Geothermal exploration and geological mapping at Seltún in Krýsuvík field, Reykjanes Penisula, SW-Iceland

Abstract

Krýsuvík is one of the high-temperature geothermal areas in the Reykjanes peninsula in southwest Iceland. Seltún is a small field within the Krýsuvík area where the geothermal activity is intense. The geothermal field has not been utilised, but a detailed study of the field has been undertaken. Although this mapping exercise was part of the UNU geothermal training, it was also a contribution to the mapping and study of the area. Both geology and hydrothermal alteration were mapped, resulting in two separate maps: a geological map and a geothermal map. Surface manifestations were also mapped to delineate upflow zones that could serve as a basis for a geothermal model that could answer questions like that of temperature reversal at around 300 m depth in many wells in the area. The surface alteration and manifestations were found to be of linear distribution trending in the same direction as the major fault system and fissure swarms. The model suggests structurally controlled upflow zones. The model also suggests a solution to the temperature reversal in many wells in the Krýsuvík area.