WUJIAJIANIA SUTHERLANDI FAUNA (ELVINIA BIOZONE, PAIBIAN STAGE, FURONGIAN SERIES—“UPPER” CAMBRIAN) FROM THE EMIGRANT FORMATION, NEVADA

Abstract

Fossils from the Emigrant Formation of Nevada are rare despite the geologic time (uppermost Lower Cambrian to Lower Ordovician) represented by the 700 m thick sequence of deeper water, fine-grained clastics and carbonates. This report documents trilobites from the Elvinia Biozone from this formation in the Goldfield Hills, Nevada. Previously, trilobites and inarticulate brachiopods from the Emigrant Formation have been reported from the lowermost and uppermost portions. In the lower portion, trilobites from the Olenellus Biozone (Dyeran Stage, “Lower” Cambrian) occur in the basal few meters, and are overlain by 15 m of mudstones containing the Eokochaspis nodosa , Amecephalus arrojosensis , and Oryctocephalus indicus biozones (Lin and Knox, 2001; Sundberg and McCollum, 2003) of the lower Delamaran Stage (“Middle” Cambrian, Fig. 1 ). Collections above the lower mudstones include the Glossopleura Biozone of the Delamaran Stage, Ehmaniella ? Biozone of the Topazan Stage, and the Ptychagnostus atavus and Cedaria selwyni biozones of the Marjuman Stage (unpublished data). The only other fossil remains that have been reported include a possible Elvinia Biozone fossil from the middle portion of the formation (McCollum and Sundberg, 2000) and Saukia Biozone fossils from the upper portion of the formation (Albers and Stewart, 1972; unpublished data). Lower Ordovician conodonts have also been found in the upper portion of the formation (M. Miller, personal commun. to L. McCollum, 2003). Figure 1 —Stratigraphic section and biozonation of the lower two-thirds of the Emigrant Formation, Goldfield Hills, Nevada. Biozones marked with an * are based on correlation to the Split Mountain Section near Tonopah, Nevada, which is more condensed than the section at Goldfield Hills (see McCollum and Sundberg, 1999; Sundberg and McCollum, 2003). The stages listed are the Laurentian stages proposed by Ludvigsen and Westrop (1985), …