Abstract Cenozoic magmatic rocks related to the West Antarctic Rift System crop out right across Antarctica, in Victoria Land, Marie Byrd Land and into Ellsworth Land. Northern Victoria Land, located at the northwestern tip of the western rift shoulder, is unique in hosting the longest record of the rift-related igneous activity: plutonic rocks and cogenetic dyke swarms cover the time span from c. 50 to 20 Ma, and volcanic rocks are recorded from 15 Ma to the present. The origin of the entire igneous suite is debated; nevertheless, the combination of geochemical and isotopic data with the regional tectonic history supports a model with no role for a mantle plume. Amagmatic extension during the Cretaceous generated an autometasomatized mantle source that, during Eocene–present activity, produced magma by small degrees of melting induced by the transtensional activity of translithospheric fault systems. The emplacement of Eocene–Oligocene plutons and dyke swarms was focused along these fault systems. Conversely, the location of the mid-Miocene–present volcanoes is governed by lithospheric necking along the Ross Sea coast for the largest volcanic edifices; while inland, smaller central volcanoes and scoria cones are related to the establishment of magma chambers in thicker crust.

Abstract Mount Melbourne and Mount Rittmann are quiescent, although potentially explosive, alkaline volcanoes located 100 km apart in Northern Victoria Land quite close to three stations (Mario Zucchelli Station, Gondwana and Jang Bogo). The earliest investigations on Mount Melbourne started at the end of the 1960s; Mount Rittmann was discovered during the 1988–89 Italian campaign and knowledge of it is more limited due to the extensive ice cover. The first geophysical observations at Mount Melbourne were set up in 1988 by the Italian National Antarctic Research Programme (PNRA), which has recently funded new volcanological, geochemical and geophysical investigations on both volcanoes. Mount Melbourne and Mount Rittmann are active, and are characterized by fumaroles that are fed by volcanic fluid; their seismicity shows typical volcano signals, such as long-period events and tremor. Slow deformative phases have been recognized in the Mount Melbourne summit area. Future implementation of monitoring systems would help to improve our knowledge and enable near-real-time data to be acquired in order to track the evolution of these volcanoes. This would prove extremely useful in volcanic risk mitigation, considering that both Mount Melbourne and Mount Rittmann are potentially capable of producing major explosive activity with a possible risk to large and distant communities.