a few simple arrangements but Kestanbol and Yahya Cavus villages could not be used for the purpose of geotourism with its current state of the fields.
Biostratigraphy of the Paratethyan Neogene at Yalova (Izmit-Province, NW-Turkey)
(Gebruder Borntraeger, 2006) Rueckert-Uelkuemen, Neriman; Kowalke, Thorsten; Matzke-Karasz, Renate; Witt, Wolfgang; Yiğitbaş, Erdinç
Two main palaeoenvironments are reconstructed for the Paratethyan deposits at Yalova (Turkey). The investigated sections show the typical lithologic composition of the Neogene of NW Turkey, however, the palaeoecological context was so far unknown and the stratigraphic differentiation was still outstanding. In this study, molluscs, ostracods and fish remains are used as tools for the interpretations of the palaeoenvironmental situation. These biota reflect palaeoenvironments, represented by (1) the clastic section of the Kilic Formation and (2) the Yalakdere Formation, which is characterized by marl, clay and coal sedimentation. While the Kilic Formation comprises sediments of fluviatile deltaic systems, connected to lagoons with partly reduced water energy, the Yalakdere Formation exemplifies freshwater habitat, including stagnant water bodies with a seasonally slightly varying salinity and, at most, moderately flowing rivers. The investigated biota indicate a Late Miocene age of both the Kilic and the Yalakdere Formation. Some species furthermore allow a more detailed stratigraphic assignment: the Yalakdere Formation corresponds to the Late Khersonian/Early Maeotian. Comparisons with contemporaneous faunas indicate connections to the Dacian, Euxinian and Caspian Basins and a weak Mediterranean influence. No occurrences of Central Paratethyan elements of the corresponding Late Pannonian time interval are evident.
İHA Destekli Dijital ve Termal Kamera Görüntülerine Dayalı Jeotermal Analiz Yöntemleri
(2015) Akçay, Özgün; Erenoğlu, Ramazan Cüneyt; Yılmaztürk, Ferruh; Karaca, Zeki; Erenoğlu, Oya
Combined Use of Standard Penetration Test and Shear Wave Velocities in Liquefaction Analysis: Çanakkale Example
(Springer Science and Business Media Deutschland GmbH, 2023) Eyisüren, Onur; Karaca, Öznur; Büyüksaraç, Aydın; Işık, Ercan
In order to investigate the liquefaction potential of the Çanakkale residential area, 151 boreholes, SPT, and 1027 classification tests were performed on disturbed samples, and 110 units of shear wave velocity (Vs) were determined by multi-channel analysis (MASW) of surface waves, and Vs values determined by underground water level information is used. Unlike previous studies, which were made using the simplified method based on SPT-N, liquefaction potential index (IL) and liquefaction risk index (IR) maps based on the standard penetration test (SPT) as well as Vs parameters were created separately for the Çanakkale settlement area. Very high IL and IR values were obtained in most of the city centers around Sarıçay. At the same time, analyses were repeated for different energy levels in order to investigate the effect of the energy coefficient, which is one of the SPT numbers of impact correction factors, on the analysis. As a result of all the analyses, it is thought that the energy level transferred in the SPT significantly affects the results, and since shear wave velocity (Vs) does not require such a correction, using SPT-N values as a reference in the analyses will reduce the negative effects that may arise from the uncertainties in field tests.
Tectonics of eastern anatolian plateau: Final stages of collisional orogeny in Anatolia
(Wiley, 2023) Yılmaz, Yücel; Çemen, İbrahim; Yiğitbaş, Erdinç
The East Anatolian High Plateau, which is a part of the Alpine-Himalayan orogen, is a 200 km wide, approximately east-west trending belt surrounded by two peripheral mountains of the Anatolian Peninsula. The plateau is covered by thick, interbedded Neogene volcanic and sedimentary rocks. Outcrops of the underlying rocks are rare and, therefore, contrasting views were proposed on the nature of the basement rocks. New geological and geophysical data suggest the presence of an ophiolitic melange-accretionary complex under cover rocks of Eastern Anatolia. The Neogene cover units began to be deposited during the closure of the NeoTethyan Ocean that was located between the Pontide arc to the north, and the continental slivers drifted away from the Arabian Plate to the south. The bordering orogenic belts, the Pontides in the north, and the Bitlis-Zagros Mountains in the south have undergone entirely different evolution. The Eastern Anatolian orogen was formed during the later stages of the development of the surrounding orogenic belts. In this period, the melange-accretionary prism that occupied a large terrain behaved like a wide and thick cushion, which did not allow a head-on collision of the bordering continents. The NeoTethyan oceanic lithosphere was eliminated from the entire eastern Anatolia by northward subduction that lasted till the Late Eocene. The Eastern Anatolia began to rise when the northern advance of the Arabian Plate continued after the total demise of the oceanic lithosphere. The present stage of the elevation of the East Anatolian Plateau as a coherent block started during the Late Miocene.
Bedrock Depth Calculation of Çanakkale (Turkey) Basin Using Rayleigh Ellipticity and Microgravity Survey
(Universidad Nacional Autonoma de Mexico, 2023) Büyüksaraç, Aydın; Eyisüren, Onur; Bektaş, Özcan; Karaca, Öznur
It is a well-known fact that the local ground effect plays an important role in the damage to structures during earthquakes. In order to define the soil-structure interaction correctly, the geometry of the tight and loose soil layers in the soil should be well known. In addition, the impedance contrast due to local ground effects can be deeper than the first 30 m, which is accepted as the engineering depth, and in this case, the Vs,30 parameter is disabled. For this reason, the location of engineering bedrock and seismic bedrock gains importance. The variation of shear wave velocity with depth is a key parameter for seismic field effect estimation. In addition, the separation of low-density layers close to the surface and higher-density bedrock can be easily done by the gravity method. Bedrock/seismic foundation levels were determined by using these two methods together for canakkale soils, which are known to have thick alluvial thickness and liquefaction problems. Microgravity measurements were made at 100 points and the anomalies obtained were modelled in three dimensions. In light of the data obtained from this study, it has been determined that the thickness of the loose basin unit in the study area is in the range of about 50-300 m. Ambient vibration was recorded with the help of a velocity seismometer at 146 points, and S velocity (Vs) profiles were obtained by using the inversion of the observed ellipticity curve. In addition, the velocity-depth change rate structure of the basin is defined depending on the Vs velocities on the 2D gravity model made along the two profiles that cut the basin in N-S and E-W directions. Along these profiles, the frequency range has been determined as 0.8-1.3 Hz in the deep parts of the Basin and 1.5-11.0 Hz in the shallow parts.
Tectonic development of the Ankara-Erzincan suture and the Eastern Pontide mountains, Northeast Anatolia, Turkey
(Taylor and Francis Ltd., 2023) Yılmaz, Yücel; Yiğitbaş, Erdinç
The Eastern Pontides are the northeasternmost component of the Anatolian orogen. Its geological development is closely associated with the evolution of the Ankara-Erzincan Suture. It exhibits records of the events from the opening to the elimination of the surrounding oceans. During the Late Palaeozoic, the Pontides were located in north of Gondwana, facing the Palaeo-Tethys Ocean. The southward subduction of the Palaeo Tethyan oceanic lithosphere generated an active continental margin and opening of the Neo-Tethys Ocean as a back-arc basin during the Early Mesozoic. Throughout the Jurassic-Early Cretaceous, the Pontides remained a passive continental margin facing the Neo-Tethys in the south. Arc reversal occurred as the Neo-Tethys began subducting under the Pontides during the late Early Cretaceous (?)-Late Cretaceous. The Pontides experienced four collisional events throughout the development of the Ankara-Erzincan Suture; (1)- a forearc-arc collision occurred when the accretionary complex, which formed along the southern edge of the Pontides was backthrust over its leading edge during the Late Campanian. (2)- This was followed by a continent-arc collision when the Kırşehir Massif and the underlying NeoTethyan ophiolite nappe collided with and thrust over the Pontides at the end of the Early Eocene. (3)- Following the oceanic lithosphere’s total demise, the remnant basin survived above the remaining part of the accretionary complex located between the Pontides, and the Taurus was closed under the northerly advancing Taurus nappes during the Late Eocene. The latest collision (4) is the collision of the Arabian Plate with the Anatolian plates. The Arabian Plate’s continuing northward advance after the demise of the NeoTethyan Ocean squeezed and shortened Eastern Anatolia. From this time onward, the Eastern Pontides were thrust to the north and the south over the surrounding tectonic belts and started to rise as a coherent block.
Relationship of petrographic and mineralogical characteristics with mechanical strength properties of granitic rocks: a case study from the Biga Peninsula, NW Turkey
(TUBITAK, 2023) Eroğlu, Güven; Çalık, Ayten
This study was carried out on granitic rocks from the Biga Peninsula in order to investigate petrographic, and mineralogical properties in comparison with mechanical strength properties. This study was conducted in four different locations where granitic rocks outcrop from north to south in the Biga Peninsula: Lapseki (Şevketiye granite), Ezine (Kestanbol granite), Bayramiç (Yassıbağ granite), and Edremit (Eybek granite). Field observations and detailed petrographic studies of representative samples indicate that they are quartz monzodiorite (Şevketiye and Yassıbağ), quartz monzonite (Kestanbol), and granodiorite (Eybek) in composition. All the rocks have similar mineral composition, comprising mainly feldspar (plagioclase–alkali feldspar), quartz, mafic minerals (biotite and amphibole), accessory minerals (sphene, zircon, opaque minerals), and secondary minerals (sericite, epidote, chlorite) with differences in the percentage of modal mineralogy, textural details, and weathering. Physical and mechanical properties were also defined in this study, these include water absorption, porosity, uniaxial compressive strength (UCS), tensile strength (TS), Schmidt hardness tests (SHT), Los Angeles test (LA), and frost resistance test (FRT) with sodium sulfate (Na2 SO4 ). The results of strength tests show that the Şevketiye granite had the lowest strength values with the highest values for Los Angeles abrasion, frost resistance, water absorption, and porosity. The Eybek granite exhibited the highest value for strength, with the lowest values for Los Angeles abrasion, frost resistance, water absorption, and porosity. A comparison of the petrographic properties of all studied rocks with their respective strengths show that modal mineralogy, degree of alteration, and texture influence the strength of the rocks. Additionally, an increasing propensity for UCS and TS values was found with increasing SHT values. The LA abrasion values and the FRT values were found to increase with decreasing Schmidt hardness test values for the tested samples. The found results of this study could help in the application of these rocks as row material.
Paleoseismology of the Surgu and cardak faults-splays of the Eastern Anatolian Fault Zone, Turkiye
(TUBITAK, 2023) Balkaya, Musa; Akyüz, Hüsnü Serdar; Özden, Süha
The sinistral East Anatolian Fault Zone (EAFZ) and the dextral North Anatolian Fault Zone (NAFZ) are two important strike-slip faults that delimit the boundaries of the Anatolian plate. The north-south directed compressional forces in eastern Türkiye trigger the westward escape of the Anatolian plate along these prominent structures. This study aims to reveal the earthquake history of the Sürgü and Çardak faults, which are important fault segments that splay from the EAFZ. In this context, overall, four paleoseismologic trenches were dug, two trenches on the Sürgü Fault and two trenches on the Çardak Fault. Along the Sürgü Fault, at least two paleoearthquake events have been determined on the trench walls, one event occurred around 3400 BCE and the second event happened between 2085 ± 65 BCE and 790 ± 20 BCE. Moreover, trenching results from the Çardak Fault indicate two surface rupturing paleoearthquakes between 10520 ± 95 BCE and 5780 ± 65 BCE, and between 3215 ± 125 BCE and 825 ± 55 CE, respectively. The focal mechanisms of important instrumental earthquakes around the Sürgü and Çardak faults on the EAFZ show that NNE-SSW trending compressional forces are actively dominating the tectonic setting of the region in the contemporary era. Paleoseismological investigations suggested that the Sürgü and Çardak faults have the potential to produce surface-rupturing earthquakes with an estimated magnitude of 7 or larger.
Tectonics of the southeast anatolian orogenic belt
(Wiley, 2023) Yılmaz, Yücel; Yiğitbaş, Erdinç; Çemen, İbrahim
The tectonic development of the Southeast Anatolian Orogenic Belt (SAOB) is closely related to the demise of the NeoTethys Ocean that existed between the Arabian and Eurasian plates from the Late Cretaceous to Late Miocene. This ocean contained several continental slivers and intraoceanic magmatic arcs. The continental slivers represent narrow tectonic belts rifted off and drifted away from the Arabian Plate while the NeoTethyan Ocean and the backarc basins were opened. These slivers later collided with each another during which the branches of the oceans were eliminated and the continental slivers were integrated in the subduction zone and turned into metamorphic massifs. During the Late Cretaceous, the first collision occurred when an accretionary complex was thrust over the Arabian Plate's leading edge. Despite the collision, the ocean survived in the north and its northward subduction generated a new intraoceanic arc, which collided later with the northerly located continental slivers. During the Middle Eocene, the metamorphic massifs and the intraoceanic arc front migrated to the south. The new magmatic arc collided with the southerly transported nappe package during the Late Eocene. The amalgamated nappe pile eventually obducted onto the Arabian Plate during the Late Miocene. The collision produced escape structures during the Neotectonic period.
Quantifying the Rock Damage Intensity Controlled by Mineral Compositions: Insights from Fractal Analyses
(MDPI, 2023) Dinç Göğüş, Özge; Develi, Kayhan; Çalık, Ayten
Since each rock type represents different deformation characteristics, prediction of the damage beforehand is one of the most fundamental problems of industrial activities and rock engineering studies. Previous studies have predicted the stress–strain behaviors preceding rock failure; however, quantitative analyses of the progressive damage in different rocks under stress have not been accurately presented. This study aims to quantify pre-failure rock damage by investigating the stress-induced microscale cracking process in three different rock types, including diabase, ignimbrite, and marble, representing strong, medium-hard, and weak rock types, respectively. We demonstrate crack intensity at critical stress levels where cracking initiates (σci), propagates (σcd), and where failure occurs (σpeak) based on scanning electron microscope (SEM) images. Furthermore, the progression of rock damage was quantified for each rock type through the fractal analyses of crack patterns on these images. Our results show that the patterns in diabase have the highest fractal dimensions (DB) for all three stress levels. While marble produces the lowest DB value up to σci stress level, it presents greater DB values than those of ignimbrite, starting from the σcd level. This is because rock damage in ignimbrite is controlled by the groundmass, proceeding from such stress level. Rock texture controls the rock stiffness and, hence, the DB values of cracking. The mineral composition is effective on the rock strength, but the textural pattern of the minerals has a first-order control on the rock deformation behavior. Overall, our results provide a better understanding of progressive damage in different rock types, which is crucial in the design of engineering structures.
Treatment of Pb-contaminated soil by electrokinetics: Enhancements by varying voltage, chelant, and electrode material
(Elsevier B.V., 2023) Taneja, Sonam; Karaca, Öznur; Haritash, Anil Kumar
This work examines the removal of lead (Pb) from artificially contaminated soils (1000 mg/kg Pb) using the Electrokinetic Remediation (EKR) technique. Operating parameters, including periodic voltage gradient, electrolyte amendments with ethylenediaminetetraacetic acid (EDTA) and a non-ionic surfactant (Tween 80), and type of electrode material were investigated. Results indicated that a high voltage gradient (2.5 V/cm), in conjunction with EDTA as electrolyte, and stainless-steel electrodes favored the overall removal process. Pb removal by selected electrolytes was in order EDTA (65 %) > Distilled water (64.1 %) > Tween 80 (6.2 %). Visual Minteq v.3.1 software was employed to predict the chemical equilibrium of different chemical species of Pb against pH. Results confirmed that when EDTA was used as an electrolyte, the [Pb-EDTA]2− complex predominated over the Pb(OH)2 complex at an alkaline pH, resulting in more removal. Findings suggested that stainless steel was a better alternative to graphite with respect to removal efficiency and corrosion effect at the anode. Considering the maximum Pb removal with EDTA at higher voltage, the energy consumption was also maximum (78.3KWh/m3). Nevertheless, the economic evaluation suggested that the cost per gram removal of Pb was lowest in this experiment (8 US$/g Pb) and, thus, can be considered for practical applications to treat the Pb-contaminated soils.
Combined effects of high voltage gradient and electrolyte conditioning on electrokinetic remediation for chromium (VI)-contaminated soils
(Springer Science and Business Media Deutschland GmbH, 2023) Taneja, Sonam; Karaca, Öznur; Haritash, A. K.
Disposal of chromium-containing industrial waste has led to soil contamination at dispersed locations around the globe. Considering the carcinogenic, non-biodegradable, and bioaccumulating nature of hexavalent chromium Cr (VI), it is per-tinent to treat the contaminated soils. Electrokinetic Remediation (EKR) is a promising technology to remediate metal-contaminated soils under the influence of an electric field. This study investigated the removal of Cr (VI) by EKR, enhanced with a combination of high voltage (50 V), electrolyte conditioning using EDTA (0.1 M), and type of electrode material. Under controlled conditions using distilled water, low voltage (20 V at 1 V/cm) resulted in 22% removal, while high volt-age (50 V at 2.5 V/cm) resulted in 55% removal of Cr (VI) in 10 h of treatment period. The removal was further enhanced to 77% by amending with ethylenediaminetetraacetic acid (EDTA 0.1 M) as an electrolyte at a high voltage gradient of 2.5 V/cm. Classifying the role of electrode (graphite and stainless steel), based on the removal efficiency and corrosion of electrodes, graphite resulted in higher removal compared to stainless steel but with a significantly higher corrosion effect. Characterization of soil after EKR experiments exhibited improved liquid and plastic limits, and insignificant difference in Total Organic Carbon (TOC) and other parameters related to soil health. Energy consumption and cost-estimation revealed that application of high voltage, along with conditioning of electrolyte with EDTA can significantly increase removal of Cr (VI) in short period of time in a cost-effective (0.8 US$/g) way, thereby can be applied for rapid treatment of large volumes of soil without affecting the properties of soil.
Differential responses of hydrochemical factors and LULC changes on the spatial and temporal hydrogeochemistry of the eco-sensitive Baraila wetland, Bihar, India
(Springer Science and Business Media Deutschland GmbH, 2023) Aslam, Alvia; Ahmad, Tauseef; Ranjan, Rajesh Kumar
Freshwater scarcity, deterioration and associated water management remain to be one of the most challenging aspects of high-population density economies especially in subtropical/tropical regions. The present research deals with hydrogeochemical analysis of the eco-sensitive Baraila wetland and possible sources of anthropogenic pollution. The hydrochemical characterization was performed in GIS environment, considering meteorologically induced parameters and spatial variability. Temporal variations were assessed through different seasons, namely pre-monsoon, monsoon and post-monsoon with the help of multivariate statistics. The changes in water depth across the seasons showed significant hydrochemical variations in the vertical profile of the wetland apart from thermal demarcation. Seasonal variations in the hydrogeochemistry were induced by multiple physicochemical parameters, geochemical processes, geomorphology of the surrounding area and land use and land cover (LULC) changes. The pre-post flooding changes revealed that aquatic vegetation was increased by 15.36% whereas a major decrease in water bodies (− 73.2%) occurred. Dissolved oxygen (DO), pH, temperature and carbonates are fundamental towards establishing wetland’s water chemistry. The water type is primarily of Ca-HCO3 type, mostly derived from rock-water interactions and cation exchange processes. Irrigational quality of water was assessed through multiple indices (sodium adsorption ratio (SAR), %Na, residual sodium carbonate (RSC), magnesium hazard (MH) and total hardness (TH)) and plots. The heavy aquatic vegetation abundance and eutrophication because of agricultural run-off is currently the major issue with the Baraila wetland and may be playing a simultaneous role in regulating the water chemistry to a large extent apart from other geochemical processes. The hydrogeochemical interactions between sediment and overlying water have created distinct effects on biota and land use/land cover changes. Their role in the landscape is prominent in this respect and may be utilized for environmental management, eco-tourism and employment boost. Serious lack of hydrogeochemical studies in this important floodplain wetland and its rapid deterioration deems it necessary to focus on the comprehensive research and wetland management options for its conservation and sustainable usage in future.
The 20 july 2017 Bodrum-Kos Earthquake (Mw 6.6) in southwestern Anatolia, Turkey
(Universidad Nacional de Colombia, 2021) Över, Semir; Özden, Süha; Kalkan Ertan, Esra; Turhan, Fatih; Coşkun, Zeynep; Pınar, Ali
A 6.6 (Mw) earthquake struck the western part of Gökova Gulf in the eastern Aegean Sea on July 20, 2017. The fault plane solution for the mainshock shows an E-W striking normal fault with approximately N-S (N4°E) tensional axis (T-axis). Fault plane solutions for 33 aftershocks offer two groups of normal faulting with E-W and NE-SW to ENE-WSW orientations. The inversion of the focal mechanisms of the aftershocks yields two different extensional stress regimes. The stress regime obtained from 12 focal mechanisms of aftershocks and the mainshock is characterized by an approximately N-S (N5°E) σ3 axis, while the other regime calculated from 21 focal mechanisms of aftershocks exhibits σ3 axis in an NW-SE (N330°E) direction. The latter extension significantly affects the basin’s growth in the area where the earthquake occurred. Twenty-four focal mechanisms of earthquakes in and around Gökova Basin before the 2017 earthquake (1933-2017) were included in the inversion to determine the stress state effective in a larger area. The inversion yielded an extensional stress regime characterized by approximately N-S (N356°E) σ3 axis. E-W trending faults inferred in the central part of Gökova Fault Zone, bordering Gökova Gulf in the north, also indicate N-S extension. The NW-SE extension obtained from NE-SW aftershocks appears to be locally effective in the northwest of Gökova Gulf. N-S extension, which appears to act on a regional scale, may be attributed to geodynamic effects related to the roll-back of the African subduction beneath the Aegean.
Hydrogeochemical and isotopic monitoring of the Kestanbol geothermal field (Northwestern Turkey) and its relationship with seismic activity
(TUBİTAK, 2021) Şanliyüksel Yücel, Deniz; Özden, Süha; Marmara, Harika
Kestanbol geothermal field is located in northwestern Turkey and is one of the highest temperature geothermal fields in the Biga Peninsula. In this study, one geothermal well, two geothermal springs, and two cold springs were monitored for one year in Kestanbol geothermal field to determine hydrogeochemical and isotopic characteristics. Additionally, any possible relationship between seismic activity and variations in the hydrochemistry of geothermal water was investigated. The Kestanbol geothermal field is controlled mainly by the right-lateral strike-slip Kaplıca fault with normal components. The distribution of the geothermal waters is roughly parallel to the fault. The temperature, electrical conductivity, salinity, and pH value of the geothermal waters were within the range of 59.5 to 74.6 °C, 30300 to 35700 μS/cm, 19.6 to 23.3‰ and 6.13 to 6.83, respectively. The temperature interval was from 11.2 to 25.4 °C for cold waters. The hydrochemical facies of the geothermal waters were Na-Cl type, and the cold waters were Ca-HCO3-Cl type. The high concentrations of As, Ba, Fe, Li, and Mn in geothermal waters were mainly derived from prolonged water-rock interactions under high-temperature conditions. The δ18O and δ2H contents of cold waters indicated meteoric origin. The geothermal waters were enriched in δ18O and δ2H and located on the mixing line between local groundwater and fossil seawater, indicating mixing processes. During our study period, 20 earthquakes with Mw 3.5 and above were recorded in the close surroundings of the Kestanbol geothermal field, and temporal variations in the physicochemical and chemical compositions of geothermal waters were observed. Concentrations Cl- of the geothermal waters exhibited decrease after the Tartışık-Ayvacık earthquake (Mw = 5.0), indicating more supplement of groundwater with shallow origin under the increase of tectonic stress.

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