Distribution of Miiuiu, Boron and Chloride Between Fie& and Altered Rocks in the Kawerau Geothermal System, New Zealand

Abstract

The partitioning of Li, B and C1 between altered rock and thermal waters in Kawerau is dependent primarily on their ability to be incorporated into the snucture of secondary minerals. Chloride rarely finds a niche in alteration minerals below 320?C and is thu highly depleted in altered rock, but enriched in the waters. Boron and Li participate in hydrothermal m i n d formation. At elevated temperatures, the mas distribution coefficient (Kw-R) bween water and rock of B is 0.2 and that of Li is c0.06, showing that B has a high tendency to be leached, while Li stays in the rock. However, at temperatures <lOO?C, the Kw-R of B and Li is the Same at 0.1, indicating that both have a similar tendency to partition into rock at low temperatures. The redistribution of other elements durjng alteration is affected by the chemical composition of the altering fluids and the original rock, and by permeability and temperature.