Impact disruption and recovery of the deep subsurface biosphere

By: , and 



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.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Impact disruption and recovery of the deep subsurface biosphere
Series title Astrobiology
DOI 10.1089/ast.2011.0722
Volume 12
Issue 3
Year Published 2012
Language English
Publisher Mary Ann Liebert, Inc.
Contributing office(s) National Research Program - Eastern Branch
Description 16 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Astrobiology
First page 231
Last page 246