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Kai Finster

Impact disruption and recovery of the deep subsurface biosphere

Publikation: Bidrag til tidsskrift/Konferencebidrag i tidsskrift /Bidrag til avisTidsskriftartikelForskningpeer review

  • Charles S. Cockell, The Open University, Milton Keynes, Storbritannien
  • Mary A. Voytek, U.S. Geological Survey, Reston, Virginia, USA
  • Aaaron L Gronstal, The Open University, Milton Keynes, Storbritannien
  • Kai Finster
  • Julie D Kirshtein, U.S. Geological Survey, Reston, Virginia, USA
  • Kieren Howard, Meteoritics and Cosmic Mineralogy, Natural History Museum, London, Storbritannien
  • Joachim Reitner, Centre of Geosciences, University of Göttingen, Tyskland
  • Gregory S. Gohn, U.S. Geological Survey, Reston, Virginia, USA
  • Ward E. Sanford, U.S. Geological Survey, Reston, Virginia, USA
  • J. Wright Horton, Jr., U.S. Geological Survey, Reston, Virginia, USA
  • Jens Kallmeyer, Universität Postdam, Golm, Tyskland
  • Laura Kelly, The Open University, Milton Keynes, Storbritannien
  • David S. Powars, U.S. Geological Survey, Reston, Virginia, USA
Although a large fraction of the world's biomass resides in the subsurface, there has been no study of the effects of catastrophic disturbance on the deep biosphere and the rate of its subsequent recovery. We carried out an investigation of the microbiology of a 1.76 km drill core obtained from the 35 million-year-old Chesapeake Bay impact structure, USA, with robust contamination control. Microbial enumerations displayed a logarithmic downward decline, but the different gradient, when compared to previously studied sites, and the scatter of the data are consistent with a microbiota influenced by the geological disturbances caused by the impact. Microbial abundance is low in buried crater-fill, ocean-resurge, and avalanche deposits despite the presence of redox couples for growth. Coupled with the low hydraulic conductivity, the data suggest the microbial community has not yet recovered from the impact 35 million years ago. Microbial enumerations, molecular analysis of microbial enrichment cultures, and geochemical analysis showed recolonization of a deep region of impact-fractured rock that was heated to above the upper temperature limit for life at the time of impact. These results show how, by fracturing subsurface rocks, impacts can extend the depth of the biosphere. This phenomenon would have provided deep refugia for life on the more heavily bombarded early Earth, and it shows that the deeply fractured regions of impact craters are promising targets to study the past and present habitability of Mars. Key Words: Asteroid—Impacts—Subsurface biosphere—Subterranean environment—Geobiology. Astrobiology 12, 231–246.
OriginalsprogEngelsk
TidsskriftAstrobiology
Vol/bind12
Nummer3
ISSN1531-1074
DOI
StatusUdgivet - 2012

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