A Nd isotopic study of the Hamersley and Michipicoten banded iron formations - The source of REE and Fe in Archean oceans

A detailed Nd isotopic study of the large and well-dated Hamersley and Michipicoten banded iron formations (BIFs) has been conducted. The Hamersley BIFs (Lake Superior type) are located in the Pilbara craton of Western Australia and the Michipicoten BIFs (Algoma type) are located in the northeastern corner of Lake Superior in Ontario, Canada. Their initial epsilon(Nd) values are variable and in the range of 0 to +4. The Fe/Nd ratio in present-day hydrothermal waters and BIFs are both 100,000, suggesting that the source of much of the Fe in BIFs (and Archean seawater) was hydrothermal water circulating through Archean midocean ridge systems.