  We report in situ LA-ICP-MS trace element analyses of silicate phases in
olivine-bearing chondrules in the Sahara 97096 (EH3) enstatite chondrite. Most
olivine and enstatite present rare earth element (REE) patterns comparable to
their counterparts in type I chondrules in ordinary chondrites. They thus
likely share a similar igneous origin, likely under similar redox conditions.
The mesostasis however frequently shows negative Eu and/or Yb (and more rarely
Sm) anomalies, evidently out of equilibrium with olivine and enstatite. We
suggest that this reflects crystallization of oldhamite during a sulfidation
event, already inferred by others, during which the mesostasis was molten,
where the complementary positive Eu and Yb anomalies exhibited by oldhamite
would have possibly arisen due to a divalent state of these elements. Much of
this igneous oldhamite would have been expelled from the chondrules, presumably
by inertial acceleration or surface tension effects, and would have contributed
to the high abundance of opaque nodules found outside them in EH chondrites. In
two chondrules, olivine and enstatite exhibit negatively sloped REE patterns,
which may be an extreme manifestation of a general phenomenon (possibly linked
to near-liquidus partitioning) underlying the overabundance of light REE
observed in most chondrule silicates relative to equilibrium predictions. The
silicate phases in one of these two chondrules show complementary Eu, Yb and Sm
anomalies providing direct evidence for the postulated occurrence of the
divalent state for these elements at some stage in the formation reservoir of
enstatite chondrites. Our work supports the idea that the peculiarities of
enstatite chondrites may not require a condensation sequence at high C/O ratios
as has long been believed.
