High-resolution Seismic Evidence for Multiple Glaciation across the Southwest Iceland Shelf

Abstract

Geophysical and lithological data collected from the southwest margin of Iceland provide clear evidence of multiple glaciations across the shelf, many of which reached the shelf-slope break. These paleo-ice sheets delivered much glacial sediment to the slope facing Denmark Strait. A large moraine some 20 to 100 m in height lies at the shelf break due west of Látra Bank. The moraine may mark the Late Weichselian extent of the western Iceland ice, although a single date from a 50-cm gravity core collected from the seaward side of the moraine provided an age of 35,650 ± 560 ¹⁴C BP. Retreat of this ice sheet appears to have been rapid, except for a minor pause when the ice sheet terminus approached the coastline. A marine reservoir-corrected basal date of 12,705 ± 85 ¹⁴C BP was obtained from a 17-m giant piston core collected in Jökuldjúp (a shelf trough) which sampled glacial marine sediments close to underlying ice-contact sediment. Because this date is very close to the age of shells near the marine limit in West Iceland, some 100 km to the east-northeast, it suggests that this margin of the Iceland Ice Sheet retreated extremely rapidly during the Bølling/Allerød interstadial (13,000 to 11,000 ¹⁴C BP).