Paleontology and deposition of the Phosphoria Formation

Abstract

The Phosphoria Formation and related rocks were deposited in an interior sag basin developed in the Cordilleran miogeocline of western North America. Deposition can be characterized as a fringing bank complex on a carbonate ramp. Conodont-brachiopod biostratigraphy provides a sufficient relative time framework for correlation of the many units. These age correlations and the distribution of fossils, plus the biofacies of conodonts and brachiopods in particular, indicate that phosphate deposition was a cool-water, deeper ramp facies that transgressed over the carbonate bank twice, representing the Meade Peak and Retort Phosphatic Shale Members of the Phosphoria Formation. Conodont data that substantiate the above are presented, and a new genus and species, Sweetina triticum, is described.