Spatial and temporal relationship between intrusive rocks and gold mineralisation in the Miller Dyke Complex, Abitibi greenstone belt, Ontario, Canada

Abstract

The Miller Dyke Complex (MDC) is located 15 km south of the Kirkland Lake gold camp. It consists of a series of narrow, structurally controlled dykes, that range from felsic to mafic in composition, and are spatially associated with Au, ± Cu, ± Mo mineralisation. The MDC provides an excellent locality for a careful study of the igneous petrology and the different alteration assemblages associated with the mineralisation. The study is focused on the metasomatic processes related with alkali elements. It is shown that strong sodic alteration has a strong influence on the textural, mineralogical, and geochemical features of these rocks. Previously undescribed textures and mineralisation styles are documented, as well as the existence of a Paleoproterozoic hydrothermal reactivation event with metal deposition or remobilisation. The relationship between the alkali metasomatism and gold mineralisation is discussed within the regional context of the Abitibi greenstone belt.