40Ar/ 39Ar age of the Kaiparowits Formation, southern Utah, and correlation of contemporaneous Campanian strata and vertebrate faunas along the margin of the Western Interior Basin
Abstract
Laser-fusion 40Ar/ 39Ar analysis of four bentonite horizons produces the first absolute ages for the 860-m-thick Kaiparowits Formation and resolves previous age uncertainty caused by ambiguous biostratigraphy. A late Campanian (Judithian) age of ca. 76.1-74.0 Ma is determined, resulting in a high-resolution temporal framework for the richly fossiliferous formation. Detailed stratigraphic correlation reveals that the Kaiparowits Formation is contemporaneous with many of the most important vertebrate fossil-bearing formations in the Western Interior Basin, and with other well-studied strata across Utah and southeastern Wyoming, including portions of the Book Cliffs sequence. The Judithian age determination and correlations for the Kaiparowits Formation presented here provide a new chronological basis for addressing questions relating to mammal biostratigraphy, vertebrate evolution, biodiversity and paleobiogeography (e.g., dinosaur provincialism) in the Cretaceous Western Interior Basin.
- Publication:
-
Cretaceous Research
- Pub Date:
- 2005
- DOI:
- 10.1016/j.cretres.2005.01.002
- Bibcode:
- 2005CrRes..26..307R
- Keywords:
-
- Cretaceous;
- Geochronology;
- Stratigraphy;
- North America;
- Vertebrata