Changes in Glacial-Marine Sedimentation in Core HU77-159, Frobisher Bay, Baffin Island, N.W.T: A Record of Proximal, Distal, and Ice-Rafting Glacial-Marine Environments

Abstract

Core HU77-159 from Frobisher Bay, Baffin Island, Canada records the sedimentologic and biologic conditions associated with three distinct glacial-marine sediment types that can be correlated to a 14C dated terrestrial glacial chronology. The chronology of events recorded at the core site is controlled by five 14C dates and by paleomagnetic studies. During the Hall glacial advance in Frobisher Bay at shortly before 10,760± yr B.P., proximal glacial-marine conditions are recorded in HU77-159. The proximal glacial-marine sediments consist of clay, rich in detrital carbonate and other clay-sized minerals, which suggest erosion of bedrock, a low rate of sand influx, but increased quartz grain angularity, and a characteristic low diversity Elphidium excavatum forma clavata foraminiferal assemblage. Distal glacial-marine sediments are found directly above and below the proximal sediments, and these record conditions prior to and after the Hall advance. Ice-distal glacialmarine sediments are typically silty clays, with moderate CaCO3 percentages, sand influx, and grain angularity. Bentnic foraminifera in ice-distal glacial-marine sediments, are more abundant and diverse than in the ice-proximal environment reflecting an improved environment. In the upper portion of HU77-159, ice-rafted glacial-marine sediments have been deposited since the removal of glacier ice from Frobisher Bay. Ice-rafted sediments are noticeably sandier than the lower units and contain maxima of sand influx and grain angularity. Benthic foraminifera in the ice-rafting environment are the most abundant and diverse assemblages in the last 12,000 yr. Marine sedimentological processes have been dominant in middle Frobisher Bay at depths of 500–600 m throughout the Holocene.