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238-5 Subglacial erosion rates calculated from proglacial sediments in two marine terminating glaciers in West Greenland

Session: Recent Advances and New Voices in Marine and Coastal Geoscience

Presenting Author:

Jonathan Amendola

Authors:

Amendola, Jonathan P.¹, Sherman, Dallas², Gulick, Sean S.³, Goff, John A.⁴, Jaeger, John M.⁵, Durr, Rachael⁶

(1) University of Texas at Austin, Jackson School of Geosciences, Austin, TX, USA, (2) University of Texas at Austin, Jackson School of Geosciences, Austin, TX, USA, (3) University of Texas at Austin, Jackson School of Geosciences, Austin, TX, USA, (4) University of Texas at Austin, Jackson School of Geosciences, Austin, TX, USA, (5) University of Florida, Gainesville, FL, USA, (6) University of Florida, Gainesville, FL, USA,

Abstract:

Marine terminating glaciers deliver an enormous quantity of sediment to the global ocean, but interactions between glaciers and the sediment they create and export remain understudied. As part of the TERMINUS project to investigate causes of tidewater glacier stability, we conducted a geophysical and sedimentological survey of two glacier termini, Kangerlussuup Sermia (KAS) and Kangerluarsuup Sermia (KSS), located in central west Greenland. KAS has remained relatively stable over several decades, whereas KSS has retreated >1.5 km from its 1980s position. We hypothesize that the different volumes of sediment eroded by these systems may be responsible for their divergent behavior. The July-August 2024 research cruise, conducted aboard the R/V Celtic Explorer, utilized shipboard chirp seismic and multibeam bathymetry systems, in addition to a high resolution multichannel seismic reflection (MCS) system with a GI gun source and 350 m streamer length featuring denser near channel spacing. Using the chirp and MCS reflection data, we identified seismic facies that we interpret to represent paleomoraines, ice-proximal, ice-distal, and periglacial sediment deposits that allow for reconstructions of past termini positions. We find in both systems a prominent moraine assumed to be formed during the Little Ice Age (LIA) outboard of an overdeepened basin. In KAS, MCS and chirp data reveal an outer basin infilled with complex sediment packages recording retreat and advance facies overtopped by an extensive submarine drainage system feeding a substantial submarine delta. In KSS, the LIA to 1980s retreat facies are relatively limited, and sedimentation since the 1980s is limited to low amplitude cyclic steps on top of the partially exposed morainal complex. We use the internal structure of the submarine delta deposits to determine areal extent, formation processes, and relative age. Using these data, we derive post-LIA sediment volumes and use these to estimate preliminary basin-scale erosion rates for both systems. We intend to use these basin sediment volumes to establish post-LIA sedimentation and erosion rates for KAS and KSS to better understand the factors that drive subglacial erosion and proglacial sedimentation.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-8956

Subglacial erosion rates calculated from proglacial sediments in two marine terminating glaciers in West Greenland

Description

Session Format: Oral

Presentation Date: 10/22/2025

Presentation Start Time: 09:15 AM

Presentation Room: HBGCC, 213AB

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