Lyell Collection
Geological Society, London, Special Publications
Lyell Centre  |   Lyell Collection  |   Subscriptions   |   Geological Society  |   Email alerts  |   Online bookshop  |   Help

Keywords:
Author:
Advanced search>>
This Article
Right arrow Full Text (PDF)
Right arrow References
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Permissions
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Maguire, P. K. H.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation
Geological Society, London, Special Publications; 1998; v. 140; p. 177-193;
DOI: 10.1144/GSL.SP.1998.140.01.13
© 1998 Geological Society of London

Craters and Impactites

Preliminary results from a passive seismic array over the Chicxulub impact structure in Mexico

P. K. H. Maguire1, G. D. Mackenzie1, P. Denton1, A. Trejo2, R. Kind3 & Members*

1 University of Leicester, University Road, Leicester LE1 7RH, UK
2 Universidad Nacional Autonoma de Mexico, Mexico DF, Mexico
3 GeoForschung Zentrum, Potsdam, Germany

A passive, 20-element, short-period (1 Hz) and broadband seismic array was deployed over the Chicxulub impact structure for c. 100 days in early 1996. The principal objective was to study the shear-wave anisotropy associated with the structure; in particular, to determine the presence (or absence) of radial symmetry which will allow comment on the time variance of that anisotropy. A total of 15 teleseismic, 75 regional, and 100 local events were recorded. Preliminary results from studies of the surface-wave dispersion of the local events, and a receiver function analysis of a single teleseismic event are reported here. Thirty local events have been located, a number of which originated from quarries within the array. Analysis of seismo grams from three of these events demonstrates a bimodal distribution; those whose ray-paths cross the outer part of the impact structure show a strong inverse dispersion, whereas those with ray-paths crossing the centre do not. The pattern may be produced by the sedimentary depositional environment, with deeper water sedimentation in the outer part of the post-impact crater basin and shallower water sedimentation over the upraised peak-ring block at the centre. Receiver functions derived for an event originating in Peru are dominated by an efficient mode conversion, simply modelled as a P-S multiple from the base Tertiary boundary. This shows a strong correlation with distance from the centre of the impact structure and implies it has an S-wave radial symmetry. The multiple also has a variable delay probably related to the depth of the conversion boundary. Unfortunately, the Moho conversion occurs at almost exactly the same time as this surface layer sediment multiple, restricting any modelling of Moho topography and its influence on the receiver functions.


* J. Morgan1, M. Warner1, J. Brittan1, H. Macintyre1, E. King2, D. Snyder3, L. Marin4 and G. Suarez4

1 Department of Geology, Imperial College, London, UK

2 British Antarctic Survey, Cambridge, UK

3 BIRPS, Bullard Laboratories, University of Cambridge, Cambridge, UK

4 Universidad Nacional Autonoma de Mexico, Mexico DF, Mexico