Abstract
Abstract. A radiocarbon-dated marine sediment core retrieved in Kane Basin, central Nares Strait, was analysed to constrain the timing of the postglacial opening of this Arctic gateway and its Holocene evolution. This study is based on a set of sedimentological and geochemical proxies of changing sedimentary processes and sources that provide new insight into the evolution of ice sheet configuration in Nares Strait. Proglacial marine sedimentation at the core site initiated ca. 9.0 cal ka BP following the retreat of grounded ice. Varying contributions of sand and clasts suggest unstable sea ice conditions and glacial activity, which subsisted until ca. 7.5 cal ka BP under the combined influence of warm atmospheric temperatures and proglacial cooling induced by the nearby Innuitian (IIS) and Greenland (GIS) ice sheets. An interval rich in ice-rafted debris (IRD) is interpreted as the collapse of the ice saddle in Kennedy Channel ca. 8.3 cal ka BP that marks the complete opening of Nares Strait and the initial connection between the Lincoln Sea and northernmost Baffin Bay. Delivery of sediment by icebergs was strengthened between ca. 8.3 and ca. 7.5 cal ka BP following the collapse of the buttress of glacial ice in Kennedy Channel that triggered the acceleration of GIS and IIS fluxes toward Nares Strait. The destabilisation in glacial ice eventually led to the rapid retreat of the GIS in eastern Kane Basin at about 8.1 cal ka BP as evidenced by a noticeable change in sediment geochemistry in our core. The gradual decrease in carbonate inputs to Kane Basin between ∼8.1 and ∼4.1 cal ka BP reflects the late deglaciation of Washington Land. The shoaling of Kane Basin can be observed in our record by the increased winnowing of lighter particles as the glacio-isostatic rebound brought the seabed closer to subsurface currents. Reduced iceberg delivery from 7.5 to 1.9 cal ka BP inferred by our dataset may be linked to the retreat of the bordering ice sheets on land that decreased their number of marine termini.
Highlights
The Holocene history of Nares Strait, Northwest Greenland, has remained somewhat cryptic despite investigations during the past 4 decades (e.g. Blake Jr., 1979; Kelly and Bennike, 1992; Mudie et al, 2004; Jennings et al, 2011.)
The comparison of the 210Pb profiles of core AMD14-Kane2b and the box core collected at the same location reveals the relatively good recovery of the topmost sediments in the CASQ core permitted by the large diameter of this corer
∼ 9.0 cal ka BP or unit 3 ∼ 8.3 cal ka BP) in core AMD14Kane2b might represent the opening of Kennedy Channel
Summary
The Holocene history of Nares Strait, Northwest Greenland, has remained somewhat cryptic despite investigations during the past 4 decades (e.g. Blake Jr., 1979; Kelly and Bennike, 1992; Mudie et al, 2004; Jennings et al, 2011.). The Holocene history of Nares Strait, Northwest Greenland, has remained somewhat cryptic despite investigations during the past 4 decades Despite the importance of Nares Strait, intrinsic investigations into its late Pleistocene history, which is intimately linked with the dynamics of the bordering Innuitian (IIS) and Greenland (GIS) ice sheets, are relatively sparse and Published by Copernicus Publications on behalf of the European Geosciences Union. England, 1976), while others argued that the IIS coalesced with the bordering Greenland and Laurentide ice sheets (e.g. Blake Jr., 1970). Bennike et al, 1987; Blake Jr. et al, 1992; Kelly and Bennike, 1992) settled the argument in favour of the latter narrative by supporting the coalescence of the IIS and GIS along Nares Strait between 19 and ca. The presence of erratic boulders originating from Greenland on Ellesmere Island (England, 1999), cosmogenic nuclide surface-exposure dating (Zreda et al, 1999), and radiocarbon dating on mollusc shells (e.g. Bennike et al, 1987; Blake Jr. et al, 1992; Kelly and Bennike, 1992) settled the argument in favour of the latter narrative by supporting the coalescence of the IIS and GIS along Nares Strait between 19 and ca. 8 14C ka BP
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