Abstract

The highest grade orebody in the Dome mine is a steeply dipping 500 m long, 550 m high, and 3.5 m wide banded quartz-fuchsite vein (QFV) accompanied by subsidiary veins in the adjacent wall rock. The QFV is located in a subvertical zone of carbonatized komatiite near a slate unit and is composed of relatively unstrained massive quartz and strained ribbon quartz. Fuchsite and chlorite are the main ribbon components. Native gold, galena and tellurides are typically associated with ribbon quartz, whereas massive quartz is usually low grade.The quartz–fuchsite vein system is coeval with the regional penetrative deformation. Reverse oblique-slip faulting together with an intricate interplay between intermittent variations of the deviatoric stress regime and strain refraction due to layer anisotropy explain the overall anatomy of the vein system. The regional compressive stress regime and the syntectonic wall-rock alteration created the favorable requirements for the combined shear and hydraulic fracturing that led to vein formation.Massive quartz was deposited during prolonged episodes of vein growth, whereas ribbon quartz was emplaced in the course of repetitive and brief periods of crack-seal vein growth. The systematic association of high-grade ore with ribbon quartz suggests a genetic link whereby gold deposition is attributed to small pressure drops accompaning the crack-seal mechanism of vein growth. Thus, gold was introduced along with the bulk of the quartz.

You do not currently have access to this article.