Late Quaternary glacial and sedimentary history of Bonavista Bay, northeast Newfoundland

Abstract

High-resolution seismic profiles and core data from Bonavista Bay, northeast Newfoundland, show that the sedimentary package above acoustic basement was deposited during the deglaciation of the Late Wisconsinan ice sheet. During the Late Wisconsinan maximum (~ 20 000 BP), Bonavista Bay was occupied by a grounded ice sheet that extended farther offshore. Deglaciation of the bay was rapid and occurred prior to ~ 13 500 BP during a time of rising sea level. A basal till was deposited beneath the grounded ice, and after lift-off an ice shelf developed over the outer basins where diamicton was deposited. The inner bay gradually deglaciated as the ice margin retreated to the present-day shoreline by ~ 13 000 BP, and fine-grained outwash sediments transported by interflows were rapidly deposited. The inner bay remained under the influence of one or more remnant ice centres until ~ 10 000 BP, with ice positioned on the Bonavista and Gander peninsulas. Normal marine conditions were established in the outer bay by ~ 13 500 BP and in the inner bay and fjords by ~ 10 000 BP.