Correlation, Age, and Regional Distribution of the Nugget Sandstone and Glen Canyon Group, Utah
Douglas A. Sprinkel, Bart J. Kowallis, and Paul H. Jensen
Utah Geological Survey
The Nugget Sandstone is exposed and has been drilled in the Sevier thrust belt of northern Utah and around the flank of the Uinta Mountains. The Glen Canyon Group, which consists of the Wingate Sandstone/Moenave Formation, Kayenta Formation, and Navajo Sandstone, is exposed and has been drilled on the Colorado Plateau and in the central and southwestern sectors of the Utah Sevier thrust belt. The Nugget Sandstone is not included as a formation of the Glen Canyon Group, and thus two terms are used for similar strata above the Triassic Ankareh-Chinle Formations and below the Middle Jurassic formations throughout Utah. There has been some uncertainty as to the correlation of the Nugget Sandstone with either all or part of the Glen Canyon Group, especially in the eastern Uinta Mountains, the Uinta Basin, and parts of the Sevier thrust belt in central and southwestern Utah. Aetosaur and dinosaur tracks preserved in the Nugget Sandstone in the eastern Uinta Mountains and in exposures throughout the Glen Canyon Group include similar assemblages in approximately the same stratigraphic positions, strongly suggesting they are correlative. In addition, well log interpretation suggests that the Nugget Sandstone correlates with the entire Glen Canyon Group and that the Kayenta Formation either pinches out or transitions from fluvial to eolian deposition under the Uinta Basin and along the thrust belt in the Provo salient and southward to the Mineral Mountains area. Therefore, the term Nugget Sandstone should be used where the Kayenta Formation is not present or recognized and the section consists entirely of eolianite. Glen Canyon Group should be used where the Kayenta is recognized. The age of the Nugget Sandstone is Late Triassic to Early Jurassic, which is similar to the Glen Canyon Group, and places the Triassic-Jurassic boundary within the Nugget Sandstone and not at its base as previously thought.
AAPG Search and Discovery Article #90169©2013 AAPG Rocky Mountain Section 62nd Annual Meeting, Salt Lake City, Utah, September 22-24, 2013