GSA Special Session: Supervolcanoes, Ignimbrite Flare-ups, and Their Impacts: Definition, Debate, and New Developments
From: Shan de Silva <desilvas@xxxxxxxxxxxxxxxxxxx>
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The deadline of August 11, 2009
is fast approaching for the 2009 Geological Society of America National Meeting, to be held in, Portland, Oregon (USA), October 18-21, 2009.
PLEASE CONSIDER CONTRIBUTING TO THE FOLLOWING TOPICAL SESSION
T65. Supervolcanoes, Ignimbrite Flare-ups, and Their Impacts: Definition, Debate, and New Developments
Conveners: Shan de Silva, Ilya Bindeman, Jake Lowenstern
Super-eruptions are thought to be the most devastating of terrestrial geologic phenomena with extreme impacts on the earth system that still remain to be fully understood. This session critically examines definitions, new developments, and current debate.
Invited contributors:
Stephen Self (NRC, USA)
Clive Oppenheimer (Cambridge, UK)
Bill Rose (MTU, USA)
Rationale:
Our aim in this session is to critically assess the current state of knowledge about supervolcanic systems. We hope to focus on three themes. The size of supereruptions, the volcanology of supereruptions, and the surface record of volcanism.
Since there is no strict definition of a super-volcano, the term is generally used to characterize explosive volcanic eruptions very much larger than eruptions that have so far affected humanity in the short course of recorded human history. Typically these are caldera forming eruptions with a VEI (Volcanic Explosivity Index) of >8, that resulted in the deposition of 1000?s of km3 of regionally extensive ignimbrites (approximately 100x the 1991 Pinatubo eruption). Since no supereruptions have been observed, much of the impact of these volcanoes is based on a scaling of well characterized eruptions such as the 1815 Tambora eruption to supervolcanic proportions. But what exactly is supervolcanic proportion? The methodology and veracity of the volume estimates of supervolcanic eruptions is a matter of some debate and needs to clarified before their scaled impact can be assessed adequately.
Recently, well studied supereruptions reveal that they may not simply be scaled-up versions of well characterized major historic eruptions. Many supereruptions are of highly crystal-rich magma. What do we know about the eruption and emplacement of these magmas? Is there evidence for the association of extensive ashfalls with these ignimbrites. Are current models of the effective stratospheric aerosol input associated with these eruptions concordant with our understanding of the volcanology and petrology of these eruptions?
Over what time scales do supervolcanic systems develop and operate? This question is typically addressed from the magmatic perspective rather than the volcanic perspective; a crystallization history is unraveled with micro-geochronometry of accessory phases. However, equally important is to understand the space-time-volume histories of long-lived well characterized supervolcanic systems as the surface record of the magmatic history beneath. This is not just to understand repose periods of these systems, but understanding individual caldera systems as well as ignimbrite or supervolcano flare-ups allows fundamental questions about the development of supervolcanic systems to be addressed. How has our understanding of the volcanic and geologic histories of these systems developed in the last decade or so?
We invite contributions that will shed light on these issues and demonstrate the state of our knowledge about supereruptions and supervolcanism.
For more information:
http://www.geosociety.org/meetings/2009/sessions/topical.asp?CatID=Volcanology&submit=Go
Jake Lowernstern
Ilya Bindeman
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