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

Abstract

The mineralogical and geochemical compositions of three sediment cores from the northwestern Greenland continental margin (AMD14-204 and AMD14-210) and Kane Basin (AMD14-Kane2B) were investigated using quantitative X-ray diffraction and energy-dispersive X-ray fluorescence in order to document the impact of ice-ocean interactions on the sediment provenance and transport pathways during the Holocene. Unmixing of the sediment composition and ratios such as quartz/clays and K/Fe indicate that detrital sediments in cores from the northwest Greenland margin are derived mainly from Prøven granite and reworked Archean gneiss, whereas sediments from Kane Basin are derived mainly from detrital carbonate (Ellesmere Island) and Proterozoic gneiss (Humboldt Glacier). Mineralogical and geochemical signatures also reveal that changes in detrital sediment provenance and transport in the region are strongly interconnected to regional ice stream dynamics, especially during the early Holocene with strong meltwater discharge from the Greenland Ice Sheet associated with the end of deglaciation. With the establishment of milder conditions during the mid-Holocene and reduced glacial activity once ice sheets retreated inland, sediment inputs via ocean currents became more effective. Thus, detrital proxies in core AMD14-204, located in the Upernavik cross-shelf trough, support the hypothesis of an intensification of the West Greenland Current influence after 7.7 cal ka BP, which eventually affected the regional sediment dynamic by a greater contribution from basalt to the sediment supply. Finally, our results suggest that the interactions between climate, glacial dynamics, and surface ocean circulation controlled the paleoenvironmental changes observed in the three cores.

Learning from the past: Impact of the Arctic Oscillation on sea ice and marine productivity off northwest Greenland over the last 9,000 years

“…The proxy signal suggests enhanced surface‐water cooling and freshening during this interval, likely partly associated with increased meltwater input. This is supported by the observed increase in IRD between 2.3 and 2 kyr BP at our study site (Caron et al., 2020), and is coherent with the retreat of the Qangattaq ice cap on the Nuussuaq peninsula between c. 2.5 and 1.9 kyr BP (Schweinsberg et al., 2017) and the Greenland ice‐sheet margin in Northern Nunatarssuaq between 2.1 and 1.6 kyr BP (Farnsworth et al., 2018), at the transition to a period of significant boreal atmospheric warming that is commonly referred to as the Roman Warm Period (~2.0–1.65 kyr BP, Wanner et al., 2008). Biomarker and foraminiferal datasets further suggest the potential complete collapse of the Kane Basin ice arch in Nares Strait during this interval (Georgiadis et al., 2020), which would have further promoted the export of freshwater and (multiyear) ice into northern Baffin Bay.…”

“…From 7.7 kyr BP, a steep increase in the sedimentary TOC contents indicates either a transition to a more productive system and/or reduced detrital input from meltwater. This TOC flux increase is coeval with a WGC strengthening inferred from the mineralogical and elemental composition of the sedimentary material (Caron, Montero‐Serrano, St‐Onge, & Rochon, 2020), and enhanced abundance of foraminiferal species indicative of Atlantic Water influx at our study site (Hansen et al., 2020; Figure 6). From c. 7 kyr BP, a progressive strengthening of the WGC has also been recorded in Disko Bay (e.g., Ouellet‐Bernier, de Vernal, Hillaire‐Marcel, & Moros, 2014; Perner, Moros, Jennings, Lloyd, & Knudsen, 2012) and attributed to the onset of deepwater formation in the Labrador Sea (Hillaire‐Marcel & Vernal, 2008), presumably linked to a basin‐wide reorganization of the surface circulation in the northern Atlantic following the final retreat of the Laurentide and Greenland ice sheets (Dyke & Prest, 1987; Van Nieuwenhove, Baumann, Matthiessen, Bonnet, & de Vernal, 2016; Van Nieuwenhove et al., 2018).…”

“…This could partly explain the presence of sub-ice colonial species such as M. arctica that have developed strategies to mitigate the effect of unfavorable sea-ice microstructure (Krembs et al, 2011). To the north, evidence of instabilities in the Kane Basin ice arch (Georgiadis et al, 2020) at our study site (Caron et al, 2020), and is coherent with the retreat of the Qangattaq ice cap on the Nuussuaq peninsula between c. 2.5 and 1.9 kyr BP (Schweinsberg et al, 2017) and the Greenland ice-sheet margin in Northern Nunatarssuaq between 2.1 and 1.6 kyr BP (Farnsworth et al, 2018), at the transition to a period of significant boreal atmospheric warming that is commonly referred to as the Roman Warm Period (~2.0-1.65 kyr BP, Wanner et al, 2008).…”

Glacial history of Inglefield Land, north Greenland from combined in-situ <sup>10</sup>Be and <sup>14</sup>C exposure dating

“…In northwest Greenland, the period with restricted ice extent in Melville Bay c. 9.1 to 0.4 cal. ka BP, was driven by a strengthening of the West Greenland Current and warm ocean waters arriving in middle Holocene (Levac et al, 2001;Caron et al, 2020) (Fig. 9d).…”

Glacial history of Inglefield Land, north Greenland from combined in situ <sup>10</sup>Be and <sup>14</sup>C exposure dating

“…A particular challenge arises when subglacial bedrock erosion is too slow to remove 10 Be inventories produced during earlier exposure periods, such as the previous interglacial. In such cases, the resulting age is typically referred to as an apparent 10 Be exposure age in acknowledgement of the fact that this age typically exceeds the true exposure age (Kelly et al, 2008;Corbett et al, 2015;Farnsworth et al, 2018;Larsen et al, 2018;Søndergaard et al, 2019;Ceperley et al, 2020;Skov et al, 2020). This problem of 10 Be nuclide inheritance emphasizes the need for new methods to be implemented in order to thoroughly constrain the glacial history in parts of Greenland where the ice is coldbased and inefficient erosion leads to widespread nuclide inheritance.…”