Buried Hydrothermal Systems: The Potential Role of Supercritical Water,“ScriW”, in Various Geological Processes and Occurrences in the Sub-Surface
Buried Hydrothermal Systems: The Potential Role of Supercritical Water,“ScriW”, in Various Geological Processes and Occurrences in the Sub-Surface Author(s) Martin Hovland, Håkon Rueslåtten, Hans Konrad Johnsen ABSTRACT It is well known that seawater that migrates deep into the Earth’s crust will pass into its supercritical domain at temperatures above 407°C and pressures above 298 bars. In the oceanic crust, these pressures are attained at depths of 3 km below sea surface, and sufficiently high temperatures are found near intruding magmas, which have temperatures in the range of 800°C to 1200°C. The physico-chemical behaviour of seawater changes dramatically when passing into the supercritical domain. A supercritical water vapour (ScriW) is formed with a density of 0.3 g/cc and a strongly reduced dipolar character. This change in polarity is causing the ScriW to lose its solubility of the common sea salts (chlorides and sulphates) and a spontaneous precipitation of sea salt...