|Title||Glacigenic debris-flows and down-slope gullies: evidence of a grounded ice margin during past glacials, South Shetland Trench, Antarctica|
|Download||Download (whole publication) |
|Author||Stewart, H A; Jamieson, A J; Ó Cofaigh, C; Bradwell, T|
|Source||Program and abstracts: 2017 GeoHab Conference, Dartmouth, Nova Scotia, Canada; by Todd, B J; Brown, C J; Lacharité, M; Gazzola, V; McCormack, E; Geological Survey of Canada, Open File 8295, 2017 p. 111,
https://doi.org/10.4095/305931 (Open Access)|
|Publisher||Natural Resources Canada|
|Meeting||2017 GeoHab: Marine Geological and Biological Habitat Mapping; Dartmouth, NS; CA; May 1-4, 2017|
|Related||This publication is contained in Todd, B J; Brown, C J;
Lacharité, M; Gazzola, V; McCormack, E; (2017). Program and abstracts: 2017 GeoHab Conference, Dartmouth, Nova Scotia, Canada, Geological Survey of Canada, Open File 8295|
|Area||Antarctica; Antarctic Peninsula; South Shetland Islands; Bransfield Strait; Drakes Passage; King George Island; Antarctica|
|Lat/Long WENS|| -63.0000 -54.0000 -61.0000 -63.0000|
|Subjects||marine geology; surficial geology/geomorphology; environmental geology; geophysics; tectonics; mapping techniques; oceanography; marine environments; continental margins; continental shelf; continental
slope; bathymetry; submarine features; ocean trenches; cold regions research; core samples; geophysical surveys; acoustic surveys, marine; sonar surveys; side-scan sonar; gullies; glaciology; glaciers; glacial erosion; ice margins; glacial deposits;
glaciomarine deposits; debris flows; debris flow deposits; glacial history; ice margins; tectonic setting; plate margins; subduction zones; structural features; faults; erosion; turbidity currents; South Shetland Trench; geological mapping;
geological mapping techniques; digital elevation models; high latitude mapping|
|Program||Ocean Management Geoscience, Offshore Geoscience|
|Released||2017 09 26|
|Abstract||The South Shetland Trench (SST) is located near the Antarctic Peninsula, around 100 km northwest, and parallel to, the South Shetland Islands. Although a number of studies examining glacial history have
been undertaken in the Bransfield Strait located between the South Shetland Islands and the Antarctic Peninsula to the south, the authors believe this is the first study of the seafloor glacial geomorphology, and recent glacial history of the SST.
This paper presents initial results from a EUROFLEETS Expedition to the SST that took place in December 2015. |
The Expedition collected three gravity cores, 3148 square kilometres of multibeam echosounder data and around 600 line kilometres of
Topas sub-bottom data covering part of the southern flank and trench floor of the study area. Additional bathymetry data derived from the Global Multi-Resolution Topography (GMRT) Synthesis (Marine Geoscience Data System www.marine-geo.org)
comprising a multi-resolution global Digital Elevation Model (DEM) that includes processed multibeam bathymetry data (100 m resolution) where available and gridded seafloor depths (30 arc-second resolution) derived from the General Bathymetric Chart
of the Oceans (GEBCO www.gebco.net). These combined data reveal the study area, north of King George Island, on the southern flank of the SST to host a system of linear downslope gullies, glacigenic debris flows and glacigenic deposits.
the study area glacigenic debris flows are found to extend from the continental shelf break to the lower continental slope. Sub-bottom profiler data penetrated up to 150 ms below seafloor in places and reveal a stacked sequence of debris flows
suggestive of a fluctuating ice front that was grounded to, and retreated from, the shelf break on several occasions.
More than eleven individual gullies (and their tributaries) were imaged between 450 m and 3600 m water depth. The gullies are
incised up to 250 m below the surrounding sea bed with internal slope angles locally exceeding 45° and were influenced by shallow transform faulting related to subduction processes.
Downslope gullies have been observed on other glaciated margins
such as the Scotian slope offshore Canada, Ross Sea Antarctica, north-western Barents Sea and West Shetland Margin offshore north-western UK. The gullies are inferred as being eroded by turbidity currents comprising cold, dense, sediment-rich
meltwater released from an ice front located at or near the continental shelf break.