par- 8 octobre 2018
Project PIs : Alexander Sobolev (ISTerre) corresponding PI- responsible for mantle -core part ;
John Valley (Wisconsin-Madison UNI, USA)- responsible for crustal part and SIMS ;
Stephan Sobolev (GFZ, Potsdam, Germany)- responsible for geodynamic modeling.
The goal of MEET is to monitor and understand the compositional evolution of the terrestrial mantle, and crust from the Archean to the Phanerozoic times. We will use compositions and temperatures of primary mantle-derived melts reconstructed from the study of melt inclusions in olivine form komatiites and picrites to constrain evolution of mantle composition. We will further study formation of the crust based on composition of melt inclusions and host zircons and finally we will integrate our observations using geodynamic models of mantle convection and plate tectonics. We aim to measure an extensive range of geochemical parameters, including mobile and volatile element (Pb, B, Rb, Ba, Sr, Cl, S, H2O, CO2) concentrations and isotopic compositions of H, O, B, Cl, C, S, Sr, and Pb in homogenized melt inclusions and the elemental and O isotopic compositions of host olivines and O, Hf and Pb isotope composition of zircons. We will analyses samples from 25 localities of komatiites and picrites that originated at different depths and cratons between 3.7 and 0.09 Ga and detrital and magmatic zircons covering ages between 4.4 Ga till 1 Ma. We will apply published and new models to constrain the temperatures and compositions of their mantle and crustal sources and use geodynamic modelling to relate our observations to the evolution of mantle convection, crustal production and plate tectonics. MEET will, therefore, address the following issues : the rate of crustal growth and recycling through time ; the cause and timing of the onset of large-scale subduction and plate tectonics and factors controlling its evolution ; the concentration and origin of H2O and halogens in the deep mantle, and the extent (if any) of core-mantle interaction.
We : Alexander Sobolev and Stephan Sobolev will present our vision of project in 30-minute talks. Goal is to attract scientists of ISTerre to participate in the project with possible funding.
As part of the project we intend to buy and set up in ISTerre LA-ICP MS-MC-ICP MS split stream system for in-situ microanalysis of trace elements and isotopes.
Friday 12 October - 14h30 - Room Dolomieu (3rd floor)
ISTerre - 1381 rue de la Piscine - Grenoble Campus
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