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Over the past decades, significant efforts have been made to understand the nature, dynamics and evolution of volcanic systems. In parallel, the continuous demographic expansion and extensive urbanization of volcanic areas have increased the exposure of our society to these natural phenomena. This increases the need to improve our capacities to accurately assess projected volcanic hazards and their potential socioeconomic and environmental impact, and Antarctica and the sub-Antarctic islands are no exception. More than a hundred volcanoes have been identified in Antarctica, some of which are entirely buried beneath the ice sheet and others as submarine volcanoes. Of these, at least eight large (basal diameters > c. 20-30 km) volcanoes are known to be active and pose a considerable threat to scientific and ever-increasing tourism activities being carried out in the region. Despite the scientific and socioeconomic interest, many aspects of the past volcanic activity and magmatic processes in Antarctica, and current volcanic hazards and risks, remain unknown. Moreover, many of Antarctica's volcanoes preserve a remarkable history of the eruptive environment, from which multiple parameters of past configurations of the Antarctic ice sheet (AIS) can be deduced. Given the critical role that the AIS plays in regulating Earth's climate, Antarctica's volcanoes therefore can be regarded as the ground truth for current models of past climates derived from modelling and studies of marine sediments. Here, we provide a succinct overview of the evolution of volcanism and magmatism in Antarctica and the sub-Antarctic region over the past 200 million years. Then, we briefly review the current state of knowledge of the most crucial aspects regarding Antarctica's volcanic and magmatic processes, and the contributions volcanic studies have made to our understanding of ice sheet history and evolution, geothermal heat flow, as well as present-day and future volcanic hazard and risk. A pri

Antarctica has undergone several important phases of volcanism throughout its long history. It was formerly at the heart of Gondwana but, from early Jurassic time (c. 200 Ma), it commenced the prolonged process of disintegration, which resulted in the dispersal and final disposition of the southern hemisphere continents that we are familiar with today (Veevers 2012; Storey and Granot 2021). As a consequence, volcanism has been particularly important in its construction and it is geographically widespread, although mainly located within West Antarctica (Fig. 1). Its effects have frequently been felt far outside of the continent. For example, it has been a driver of global mass extinctions (Burgess et al. 2015; Ernst and Youbi 2017) and it has potentially driven Antarctica climatically, and by implication the world, both into and out of glacials (Bay et al. 2006; McConnell et al. 2017). Conversely, Antarctica's volcanoes may have played a pivotal role in helping Life not only to survive multiple glacial episodes during the past few tens of millions of years but to undergo species diversification on the continent in spite of the dramatic climate variations (Fraser et al. 2014). Eruptions from Mount Erebus also represent a significant point source of gases and aerosols to the Austral polar troposphere, including affecting the ozone layer (Boichu et al. 2011; Zuev et al. 2015). Some of Antarctica's active volcanoes also have the potential to have a significant impact on southern hemisphere aviation (Geyer et al. 2017). Finally, Antarctica contains the world's largest and longest-lived glaciovolcanic province. The glaciovolcanic sequences contain a detailed record of the terrestrial Antarctic ice sheet going back to nearly 30 Ma and that record is now beginning to be tapped (e.g. Smellie et al. 2009; Smellie and Edwards 2016; Wilch et al. 2021). Despite these attributes, however, volcanism in Antarctica remains terra incognita to many Earth scientists, probably in large p

The 1.5 Ma evolution of the Late Pliocene (5.7 to 4.2 Ma) Mt Sidley volcano, Marie Byrd Land, is examined using major and trace elements, Sr, Nd, O and Pb isotopic data. A large (5 km × 5 km) breached caldera exposes lavas and tephras, deep within Mt Sidley, and allows its magmatic evolution to be elucidated. Two alkaline rock series are distinguished: (a) a strongly silica-under-saturated basanite to phonolite series; (b) a more silica-saturated to -oversaturated alkali basalt to trachyte series. Rock compositions in both series fall within a narrow range of 77Sr/86Sri (0.7028–0.7032), 143Nd/144Ndi (0.51285–0.51290) and δ18O (5.0–6.0‰), and with 206Pb/204Pb (>19.5), suggest an asthenospheric source containing a strong mantle plume component. Partial melting models require ≤2% melting to produce primary basanite and ≤5% melting to produce alkali basalt from the same mantle source. The differentiation of the phonolitic series is modeled by fractionation of diopside, olivine, plagioclase, titaniferous magnetite, nepheline and/or apatite from basanite to derive 35% mugearite, 25% benmoreite and 20% phonolite as residual liquids. Fractional crystallization of a similar mineral assemblage from alkali basalt is modeled for compositions in the trachyte series. However, many trachytes have variable 87Sr/86Sri (0.7033–0.7042), low 143Nd/144Ndi (0.51280–0.51283), high δ18O (6.5–8.4‰) and are silica oversaturated, suggesting they are contaminated by crust. The trachytes evolved by a two-step assimilation–fractional crystallization process (AFC). The first step involved contamination of alkali basalt by calc-alkaline granitoids within the middle crust where high assimilation to crystallization rates (high-r AFC) produced trachytic magmas characterized by depletions in Ta and Nb relative to K and Rb. The second step involved further fractionation of these magmas by low-r AFC within the upper crust to produce another suite of trachytes showing extreme incompatible element enrichm