Genetic Type of the Source Material for Common Leads

Abstract

RECENTTY the following formula was presumed^1,2 to hold in general between the concentration (C_x) of minor element X in a liquid and the corresponding concentration (C_x) in an infinitesimal solid just separated from the liquid: where k_x is defined as a partition coefficient of element X. Mathematical development of this general equation and application of its result to a triple combination of lead, thorium and uranium lead to³: and where C⁰ refers to concentration of subscripted element in the initial material for the Earth's oxide sphere. Equation (2) expresses the change of relative concentrations of the elements concerned in liquid, and equation (3) the corresponding change in solid, with the progress of crystallization of silicate melt. These equations indicate that the relative changes of logarithms of concentration in liquid and solid are expressed graphically by two straight lines running parallel with each other. In turn it is not only possible but also of much significance to decide whether a correlation observed for abundances of some elements represents liquid or solid