[Geodynamics] Goldschmidt: 2018

Rhodri Davies rhodri.davies at anu.edu.au
Thu Feb 8 21:23:03 AEDT 2018


We are inviting submissions to the following Goldschmidt 2018 session:

02f: Mineralogy, Petrology and Processes in the Mantle Transition Zone and the Lower Mantle

which is convened by Greg Yaxley, Antony Burnham, Rhodri Davies and Mike Walter.

Our Key Note speaker will be Prof Robert van der Hilst (MIT). We also have an invited speaker - Dr Tim Jones (ANU and Carnegie). We are really hoping to attract talks and posters in which interpretation of geochemical and petrological observations on natural samples or high pressure experiments relevant to the mantle transition zone and lower mantle, can be informed by geophysics, mineral physics and geodynamics. We look forward to receiving your abstracts by the deadline of March 30. The session description is reproduced below.

The Earth’s mantle transition zone (MTZ) is that region of the mantle bounded by global seismic discontinuities at depths of 410 and 660 km. These depths closely correspond to phase transitions of upper mantle olivine to the wadsleyite structure and ringwoodite to bridgmanite and ferropericlase, respectively. The latter mineral assemblage is stable almost all the way to the outer core, with post-perovskite replacing bridgmanite only at the base of the lower mantle. Recent suggestions that these extremely deep parts of the earth may be very significant reservoirs of water, and inferences that some diamonds formed there, have profound implications for a range of petrological and physical processes, as well as for understanding the Earth’s deep water and carbon cycles. This session invites multidisciplinary contributions from geochemistry, petrology, geophysics, geodynamics and mineral physics that explore the nature of the MTZ and the lower mantle, and processes occurring within them. Questions to be addressed might include (1) How do sub-lithospheric diamonds and their inclusions form? (2) How do they get to the surface? (3) What do they tell us about the abundances, speciation and physical distribution of volatiles in the MTZ and lower mantle? (4) What lithologies are present, what are their chemical compositions and physical distributions, and how does this relate to the isotopic variability seen in oceanic basalts? (5) What are the physical properties of the MTZ and lower mantle and what constraints do they place on chemistry and mineralogy? (6) What effects do volatiles have on physical properties of these lithologies under the relevant conditions? (7) What is the temperature distribution in the MTZ and lower mantle? (8) Could melts exist there? (9) What roles do deeply subducted slabs play in MTZ and lower mantle processes?

Yours sincerely

Greg Yaxley
Antony Burnham
Rhodri Davies
Mike Walter

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