Seafloor geomorphology of western Antarctic Peninsula bays: a signature of ice flow behaviour

Abstract

Abstract. Glacial geomorphology is used in Antarctica to reconstruct ice advance during the Last Glacial Maximum and subsequent retreat across the continental shelf. Analogous geomorphic assemblages are found in glaciated fjords and are used to interpret the glacial history and glacial dynamics in those areas. In addition, understanding the distribution of submarine landforms in bays and the local controls exerted on ice flow can help improve numerical models by providing constraints through these drainage areas. We present multibeam swath bathymetry from several bays in the South Shetland Islands and the western Antarctic Peninsula. The submarine landforms are described and interpreted in detail. A schematic model was developed showing the features found in the bays: from glacial lineations and moraines in the inner bay to grounding zone wedges and drumlinoid features in the middle bay and streamlined features and meltwater channels in the outer bay areas. In addition, we analysed local variables in the bays and observed the following: (1) the number of landforms found in the bays scales to the size of the bay, but the geometry of the bays dictates the types of features that form; specifically, we observe a correlation between the bay width and the number of transverse features present in the bays. (2) The smaller seafloor features are present only in the smaller glacial systems, indicating that short-lived atmospheric and oceanographic fluctuations, responsible for the formation of these landforms, are only recorded in these smaller systems. (3) Meltwater channels are abundant on the seafloor, but some are subglacial, carved in bedrock, and some are modern erosional features, carved on soft sediment. Lastly, based on geomorphological evidence, we propose the features found in some of the proximal bay areas were formed during a recent glacial advance, likely the Little Ice Age.

Insights into glacial processes from micromorphology of silt-sized sediment

“…Thus, this finding suggests that most grains in our study underwent some degree of subglacial transport and a subsequent increase in measurable roundness and regularity beneath fast-flowing ice. Such ice-streaming conditions have similarly been inferred from other paleo-subglacial records, such as subglacial bedforms and till properties, in the studied regions (Nitsche et al, 2013;Esteves et al, 2017;Jakobsson et al, 2018;Munoz and Wellner, 2018;Simkins et al, 2018;Kirkham et al, 2019Kirkham et al, , 2020. However, no geomorphic evidence of ice streaming exists on Thor Iversenbanken (Esteves et al, 2022).…”

Topographic Controls on Channelized Meltwater in the Subglacial Environment

“…Deglaciated terrains are particularly useful in mapping subglacial drainage pathways that leave an imprint on the bed in the form of infilled Röthlisberger (R) channels (i.e., eskers) incised upward into basal ice and bed-incised Nye (N) channels (Greenwood et al, 2016;Kehew et al, 2012;and references therein). Many examples of meltwater landforms are found in regions formerly covered by glacial systems that experienced significant ice-surface melting, whereas there have been fewer definitive landforms observed in Antarctica (Greenwood et al, 2012;Munoz & Wellner, 2018;Simkins et al, 2017). We describe a relict subglacial meltwater corridor, marking spatially expansive channelized drainage on the Antarctic Ross Sea continental shelf in Pennell Trough (Figure S1 in Supporting Information S1; partially reported by Wellner et al, 2006).…”

Ocean warming drives rapid dynamic activation of marine-terminating glacier on the west Antarctic Peninsula

“…We extracted sea floor topography in the Hugo-Anvers Trough and Cadman Glacier fjord using direct bathymetric measurements from British Antarctic Survey vessels and data from the International Bathymetric Chart of the Southern Ocean (IBCSO v2) 95 , 96 , supplemented by a previous study which mapped the geomorphology of Beascochea Bay from data collected in 2007 90 .…”