Temporal and spatial radiogenic heat production rate of granitic plutons from the Eastern Pontides Orogenic Belt, NE Turkey: Constraints for the geothermal resources

Abstract

The evaluation of the geothermal potential of the granitic rocks is important in long-term sustainable renewable energy projects due to increasing energy demand. The Eastern Pontides Orogenic Belt in NE Turkey contains a variety of granitic plutons changing in age, size, and composition. In this paper, we discussed the temporal and spatial distribution of radiogenic heat production by using the contents of heat-producing elements (U, Th, K) of the granitic plutons. The average U, Th, and K concentrations for the granitic plutons are 2.97 ± 0.95 ppm, 13.48 ± 3.48 ppm and 2.69 ± 0.47 wt% for Paleozoic plutons, 1.83 ± 0.98 ppm, 8.58 ± 5.10 ppm and 1.77 ± 0.80 wt% for Jurassic plutons, 5.24 ± 1.64 ppm, 26.02 ± 6.43 ppm and 3.17 ± 0.49 wt% for Cretaceous plutons, and 3.82 ± 0.90 ppm, 15.79 ± 4.27 ppm and 2.88 ± 0.40 wt% for Eocene plutons, respectively. Radiogenic heat production rates are 1.43–2.73 µW/m3 for Paleozoic plutons, 0.74–1.70 µW/m3 for Jurassic plutons, 0.66–6.28 µW/m3 for Cretaceous plutons and 1.15–5.22 µW/m3 for Eocene plutons. The studied plutons were classified as low- to moderate heat-producing granitoids. However, some Cretaceous and Eocene granitic plutons with radiogenic heat production values of 5.22–6.28 µW/m3 are considered as high heat-producing granitoids. The thermal indications in the region can be related to radiogenic heat generation and the neotectonic activity of the region. Considering the large volume of the Cretaceous- and Eocene- aged granitic plutons in the Eastern Pontides Orogenic Belt, the moderate to high radiogenic heat production of the granitic plutons in some areas has a significant geothermal impact and can be considered as the potential of enhanced geothermal systems for the future energy demand of the region.