Neogene Volcanism in the Transantarctic Mountains – an Overview of Recent Palaeoenvironmental Research

Giovedì 10 maggio alle ore 13.30, in Aula C presso il Dipartimento di Scienze della Terra, John Smellie (Department of Geology, University of Leicester, LE1 7RH, UK) terrà un seminario dal titolo: "Neogene Volcanism in the Transantarctic Mountains – an Overview of Recent Palaeoenvironmental Research"


Volcanism in the Transantarctic Mountains spans the period between c. 20 Ma and present and extends over a distance of 2000 km. It includes well-known active volcanoes at Mt Erebus and Mt Melbourne and is particularly widespread in northern Victoria Land, but it also includes the two most southerly volcanoes in the world just 300 km from South Pole. The volcanism has been the subject of much petrological research but its value for understanding past changes in environmental conditions has been largely undervalued. Yet it remains the sole record of the terrestrial environmental conditions for much of the Miocene and Pliocene. The volcanism is characterised by large long-lived (multi-million year) shield- and stratovolcanoes and by numerous small short-lived pyroclastic cones. The large centres have been a major target of several investigations, mainly since 2005 and principally supported by PNRA, with a central focus on uncovering and documenting evidence of past ice (i.e. glaciovolcanism). As a result, we now have considerable information on the glacial periods. For example, we know that ice thicknesses in northern Victoria Land were typically < 300 m and the ice simply draped the landscape rather than drowning it, but that was not always the case. Moreover, the basal thermal regime of that ice was polythermal and the ice did not evolve from wet-based to cold-based in a single step-change, as was predicted by the prevailing paradigm. Since 2014-15 however, volcanic investigations in the region have refocused on a search for evidence of the non-glacial periods, to see how the Mio-Pliocene climate affected the local landscape. No previous investigations had uncovered information on the non-glacial conditions. However, as a result of the recent studies, we now know that non-glacial conditions are indeed represented. The evidence is frequently not obvious and it can be difficult to interpret, which is why it was initially missed, but several outcrops provide unambiguous information on non-glacial conditions. That evidence will be reviewed in this talk for the first time.