Türkiye Jeoloji Bülteni

Abstract: The Reşadiye (Tokat) geothermal field is located in the northern part of the right-lateral North AnatolianFault Zone. Geothermal waters at temperatures between 48-52°C from this geothermal field are currently usedmostly in hotels, pools and bathrooms and provide significant tourism potential for the region. The area where thegeothermal sites are located includes a ~NW-SE trending fissure-ridge type travertine with a length of about 600meters. Approximately 500 meters south of the geothermal field and parallel to the Kelkit River, the active segmentof the North Anatolian Fault Zone comprises the Kelkit Valley fault segment extending N72°W. The average strikedirection of Reşadiye fissure-ridge type travertine is around N33°W. There is an angle of 39° between the mastertrend of NAFZ and the direction of the Reşadiye fissure-ridge travertine. This 39° angle between the extensionalcracks in the fissure-ridge travertine and the NAFZ is compatible with extensional fractures developing in wellformed strike-slip faults at an angle of ~45° with the master fault. U/Th determination of two samples from bandedtravertines from the travertine deposits yielded ages of 7,563 and 12,529 years. Combined with other evidence, thesamples indicate an opening rate of 0.093 mm/year for the Reşadiye geothermal travertine field.

Abstract: All research on neotectonics in Turkey accepts Western Anatolia as a distinct, separate region in which theneotectonic period began in Upper Oligocene, according to some researchers, and in Upper Miocene according toothers, and has continued up to the present day. The region expanded in a north-south direction during this processgrabens were formed, generally with an east-west orientation. In this interpretation, the normal faults causing a north-south oriented extension are proposed to have detachmentfault characteristics. As observed in field studies, fold and strike-slip faults developed during this period but thesedimentary basin geometry and dimensions cannot be explained by a simple graben system. There are outliers interms of the chemistry of volcanism in outcropping areas. Explanations for these inconsistencies have yet to be foundand those based on time-space-causal relationships related to evolution in the neotectonic period do not go beyondabstract modelling. In this presentation, a different model is suggested with the aim of solving controversies in the models proposed todate. The recommended method is based on the neotectonic evolution explanatory principle of revealing the currentdeformation form in a region in order to understand its neotectonics, and then working backwards from today. Currently, the tectonic region defined as Western Anatolia encompasses an area between the northwest-southeastoriented Bursa-Eskişehir-Afyon Fault Zone and the northeast-southwest oriented Muğla-Afyon Fault Zone in the east,extending in a sideways V shape towards the west. Moving toward the west, the region is separated in intraplateblocks due to the lithological differences, paleotectonic structures and volcanism, etc. present in the region. Thedifferent movement velocities of these separate blocks cause deformation in the region. Significant factors affectingthese motions are the dimensions, velocity and direction of the blocks. With the varying motion of the blocks, normal,reverse and strike-slip faults along with extensional fractures occur along the block boundaries. In this model,different movements may be observed in different locations on the same fault plane. Again, there are parallel, coevalstructures found in the region, although they move in different directions. On the whole, block movements progresstoward the west-southwest of the region. Extensions occurring between blocks occasionally form graben geometry. According to this proposed model, the east-west oriented grabens currently observed in Western Anatolia areconcluded not to be products of north-south oriented extensions. Currently, the greatest extension is on the easternboundaries of the V-shaped block. Intensive thermal manifestations are observed north of this boundary in the KulaVolcanics and to the south in the Pamukkale region. The 10-km long fracture caused by the 1995 Dinar Earthquakeand the aseismic deformation motion at Sarıgöl both have extensional fracture characteristics.Paleomagnetism, crustal thickness, GPS data and the fault-plane solutions of earthquakes in the region supportthis model. This proposed kinematic model is thought to have been in operation about 3-4 million years before thepresent.

Abstract: This study aimed to determine the petrographic and geochemical features of the Plio-Quaternary Gözucu(Taşlıçay-Ağrı) volcanics. These volcanics have subalkaline, calc-alkaline, high-K-series and shoshonitic featuresand are composed of basalt, andesite, trachyandesite, trachydacite and dacites. The Gözucu volcanics exhibitenrichment in light rare earth elements (LREE) and large ion lithophile elements (LILE) while showing depletionin heavy rare earth elements (HREE) and high field strength elements (HFSE). The average Sr and Ba values ofGözucu volcanics are close to continental crust values (Sr-379 ppm Ba-639 ppm), which means that these rockswere contaminated by the continental crust during formation. Low Nb/La (5.13 ppm) and high Ba/Rb (16.75 ppm)ratios indicate that the contribution of sediments was more than that of fluids during the contamination process ofthe Gözucu volcanics. Positive and negative trends of major and trace elements in the variation diagrams indicatefractional crystallization and a single mantle source. The Gözucu volcanics occurred with a partial melting of thespinel-rich lithospheric mantle source with 0.1-3% partial melting in the continental arc environment after thecollision. 

Abstract: The present study deals with experimental mathematical equations that link density and porosity withdepth. After obtaining density and porosity information from three well logs scattered in the East Baghdad oil field,new empirical polynomial equations (porosity-depth, density-depth) were produced for all the geological formationsbetween the Fatha and Hartha formations. The coefficient of determination (R2) of the equations derived for eachformation ranged from 0.11 to 0.93, which was attributed to variable lithological and compaction effects. The depthinformation of (131) velocity analyses situated on the seismic lines grid covering the field was used for applying thenew equations. After the new empirical polynomial equations were applied to the whole field, porosity and densitycontour maps for the Fatha-Hartha interval were produced. The location of high porosity zones was identified andrelated to the compaction and petroleum distribution in the field.

Abstract: The study area, located in the Cappadocia Volcanic Terrain between the dextral Tuz Gölü fault and sinistralEcemiş fault, was affected by neotectonic forces and accordingly underwent volcanic activity that developed fromlate Miocene until recent years. Extrusive igneous rocks outcropping in central Anatolia around Susuzdağ (Hamurcutown, Kayseri) and Tekkedağ (Başdere town, Niğde) were mapped using an Advanced Spaceborne Thermal Emissionand Reflection Radiometer (ASTER) multispectral satellite image. Band ratio images of 9/8, (1+4)/(2+3), 6 and(1+4)/(2+3), 8, 4/6 (RGB) were constructed by taking in account ASTER bands corresponding to the characteristicFe, Al-OH and Fe/Mg-OH absorption features of rocks in the region, and the boundaries of basalt, basaltic andesite/andesite, dacite and pyroclastic rocks in the region were delineated. It was demonstrated that a band ratio of 9/8 isparticularly effective in differentiating basalt and andesite from the surrounding extrusive igneous rocks. In addition,the ferrous iron index, (1+4)/(2+3), clearly indicates dacite domes as bright pixels around Hamurcu town. Incesuignimbrite covering large areas in the region appears in darker tones than the surrounding rocks in the 4/6 bandratio image due to the fact that it has a relatively shallow absorption feature in ASTER band6. The accuracy of the resultant lithological maps generated from the first-time used band ratio images was verified by comparing the fieldsurvey and geological maps. Although there is some uncertainty in discriminating between basalt and andesite, theresultant ASTER images enable us to map extrusive igneous rocks in a cost-effective, reliable and fast manner. Themethodology used in this study can be applied for mapping igneous rocks in similar geographic locations in Turkeyand around the world.