Late Quaternary changes in sediment composition on the NE Greenland margin (~73° N) with a focus on the fjords and shelf

• Published in: Boreas
• Main Authors: Andrews, John T., Stein, Rüdiger, Moros, Matthias, Perner, Kerstin
• Other Authors: National Science Foundation, Deutsche Forschungsgemeinschaft
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2016
• Subjects: Arctic; Kara Sea; Greenland; Sund; Sofia Sund; glacier; Greenland Sea; Shannon
• Online Access: http://dx.doi.org/10.1111/bor.12169; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fbor.12169; https://onlinelibrary.wiley.com/doi/pdf/10.1111/bor.12169; https://onlinelibrary.wiley.com/doi/full-xml/10.1111/bor.12169; https://onlinelibrary.wiley.com/doi/am-pdf/10.1111/bor.12169

In order to document changes in Holocene glacier extent and activity in NE Greenland (~73° N) we study marine sediment records that extend from the fjords ( PS 2631 and PS 2640), across the shelf ( PS 2623 and PS 2641), to the Greenland Sea ( JM 07‐174 GC ). The primary bedrock geology of the source areas is the Caledonian sediment outcrop, including Devonian red beds, plus early Neoproterozoic gneisses and early Tertiary volcanics. We examine the variations in colour ( CIE *), grain size, and bulk mineralogy (from X‐ray diffraction of the <2 mm sediment fraction). Fjord core PS 2640 in Sofia Sund, with a marked red hue, is distinct in grain size, colour and mineralogy from the other fjord and shelf cores. Five distinct grain‐size modes are distinguished of which only one is associated with a coarse ice‐rafting signal – this mode is rare in the mid‐ and late Holocene. A sediment unmixing program (SedUnMix MC ) is used to characterize down‐core changes in sediment composition based on the upper late Holocene sediments from cores PS 2640 (Sofia Sund), PS 2631 (Kaiser Franz Joseph Fjord) and PS 2623 (south of Shannon Is), and surface samples from the Kara Sea (as an indicator of transport from the Russian Arctic shelves). Major changes in mineral composition are noted in all cores with possible coeval shifts centred c . 2.5, 4.5 and 7.5 cal. ka BP (±0.5 ka) but are rarely linked with changes in the grain‐size spectra. Coarse IRD (>2 mm) and IRD ‐grain‐size spectra are rare in the last 9–10 cal. ka BP and, in contrast with areas farther south (~68° N), there is no distinct IRD signal at the onset of neoglaciation. Our paper demonstrates the importance of the quantitative analysis of sediment properties in clarifying source to sink changes in glacial marine environments.