- Usage in publication:
-
- Sutro tuff member
- Modifications:
-
- Named
- Dominant lithology:
-
- Tuff
- AAPG geologic province:
-
- Great Basin province
Summary:
Sutro tuff member of the Alta andesite series (new) is named for exposures in the Sutro tunnel, Silver City district, Storey Co, [Virginia City 15' quad], NV. Tuff is composed of fine volcanic dust and ash, with particles up to 0.25 in; occasional lenses much coarser; color is usually creamy-yellow to light buff. Petrography indicates rhyolite composition. Thickness is variable (250-800 ft) and the unit lies 500-600 ft above base of Alta andesite series. Age possibly ranges from Eocene to Miocene on the basis of stratigraphic position; author's opinion is that age is Miocene.
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
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- Sutro member*
- Modifications:
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- Adopted
- Redescribed
- Dominant lithology:
-
- Shale
- Tuff
- AAPG geologic province:
-
- Great Basin province
Summary:
Sutro [tuff] member of Alta andesite [series] of Gianella (1936) is adopted as Sutro member of Alta andesite. Unit is described as sedimentary as it is difficult to determine the amount of true tuff. Consists of regularly banded shale of sage-green color; grades into coarser material. Is clearly water-lain. Composition is variable; rhyolitic, andesitic, pebbles of pre-Tertiary sedimentary rocks. Age is Miocene (middle or upper) on the basis of leaves (identified by R.W. Brown) and stratigraphic position.
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
-
- Sutro member*
- Modifications:
-
- Age modified
- Biostratigraphic dating
- AAPG geologic province:
-
- Great Basin province
Summary:
Age of Sutro member of Alta formation is Oligocene(?) on the basis of leaves found in road cut in Long Canyon (Axelrod, 1949).
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
-
- Sutro Member*
- Modifications:
-
- Age modified
- AAPG geologic province:
-
- Great Basin province
Summary:
Age of Alta Formation is Miocene on the basis of K-Ar data. [member is not mentioned in reference; see also Whitebread (1976)]
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 ([ ]).