Türkiye Jeoloji Bülteni

Abstract: The obliteration of the Neo-Tethyan Ocean along the northern part of Turkey leads the development ofthe İzmir-Ankara-Erzincan suture zone (IAESZ). After the suturing stage; extension and magmatism concomitantlydeveloped on the both sides and along the IAESZ during the middle Eocene. During this stage, the areas confiningto Almus, Yıldızeli, and Yıldızdağ regions have experienced a severe magmatic activity. Middle Eocene magmatismin Almus and Yıldızeli areas are represented by the volcano-sedimentary successions. Besides, in Yıldızdağregion, gabbroic and dioritic intrusives are the dominant manifestations of magmatism. The volcano-sedimentarysuccessions from Almus and Yıldızeli areas represented by shallow marine sedimentary units at the lower parts andlava flows and volcanoclastic units at the middle to upper parts. Eight volcano-sedimentary sections from Almus andYıldızeli measured to demonstrate the evolution of the magmatic units developed coevally along the both sides of thesuture zone. In both regions; three different volcanic episodes are differentiated based on stratigraphy. First episodeincludes amphibole-basaltic andesite, andesite, and dacite. Second episode contains basalt and pyroxene-basalticandesite lavas and third episode represented by trachyte and trachyandesite dikes and stocks. The field data from theall regions demonstrated that middle Eocene magmatic units along the post-collision zone concominantly developedin a wide area and triggering of the magmatism controlled by the region-scale delamination and/or lithosphericremoval processes. 

Abstract: In this study, enhanced local wave number (ELWN) technique is presented to compute some modelparameters of isolated and magnetized geological structures such as horizontal position (exact origin), depth andsource geometry using the total field magnetic anomalies (TMAs). The technique uses analytical signal amplitude(ASA) and first- and second-degree horizontal and vertical derivatives of observed TMAs, and then simply computesthe model parameters without requiring a priori knowledge about the nature of the causative magnetized body.Additionally, inclination and declination angles of both magnetization and ambient field have no effects on theresults. In the ELWN technique source geometry, viz., structural index (contact/fault, dyke, horizontal cylinder andsphere) is determined using the depth and exact origin computed previously. Hypothetic simulations performed usingTMAs due to some simple shaped geological models have showed the ability of the technique. Moreover, an actualmagnetic data taken over the Kesikköprü iron deposit (Central Turkey), one of the largest iron reserve in Turkey,has been also analysed. A depth of 21.39 m has been computed for the magnetized geological source which includesthe mafic rocks rich in magnetic properties, and the iron ore body. The structural indices obtained have indicated adike-like or an intermediate form between a dike and a horizontal cylinder body for the magnetized source. Thesefindings are compatible with those of a recently published study. Hence, the use of ELWN technique is proposed forrapid and reliable model parameter estimations from TMAs as an alternative or supportive experiment to the inversemodelling studies.

Abstract: It is summarized what needs to be done and to be able to utilise three structurally different geologicalformations within the Çanakkale province as geo-parks or geovalue that can attract geologically importantand interestingtosocieties. As examples, hot water springs of Tuzla geothermalarea, ancient granite columns ofKestanbolu-Yahya Çavuşvillage and opal pit of Yenice village are taken as examples. It is also emphasized thatbesides the areas highlighted, all other possible areas have their own specific conditions and that ignoring theseconditions may cause permanent damages to the area. Earth science museum are also important institutions thatwill contribute to the discovery and introduction of these fields. As a way of preserving areas that are both scientificand tourist attraction, we have also listed our views on the importance of opening up and exploring to public andthe negativity of this activity. According to the first results, while the Tuzla Geothermal field could be used with a fewsimple arrangements but Kestanbol and Yahya Çavuş villages could not be used for the purpose of geotourism withits current state of the fields.

Abstract: The Akhüyük geothermal field, which is the study area, is located in the southwest part of the CentralAnatolian Volcanic Complex. Akhüyük travertine in the study area is a fissure-ridge type travertine formed as a resultof sedimentation of thermal waters reaching the surface along a fault line parallel to the Tuzgölü Fault Zone. Allrock samples of study area are composed of calcite mineral in whole rock XRD examination. According to the XRFanalysis results of the same samples, all samples are composed of about 90% of Ca element and this Ca element isaccompanied by Mg, S, Sr and K elements. Surface temperatures of water samples taken from different sources inthe study area vary between 17-35 °C, pH values are 6.6-6.9 and electrical conductivities (EC) are between 5600-47700 μS/cm. According to the Scholler diagram of the water samples collected from the study area, the waters arefed from the same source. The ion distributions of the water samples are Na+K>Ca+Mg and Cl+SO4>HCO3+CO3according to the cations and anions, respectively and consist of Na-Cl type water. Mineral saturations in measuredtemperatures during water sampling indicate that calcite, aragonite and dolomite minerals are generally formed byprecipitation in the thermal waters. According to the generated three-dimensional conceptual model of the field, thebedrock of the area is the Paleozoic Niğde Group, the heating system is composed by the Üçkapılı Granodiorite and geogradyan as it is in the Central Anatolian Volcanic Complex. Reservoir rock is the limestones belonging to GökbezFormation and the cover rocks are the Akhüyük travertines with the Pleistocene-Holocene sediments. 

Abstract: The 90 km long and N50°-60°W oriented right lateral Şemdinli Yüksekova Fault Zone (ŞYFZ) is locatedat the southeast of the EACP. The most prominent morphotectonic structure of the ŞYFZ is the Yüksekova Basin thathas a long axis striking in NW-SE direction with a length of 38 km and the maximum width of 10 km. In this study,morphometric indices were used to investigate the uplift characteristics of the basin. According to the Mountainfront sinuosity (Smf) and the ratio of valley-floor width to valley-height index (Vf) calculations along the mountainfronts on the northern and southern margins of the Yüksekova Basin, the faults that delimit the basin margins havehigh activity, and the uplift rate is not less than 0.5 mm /yr. Spatial distribution of the m/n values of the drainageareas reveals that the ŞYFZ have driven the rock uplift around the basin rather than the large-scale lithosphericprocesses. The integral analysis (chi= χ) of the tributaries in the drainage areas located close to the faults thatdelimit the Yüksekova Basin indicate that the uplift rate of the basin changes over time regardless of the m/n ratio.The integral analyses of lithological units, which are resistant to erosion around the basin, reveal that uplift rate hasbeen changed four times.