Development of the Permian-Triassic unconformity in southwestern Utah, southeastern Nevada and northwestern Arizona

Conference · Wed Mar 31 23:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5023854

Nielson, R L ^[1]

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1. Stephen F. Austin State Univ., Nacogdoches, TX (United States). Dept. of Geology

Development of positive areas, that are oriented northwest-southeast in south-western Utah, southeastern Nevada, and northwestern Arizona, are indicated by the depositional patterns of the Rock Canyon Conglomerate and facies changes produced by on-lapping during the deposition of the Timpoweap, Lower Red, and Virgin Limestone Members of the Moenkopi Formation. The lack of facies change in the Kaibab Formation indicates that uplift of the positive areas did not start during the early Permian. The Fossil Mountain Member of the Kaibab Formation, is a marker of continuous shallow marine sedimentation across the area. The Harrisburg Member contains three limestone units, separated by gypsum and shale units, that represent regressions and transgressions. Where the gypsum in the Kaibab Formation thins, collapse breccia and deformed shale units are present indicating that the gypsum was deposited and then removed by dissolution. Channels cut during the late Permian and early Triassic Periods do not cut through the Harrisburg Member of the Kaibab Formation. West of St. George, Utah, where the gypsum deposits are thickest, is the location where Timpoweap, Lower Red, and Virgin Limestone members thin and are absent. Late Permian and early Triassic topography may have in part been controlled by dissolution of the gypsum deposits in the Kaibab Formation. The low angle of discordance between Permian and Triassic units indicated that the area was not subjected to major deformation during the late Permian and early Triassic, but was gently tilted and uplifted.

• OSTI ID: 5023854
• 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

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ARIZONA
CARBONATE ROCKS
CONGLOMERATES
DEPOSITION
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGIC STRATA
GEOLOGIC STRUCTURES
GEOLOGY
GYPSUM
LIMESTONE
MESOZOIC ERA
MINERALS
NEVADA
NORTH AMERICA
PALEOZOIC ERA
PERMIAN PERIOD
ROCKS
SEDIMENTARY ROCKS
STRATIGRAPHY
SULFATE MINERALS
TRIASSIC PERIOD
USA
UTAH