TY  - JOUR
A1  - Cockell, Charles S.
A1  - Voytek, Mary A.
A1  - Gronstal, Aaron L.
A1  - Finster, Kai
A1  - Kirshtein, Julie D.
A1  - Howard, Kieren
A1  - Reitner, Joachim
A1  - Gohn, Gregory S.
A1  - Sanford, Ward E.
A1  - Horton, J. Wright
A1  - Kallmeyer, Jens
A1  - Kelly, Laura
A1  - Powars, David S.
T1  - Impact disruption and recovery of the deep subsurface biosphere
JF  - Astrobiology
N2  - 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 similar to 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 rnicrobiota 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 similar to 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.
KW  - Asteroid
KW  - Impacts
KW  - Subsurface biosphere
KW  - Subterranean environment
KW  - Geobiology
Y1  - 2012
U6  - https://doi.org/10.1089/ast.2011.0722
SN  - 1531-1074
VL  - 12
IS  - 3
SP  - 231
EP  - 246
PB  - Liebert
CY  - New Rochelle
ER  -