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SUMMARY:How sharp is the Bottom Boundary of the Oceanic Plate? And why it 
 matters - Tolulope Olugboji\, University of Rochester
DTSTART:20201125T160000Z
DTEND:20201125T170000Z
UID:TALK151366@talks.cam.ac.uk
CONTACT:Camilla Penney
DESCRIPTION:A growing compilation of active and passive-source seismic sur
 veys reveal a transition across oceanic lithospheric plates that is sharp\
 , sometimes anisotropic\, and often marked by complex anisotropic layering
  underneath hotspot islands. A simple view of ocean plate formation and ev
 olution where thermal cooling governs with only a confined role for interm
 ittent hotspot/plume activity is challenged by these new seismic constrain
 ts. \nIn this presentation\, I discuss how new seismic constraints\, i.e.\
 , attenuation and age-dependence of a sharp low-velocity zone\, lend suppo
 rt to a subsolidus elastically accommodated grain-boundary sliding (EAGBS)
  model. We propose that this is the cause of the sharp seismic low-velocit
 y transition often referred to as the lithosphere-asthenosphere boundary (
 i.e. the underside of the oceanic plate). The EAGBS does not facilitate lo
 ng-term ductile deformation\, so the sharp seismic boundary may not coinci
 de with the conventional transition from lithosphere to asthenosphere corr
 esponding to a change in the long-term rheological properties. \n\n*This s
 eminar will be held online. Zoom details will be sent to members of the Ea
 rth Sciences department via email. Please contact the organisers if you ar
 e outside the department and would like to attend.*
LOCATION:ONLINE - Details to be sent by email
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