HR: 0800h
AN: P51D-0966    [Abstracts]
TI: Microbe-mineral interactions: understanding biomarker formation in modern Earth systems.
AU: * Leveille, R J
EM: richard.leveille@space.gc.ca
AF: Canadian Space Agency, 6767 Route de l'Aeroport, Longueuil, QC J3Y 8Y9 Canada
AB: The discovery of a microbial cell beyond Earth is often viewed as the proverbial "smoking gun" required for demonstrating beyond a doubt the existence of extraterrestrial life. However, studies of modern Earth systems have shown that the preservation of bacterial cells is a rare phenomenon that requires very specific physicochemical conditions. Similarly, many presumed remains of microbial cells observed in the rock record are now thought to be abiogenic mineral structures. More commonly, the complex interactions between microorganisms and their environment lead to the formation of physical, chemical and isotopic biomarkers that are more readily preserved in the rock record. This is especially true for microbe-mineral interactions whereby minerals with characteristic textures, crystal structure, chemistry or isotopic composition are produced, often in combination with specific biochemical signatures. Such mineral biomarkers not only provide information about the organisms that created them, but also help to elucidate the environmental conditions under which they were created and the biogeochemical processes involved in their formation and preservation. The discovery of a suite of robust biomarkers on Mars would therefore not only provide proof of the existence of extraterrestrial life, but would also help in understanding the geological and chemical context of past life on Mars. Hence, studies of modern systems on Earth are essential for elucidating how these biomarkers are formed and ultimately preserved in the rock record. This information can in turn be applied directly to the development of planetary exploration strategies and science instrument payloads. Here, a number of recent examples of microbe-mineral interactions in modern systems, from terrestrial and subsurface basalts to deep-sea hydrothermal vents and cold seeps, are reviewed and the key mineralogical, molecular, isotopic and elemental signatures formed in these systems are summarized.
DE: 0406 Astrobiology and extraterrestrial materials
DE: 0419 Biomineralization
DE: 0424 Biosignatures and proxies
DE: 6207 Comparative planetology
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: Fall Meeting 2005