Geothermal resources assessment using temperature–depth relationships in the fault-controlled hydrothermal system of Aristino-Traianoupolis area, Northern Greece

Abstract Aristino-Traianoupolis area hosts one of the most significant water-dominated low-temperature geothermal fields in Greece. It is located on southwestern uplifted margin Tertiary Evros Delta molassic basin, 10 km east town Alexandroupolis (Thrace, NE Greece). The upper hydrothermal system Aristino Geothermal Field (AGF), promising continental Greece, contains fluids with temperatures ranging from 51 to 99 °C, within a series overlapping aquifers at very low depths (100–430 m). main anomaly for higher than 90 °C covers an 6 2 , maximum prospected depth 500 m below ground surface. scattered regional exceeds 50 and characterized by excessively high abruptly changing thermal gradient (42 450 °C/km) heat flow (80–800 mW/m ), that are both typical fault-controlled system. Since 1993, AGF has undergone non-systematic investigation, emphasis low-depth (100–500 m) drilling. This paper provides, first time, synthetic detailed evaluation all available temperature data gathered last 25 years. steady-state logs reveal dominant role conduction system, accompanied, cases, rapidly abnormally gradients (100–450 °C/km), triggered, probably, deeper temperature. hypothesis also supported applied chemical geothermometers, which suggest initial fluid 140–150 hydrochemical characteristics hosted investigated reservoir (ignimbrite) extrapolated conductive temperature–depth profiles. lower widespread medium enthalpy should extend 500–1000 volcanics expected Eocene limestones basal clastic sequence have filled basin. Nevertheless, these assumptions need be verified appropriate investigations new drillings greater 600–700 m, would confirm presence productive reservoir.