V53A-3128
Feedback between deglaciation and volcanism in arc settings: the example of the Mount Mazama volcanic system, Crater Lake, Oregon
Friday, 18 December 2015
Poster Hall (Moscone South)
Carolyn Branecky1, Michael J Farner2, Tobias Keller3, Federica Lanza4, Gaia Siravo5, Helge Martin Gonnermann2, Peter J Huybers6, Michael Manga7 and Wouter van der Wal8, (1)University of California Santa Cruz, Santa Cruz, CA, United States, (2)Rice University, Houston, TX, United States, (3)University of Oxford, Oxford, United Kingdom, (4)Michigan Technological University, Geological and Mining Engineering and Sciences, Houghton, MI, United States, (5)Universita delgi Studi Roma Tre, Rome, Italy, (6)Harvard University, Cambridge, MA, United States, (7)University of California Berkeley, Berkeley, CA, United States, (8)Delft University of Technology, Delft, 5612, Netherlands
Abstract:
Previous studies have found correlations between glacial cycles and volcanism. Any such feedback mechanisms could have important implications for climate through variations in volcanic outgassing. Although decompression melting has been established as a cause for increased volcanism during deglaciation at mid-ocean ridge systems (Jull and McKenzie, 1996), it has not been determined how changes in glacial loading affect other settings such as volcanic arcs. We examine the Mount Mazama volcanic system, Oregon, where pulses of volcanism have been suggested to follow major deglaciations (Bacon et al. 2006). A statistical test regarding the timing of eruptions is first developed, and its application to eruption dates demonstrates statistically significant clustering of eruptions following deglaciation. To explore potential causes for the identified changes in probability of eruptions, the effects of glacial unloading on melt production are computed using a 1D mantle melting model, and the effect of ice unloading on shallow crustal stress conditions is tested with a viscoelastic stress model. Combining these effects into a simple eruption model, we propose that variations in melt supply rates from the mantle and changing stress conditions around a shallow crustal magma reservoir modulate eruption probability during glacial cycles. This model illustrates the physical plausibility of glacial variability causing the identified changes in eruption rates at Mt Mazama.
