Transcript Document
The Department of Geography Speaker Series presents… Microbes, Volcanoes, and Evidence of Early Life on Earth Neil Banerjee Department of Earth Science University of Western Ontario [email protected] Over the past decade, studies of volcanic glass from modern oceanic crust have demonstrated the importance of endolithic microorganisms in the alteration process. Microbial alteration features are ubiquitous within the oceanic crust, having been discovered in basalts of all ages, wherever fresh glass is preserved. More recent work in ophiolites and greenstone belts has extended the evidence for microbial alteration of oceanic basalts beyond the record preserved in the modern oceans back to the Archean. For example, biosignatures have been well documented in the formerly glassy rims of ~3.2 to ~3.5billion year-old pillow lavas from South Africa and Western Australia. We have recently discovered similar biosignatures in hyaloclastites sampled from the ~2.7 Ga Abitibi Greenstone Belt north of Kirkland Lake, Ontario. Based on the similarity to textures observed in recent glassy pillow basalts, we interpret these structures to represent ancient mineralized traces of microbial activity in these samples. Subaqueous volcanic rocks preserved in greenstone belts worldwide are a new geological setting in the search for early life on Earth. This has important implications for the exploration for life on Mars and in our solar system. It shows that robust biosignatures of a presently observable, global microbial process can be preserved for billions of years. Also, it suggests that microbial life had already colonized volcanic rocks on Earth at a time when liquid water may have been present at or near the surface of Mars. Since basalts are likely to be returned by any extra-terrestrial sample return mission, detailed studies of microbial alteration signatures preserved in aqueously altered basalts provide a useful Earth analogue for studies of possible extraterrestrial microbial habitats Friday November 30th @ 3:00PM Social Science Centre, Room 2333 Serving Complimentary Fair Trade Coffee, refreshments and light snacks. Please feel free to bring you reusable coffee mugs. For more information or to be notified of upcoming presentations, please contact Dr. Katrina Moser ([email protected])