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Herein, Anatolian aurorae are reviewed based on the existing catalogs to establish a relationship between the aurora observations and past solar activity during the Medieval period. For this purpose, historical aurora catalogs for Constantinople and Anatolia are compiled based on the existing catalogs and compared with those in the Middle East region. The available catalogs in the literature are mostly related to the records observed in Europe, Japan, China, Russia, and the Middle East. There is no study dealing only with the historical aurora observations recorded in Anatolia and Constantinople. The data of the catalog show that there is a considerable relationship between the aurora activity and past strong solar activity. High auroral activity around the extreme solar particle storm in 774/775 and the Medieval grand maximum in the 1100s in Anatolia and the Middle East is quite consistent with the past solar variability reported in other scientific literature. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this study, in situ radioelemental ( 238 U, 232 Th and 40 K) measurements and heat production rate evaluation have been conducted at 132 sites in the Gümüşhane Pluton of the Eastern Pontides Orogenic Belt (EPOG) of Northern Türkiye. The average K, U and Th values for granites are 4.35 ± 0.71%, 5.85 ± 2.74 ppm, 22.13 ± 5.55 ppm, respectively; microgranites 4.33 ± 1.37%, 7.12 ± 2.23 ppm, 24.11 ± 9.59 ppm; metagranite 3.93 ± 0.68%, 6.24 ± 2.75 ppm, 12.87 ± 3.92 ppm; andesite/basalt 1.75 ± 0.74%, 3.22 ± 1.07 ppm, 9.01 ± 5.14 ppm. Based on the abundances of K, U and Th, the radiogenic heat production (RHP) values, which is a reflection of the geological rock types, are estimated as 3.52 ± 1.03 μWm − 3 , 3.86 ± 1.31 μWm − 3 , 2.93 ± 0.89 μWm − 3 , and 1.68 ± 0.63 μWm − 3 for granites, microgranites, metagranites and andesite/basalt, respectively. The average heat production value for the study area is estimated as 2.83 ± 1.39 μWm − 3 , which is closer to the upper continental crustal value; contrary to the highest heat production value of granitic basement and the lowest heat production values of the sedimentary rocks. The study region is depicted with very high level of Th/U value ranging from 0.11 to 23.19 with mean value of 3.53 ± 2.5, which is comparatively close to the upper continental crustal estimate of 3.8. The numerical results verify that mantle-derived magmas are subjected to contamination with both middle and lower crustal material constituted by fragments of southerly dipping subduction of Tethys Ocean during the late Mesozoic–Cenozoic. [ABSTRACT FROM AUTHOR]

The Pontides can be divided tectonically into three main sectors: Eastern, Central, and Western Pontides. Each of these represents an amalgamated tectonic mosaic consisting of remnants of oceanic, continental, and island arc segments. The Eastern and the Western Pontides meet in the Central Pontides, where they are structurally mixed and form a tectonic knot. The Central Pontides of northern Turkey is one of the best exposed segments of the southern margin of Eurasia adjacent to the Tethys Ocean. The study area also extends to parts of the Sakarya and Kirsehir continents. Magnetic spectral analysis, which has been used to estimate the Curie point depths and heat flow values, is employed to identify the thermal regime of the Central Pontides. The magnetic data of the region are separated into five subregions and the power spectra of each region is achieved by using 2D Fourier transform method to attain the average curie depth. The curie depth values changes across the studied region from 14.8 km in the south to 21.8 km in the north. The obtained results imply a high thermal gradient (39.2 °Ckm-1) and corresponding heat flow values (94.1 mWm-2) in the south of the research area. The northern part of the study area displays a low thermal gradient (26.6 ° Ckm-1) and low heat flow value (63.9 mWm-2), corresponding to the Central Pontides consisting of accreted oceanic crustal material. The determined values show the heat flow decrease within the accretionary prism toward the island arc-like Pontides. [ABSTRACT FROM AUTHOR]

The Eastern Pontide orogenic belt is divided into three subzones (northern, southern and axial zones) based on present lithologies and facies associations. NE-SW-, NW-SE- and E-W-trending fault systems, which play an important role in palaeotectonics and neotectonics of the Eastern Pontides, separate these zones. Three different methods were used to estimate the Moho depth from observed gravity value, namely (i) empirical relationship between Moho depth and Bouguer anomaly: (ii) spectral analysis of the radial wave number and; (iii) by the gravity inversion method. Power spectrum, a statistical approach, is a widely used technique to determine the depth of geological sources successfully. The empirical linear relations between the Bouguer anomalies and seismically determined crustal thicknesses have been used to compute depths to the Conrad and Moho discontinuities, which are consistent with the average depths obtained from the power spectrum method. The crustal structure was also determined from the inversion of a Bouguer anomaly profile along longitude 39°. Gravity inversion results are consistent with those obtained from the empirical relations and power spectrum methods. We calculated the maximum crustal thickness of 43.8 km in the studied region by using the gravity inversion method, which also showed that crustal thickness increases from north to south. [ABSTRACT FROM AUTHOR]

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We have carried out 48 in situ measurements on radioactivities of 238U, 232Th and 40K isotopes at the Gümüşhane granitoid plutons employing gamma-ray spectrometer with a NaI(Tl) scintillation detector. The radionuclide activity concentrations of 40K, 238U and 232Th ranged from 62.6 to 1680.8 Bq kg−1, 2.5 to 119.9 Bq kg−1 and 3.3 to 92.4 Bq kg−1, respectively. The mean concentration of natural radionuclides (40K, 238U and 232Th) was found to be 638.5 ± 421.6 Bq kg−1, 40.8 ± 27.4 Bq kg−1 and 33.5 ± 25.5 Bq kg−1, respectively. The mean values of the radium equivalent and the external hazard index were 137.9 ± 80.6 Bq kg−1 and 0.37 ± 0.22, respectively. The value of annual effective dose equivalent value (81.8 μSv year−1) is lower on average than in the world average of 460 μSv year−1. The external hazard index acquired in this study did not exceed the international safety standard levels, which means that Gümüşhane pluton does not produce any radiation hazards to the dwellers. [ABSTRACT FROM AUTHOR]