Evolution of sea‐surface conditions on the northwestern Greenland margin during the Holocene

Abstract

Reconstructions of sea‐surface conditions during the Holocene were achieved on two sediment cores from the northwest Greenland margin (AMD14‐204) and Kane Basin (AMD14‐Kane2B) based on dinoflagellate cyst assemblages. On the northwest Greenland margin, sea‐surface conditions were cold with an extended sea ice cover prior to 7750 cal a bp associated with the end of the deglaciation. A major change occurred around ca. 7750 cal a bp with enhanced influence of warmer water from the West Greenland Current, and optimal sea‐surface conditions were observed around 6000 cal a bp. After 3350 cal a bp, results reflect the establishment of the modern assemblages. In the Kane Basin, sea‐surface conditions were not favourable for dinocyst productivity prior to 7880 cal a bp, as the basin was still largely covered by ice. The presence of warmer water is recorded between 7880 and 7200 cal a bp and the highest primary productivity between 5200 and 2100 cal a bp, but sea‐surface conditions remained cold with an extended sea ice cover throughout the Holocene. Overall, the results from this study revealed the strong influence of meltwater discharges and oceanic current variability on the sea‐surface conditions. Copyright © 2019 John Wiley & Sons, Ltd.

Quantifying Provenance and Transport Pathways of Holocene Sediments From the Northwestern Greenland Margin

“…In this context, our detrital proxies support the idea of a fast flowing Upernavik ice stream until ~7.7 cal ka BP, associated with a strong meltwater discharge from GIS (e.g., Moros et al, ), which brought fine detrital sediment (likely through meltwater plume as the dominant transport process) directly from the fjord to the core site (Figure ). Comparable results were also reported by Caron, St‐Onge, et al (2019) and Caron, Rochon, et al (2019) on the same sediment core 204, as reflected by the high abundance of cold‐water taxa associated with cold sea‐surface conditions, caused by meltwater input (Figure c). This hypothesis is also strongly supported by the previous results of Seidenkrantz et al () suggesting a widespread early Holocene meltwater discharge from GIS, which started prior to 8.6 cal ka BP and ended at ~7.7–7.5 cal ka BP.…”

“…Greenland Ice Sheet (GIS) minimum extent interval from Young and Briner (). The light blue shaded areas indicate the cold pulses observed in Caron, Rochon, et al (2019), and the green shaded areas highlight periods of important change discussed in this study.…”

“…The multiproxy approach presented here uses a combination of new mineralogical and geochemical records, associated to grain size and surface water proxies from the same set of samples (Caron, St‐Onge, et al, 2019 and Caron, Rochon, et al, 2019) in order to investigate palaeoceanographic changes along the northwestern Greenland margin. Overall, for the three cores, many major elements present good correlations with various minerals identified (Figure S4).…”

“…Comparison of (a) δ 18 O from Camp century (Vinther et al, 2009), (b) relative sea level reconstruction for the Melville Bay (approximatively, based on Fleming & Lambeck, 2004), (c) dinocyst cold water taxa (%) from Caron, Rochon, et al (2019), proportions of sediment from (d) Upernavik‐Charnokite and (e) basalts (WGMC#2, wt.%) for core 204, (f) amounts of very coarse silts (%) for core 204 (Caron, St‐Onge, et al, 2019), (g) freshwater indicator ( Halodinium ) influx from Caron, Rochon, et al (2019), (h) proportion of sediment from WGMC#3 (wt.%) for core 210, (i) amounts of fine and medium silts (%), and (j) sorting (mm) for core 210. Greenland Ice Sheet (GIS) minimum extent interval from Young and Briner ().…”

“…These results are used here to assess the contributions from specific sediment sources, evaluate the transport processes of detrital sediment, and provide new insights on potential relations between Holocene climatic variability, oceanic circulation variations, and sediment dynamics along the northwestern Greenland margin. A comparison with previously published sedimentological and palynological data from the same cores (Caron, St‐Onge, et al, 2019; Caron, Rochon, et al, 2019; Georgiadis et al, ) permitted to acquire a large overview of the paleoenvironmental changes occurring in these regions during the Holocene. Thus, our study differs from earlier publications with this multiproxy approach, which provides an opportunity to improve the regional knowledge of the environmental changes of the northwestern Greenland margin and Nares Strait during the Holocene.…”