  We report trace element concentrations of silicate phases in chondrules from
LL3 ordinary chondrites Bishunpur and Semarkona. Results are similar to
previously reported data for carbonaceous chondrites, with rare earth element
(REE) concentrations increasing in the sequence olivine < pyroxene <
mesostasis, and heavy REE (HREE) being enriched by 1-2 orders of magnitude
(CI-normalized) relative to light REE (LREE) in ferromagnesian silicates,
although no single olivine with very large LREE/HREE fractionation has been
found. On average, olivine in type II chondrules is poorer in refractory
lithophile incompatible elements (such as REE) than its type I counterpart by a
factor of ~2. This suggests that olivine in type I and II chondrules formed by
batch and fractional crystallization, respectively, implying that type II
chondrules formed under faster cooling rates (> ~ 10 K/h) than type I
chondrules. Appreciable Na concentrations (3-221 ppm) are measured in olivine
from both chondrule types; type II chondrules seem to have behaved as closed
systems, which may require chondrule formation in the vicinity of protoplanets
or planetesimals. At any rate, higher solid concentrations in type II chondrule
forming regions may explain the higher oxygen fugacities they record compared
to type I chondrules. Type I and type II chondrules formed in different
environments and the correlation between high solid concentrations and/or
oxygen fugacities with rapid cooling rates is a key constraint that chondrule
formation models must account for.
