Jeoloji Mühendisliği Bölümü Makale Koleksiyonu

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https://hdl.handle.net/20.500.12418/621

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Evidence for surface rupture of the 1939 Erzincan earthquake based on field data and paleoseismology on the Ezinepazarı Fault (North Anatolian Fault Zone, Central Anatolia)
(Tübitak, 19.01.2023) Koçbulut, Fikret
The Ezinepazarı Fault (EPF) is an active segment that restricts the Niksar Basin in the central part of the North Anatolian Fault Zone and has been the source of the devastating Mw 8.0 earthquake in the last 100 years. Traces of the surface rupture of the EPF, which occurred in AD 1939, can still be observed in the field today as a right-lateral strike-slip character. While paleoseismological studies were mostly focused on the western part of the North Anatolian Fault Zone (NAFZ) in previous studies, the studies on the central and eastern parts of the NAFZ are rarely addressed. In this context, trench-based paleoseismology studies were carried out on the surface rupture traces in order to determine both historical/prehistoric earthquakes caused by the fault and the Quaternary period characteristics of the EPF. According to the data obtained, at least two historical earthquake activities have been detected besides the last 1939 earthquake on the EPF. Accordingly, the first and second events occurred in E1: 5871 ± 2300 BP and E2: 1651 ± 128 BP, respectively. When the determined data are compared with the historical earthquake catalogs, it is concluded that Event 2 (E2) can be correlated with the AD 343 Niksar earthquake; thus, the EPF has an irregular earthquake recurrence interval.
The 2023 Pazarcık (Kahramanmaras?, Türkiye) earthquake (Mw 7.7): implications for surface rupture dynamics along the East Anatolian Fault Zone
(The Geological Society, 27.04.2023) Koçbulut, Fikret
Southern Türkiye faced widespread catastrophic destruction by two devastating earthquakes on the same day. As the earthquakes occurred at 04:17 (Mw = 7.7, Pazarcık, Kahramanmaraş) and 12:30 (Mw = 7.6, Elbistan, Kahramanmaraş) on 6 February 2023, neighbouring active fault systems were broken in succession between the Hatay and Malatya provinces in the region. The first earthquake, one of the largest earthquakes in this region during the last century, caused major fatalities and widespread damage to infrastructure and buildings, and produced large-scale seismo-gravitational surface deformation such as landslides, lateral spreading, liquefaction and extensional cracks. Here, we present the surface rupture geometry and coseismic displacement characteristics of the fault systems, determined by field observations immediately after the 6 February 2023 Pazarcık (Kahramanmaraş, Türkiye) earthquake (Mw = 7.7). Preliminary results show that the total rupture length (Lmax) is 270 ± 10 km on the Karasu, Pazarcık and Erkenek segments of the East Anatolian Fault Zone. Left-lateral strike-slip faulting developed with a maximum horizontal displacement (Dmax) of 7.30 m and an average displacement (Davg) of 3.00 m. Although the surface rupture generally exhibits a narrow deformation zone width of 2–5 m, this expands to 50 m in some sections of the faults. The implications for rupture dynamics suggest that fracture development started on a secondary fault (Narlı Fault), transferred to the main fault and triggered the breaking of asperities on the Pazarcık segment, which exhibits a long period of accumulation of stress, to initiate the major rupturing.
More evidence of tropical conditions in the Middle Eocene Climatic Optimum (MECO) with new fossil woods from North-Central Türkiye
(Tübitak, 17.11.2023) Koçbulut, Fikret
Fossil wood descriptions are among the most important indicators in understanding forest structures across geological ages. This study was carried out to obtain new findings about the Middle Eocene Climate Optimum (MECO) period of Anatolia with new samples collected from the Middle Eocene-aged fossil area near Amasya-Göynücek. The fossil area falls into the Göynücek Volcanics in the region. Transverse, radial, and tangential microscopic sections were taken from three new fossil wood samples, and all identifications were performed on these microscopic sections. As a result, the fossil species were identified as Pinuxylon cf. P. tarnocziense, cf. Dichrostachyoxylon zirkelii, and Laurinoxylon perseamimatus based on their wood anatomical features. In all three fossil woods, the growth rings are quite wide and their boundaries are indistinct. This indicates the existence of warm tropical conditions in the MECO period. On the other hand, the extant representatives of the angiosperm genera identified here are found in tropical-subtropical forests. Overall, more information was obtained about the forest structure and climate of tropical conditions in the MECO period of Anatolia.
Wood and leaf remains of palms with affinities to Sabal Adans., from the middle Eocene of Turkey
(Tübitak, 16.01.2023) Koçbulut, Fikret
Two new fossil species based on the study of wood remains and leaf imprints from the middle Eocene Çekerek Formation (central-northern part of Turkey) are assigned to the palm family Arecaceae. Standard thin sections from the two samples of fossil wood were investigated and identified as Palmoxylon sabaloides Greguss 1969, with close xylotomical affinities to the modern genus Sabal Adans. The leaf imprints are weakly costapalmate and correspond to the genus Sabal as well. Based on the short petiole extension (costa), the leaves resemble the fossil-species Sabal lamanonis (Brongn.) Heer, 1855. This fossil-species was abundant in Paleogene strata of western and southwestern Europe but has only rarely been described from Cenozoic strata of the Eastern Mediterranean region. The presence of this species, in combination with previously reported pollen records of mangrove palms, indicate warm (sub)tropical conditions in the middle Eocene of north-central Turkey and may reflect the Middle Eocene Climate Optimum (MECO).
The Performance of Hyperspectral Measurements Integrated into Multispectral Data on the Detection of the Alpine Chromite Deposits in the Ophiolite Complexes
(Pleiades Publishing, Eylül 2023) Canbaz, Oktay
Intense tectonic activities and alterations in ophiolites of the Alpine-Himalayan Orogeny Belt complicate the delineation and mapping of chromite-bearing rocks by traditional geology surveys. This study tests the performance of ASTER-based remote sensing in a region covered by ophiolite rocks with complex geology, alteration, and intense tectonism in Eastern-Central Anatolia. Today, there are many chromite deposits and detected mineralizations in the study area. The fact that there was almost no chromite mining activity in the study area at the acquisition date of the ASTER data, highlights the usability of the results of the remote sensing methods and techniques applied in the study for mineral exploration activities. According to field surveys, petrographic examinations, and ore microscopy, the ophiolite rocks consist of serpentinized peridotite, harzburgite, dunite, diabase, and gabbro. Chromite mineralizations occur in dunites such as disseminated, banded, and lens-shaped. Hyperspectral signatures obtained from the representative rock and mineralization samples using ASD FieldSpec 4 Hi-Res have been integrated into the advanced spaceborne thermal emission and reflection radiometer (ASTER) multispectral satellite data. This study shows the performance of image enhancement techniques such as band ratio, minimum noise fraction (MNF), and spectral classification such as matched filtering (MF). The boundaries of ophiolite rocks with band ratio techniques are distinguished at the regional scale of the boundaries of sedimentary and igneous rocks, but sub-ophiolite rock units are not distinctly appearing within the ophiolite rocks. The MNF results can distinguish chromite-bearing rocks from the other rocks, although the boundaries of the rocks are not very distinct. The MF results map the sub-ophiolite units with high accuracy, except for the diabase dykes. The MF results have an overall accuracy of over 84% and a kappa coefficient of 0.74. Most of the chromite-bearing sites identified in the MF are currently being operated as chromite deposits. Consequently, this study shows that the MF spectral classification can be high performance in the delineation of chromite-bearing rocks in the ophiolite complexes.
Application of Spectral Analysis and Image Processing Methods to Discriminate Hydrothermal Alteration Minerals Around the Tutakdağı (Şebinkarahisar-Giresun) Lead–Zinc Deposits, Northeastern Turkey
(Springer, Ağustos 2023) Canbaz, Oktay
The Tutakdağı (Şebinkarahisar-Giresun) area is located in the southern part of the Eastern Pontides, northeastern Turkey. It contains numerous types of mineralization, examples include massive sulfide, porphyry, skarn, and vein. The Tutakdağı area contains vein-type Pb–Zn deposits hosted by Upper Cretaceous volcanic rocks. Hydrothermal alteration and oxidized weathering products are well exposed in this mineralization area. Due to the inaccessible points, steep slopes, and rugged topography of the area, it is difficult to apply traditional geological field studies. This research addresses the applicability of remote sensing methods to identify and map alteration mineralogy within the area and presents the results of a set of remote sensing investigations, including spectral measurements, band ratios, relative absorption band depth, principal component analysis, and matched filtering techniques on the Landsat-8 OLI and the ASTER data sets. The spectral investigations were performed on the representative altered rock samples and the powder samples obtained during the clay separation processes. The spectra of hydrothermal alteration minerals like kaolinite, halloysite, illite, montmorillonite, kaolin/smectite, illite + smectite, illite + montmorillonite, montmorillonite + smectite, muscovite, chlorite, and calcite and the iron oxide/hydroxide minerals like jarosite, limonite and goethite were identified. A mineral distribution map has been prepared, and all the outputs on these maps contain useful information to track the distributions of hydrothermal alteration minerals, weathering-related iron oxide/hydroxide occurrences surrounding mineralization zones, and the lineament/lineament density. These maps are prepared in a shorter time and with lower costs compared to classical field geological methods and can make a valuable contribution to the exploration of new lead–zinc deposits in the region.
DANIAN (SBZ2) LARGER FORAMINIFERA FROM THE BECIRMAN FORMATION (SOUTHEASTERN TURKEY) AS EVIDENCE OF ROTALIIDS DIVERSITY IN LOWER PALEOCENE SHALLOW-WATER ENVIRONMENTS
(Milano University Press, 2022) özgen erdem nazire
An important shallow marine deposit is described and illustrated with focus on the systematics and biostratigraphy of larger foraminifera from three stratigraphic sections of the Becirman Formation from the Batman and Siirt regions (Southeastern Turkey). A quite diverse association, mostly dominated by rotaliids (11 species belonging to 7 genera) and subordinate porcelaneous and agglutinated taxa, is documented as well. The fossil assemblage, including Elazigina dienii, Rotospirella conica, Praelockhartia cf. neoakbari, Cuvillierina cf. sireli associated with Mardinella daviesi and Idalina sinjarica, indicates the late Danian SBZ2. The abundance of rotaliids is linked, in this time frame, to the recovery of the shallow benthic communities after the K/Pg extinction including increase of surface water temperatures and oligotrophy. This was possibly due to the climatic warming recorded at the end of the Danian (Latest Danian Event), thus promoting a rapid adaptative radiation of rotaliids at genus rank.
First micropalaeontological record from the early and middle Eocene Mamuca Formation of the Dümrek Basin, western Central Anatolia, Turkey: Biostratigraphy, depositional history and palaeoclimate
(Elsevier, 2022) Özgen Erdem, Nazire
This study presents the stratigraphy, biostratigraphy and palaeoecology of a 420- m thick sequence of the Mamuca Formation (Dümrek Basin, Eskis¸ehir, Turkey). The age for the strata of the Mamuca Formation in the Çakıro˘glu Creek section is narrowed to late Ypresian-Lutetian (early-middle Eocene) by benthic foraminifera (Nummulites planulatus, N. burdigalensis, Assilina placentula, A. laxispira and A. cuvillieri), planktonic foraminifera (Acarinina bulbroki, Acarinina rohri and Acarinina topilensis) and ostracoda (Eopaijenborchella longicosta and Bairdia gliberti). The sedimentation started in coastal conditions and changed basinward into a shallow marine environment. The palynological assemblage is documented by frequency of palms Spinizonocolpites, Proxaperties and Longapertites, and unknown botanical affinity of Psilodiporites iszkaszentgyoergyi linking them to mangrove environments, along with pteridophytic spores indicating coastal sedimentation. Subsequently, a relative sealevel rise is obvious, leading to a sharp increase in the abundance of organic-walled dinocysts and a decrease in mangroves, almost died-off. The following faulting caused a tectonically triggered subsidence of the basin and led to an environment that deepened even more, provided that it was still shallow marine conditions that allowed the accumulation of coarse-grained sediments, devoid of fossil. Palynological data, stable isotopes (δ18O and δ13C) and quantitative palaeoclimate estimates point to a warm (probably tropical) and humid climate during the late Ypresian and Lutetian.
Davulalan A-type granitoid-associated Cu, Mo, Pb, Zn, and REEs mineralization, Central Anatolia, Turkey
(Elsevier, Aralık 2022) Canbaz, Oktay; Gökce, Ahmet
In recent years, due to the high-reserve metallic and/or non-metallic mines detected in A-type granitoids, this interest is growing in these granitoids. Davulalan syenitoid is one of the A-type granitoids which are intruded in the Central Anatolian Crystalline Complex (CACC) in Turkey. This research discusses the ore productivity and fertility of the Davulalan syenitoid based on field studies, petrographic examinations, and geochemical data. The syenitoid consist of alkaline composition syenite and quartz-syenite, and calcic composition nepheline-syenite rocks. Two type mineral occurrences as vein and veinlets (stockwork) bearing Cu (up to 60 ppm), Mo (up to 308 ppm), Pb (up to 3600 ppm), Zn (up to 745 ppm), and REEs (up to 880 ppm), which are located in the center of the syenitoid and the contact zones of the marbles. As microscopically, argillization, sericitization, chloritization, carbonization, and silicification in the samples where are between the veins. The veins and veinlets include mainly galena, chalcopyrite, pyrite, native gold, magnetite, maghemite, specular hematite and hematite as ore minerals, and calcite, fluorite and quartz as gangue minerals. The geochemical data of unaltered/altered samples show tending to the K-feldspar and argillic/sericite alterations. Due to its similar to the Ocean Island Basalt (OIB) composition, strongly evolved and fractionated, likely high oxygen fugacity, the syenitoid a productive and fertility in terms of Cu, Mo, Pb, Zn, and REEs.
Engineering–geological investigation of the river bottom near a dam’s stabilization threshold based on two different evaluation methodologies
(Springer, 2022) Yılmaz, Işık
The article concerns engineering and geological studies of the river bed near the threshold stabilizing the water flow of the Włocławek hydroelectric power plant in Poland. We paid attention to the differences in river erosion behind the dam, as one section of the study area was dominated by erosion of potholes and the other by sedimentation of river material. A protective threshold (partly concrete, partly gabion) was built to stabilize the water flow and optimize the hydrological regime near the dam. As a result of the erosion process (behind part of the hydroelectric power plant) and sedimentation (behind part of the weir), this threshold is constantly being destroyed. This threatens uncontrolled changes in water level, instability of water masses and, consequently, constitutes a threat to the stability of the hydrotechnical structure. The principal aim of the study is to propose a new methodology to perform a risk assessment and to indicate how to protect the threshold structure. Initially, geodetic and bathymetric measurements were performed of the river bed, potholes and the threshold. Then the results were analysed, the risks were estimated and two independent risk assessment procedures were proposed. One suggestion concerning the area of potholes was to backfill them to protect the threshold made of concrete slabs. In the second section, there is a sedimentation of the river material around the gabion threshold, which is damaged, especially during flooding. To protect this gabion threshold, a different approach has been taken of modelling the water flow based on digital bottom models (DBMs). An engineering–geological investigation of one river bottom benefited from two types of protection features (a concrete threshold and gabion threshold) using two different methodologies to evaluate hazard and design subsequent protection of the thresholds. The results of our study support the structure's managers in maintaining its safety.
Surface geophysical methods used to verify the karst geological structure in the built-up area: a case study of specific engineering-geological conditions
(2021) Yılmaz, Işık
This article presents a research study of complex limestone karst engineering-geological conditions in the municipality Valaská near Banská Bystrica in Slovakia. The aim of the study is to demonstrate the impossibility of spatial identification of cave spaces using surface geophysical methods due to the specific engineering-geological conditions of a thick surface layer of anthropogenic fill containing highly heterogeneous anthropogenic material. Its maximum thickness is 3 m. Another specificific condition of the study area is its location in the built-up area, due to which the applicability of geophysical methods was limited. The article contains methodological recommendations to be used in analogous geological conditions with karst structures topped with anthropogenic fill, which complicates the identification of cave spaces. The recommended solution herein is the identification of the cave system using underground mapping of the karst and its projection onto the surface for which surface geophysical methods have been combined.
Shallow mixing and column performances of lime, fly ash and gypsum on the stabilization of swelling soils
(Elsevier, 2021) Yılmaz, Işık
Swelling soils are problematic in terms of geotechnique and they necessitate mitigation actions in preliminary works. The most commonly used method to mitigate the damage caused by swelling soils is to stabilize soil with chemical additives by using different techniques such as column and shallow mixing techniques. It is important to evaluate different additives and different techniques together in order to determine the most suitable additive material and the most appropriate technique when stabilizing swelling soils. The aim of this study is to investigate the column and shallow mixing performances of various additives on the stabilization of swelling soils. Lime, fly ash and gypsum were chosen as additives for this purpose. The study was conducted in the laboratory by creating the model of the land at the laboratory scale. Two different laboratory models were designed for each additive, one for investigating their shallow mixing performances, and the other one for their column performances. A curing time of 4 months was considered for all of the models. At the end of the curing time, in order to determine the changes on the swelling behaviour of the soil, free swelling test was carried out on the specimens taken from the small scale model boxes. The results showed that the best improvement was achieved with lime for both techniques with reductions of 99,8% and 51,9% in the swelling percent of the soil when using the shallow mixing and column techniques, respectively. Gypsum, on the other hand, exhibited the lowest performance for both techniques by reducing the swelling percent of the soil by 65,42% and 25,3% with the shallow mixing and column techniques, respectively. Lastly, the shallow mixing technique showed 47,9%, 64,41% and 40,12% higher performances than the column technique for lime, fly ash and gypsum, respectively.
Paleoenvironment characteristics and hydrocarbon potential of the Lower Miocene bituminous shales in Sivas Basin (Central Anatolia, Turkey)
(SPRINGER HEIDELBERG, 2016) Erik, Nazan Yalcin
This study is based around Karayun which is in the Sivas Tertiary Basin, one of the important sedimentary basins in Turkey. The units observed in the study area and nearby are Oligocene Hafik, Lower Miocene Karayun and Lower-Middle Miocene Karacaoren Formations and Quaternary alluvium. This study focused on samples from the Karayun Formation due to the presence of alternations of bituminous shale levels in the formation. The studied bituminous shales are characterized by relatively high total organic carbon values up to 10.44 % and S2 values ranging from 0.01 to 89.02 HC/g rock, indicating fair to excellent source rock. Most of the bituminous shales are at the immature to early mature stage for hydrocarbon generation. Generally, genetic potential values are over 2 mg HC/g rock. The hydrogen index value of samples are between 9 and 887 mg HC/g total organic carbon (TOC) (on average 333.62 mg HC/g TOC). Oxygen index values vary between 17 and 557 mg CO2/g TOC (on average 135.35 mg CO2/g TOC). On the basis of Rock-Eval pyrolysis analysis, kerogens are type I/II and type II/III mixed. Dominant organic matter observed in this formation is algal amorphous organic matter. Thermal alteration index (TAI), Spore colour index (SCI), vitrinite reflectance values (R-o) and T-max evaluations indicate that maturity of the unit is between diagenesis and the early mature zone, and at the beginning of the hydrocarbon-producing stage. As a result of a series of analyses, it was found that the Karayun Formation has organic facies of B, BC and C and limited hydrocarbon generation potential in the basin.
Deformational behaviour of continental lithosphere deduced from block rotations across the North Anatolian fault zone in Turkey
(ELSEVIER SCIENCE BV, 1997) Piper, JDA; Tatar, O; Gursoy, H
Theoretical considerations of lithosphere deformation across transform plate boundaries predict an expression in terms of distributed deformation. The magnitude of rotation is expected to diminish away from the fault zone in a way which depends on the length of the fault, the amount of displacement, and the ductility of the Lithosphere. Palaeomagnetic studies across the North Anatolian transform fault zone, which separates the Eurasian Plate and Anatolian Block in northern Turkey, show that clockwise rotations predicted from the sense of dextral motion are indeed present and have attained finite rotations of up to 270 degrees during the similar to 5 Ma history of Neotectonic deformation. Such rotations are, however, confined to narrow (similar to 10 km wide) zones between system-bounding faults and appear to have resulted from rotation in ball-bearing fashion of equidimensional blocks a few kilometres in size. Outside of this zone only anticlockwise rotations are observed; these are unrelated to deformation across the fault zone and record regional anticlockwise rotation of Turkey which is complementing clockwise rotation of Greece and accompanying Neogene opening of the Aegean Sea. The observed behaviour of continental lithosphere satisfies no plausible value of power law behaviour. We therefore conclude that relative motion across this transform boundary occurs as a discrete zone of intense deformation within a brittle layer comprising the seismogenic upper crust. This is presumed to be detached from a continuum deformation response to shearing in the lower crust and mantle beneath. (C) 1997 Elsevier Science B.V.
Gypsum: An additive for stabilization of swelling clay soils
(ELSEVIER SCIENCE BV, 2009) Yilmaz, Isik; Civelekoglu, Berrin
Low rise buildings are particularly vulnerable to ground movements sourced from swelling and shrinking of the expansive clay soils. Geotechnical engineers have long recognized that swelling of expansive clays caused by moisture variation may result in considerable damage to the overlying structures, and engineers should take them into the consideration. The literature contains a vast number of stabilizing techniques such as lime, cement and fly-ash for treatment of expansive clay soils. However the use of gypsum as a stabilizing agent is currently not clear. This paper deals with the performance of the gypsum as an additive for treatment of the expansive clay soils by means of swell potential and strength. Optimum water content for the best compaction of the bentonite was first determined by standard compaction tests. Different quantities of gypsum such as 2.5%, 5%, 7.5%, and 10% by mass were added to bentonite and compacted in optimum water content obtained. Atterberg limits, free swell and unconfined compressive strength tests were performed on treated and untreated samples, after a curing period of 7 days. Obtained changes in the plasticity, swell percent and strength parameters of treated and untreated samples indicated that gypsum can be used as a stabilizing agent for expansive clay soils, effectively. (C) 2009 Elsevier B.V. All rights reserved.
Microfacies and Depositional Environment of the Ilerdian Carbonates in the North-Western Tosya (SE Kastamonu) Region, Northern Turkey
(SPRINGER INDIA, 2019) Ozgen-Erdem, Nazire; Koc-Tasgin, Calibe
Ilerdian (early Eocene) carbonates in the northwestern Tosya region, northern Turkey, are characterized by porcellaneous larger benthic foraminifera; Glomalveolina, Alveolina, Orbitolites, Opertorbitolites and Cyclopertorbitolites are common in the southeastern Kastamonu region, in facies deposited on a low-gradient carbonate ramp. The inner ramp comprises of Miliolid-soritid wackestone, Soritid wackestone, Alveolinid-soritid wackestone-packstone, Alveolinid wackestone, Alveolinid-Nummulitid wackestone-packstone, algal wackestone, and Coralline algal pack-grainstone microfacies. The middle ramp deposits are composed of Alveolinid-nummulitid wackestone-packstone and Nummulitid wackestone-packstone microfacies. Overall, the succession reflects a long term deepening trend.

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