HR: 0800h
AN: B31D-0620 [Abstracts]
TI: Possible Eukaryotic Magnetite in the Paleocene-Eocene Boundary Clay, Ancora, New Jersey
AU: Schumann, D
EM: schumann@eps.mcgill.ca
AF: Department of Earth and Planetary Sciences, McGill University, 3640 University Street,
Montreal, QC H3A 2B2, Canada
AU: Raub, T D
EM: timothy.raub@yale.edu
AF: Department of Geology and Geophysics, Yale University, P.O. Box 208109, New Haven, CT
06520-8109, United States
AU: Raub, T D
EM: timothy.raub@yale.edu
AF: Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E.
California Blvd., Pasadena, CA 91125, United States
AU: Kopp, R E
EM: rkopp@caltech.edu
AF: Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E.
California Blvd., Pasadena, CA 91125, United States
AU: Tikoo, S M
EM: samtechs@gmail.com
AF: Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E.
California Blvd., Pasadena, CA 91125, United States
AU: Sears, S K
EM: sksears@eps.mcgill.ca
AF: Department of Earth and Planetary Sciences, McGill University, 3640 University Street,
Montreal, QC H3A 2B2, Canada
AU: Leucken, U
EM: uwe.lucken@fei.com
AF: FEI Company,
Nanobiology Marketing, Building AAE-I-1-340,
Achtseweg Noord 5,
P.O. Box 80066, Eindhoven, 5600KA, Netherlands
AU: Rouiller, I
EM: isabelle.rouiller@mcgill.ca
AF: Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montreal,
QC H3A 2B2, Canada
AU: Smirnov, A V
EM: aleksey.smirnov@yale.edu
AF: Department of Geology and Geophysics, Yale University, P.O. Box 208109, New Haven, CT
06520-8109, United States
AU: Kirschvink, J L
EM: kirschvink@caltech.edu
AF: Division of Geological and Planetary Sciences, California Institute of Technology, 1200 E.
California Blvd., Pasadena, CA 91125, United States
AU: * Vali, H
EM: vali@eps.mcgill.ca
AF: Department of Earth and Planetary Sciences, McGill University, 3640 University Street,
Montreal, QC H3A 2B2, Canada
AU: * Vali, H
EM: vali@eps.mcgill.ca
AF: Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montreal,
QC H3A 2B2, Canada
AB:
We report the discovery of new forms of magnetic particles in the Paleocene-Eocene (P-E) boundary clay from the
borehole at Ancora, New Jersey (Ocean Drilling Program Leg 174AX). The P-E boundary clay shows anomalous
magnetic properties suggesting enrichment in single-domain (SD) magnetite. Transmission electron microscopy
of the magnetic separates shows that the majority of the SD particles are magnetofossils of known crystal shape
and size [1]. There are, however, larger magnetite particles having unusual morphology, including: (1) elongated
prismatic magnetite of 100 nm width and up to 1 micron length, (2) leaflike magnetite particles up to 2 microns in
length, and (3) elongated, conelike particles with an aspect ratio of 4:1. Lattice-fringe images and X-ray
microanalysis of these particles show single-crystal structure and stochiometric magnetite composition, similar
to magnetite crystals produced by magnetotactic bacteria. Although the dimensions of some of the type 2 and type
3 particles are outside that expected for single-domain behaviour as typically calculated for parallelepipeds and
ellipsoids [2], electron holographic analysis reveals a SD signature. It is likely that these magnetic particles are of
biogenic origin, as we were unable to find significant amounts of obviously detrital magnetite in the sediments. As
these unusual magnetic particles are confined to the narrow P-E boundary layer, environmental changes along
the eastern Atlantic margin of North America during the Paleocene-Eocene Thermal Maximum (PETM) may have
led to enhanced growth, and perhaps diversification, of magnetite-forming microorganisms. The dimensions of
the observed magnetite particles, however, exceed the size of prokaryotes; if they were, indeed, biogenic, they
were likely formed by an unknown eukaryotic organism.
References: [1] R. E. Kopp et al., 2007. Paleoceanography (in press). [2] R. E. Kopp and J. L. Kirschvink, 2007.
Earth Science Reviews. doi:10.1016/j.earscirev.2007.08.001.
DE: 0419 Biomineralization
DE: 0424 Biosignatures and proxies
DE: 0448 Geomicrobiology
DE: 1505 Biogenic magnetic minerals
DE: 1540 Rock and mineral magnetism
SC: Biogeosciences [B]
MN: 2007 Fall Meeting