Fractional crystallization causes the iron isotope contrast between mid-ocean ridge basalts and abyssal peridotites

Chen, Yanhong; Niu, Yaoling; Duan, Meng; Gong, Hongmei; Guo, Pengyuan

Abstract

The iron isotope contrast between mid-ocean ridge basalts and abyssal peridotites is far greater than can be explained by mantle melting alone. Here we investigate a suite of mid-ocean ridge magma chamber rocks sampled by the Ocean Drilling Project Hole 735B in the Atlantis Bank of the Indian Ocean. We report major and trace element geochemistry from these rocks and measure their iron isotope compositions to investigate the potential role of fractional crystallization during melt evolution. We observe a large range of δ56Fe that defines a significant inverse curvilinear correlation with bulk rock MgO/FeOT. These data confirm that δ56Fe in the melt increases as fractional crystallization proceeds but, contrary to expectation, δ56Fe continues to increase even when oxides begin to crystallize. We conclude that iron isotope fractionation through fractional crystallization during the evolution of mid-ocean ridge basalts from abyssal peridotites reconciles the disparity in isotopic compositions between these two lithologies.

Citation

Chen, Y., Niu, Y., Duan, M., Gong, H., & Guo, P. (2021). Fractional crystallization causes the iron isotope contrast between mid-ocean ridge basalts and abyssal peridotites. Communications Earth & Environment, 2(1), Article 65. https://doi.org/10.1038/s43247-021-00135-5

• Journal Article Type: Article
• Acceptance Date: Mar 1, 2021
• Online Publication Date: Mar 25, 2021
• Publication Date: 2021
• Deposit Date: Mar 25, 2021
• Publicly Available Date: Mar 25, 2021
• Journal: Nature Communications
• Electronic ISSN: 2662-4435
• Publisher: Nature Research
• Peer Reviewed: Peer Reviewed
• Volume: 2
• Issue: 1
• Article Number: 65
• DOI: https://doi.org/10.1038/s43247-021-00135-5
• Public URL: https://durham-repository.worktribe.com/output/1250435