Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8916210 | Cretaceous Research | 2018 | 19 Pages |
Abstract
40Ar/39Ar dating of a bentonite associated with a cold methane seep deposit in the upper Campanian Baculites compressus Zone of the Pierre Shale in South Dakota yields an age of 73.79 ± 0.36 Ma. This is in close agreement with the previously published age of 74.05 ± 0.39 Ma for this zone (Obradovich, 1993) and nearly identical to an unpublished age of 73.70 ± 0.13 Ma for the same zone, both samples of which are from a more proximal locality near the base of the Bearpaw Shale in Montana, as recalculated relative to a Fish Canyon standard age of 28.201 Ma. We also report dates for two bentonites from the upper Campanian Exiteloceras jenneyi and Didymoceras stevensoni zones.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Palaeontology
Authors
Neil H. Landman, Brian R. Jicha, J. Kirk Cochran, Matthew P. Garb, Shannon K. Brophy, Neal L. Larson, Jamie Brezina,