17:15 〜 18:45
[MIS10-P11] Unveiled focused submarine troughs in front of Totten Glacier
キーワード：南極大陸棚、トッテン氷河、海底構造
In order to enhance our understanding of the continental shelf with the strong ice-ocean-crust interactions, we conducted a Japanese icebreaker’s bathymetric survey in front of the Totten glacier, East Antarctica, where ice-shelves are currently melting through basal contact with the warm water inflow (Hirano et al., 2023). We succeeded in the multibeam echo-sounding in front of Totten Glacier in March 2023. The ice shelf has melted and discharged offshore, and the seafloor topography of the previously ice-covered area was revealed this time. Multibeam bathymetric data were acquired using a 20 kHz SeaBeam3020 system (L3 Communications ELAC Nautik) installed on the icebreaker Shirase. The sound velocity was corrected by in-situ observational data of the of conductivity, temperature, and depth profiles.
New bathymetric data unveiled a submarine trough that continues beneath the ice shelf with narrow channels and branches. This result suggests that basal melting of ice shelves driven by warm water inflow occurs locally with a narrow width along the seafloor. The ice shelf fractures observed in the satellite images are consistent with the distribution of narrow submarine troughs, and also suggest the existence of submarine valleys that continue downstream of the ice shelf. This observation also suggests that the inflow of warm water induced by the topography is a major contributor to the mechanism that breaks up the ice into a lattice pattern. Further evaluation of ocean heat transport with in-situ and high-resolution data is essentially needed to understand factors that control the basal melt rate of Totten Ice Shelves.
Unveiled troughs have an overall northeast-southwest strike and were probably created by glacial erosion during the growth and retreat of the ice sheet, but the initial trigger is thought to be a structural boundary in the crust. The multiple orientations of the furrows also suggest that ablation by a single iceberg overrides the topography. In addition to the characteristics of the geologic basement, a complex history of ice sheet movement may have influenced trough formation. Further geophysical and geological investigation is essentially needed to understand the genesis of this Totten Glacier system including crustal component.
New bathymetric data unveiled a submarine trough that continues beneath the ice shelf with narrow channels and branches. This result suggests that basal melting of ice shelves driven by warm water inflow occurs locally with a narrow width along the seafloor. The ice shelf fractures observed in the satellite images are consistent with the distribution of narrow submarine troughs, and also suggest the existence of submarine valleys that continue downstream of the ice shelf. This observation also suggests that the inflow of warm water induced by the topography is a major contributor to the mechanism that breaks up the ice into a lattice pattern. Further evaluation of ocean heat transport with in-situ and high-resolution data is essentially needed to understand factors that control the basal melt rate of Totten Ice Shelves.
Unveiled troughs have an overall northeast-southwest strike and were probably created by glacial erosion during the growth and retreat of the ice sheet, but the initial trigger is thought to be a structural boundary in the crust. The multiple orientations of the furrows also suggest that ablation by a single iceberg overrides the topography. In addition to the characteristics of the geologic basement, a complex history of ice sheet movement may have influenced trough formation. Further geophysical and geological investigation is essentially needed to understand the genesis of this Totten Glacier system including crustal component.