Effects of asteroid and comet impacts on habitats for lithophytic organisms—A synthesis

available online at http://meteoritics.org 1901 © The Meteoritical Society, 2005. Printed in USA. Effects of asteroid and comet impacts on habitats for lithophytic organisms—A synthesis Charles S. COCKELL1*, Pascal LEE2, Paul BROADY3, Darlene S. S. LIM2, Gordon R. OSINSKI4, John PARNELL5, Christian KOEBERL6, Lauri PESONEN7, and Johanna SALMINEN7 1Planetary and Space Sciences Research Institute, Open University, Milton Keynes. MK7 6AA, UK 2NASA Ames Research Center, Moffett Field, California 94035–1000, USA 3School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand 4Canadian Space Agency, 6767 Route de l’Aeroport, Saint-Hubert, Quebec, J3Y 8Y9, Canada 5Department of Geology, University of Aberdeen, Aberdeen, AB24 3UE, UK 6Department of Geological Sciences, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria 7Division of Geophysics, Department of Physical Sciences, University of Helsinki, P.O. Box 64, 00014 University of Helsinki, Finland *Corresponding author. E-mail: [email protected] (Received 04 April 2005; revision accepted 03 August 2005) Abstract–Asteroid and comet impacts can have a profound influence on the habitats available for lithophytic microorganisms. Using evidence from the Haughton impact structure, Nunavut, Canadian High Arctic, we describe the role of impacts in influencing the nature of the lithophytic ecological niche. Impact-induced increases in rock porosity and fracturing can result in the formation of cryptoendolithic habitats. In some cases and depending upon the target material, an increase in rock translucence can yield new habitats for photosynthetic cryptoendoliths. Chasmoendolithic habitats are associated with cracks and cavities connected to the surface of the rock and are commonly increased in abundance as a result of impact bulking. Chasmoendolithic habitats require less specific geological conditions than are required for cryptoendolithic habitats, and their formation is likely to be common to most impact events. Impact events are unlikely to have an influence on epilithic and hypolithic habitats except in rare cases, where, for example, the formation of impact glasses might yield new hypolithic habitats. We present a synthetic understanding of the influence of asteroid and comet impacts on the availability and characteristics of rocky habitats for microorganisms.Asteroid and comet impacts can have a profound influence on the habitats available for lithophytic microorganisms. Using evidence from the Haughton impact structure, Nunavut, Canadian High Arctic, we describe the role of impacts in influencing the nature of the lithophytic ecological niche. Impact-induced increases in rock porosity and fracturing can result in the formation of cryptoendolithic habitats. In some cases and depending upon the target material, an increase in rock translucence can yield new habitats for photosynthetic cryptoendoliths. Chasmoendolithic habitats are associated with cracks and cavities connected to the surface of the rock and are commonly increased in abundance as a result of impact bulking. Chasmoendolithic habitats require less specific geological conditions than are required for cryptoendolithic habitats, and their formation is likely to be common to most impact events. Impact events are unlikely to have an influence on epilithic and hypolithic habitats except in rare cases, where, for example, the formation of impact glasses might yield new hypolithic habitats. We present a synthetic understanding of the influence of asteroid and comet impacts on the availability and characteristics of rocky habitats for microorganisms.