Using Grain-Size to Interpret Cretaceous-Paleogene Extinction Event
Bralower, T., L. Eccles, J. Kutz, T. Yancey, J. Schueth, M. Arthur,
and D. Bice, 2010, Grain size of Cretaceous-Paleogene boundary
sediments from Chicxulub to the open ocean: Implications for
interpretation of the mass extinction event. Geology, v. 38,
no. 3, p. 199-202; DOI: 10.1130/G30513.1
http://geology.geoscienceworld.org/cgi/content/abstract/38/3/199
Grain size of Cretaceous-Paleogene boundary sediments from
Chicxulub to the open ocean: Implications for interpretation
of the mass extinction event March 2010 Geology and GSA
Today Highlights.
http://www.physorg.com/wire-news/29077449/march-2010-geology-and-gsa-today-highlights.html
“The causes of the mass extinction of 75% of marine and 50%
of terrestrial species (including the dinosaurs) at the
Cretaceous-Tertiary boundary, 65 million years ago, has been
the subject of raging debate. The majority of scientists support
the theory that the impact of an asteroid on the Yucatan
Peninsula (Mexico) was the trigger of the extinctions. The most
potent evidence for this theory is a layer of rock containing
telltale signs of impact, including melt droplets and shocked
mineral grains that can be traced from the Yucatan around the
world. Basing their research on fossils in rocks around the
Gulf of Mexico, a group of scientists have recently proposed
that the Yucatan impact preceded the mass extinction by 300
thousand years, and that the extinction was caused by a
massive volcanic event in India. The current study by Bralower
et al., however, leads to a different conclusion through the
analysis of sediment particle size in Cretaceous-Tertiary
boundary samples to determine the origin of fossil shells. The
data demonstrate that fossils in Cretaceous-Tertiary boundary
rocks around the Gulf of Mexico region are eroded from
underlying layers by a tsunami at the impact event. Thus
they rule out the correlation of the mass extinction event with
Indian volcanism and conclusively support the connection with
the Yucatan impact.”
Yours,
Paul H.
