A model for interaction between conduits and surrounding hydraulically connected distributed drainage based on geomorphological evidence from Keewatin, Canada

Abstract

Abstract. We identify and map visible traces of subglacial meltwater drainage around the former Keewatin Ice Divide, Canada, from high-resolution Arctic Digital Elevation Model (ArcticDEM) data. We find similarities in the characteristics and spatial locations of landforms traditionally treated separately (i.e. meltwater channels, meltwater tracks and eskers) and propose that creating an integrated map of meltwater routes captures a more holistic picture of the large-scale drainage in this area. We propose the grouping of meltwater channels and meltwater tracks under the term meltwater corridor and suggest that these features in the order of 10s–100s m wide, commonly surrounding eskers and transitioning along flow between different types, represent the interaction between a central conduit (the esker) and surrounding hydraulically connected distributed drainage system (the meltwater corridor). Our proposed model is based on contemporary observations and modelling which suggest that connections between conduits and the surrounding distributed drainage system within the ablation zone occur as a result of overpressurisation of the conduit. The widespread aerial coverage of meltwater corridors (5 %–36 % of the bed) provides constraints on the extent of basal uncoupling induced by basal water pressure fluctuations. Geomorphic work resulting from repeated connection to the surrounding hydraulically connected distributed drainage system suggests that basal sediment can be widely accessed and evacuated by meltwater.

Regional stagnation of the western Keewatin ice sheet and the significance of meltwater corridors and eskers, northern Canada

“…Eastward from the GSL cluster, and extending ~ 400 km to the Dubawnt Lake dated site (~ 5.55 ka) there are no dates to draw reliable isochrones across our study area. While dates ~400 km to the north (all marine dates, > 7.74 ka, with landforms), and, south of 60 degrees north, may allow for isochrone delineation, these examples indicate that the Keewatin chronology is not well constrained, certainly not to ~100 year isochrone resolution as applied by some (Lewington et al 2020b).…”

“…Deglaciation by 'rapid retreat' has been proposed for portions of the Canadian Arctic (Stokes et al 2008) including being invoked by Lewington et al (2020b) as part of stepwise retreat in western Keewatin. Rapid retreat (Clark et al 2000), or recession at rates > 50 m to ~300 m /year (e.g., Stokes et al 2008), may be a viable option for explaining the sparseness of ice-marginal landforms in western Keewatin.…”

A new map of glacigenic features and glacial landsystems in central mainland Nunavut, Canada

“…This compilation does not include minor or major meltwater channels; most of the previously mapped channels ( n = 15 873) would need to be re‐drawn along with new channels using ArcticDEM (Lewington et al . 2020).…”

“…Recent automatic detection and mapping methods using high‐resolution ArcticDEM data have also been developed to gain insight into their formation (Lewington et al . 2019, 2020).…”

Glacial geomorphology of the Kola Peninsula and Russian Lapland

“…Recent advances in our understanding of palaeo-ice sheet signatures and ice dynamics (e.g. Chandler et al, 2018;Chiverrell et al, 2020;Clark et al, 2018;Hughes et al, 2016;Lewington et al, 2020;McMartin et al, 2021;Peterson et al, 2017;Stokes et al, 2015;Stokes et al, 2016;Stroeven et al, 2016), coupled with the availability of new high-resolution digital elevation models (DEM) and satellite imagery, warrants a fresh investigation into Late Weichselian glaciation of northwest Arctic Russia. We present a new highresolution glacial geomorphological dataset of glacial landforms and sediments from the Kola Peninsula and Russian Lapland.…”