FRACTIONAL CRYSTALLIZATION OF IRON-METEORITES - CONSTANT VERSUS CHANGING PARTITION-COEFFICIENTS

Analyses of magmatic iron meteorites, plotted on LogC(i) vs. LogC(Ni) diagrams, often form linear arrays. Traditionally, this linearity has been ascribed to fractional crystallization under the assumption of co nstant partition coefficients (i.e., Rayleigh fractionation). Paradoxi cally, however, partition coefficients in the Fe-Ni-S-P system are dec idedly not constant. This contribution provides a rationale for unders tanding how trends on LogC(i) vs. LogC(Ni) diagrams can be linear, eve n when partition coefficients are changing rapidly.