| Popis: |
Fifty-four 2D seismic profiles and 13 boreholes were used to describe pre-impact and post-impact deposits in the Yucatan Shelf. Previous work has identified a pre-impact basin in the northwest portion of the Chicxulub structure. The geometry of seismic reflectors associated with the Mesozoic Era shows that this pre-impact depression, here named Yucatan Trough, extends from the southern part of the Yucatan Peninsula to the northern face of the Campeche Escarpment. Stratigraphic data from boreholes of the Yucatan Platform suggest that the main sedimentary fills of the Yucatan Trough are a thin series of Upper Jurassic-Lower Cretaceous red beds, followed by the evaporite-dominated Lower Cretaceous and the carbonate-dominated Upper Cretaceous sedimentary successions. The mapping of the Cretaceous-Paleogene (K/Pg) deposits allowed us to observe the morphology of the Yucatan Shelf by the time of the Chicxulub impact event. The two-way seismic time K/Pg deposits map in conjunction with the free-air gravity anomaly map of the northern Yucatan Block reveals that, before the impact, the carbonate platform was divided into two blocks by a ~ 95–205 km wide and ~ 470-km long trough-shaped depression, probably a rift-basin with a north-south orientation, in which the central structure of Chicxulub impact crater is contained. The seismic reflectors overlying the top of the K/Pg deposits show that, during the Cenozoic Era, both the Yucatan Trough and impact basin were filled by progradational sequences which flattened the surface completely until the current block of the Yucatan Platform was configured. |
Full Text from ScienceDirect