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SUMMARY:Coupling the thermodynamics and geodynamics of mantle melting: App
 lications to reactive channelisation beneath mid-ocean ridges - Lucy Tweed
 \, LDEO
DTSTART:20220309T160000Z
DTEND:20220309T170000Z
UID:TALK168044@talks.cam.ac.uk
CONTACT:Florian Millet
DESCRIPTION:The composition of magmas erupted at the surface are strongly 
 dependent on the dynamics of melt transport through the mantle. Holistic m
 odelling of melt transport processes requires consistent coupling of the t
 hermodynamics of melting and melt-rock reaction\, and geodynamics. However
 \, the high-dimensionality of such coupled problems presents a major theor
 etical and computational challenge. In this talk I will present a new ther
 modynamically consistent and tractable framework for integrating multicomp
 onent thermodynamics and multiphase geodynamics.\n\nA major question in te
 rrestrial magmatism is how mid-ocean ridge basalts sustain disequilibrium 
 with the uppermost mantle. This is generally explained by melt transport t
 hrough high-porosity channels\, which are thought to be formed through a r
 eactive channeling instability. However\, there remains significant questi
 ons about how and where channelisation is initiated. Here I apply our new 
 theoretical and software framework\, and present a series of 2D models to 
 investigate the formation of dunite channels in an upwelling harzburgitic 
 mantle column within the Mg2SiO4-SiO2 binary system. These models are the 
 first to self-consistently incorporate eutectic/peritectic melting into ma
 gma dynamics. We find that dunite channels can form via incongruent meltin
 g of harzburgite\, but only when there is a sustained flux of deep silica-
 poor melts. I will discuss what this implies about the melting conditions 
 beneath mid-ocean ridges.\n
LOCATION:In person (Wolfson) and ONLINE - Details to be sent by email
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