The distribution of geothermal fields on the Juan de Fuca Ridge

Abstract

Near bottom water temperatures were mapped along 400 km of the strike of the Juan de Fuca Ridge as part of a combined Sea MARC/Seabeam experiment to image the variability of morphology and structure along a spreading center segment. The water temperature data collected by a continuously towed thermistor chain, in addition to salinity data, indicate that there are four geothermal areas spaced at distances of 100 km from each other south of the Cobb propagator and one field just to the north of the propagator on the Endeavor Ridge segment. Each thermal region is located above a morphological dome on the spreading center. These domes are an average of 100–200 m shallower than the rest of the axis. The structure of bottom water suggests that the geothermal regions are on average 20 km long and that the heat from these fields raises the temperature in the water column by a minimum of 0.06°C up to 300 m above the bottom. Two simple models are used to estimate the heat flux associated with these features.