AGU 2016

I will be at AGU for the whole week.  On Monday afternoon I will presenting work we have been doing combining new Fe-XANES observations and thermodynamic models of mantle melting to understand solid Earth redox.  On Wednesday afternoon Paula Antoshechkina will be presenting our preliminary model incorporating carbonate melting into the pMELTS thermodynamic framework.  See you in San Francisco!

The solid Earth’s involvement in oxygen cycling: Observations and theory

Authors: Oliver Shorttle, Edward Stolper, Paula Antoshechkina, Paul Asimow, Eleanor Jennings, Glenn Gaetani, David Graham, Margaret Hartley, Helen Williams, Maryjo Brounce, Saemundur Halldorsson

Session: V13B Magmatic and Tectonic Influences on Elemental Cycling and Earth’s Climate and Oxidation State Posters

When/where: Monday 12th December, 13:40 – 18:00 in Moscone South – poster hall

We have undertaken a targeted study of basalts erupted along the South East Indian Ridge to test the relative controls of mantle temperature and chemical heterogeneity on Fe3+/ΣFe.  Among this suite of basalts there is short length scale heterogeneity and a long wavelength transition to cooler mantle.  Despite these factors, the Fe3+/ΣFe and the oxidation state of erupted basalts is remarkably uniform.  This result suggests that basalt  fO2 is being buffered during mantle melt extraction.

Silicate and Carbonatite Melts in the Mantle: Adding CO2to the pMELTS Thermodynamic Model of Silicate Phase Equilibria

Authors: Paula Antoshechkina, Oliver Shorttle

Session: V33C Deep Carbon: From the Mantle to the Surface and Back Again III Posters

When/where: Wednesday 14th December, 13:40 – 18:00 in Moscone South – poster hall

The transport of carbon in the mantle via carbonated melting of peridotite is critical for the solid Earth volatile cycle, yet most models of mantle melting only consider the thermodynamics of silicate melting and treat carbon as a trace species.  To address this issue and form a self-consistent thermodynamic description of carbonated peridotite melting we have expanded and updated the CO2-fluid database constructed by Ghiorso and Gualda (2012, 2015) to include more recent high pressure experiments.  In the initial stages of calibrating the model a key question we will answer is whether a Na2CO3 liquid component is required in addition to CaCO3.