Mineralogy and geochemistry of the Murdock Creek intrusion, Kirkland Lake, Ontario.

Abstract

The Murdock Creek intrusion, immediately southwest of Kirkland Lake, Ontario, in the southern part of the Abitibi belt, is a member of a suite of late Archean ($\approx$2680 Ma) syenitic intrusions located within and adjacent to the Kirkland Lake-Larder Lake fault zone (KLF), which host virtually all of the gold mineralization in the Kirkland Lake camp. An early crystallizing mafic margin consisting of clinopyroxenite, meladiorite, melamonzodiorite, and melasyenite encloses an extensive felsic core of alkali-feldspar syenite. A coeval hornblendite unit with lamprophyric affinities, intrudes throughout the pluton and most closely approximates the mantel-derived liquids which differentiated to produce the suite of syenitic intrusions and possibly potassic alkaline extrusive rocks of the Timiskaming Group. The intrinsically oxidized nature of the pluton suggests a genetic link with gold mineralization in the Kirkland Lake camp. (Abstract shortened by UMI.)