Sürdürülebilir Kalkınma Amaçları

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• MakaleAçık Erişim2025/r/gumushane/10323
  Geochronological and isotopic data from the adakitic Dodurga Pluton (Central Pontides, N Turkiye): new insights for the geodynamic evolution of the northern Neotethys

  Çimen, Okay; Gücer, Mehmet Ali; Simonetti, Antonio; Karaoglan, Fatih

  The Dodurga Pluton is located within the Central Pontides (northern Turkiye), has a SW-NE elongation, and consists of granodiorite and dacite porphyry. Previous studies have suggested that this pluton is Triassic in age, and its whole-rock geochemical systematics is consistent with that from adakitic magmatic occurrences rather than the classic arc granitoid suite. This study reports for the first time in situ/whole-rock radiogenic isotopic (Sr, Nd, and Pb) and mica/amphibole Ar-Ar age data to evaluate better its petrogenetic/geodynamic evolution and the chemical nature of mantle source(s). Unlike previous data, combined new in situ zircon U-Pb yield Late Cretaceous crystallization ages of 84.2 +/- 0.9 Ma and 86.9 +/- 0.9 Ma, and the Ar-Ar age data along with apatite fission track measurements suggest magma cooling extending to 82.3 +/- 0.4 Ma and 85.4 +/- 0.4 Ma, respectively. The apatite fission track (AFT) dating results also reveal that this pluton was buried at a depth of 2.5-3 km following a fast-cooling period during the Late Cretaceous and cooled/exhumed over similar to 2 km during the Middle-Late Miocene (15-10 Ma) in a slow cooling phase. The overall data reported here suggest that the Dodurga Pluton represents melts derived from an enriched/metasomatized mantle source that interacted with lower crustal mafic rocks in an active continental margin as a result of northward subduction of the northern branch of the Neotethys Ocean.

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• MakaleAçık Erişim2024/r/gumushane/10339
  Eocene magmatism related to postcollisional extension in the Eastern Pontides (NE Turkiye): 40Ar-39Ar geochronology, geochemistry, and whole-rock Sr-Nd-Pb-Hf isotopes

  Aydinçakir, Emre; Yücel, Cem; Kaygusuz, Abdullah; Bilici, Ozgur; Yilmazer, Sinan; Ruffet, Gilles

  The mineral chemistry, whole-rock geochemistry, 40 Ar / 39 Ar dating and Sr-Nd-Pb-Hf isotopes of the Eocene Narman (Erzurum) Volcanic rocks in the southeast of the Eastern Pontides Orogenic Belt (EPOB, NE Turkiye) were investigated. The Narman Volcanites consist of basaltic dyke, basaltic lava, and basaltic volcanic breccia facies. Volcanites contain plagioclase (An34-80), 34-80 ), clinopyroxene (Wo38- 38- 47En41-50Fs5-18), En 41-50 Fs 5-18 ), and olivine (Fo 68-90 ) as phenocrystals with magnetite/titanomagnetite microphenocrysts. New 40 Ar- 39 Ar ages suggest that these volcanic rocks erupted between 44.5 +/- 0.1 and 43.4 +/- 0.1 Ma, within the Middle Eocene (Lutetian). Narman Volcanites have calcalkaline character, with medium-high K content. Volcanites are enriched in large ion lithophile elements (LILE) and light rare earth elements (LREE), while they are depleted in terms of high field strength elements (HFSE). Chondrite-normalized rare earth element distributions have concave shape with moderate enrichment (LaN/LuN= N /Lu N = 2.78-7.99), leading to consideration that the magmas forming the volcanics derived from similar sources. Isotopically, the rocks in the Narman Volcanites have low-medium initial 87 Sr/ 86 Sr values (0.70405-0.70485), initial 143 Nd/ 144 Nd values (0.512606-0.512848) and positive Nd i (+0.5 - +5.2). Depleted mantle Nd model ages were T DM1 = 0.29-0.62 Ga and T DM2 =0.43-0.83 Ga. (206Pb/204Pb)i, 206 Pb/ 204 Pb) i , (207Pb/204Pb)i, 207 Pb/ 204 Pb) i , and (208Pb/204Pb)i 208 Pb/ 204 Pb) i values vary in the ranges of 18.246-18.709, 15.578-15.616, and 38.225-38.791, respectively. The initial (176Hf/177Hf)i 176 Hf/ 177 Hf) i ratios for the volcanites are between 0.282770 and 0.283013, while the epsilon Hf values range from +7.6 to +9. All the evidence supports the conclusion that the parental magma for the rocks probably derived from an enriched lithospheric mantle, previously metasomatized by fluids derived from subducted slab during asthenospheric upwelling, due to fragmented asymmetric delamination in a postcollisional extensional tectonic environment.

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• MakaleAçık Erişim2023/r/gumushane/12769
  A study on the magnetite skarn mineralization (Gümüşhane, Türkiye): a magnetic survey

  Sipahi, Ferkan; Sadiklar, M. Burhan; Gücer, Mehmet Ali; Aydin, Ali; Kara, Rasim Taylan

  Iron (Fe)-skarn mineralizations (Çambaşı, Dereli, Eğrikar, Karadağ, Kopuz, Sekü, Donguldere, Arnastal, Özdil, Ögene, İkizdere, Ovit Dağı, Kartiba, etc.) in the eastern part of the Pontides (NE Türkiye) are accommodated in the Pontide paleomagmatic arc and the eastern part of the Pontides Metallogenic Belt containing numerous various deposits. Fe-skarn mineralization around the Arnastal Plateau (Gümüşhane-Türkiye) is fragmentary in this area, which is covered with plants (grasses, flowers, etc.). Thus, it was attempted to describe the subsurface structures and Fe mineralization using an interpretation of the available geological and existing magnetic data in this area. Granitoid and volcano-sedimentary series (Upper Cretaceous) outcrop in the study area. These volcanosedimentary series consist of limestone, sandy limestone, marl, andesite, quartz andesite, basalt, and their equivalent pyroclastics. They include a thin layer of the red limestone (Upper Cretaceous) and olistolith recrystallized limestones (Jurassic-Lower Cretaceous). Zigana granitoid, intruding into all of these rocks, is high-K calc-alkaline and metaluminous and is classified as quartz monzonite, monzogranite, granite, and syenogranite as a result of its modal composition. Contact pyrometasomatic mineralization occurs in between the limestone and granitoids in the Arnastal Plateau. In addition to petrographic and mineralogical studies, magnetic methods were applied to an area of approximately 10 km2 to find any covered Fe deposits. Magnetic susceptibility values measured on the outcropped rocks ranged from 1 to 34 (10–7 SI) for limestone, 78 to 3750 (10–7 SI) for basalt, and 105 to 3946 (10–7 SI) for granitoids. It is considered that these ranges express the alteration (physical or chemical) of the rocks, their homogeneity, and the lack or presence of Fe minerals. The magnetic survey was conducted along a study area measuring 12,075 m long with 25 and/or 50 m station spacing. Processing of the magnetic data revealed the presence of eight buried Fe ores that could represent either massive or disseminated mineralization between the Sarıtaş and Kurtdere plateaus. Magnetite ore bodies may be present from the surface to a depth of approximately 15–25 m inside the limestone. In addition to the identification of new magnetite ore mineralization or bodies, a new geological map was designed by determining probable formation boundaries with this magnetic survey.

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• MakaleAçık Erişim2023/r/gumushane/10668
  Internal deformation of continental blocks within converging plates: insights from the Ovacik Fault (Anatolia, Turkiye)

  Zabci, Cengiz; Sançar, Taylan; Tikhomirov, Dmitry; Ivy-ochs, Susan; Vockenhuber, Christof; Friedrich, Anke M.; Yazici, Muge; Akçar, Naki

  The active tectonics of Anatolia is mostly characterized by its westward motion with respect to Eurasia between the Hellenic subduction in the west and Arabia-Eurasia continental collision in the east. Although most of the deformation is suggested to be confined along Anatolias boundary elements, viz. the North and East Anatolian shear zones, recent studies indicate a higher magnitude of internal strain accumulation, especially along the parallel/subparallel strike-slip faults of its central province. We present the first morphochronology-based slip rate estimate for one of these strike-slip structures, the Ovacik Fault, by using cosmogenic 36Cl dating of offset fluvial deposits. At the Kcseler Site (39.3643 degrees N, 39.1688 degrees E), two faulted risers, bounding the alluvial fan with its subplanar surface (NF1/NF1') and the inset terrace tread (NF1/T2), are offset 19-24 and 15-22 m, respectively. The scattered surface ages and variability of 36Cl concentrations in depth profiles suggest strong evidence for inheritance in alluvial fan and terrace deposits; thus, we used modelled depth-profile ages for both surfaces. The modelled ages 8-10 ka for NF1 and 6-8 ka for T2 yield slip-rate estimates 2.4 +0.5/-0.4 mm/a and 2.8 +0.7/-0.7 mm/a, respectively, for the upper-tread reconstruction of the NF1/NF1'and the lower-tread reconstruction of the NF1/T2. Our results together with previous slip-rate estimates for other structures show a significant internal deformation for Anatolia, especially along its subparallel strike-slip faults. These secondary faults slice Anatolia into several pieces giving rise to the formation of the Malatya-Erzincan, Cappadocian, and Central Anatolian slices, where the geometry is strongly controlled by the distribution of the Tethyan accretionary complexes.

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• MakaleYayıncıda açık erişim2022/r/gumushane/14916
  Tectonic and structural characteristics of Erzurum and its surroundings (Eastern Turkey): a detailed comparison between different geophysical parameters

  Özer, Çağlar; Öztürk, Serkan; Pamuk, Eren

  The tectonic and structural properties of Erzurum and its surroundings have been investigated by evaluating the seismo-tectonic b-value, magnetic anomaly, edge detection analysis (total horizontal derivative (THDR) and tilt angle (TA)), Curie Point Depth (CPD), P-wave velocity (Vp), and Vp / Vs (S-wave velocity) ratio and by imaging the regional distributions of these parameters. For this purpose, all parameters have been combined to be able to reveal the new useful results on the study region and are presented for different locations and depths. The Vp values have been accompanied by high Vp / Vs ratios and shallow CPD values in the areas with geothermal regions such as Tekman, Söylemez, and the northern part of Karlıova. In the tectonically active regions such as Ilıca, Dumlu, Pasinler, Çat, Karlıova and Karaçoban, high reduction-to – the-pole (RTP) total magnetic anomaly was accompanied by low Vp values in harmony. Besides, the low Vp values between 0 and 10 km and high b-values can be related to the weakness zones and the areas in which earthquake hazards are high in the study area. The low Vp values in the 0 km horizontal slice are in accordance with the high RTP total magnetic anomaly values in the triangle area between Aşkale, Ilıca-Dumlu-Pasinler, Narman, and Karaçoban. Uniformly, high Vp and low RTP total magnetic anomaly inclusions overlap in Çat and Tekman. In some regions such as Dumlu, Narman, Horasan, Karaçoban and south of Karlıova, the tilt angle values are positive (positive values in the tilt angle map correspond to the center of the structure causing the magnetic anomaly) and the Vp values are low, but there is not a complete harmony between these parameters. These results show that variations on these parameters are related to each other, and these types of geophysical data are required for tectonic and structural features at different locations and depth levels.

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• MakaleAçık Erişim2021/r/gumushane/14872
  Anatomy of october 30, 2020, samos (Sisam) –kuşadası earthquake (mw 6.92) and its influence on aegean earthquake hazard

  Bulut, Fatih; Doğru, Aslı; Yaltirak, Cenk; Yalvaç, Sefa; Elge, Murat

  We investigated rupture geometry, size, and slip distribution of October 30, 2020, Samos (Sisam)–Kuşadası earthquake combining seismographs, GPS measurements, and SAR analysis. Right after the earthquake, we measured 13 additional campaign-based GPS sites to intensify the available GPS network consisting of 10 continuous stations. We combined all available seismographs to have the best possible accuracy for mainshock and aftershock hypocenter locations. We compiled all available seismic profiles and integrated them using high-resolution bathymetry to map seismically active faults. The mainshock hypocenter is located at 37.913 ± 0.009 N° and 26.768 ± 0.017 E° and a depth of 12.3 ± 1.7 km. Our fault plane solution shows that the mainshock has almost a pure normal-type mechanism. Based on accurate aftershock locations as well as InSAR results, the mainshock rupture is subsegmented with two north-dipping rupture planes. The rupture probably starts on a low angle plane generating 1.1 m average slip between the depths of 9–14 km. It merges to a steep plane at 9 km depth where it generates 1.2 m average slip extending towards the surface near the shoreline of Samos (Sisam) Island. Total size of the two rupture planes and their average slips determine that the magnitude of the mainshock is (Mw ) 6.92 ± 0.02. The mainshock has substantially increased Coulomb stress on several fault segments near the towns Kuşadası and Söke, which have the potentials to generate strong earthquakes. It also nonnegligibly increased Coulomb stress on several fault segments south of İzmir giving a warning for increased earthquake hazard in this highly inhabited area.

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• MakaleAçık Erişim2020/r/gumushane/14581
  Excess lifetime cancer risk due to natural radioactivity in Gümüşhane Province, NE Turkey

  Maden, Nafiz; Akaryali, Enver; Gücer, Mehmet Ali

  In this study, 162 in situ measurements of 238U, 232Th, and 40K radionuclide concentrations dataset taken by the gamma-ray spectrometer in Gümüşhane, Turkey are presented. The gamma ray measurements were performed by a 512-channel, three-window gamma-ray spectrometry equipment made by GF Instruments. We first observed the radionuclides of the 238U,232Th, and 40K values in Gümüşhane. We then calculated the hazard indices of gamma radiation such as annual effective dose equivalent (AEDE), internal and external hazard index (Hin, Hex), and excess lifetime cancer risk (ELCR) based on the radionuclide abundances of 238U, 232Th, and 40K for the first time. In Gümüşhane, the average activity concentrations of radionuclides 238U, 232Th, and 40K were measured as 58.7 ± 34.3 Bq kg-1, 62.7 ± 37.2 Bq kg-1, and 1026.8 ± 486.0 Bq kg-1, respectively. The average outdoor annual effective dose equivalent and ELCR values were 132.2 ± 63.2 mSv yr-1 and 0.40 ± 0.19 × 10-3, respectively. Numerical results indicate that the radiological parameters (AEDE and ELCR) obtained for Gümüşhane Province were greater than the world’s mean values.

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• MakaleAçık Erişim2020/r/gumushane/12927
  Nature of clays in late cretaceous dacitic rocks in the eastern sakarya zone (Ne turkey): A geochemical and isotopic approach

  Sipahi, Ferkan; Gücer, Mehmet Ali; Sadiklar, Münür Burhan

  Late Cretaceous felsic rocks are common in the eastern Pontides (NE Turkey). These rocks developed as an island arc from the Jurassic to the Miocene; they also host numerous volcanogenic massive sulfide deposits. The Late Cretaceous dacites that outcrop around Zigana Mountain (Gümüşhane, NE Turkey) were exposed to intensive hydrothermal alteration. Widespread hydrothermal alteration of Late Cretaceous dacite in Zigana Mountain has led to the formation of well-developed clay minerals. Their main alteration products are sericite, chlorite, and carbonates (ankerite and calcite). The clay minerals identified by X-ray diffraction and differential thermal analysis include illite, chlorite, small amounts of kaolinite, and smectite. The polytype of illite is 2M1. Illites formed as a result of hydrothermal alteration of feldspars; they are also Fe-and Mg-poor. Chlorite is characterized by decreasing Fe/(Fe+ Mg) ratio with increasing alteration grade and has a trioctahedral structure. Chlorite geothermometer calculations (100–300°C) reflect the activities of hydrothermal solutions. Chlorite forms in more alkaline conditions compared with illite, as its formation is associated with the presence of carbonates. Oxygen and hydrogen stable isotope values, K-Ar dating of illites, and textural and chemical evidence suggest that clays might have formed mainly by alteration of minerals in dacitic rocks with hydrothermal fluids of magmatic origin during the Campanian under acidic–weak alkaline conditions.

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• MakaleAçık Erişim2020/r/gumushane/12898
  Assessment of acid mine drainage formation using geochemical and static tests in mutki (Bitlis, se Turkey) mineralization area

  Gücer, Mehmet Ali; Alemdağ, Selçuk; Akaryali, Enver

  In this study, geochemical analyses, as well as short-term contact leaching and acid-base accounting tests, were carried out to determine the occurrence of acid mine drainage (AMD) by static tests in the ore stockpile areas at the Mutki Cu-Fe-Cr deposit (Bitlis, SE Turkey). According to the short-term contact leaching tests, the high enrichment in trace element concentrations in ore-bearing samples, especially in potentially toxic metals such as Cr, Cu, Mn, and Zn, were directly related to sulphide and oxide mineralizations. The pH (3.27–4.05) values of water samples, together with the classification of the intracontinental water resources, indicated that the water quality is the fourth class. Leaching tests, paste pH (3.42–4.46) and sulphide-sulphur (3.9–13.4 wt%) values also suggested that there was AMD production potential in the mineralization area. The AMD production potential was supported by the high mobility of several elements, such as Fe, Mg, Cr, As, Cu, S, and Zn. In ore samples, net neutralization potential (NNP) and net potential ratio (NPR) values were less than –20 kg CaCO3 /t and 1, respectively. The basalts forming the basement rock of the stockpile area were characterized by permeable to slightly permeable properties that potentially increase the contamination risk of the groundwater due to seepage in the stockpile area. In order to prevent seepage in the stock area, geomembrane (synthetic waterproofing covers) should be laid at the base to ensure impermeability. The improvements planned in the stock area were modeled by the finite element method and seepage discharges at a depth of 5 m were determined as 1.34 × 10–17m3/s. Thanks to these planned applications, surface and groundwater pollution can be efficiently prevented.

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• MakaleYayıncıda açık erişim2016/r/gumushane/11364
  Organic geochemistry and element distribution in coals formed in eocene lagoon facies from the Eastern Black Sea Region,NE Turkey

  Saydam Eker, Çiğdem; Akpinar, İbrahim; Sipahi, Ferkan

  The amount and type,the inorganic element content,and the maturity of organic materials of Eocene coals,shaly coals,and coaly shales exposed in the Gümüşhane and Bayburt districts of the Eastern Black Sea Region of Turkey were investigated. The depositional environments and hydrocarbon potentials were also interpreted. The total organic carbon concentrations in the studied samples ranged from 0.50% to 63.08%. The samples from Özyurt,Kayadibi,and Tarhanas contained types II and III kerogen,and those from Sökmen and Manas contained type III kerogen. The samples contained Co,Cs,Ga,Hf,Th,U,Y,Mo,Be,Cd,Sb,and La,with average values similar to those of standard brown coals. The samples showed average contents of Co,Ga,Nb,Rb,V,Y,Cu,Pb,Zn,As,Be,and Se,similar to those of other Turkish coals. The sediment source of Eocene samples in the five areas was characterized by rocks with intermediate or mafic geochemical characteristics. The terrigenous/aquatic ratio of coal and shaly coal samples of the areas in question is >1. The sterane distribution was C29 > C28 > C27 and C29 > C27 > C28 for the Özyurt and Tarhanas areas,respectively. The average Tmax values for samples are between 424 °C and 460 °C. For samples Oz-1 and Ta-2,22S/(22S + 22R) homohopane (C32) ratios are 0.48 and 0.61,respectively; 20S/(20S + 20R) sterane (C29) ratios are 0.18 and 0.53,respectively; and Ts/(Ts + Tm) ratios are 0.015 and 0.64,respectively. The Pr/Ph ratios of the samples are >3. The studied samples have low sterane/hopane and high (C19+C20)/C23) ratios without anoxic biomarkers (17α(H)-28,30-bisnorhopane). Based on these data,the coals,shaly coals,and coaly shales were probably deposited under an oxic-suboxic mixture of marine and terrestrial environment conditions; these materials contain terrestrial organic matter and cannot generate hydrocarbon.

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