A new bathymetric compilation for the South Orkney Islands region, Antarctic Peninsula (49°–39°W to 64°–59°S): Insights into the glacial development of the continental shelf

Abstract

We present a new, high resolution (300 m) bathymetric grid of the continental shelf surrounding the South Orkney Islands, northeast of the Antarctic Peninsula. The new grid, derived from a compilation of marine echo‐sounding data, improves previous regional bathymetric representations and helps to visualize the morphology of the shelf in unrivalled detail. The compilation forms important baseline information for a range of scientific applications and end users including oceanographers, glacial modelers, biologists, and geologists. In particular, due to the limited understanding of glacial history in this region, the bathymetry provides the first detailed insights into past glacial regimes. The continental shelf is dominated by seven glacially eroded troughs, marking the pathways of glacial outlets that once drained a former ice cap centered on the South Orkney Islands. During previous glacial periods, grounded ice extended to the shelf edge north of the islands. A large, ∼250 km long sediment depocenter, interpreted as a maximum former ice limit of one or more Cenozoic glaciations, suggests that ice was only grounded to the ∼300–350 m contour in the south. Hypsometric analyses support this interpretation, indicating that a significant proportion of the shelf has been unaffected by glacial erosion. Using these observations, we propose a preliminary ice cap reconstruction for maximum glaciation of the South Orkney plateau, suggesting an ice coverage of about ∼19,000 km2. The timing of maximum ice extent, number of past advances and pattern of subsequent deglaciation(s) remain uncertain and will require further targeted marine geological and geophysical investigations to resolve.

Major advance of South Georgia glaciers during the Antarctic Cold Reversal following extensive sub-Antarctic glaciation

“…8). The ice cap that expanded across the South Georgia shelf at the LGM is comparable to the expansion of the northern Antarctic Peninsula Ice Sheet70 and South Orkney Ice Cap71 which were both significantly advanced up to ∼19 cal ka B.P 617…”

Tectonic activity evolution of the Scotia‐Antarctic Plate boundary from mass transport deposit analysis

“…The evolution of the Scotia Sea created transpressive and transtensive segments leading to active and passive margins between oceanic basins and continental highs [ Barker et al ., ; Eagles et al ., ; Maldonado et al ., ; Dalziel et al ., ; Eagles and Jokat , ]. In addition, the proximity of the Scotia Sea to the Antarctic ice sheet [e.g., Dickens et al ., ] provides an interesting scenario for the study of the MTDs development under the influence of an oscillating ice cap. The action of vigorous bottom currents in the same region [ Orsi et al ., ; Naveira Garabato et al ., ], moreover, influences the distribution of deposits and complicates any evolutionary reconstruction [ Maldonado et al ., ].…”

An Antarctic krill (Euphausia superba) hotspot: population characteristics, abundance and vertical structure explored from a krill fishing vessel

“…The area is characterized by a steep slope from the shelf break to abyssal depths of around 3-4000 m, parallel to the east-west axis of the Coronation Island (South Orkneys largest island). There are two north-south-oriented canyons or troughs along this axis, the Monroe and Coronation Troughs (Dickens et al 2014). These areas are likely important for retention of krill advected along the shelf and slope region from areas further west and south-west, or via deeper currents from the Weddell Sea region flowing east and turning north in a counter clockwise fashion around the South Orkney plateau (cf.…”

“…The fishing vessels along track positions were coupled to the elevation data from the new bathymetric high-resolution grid (300 m) of the continental shelf surrounding the South Orkney Islands, northeast of the Antarctic Peninsula (Dickens et al 2014). The original data were downloaded from the Marine Geoscience Data System (MGDS) as a gridded file in GEOTIFF format.…”