Chemistry of Fumaroles and Hot Springs in the Torfajökull Geothermal Area, South Iceland

The preliminary results of a geochemical survey of fumaroles and hot springs in the Torfajökull geothermal area, South Iceland, are presented. The total gas content in fumarole steam ranges from about 20 to roughly 25,000 mmole/kg, with carbon dioxide as the main component. Gas geothermometers indicate subsurface temperatures of about 300°C in the northern, western, and central parts of the area, and as high as 350°C in the southern and southeastern parts of the field. Mercury concentrations in steam range from 20 to 600 ng/kg, generally highest in the southeastern part. The thermal spring waters are mostly of the bicarbonate type in the southern part of the field, and of the sodium chloride type in the northern part.