Chronological constraints on Cordilleran Ice Sheet glaciomarine sedimentation from core MD02-2496 off Vancouver Island (western Canada)

Abstract

Chronology based on 46 radiocarbon dates has been generated for MD02-2496, western Vancouver Island, Canada. Subsequent correlation between glaciomarine sedimentary sequences within the core and the terrestrial stratigraphy of the Cordilleran Ice Sheet for the last 50 ka provide new insight into Cordilleran Ice Sheet processes. Glaciomarine sedimentation associated with the most recent advance (Fraser Glaciation) of the Cordilleran Ice Sheet began at 30.5 cal kyr BP (∼25 14C kyr BP). Extremely high sedimentation rates indicate the ice sheet became proximal to the site at ∼19.5 cal kyr BP (16 14C kyr BP). Deposition of ice rafted detritus (IRD) began at ∼17 cal kyr BP (14 14C kyr BP), and abruptly terminated at ∼16.2 cal kyr BP (13.5 14C kyr BP) indicating rapid regional ice sheet retreat. A minor IRD event followed at ∼14.7 cal kyr BP (12.5 14C kyr BP). Glaciomarine sediment deposition abruptly ended at 10.2 cal kyr BP (∼8.8 14C kyr BP) with the resumption of biogenic sedimentation. The Olympia Interstade is represented by an interval of hemipelagic sedimentation between ∼43 and 31.5 ka. Prior to ∼45 ka sediment deposition is controlled by glaciomarine processes with evidence for a significant IRD event at ∼47 cal kyr BP (>41±1.06 14C kyr BP).