Distinct modes of meltwater drainage and landform development beneath the last Barents Sea ice sheet

Frontiers in Earth Science

Earth Science

Mariana Esteves¹  Monica Winsborrow¹  Karin Andreassen¹  Henry Patton¹  Lilja Bjarnadóttir²  Calvin Shackleton³ 

[1] CAGE—Centre for Arctic Gas Hydrate, Environment and Climate, Department of Geosciences, UiT the Arctic University of Norway, Tromsø, Norway;Geological Survey of Norway (NGU), Trondheim, Norway;Norwegian Polar Institute, Tromsø, Norway;CAGE—Centre for Arctic Gas Hydrate, Environment and Climate, Department of Geosciences, UiT the Arctic University of Norway, Tromsø, Norway;

关键词: esker;    subglacial drainage;    ice sheet hydrology;    glacial geomorphology;    barents sea;    tunnel valley;    meltwater channel;    beaded esker;   

DOI  :  10.3389/feart.2023.1111396

 received in 2022-11-29, accepted in 2023-04-03,  发布年份 2023

来源: Frontiers

【 摘 要 】

The flow of glacial ice is impacted by basal meltwater drainage systems that fluctuate on a continuum from distributed, high-pressure environments to channelized, lower pressure networks. Understanding the long-term development of dominant drainage modes and impacts on ice flow and landform development is a crucial step in predicting palaeo and contemporary ice-mass response to changes in climate. The spatial and temporal scales at which different drainage modes operate are largely unknown, and the geomorphological legacy of subglacial meltwater networks that evolve over a glaciation provide composite records of drainage system development. Here, we use high-resolution bathymetric data from shallow banks in the central Barents Sea to map the geomorphological imprint of meltwater drainage beneath the collapsing marine-based Barents Sea Ice Sheet (BSIS). We observe a succession of distinct meltwater landforms that provide relative timing constraints for subglacial drainage modes, indicating that extensive networks of channelized drainage were in operation during deglaciation. Interlinked basins and channels suggest that meltwater availability and drainage system development was influenced by filling and draining cycles in subglacial lakes. Networks of eskers also indicate near-margin meltwater conduits incised into basal ice during late-stage deglaciation, and we suggest that these systems were supplemented by increased inputs from supraglacial melting. The abundance of meltwater during the late stages of BSIS deglaciation likely contributed to elevated erosion of the sedimentary substrate and the mobilisation of subglacial sediments, providing a sediment source for the relatively abundant eskers found deposited across bank areas. A newly discovered beaded esker system over 67 km long in Hopendjupet constrains a fluctuating, but generally decelerating, pace of ice retreat from ∼1,600 m a−1 to ∼620 m a−1 over central Barents Sea bank areas during a 91-year timespan.

【 授权许可】

Unknown   
Copyright © 2023 Shackleton, Patton, Winsborrow, Esteves, Bjarnadóttir and Andreassen.