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SUMMARY:Towards the origins of lower-mantle heterogeneities: from seismic 
 models to mineral physics (***CANCELLED DUE TO STRIKES***) - Wenzhong Wang
  (Carnegie Institute)
DTSTART:20211201T160000Z
DTEND:20211201T170000Z
UID:TALK162001@talks.cam.ac.uk
CONTACT:Sam Wimpenny
DESCRIPTION:The lower mantle is the largest continuous layer within Earth.
  It plays a dominant role in the thermochemical and geodynamic evolution o
 f the planet. Seismic studies have revealed numerous heterogeneities with 
 different length scales in the lower mantle\, including the small-scale se
 ismic scatterers and the Large Low Shear Velocity Provinces (LLSVPs) benea
 th Africa and the Pacific in the lowermost mantle.  Seismic models suggest
  that the thickness of scatterers is only several or tens of kilometers wi
 th a velocity perturbation of < 1% throughout the mantle\, but the shear v
 elocity could be up to ~ 12% lower than the surrounding mantle in the mid 
 mantle. Meanwhile\,  the systematic observations in seismic properties ind
 icate that the LLVSPs are likely composed of distinct chemical materials f
 rom the surrounding mantle. Their origins have long been debated\, with hy
 potheses ranging from subducted oceanic crust and to primordial materials.
  In this talk\, I'll discuss whether subducted oceanic crust can explain t
 he lower-mantle heterogeneities or not based on our recent theoretical res
 ults. I'll also show our experimental findings to help understand how the 
 early magma redox reaction would have produced distinct materials that may
  be responsible for LLSVPs.\n
LOCATION:ONLINE - Details to be sent by email
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