PERMIAN-TRIASSIC SEQUENCE IN NORTHWEST UTAH

The Permian-Triassic interval in part of the eastern Great Basin can be defined more precisely than previously, because conodont faunas have been recognized in the Gerster and overlying Dinwoody Formations. An Early Triassic fauna, including Anchignathodus typicalis, has been obtained from the lowest Dinwoody beds. The underlying Gerster beds contain a Neogondolella postserrata fauna, which can be correlated with that of the Amarassian Lamar Limestone in West Texas. Thus this confirms a late Guadalupian age for the youngest Permian strata known in the eastern Great Basin. This correlation also permits a more precise definition of the magnitude of the Permian-Triassic unconformity for at least a part of the Great Basin than has been available until now. © 1977 Geological Society of America.