Geothermal mapping in the Krýsuvík geothermal field

Abstract

This report describes the results of a mapping exercise of surface geothermal manifestations and the main structures of the Hveradalir field in the Krýsuvík area, SW Iceland. The main aim of this project was to map the geothermal manifestations in order to find out if a correlation existed between geothermal, volcanic and tectonic features in this field. The main manifestations mapped include fumaroles and steaming grounds, mud pits, hot, warm and cold springs, and hot and warm grounds delineated by 50°C isotherms and 15°C isotherms, respectively. The manifestations are seen to be controlled by NE–SW oriented faults. The lithology of the study area includes three lithological units. A hyaloclastite unit belonging to the youngest Sveifluháls hyaloclastite formation is by far the most voluminous unit and hosts all the geothermal manifestations. This hyaloclastite unit is from the last glacial period. Mapable lava patches of much younger age, either of late interstadial or very early Holocene age, are found exposed on top of the hyaloclastite. Of younger age still is a scoriacious tephra and earth ejected from explosive craters of early Holocene age.