Determining the tectonic history of the basins and bathymetric highs of the South Scotia Ridge is essential to understand the paleo-current history of cold dense waters which escape the Weddell Sea and connect with the Atlantic Ocean, as well as understanding the pre-break up configuration of the South America - Antarctic Peninsula land bridge and how and when the South Scotia Ridge formed.
Determining the origin of these blocks requires direct sampling by dredging for petrological, geochemical and geochronological study. Discovery Bank was the prime target for dredge sampling followed by Bruce and Pirrie banks. Sampling of sediments deposited on the basement highs for biostratigraphic, petrological and geochemical/isotopic work also has the potential to record past changes in ocean circulation (Antarctic Circumpolar Current influence vs stronger Weddell Sea influence), productivity and sea-ice extent with emphasis on the most recent periods of glacial enhancement of the West Antarctic Ice Sheet and warm interglacials. This work would complement IODP Leg 382, scheduled for 2019, to drill sediments deposited in the basins bordered by Bruce and Pirie banks.
Geophysical surveys and direct sampling of sediments of the South Orkney Plateau (SOP) will investigate glacial landforms in troughs that were created by fast-flowing ice during the last glaciation (c. 20 000 years ago). For example, suites of small (<5 m high) moraines, which can only be identified by high-resolution 3D mapping of the seafloor and sub-surface sediments, indicate "episodic" retreat of grounded ice back towards the landmasses. By taking seafloor cores targeted to sample the transition between subglacial and postglacial sediments we can add a chronology of South Orkney ice cap retreat to the record provided by the glacial landforms; longer cores can be used to identify significant climatic/oceanographic changes that may have driven the retreat.
Teal R Riley (British Antarctic Survey)
British Antarctic Survey (BAS)
South West Atlantic Ocean (limit 20W) Southern Ocean
Scotia Sea, Atlantic sector of the Southern Ocean
Other physical oceanographic measurements
Quantity: activity duration in days = 12 Description: Sound velocity probe measurements
Geology and geophysics
Quantity: number of stations = 15 Description: Geological dredge sampling
Core - soft bottom
Quantity: number of stations = 32 Description: Gravity and box core sampling
Quantity: activity duration in days = 16 Description: EM122/710 swath bathymetry data
Quantity: activity duration in days = 16 Description: Gravimeter
Quantity: activity duration in days = 12 Description: Magnetometer deployment