Geothermal gradients and seismicity correlations in the Biga Peninsula (NW Türkiye) based on Curie point depths

The Biga Peninsula has hot springs with geothermal temperatures varying between 40°C and 175°C. In this study, we investigate the regional temperature distribution and change in radiogenic heat production in the Biga Peninsula. We use EMAG2 magnetic data to estimate the Curie point depth (CPD). Our findings show that the CPD in the region varies between 9 km and 17 km. We also calculated the geothermal gradient and heat flow values based on the CPD data. which range between 92.9 and 141.6 mWm-2. Additionally, we also obtained values for zo, zt, and zb from the power spectrum and calculated 1D geothermal gradient change for examined blocks. The resulting equations are: zt = z80°C, zo = z350°C, and zb = z580°C. These equations enabled us to propose a new formula to calculate the CPD. We also obtained the Conrad discontinuity depth (zc = z680°C) in the Biga Peninsula. Furthermore, we prepared 2D heat flow and temperature profiles along three sections to investigate the relationship between heat changes and earthquake focal distributions. The results indicate that seismicity is high in the southwest of the Biga Peninsula, which has a high CPD, high heat flow value, and shallow Conrad discontinuity. Keywords: Biga Peninsula; Curie point depth; geothermal gradient; heat flow unit; Conrad discontinuity