The Quaternary Lancaster Sound trough‐mouth fan, NW Baffin Bay

Abstract

The development of the Lancaster Sound Trough Mouth Fan (TMF) and glacial history in Arctic Canada were studied using a high-resolution seismic profile across the entire fan and two piston cores. Stacked tills separated by erosion surfaces on the shelf pass seaward through till deltas into thick transparent glacigenic debris flow (GDF) deposits on the slope, separated by thin, wellstratified glaciomarine layers. An age model was built by ties to the Ocean Drilling Program Site 645. The deepest GDF on the seismic profile was indicative of the onset of shelf-crossing glaciation in the Early Pleistocene. The transition of the growth of Lancaster Sound TMF from an aggradational sequence (unit M) to an aggradational-progradational sequence (unit F) occurred at the Middle Pleistocene transition in glacial cyclicity. In the most recent glacial cycle, GDF sheets were deposited during Heinrich events 4 and 2 according to the correlation of the main detrital carbonate beds in two piston cores. The outmost till wedge reflects the maximum advance of the grounding glacier, far seaward of previously proposed Last Glacial Maximum ice extent.

Ice streams in the Laurentide Ice Sheet: Identification, characteristics and comparison to modern ice sheets

“…2; England et al, 2006;Shaw et al, 2006;De Angelis and Kleman, 2007;Rashid and Piper, 2007;Todd et al, 2007;Li et al, 2011;Batchelor et al, 2013aBatchelor et al, ,b, 2014Jakobsson et al, 2014). However, major uncertainties exist with regard to the existence and extent of ice shelves that could have exerted a buttressing effect and protected the ice stream termini from calving.…”

“…In their updated inventory, Margold et al (2015) also used the International Bathymetric Chart of the Arctic Ocean (IBCAO: Jakobsson et al, 2000) and more detailed swath bathymetry data from the Canadian Arctic (ArcticNet, 2013) to identify several new ice streams and confirm others that were previously hypothesised based only on terrestrial evidence. These bathymetric data have also been complemented by sub-surface data obtained from seismic reflection surveys, allowing workers to identify multiple till units, grounding zone wedges and other glacial features buried in the marine sediments; and to investigate the architecture of large trough mouth fans that often lie distal to the major ice stream troughs (Jennings, 1993;Andrews et al, 1995b;Rashid and Piper, 2007;Li et al, 2011;Siegel et al, 2012;Batchelor et al, 2013a,b;.…”

“…2, 3;Sugden, 1977;De Angelis and Kleman, 2005;Briner et al, 2006;Simon et al, 2014), which is evidenced by a major sediment bulge protruding into Baffin Bay (Li et al, 2011;. The divide between the M'Clure Strait and Amundsen Gulf Ice Stream catchments and the Lancaster Sound Ice Stream catchment was probably highly mobile, and there is evidence for ice piracy whereby Keewatin ice was captured from the onset zone of the M'Clure Strait (later M'Clintock Channel) Ice Stream across the Boothia Peninsula and southern Somerset Island into the Lancaster Sound Ice Stream catchment (Figs.…”

“…2). Indeed, the LGM ice margin has recently been re-drawn to the edge of the continental shelf in most areas (Shaw et al, 2006;Li et al, 2011;Lakeman and England, 2013;Jakobsson et al, 2014), but the timing of ice streaming remains uncertain, especially in terms of when they might have switched on in these settings: before, during or immediately after the LGM? Very little is known about pre-LGM ice streaming within the LIS.…”

The Greenland Ice Sheet during the last glacial cycle: Current ice loss and contribution to sea-level rise from a palaeoclimatic perspective

“…Andrews et al, 1998;Simon et al, 2014). These detrital carbonate layers are interpreted to reflect incursions of Atlantic water (Hiscott et al, 1989) to the margins of the large Laurentide-and Innuitian ice streams that terminated at the northern shores of Baffin Bay (Li et al, 2011). It is thought that incursions of Atlantic water so far north would also affect the margins of the West Greenland ice streams, as was demonstrably the situation after the LGM .…”