[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
The original paper with abstract
On Thursday 24 January 2008 00:32:21 Janet m vandenburgh wrote:
> Seismic images show dinosaur-killing meteor made bigger splash The most
> detailed three-dimensional seismic images yet of the Chicxulub crater, a
> mostly submerged and buried impact crater on the Mexico coast, may modify a
> theory explaining the extinction of 70 percent of life on Earth 65 million
> years ago.
> ... According to Sean Gulick, a research scientist at the Institute for
> Geophysics at The University of Texas at Austin's Jackson School of
> Geosciences and principal investigator for the project,...
> CyberDefender has scanned this email for potential threats.
> Version 2.0 / Build 3.03.16.00
> Get free PC security at www.cyberdefender.com
Published online: 13 January 2008 | doi:10.1038/ngeo103
Importance of pre-impact crustal structure for the asymmetry of the Chicxulub
Sean P. S. Gulick1, Penny J. Barton2, Gail L. Christeson1, Joanna V. Morgan3,
Matthew McDonald1,6, Keren Mendoza-Cervantes4, Zulmacristina F. Pearson5,7,
Anusha Surendra2, Jaime Urrutia-Fucugauchi4, Peggy M. Vermeesch3,7 & Mike R.
Impact craters are observed on the surfaces of all rocky planets and
satellites in our Solar System1; some impacts on Earth, such as the
Cretaceous/Tertiary one that formed the Chicxulub impact crater2, 3, have
been implicated in mass extinctions4, 5, 6, 7, 8, 9, 10, 11, 12. The
direction and angle of the impactâor its trajectoryâis an important
determinant of the severity of the consequent environmental damage, both in
the downrange direction (direction bolide travels) and in the amount of
material that enters the plume of material vaporized on impact2, 13, 14, 15.
The trajectory of the Chicxulub impact has previously been inferred largely
from asymmetries in the gravity anomalies over the crater2, 3. Here, we use
seismic data to image the Chicxulub crater in three dimensions and
demonstrate that the strong asymmetry of its subsurface correlates with
significant pre-existing undulations on the end-Cretaceous continental shelf
that was the site of this impact. These results suggest that for rocky
planets, geological and geomorphological heterogeneities at the target site
may play an important role in determining impact crater structure, in
addition to impact trajectories. In those cases where heterogeneous targets
are inferred, deciphering impact trajectories from final crater geometries
alone may be difficult and require further data such as the distribution of