Stratigraphy and structure of Archean lode gold deposits in the southeastern Rice Lake greenstone belt, southeastern Manitoba, Canada

Xiaohui Zhou, University of Waterloo, Earth and Environmental Sciences, Waterloo, ON, Canada, Shoufa Lin, University of Waterloo, Department of Earth and Environmental Sciences, Waterloo, ON, Canada and Scott D Anderson, Manitoba Geological Survey, Winnipeg, MB, Canada

Contact First Author: Xiaohui Zhou; xiaohui.zhou@uwaterloo.ca

Previously Published Material: I reported part of the study as a poster at the Manitoba Minerals and Mining Convention 2014 and as an oral presentation at the Canadian Tectonic Group meeting 2014. Currently they are not under review or accepted by any scientific journal yet.

Abstract ID#: 35629

 

English Abstract:
The Central Manitoba and Ogama-Rockland gold deposits are located in the southeastern portion of the Archean Rice Lake greenstone belt in the Uchi Subprovince of the western Superior Province. These two deposits were investigated in the aspects of host-rock stratigraphy, deformation structure and vein systems through detailed bedrock mapping. Four generations (G1–G4) of deformation structures are recognized in the study area based on overprinting relationships.

The Central Manitoba deposit is hosted by quartz veins in feldspathic wacke, basalt and gabbroic sills within the Bidou assemblage of the Rice Lake belt. Stratigraphic sequence of host rocks is typically south facing. Auriferous massive quartz veins are dominantly hosted by west-trending dextral G4 shear zones. Free gold is present in contacts with quartz, pyrrhotite and tellurobismuthite. Chlorite-sericite alteration is typically associated with mineralization.

The Ogama-Rockland deposit is hosted by quartz (-carbonate) veins in tonalite of the Ross River pluton (~2724–2728 Ma). Three vein sets (V1–V3) were identified based on crosscutting relations. Auriferous massive V3 veins were likely emplaced late during the G4 shearing, and are hosted by a conjugate set of north-to-northeast–trending sinistral shear zones and west-to-northwest–trending dextral shear zones. Free gold and minor gold inclusions are present within fractured pyrite, chalcopyrite and quartz. Chlorite-carbonate-sericite alteration is common. Mutual crosscutting relationships, gradational transitions and quartz segregations in the center of aplite dikes suggest a close temporal and possibly genetic relationship between quartz veins and aplite dikes.

In spite of contrasting host rocks, ore style and alteration, the two gold deposits share identical host-rock structure and structural timing of mineralization, indicating that gold mineralization shares a similar structural setting.

Back to: Mineral Deposits and Ore Minerals I