The retreat pattern of glaciers controls the occurrence of turbidity currents on high-latitude fjord deltas

Abstract

 Glacial erosion is necessary to provide the sediment supply required for turbidity 23 currents to be generated on delta fronts 24  Lakes formed during glacial retreat significantly alter sediment delivery, stopping 25 turbidity currents 26  Pattern of retreating glaciers dictates the non-linear nearshore hydrodynamics of fjords 27 This article is a non-reviewed preprint published at EarthArXiv Abstract 28 Glacier and ice sheet mass loss as a result of climate change is driving important coastal changes 29 in Arctic fjords. Yet, limited information exists for Arctic coasts regarding the influence of 30 glacial erosion and ice mass loss on the occurrence and character of turbidity currents in fjords 31 which themselves affect delta dynamics. Here, we show how glacial erosion and the production 32 of meltwaters and sediments associated with the melting of retreating glaciers control the 33 generation of turbidity currents in fjords of eastern Baffin Island (Canada). The subaqueous 34 parts of 31 river mouths were mapped by high-resolution swath bathymetry along eastern Baffin 35 Island in order to assess the presence or absence of sediment waves formed by turbidity currents 36 on delta fronts. By extracting glaciological and hydrological watershed characteristics of these 37 river mouths, we demonstrate that the presence and areal extent of glaciers is a key control for 38 generating turbidity currents in fjords. However, lakes formed upstream during glacial retreat 39 significantly alter the course of sediment routing to the deltas by forming temporary sinks, 40 leading to the cessation of turbidity currents in the fjords. Due to the different deglaciation 41 stages of watersheds in eastern Baffin Island, we put these results into a temporal framework 42 of watershed deglaciation to demonstrate how the retreat pattern of glaciers, through the 43 formation and filling of proglacial lakes, affects the activity of deltas.44

Retreat and stabilization of a marine-based ice margin along a high arctic fjord-cross-shelf trough system

“…Similar landforms were previously identified from several glaciated locations (Powell, 1990;Lønne, 1995;Dowdeswell and Vásquez, 2013;Normandeau et al, 2019;Lajeunesse, 2019a, 2019b). Parallel channels are more common on glacially-fed fans suggesting higher turbidity currents activity used for delivering sediments downslope (Dowdeswell and Vásquez, 2013;Batchelor et al, 2018;Normandeau et al, 2019). Transverse curvilinear ridges observed on foreset beds are crescent-shaped landforms formed by turbidity currents (Normandeau et al, 2019).…”

“…These fan-shaped landforms are interpreted as glaciofluvial fans formed by sediment delivery by glacial meltwaters from adjacent alpine valleys (Powell, 1990;Normandeau et al, 2019). Similar landforms were previously identified from several glaciated locations (Powell, 1990;Lønne, 1995;Dowdeswell and Vásquez, 2013;Normandeau et al, 2019;Lajeunesse, 2019a, 2019b).…”

“…These fan-shaped landforms are interpreted as glaciofluvial fans formed by sediment delivery by glacial meltwaters from adjacent alpine valleys (Powell, 1990;Normandeau et al, 2019). Similar landforms were previously identified from several glaciated locations (Powell, 1990;Lønne, 1995;Dowdeswell and Vásquez, 2013;Normandeau et al, 2019;Lajeunesse, 2019a, 2019b). Parallel channels are more common on glacially-fed fans suggesting higher turbidity currents activity used for delivering sediments downslope (Dowdeswell and Vásquez, 2013;Batchelor et al, 2018;Normandeau et al, 2019).…”

“…Parallel channels are more common on glacially-fed fans suggesting higher turbidity currents activity used for delivering sediments downslope (Dowdeswell and Vásquez, 2013;Batchelor et al, 2018;Normandeau et al, 2019). Transverse curvilinear ridges observed on foreset beds are crescent-shaped landforms formed by turbidity currents (Normandeau et al, 2019).…”