|
|
|
|
life in the Archaean
biomarker record of phototrophic sulfur bacteria.
figure courtesy of j.j. brocks
|
Biomarkers are an effective tool for reconstructing really ancient microbial ecosystems and learning more about the timescales over which major biochemical and physiological innovations took place. In pursuit of this aim we have been undertaking a search for well preserved Archaean and Paleoproterozoic rocks that might have indigenous organic matter with potential for biomarker studies. Beginning in 1999, Jochen Brocks realized this possibility with his groundbreaking studies of hydrocarbons extracted from organic-rich sediments from the ca. 2700 million years old Fortescue Group of the Pilbara Craton, Western Australia. Follow-up studies by Jennifer Eigenbrode of Penn State University in different sediments from the same basin have revealed equally profound results pointing to long history of cyanobacteria, green sulfur bacteria and eukaryotes recorded in kerogens derived from Archean microbes.
|
location of barney creek formation in austrailia, which contains 2.7 billion year-old well-preserved organic matter.
figure courtesy of j.j. brocks
|
Support: NASA Exobiology Program
Publications:
Summons R.E., Jahnke L.L., Logan G.A. and Hope J.M. (1999) 2-Methylhopanoids as biomarkers for cyanobacterial oxygenic photosynthesis. Nature 398: 554-7.
Brocks J.J., Logan G.A., Buick R. and Summons R.E. (1999) Archean molecular fossils and the early rise of eukyotes. Science 285: 1033-6.
Brocks J.J., Love G.D., Snape C.E., Logan G.A., Summons R.E. and Buick R. (2003) Release of bound aromatic hydrocarbons from late Archean and Mesoproterozoic kerogens via hydropyrolysis. Geochimica et Cosmochmica Acta 67: 1521-1530.
Brocks J.J., Summons R.E., Logan G.A. and Buick R. (2003) Molecular Fossils in Archean rocks II: Composition, thermal maturity and integrity of hydrocarbons extracted from sedimentary rocks of the 2.78 2.45 billion years old Mount Bruce Supergroup, Pilbara Craton, Western Australia. Geochimica et Cosmochmica Acta 67: 4289-4319.
Brocks J.J., Buick R., Summons R.E. and Logan G.A. (2003) A reconstruction of Archean biological diversity based on molecular fossils from the 2.78 - 2.45 billion year old Mount Bruce Supergroup, Hamersley Basin, Western Australia. Geochimica et Cosmochmica Acta 67: 4321-4335.
Brocks J. J., Summons R. E., Buick R., and Logan G. A. (2003) Origin and significance of aromatic hydrocarbons in giant iron ore deposits of the late Archean Hamersley Basin in Western Australia. Organic Geochemistry 34: 1161-1175.
Eigenbrode J.L., Freeman K.H., Summons R.E., Love G.D., Snape C.E. (2003) Biomarkers Indigenous to Late Archean Rocks Eos Trans. AGU, 84(46), Fall Meet. Suppl., Abstract U52B-05.
Sturt H.F., Summons R.E., Smith K., Elvert M. and Hinrichs K.-U. (2004) Intact polar membrane lipids in prokaryotes and sediments deciphered by ESI-HPLC-MSn new biomarkers for biogeochemistry and microbial ecology. Rapid Communications in Mass Spectrometry, In Press.
Rothman D.H., Hayes J.M. and Summons R.E. (2003) Dynamics of the Neoproterozoic Carbon Cycle. Eos Trans. AGU, 84(46), Fall Meet. Suppl., Abstract U52C-05.
Brocks J.J., Love G.D., Logan G.A. and Summons R.E. (2004). Okenane: a new carotenoid biomarker for purple sulfur bacteria (Chromatiaceae) and evidence for intense photic-zone euxinia in the Paleoproterozoic Barney Creek Formation, McArthur Basin, NT. Abstracts with Program, Australian Organic Geochemistry Conference, Leura NSW Australia. |
|
