Pyroclastic passage zones in glaciovolcanic sequences

• Published in: Nature communications Vol. 4; no. 1; p. 1788
• Main Authors: Russell, James K., Edwards, Benjamin R., Porritt, Lucy A.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 2013; Nature Publishing Group
• Subjects: 704/2151/209; 704/2151/431; 704/2151/598; Earth science; Humanities and Social Sciences; Ice sheets; Lava; multidisciplinary; Science; Science (multidisciplinary); Volcanoes; Volcanology; British Columbia Canada; Canada
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms2829

Volcanoes are increasingly recognized as agents and recorders of global climate variability, although deciphering the linkages between planetary climate and volcanism is still in its infancy. The growth and emergence of subaqueous volcanoes produce passage zones, which are stratigraphic surfaces marking major transitions in depositional environments. In glaciovolcanic settings, they record the elevations of syn-eruptive englacial lakes. Thus, they allow for forensic recovery of minimum ice thicknesses. Here we present the first description of a passage zone preserved entirely within pyroclastic deposits, marking the growth of a tephra cone above the englacial lake level. Our discovery requires extension of the passage-zone concept to accommodate explosive volcanism and guides future studies of hundreds of glaciovolcanic edifices on Earth and Mars. Our recognition of pyroclastic passage zones increases the potential for recovering transient paleolake levels, improving estimates of paleo-ice thicknesses and providing new constraints on paleoclimate models that consider the extents and timing of planetary glaciations.
Subglacial volcanoes host passage zones that can be used to define high stands of englacial lakes and paleo-ice thickness. This study identifies a pyroclastic passage zone in a subglacial volcano, which may help calculate transient paleolake levels and improve estimates of paleo-ice thickness.