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SUMMARY:One of the many relationships between mantle petrology and atmosph
 eric chemistry: The case of nitrogen. - Sami Mikhail\, University of St An
 drews
DTSTART:20160209T160000Z
DTEND:20160209T170000Z
UID:TALK61169@talks.cam.ac.uk
CONTACT:John Maclennan
DESCRIPTION:Understanding the chemical evolution of Earth’s atmosphere a
 nd hydrosphere is important\, especially with regard to the history of the
  buzzword-elements (e.g. COHNS). Of these elements\, nitrogen is of partic
 ular importance because it is an element that is fundamental to life\, a p
 otential hydrogen reservoir in the solid Earth\, and it also makes up most
  of the air we breath (Bebout et al.\, 2013).\nA major process in forming 
 planetary atmospheres is mantle degassing via volcanism and the primary co
 ntrol on what volatile elements are degassed by this process is their comp
 atibility in mantle minerals relative to melts and fluids. However\, becau
 se subduction happens on Earth\, it is also necessary to trace the partiti
 oning of volatiles through subduction systems over geological time to unde
 rstand the long-term co-evolution of the dynamic interior and habitable ex
 terior.\nIn the present\, the physiochemical conditions across different t
 ectonic settings cause speciation of nitrogen to vary from one tectonic se
 tting to another\, which means the behaviour of nitrogen during magmatism 
 and metasomatism in the mantle is not uniform (Mikhail & Sverjensky\, 2014
 \; Li & Keppler\, 2014). \nBy combining what is known about the speciation
  of nitrogen with data for the primordial noble gas abundances in the Eart
 h’s atmosphere\, and comparing these data with Earth’s tectonically ch
 allenged relatives (Mars and Venus)\, I have developed a dynamic model whi
 ch outlines how subduction zones have directly altered the composition of 
 Earth’s atmosphere through time.\n\nReferences cited (and further readin
 g for those who want more):\nBebout et al. 2013. Nitrogen: Highly volatile
  yet surprisingly compatible. Elements Magazine. 9\, 333-338 \nLi & Kepple
 r. 2014. Nitrogen speciation in mantle and crustal fluids. Geochimica Cosm
 ochimica et Acta\, 129\, 13–32\nMikhail & Sverjensky. 2014. Nitrogen spe
 ciation in upper mantle fluids and the origin of Earth’s nitrogen-rich a
 tmosphere. Nature Geoscience\, 7\, 816–819\n
LOCATION:Harker 1 seminar room\, Department of Earth Sciences
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