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CATEGORIES:Sedgwick Club talks
SUMMARY:Changing the paradigm - new views of magmatic syst
 ems provide new perspectives on volcanic processes
  - Professor Katharine Cashman (University of Bris
 tol)
DTSTART;TZID=Europe/London:20160125T170000
DTEND;TZID=Europe/London:20160125T180000
UID:TALK62372AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/62372
DESCRIPTION:Igneous petrology is undergoing a major paradigm s
 hift. For the past century\, the paradigm of the m
 agma chamber - a single\, melt-dominated magma bod
 y - has informed models of magma evolution and und
 erpinned studies of volcanic processes. Over the p
 ast decade\, however\, the community has converted
  to a model of complex magma storage regions compo
 sed primarily of crystal-rich "mush"\, with crysta
 l-poor melt partitioned into sill-like lenses that
  can be tapped\, either sequentially or simultaneo
 usly\, to feed volcanic eruptions. Why has this co
 nceptual shift occurred? Evidence for complex magm
 a storage regions derives from numerous sources\, 
 including (1) geophysical evidence for sill-like m
 elt bodies\, (2) petrologic studies\, which provid
 e strong evidence that many erupted magma contain 
 crystals that have been incorporated from differen
 t parts of the magma storage region\, and over dif
 ferent time scales\, and (3) geochemical evidence 
 that magmatic gases may accumulate and be released
  independently from the melt. These observations s
 uggest that magma storage regions are not only com
 plex\, but also dynamic\, in that the solid (cryst
 al)\, liquid (melt) and gas (exsolved volatiles) c
 omponents may move and interact at different rates
 . Critically\, adopting a melt-mush model requires
  a re-evaluation of processes responsible for melt
  segregation\, evolution and eruption. For example
 \, melt segregation and evolution may depend more 
 on processes related to reactive flow of melts and
  fluids through porous crystal networks than sinki
 ng or floating of crystals within a (dominantly li
 quid) body. Additionally\, patterns of eruptive be
 haviour may be determined as much by the stability
  of\, and interactions between\, individual melt l
 enses as by the evolution of a single melt body. F
 rom this perspective\, studies of volcanic process
 es can be linked directly to processes of magma ge
 neration and evolution. Forging these links provid
 es an exciting challenge for the future.
LOCATION:Harker Room 1\, Department of Earth Sciences
CONTACT:Matouš Ptáček
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