Dynamic modeling suggests terrace zone asymmetry in the Chicxulub crater is caused by target heterogeneity

Collins, Gareth S. and Morgan, Joanna and Barton, Penny and Christeson, Gail L. and Gulick, Sean and Urrutia, Jaime and Warner, Michael and Wunnemann, Kai (2008) Dynamic modeling suggests terrace zone asymmetry in the Chicxulub crater is caused by target heterogeneity. Earth and Planetary Science Letters, 270 (3-4). 221 - 230. ISSN 0012-821X DOI 10.1016/j.epsl.2008.03.032

[img] PDF
barton2.pdf
Restricted to Registered users only

Download (2MB)
Official URL: http://www.sciencedirect.com/science/article/pii/S...

Abstract

We investigate the cause of terrace zone asymmetry in the Chicxulub impact crater using dynamic models of crater formation. Marine seismic data acquired across the crater show that the geometry of the crater's terrace zone, a series of sedimentary megablocks that slumped into the crater from the crater rim, varies significantly around the offshore half of the crater. The seismic data also reveal that, at the time of impact, both the water depth and sediment thickness varied with azimuth around the impact site. To test whether the observed heterogeneity in the pre-impact target might have affected terrace zone geometry we constructed two end-member models of upper-target structure at Chicxulub, based on the seismic data at different azimuths. One model, representing the northwest sector, had no water layer and a 3-km thick sediment layer; the other model, representing the northeast sector, had a 2-km water layer above a 4-km sediment layer. Numerical models of vertical impacts into these two targets produced final craters that differ substantially in terrace zone geometry, suggesting that the initial water depth and sediment thickness variations affected the structure of the terrace zone at Chicxulub. Moreover, the differences in terrace zone geometry between the two numerical models are consistent with the observed differences in the geometry of the terrace zone at different azimuths around the Chicxulub crater. We conclude that asymmetry in the pre-impact target rocks at Chicxulub is likely to be the primary cause of asymmetry in the terrace zone.

Item Type: Article
Uncontrolled Keywords: 08AREP;
Subjects: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Divisions: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Journal or Publication Title: Earth and Planetary Science Letters
Volume: 270
Page Range: 221 - 230
Identification Number: 10.1016/j.epsl.2008.03.032
Depositing User: Sarah Humbert
Date Deposited: 10 Dec 2011 00:53
Last Modified: 23 Jul 2013 10:03
URI: http://eprints.esc.cam.ac.uk/id/eprint/2272

Actions (login required)

View Item View Item

About cookies