Widespread, multi-source glacial erosion on the Chukchi margin, Arctic Ocean

Abstract

Abstractsuggests stepwise deglacial retreat towards the shelf, backing up the broad bathymetric trough at 20 the eastern side of the Rise. Glacigenic features other than extensive iceberg scouring cannot be 21 identified above 350-m depth, and no glacigenic bedforms are present on the current-swept shallow 22shelf. Despite the resulting uncertainty with the southern extent of the glaciation, the data suggest a 23 widespread grounded-ice presence on the northern Chukchi Shelf, which makes it an important, 24 previously underestimated component of the Arctic paleo-glacial system. 25

Differences between the last two glacial maxima and implications for ice-sheet, δ18O, and sea-level reconstructions

“…The input of ice-rafted debris (IRD) allows reconstruction of ice sheet dynamics, ice source, and iceberg-melt location (Ruddiman, 1977;Bond and Lotti, 1995;Hemming, 2004). The marine record of Eurasian glacial episodes (e.g., Spielhagen et al, 2004;Sejrup et al, 2005;Toucanne et al, 2009;Obrochta et al, 2014;L€ owemark et al, 2016) and geophysical mapping (e.g., Polyak et al, 2001Polyak et al, , 2004Jakobsson et al, 2010;Niessen et al, 2013;Dove et al, 2014), indicate differences between the LGM and PGM glaciations, with suggestions that the PGM/MIS 6 glaciation was one of the more extensive glacial episodes. Conversely, IRD from North America (Hudson Strait) does not seem to have reached the North Atlantic IRD belt during the penultimate glacial cycle (Obrochta et al, 2014), while it still occurred in the Labrador Sea, in close proximity to the eastern North American margin (Channell et al, 2012).…”

“…Recent geophysical mapping in the Arctic, however, has led to a re-evaluation of large floating Arctic ice shelves during the Pleistocene. Various mechanisms have been proposed to account for the mapped submarine features, including the drifting of ice-shelf remnants or mega-bergs trapped in multi-year sea ice, or a transient surge or brief grounding of a floating ice shelf (Polyak et al, 2001(Polyak et al, , 2009Engels et al, 2008;Dowdeswell et al, 2010;O'Regan et al, 2010;Gebhardt et al, 2011;Niessen et al, 2013;Dove et al, 2014). Age control for many of the features remains enigmatic, often relying on stratigraphic correlation and biostratigraphy; for example, identification of diagnostic MIS 5e nannofossils gives a likely, or minimum, MIS 6 age estimate for features on Morris Jesup Rise, Lomonosov Ridge, Yermak Plateau, Hovgaard Ridge, Mendeleev Ridge, and Arlis Plateau (Jakobsson, 1999;Polyak et al, 2001;Matthiessen and Knies, 2001;Kristoffersen et al, 2004;Spielhagen et al, 2004;Jakobsson et al, 2008Jakobsson et al, , 2010Jakobsson et al, , 2016Arndt et al, 2014;L€ owemark et al, 2016).…”

On the reconstruction of palaeo-ice sheets: Recent advances and future challenges

“…Similar scour marks and, in places, glacial bedforms such as flutings and megascale glacial lineations have also been used to invoke the presence of extensive and thick ice sheets and ice shelves along the Chukchi Borderland (Jakobsson et al, 2005;Dove et al, 2014) and southern Mendeleev Ridge (Niessen et al, 2013), which require revisions of glacial Arctic ice cover . More localised ice shelves have also been hypothesised, often in association with ice streams (e.g.…”

Submarine glacial landform distribution in the central Arctic Ocean shelf–slope–basin system

“…Ottesen et al 2007;Hogan et al 2010;Andreassen et al 2014;. Notably, such morainic ridges also exist in the East Siberian and Chuckhi seas on the continental slope in water depths even greater than 500 m, away from crossshelf troughs and the shallow continental-shelf margin (Niessen et al 2013;Dove et al 2014; (Fig. 2a).…”

“…Deep-drafted icebergs calved from the ice streams and drifted in the central Arctic Ocean before exiting through Fram Strait. Dated iceberg ploughmarks occur on bathymetric highs, extending into the central Arctic Ocean from the continental shelves, and on crests of ridges in the deep central basin (Jakobsson 1999;Polyak et al 2001;Jakobsson et al 2008;Dove et al 2014). Furthermore, mapping of glacial landforms and sediment coring provide evidence for a c. 1 km thick ice shelf that may have covered the entire central Arctic Ocean during the peak of the Marine Isotope Stage 6 (MIS 6) glacial period c. 140 ka ago .…”