Age and correlation of the unclassified dolomites of the Grand Canyon
- Univ. of Nevada, Las Vegas, NV (United States). Dept. of Geoscience
Overlying the Muav Limestone in the Grand Canyon is an interval of dolomite that McKee (1945) described as unclassified Cambrian dolomites.'' These dolomites are unfossiliferous, and their age has remained uncertain. By measuring sections in the western Grand Canyon and in the Lake Mead region, the authors have been able to correlate members of the Muav Limestone and the overlying unclassified dolomites with portions of the Bonanza King Formation as far west as Frenchman Mountain. The Rampart Cave, Sanup Plateau, and Spencer Canyon Members of the Muav correlate with the Papoose Lake Member of the Bonanza King, while the Peach Springs, Kanab Canyon, Gateway, and Havasu Members of the Muav correlate with the lower part of the Banded Mountain Member of the Bonanza King Formation. Much of this section in both formations consists of peritidal parasequences, and Fischer plots of these parasequences has assisted in the correlation. The Frenchman Mountain section is a critical one because it contains the distinctive and well-dated Nopah Formation, whose base is Dresbachian (lowermost Upper Cambrian). The Nopah Formation and equivalent strata were removed by pre-Devonian erosion from all sections east of Frenchman Mountain. The unclassified dolomites of the Grand Canyon correlate with a portion of the Banded Mountain Member of the Bonanza King Formation, well below the base of the Nopah Formation. Because the Middle-Upper Cambrian boundary is not precisely located in the Bonanza King Formation, it is not yet possible to locate this boundary in the unclassified dolomites either. It is probable, however, that the unclassified dolomites are entirely Middle Cambrian.
- OSTI ID:
- 5129138
- Report Number(s):
- CONF-9305259--
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Journal Name: Geological Society of America, Abstracts with Programs; (United States) Vol. 25:5; ISSN GAAPBC; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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