RB-SR CHRONOLOGY OF THE RAINY LAKE ARCHEAN GRANITOID BATHOLITH, WABIGOON BELT, NORTHWESTERN ONTARIO

In the Lake Despair area, the Rainy Lake batholithic complex subdivides into three syntectonic, foliated to migmatized granitoids (Jackfish Lake Complex, Northwest Bay Complex, Footprint Lake Gneiss). Field relationships predate the high level, late tectonic, granitoid stocks lying within adjacent superacrustal rocks. The three units give a 10 point York I Rb/Sr whole-rock isochron age of 2616 plus or minus 66Ma. This age is statistically indistinct from a pooled isochron for seven late tectonic Wabigoon stocks. one geochemical outlier, from Footprint, lies on a 3241 Ma reference line, interpreted as a pseudoisochron. 35 refs.