AN EARLY CAMBRIAN FAUNA FROM THE CARRARA FORMATION, EMIGRANT PASS, NOPAH RANGE, INYO COUNTY, CALIFORNIA: A PRELIMINARY NOTE
by Jack D. Mount¹
The Carrara Formation of Cornwall and Kleinhampl (1961), exposed in the southern Great Basin in portions of eastern California and southeastern Nevada, consists of a heterogeneous assemblage of clastic and carbonate rocks of the geoclinal slope facies. The formation is moderately fossiliferous and Palmer and Halley (1979) have assigned an age of early Late Cambrian through the early part of the Middle Cambrian Glossopleura Zone. An excellent uncomplicated and easily accessible section of the Carrara Formation is located in Emigrant Pass in the southern part of the Nopah Range. In February 1977, I visited this area and made a stratigraphic collection of fossils from a section exposed in the NE 1/4 of the SW 1/4 of the SE 1/4 of Section 25, T. 21 N., R. 8 E., Tecopa 15' Quadrangle (1951 edition). The rocks in this section yielded only Early Cambrian fossils.
The first important contribution to the knowledge of the Cambrian rocks of the Nopah Range was made by Hazzard (1937). He assigned the strata now included in the Carrara Formation to the upper part of his Wood Canyon Formation and to his Cadiz Formation. He listed a small Early Cambrian fauna from these beds. Wheeler (1948) assigned the rocks above the Zabriskie Quartzite to the base of Hazzard's unit 5E to his Tecopa Shale. This unit is not acceptable and all the strata between the top of the Zabriskie Quartzite and the base of the Bonanza King Dolomite are assigned to the Carrara Formation. Recently, Palmer and Halley (1979) have made a major study of the stratigraphy, environment of deposition and paleontology of the Carrara Formation and have described a fauna of 95 species of trilobites from the Bonnia-Olenellus, Plagiura-Poliella, Albertella and Glossopleura Zones.
During my study fossils were collected from 29 m to 141 m above the base of the formation. This assemblage of fossils, listed in Table 1, is assigned to the Bonnia-Olenellus Zone of Rasetti (1951) and to the following subzones in ascending order: Bristolia Subzone of Mount (1974), Olenellus puertoblancoensis Subzone of Mount (1976) and Olenellus multinodus Zonule of Palmer and Halley (1979). The stratigraphic ranges of the fossils are shown in figure 1.
The Carrara Formation is correlative with the lower Cambrian Latham Shale-Chambless Limestone-Cadiz Formation shelf or cratonic facies of eastern San Bernardino County (Mount, 1980) and the upper Saline Valley Formation-Mule Spring Limestone basinal facies of the White-Inyo Mountains area (Nelson, 1976).
Cornwall, H. R., and Kleinhampl, F. J., 1961. Geology of the Bare Mountain Quadrangle, Nevada. U. S. Geol. Survey Map GQ-157.
Hazzard, J. C., 1937. Paleozoic section in the Nopah and Resting Springs Mountains, Inyo County, California. California Jour. Mines Geol. 33:273-339.
Mount, J. D., 1974. Early Cambrian faunas from the Marble and Providence Mountains, San Bernardino County, California. Bull. So. California Paleon. Soc. 6:1-5.
__________, 1976. Early Cambrian faunas from eastern San Bernardino County, California. Bull. So. California Paleon. Soc. 8:173-182.
__________, 1980. Characteristics of Early Cambrian faunas from eastern San Bernardino County, California. in Paleontological tour of the Mojave Desert, California-Nevada. So. California Paleon. Soc. Spec. Publ. 2:19-29.
Nelson, C. A., 1976. Late Precambrian-Early Cambrian stratigraphic and faunal succession of eastern California and the Precambrian-Cambrian boundary. in Depositional environments of lower Paleozoic rocks in the White-Inyo Mountains, Inyo County, California. Pacific Coast Paleogeog. Field Guide 1:31-42.
Palmer, A. R., and Halley, R. B., 1979. Physical stratigraphy and trilobite biostratigraphy of the Carrara Formation (Lower and middle Cambrian) in the southern Great Basin. U. S. Geol. Survey Prof. Paper 1047:1-131.
Rasetti, F. 1951. Middle Cambrian stratigraphy and faunas of the Canadian Rocky Mountains. Smithsonian Misc. Colln. 116(5):1-277.
Wheeler, H. E., 1948. Late Pre-Cambrian-Cambrian stratigraphic cross section through southern Nevada. Univ. Nevada Bull. 42(3):1-61.
Paterina cf. P. prospectensis (Walcott, 1884)
Novitatus n. sp. [Mount, 1980, fig. 23]
Bristolia anteros Palmer, 1979
Bristolia bristolensis (Resser, 1928)
Bristolia fragilis Palmer, 1979
Bristolia n. sp. [Mount, 1980, fig. 16]
Olenellus clarki (Resser, 1928)
Olenellus brachyomma Palmer, 1979
Olenellus euryparia Palmer, 1979
Olenellus fremonti Walcott, 1910
Olenellus gilberti Meek in White, 1874
Olenellus nevadensis (Walcott, 1910)
Olenellus howelli Meek in White, 1874
Olenellus puertoblancoensis (Lochman, 1952)
Peachella brevispina Palmer, 1979
Peachella iddingsi (Walcott, 1884)
Olenellid-n. gen. & sp. [Mount, 1980, fig. 32]
Crassifimbra n. sp.
Periomma n. sp.
Ptychopariid-n. gen. & sp. B
Fig. 1. Stratigraphic distribution of Early Cambrian fossils from the Carrara Formation at Emigrant Pass.
¹Department of Earth Sciences, University of California, Riverside, CA 92521.
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