PALEO-GLACIER RECONSTRUCTION IN SOUTHWESTERN BRITISH COLUMBIA, CANADA: A GLACIOVOLCANIC MODEL

Volcanic rocks erupted within glacial environments offer powerful paleoenvironmental insights. These glaciovolcanoes and their deposits serve as proxies that inform on the paleo-presence, distribution and thicknesses of past glaciers. We investigate the paleoenvironmental implications of three Mid to Late Pleistocene volcanic deposits in the Garibaldi volcanic belt of southwestern British Columbia, Canada. We use these data to inform a simple geometric model that constrains paleo-glacier distributions in the southern Canadian Cordillera. The three volcanoes are used to recover: i) a coalesced mountain ice sheet in late marine isotope stage (MIS) 4, and possibly into MIS 3 (up to ~49.1 ± 5.5 ka), ii) major and rapid degradation of glaciers during the late, MIS 6 to 5e transition (by 141 ± 12.9 ka ), and, iii) a coalesced mountain ice sheet, or continental ice sheet that existed during MIS 15 (598 ± 7.5 ka).