The Use of Stable Isotopes of Oxygen and Hydrogen in Geothermal Studies in Iceland

Abstract

Since 1986 extensive oxygen and hydrogen isotope analyses have been carried out on natural waters in Iceland and the relationship between the isotope ratios studied. Prior to this, the deuterium content of the mean annual precipitation in Iceland had been mapped, allowing deuterium to be used extensively as a tracer to delineate regional movement of groundwater, including geothermal water. As the groundwater can originate from different climate regimes, the deuterium map of the present-day precipitation should be used with care to obtain information on the recharge areas to geothermal systems. however, the relationship between and FD is well known in present-day precipitation, it should be possible to recognize groundwater that has fallen as precipitation under climate conditions differing from those of today. In this contribution a new - 6D relationship of Icelandic cold groundwater is defined as = when is (6D 2-76 and as 8 for lighter precipitation.