- Usage in publication:
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- Makushin volcanics*
- Modifications:
-
- Named
- Dominant lithology:
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- Basalt
- Pyroclastics
- AAPG geologic province:
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- Aleutian Islands province
- Alaska Southwestern region
Summary:
Forms Makushin Volcano, broad volcanic dome more than 6000 ft high and 10 mi wide, Unalaska Island, Aleutian Islands, AK. Restricted to northern part of northern bulge of island. Consists of basalt and subordinate andesite lava, pyroclastic rocks, and minor sedimentary rocks. Basalt plugs, sills and dikes separately mapped on geologic map of Unalaska Island. Thickness is probably several 1000 ft. Unconformably overlies Unalaska formation (new) and granodiorite pluton; unconformably underlies Eider Point basalt (new); locally unconformably capped by basaltic flows and pyroclastic rocks. Age is Pliocene(?) and Pleistocene based on stratigraphic relations with plutons and glaciation.
Source: GNU records (USGS DDS-6; Menlo 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 ([ ]).