Abstract
The Mount Meager Complex [recent publications have misnamed the complex Meager Mountain; Mount Meager is the accepted name of the mountain] of Pliocene to Recent age contains volcanic rocks ranging in composition from basalt to rhyolite. Products of three periods of volcanism dominate the complex; early and late periods of rhyodacite bound a middle episode of andesite. In the early episode rhyodacite tephra and flows, from <1.9±0.2 Ma to > 1.0±0.1 Ma, covered remnants of a basal breccia and overlying dacite flows on the southwestern edge of the complex. Products from the middle episode of andesite volcanism, from 1.0±0.1 Ma to 0.5±0.1 Ma, underlie the southern and central parts of the complex; The Devastator was their principal source. The late episode of rhyodacite volcanism, from 0.1 ±0.02 Ma to 2340±50 years B.P., produced rhyodacite flows, tephra and lava domes from vents in the northeastern part of the complex. The vent at the 1650 m (5400 foot) level on the northeast flank of Plinth Peak is the source of the Bridge River tephra. Meager and Pebble Creek hot springs issue from the Mesozoic basement near vents.