Sulfidation of nano-magnetite to pyrite: Implications for interpreting paleoenvironmental proxies and biosignature records in hydrothermal sulfide deposits
Runge E, Mansor M, Shuster J, Fischer S, Liu Y, Lunter DJ, Kappler A, Duda JP (2023)
Publication Type: Journal article
Publication year: 2023
Journal
Original Authors: Eric A. Runge, Muammar Mansor, Jeremiah Shuster, Stefan Fischer, Yali Liu, Dominique J. Lunter, Andreas Kappler, Jan-Peter Duda
Book Volume: 617
Pages Range: 118261
Article Number: 118261
DOI: 10.1016/j.epsl.2023.118261
Abstract
Nano-magnetite is a potential archive for biosignatures and paleoenvironmental proxies in hydrothermal systems. However, sulfidic diagenesis at hydrothermal conditions potentially drives the rapid transformation of magnetite to Fe sulfide minerals. The identity and characteristics of transformation products from these reactions are crucial for interpreting biosignature records and paleoenvironmental proxies associated with Fe minerals in sulfide deposits. To constrain the preservation and transformation of magnetite in hydrothermal sulfide habitats, we incubated synthetic nano-magnetite in anoxic artificial seawater at a sulfide:Fe ratio of 4:1 as well as at different pH (7, 10) and temperatures (20-80 °C), and in presence or absence of added S0. Experimental products were analyzed by means of sequential Fe extraction, μ-X-ray diffraction (μ-XRD), Raman spectroscopy, and scanning electron microscopy (SEM). After 46 days, nano-magnetite was only detected at 20 °C (pH ∼10). Fe(III)-containing mackinawite and greigite formed at pH ∼10 and ≥20 °C. At pH ∼7 and 80 °C, magnetite was transformed to pyrite within only 19 days, with faster rates in the presence of polysulfides, which formed from the sulfide-mediated reduction of Fe(III) and in the presence of S0. Our results demonstrate a potential taphonomic bias against nano-magnetite in sulfidic hydrothermal habitats and suggest that pyrite-associated paleoenvironmental proxies and biosignature records of Fe- and S-cycling microorganisms in hydrothermal deposits are affected by diagenetic fluid-mineral interactions.
Involved external institutions
Germany (DE)How to cite
APA:
Runge, E., Mansor, M., Shuster, J., Fischer, S., Liu, Y., Lunter, D.J.,... Duda, J.-P. (2023). Sulfidation of nano-magnetite to pyrite: Implications for interpreting paleoenvironmental proxies and biosignature records in hydrothermal sulfide deposits. Earth and Planetary Science Letters, 617, 118261. https://doi.org/10.1016/j.epsl.2023.118261
MLA:
Runge, Eric, et al. "Sulfidation of nano-magnetite to pyrite: Implications for interpreting paleoenvironmental proxies and biosignature records in hydrothermal sulfide deposits." Earth and Planetary Science Letters 617 (2023): 118261.
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