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Synchrotron X-ray scan for chemical analysis and imaging of fossils
From: Ben Creisler
A new paper of interest. The pdf is free at the download link:
N.P. Edwards, R.A. Wogelius, U. Bergmann, P. Larson, W.I. Sellers,
P.L. Manning (2012)
Mapping Prehistoric Ghosts in the Synchrotron.
Applied Physics A (advance publication)
The detailed chemical analysis of fossils has the potential to reveal
great insight to the composition, preservation and biochemistry of
ancient life. Such analyses would ideally identify, quantify, and
spatially resolve the chemical composition of preserved bone and soft
tissue structures, but also the embedding matrix. Mapping the
chemistry of a fossil in situ can place constraints on mass transfer
between the enclosing matrix and the preserved organism(s), and
therefore aid in distinguishing taphonomic processes from original
chemical zonation remnant within the fossils themselves. Conventional
analytical methods, such as scanning electron
microscopy (SEM) and pyrolysis–gas chromatography/mass spectrometry
(Py-GC/MS) have serious limitations in this case, primarily, an
inability to provide large (i.e., decimeter) scale chemical maps.
Additionally, vacuum chamber size and the need for destructive
sampling preclude analysis of large and precious fossil specimens.
However, the recent development of Synchrotron Rapid Scanning X-ray
Fluorescence (SRS-XRF) at the Stanford Synchrotron Radiation
Lightsource (SSRL) allows the non-destructive chemical analysis and
imaging of major, minor, and trace element concentrations of large
paleontological and archeological specimens in rapid scanning times.
Here we present elemental maps of a fossil reptile produced using the
new SRS-XRF method. Our results unequivocally show that preserved
biological structures are not simply impressions or carbonized
remains, but possess a remnant of the original organismal
biochemistry. We show that SRS-XRF is a powerful new tool for the
study of paleontological and archaeological samples.
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