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

tel-00344949, version 1 - 7 Dec 2008
3. Article soumis à GCA en révision
Figure 3.10 : Maximum modification of the δ7Li in olivine rims during
diffusion‐induced isotopic fractionation. The calculations were made fo
various values of the parameters β and Do for �a� an Ea equivalent to the
pyroxene and �b� for an Ea 30% lower. These calculations were realized for
two olivines at different depths within the pillow, using the cooling paths
shown in Fig. 3.9. The two fields correspond to the values of the diffusion
parameters for which the calculations reproduce the δ7Li r
variations observed
in Ol4‐11 �grey field� and in Ol5‐20 �hatched field�. The intersection of the
two fields constrains β in olivine to range from �0.3 to �0.5.
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