  We used chemical equilibrium calculations to model thermal metamorphism of
ordinary chondritic material as a function of temperature, pressure, and trace
element abundance and use our results to discuss volatile mobilization during
thermal metamorphism of ordinary chondrite parent bodies. The calculations
include ~1,700 solids and gases of 40 elements. We compiled trace element
abundances in H-, L-, and LL-chondrites for the elements Ag, As, Au, Bi, Cd,
Cs, Cu, Ga, Ge, In, Pb, Rb, Sb, Se, Sn, Te, Tl, and Zn, and identified
abundance trends as a function of petrographic type within each class. We found
that abundance patterns within the H- and L- chondrites are consistent with
mobilization of volatile elements in an onionshell-type parent body.
LL-chondrites have more complex abundance patterns that may support a
rubble-pile model for the LL-chondrite parent body. We calculated volatility
sequences for the trace elements in the ordinary chondritic material, which
differs significantly from the solar nebula volatility sequence.
