First high-precision U-Pb CA-ID-TIMS age for the Battle Formation (Upper Cretaceous), Red Deer River valley, Alberta, Canada: implications for ages, correlations, and dinosaur biostratigraphy of the Scollard, Frenchman, and Hell Creek formations

The Battle Formation (BFm) is a widespread Upper Cretaceous marker horizon in western Canada that records a time of low sediment input and marks the boundary between the Edmontonian and Lancian land-vertebrate ages. Here, we present the first high-precision U-Pb CA-ID-TIMS age of 66.936 +/- 0.047/0.060/0.140 Ma for the Battle bentonite, an altered vitric ash in the upper portion of the BFm at Knudsen's Farm in the Red Deer River valley of Alberta. This age supersedes those previously reported, confirms that rates of sediment accumulation for the formation were very low (similar to 1.40 cm/ka), and allows us to interpolate an age range of similar to 66.88-67.20 Ma for the BFm. Our data also provide a maximum age of similar to 66.88 Ma for the base of the overlying Scollard Formation, a dinosaur-rich unit. We combine our age data with calibrated magneto- and palynostratigraphic data to assess chronostratigraphic correlations among the Scollard Formation of Alberta, the Frenchman Formation of Saskatchewan, and the Hell Creek Formation in eastern Montana. Whereas the combined data support previous interpretations that equate the age ranges of the Scollard Formation, Frenchman Formation, and the upper one third of the Hell Creek Formation in eastern Montana, they also indicate that all of the lower one third (L3) and part of the middle one third (M3) of the Hell Creek Formation in Montana are chronostratigraphically equivalent to all or part of the sub-BFm unconformity and the BFm in Alberta. Accordingly, a minimum age of similar to 67.20 Ma is assessed for the base of the Hell Creek Formation in its type area.