Stratigraphy, paleontology and age of the Fruitland and Kirtland Formations (Upper Cretaceous), San Juan Basin, New Mexico

Abstract

---- Campanian-Maastrichtian nonmartne strata of the San Juan Basin pertain to the Fruitland Formation and the Kirtland Formation. The Kirtland consists, in ascending order, of the Bisti, Hunter Wash, Farmington. De-na-zin and Naashoibito Members. The Fruitland is dominantly of deltaic and paludal origin and the Kirtland is of broadly fluvial origin. The Bisti Member is a gas reservoir. The majority of fossil vertebrates are from an interval in the uppermost Fruitland and from the Naashoibito Member. Distinct vertebrate and invertebrate faunas and floras can be distinguished for the Fruitland, pre-Naashoibito Kirtland and Naashoibito. Diverse evidence indicates that the Fruitland is of Judithian (late Campanian) age, the pre-Naashoibito Kirtland is of Edmontonian (early Maastrichtian) age and the Naashoibito is of Lancian (late Maastrichtian) age. There is no large-scale angular unconformity at the base of the Ojo Alamo Sandstone.