Seabed secrets in English clay( Fossilized organic molecules of green s...)

The fossils were found in sedimentary rock commonly used to make house bricks in England, quarried from what is called the Oxford Clay Formation.

The findings are reported in the May issue of the journal Geology (now online to subscribers.) Fabien Kenig, associate professor of earth and environmental sciences at the University of Illinois at Chicago, is the article's lead author. Contributors include John Hudson of the University of Leicester, Jaap Sinninghe Damst of the Royal Netherlands Institute for Sea Research and Brian Popp of the University of Hawaii.

Kenig and his colleagues have spent almost 15 years trying to learn why the bacteria -- which thrive only in oxygen-free but hydrogen sulfide-rich aquatic environments -- apparently co-existed with ancient, oxygen-breathing sea reptiles and other bottom-dwellers in a shallow part of a sea that's now the region of east-central England around Peterborough.

"It should have been one or the other," said Kenig. "You can't have both at the same time. They cannot co-exist."

Using solvents to extract oily lipids from sediments, the geologists identified the signature organic compounds of green sulfur bacteria using gas chromatographs and mass spectrometers.

"Molecules of green sulfur bacteria have a very specific, recognizable pattern or trace that allowed us to identify them in every sample of the Oxford Clay shale that we studied," said Kenig. "We found that their presence was not just an accidental find in a few samples, but corresponds to a recurring, ubiquitous process during deposition of those sediments."

A casual look at a piece of sedimentary rock embedded with fossils sugges
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Contact: Paul Francuch
francuch@uic.edu
312-996-3457
University of Illinois at Chicago
23-Apr-2004