Resumo

POVEDA, A  e  CORDERO, G. Chicxulubites: a New Class of Meteorites?. Geofís. Intl [online]. 2008, vol.47, n.3, pp.167-172. ISSN 2954-436X.

It is well known that asteroidal impacts on the Moon and Mars have ejected a large number of fragments that, after traveling in the inner planetary system for thousands or millions of years, occasionally fall on Earth and are recovered as meteorites. It is of interest, therefore, to ask the question: what fraction of the mass excavated from the Chicxulub crater was ejected with escape velocities as the result of the 100 million megaton explosion? These fragments, similarly to what happened with lunar and martian ejecta, can fall onto the Moon, as well as back on the Earth as meteorites: Chicxulubites. A 10 km-diameter asteroid, like the one at Chicxulub, could have produced a number of high velocity fragments with a total mass of about one thousandth of the mass of the projectile. From the work of Vickery (1987) on secondary craters on Mercury, the Moon and Mars, we estimated the mass and the diameter of the largest fragments that would have a velocity larger than the Earth's escape velocity. Assuming Dohnanyi's mass frequency distribution, we estimated that the number of fragments with sizes larger than 10 cm and 2 cm is about 4x10¹⁰ and 2x10¹², respectively. We also estimated the expected fraction of these Chicxulubites to the total number of earth-crossing asteroids (ECA's) of similar diameter. We conclude that a number of fragments from the Chicxulub crater have fallen onto the Moon and the Earth after becoming ECAs, and are waiting to be identified as Chicxulubites.

Palavras-chave : Chicxulub; secondary craters; ejected fragments.

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