Linking the terrestrial environmental record at Mason Spur volcanic complex with the middle Miocene−Pleistocene Ross Sea marine record, Antarctica: A history of subaerial (ice-free) eruptions and glaciovolcanism under variable ice thicknesses

Research into volcanism in southern Victoria Land, Antarctica, within the West Antarctic rift system, has focussed historically on the geochemistry and chronology of its volcanic centers. However, volcanoes in the West Antarctic rift system have also been dramatically influenced by the prevailing eruptive environment. Mason Spur is a middle Miocene to Pleistocene volcanic complex in the Erebus Volcanic Province. The deep interior of the complex is revealed and is used to assess its development under different environmental conditions. Many of the volcanic sequences erupted within ice and are thus ultraproximal compared with marine sediments, which are the usual source of environmental information. The volcanic rocks provide a unique, well-dated record of the terrestrial environmental conditions independent of the marine record, to which they are an important counterbalance. Evidence is provided for conditions varying between ice-free, alpine ice, and regional ice sheets, and direct comparisons are made with the marine record. The first contemporary ice thicknesses are also deduced for the Erebus Volcanic Province. The results significantly advance our understanding of the middle Miocene−Pleistocene Antarctic environment in the coastal Victoria Land region.