title: Coeval 40Ar/39Ar Ages of 65.0 Million Years Ago from Chicxulub Crater Melt Rock and Cretaceous-Tertiary Boundary Tektites.
abstract: (40)Ar/(39)Ar dating of drill core samples of a glassy melt rock recovered from beneath a massive impact breccia contained within the 180-kilometer subsurface Chicxulub crater in Yucatán, Mexico, has yielded well-behaved incremental heating spectra with a mean plateau age of 64.98 +/- 0.05 million years ago (Ma). The glassy melt rock of andesitic composition was obtained from core 9 (1390 to 1393 meters) in the Chicxulub 1 well. The age of the melt rock is virtually indistinguishable from (40)Ar/(39)Ar ages obtained on tektite glass from Beloc, Haiti, and Arroyo el Mimbral, northeastern Mexico, of 65.01 +/- 0.08 Ma (mean plateau age for Beloc) and 65.07 +/- 0.10 Ma (mean total fusion age for both sites). The (40)Ar/(39)Ar ages, in conjunction with geochemical and petrological similarities, strengthen the recent suggestion that the Chicxulub structure is the source for the Haitian and Mexican tektites and is a viable candidate for the Cretaceous-Tertiary boundary impact site.
authors.forename: C C
authors.initials: CC
authors.lastname: Swisher
authors.forename: J M
authors.initials: JM
authors.lastname: Grajales-Nishimura
authors.forename: A
authors.initials: A
authors.lastname: Montanari
authors.forename: S V
authors.initials: SV
authors.lastname: Margolis
authors.forename: P
authors.initials: P
authors.lastname: Claeys
authors.forename: W
authors.initials: W
authors.lastname: Alvarez
authors.forename: P
authors.initials: P
authors.lastname: Renne
authors.forename: E
authors.initials: E
authors.lastname: Cedillo-Pardoa
authors.forename: F J
authors.initials: FJ
authors.lastname: Maurrasse
authors.forename: G H
authors.initials: GH
authors.lastname: Curtis
authors.forename: J
authors.initials: J
authors.lastname: Smit
authors.forename: M O
authors.initials: MO
authors.lastname: McWilliams