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

In order to document changes in Holocene glacier extent and activity inNEGreenland (~73° N) we study marine sediment records that extend from the fjords (PS2631 andPS2640), across the shelf (PS2623 andPS2641), to the Greenland Sea (JM07‐174GC). 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 corePS2640 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 (SedUnMixMC) is used to characterize down‐core changes in sediment composition based on the upper late Holocene sediments from coresPS2640 (Sofia Sund),PS2631 (Kaiser Franz Joseph Fjord) andPS2623 (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 centredc. 2.5, 4.5 and 7.5 cal. kaBP(±0.5 ka) but are rarely linked with changes in the grain‐size spectra. CoarseIRD(>2 mm) andIRD‐grain‐size spectra are rare in the last 9–10 cal. kaBPand, in contrast with areas farther south (~68° N), there is no distinctIRDsignal 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.

 
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NSF-PAR ID:
10245740
Author(s) / Creator(s):
 ;  ;  ;  
Publisher / Repository:
Wiley-Blackwell
Date Published:
Journal Name:
Boreas
Volume:
45
Issue:
3
ISSN:
0300-9483
Page Range / eLocation ID:
p. 381-397
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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