Géochimie isotopique du lithium dans les basaltes-Géochimie des ...

tel-00344949, version 1 - 7 Dec 2008
3. Article soumis à GCA en révision
Figure 3.6 : Core to rim profile across the olivine 5‐20.
The compositions of the phases in FAMOUS picrites were extensively analyzed
�Bougault and Hekinian, 1974; Bryan, 1979; Kamenetsky, 1996; Laubier et al., 2007�, and
representative analyses obtained during the course of the present study are given in Table
3.1. Briefly, olivine phenocrysts are chemically homogeneous �Fig. 3.6� with high‐Mg
content �Fo88‐91�. Some crystals enclosed in the microcrystalline groundmass exhibit a Fe‐
rich rim �Fo82� restricted to the outer 10 μm boundary. This rim was produced by a late re‐
equilibration with the matrix. The few spinels we have analyzed in ARP73 10‐03 are
identical in composition to those studied by Kamenetsky �1996�. They are homogeneous
magnesiochromite �MgO � 16.7‐17.3 wt% and Cr2O3 � 41.6‐43.6 wt%� with a low TiO2
concentration
��0.36 wt%�.
98