Shock melting of the Canyon Diablo Impactor: Constraints from nickel-59 contents and numerical modeling

Two main types of material survive from the Canyon Diablo impactor, which p roduced Meteor Crater in Arizona: iron meteorites, which did not melt durin g the impact; and spheroids, which did. Ultrasensitive measurements using a ccelerator mass spectrometry show that the meteorites contain about seven t imes as much nickel-59 as the spheroids. Lower average nickel-59 contents i n the spheroids indicate that they typically came from 0.5 to 1 meter deepe r in the impactor than did the meteorites. Numerical modeling for an impact velocity of 20 kilometers per second shows that a shell 1.5 to 2 meters th ick, corresponding to 16 percent of the projectile volume, remained solid o n the rear surface; that most of the projectile melted; and that little, if any, vaporized.