Gold mineralization during greenhouse gas fixation: a booklet summary of research on Au-bearing listwanite in the Atlin area, northwestern British Columbia

Abstract

Listwanite (carbonate-altered serpentinite) is commonly spatially associated with gold mineralization; it also represents a natural analogue to mineral carbonation, a type of carbon dioxide sequestration. Our studies have resulted in a better understanding of listwanite associated lode-gold deposits and will aid in the design of industrial processes aimed at permanently and safely storing anthropogenic carbon dioxide. Mapping and sampling at Atlin, BC shows that listwanite-alteration is localized along a penetrative fracture system within the ultramafic body and extends up to tens of metres into intact wallrock. Petrography and geochemistry indicate carbonate-alteration proceeded via a three-stage reaction sequence. Serpentinite was converted to magnesite + serpentine which was then converted to magnesite + talc and finally to magnesite + quartz. The overall mineral transformation is the same as proposed industrial carbonation reactions and was accomplished without the alteration of non-volatile chemical species. Geochronology and stable isotopes have helped define the source of carbon dioxide and the constrained the timing and duration of the alteration. Volume changes associated with alteration may play a role in the generation of permeability in advance of carbonation reaction fronts. ln addition, we have modeled magnetic susceptibility as a proxy for listwanite-alteration that has aided in the mapping out of the permeability structure of these systems.