Iron Isotope Fractionation During Magmatic Differentiation in Kilauea Iki Lava Lake

• DOI: 10.1126/science.1157166
• Publication Date: 2008-06-19T23:38:09Z
• Authors: Fang-Zhen Teng; Nicolas Dauphas; Rosalind T. Helz
• Keywords: magmatic differentiation ; Fe-isotopes ; Kilauea Iki Lava Lake; 13. Climate action; 01 natural sciences; 0105 earth and related environmental sciences

Magmatic differentiation helps produce the chemical and petrographic diversity of terrestrial rocks. The extent to which magmatic differentiation fractionates nonradiogenic isotopes is uncertain for some elements. We report analyses of iron isotopes in basalts from Kilauea Iki lava lake, Hawaii. The iron isotopic compositions ( 56 Fe/ 54 Fe) of late-stagemeltveins are 0.2 permil (‰) greater than values for olivine cumulates. Olivine phenocrysts are up to 1.2‰ lighter than those of whole rocks. These results demonstrate that iron isotopes fractionate during magmatic differentiation at both whole-rock and crystal scales. This characteristic of iron relative to the characteristics of magnesium and lithium, for which no fractionation has been found, may be related to its complex redox chemistry in magmatic systems and makes iron a potential tool for studying planetary differentiation.