Türkiye Jeoloji Bülteni

Abstract: The Yunak Fault Zone is located in the northeast part of the Afyon Akşehir Graben (AAG), which is a seismically active graben in Western Anatolia. During field-based studies, four segments within the Yunak FaultZone were mapped for the first time at a scale of 1/25,000, and named as the Cebrail, Üçkuyu, İncirli, and Ayrıtepe Segments. Their geometric, kinematic, and active tectonic features were analyzed for the first time. The finding sobtained from field studies indicate the presence of faults with lengths ranging from 3 km to 18 km and width sranging from 300 m to 3 km, with orientations varying between NNE-SSW, NE-SW, and E-W, capable of producing earthquakes with magnitudes ranging from 5.6 to 6.7. Paleostress analyses of fault slip data reveal that the NESW trending faults in the region were formed by pure strike-slip faulting under the influence of a N-S directed tensional and E-W directed compressional stress regime during the Miocene-early Pliocene. However, during PlioQuaternary extensional tectonics in western Anatolia, they were reactivated as dip/oblique-slip normal faults within multi-directional extensional tectonics in E-W, NE-SW, and NNE-SSW directions in the north eastern part of theAAG. In this study, the newly identified Akşehir Sub-Graben is controlled by the NE-SW trending dip-slip Yunak and Mevlütlü Fault Zones and exhibits characteristics of a cross-graben on the hanging wall block of the Sultandağı master fault.

Abstract: The Eastern Black Sea region (NE Türkiye) has important geological, historical, and natural value. The geological setting of the region includes the Paleozoic, Mesozoic, and Cenozoic periods. From a palaeobiological point of view, there have been five major extinction events since the formation of the Earth. Studies of the Cretaceous/Paleogene transition/extinction 66 million years ago (mainly platinum group element anomalies, Mg/Ca ratios, Srisotopes, C-O stable isotopes, and biostratigraphy) have identified the K/Pg boundary/transition markers in detail. In particular, the Eastern Black Sea region has a large Mesozoic-Cenozoic stratigraphic mass. Sedimentary rocks, which are fewer than the igneous and volcanic rocks, also outcrop in the region. These sedimentary rocks, therefore,provide insights in to the biostratigraphy of the region. K/Pg-aged neritic and pelagic sequences are distributed along the Black Sea on an east-west axis. The K/Pg transition in the sequences is indicated to be neritic-neritic at Ordu,pelagic-pelagic and neritic-neritic at Trabzon, and pelagic-pelagic and neritic-neritic at Artvin. These transitions were identified from foraminiferal biostratigraphy according to benthic Orbitoides-Lepidorbitoides and plankticG. gansseri-A. mayaroensis in the Late Cretaceous and benthic Shallow Benthic Zone (SBZ) 1-3 and planktic P0-P5 biozones in the Paleogene. Especially in the K/Pg transition/boundary in neritic sediments in the Ordu region; Orduina erki gen. n. sp. (Sirel, 1969), Laffitteina erki (Sirel, 1994), Orduella sphaerica n. gen. n. sp. (Sirel, 1999),Selimina spinalis n. gen. n. sp. (İnan, 1996), Sirelina orduensis n. gen. n. sp. (Meriç and İnan, 1998), and Cocoarotaorali n. sp. (İnan, 2003) were identified as new genus and species. In this distribution, K/Pg outcrop sections occur inOrdu, Trabzon, and Artvin. Based on the biostratigraphic data, it was determined that the successions in these three regions, which contain the transition between the Cretaceous and the Paleogene, are important palaeobiological geosites for both Türkiye and the world.

Abstract: Mineralogical (microscopy, microprobe, SEM, XRD, DTA-TG) and geochemical studies of Paleogene(Eocene?) volcanic rocks in the Polatlı region, exposed as domes and dykes, revealed the formation mechanism ofanalcime minerals within these rocks. The analcimes in these basic rocks were observed with clinopyroxenes and feldspars. The lack of aqueous minerals, aside from analcime, and the detection of residual leucite though XRD,DTA-TG, microprobe analyses, and microscopy, suggest that analcime formed through an ion-exchange process from leucite during post-magmatic evolution. SEM images further support this hypothesis, revealing rough, irregular,cracked, and microporous surfaces of analcime, which are characteristic of this ion-exchange transformation. Additionally, geochemical analyses show that the volcanic rocks were ultrapotassic at the time of their formation,with high K2O content not saturated with silica; thus, providing conditions conducive to leucite crystallization. These results suggest that volcanic activity related to continental rifting and tectonic stress during the collision and postcollisional period after the closure of the northern branch of Neotethys produced the volcanic rocks in the Polatlı region. The ultrapotassic characteristics of the Polatlı volcanic rocks, which are confined to a relatively limited area,suggest that they formed from a heterogeneous potassium-enriched mantle source. This source underwent partial melting, incorporating high-K continental components added to the mantle during subduction; thus, enabling the formation of leucite and subsequently analcime in the later stages of magmatic evolution. In this study, the analcime observed in these volcanic rocks subsequently formed from leucite through ion exchange during post-magmatic processes.  

Abstract: In this study, the aim was to reveal the palaeoecological and palaeoclimatic characteristics of the sediments around the Beysehir Lake basin, along with the gastropod fauna. As a result of the examination of samples taken from sediments from the Ancient Beyşehir Lake, 13 genera and 15 species belonging to the Gastropoda class of the Mollusk branch were identified. When the fauna was evaluated in terms of numerical abundance, the typical dominant species were Valvata pulchella living in rivers and Bithynia leachii living in shallow freshwater. It is thought thatthe lake was a freshwater environment fed by rivers during the time period when levels where Bithynia leachii and Valvata pulchella species were deposited together. In the time interval when Valvata pulchella and Bithynia leachiispecies decreased and species living in marsh and stagnant water environments such as Planorbis planorbis, Anisusvortex, and Gyraulus parvus increased numerically, the environmental conditions indicate temperate, very shallow, closed lake conditions. Valvata beysehirensis, which is an endemic species in the Ancient Beysehir Lake indicatinga freshwater environment fed by rivers, was observed at many levels of the basin. The presence of V. beysehirensisspecies, which was dated to the late Pleistocene in the literature, during the Pleistocene was revealed in this study.When the ESR dating results, ages determined by other researchers and palaeoecological characteristics of theidentified fauna are evaluated together, 7 arid and 6 wet climatic periods were effective in the study area during thePleistocene. The climatic conditions in the study area are compatible with the palaeoclimatic changes between MIS16-MIS 2 phases, which show global sea level changes in the last 659 thousand years.  

Abstract: The aim of this study is to compare the gemstone products (gemstones and gemstone jewelry) used by the Carian Civilization, which continued its reign from 1100 BC to 545 BC, with the gemstones obtained from the Carianregion and to investigate the archaeological and comprehensive reason for the use of jewelry. In order to investigate which present-day gemstone types in the Carian region were used in ancient times, the gemstones on various piecesof jewelry in the Milas Archaeology Museum and the Bodrum Underwater Archaeology Museum, where  artifact sexcavated from the Carian region are preserved, were examined for the first time not only from an artistic perspective but also from archaeological and scientific perspectives, and they were systematically inventoried. Among the gemstones found in the Bodrum Underwater Archaeology Museum and the Milas Archaeology Museum, which arethought to have been obtained from the Muğla region, only ancient products made of smoky quartz were found. Inaddition, sardonyx, likely brought from the Lydian region via trade routes, as well as gemstones thought to have originated from the Indian and Yemeni regions, and glass and ceramic materials used as gemstones were also identified.

Abstract: In the article by Karaoğlu (2024), the caption for both Figures 1 and 2 was presented incorrectly. Below, the corrected captions for both Figures 1 and 2 are provided in both Turkish and English, alongside the revised figure for clarity.