The role of meltwater in high-latitude trough-mouth fan development: The Disko Trough-Mouth Fan, West Greenland

Abstract

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Quantifying Provenance and Transport Pathways of Holocene Sediments From the Northwestern Greenland Margin

“…From ~8.5 to 7.5 cal ka BP, the sedimentation changed to a laminated unit. As suggested in a previous study (Caron, St‐Onge, et al, 2019), these laminations could indicate more unstable conditions (successions of rapidly deposited layers from turbidity currents) during this period, but still related to the deposition of sediments suspended in turbid meltwater plumes (e.g., Jenner et al, ; Ó Cofaigh et al, ; Sheldon et al, ). This layer reflects relatively greater distance from the ice margin (compared to Unit 1) but likely still associated to high meltwater discharges from GIS (Moros et al, ; Seidenkrantz et al, ) and an extended sea‐ice cover (e.g., Caron, Rochon, et al, 2019).…”

“…The base of core 210 (prior to ~9.5 cal ka BP) is characterized by a coarse‐grained and poorly sorted deposit corresponding to ice‐marginal glaciomarine conditions, and a relatively fast rate of deposition was assumed for this layer (Caron, St‐Onge, et al, 2019). This deposit is likely associated to the remobilization of subglacial till or glaciogenic sediments, transported by debris flow (e.g., Ó Cofaigh, Dowdeswell, et al, 2013, ). The sediment composition for this unit appears to be fluctuating from a mix of different sources from the West Greenland (mainly WGMC#3 but with significant contribution of WGMC#4), as reflected by the SedUnMixMC results and by quartz/clays, K/Al, and Fe/Al ratios (Figure ).…”

“…During the Last Glacial Maximum (LGM), the GIS was ~65% more enlarged than present (Funder et al, ) and extended to the continental shelf edge (e.g., Ó Cofaigh, Dowdeswell, et al, 2013). Consequently, the expansive West Greenland shelf (WGS) is marked by large troughs extending seaward up to the continental slope, and trough‐mouth fans are observed along the shelf break (e.g., Aksu & Piper, ; Batchelor & Dowdeswell, ; Ó Cofaigh, Dowdeswell, et al, 2013, ; Jakobsson et al, ). Because of their potential for rapid sediment accumulation, these cross‐shelf troughs are excellent locations to study paleoenvironmental changes at a high temporal resolution (multicentury), as they can record past glacial (and deglacial) conditions (e.g., Dowdeswell et al, ; Jennings et al, ).…”

Meltwater sediment transport as the dominating process in mid-latitude trough mouth fan formation

“…T rough mouth fans are products of repeated glacigenic sediment delivery from former fast-flowing outlets of ice sheets, and act as high-resolution paleoclimate and icesheet monitors [1][2][3] . The fans have highest sedimentation rates and maximum periods of growth during glacial maxima, whereas they become ice-distal glacimarine environments with low sedimentation rates during interglacials 4 .…”

“…1b). Large-volume meltwater delivery forms hyperpycnal flows, which result in the deposition of turbiditic sequences 2,[18][19][20][21] . Turbidites detected on glacial fans are thus used as a proxy for meltwater delivery 13,22 .…”