From source to sink: Quantifying Quaternary erosion from offshore deposits associated with the Greenland Ice Sheet

Glacially derived, marine sediments preserve a record of the timing, extent, and dynamics of shelf glaciation. In addition, these deposits can provide constraints on glacial erosion rates and offer insights into landscape evolution. However, in Greenland, the total offshore volume of glacially derived sediments remains poorly constrained due to an uneven distribution of offshore seismic surveys and a lack of dating constraints. To address this, we present a first quantification of Quaternary glacial sediment thicknesses around Greenland, combining interpretations of available marine seismic data with age constraints where scientific boreholes are available and a neural network approach. We train the neural network using the seismic-derived thicknesses, along with several parameters related to glacial and geomorphological features. This approach allows us to predict Quaternary sediment thicknesses in regions with sparse data coverage, thereby constraining the total volumes of deposition. Our estimates reveal regional variations in glacial deposition volumes and sediment thicknesses around Greenland. On the southern and parts of the northern Greenlandic continental slope, Quaternary sediments are thin, whereas in west and east Greenland, larger sediment deposits have led to a greater shelf progradation throughout the Quaternary. These patterns demonstrate a diverse influence of (paleo-)climatic, oceanographic, and orographic processes on glacial dynamics and the source-to-sink sediment transport. Finally, we compare our estimates of Quaternary offshore deposition with estimates of onshore glacial erosion inferred from paleo-topographic reconstructions and erosion potentials of the present ice sheet, based on ice sliding velocities. This provides insights into the temporal and spatial variability of erosion around Greenland, advancing our understanding of the long-term landscape evolution in glaciated regions.