- Usage in publication:
-
- Alkali Gulch "cycle"
- Modifications:
-
- First used
- AAPG geologic province:
-
- Paradox basin
Summary:
Alkali Gulch "cycle" is first used in reference to a pre-Barker Creek cycle in the Paradox Formation. Age is [Middle] Pennsylvanian (Desmoinesian).
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
-
- Alkali Gulch Formation
- Modifications:
-
- Revised
- AAPG geologic province:
-
- Paradox basin
Summary:
Revised to the Alkali Gulch Formation of the Paradox Group. Age is Pennsylvanian (Desmoinesian).
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
-
- Alkali Gulch Formation
- Modifications:
-
- Named
- AAPG geologic province:
-
- Paradox basin
Summary:
Unit is named the Alkali Gulch Formation of the Paradox Group. Also referred to as the Alkali Gulch cycle of the Paradox Formation of the Hermosa Group. Consists of cyclic deposits of limestone, dolomite, shale, sandstone, anhydrite, and salt. Thickness is 34 m. Overlies the Pinkerton Trail Formation; underlies the Barker Creek substage of the Four Corners stage. Age is Middle Pennsylvanian (Desmoinesian). (B1520)
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
-
- Alkali Gulch production interval
- Modifications:
-
- Overview
- Dominant lithology:
-
- Shale
- Anhydrite
- Dolostone
- Halite
- AAPG geologic province:
-
- Paradox basin
Summary:
Is lowermost production interval (of 5) in the Paradox Member (Atokan? and Desmoinesian) of the Middle and Upper Pennsylvanian Hermosa Formation (Atokan, Desmoinesian, Missourian, and Virgilian) in the Paradox basin of southeast UT and southwest CO. Overlies Pinkerton Trail Member of the Hermosa. Underlies Barker Creek production interval of the Paradox Member. Includes evaporite cycles 29-21 (ascending) and in upper part the "Cane Creek" interval is shown as equivalent to cycle 22. "The base and top of the Paradox Member of the Hermosa Formation is usually defined by the first and last halite beds. In the deep part of the Paradox basin, the member consists of 29 identifiable evaporite cycles (Hite, 1960), and its maximum depositional thickness was probably about 7,000 ft (2130.9 m). These cycles are bounded by disconformities and when complete the sequential order from the base upward is (a) anhydrite, (b) very silty fine grained dolomite, (c) silty calcareous black shale, (d) silty fine grained dolostone, (e) anhydrite, and (f) halite with or without potash salts. With the exception of the black shale unit, all of the elements of the cycle were deposited in response to salinity changes in the brine basin. In the deep part of the Paradox basin, the cyclical sequence consists of up to 80 percent halite. Going from basin deep to basin shelf, the amount of halite in the cycles diminishes while the percentage of dolostone and anhydrite increases."
Source: GNU records (USGS DDS-6; Denver GNULEX).
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
Asterisk (*) indicates published by U.S. Geological Survey authors.
"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).
Slash (/) indicates name conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).