TEM image and high-resolution FORC diagram of lowest Eocene continental margin sediments from Wilson Lake,

New Jersey, demonstrating the occurrence of abundant biogenic magnetite.

SUMMARY

The ~55.5 Ma Paleocene-Eocene Thermal Maximum (PETM) is characterized by a significant perturbation to the global carbon cycle resulting from the rapid release of massive amounts of light carbon into the oceans and atmosphere. This carbon isotope excursion and the substantial rise in continental and sea surface temperatures make the PETM one of the best analogs we have for our current greenhouse conditions (the Anthropocene). A key concern today and in the past is how this warming alters the hydrologic cycle on land as well as nutrient delivery to and ecosystem productivity on the continental shelves. In 2004, we presented the first evidence demonstrating that the abundant fine-grained magnetite documented in Paleocene-Eocene boundary sediments from New Jersey was formed by bacteria; this finding was corroborated by more rigorous experiments in two independent studies a few years later (Lippert & Zachos; Kopp et al.). Modern forms of magnetotactic bacteria commonly live in the oxic–anoxic transition zone of aquatic environments where dissolved oxygen and sulfide are low and bioavailable iron is high. Thus, the restrictive ecological niche occupied by extant magnetotactic bacteria, as well as their preservation as magnetofossils, potentially make them biomarkers for unique environmental conditions. We are currently exploring relationships between magnetotactic bacteria diversity and nutrient availability during the PETM at shallow marine sites in New Jersey and California as part of a larger effort to study the feedbacks between climate change and changes in continental shelf ecology.

TEAM

1. James Zachos (UCSC), Amy Chen (Macquarie), Appy Sluijs (Utrecht), Steve Bohaty (Southampton)
   

FUNDING

1. NSF Biocomplexity, ARCS Foundation, Janice A. Newell Memorial Fund
   

PUBLICATIONS

1. Lippert, P.C., 2008. Big discovery for biogenic magnetite. Proceedings of the National Academy of Sciences of the United States of America, 105, 17595-17596,  doi:10.1073/pnas.0809839105.
   

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3. Lippert, P.C. and J.C. Zachos, 2007. A biogenic origin for anomalous fine-grained magnetic material at the Paleocene-Eocene boundary at Wilson Lake, New Jersey. Paleoceanography, 22, PA4104, doi:10.1029/2007PA001471.
   

4.     see also: Dickens, G. R., 2008, The riddle of the clays. Nature Geoscience, 1, p. 86-88.
   

PRESENTATIONS

1. Lippert, P.C., Dec. 2009. Magnetofossils as biomarkers of environmental change: A multiproxy example from the Paleocene-Eocene continental shelves of North America. EOS Trans AGU Fall Meet. Suppl., 90, Abstract GP42A-04. Invited talk
   

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3. Lippert, P.C. and J.C. Zachos, Sept. 2007. A biogenic origin for anomalous fine-grained magnetic particles at the Paleocene-Eocene boundary at Wilson Lake, NJ. 9th International Conference on Paleoceanography, Shanghai, P.R. China. Poster
   

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5. Lippert, P.C., J. Zachos, S. Bohaty, and T. Quattlebaum, Dec. 2004. Rock magnetic properties across Paleocene-Eocene boundary sediments from the North Atlantic, South Atlantic, and Eastern Pacific. EOS Trans., AGU, 85: Fall Meet., Suppl., Abstract GP31B-0840. Poster
   

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