Diversification of Iron‐Biomineralizing Organisms During the Paleocene‐Eocene Thermal Maximum: Evidence From Quantitative Unmixing of Magnetic Signatures of Conventional and Giant Magnetofossils
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- Courtney L. Wagner
- Department of Geology and Geophysics University of Utah Salt Lake City UT USA
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- Ioan Lascu
- Department of Mineral Sciences National Museum of Natural History Smithsonian Institution Washington DC USA
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- Peter C. Lippert
- Department of Geology and Geophysics University of Utah Salt Lake City UT USA
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- Ramon Egli
- Division of Data, Methods and Models Central Institute of Meteorology and Geodynamics (ZAMG) Vienna Austria
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- Kenneth J. T. Livi
- Materials Characterization and Processing Center Department of Materials Sciences and Engineering Johns Hopkins University Baltimore MD USA
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- Helen B. Sears
- Department of Geology Colby College Waterville ME USA
抄録
<jats:title>Abstract</jats:title><jats:p>Conventional magnetofossils represent magnetic mineral remains of magnetotactic bacteria. Giant magnetofossils have no known modern analog. Both conventional and giant magnetofossil assemblages can record paleoenvironmental information through changes in magnetotactic bacteria diversity driven by nutrient supply and oxygenation. We use marine sediments that record a rapid global warming event, the Paleocene‐Eocene Thermal Maximum (∼56 Ma), to assess how abundant well‐preserved magnetofossils with high morphological disparity record paleoenvironmental information. We find that conventional magnetofossils can be distinguished from giant, needle‐shaped magnetofossils using principal component analysis of first‐order reversal curves (FORC‐PCA); moreover, FORC‐PCA may be able to distinguish between well‐preserved magnetically soft and magnetically hard magnetofossils. FORC‐PCA is a robust, nondestructive technique that can be applied to other marine archives to understand how these ecosystems respond to rapid environmental change. We hypothesize that the sudden appearance of giant magnetofossils represents a natural response to niche expansion within the water column (a thicker oxic‐anoxic interface) and eutrophication (<jats:italic>via</jats:italic> iron supply) by protists that biomineralize giant magnetofossils. This application has potential as a proxy for changes in marine oxygen and iron concentrations stimulated by rapid planetary change.</jats:p>
収録刊行物
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- Paleoceanography and Paleoclimatology
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Paleoceanography and Paleoclimatology 36 (5), 2021-05
American Geophysical Union (AGU)