Alfa Laval AB, Sweden

Abstract

The massive sulfide deposits of the Skellefte district are located in northern Sweden. The ores are hosted by Precambrian submarine volcanics and sedimentary rocks. Both rocks and ores have been deformed and metamorphosed, mainly to greenschist facies.Aqueous two-phase (liquid-vapor) primary inclusions in sphalerite, quartz and calcite from six mines (Rävliden, Kristineberg, Östra Högkulla, Bjurträsk, Renström and Långdal) indicate that the sulfide ores were formed under non-boiling conditions during two major stages of hydrothermal activity at temperatures of 210° and 295°C, respectively. The ore-forming fluids were CaNaCl-bearing hydrothermal solutions with a salt content of 4±2 eq. wt.% NaCl. Later recrystallization of the ores occurred at lower temperatures involving solutions with higher salinities.