...W. D. KELLER Abstract The Rex chert member of the Phosphoria formation of Permian age was studied petrographically from specimens collected across the stratigraphic sections at five localities in Idaho, Wyoming, and Utah. The Rex is a fine-grained quartzite with chert in its upper part in the Big...

... in the Chugwater formation. In its typical region in southeastern Idaho, the Phosphoria consists of an upper chert and limestone—the Rex chert member—and a lower phosphatic shale member. It is overlain by the Woodside shale of Lower Triassic age and underlain by the Wells formation of Pennsylvanian age. At the top...

... grains. The black phosphatic chert was derived from the Rex Chert Member of the Phosphoria Formation west and southwest of the Casper Arch area, possibly in eastern and central Idaho. The Lakota detritus consists predominantly of multi-cycle, subrounded to well rounded grains of plutonic quartz...

... such as uranium, selenium, and cadmium over very short time spans. Anomalously high concentrations of selenium and other environmentally sensitive elements in the Rex Chert member are described in chapter 14. Chapters 15, 16, 17, and 18 detail selenium concentrations in air, stream, and wetland settings, and its...

... it is separated from the main body of the Woodside by a recognizable tongue of the Rex chert member of the Phosphoria. Dr. Williams carries the name beyond the limits of a tongue of the Rex, there draws the boundary between the Mackentire and the Woodside “arbitrarily at the top of the highest bed of gray shale...

... are the Meade Peak phosphatic shale member (the phosphatic shale member of Richards and Mansfield, 1912 ), the lower chert member, the Rex chert member, the cherty shale member, the Retort phosphatic shale member, and the Tosi chert member. Members of the Park City formation are the lower member, the Franson...

... in the Cassia Mountains represents the southwesternmost exposure of the Phosphoria in SE Idaho and includes both the Meade Peak Phosphatic Shale and overlying Rex Chert members. The Meade Peak is distinguished by dark-brown, thin-bedded siltstone with minute white-weathering phosphatic oolites or pellets...

... in central Wyoming. 18 Although they are weaker beds and constitute a part of the shaly phase of the formation, at least in their lower part, they are readily distinguished from the black phosphatic shales below, and are hence considered a part of the Rex member. They mark the lowest development of chert...

.... Uppermost Paleozoic rocks throughout the northern part of the Basin-Range province have been described by Bissell (1960 , 1962 ) who recognized the following section in the Sublett Range: Triassic rocks Park City Group (Guadalupian) Cherty shale [Member of the Phosphoria Formation] Rex Chert...

... saturation. The upper contact appears to be conformable. Rex Member (50 to 80 ft, 15 to 24 m) —A variable sequence of gray shale, siltstone, quartzose sandstone and lithic (chert-rich) sandstone. Present are foraminifers in shales near the base ( Fuglem, 1970 ) and coal near the top (see Wickenden...

... Chert, Meade Peak Phosphatic Shale Member, Rex Chert Member, Retort Phosphatic Shale Member, Cherty Shale, and Tosi Chert Member (McKelvey et al. 1959 ; Sheldon 1963 ; Cressman and Swanson 1964 ; Yochelson and Van Sickle 1968 ). These units represent a lowstand to transgressive systems tract...

... 60 feet below the Rex chert member of the Phosphoria in western Wyoming. Stacheoceras, Vidrioceras, Gastrioceras and Goniatites are represented by species which are closely related to known Middle Permian forms. These new species, he says, are almost certainly Middle Permian in age. 25...

... , 1916a , 1916b , 1920a , 1920b , 1927 , 1929 ) did not recognize the Dinwoody formation in southeastern Idaho. He classified all the Lower Triassic rocks between the Rex chert member of the Phosphoria formation and the Meekoceras zone of the Thaynes formation as Woodside shale. Newell...

... J. geol. Soc. London 1982 139 701 11 Peterman Z. E. Hedge C. E. Tourtelot H. A. Isotopic composition of strontium in sea water throughout Phanerozoic time Geochim. cosmochim. Acta 1970 34 105 20 Rex D. C. Geochronology in relation to the stratigraphy...

... and Shumard, 1850 ) and the Devonian C. rex McIntosh, 1984 . Table 1 —Time ranges of Mississippian botryocrinids treated in this paper. Time intervals 1 through 8 follow Ausich et al. (1994, fig. 1) and are: 1, lower Burlington Limestone; 2, upper Burlington Limestone; 3, Montrose Chert Member of Keokuk...

... to thicknesses of “phosphatic Phosphoria facies” “up to approximately 700 feet in southeastern Idaho” must refer to the entire formation, which there includes more chert, cherty mudstone, and mudstone than phosphorite and phosphatic mudstone. REFERENCES Anderson , Alfred L. , 1931 , “ Geology...

... primarily by the Stockade Beaver Shale, but is also present in the lower portion of the Canyon Springs Member. Facies C2 was deposited on the inner portion of a carbonate ramp, one characterized by relatively quiet water, as indicated by the dominance of bioturbation over physical sedimentary structures...