Structural history of the Beaverlodge area [Saskatchewan]

The Precambrian rocks of the Beaverlodge area, northern Saskatchewan, are divisible into 2 broad units, (1) the highly folded and extensively granitized Tazin group unconformably overlain by (2) the synclinally folded Athabasca series. These rocks are cut by 3 major faults, and evidence is presented to show that 2 of these, the St. Louis and ABC faults, are probably extensions of the same break despite a bend of 80 degrees between the 2 prolongations. Age of faulting is discussed and it is concluded that much, if not all, of the fault movements occurred in post-Athabascan time. A method is described by which quantitative estimates of the net-slip on the St. Louis-ABC fault are calculated. Movement is normal, the net-slip roughly 4 mi. A minimum normal dip-slip component of movement on the Black Bay fault is found to be of the same order of magnitude. A 4-stage tectonic history of the area is presented in which 2 periods of crustal shortening alternate with regional, then localized epeirogenic movements. Wherever possible, idealized block diagrams are used to illustrate tectonic events. A table summarizes the tectonic history of the area.

This record provided courtesy of AGI/GeoRef.