Meteoritic Bismuth and ^(208)Pb Microdistributions

Abstract

Certain types of meteorites are believed to be the most primitive solar system objects available. Bismuth and lead microdistributions in these are of interest because (a) predictions for the condensation of these elements are available from thermodynamic calculations for equilibrium, gas-to-solid condensation in a cooling nebula of solar composition; (b) based on this theory, bulk bismuth contents have been used for inferring the temperatures at which solids in the solar nebula accreted, as well as the extant nebular pressures; and (c) due to their volatility, these elements are easily mobilized in metamorphic (reheating) events and are thus sensitive indicators of planetary processing of the meteoritic material. With the idea of testing, where possible, the equilibrium condensation theory (a) and its ramifications (b) and of assessing the nature and evolution of early bodies in the solar system (c), we have been studying the bismuth and ^(208)Pb microdistributions in unequilibrated chondritic meteorites.