The “Judith River−Belly River problem” revisited (Montana-Alberta-Saskatchewan): New perspectives on the correlation of Campanian dinosaur-bearing strata based on a revised stratigraphic model updated with CA-ID-TIMS U-Pb geochronology

A revised stratigraphic model, calibrated with U-Pb zircon geochronology, resolves the long-standing 'Judith River−Belly River problem' by correlating the Judith River Formation in Montana with the Foremost, Oldman, and Dinosaur Park Formations (Belly River Group) in Canada. The study identifies a chronostratigraphically significant discontinuity—dubbed the 'Judith River−Belly River discontinuity'—that marks a major pulse of accommodation and the onset of the Bearpaw transgression at approximately 76.3 million years ago (Ma). This discontinuity, traceable from Montana to Dinosaur Provincial Park, parallels the Eagle/Milk River shoulder, confirming its regional significance. The findings advance understanding of alluvial depositional systems in a foreland basin setting and provide a framework for refining regional stratigraphic correlations.

Rogers, R. R., Eberth, D. A., & Ramezani, J. (2023). The “Judith River−Belly River problem” revisited (Montana-Alberta-Saskatchewan): New perspectives on the correlation of Campanian dinosaur-bearing strata based on a revised stratigraphic model updated with CA-ID-TIMS U-Pb geochronology. Geological Society of America Bulletin. https://doi.org/10.1130/b36999.1