Deep crustal structure of the Chicxulub impact crater

Citation
Gl. Christeson et al., Deep crustal structure of the Chicxulub impact crater, J GEO R-SOL, 106(B10), 2001, pp. 21751-21769
Citations number
37
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Earth Sciences
Journal title
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
ISSN journal
2169-9313 → ACNP
Volume
106
Issue
B10
Year of publication
2001
Pages
21751 - 21769
Database
ISI
SICI code
0148-0227(20011010)106:B10<21751:DCSOTC>2.0.ZU;2-0
Abstract
We present the results of a wide-angle seismic survey conducted over the Ch icxulub. impact crater. Profile Chicx-A/A1 is a chord across the offshore p ortion of the crater, and Chicx-B/F is an onshore-offshore profile through the center of the crater. We use travel times recorded by 32 ocean bottom s eismograph and 19 land-based receivers to model the crustal structure of th e crater. The primary feature in the shallow velocity structure is a low-ve locity Tertiary basin, the edge of which correlates with a steep gravity gr adient in some regions of our survey. Directly beneath the Tertiary basin a t the center of the crater is a region of relatively low velocities and den sities that is interpreted as a unit of melt rocks (either suevite breccias with isolated melt pods or suevite breccias overlying a coherent melt shee t). This unit has a thickness of similar to1 km and a diameter of similar t o 100 km. Central uplift with a diameter of 40-60 km is observed on Chicx-B /F. A lower limit on the vertical extent of uplift is 9 km. Shallow basemen t is also observed along the northwest portion of Chicx-B/F, associated wit h a prominent northwest trending high in the gravity field. Superimposed on a regional trend is Moho uplift of similar to1 km near the center, of the Chicx-A/A1 profile, with adjacent Moho deepening of similar to1.25-1.5 km. The Moho topography may be related to deformation. processes associated wit h the formation of the outer ring or to the excavation and collapse of the transient cavity.