Abstract

Using Gauss's theorem, we estimated the mass deficiency of the Chicxulub impact structure (Yucatan, Mexico) from its gravity anomaly. The mass deficiency obtained from the residual gravity anomaly map ranges between 1.06X10 16 and 1.67X10 16 kg. Because the gravity anomaly has approximately radial symmetry, we also estimated the mass deficiency from selected profiles. In this way, we obtained slightly lower mass deficiencies (6.16X10 15 to 1.35X10 16 kg). The central gravity high, which is supposed to be associated with the central structural high, has a mean excess mass of 1.93X10 14 kg. By assuming a mean density contrast of 100 kg/m 3 between the country rock and the sedimentary and brecciated rocks, we estimated the equivalent total mass (1.60X10 17 to 4.34X10 17 kg) and volume (6.16X10 13 to 1.67X10 14 m 3 ) of breccias and sedimentary rocks responsible for the gravity anomaly. These figures represent lower bounds on the mass and volume ejected from the impact crater. They represent estimates made from geophysical principles and data, and compare well with independent estimates based on other principles such as scaling relations. According to actual estimations of the sulfur dioxide mass generated by the Cretaceous-Tertiary impact and our results, only a small fraction (about 1%) of the anhydrite in the target strata was vaporized.

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