Kamil Erkan

The Menderes Massif in western Anatolia is a large metamorphic core complex that formed in the back arc of the Aegean subduction zone. Geological and geodetic studies show that extension has occurred almost uniformly since the cessation of continental collision at c. 30 Ma. In this study, we used 2D numerical modeling informed by measurements of abundances of radioactive heat producing elements in exhumed Menderes metamorphic rocks (gneiss, schist, migmatite, granite) to investigate the effect of variation in vertical distribution of crustal radioactivity on the style of extensional deformation during core complex evolution. We assumed four different scenarios with the same total crustal radioactive heat production but fractionated differently between the upper and lower crust: 0%, 25%, 50%, and 62.5% of the total crustal radioactivity located within the thickened lower crust. Our numerical experiments reveal that lower crustal radioactivity has a major effect on the temperature (T) of the lower crust and hence its geodynamic evolution. We observed significant partial melting and core complex development only in the scenarios with fractions of 50% or more. The results are nearly independent of upper crustal radioactivity. The elevated radioactivity levels and therefore T of the lower crust drives partial melting, which in turn results in lower viscosity and enhanced crustal flow. According to these results, the lower part of the thickened orogenic crust in western Anatolia must be highly radiogenic in order for the formation of the observed core complex structure.

The Thrace Basin in northwestern Turkey is a deep Eocene–Oligocene hydrocarbon-bearing sedimentary basin. The basin has potential for geothermal energy utilization in the future due to its favorable geological conditions. In this study, we combined the available bottom hole temperature (BHT) data from 70 points with the thermal conductivity and radiogenic heat productions of the basin formations, and generated a detailed thermal model of the northern part of the basin. For heat flow determinations from the BHT data, we applied Bullard’s thermal resistance method on formation thermal conductivities and thicknesses. The results give an average surface heat flow of 65.8 ± 11.3 mW/m². We obtained high heat flow values (75–80 mW/m²) in the eastern and western sides, and the central part of the study area. These relatively high heat flow values can be explained by the combined effect of basement topography and the variations in the radiogenic heat production of the basement rocks. The calculated subsurface temperatures in selected hydrocarbon fields vary in the range of 45–64 °C at 1 km depth, 99–136 °C at 3 km depth, and 155–208 °C at 5 km depth as a result of local variations of the surface heat flow and formation thermal resistances. These variations in subsurface temperatures can have significant effects on the cost of geothermal energy production in future.

This study aims to develop an optimization model for obtaining the maximum benefit from wind power plants (WPPs) to help with reducing external dependence in terms of energy. In this sense, design of experiment and optimization methods are comprehensively combined in the wind energy field for the first time. Existing data from installed WPPs operating in Turkey for the years of 2017 and 2018 are analyzed. Both the individual and interactive effects of controllable factors, namely turbine power (MW), hub height (m) and rotor diameter (m), and uncontrollable factor as wind speed (m/s) on WPPs are investigated with the help of Box-Behnken design. Nonlinear optimization models are utilized to estimate optimum values for each decision variable in order to maximize the amount of energy to be produced for the future. Based on the developed nonlinear optimization models, the optimum results with high desirability value (0.9587) for the inputs of turbine power, hub height, rotor diameter and wind speed are calculated as 3.0670 MW, 108.8424 m, 106.7597 m, and 6.1684 m/s, respectively. The maximum energy output with these input values is computed as 9.952 million kWh per unit turbine, annually. The results of this study can be used as a guideline in the design of new WPPs to produce the maximum amount of energy contributing to supply escalating energy needs by more sustainable and clean ways for the future.

High quality temperature-depth information from boreholes that are 100-m or deeper are used in geothermal studies and in studies of climate change. Electrical wireline tools with thermistor sensors are capable of measuring borehole temperatures with mK resolution. Use of surface readout mode allows analyzing the thermally conductive state of a borehole which is especially important for climatic and regional heat flow studies. In this study, we describe the design of a portable temperature logging tool that uses four-wire resistance measurement method. The four-wire method enables eliminating cable resistance effects thus allowing mK resolution for obtaining temperature data at depth. A preliminary two-wire model of the system is also described. The portability of the tool enables one to collect data from boreholes down to 300m, even in locations with limited accessibility.

The Qinghai-Tibetan plateau (QTP), also known as the Third Pole and the World Water Tower, is the largest and highest plateau with distinct and competing surface and subsurface processes. It is covered by a large layer of discontinuous and sporadic alpine permafrost which has degraded 10% during the past few decades. The average active layer thickness (ALT) increase rate is approximately 7.5 cm·yr⁻¹ from 1995 to 2007, based on soil temperature measurements from 10 borehole sites along Qinghai-Tibetan Highway, and approximately 6.3 cm·yr⁻¹, 2006–2010, using soil temperature profiles for 27 monitoring sites along Qinghai-Tibetan railway. In this study, we estimated the ALT and its AL thickening rate in the northern QTP near the railway using ALOS PALSAR L-band small baseline subset interferometric synthetic aperture radar (SBAS-InSAR) data observed land subsidence and the corresponding ALT modeling. The InSAR estimated ALT and AL thickening rate were validated with ground-based observations from the borehole site WD4 within our study region, indicating excellent agreement. We concluded that we have generated high spatial resolution (30 m) and spatially-varying ALT and AL thickening rates, 2007–2009, over approximately an area of 150 km² of permafrost-covered region in the northern QTP.

Determination of the conductive heat flow in western Anatolia has broad implications in many areas, including studies on the present-day extensional tectonic activity and assessments of the geothermal resources in the region. In this study, high-resolution equilibrium temperatures from 113 boreholes with depths of ~100 m were analyzed for determination of the conductive heat flow. Thermal conductivities were either determined by measurements on outcrops or estimated using lithologic records. By a detailed analysis of temperature–depth curves, a total of 55 sites were selected as being useful for further conductive gradient/heat flow calculations, while the remaining 58 sites were abandoned due to hydrological effects on temperatures. Heat flow values with formal errors were calculated for 24 sites where rock thermal conductivity information is available. Due to the shallow depths of the investigated boreholes and uncertainties in thermal conductivity information, the results include a large accumulated error. A preliminary heat flow map is generated using the results of this study and a previous study in the southern Marmara region. Elevated heat flow values of 85–95 mW m-2 are observed in the coastal areas, including peninsular parts of Çanakkale and Izmir. The central part of the Menderes Massif also shows elevated heat flow values, the highest values (>100 mW m-2) being in the northeastern part of the Gediz Graben near the Kula volcanic center. Moderate heat flow values of 55–70 mW m-2 are observed in the eastern part of Çanakkale, central part of Balıkesir, northwest of Manisa, and northeast end of Bursa including Yalova. Some of the observed moderate values may be related to unconstrained near surface phenomena due to shallow depth of measurements. Towards the south of the study region, moderate heat flow values are also observed in Muğla. Previously reported regional heat flow values exceeding ~120 mW m-2 is not observed in the region. The heat flow values reported in this study are comparable to the previously reported values in the Aegean Sea, as the two regions form the back-arc section of the Hellenic subduction zone.