Canadian Journal of Earth Sciences 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 Journal: Canadian Journal of Earth Sciences Manuscript ID cjes-2018-0098.R2 Manuscript Type: Article Date Submitted by the 05-Dec-2018 Author: Complete List of Authors: Eberth, David;Draft Royal Tyrrell Museum of Palaeontology, Kamo, Sandra; University of Toronto, Earth Sciences Battle Formation, U-Pb dating, Dinosaurs, Cretaceous, Hell Creek Keyword: Formation Is the invited manuscript for consideration in a Special Not applicable (regular submission) Issue? : https://mc06.manuscriptcentral.com/cjes-pubs Page 1 of 38 Canadian Journal of Earth Sciences 1 1 First high-precision U-Pb CA-ID-TIMS age for the Battle Formation (Upper 2 Cretaceous), Red Deer River valley, Alberta, Canada: implications for ages, 3 correlations, and dinosaur biostratigraphy of the Scollard, Frenchman, and 4 Hell Creek formations 5 6 7 8 David A. Eberth* and Sandra L. Kamo** 9 10 11 12 13 *Royal Tyrrell Museum of Palaeontology 14 Box 7500 15 Drumheller, Alberta T0J0Y0 16 [email protected] 17 18 **Jack Satterly Geochronology Laboratory 19 Department of Earth Sciences 20 UniversityDraft of Toronto 21 22 Russell St. 22 Toronto, ON, M5S 3B1 23 [email protected] 24 25 https://mc06.manuscriptcentral.com/cjes-pubs Canadian Journal of Earth Sciences Page 2 of 38 2 26 Abstract 27 The Battle Formation (BFm) is a widespread Upper Cretaceous marker horizon in 28 western Canada that records a time of low sediment-input and marks the boundary between the 29 Edmontonian and Lancian land-vertebrate ages. Here, we present the first high-precision U-Pb 30 CA-ID-TIMS age of 66.936 ± 0.047/0.060/0.140 Ma for the Battle bentonite, an altered vitric 31 ash in the upper portion of the BFm at Knudsen’s Farm in the Red Deer River valley of Alberta. 32 This age supersedes those previously reported, confirms that rates of sediment accumulation for 33 the formation were very low (~1.40 cm/ka), and allows us to interpolate an age range of ~66.88– 34 67.20 Ma for the BFm. Our data also provide a maximum age of ~66.88 Ma for the base of the 35 overlying Scollard Formation, a dinosaur-rich unit. We combine our age data with calibrated 36 magneto- and palynostratigraphic data toDraft assess chronostratigraphic correlations among the 37 Scollard Formation (K-ScF) of Alberta, the Frenchman Formation (FFm) of Saskatchewan, and 38 the Hell Creek Formation (HCF) in eastern Montana. Whereas the combined data support 39 previous interpretations that equate the age ranges of the K-ScF, FFm, and the upper one-third of 40 the HCF in eastern Montana, they also indicate that all of the lower one-third (L3) and part of the 41 middle one-third (M3) of the HCF in Montana are chronostratigraphically equivalent to all or 42 part of the sub-BFm unconformity and the BFm in Alberta. Accordingly, a minimum age of 43 ~67.20 Ma is assessed for the base of the Hell Creek Formation in its type area. 44 45 Keywords: Battle Formation, Hell Creek Formation, U-Pb dating, dinosaurs, Cretaceous, 46 Maastrichtian https://mc06.manuscriptcentral.com/cjes-pubs Page 3 of 38 Canadian Journal of Earth Sciences 3 47 Introduction 48 The Upper Cretaceous Battle Formation (BFm) in western Canada is a distinctive and 49 widespread kaolinitic to bentonitic marker horizon, typically less than 10 m thick, that has been 50 employed widely since the 1930s in stratigraphic and paleoenvironmental studies of the Western 51 Canada Sedimentary Basin (Sanderson 1931; Furnival 1942; Elliott 1960; Irish and Havard 52 1968; Irish 1970; Lerbekmo 1985; Binda 1992; Lerbekmo and Braman 2002; Hathway et al. 53 2011; Eberth and Braman 2012). It records a time of unusually cool temperatures, intense 54 volcanism, and low sediment-input in the basin (Eberth and Braman 2012), and its top marks the 55 conventional boundary between the Edmontonian (below) and Lancian (above) land-vertebrate 56 ages (Fowler 2017). Because of its broad stratigraphic utility, easy identification in both outcrop 57 and geophysical logs, and its rich volcanicDraft content, the BFm was one of the first Cretaceous 58 deposits in western Canada to be dated radioisotopically (Folinsbee et al. 1961; Baadsgaard 59 [unpublished age and data reported in Obradovich 1993]; Baadsgaard [unpublished age and data 60 reported in Lerbekmo 2009]). Published dates for the unit were originally limited to K-Ar 61 analyses with large calculated errors (± 1.6–5.0%, 2σ). For example, Folinsbee et al. (1961) 62 reported K-Ar dates of 65, 66, 66, 66, and 68 Ma for five samples collected near Strawberry 63 Creek and stated: “Assumed deviation in dates is 5%.” 64 More refined ages for the BFm were calculated by Baadsgaard (reported in Obradovich 65 1993 and Lerbekmo 2009), but analytical data were not included, thus compromising the utility 66 of the results (although see Fowler’s 2017 recalibration of Obradovich 1993). For example, 67 Baadsgaard obtained an 40Ar/39Ar age of 66.8 ± 1.1 Ma (95% confidence interval) for sample 68 AK-476 from Strawberry Creek (presented in Obradovich 1993, table 1) and later calculated a 69 U-Pb age of 66.5 ± 0.2 Ma for the same sample (presented by Lerbekmo 2009). https://mc06.manuscriptcentral.com/cjes-pubs Canadian Journal of Earth Sciences Page 4 of 38 4 70 To our knowledge no subsequent ages have been reported from the BFm. Accordingly, 71 these low-precision and undocumented results continue to be cited (e.g., Glass 1990; Hamblin 72 2004; Eberth and Braman 2012; Eberth et al. 2013; Fowler 2017), thus limiting our 73 understanding of (1) an accurate age for the BFm, (2) rates of sediment accumulation for this and 74 other stratigraphically associated units, (3) the chronostratigraphy of a variety of climatic and 75 biostratigraphic events in this portion of the western Canadian stratigraphic section (cf. Wu et al. 76 2007; Eberth and Braman 2012; Eberth et al. 2013), and (4) how the BFm correlates with non- 77 marine units within and beyond the basin (cf. Fowler 2017). 78 To improve our understanding of the depositional timing and duration of the BFm, we 79 dated a bentonite (here referred to as the Battle bentonite) from the upper portion of the unit 80 using U-Pb isotope dilution thermal ionizationDraft mass spectrometry on chemically abraded zircon 81 crystals (U-Pb CA-ID-TIMS; Mattinson 2005). Currently, the U-Pb CA-ID-TIMS technique is 82 the most accurate and precise means of dating geologic events in this and other parts of the 83 geologic column. The age of 66.936 ± 0.047/0.060/0.140 Ma for the Battle bentonite that we 84 present here is of high-precision and is well documented, and thus supersedes all previous age 85 interpretations for the formation. In turn, this high-precision age allows us to assess some 86 chrono- and biostratigraphic interpretations for the Maastrichtian portion of the Cretaceous 87 section in western Canada and Montana. 88 89 Location 90 We collected Battle bentonite samples from the Knudsen’s Farm locality (N51.90110 91 W113.01262), 7 km north of Tolman Bridge (Highway 585) along the west side of the Red Deer 92 River valley (Fig. 1). Our attempts to collect samples from the original Strawberry Creek locality https://mc06.manuscriptcentral.com/cjes-pubs Page 5 of 38 Canadian Journal of Earth Sciences 5 93 of Folinsbee (1961) and Baadsgaard (in Obradovich 1993 and Lerbekmo 2009) were 94 unsuccessful due to a variety of factors, including extensive modern plant cover along the creek 95 bottom and margins, limitations imposed by widespread property development in the area, and 96 inconsistently and imprecisely reported legal land descriptions of the site in published reports. 97 Regardless of those limitations, we regard the Knudsen’s Farm locality as superior to the 98 original Strawberry Creek locality because the BFm at Knudsen’s Farm is much better exposed, 99 and is associated with a more completely exposed stratigraphic section that extends throughout 100 the Red Deer River valley. For example, the Knudsen’s Farm stratigraphic section extends from 101 the Drumheller Marine Tongue of the Horseshoe Canyon Formation at its base, to a few meters 102 above the Cretaceous-Paleogene (K-Pg) boundary at its top, and includes a complete section and 103 laterally extensive outcrops of the 4.5 mDraft thick BFm (Fig. 2; Eberth and Braman 2012, appendix 104 1). Southeast toward Drumheller, bedrock exposures extend down-section into the Campanian- 105 age, marine Bearpaw Formation, and to the north and west, exposures extend up-section into the 106 Paleocene-age, non-marine Scollard and Paskapoo formations (Gibson 1977; Hamblin 2004; 107 Eberth and Braman 2012; Eberth et al. 2013; Prior et al. 2013). 108 109 Stratigraphic and geological background 110 The BFm succession has been recognized as an important Upper Cretaceous 111 lithostratigraphic datum in south-central Alberta and south-western Saskatchewan since the 112 1930s (Sanderson, 1931). It was elevated to formational status by Irish and Havard (1968) and 113 included as part of Edmonton Group by Irish (1970). The formation lies unconformably on the 114 Whitemud Member of the Horseshoe Canyon Formation (Catuneanu et al. 1997; Catuneanu and 115 Sweet 1999; Hamblin 2004; Hathway 2011; Eberth and Braman 2012; and Eberth et al. 2013), https://mc06.manuscriptcentral.com/cjes-pubs Canadian Journal of Earth Sciences Page 6 of 38 6 116 and is overlain conformably by the alluvial Scollard Formation (Fig.