Three-dimensional gravity modeling of Chicxulub Crater structure, constrained with marine seismic data and land boreholes

Abstract

We present a three-dimensional multi-formation inversion model for the gravity anomaly over Chicxulub Crater, constrained with available marine seismic data and land boreholes. We used eight formations or rock units as initial model, corresponding to: sea water, Paleogene sediments, suevitic and bunte breccias, melt, Cretaceous carbonates and upper and lower crust. The model response fits 91.5% of the gravity data. Bottom topography and thickness plots for every formation are shown, as well as vertical cross-sections for the 3-D model. The resulting 3-D model shows slightly circular features at crater bottom topography, which are more prominent at the base of the breccias unit. These features are interpreted as normal faults oriented towards the crater center, revealing a circular graben-like structure, whose gravity response correlates with the rings observed in the horizontal gravity gradient. At the center of the model is the central uplift of upper and lower crust, with the top covered by an irregular melt layer. Top of the upper crust shows two protuberances that can be correlated with the two positive peaks of the gravity anomaly. Top of Cretaceous seems to influence most of the response to the gravity anomaly, associated with a high density contrast.