Eruptive history of Mason Spur, a Miocene—Pleistocene polygenetic volcanic complex in southern Victoria Land, West Antarctic Rift System, Antarctica

Abstract Mason Spur is a deeply eroded Middle Miocene to Pleistocene (c. 13 0.37 Ma) volcanic complex in southern Victoria Land, within the West Antarctic Rift System (WARS). The oldest rocks include large volume of trachyte ignimbrites that provided abundant detritus recovered McMurdo Sound drill cores. together with early-formed intrusions were strongly deformed during substantial caldera collapse at c. Ma. Intense erosion modified landscape, creating paleo-relief several hundred metres. Deep ravines cut and filled by deposits multiple lahars probably linked gravitational collapses dome(s). Small-volume trachytic magmas also erupted, forming lavas least one tuff cone. youngest activity comprises lava dome related block-and-ash-flow deposits, erupted 6 Basanite throughout history eruptions younger than 12 Ma are almost exclusively basanite, scoria cones, water-cooled lavas, cones. Three peripheral outcrops composed basanitic ‘a‘ā lava-fed deltas, from vents on neighbouring volcanoes Mount Discovery Morning. Abundant ignimbrite differentiate this others WARS. Eruptions triggered rift extension initially, yielding voluminous trachytes sourced magma chamber margin Later mafic associated deep crustal faults residual intraplate deformation. These results add important details eruptive intracontinental