- Usage in publication:
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- Dobbins Alaskite
- Modifications:
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- Named
- Dominant lithology:
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- Alaskite
- AAPG geologic province:
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- Basin-and-Range province
Summary:
Named for exposures on north flank Dobbins Lookout (its type locality), main ridge of South Mountains, Maricopa Co, AZ, Basin-and-Range province. Reference localities occur on Mount Suppoa and in Boundary Hills. Thought to be a border phase of Telegraph Pass Granite (new). Overlies newly named South Mountains Granodiorite at type. Intrudes Estrella at other localities. Consists of a series of gently dipping sills with strong mylonitic fabric parallel to their margins. Thin mylonitic granodiorite and biotite-rich mylonitic schist lenses are interleaved with the sills. Exposed in Southern Foothills, on Pima ridge, and Boundary Hills. The main phase is fine-grained alaskitic granite, quartz porphyry, and felsite. All phases composed of subequal amounts of alkali feldspar, plagioclase, and quartz. Of middle Tertiary (25 m.y.) age. Geologic map. Is part of (along with South Mountains Granodiorite and Telegraph Pass Granite, new) a composite pluton.
Source: GNU records (USGS DDS-6; Denver GNULEX).
- Usage in publication:
-
- Dobbins Alaskite*
- Modifications:
-
- Overview
- AAPG geologic province:
-
- Basin-and-Range province
Summary:
Is a middle Tertiary unit, and the third or youngest phase of a composite pluton that intrudes the Early Proterozoic Estrella Gneiss in Maricopa Co, AZ, 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 ([ ]).