OUTLINE OF THE ECONOMIC GEOLOGY OF KALGOORLIE, WESTERN AUSTRALIA.

The rich Golden Mile deposits at Kalgoorlie occur at the top of an Archaean mafic volcanic pile, overlain by the products of felsic volcanism and sedimentation. The principal host rocks are carbonated greenstones, the lithologies of which have been the subject of various interpretations. Though all appear to be concordant, some may be intrusive; others obviously are extrusive. In effect, a series of repetitive dominantly mafic volcanic cycles is represented, each commencing with a basal ultramafic and becoming generally less mafic. Each cycle concludes with an episode of gold deposition, apparently coeval with deposition of mostly cherty and/or carbonaceous sediments and minor felsics. The Golden Mile deposits appear to represent the culmination of these auriferous episodes.