The Eldvdrp High-Temperature Area, SW Iceland. Geothermal Geology of First Exploration Well

Abstract

Surface geology and resistivity data show that the eruption episode of 2100-2500 years ago in the Eldvorp region causes a downflow of colder groundwater in the northern part of the "fissure swarm" while an upflow characterizes its central part. The first exploration well EG-2 disects two vertical dyke feeders; the older one, a dolerite, dates back to less than 12000 yrs while the younger one is the feeder to the 2150 yrs Eldvorp eruption. Hydrothermal alteration pattern shows that these vertical provide the main upflow channels of the Eldvorp system. A study of the deposition sequence in veins and vesicles shows evolution stages from a low-temperature to a high temperature system. The last deposition suggests that the system is showing some cooling below 1200 m depth.