Fig. 4: Diagram of δ56/54Fe versus FeO.
From: Isotopic evolution of planetary crusts by hypervelocity impacts evidenced by Fe in microtektites
The shaded horizontal area indicates the Fe isotopic composition in macroscopic Australasian tektites. The average composition of the upper continental crust (FeO = 6.9 wt%, δ56/54Fe = −0.263‰) suggested to be the starting composition for the Australasian strewn field. A range of Rayleigh evaporation trends predicted using different fractionation factors α are shown. The Rayleigh fractionation trend under ideal conditions of evaporation to vacuum predicted by the Hertz–Knudsen equation is shown as a thick line. The downward shift of certain microtektites from the upper crust δ56/54Fe–FeO composition is best explained by a mixing line between the pristine melt and condensed components.
