Much of the geologic history of equatorial Pangea in the Late Triassic is recorded in widespread redbed successions. This contribution by Atchley et al. examines one of these alluvial successions (the Late Triassic Chinle Formation) by calibrating sedimentological and pedogenic features to a high-precision geochronology, to assess relations among cyclic alluviation, climate shifts and biological turnover. The resulting age model and associated stratigraphic and paleoclimatic record represents a markedly refined constraint on the character of the Chinle Formation. These data reveal the history of cyclic environmental change and corresponding biotic turnover, and its temporal correlation to the Late Triassic tectonic history and physiographic evolution of western Pangea. As such, the results shed light on the previously undetected balance among life, paleogeography and tectonism within the Late Triassic of the southwestern United States, and may be broadly comparable to other sedimentary and ecologic systems.
A linkage among Pangean tectonism, cyclic alluviation, climate change, and biologic turnover in the Late Triassic: the record from the Chinle Formation, southwestern United States by Stacy C. Atchley, Lee C. Nordt, Stephen I. Dworkin, Jahandar Ramezani, William G. Parker, Sidney R. Ash, and Samuel A. Bowring