THE MCEWAN LAKE FAULT - GRAVITY EVIDENCE FOR A NEW STRUCTURAL ELEMENTOF THE KAPUSKASING ZONE

The Chapleau block, the largest uplifted crustal block within the Kapu skasing zone, continues, after sinistral offset of about 20 km, for a further 60 km to the southwest of Chapleau. This newly discovered exte nsion, referred to as the Pineal Lake block, terminates to the west in a north-south-trending, west-verging thrust, named the McEwan Lake fa ult. New gravity data suggest that the fault has a vertical displaceme nt of at least 5 km, a dip of about 25 degrees E, and a length of at l east 30 km. It is not known whether the fault crosscuts the Kapuskasin g structure, in which case it may represent a younger thrusting event, or represents a southerly extension of the Saganash Lake fault that b ounds the northwestern side of the Kapuskasing zone in the Chapleau ar ea.