- Usage in publication:
-
- Piper Gulch Monzonite*
- Modifications:
-
- Named
- Geochronologic dating
- Dominant lithology:
-
- Monzonite
- AAPG geologic province:
-
- Basin-and-Range province
Summary:
Named. Type locality is near the jeep road in Piper Gulch in Santa Rita Mountains, Santa Cruz Co, AZ, Mount Wrightson quad. Forms a string of bodies that lie along crest of southern part of Santa Rita Mountains. Very coarse-grained, dark-gray monzonite. Intrudes Triassic Mount Wrightson Formation and is intruded by Jurassic Squaw Gulch Granite. A zircon from the unit was radiometrically dated at 184 Ma by the lead-alpha method. Is assigned a Triassic age.
[NOTE: The Department of the Interior's Secretarial Order 3404, issued on November 19, 2021, formally identifies the term “squaw” as derogatory. That Order will create a federal Derogatory Geographic Names Task Force, to find replacement names for geographic features in use by federal agencies. We’re awaiting guidance from the Task Force, and will then take the appropriate actions.]
Source: GNU records (USGS DDS-6; Denver GNULEX).
- Usage in publication:
-
- Piper Gulch Monzonite*
- Modifications:
-
- Geochronologic dating
- AAPG geologic province:
-
- Basin-and-Range province
Summary:
Cuts the lower member and base of middle member of Mount Wrightson Formation. Gave a concordant zircon U-Th-Pb age of 188 +/-2 Ma on samples collected in southern AZ in the Basin-and-Range province.
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 ([ ]).