Inter-element relationships between trace elements in primitive carbonaceous and unequilibrated ordinary chondrites

Abstract

The results of a search for significant (95 % confidence level) inter-element relationships among 13 trace elements in carbonaceous chondrites and 26 elements and the disequilibrium parameter for silicate phases in unequilibrated ordinary chondrites (UOC) indicate pronounced differences in the formation processes of these two sorts of primitive chondrites. Twenty-six pairs of elements are correlated in carbonaceous chondrites and these correlations lend support to a model involving mixing in different ratios of material differing in thermal history. Comparison of the 26 elements in UOC shows that 39 pairs of elements are significantly related and only very volatile elements are correlated with the disequilibrium parameter. Each of the inter-element relationships can be specifically ascribed to a metal-silicate fractionation in the solar nebula or to a thermal fractionation. These relationships are about equally consistent with the metamorphism, two-component condensation and simultaneous accretion-condensation models for the origin, of the ordinary chondrites, each requiring adoption of specific ad hoc assumptions for complete consistency.