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SUMMARY:Silica enrichment (and depletion) in the cratonic lithosphere - Em
 ma Tomlinson\, Trinity College Dublin
DTSTART:20250520T110000Z
DTEND:20250520T120000Z
UID:TALK224737@talks.cam.ac.uk
CONTACT:Dr Rachael Rhodes
DESCRIPTION:It is well established that the cratonic lithospheric mantle f
 ormed as a residue of extensive mantle melting during the Archaean. Howeve
 r\, an unexpected feature of peridotite xenoliths from the cratonic lithos
 phere is that they exhibit silica contents that extend both above and belo
 w that expected after simple peridotite melting\, implying a role for open
  system processes. High-silica peridotites\, rich in orthopyroxene\, are c
 ommonly found in the Kaapvaal and Siberian cratons\, whereas low-silica sa
 mples\, such as those from parts of Greenland and Tanzania contain anomalo
 usly high olivine. Komatiites are produced by advanced peridotite melting 
 and predominantly erupted during the Archean\, observations that appear to
  compliment the highly refractory nature of Archean peridotites. However\,
  a simple melt-residue relationship is undermined by observations that bot
 h komatiite and cratonic peridotite have depleted initial Hf-isotope compo
 sitions. Using insights from petrology\, thermodynamic modelling\, geochem
 istry and high pressure experiments\, this talk will investigate the condi
 tions of silica enrichment and discuss a potential role for komatiite-peri
 dotite interaction.
LOCATION:Department of Earth Sciences\, Tilley Lecture Theatre
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