The geomorphometry of Antarctic submarine canyons

Abstract

Submarine canyons are deep, large-scale incisions found on most of the world's continental margins. In Antarctica, canyons are widespread features driving mesoscale oceanographic processes with significant implications for global climate and circulation, connecting shallow to deep sedimentary processes and positively influencing biodiversity and ecosystem functioning. The understanding of their oceanographic, climatic, geological and ecological significance is limited by the detail, accuracy and extent of canyon inventory. This study aims to create the best possible catalogue of Antarctic submarine canyons and gullies taking advantage of the new International Bathymetric Chart of the Southern Ocean (IBSCO) v.2. Semi-automatic hydrological techniques were adopted to delineate the drainage network, and to extract attributes such as the stream order, stream gradient and sinuosity. We identified 332 drainage networks with 3291 stream segments, nearly 5 times the number of canyons identified in previous studies, and calculated 15 morphometric parameters for each segment. We observe significant differences across Antarctic margins. East Antarctica shows the most complex and largest drainage networks, while the Antarctic Peninsula has the greatest number of networks, although with the lowest stream orders and shortest lengths. Western Antarctica has less complexity and shorter network lengths compared to East Antarctica. These differences may reflect the contrasting glacial histories of the two regions, with the earlier onset of the East Antarctic Ice Sheet leading to older and more developed canyon systems.