Tracking the Wakeham Group volcanic rocks and associated copper-iron oxide hydrothermal activity from La Romaine eastward, eastern Grenville Province, Quebec

Abstract

The last field season of the Targeted Geoscience Initiative Eastern Grenville Transect in Quebec unveiled a < 10 km wide by 50 km long southeastern extension of the Wakeham Group, host to an extensive cupriferous hydrothermal system. The supracrustal rocks consist of granulite-facies metasandstone, 1.5 Ga lapillistone, amphibolite, marble, and calc-silicate rock enclosed within a metamorphosed, 1.5 Ga Pinwarian subvolcanic batholith. High-grade metamorphism in this belt would traditionally be seen as an impediment to mineral exploration. However, we have recognized and traced an extensive zone of aluminous gneiss that records strong hydrothermal leaching of metavolcanic units. Amphibolite occuring structurally above and likely serving as a caprock contains garnetite, diopsidite, and hornblendite and provides an effective guide to the site of fluid discharge and mineralization.Anumber of showings were discovered; their systematic occurrence, in a structural and stratigraphic sense, suggests that, although this supracrustal belt is of modest size, it should be explored.

Migmatitic structures and solid-state diapirism in orthogneiss domes, eastern Grenville Province, Canada

“…The deposition age of the easternmost part of the Wakeham Group lies between 1600 and 1500 Ma (Larbi et al, 2003;Corriveau et al, 2003), whereas no dates are available for the deposition age of the western part (Fig. 1).…”