COMPOSITIONAL AND GENETIC RELATIONSHIP BETWEEN CHONDRULES, CHONDRULE RIMS, METAL, AND MATRIX IN THE RENAZZO CHONDRITE

Abstract

Individual chondrules, coarse and fine-grained metal, chondrule rims, and matrix samples were separated from the Renazzo chondrite (CR2) and studied by instrumental neutron activation analysis. Both Renazzo chondrule and matrix fractions have CI Cr/Mg concentration ratios, unlike chondrules from other classes of chondrites, which have fractionated Cr/Mg ratios. This and other arguments suggest that Renazzo chondrules and matrix formed in the same nebular region. In Renazzo, fine-grained metal—the dominant metal component, is mostly located inside chondrules or in chondrule rims. Matrix contains few coarse metal grains. Both types of metal, fine and coarse, exhibit similar chemical signatures, comparatively high in Cr and low in Ni, suggesting a genetic relationship.