Chapter 4.1a Antarctic Peninsula: volcanology

Abstract

AbstractThe Antarctic Peninsula is distinguished by late Neogene volcanic activity related to a series of northerly younging ridge crest–trench collisions and the progressive opening of ‘slab windows’ in the subjacent mantle. The outcrops were amongst the last to be discovered in the region, with many occurrences not visited until the 1970s and 1980s. The volcanism consists of several monogenetic volcanic fields and small isolated centres. It is sodic alkaline to tholeiitic in composition, and ranges in age between 7.7 Ma and present. No eruptions have been observed (with the possible, but dubious, exception of Seal Nunataks in 1893) but very young isotopic ages for some outcrops suggest that future eruptions are a possibility. The eruptions were overwhelmingly glaciovolcanic and the outcrops have been a major source of information on glaciovolcano construction. They have also been highly influential in advancing our understanding of the configuration of the Plio-Pleistocene Antarctic Peninsula Ice Sheet. However, our knowledge is hindered by a paucity of modern, precise isotopic ages. In particular, there is no obvious relationship between the age of ridge crest–trench collisions and the timing of slab-window volcanism, a puzzle that may only be resolved by new dating.