Weichselian–Holocene glacial history of the Sjuøyane archipelago, northern Svalbard

Abstract

The Sjuøyane archipelago is the northernmost land area of Svalbard; thus, it provides a window to study the terrestrial glacial history and dynamics of the Svalbard–Barents Sea Ice Sheet and complement marine geological studies in the region. To reconstruct the glacial history of Sjuøyane, we describe coastal sedimentary sections in Quaternary sediments and constrain their chronology by radiocarbon and optically stimulated luminescence ages. Erratic boulders and bedrock are sampled for ¹⁰Be cosmogenic exposure dating, aiming to determine the deglaciation age and exposure history. Holocene environments are studied based on lake sediments and emerging vegetation from retreating snow patches. The sedimentary sections largely consist of shallow (glacio-)marine and/or littoral sediments deposited during high relative sea levels. The radiocarbon and luminescence ages suggest they formed during a Middle Weichselian interstadial, and after the Late Weichselian glaciation. A wave-washed bedrock erosional notch and rounded boulders at 36±1 m a.h.t. most likely formed during this interstadial. Most of the cosmogenic ¹⁰Be ages are older than the last deglaciation, likely indicating a complex exposure history. One boulder sample suggests that the lowlands were deglaciated 14.7±1.82 ka ago, and two boulder samples with ages of 18.94±3.26 and 22.89±4.05 ka suggest that the highlands were possibly ice-free at this time. The lake sediments from Isvatnet, Phippsøya, consist of glaciolacustrine silt and clay overlain by gyttja. The gyttja has accumulated at least since 7.0 cal. ka BP. Two radiocarbon ages from emerging vegetation suggest Neoglacial cooling since 3.8 cal. ka BP. A patchy glacial drift at the surface of Sjuøyane and well-preserved pre-Late Weichselian sediments suggest that the Late Weichselian glaciation was non-erosive and/or cold-based at this part of the north margin of the Svalbard–Barents Sea Ice Sheet.