Late Cambrian stratigraphy and conodonts of southern Nevada

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Abstract
The Dunderberg Shale and Halfpint Members of the Nopah Formation in the southern Nevada portion of the Great Basin consist of interbedded shale, limestone, and dolostone. In four measured sections these two members range in thickness from 23 to 82 m and contain abundant sedimentary structures and macro- and microfossils. Trilobites and inarticulate brachiopods indicate the rocks are of medial Late Cambrian (Dresbachian and Franconian) age and correlate with other sections described from the Great Basin. Conodonts were found in limestones and dolostones that contain trilobites of the Dunderbergia and overlying Elvinia Biozones; approximately 3,740 conodonts were recovered and were assigned to one protoconodont and 13 paraconodont single-element form-species. New form-species of Furnishina and Prooneotodus were recognized but not named. Characteristics and distribution of the lithofacies, fossils and organo-sedimentary structures indicate that subtidal sediments formed towards the northwest on a broad, shallow, westward sloping shelf, and intertidal channel and algal bank deposits formed towards the southeast in a craton margin setting.