Ice sheet dynamics on the Lofoten–Vesterålen shelf, north Norway, from Late MIS-3 to Heinrich Stadial 1

Abstract

We present an account of the glacial dynamics from late Marine Isotope Stage (MIS) 3 to the Heinrich Stadial (HS) 1 on the Lofoten–Vesterålen margin, Northern Norway. This account is based on an analysis of the sedimentary stratigraphy on the upper slope close to the ice sheet grounding line at the continental shelf edge, and an analysis of the glacial morphology on the shelf areas. Our results point to a dynamic ice sheet that waxed and waned on the Lofoten–Vesterålen continental shelf from the late MIS-3, through the Last Glacial Maximum (LGM) and the HS 1. Glacigenic debris flows and deposition of laminated diamicts suggest that the ice sheet reached the shelf edge on several occasions. These are dated to ∼25.5 ka BP (HS3), between 21.1 and 21.7 ka BP, ∼19.5 ka BP, 15.6 ka BP and 14.4 ka BP (uncorrected 14C ages). A contouritic sorted sand sediment unit that formed in a relatively warm interval during Late MIS-3 suggests that a strong Norwegian Atlantic Slope Current also developed during glacial interstadials implying that the oceanic circulation in the eastern Norwegian Sea was similar as today. The general pattern is that the ice sheet advanced onto the shelf during cold period with little influx of Atlantic Water to the Norwegian Sea and that it retreated toward the coast during intervals with higher temperatures and higher influx of warm Atlantic Water. The last ice advance to the edge of the continental shelf occurred during HS 1.