Sea ice, ice‐rafting, and ocean climate across Denmark Strait during rapid deglaciation (∼16–12 cal ka BP) of the Iceland and East Greenland shelves

Andrews, John T.; Cabedo‐Sanz, Patricia; Jennings, Anne E.; Ólafsdóttir, Sædís; Belt, Simon T.; Geirsdóttir, Áslaug

doi:10.1002/jqs.3007

Cited by 23 publications

(14 citation statements)

References 149 publications

(247 reference statements)

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“…; Andrews et al . ), but tills also are commonly barren of dateable fossil material (Jennings ). The bulk density and shear strength of L1 were not measured, but the unit is noticeably compact, cracked and dense.…”

Section: Discussionmentioning

confidence: 99%

Retreat of the Smith Sound Ice Stream in the Early Holocene

Jennings

Andrews

Oliver

et al. 2019

Boreas

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Nares Strait, a major connection between the Arctic Ocean and Baffin Bay, was blocked by coalescent Innuitian and Greenland ice sheets during the last glaciation. This paper focuses on the events and processes leading to the opening of the strait and the environmental response to establishment of the Arctic‐Atlantic throughflow. The study is based on sedimentological, mineralogical and foraminiferal analyses of radiocarbon‐dated cores 2001LSSL‐0014PC and TC from northern Baffin Bay. Radiocarbon dates on benthic foraminifera were calibrated with ΔR = 220±20 years. Basal compact pebbly mud is interpreted as a subglacial deposit formed by glacial overriding of unconsolidated marine sediments. It is overlain by ice‐proximal (red/grey laminated, ice‐proximal glaciomarine unit barren of foraminifera and containing >2 mm clasts interpreted as ice‐rafted debris) to ice‐distal (calcareous, grey pebbly mud with foraminifera indicative of a stratified water column with chilled Atlantic Water fauna and species associated with perennial and then seasonal sea ice cover) glacial marine sediment units. The age model indicates ice retreat into Smith Sound as early as c. 11.7 and as late as c. 11.2 cal. ka BP followed by progressively more distal glaciomarine conditions as the ice margin retreated toward the Kennedy Channel. We hypothesize that a distinct IRD layer deposited between 9.3 and 9 (9.4–8.9 1σ) cal. ka BP marks the break‐up of ice in Kennedy Channel resulting in the opening of Nares Strait as an Arctic‐Atlantic throughflow. Overlying foraminiferal assemblages indicate enhanced marine productivity consistent with entry of nutrient‐rich Arctic Surface Water. A pronounced rise in agglutinated foraminifers and sand‐sized diatoms, and loss of detrital calcite characterize the uppermost bioturbated mud, which was deposited after 4.8 (3.67–5.55 1σ) cal. ka BP. The timing of the transition is poorly resolved as it coincides with the slow sedimentation rates that ensued after the ice margins retreated onto land.

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Section: Discussionmentioning

confidence: 99%

Retreat of the Smith Sound Ice Stream in the Early Holocene

Jennings

Andrews

Oliver

et al. 2019

Boreas

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“…This is well constrained by 10 Be dating in coastal areas and 14 C dated marine cores in and outside major transect troughs, and applies to areas in western, eastern and southernmost Greenland (Fig 4). More recently this has been corroborated by new evidence from the Disko Bugt shelf (Hogan et al, 2016;Oksman et al, 2017) , and from east Greenland (Levy et al, 2016;Andrews et al, 2018;Dyke et al, 2018;Rainsley et al, 2018). However, this has recently been contested by evidence from multibeam bathymetry in major transverse troughs on the shelf, notably the occurrence of Grounding Zone Wedges (GZWs) as discussed below.…”

Section: Yd Ice-margins In Greenlandmentioning

confidence: 82%

“…Mörner and Funder, 1990), acknowledging that significant, but unknown, changes in the reservoir effect may potentially/likely have affected the ages especially in the turbulent millennia during the early deglaciation phases (e.g. Andrews et al, 2018).…”

Section: Field and Laboratory Methodsmentioning

confidence: 99%

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Younger Dryas ice-margin retreat in Greenland, new evidence from Southwest Greenland

Funder¹,

Sørensen²,

Larsen³

et al. 2020

Preprint

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Abstract. Cosmogenic 10Be dates from bedrock knobs on six outlying tiny islands along a stretch of 300 km of the Southwest Greenland coast, indicate that the Greenland Ice Sheet (GrIS) margin here was retreating on the inner shelf close to the coast during the Younger Dryas (YD) cold period. A survey of recently published 10Be and 14C-dated records show that this unexpected behaviour of the ice-margin has been seen also in other parts of Greenland, but with very large variations in extent and speed of retreat even between neighbouring areas. In contrast to this, landforms appearing in high resolution bathymetry surveys on the shelf, have recently been suggested to indicate YD readvance or long-lasting ice-margin still stand on mid shelf, far from the coast. However, these features have been dated primarily by correlation with cold periods in the ice core temperature records, and therefore cannot inform about the ice-margin/climate relation. Ice-margin retreat during a YD cooling has been explained by advection of warm subsurface water melting the ice-margin, and by increased seasonality of the climate with the temperature drop mainly in winter, with high impact on sea ice extent and duration, but little effect on glacier mass balance. This study therefore adds to the complexity of the climate/ice-margin relation, where local factors may for some time overrule or mute overall temperature change. It also points to the urgent need for climate-independent dating of the rich treasure trove of information coming from the shelf in these years.

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“…Gray's map for April and May 1882 shows the ice encircling Iceland but, with Faxaflói ice free (Figure 1). Jennings, Andrews, and Wilson (2015) argued that icebergs from the Laurentide Ice Sheet reached southwest Iceland during the early Holocene and certainly the quartz wt% are also much higher in cores such as MD99-2256 and MD99-2259 immediately following deglaciation ( Figure 8D; Andrews et al 2018). Faunal and stable isotopic evidence in a push core (from box core HU93030-003; Jennings et al 2001) suggested colder ocean conditions during the Little Ice Age (LIA) and perhaps also indicating drift-ice transport into Faxaflói in the coastal current.…”

Section: Southwest Iceland Shelf: Faxaflóimentioning

confidence: 99%

Tracking Holocene drift-ice limits on the northwest–southwest Iceland shelf: Comparing proxy data with observation and historical evidence

Andrews

Jónsdóttir

Geirsdóttir

2019

Arctic, Antarctic, and Alpine Research

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We detail variations in the weight percent (wt%) of quartz, a proxy for drift ice, in fifteen marine sediment cores from the northwest, west, and southwest Iceland shelf throughout the past 10 cal ka BP. We present the first map of iceberg distributions in Iceland waters between 1983 and 2011 and a new compilation of sea-ice records in the century from 850 to 1950 CE. The wt% of quartz, determined by quantitative X-ray diffraction (qXRD) analysis, is used to evaluate changes in the importation of drift ice. Small wt% of quartz were added to milled basalt (0% quartz), and to a mixture of non-clay and clay minerals; the qXRD method replicated 0 percent quartz, while measured 1-3 percent quartz always resulted in a "presence" estimate. The outer sites in the northwest sector lie close to the average position of the sea-ice margin between 1870 and 1920 CE; the southwest shelf sites lie south of this limit. Transects of cores along the Húnaflói and Djúpáll troughs indicate that the traces of drift ice decrease rapidly landward from the outer sites. The cores from the west/southwest of Iceland have limited amounts of quartz, generally possibly limited incursions of drift ice.

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Sea ice, ice‐rafting, and ocean climate across Denmark Strait during rapid deglaciation (∼16–12 cal ka BP) of the Iceland and East Greenland shelves

Cited by 23 publications

References 149 publications

Retreat of the Smith Sound Ice Stream in the Early Holocene

Retreat of the Smith Sound Ice Stream in the Early Holocene

Younger Dryas ice-margin retreat in Greenland, new evidence from Southwest Greenland

Tracking Holocene drift-ice limits on the northwest–southwest Iceland shelf: Comparing proxy data with observation and historical evidence

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