Türkiye Jeoloji Bülteni

Abstract: This study investigated the morphometric and morphogenetic characteristics of dolines in the Bozdağ Massif, located in the north of Karaburun Peninsula. Dissolution dolines are one of the characteristic surface features of mid-latitude high karst plateaus, and doline morphometry is one of the methods commonly used to study the morphotectonic evolution characteristics of karst plateaus. In this study, an automatic extraction technique wasused with a high-resolution digital elevation model to determine the areal distribution, density and morphometric characteristics of dolines. After the dolines were identified, several morphometric parameters such as area, perimeter,circularity index, length, width and elongation rates were calculated. According to the analyses and results obtained, a total of 564 dolines were detected in the area, with a maximum density of 74 dolines/km2. All the dolines, with anaverage elevation of 1,080 metres, are located on limestone from the Camiboğazı Formation. The dolines extendin roughly NW-SE direction, parallel to lineaments in the area, which formed in relation to tectonic processes that started with palaeotectonic evolution and influenced the Karaburun platform in the Izmir-Ankara zone during the Cretaceous period

Abstract: The terrestrial Neogene sequence of the Menteş Peninsula, located in the Urla section of the Foça Depression, comprises the Middle Miocene Urla Group. The Urla Group unconformably overlies the late Early Miocene Kocadağ Volcanics and consists of sedimentary and volcanic rock units. A sedimentary succession, consisting predominantly of lacustrine deposits, begins with the Bozavlu Formation reflecting alluvial fan sedimentation, continues with the volcano-sedimentary Güvendik Formation deposited on the lacustrine shoreface, and ends with the Urla Limestone. The Güvendik succession frequently contains volcanoclastic density currentlevels in epiclastic (lahar and turbiditic sandstone) and pyroclastic (ignimbrite, base surge, blocky ash flow) facies,reflecting the early period of Menteş volcanism. The Urla Limestone conformably overlies the Güvendik Formation.The Urla Limestone succession contains tuff interlayers with ash fall facies of the Menteş volcanism from bottom totop. Algal bioclastites and oncoidal limestones were deposited at the base and transgressive parts of the limestone succession, formed by waves in the foreshore belt. The Middle Miocene alkali volcanism of the Menteş Peninsula is represented by the Menteş Volcanics and the Ovacık Basalt. Menteş volcanism, which yields products in the trachyte rhyolite composition range, consists of pyroclastics, composite lava domes and dome-flows. The pyroclastic sequence starts with unwelded ignimbrites containing accidental lithics derived from the Ovacık Basalt, and continues with  successive levels of blocky ash flow and base surge. Menteş volcanism evolved in the lake where the Güvendik and Urla Limestone units were deposited. Basic volcanism, which developed laterally to the Menteş acidic volcanism, continued to be active intermittently from the beginning of Urla Limestone deposition to the last stages. 

Abstract: The sedimentary rock groups in Türkiye, which comprise valuable geological heritage, have been the focus of important publications world wide, first in palaeontology and then in sedimentology. The distribution of sedimentological units on the geological map of Türkiye is very diverse and corresponds to the palaeotectonic history of the region. The rocks suitable for karstification, mainly carbonate rock groups, have a significant volume in Türkiye. This volume, together with the effects of the climate zone and tectonics, has led to the formation of karstic caves and sink holes on a large scale. These karstic structures have created natural resources that attract tourists.Today, geotourism is a concept that combines both geological and touristic assets. The total number of visitors inthe 4-year period between 2020 and 2023 was 355,923 in Karaca Cave and 514,947 in Çal Cave. As examples of geological resource assets in regions with limited economic development, attempts to evaluate Karaca and Çalcaves in terms of tourism can be measured as the important contribution of karst structures to tourism potentialin the Eastern Black Sea region. This study showed that rocks of sedimentary origin have a regional, global, and sustainable impact in the context of geotourism and play a role both in geological terms and as tourist attractions.

Abstract: This study aims to reveal the geomorphological characteristics of two natural bridges, which are among the rare landforms on the Murat River, and the factors affecting their formation, as well as the main problems relatedto these bridges, the work to be done for protection of the bridges, and their importance as geoheritage. The natural bridges, formed as a result of very special geomorphological processes, are located on the Murat River between the villages of Dibekli-Mollakara-Tazekent-Davut-Göğebakan-Taşbasmak in the south of Diyadin (Ağrı) District, in thearea we can call the Diyadin Geothermal Area (DGA). Observations were made in the field; Geological, geomorphological and tectonic features were examined, the elevations, lengths and widths of travertine ridges, cones and chimneys in the area were measured by a laser meter inorder to reveal the characteristics of travertine accumulation patterns and their coordinates were taken with GPS. Aliterature study was carried out and a geomorphology map was produced with ArcGIS 10.8 package software basedon the digital data obtained in the field studies.Köprüçermik Bridge on the Murat River is 64 m long in a NNW-SSE direction. The width of the bridge varies between 9.5-21 m in the upper section. The Murat River flows in a bed with a width of 7 m under the bridge. The thickness of the travertines forming the bridge is 15 m at the entrance and 22 m at the exit. Travertine depositioncontinues on the eastern slope of the entrance of the bridge.To the north of Köprüçermik Bridge there is a natural bridge called "Kudret Bridge" by the local people. The bridge, which is used as a highway bridge connecting the settlements east and west of the Murat River, is 30 meterswide and 63 meters long. The bridge opens near the NNW end of the travertine ridge extending in a NNW-SSEdirection. Among these natural travertine bridges, Köprüçermik Bridge has features rarely seen in the world. It was formed by the travertine ridges running in different directions because of the thermal waters coming to the surface along the tectonic lines on both sides of the Murat River; first gaining elevation in a vertical direction, and then by the mutual horizontal development of these ridges on the river bed. Kudret Bridge was opened by the Murat River undercutting the travertine ridge and then widening it. Kudret Bridge is a fossilised travertine bridge and has partially lost its primitive morphology. As with otherforms of travertine accumulation in the area (cones, terraces, chimneys, ridges, etc.), travertine bridges also facevarious natural and anthropogenic threats. These accumulated forms in the Diyadin Geothermal Area (DGA) should be protected as a karst geoheritage and the area should be declared as a geopark area.

Abstract: Although more than 4.000 minerals discovered in the world to date, some of them are very valuable interms of collection because they are very rare in nature. One of the rarest and most valuable minerals in the world ispainite [CaZrB(Al9O18)]. After its discovery in Myanmar (Burma) in southeast Asia in the 1950s, research has beenconstantly carried out on the possibility of this rare collectible and jewelry stone being found in other countries dueto its very high value. The main purpose of this study is to reveal the mineralogical and gemological properties of themineral painite can be searched for and found in Türkiye. It is known that painites are geologically formed and foundin skarn belts at the contacts of leucogranite of magmatic origin and marbles of metamorphic origin. As a result, ifpainite is to be sought in Türkiye and evaluated as a gemstone; the percentage amounts of the elements Ca, Zr and Bmust be taken in consideration as well as corundum, spinel, etc. in the geochemical composition of this mineral. It should be searched in geological environments of minerals; in particular, metamorphism contacts (skarn belts) and/  their alluviums should be investigated at the contact between igneous rocks and carbonate rocks.

Abstract: The Karakaya Complex consists of four different tectonostratigraphic units of similar age and reflects different tectonic and basin conditions. These units are Nilüfer, Hodul, Orhanlar Greywacke and Çal. unit. The Nilüfer unit consists mostly of metabasite and metasandstone with a small amount of quartz calcschists and marble overlying them. The Hodul unit, the most common unit in the Karakaya Complex, consists of light grey-white feldspar sandstone and dark grey-black shale siltstones. It is possibly a member of the Kaşal Limestone deposited ina narrow, intermittent area on a muddy sea floor in the form of lens-like ground reef dunes / benches. The Orhanlar Greywacke is composed of limestone and lesser spilite blocks, monotonous grey wacke and shale matrix within the Karakaya Complex. The Çal unit consists of pelagic limestone and burgundy-brown coloured radiolarites, mudstone levels and wide spread limestone olistoliths. In this study, the biostratigraphy of a Kaşal Limestone Member of the Hodul Unit of Karakaya Complex has been examined in SW İvrindi (Balıkesir). The geology of Kaşağıl Village, which is located 15 km SW of İvrindi, is characterized by a clastic matrix and Permian-Upper Triassic limestone blocks. Permo-Triassic foraminifers were obtained from the samples collected from the studied area and macrofossils were obtained such as ammonite, brachiopod fragments, crinoid, echinoid and gastropod fragments. Involutina ? jurassica JONES form was obtained from the strata forming the youngest levels in the measured stratigraphic sections.