Abstract Since Jurassic time ( c. 200 Ma), Antarctica has had a greater diversity of volcanism than other southern continents. It includes: (1) voluminous mafic and felsic volcanism associated with the break-up of Gondwana; (2) a long-lived continental margin volcanic arc, including back-arc alkaline volcanism linked to slab rollback; (3) small-volume mafic alkaline volcanism associated with slab-window formation; and (4) one of Earth's major continental rift zones, the West Antarctic Rift System (WARS), with its numerous large alkaline central volcanoes. Several of Antarctica's volcanoes are still active. This chapter is a review of the major volcanic episodes and their principal characteristics, in their tectonic, volcanological and palaeoenvironmental contexts. Jurassic Gondwana break-up was associated with large-scale volcanism that caused global environmental changes and associated mass extinctions. The volcanic arc was a major extensional arc characterized by alternating volcanic flare-ups and lulls. The Neogene rift-related alkaline volcanism is dominated by effusive glaciovolcanic eruptions, overwhelmingly as both pāhoehoe- and ‘a‘ā-sourced lava-fed deltas. The rift is conspicuously poor in pyroclastic rocks due to the advection and removal of tephra erupted during glacial intervals. Volcanological investigations of the Neogene volcanism have also significantly increased our knowledge of the critical parameters and development of the Antarctic Ice Sheet.

Abstract On the basis of 2D multichannel and very-high-resolution seismic data and swath bathymetry, we report a sequence of giant mass-transport deposits (MTDs) in the Scan Basin (southern Scotia Sea, Antarctica). MTDs with a maximum thickness of c. 300 m extend up to 50 km from the Discovery and Bruce banks towards the Scan Basin. The headwall area consists of multiple U-shaped scars intercalated between volcanic edifices, up to 250 m high and 7 km wide, extending c. 14 km downslope from 1750 to 2900 m water depth. Seismic sections show that these giant MTDs are triggered by the intersection between diagenetic fronts related to silica transformation and vertical fluid-flow pipes linked to magmatic sills emplaced within the sedimentary sequence of the Scan Basin. This work supports that the diagenetic alteration of siliceous sediments is a possible cause of slope instability along world continental margins where bottom-simulating reflectors related to silica diagenesis are present at a regional scale.

Abstract The behaviour of ice caps and glaciers on sub-Antarctic islands during previous periods of warming provide key empirical evidence for understanding the behaviour of marine ice sheets in the future. However, the extent of ice on sub-Antarctic islands during the last 100 kyr is poorly constrained. Here, we investigate the past glacial extents on South Georgia, where previous Last Glacial Maximum (LGM) reconstructions vary between small fjord-terminating glaciers and a large marine-based ice sheet. To help resolve this uncertainty, we apply Schmidt hammer relative-age dating to measure rock hardness and, thus, exposure age of a range of glacial deposits. Applying a hardness–age calibration curve constructed from well-dated Holocene, late-glacial deposits and terminal LGM deposits, we determine that deglaciation of the approximately 600 m-high peaks on the outer Lewin Peninsula occurred during the latter half of the last glacial stage, and probably the end of the LGM. We infer that South Georgia was covered by a marine-based ice cap during the latter part of the last glacial stage.