Mesoarchean western margin of the Superior Craton in the Lake Winnipeg area, Manitoba

The west-facing Lewis-Storey rift assemblage of arkosic grit, quartzite, komatiite, and iron-formation rests unconformably on ca. 3 Ga basement in eastern Lake Winnipeg. Regional correlations suggest a probable ca. 2.9 Ga age for the sequence, which may mark the Mesoarchean western margin of the North Caribou terrane. The rift package is structurally overlain by the east-facing Black Island assemblage of submarine tholeiitic and calc-alkalic basaltic rocks and the <2.706 Ga arkosic Hole River sequence. Prominent, northwest-trending, dextral D1 shear zones, thought to be responsible for tectonic juxtaposition of the major tectonostratigraphic assemblages, are overprinted by S2 crenulations and the D3 Seymourville shear zone that accommodated 7 km of dextral strike slip. Possible linkages between these tectonic elements and those of the Rice Lake and Wallace Lake belts to the east are being explored through geochemical, geochronological, and structural studies. CURRENT RESEARCH RECHERCHES EN COURS 2001 Article Article Titles Titres Purchase Information Information pour acheter 2001-C16 J.A. Percival et al. 1 1 Contribution to the Western Superior NATMAP Project 2 Manitoba Geological Survey 360-1395 Ellice Avenue Winnipeg, Manitoba R3G 3P2