Uppermost Precambrian and lowest Cambrian rocks in southeastern Idaho, with contributions to Early Middle Cambrian faunal zones

Abstract

Meaning and problems of the Brigham__ Previous usage. -______-____--____ Definition ___________________ Idaho usage. _________________ Utah usage. _________________ Modifications proposed for Brigham. Formation versus Quartzite _ Abandonment versus retention. Restricted versus inclusive_____ Regional relations. _______________ 1. Stratigraphic sections of the rocks beneath the Bloomington Formation in the Bancroft and Soda Springs quadrangles. 2. Stratigraphic sections of the upper part of the Brigham Quartzite measured southeastward along the Portneuf Range to the western part of the Bear River Range. 3. Described measured sections of the Brigham Quartzite and associated rocks in southeastern Idaho and northern Utah. 4-6. Described Stratigraphic sections between the Bloomington Formation and the Brigham Quartzite showing former and new rock-stratigraphic assignments: 4. Eastward from the Bannock Range, across the Portneuf Range to the northeastern Bear River Range. 5. Eastward from the Malad Range, across the southern part of Portneuf Range to the east side of the Bear River Range. 6. Eastward across the Wasatch Range in northern Utah. 7. Sections showing relation of rock-stratigraphic assignments in the Bancroft and Soda Springs quadrangles to recognized Cambrian faunal zones. Index map of southeastern Idaho and northern Utah, showing the locations of the Bancroft, Soda Springs, and Preston quadrangles and of the Stratigraphic sections discussed---____..______-__-_-______-_____---____ Relief map of southeastern Idaho and northern Utah, showing the major physiographic features mentioned and their relations to the Bancroft, Soda Springs, and Preston quadrangles-___--__-_-_____________-______..

Cambrian trilobites from the Glossopleura walcotti Zone (Miaolingian Series, Wuliuan Stage) of Mendoza, western Argentina

“…crassa . This species also was reported from the Bear River Range, southern Idaho, by Fritz in Oriel and Armstrong (1971, p. 43).…”

“…Both Glossopleura leona and Kootenia crassa , which are reported from the Argentine Precordillera for the first time, indicate a close affinity with the Glossopleura walcotti Zone of the Arrojos Formation at Cerro Los Difuntos and Cerros La Proveedora, Caborca, Sonora (Lochman in Cooper et al, 1952; Stewart et al, 1984; Cuen-Romero et al, 2018). Kootenia crassa also is known from coeval levels of east-central Nevada (Pioche Shale) (Fritz, 1968) and the Bear River Range, southeastern Idaho (Fritz in Oriel and Armstrong, 1971).…”

“…Copenhagen Canyon, Bear River Range, southeastern Idaho; ? Glossopleura walcotti Zone (Fritz in Oriel and Armstrong, 1971, p. 43). Cerro Martillo, Quebrada Oblicua, Quebrada Empozada, and Quebrada San Isidro, San Isidro area, Mendoza; San Isidro Olistoliths, Glossopleura walcotti Zone.…”

Chemostratigraphy of predominantly siliciclastic Neoproterozoic successions: a case study of the Pocatello Formation and Lower Brigham Group, Idaho, USA

“…Age and correlation Fossils are extremely rare in the Neoproterozoic rocks of northern Utah and southeastern Idaho. 2; Crittenden et al 1971;Oriel & Armstrong, 1971;Link et al 1987), indicating that at least the top of the unit is of Cambrian age. Coarse-grained quartz sandstones such as those found in the Brigham Group have long been recognized as typical of facies containing the biologically and temporally distinctive Ediacaran fauna (Glaessner, 1984).…”

Changes in stratigraphic nomenclature by the U.S. Geological Survey, 1972

“…Cub Tongue adopted as uppermost unit of Lead Bell Shale (new); farther east it is reassigned and adopted as Cub Shale Member, lowermost unit of Ute Limestone where twofold subdivision is possible. (Oriel and Armstrong, 1971.) Geographically extended into western Texas.…”