Deep Drilling into the Chesapeake Bay Impact Structure
G. S. Gohn,1*
C. Koeberl,2
K. G. Miller,3
W. U. Reimold,4
J. V. Browning,3
C. S. Cockell,5
J. W. Horton, Jr.,1
T. Kenkmann,4
A. A. Kulpecz,3
D. S. Powars,1
W. E. Sanford,1
M. A. Voytek1
Samples from a 1.76-kilometer-deep corehole drilled near the
center of the late Eocene Chesapeake Bay impact structure (Virginia,
USA) reveal its geologic, hydrologic, and biologic history.
We conducted stratigraphic and petrologic analyses of the cores
to elucidate the timing and results of impact-melt creation
and distribution, transient-cavity collapse, and ocean-water
resurge. Comparison of post-impact sedimentary sequences inside
and outside the structure indicates that compaction of the crater
fill influenced long-term sedimentation patterns in the mid-Atlantic
region. Salty connate water of the target remains in the crater
fill today, where it poses a potential threat to the regional
groundwater resource. Observed depth variations in microbial
abundance indicate a complex history of impact-related thermal
sterilization and habitat modification, and subsequent post-impact
repopulation.
2 Department of Lithospheric Research, Center for Earth Sciences, University of Vienna, Althanstrasse 14, Vienna A-1090, Austria.
3 Department of Geological Sciences, Rutgers University, 610 Taylor Road, Piscataway, NJ08854, USA.
4 Museum of Natural History (Mineralogy), Humboldt-University Berlin, Invalidenstrasse 43, Berlin 10115, Germany.
5 Centre for Earth, Planetary, Space, and Astronomical Research, Open University, Milton Keynes MK7 6AA, UK.
* To whom correspondence should be addressed. E-mail: ggohn{at}usgs.gov
