Türkiye Jeoloji Bülteni

Abstract: Geophysical methods have been an important component of effective hydrogeologic investigations overthe Edwards aquifer in central Texas. A variety of electrical and electromagnetic methods have been used to mapstratigraphy and geologic structure and to locate buried sinkholes and caves. Geophysical methods can alsocharacterize faults and fractures in the Balcones Fault Zone (BFZ). Six exemplary case studies across the Edwardsaquifer in the Austin area show that the location of buried caves and sinkholes, and fault characterization are bestaccomplished by using a combination of 2-D and 3-D resistivity imaging and self-potential methods. Additionalgeophysical methods, such as ground penetrating radar, induced polarization, and seismic refraction tomographycan be also used to characterize faults and karstic features. It is noted, however, that successful application of themethods is site dependent; applications in other karstic regions could respond differently to different geophysicalmethods and select  different primary geophysical methods.

Abstract: Central Anatolian basins, which are boundend by the Pontides in the north and the Kırşehir and Torostectonic blocks to the south-southeast, geologically important structures in the region with sediment accumulationsup to the present day to comprises subduction to collusion process (Senezoyik) in northern segment of the NeotethysOceanic litosphere beneath to the Pontides. Within the scope of this study, these depositional structures, which aregeographically located in Ankara and in the vicinity and classifield as the Kırıkkale-Bala, Alcı-Orhaniye, Haymanaand Tüzgölü basins in litreture. Although sedimentary deposition stages, lithological properties and sourcecharacteristics show great similarities, they are considered as different basins in terms of their today’s geographicalpositions. In this study, these basins were examined with gravity and magnetic methods and information abouttheir structures in the depths of the earth were obtained. Especially, the Haymana and Kırıkkale-Bala basins werefound to have the thickest sediment depositions in the region (about 8-9 km). The deep structures of the basins weremodeled by gravity method and their possible connections with each other were determined. In particular, it has beentried to explain the ongoing debates in the literature that Tuzgölü and Haymana basins were the same sedimentarybasin in the past. Within the basin areas, no clear change in gravity data but high positive magnetic anomalies can be associated with the presence of volcanic units (Neogene) near beneath the surface. In addition, important datarelated to the evolution of tectonic deformation of the İAESZ on these basins have been revealed. The information ofthe basins with this depth provides new perspective related with the geodynamic evolution of the region, especiallyconsidering the tectonic blocks they surround

Abstract: In this study, Synthetic Aperture Radar Interferometry (InSAR) method is used together with fieldobservations to determine whether surface deformations occur in the region after the 5,5 Mw (AFAD) SamsatEarthquake occurred at a distance of 2.5 km from the Samsat district of Adıyaman province on 2 March 2017. Weattempted to determine the deformation of the interferogram created by analyzing two Synthetic Aperture Radar(SAR) images of the Sentinel-1A fit before and after the earthquake. As a result of the evaluation of the interferogram,a surface deformation of about 2.5 cm in the satellite view direction/Line of Sight (LoS) was observed in the region.This deformation is mostly concentrated in the northeast of Samsat town. As a result of the detailed field investigationsmade immediately after the earthquake in the region, no surface rupture occurred but surface deformations in theform of local and discontinous fissures developed in some areas. It is understood that the Earthquake developed ona fault passing through about 5 Km North of Samsat and named as Samsat Fault by TPAO. It appears that morethan 400 aftershocks following the main shock in the region concentrate roughly on a N40-50W lineament. It isnoteworthy that in the observations made in the field, the distribution of the damage has also developed along thisline in particular.

Abstract: Detailed research on the quality of the reservoir for oil research and production is very important to reducecosts because of the high cost of oil exploration and evaluation. The aim of this study is to determine petroleumreservoir rock quality of the Mollaresul formation which is composed of Jurassic-Lower Cretaceous aged limestoneswithin the Haymana-Polatlı basin. The reservoir quality of the limestones was determined by standard field studiesand laboratory analyzes, porosity-permeability analyzes and petrographic studies. In the field studies, the formationis observed as massive and stratified, and it is deposited from a shallow to deeper marine environment. According toporosity-permeability analyses, the porosity values of the formation are between 30% and 45%, and the permeabilityvalues are between 5.2 and 7.7 md. Layered, abundant cracked and karstic cavities of the formation formed a goodporosity in the formation. Although fractures and cracks in the formation greatly increased porosity, secondarycalcite, ferrous (Fe) and manganese (Mn) cement filling the fractures and cracks did not make the permeabilityas high as the porosity. In conclusion, according to the field and laboratory studies, Mollaresul formation shows amoderate reservoir rock quality.