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Re: Double impact at K-T boundary ?
In the previous decade, the Pacific Ocean was also proposed as a possible
locale for additional boundary-time impact(s).
Kerr, R.A. 1996. A piece of the dinosaur killer found? Science 271:1806.
Kyte, F.T. 1998. A meteorite from the Cretaceous/Tertiary boundary. Nature 396:
Robin, E., L. Froget, C. Jehanno, and R. Rocchia. 1993. Evidence for a K/T
impact in the Pacific Ocean. Nature 363:615-617.
---------- Original Message ----------
From: Gautam Majumdar <firstname.lastname@example.org>
Subject: Double impact at K-T boundary ?
Date: Fri, 27 Aug 2010 21:55:46 +0100
Geology 2010; 38: 835-38 doi: 10.1130/G31034.1
The end-Cretaceous mass extinction has been attributed by most to a single
asteroid impact at Chicxulub on the Yucatán Peninsula, Mexico. The discovery
of a second smaller crater with a similar age at Boltysh in the Ukraine has
raised the possibility that a shower of asteroids or comets impacted Earth
close to the Cretaceous-Paleogene (K-Pg) boundary. Here we present
palynological and delta-13C evidence from crater-fill sediments in the . Our
analyses demonstrate that a post-impact flora, formed on the ejecta layer, was
in turn devastated by the K-Pg event. The sequence of floral recovery from the
K-Pg event is directly comparable with that in middle North America. We
conclude that the Boltysh crater predated Chicxulub by ~ 2-5 k.y., a time
scale that constrains the likely origin of the bodies that formed the two
known K-Pg craters.
Interestingly a double impact was proposed by Wolfe in 1991
Palaeobotanical evidence for June 'impact winter' at the Cretaceous/Tertiary
boundary, Nature 1991; 352: 420-2
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