- Usage in publication:
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- Alvord Creek beds
- Modifications:
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- Named
- Dominant lithology:
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- Tuff
- Andesite
- AAPG geologic province:
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- Great Basin province
Summary:
Probably named for occurrences near base of Steens Mtn scarp between Cotton Wood and Little Alvord Creek. Well stratified acidic tuffs. Consists of (descending): l)white tuff, 100+/-ft.; 2) basic andesite flow, 100+/-ft.; 3)white tuffaceous sediments, 200 +/-ft.; 4)buff stratified tuff, 50 ft.; 5) brownish tuffs, 200+/-ft. Underlies Pike Creek volcanic series in S part of Steens Mtn; underlies Steens Mountain andesitic series in N part. Intruded by 200 ft of basaltic sill N of Little Alvord Creek. "A small flora indicates these beds [Alvord Creek beds] to be of middle Miocene age, thus approximately corresponding to the Mascall Formation."
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
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- Alvord Creek formation
- Modifications:
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- Revised
- Age modified
- AAPG geologic province:
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- Great Basin province
Summary:
Alvord Creek beds of Fuller (1931) are here designated Alvord Creek formation "following the rules of geologic nomenclature (GSA Bull., v.44, p.433-435)". Assigned early Pliocene age on basis of flora.
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
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- Alvord Creek formation*
- Modifications:
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- Adopted
- Biostratigraphic dating
- AAPG geologic province:
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- Great Basin province
Summary:
Alvord Creek beds (Fuller, 1931) ["adopted as Alvord Creek Formation to conform to 'Code'."] Unconformably overlies pre-Tertiary rocks. Assigned early Pliocene age based on fossil leaves (Axelrod, 1944, p.241-248).
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
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- Alvord Creek Formation*
- Modifications:
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- Geochronologic dating
- AAPG geologic province:
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- Great Basin province
Summary:
K-Ar age on basalt sample (from flow 200 feet above fossil plant-bearing tuffaceous shale on north fork of Alvord Creek, east flank of Steens Mountain, Oregon) gave 21.3 Ma. "Undescribed Barstovian mammals have been collected from ... Steens Basalt. Therefore, mammals criteria require that the Alvord Creek flora be Barstovian or older." "Age according to K-Ar date is late Arikareean."
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
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- Alvord Creek Formation*
- Modifications:
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- Age modified
- AAPG geologic province:
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- Great Basin province
Summary:
Age changed from early Pliocene to early Miocene [cites radiometric age of 21.3 Ma by Evernden and James, 1964]
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
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- Alvord Creek Formation*
- Modifications:
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- Age modified
- AAPG geologic province:
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- Great Basin province
Summary:
Underlies Pike Creek Formation (contrary to Walker, 1979) with slight angular unconformity. Basalt flow dated by Evernden and James (1964) at 21.3 Ma previously included in Alvord Creek Formation (and included in or above the Alvord Creek by Walker, 1979) now included in Steens Mountain Volcanics. Therefore age changed from early Miocene to Oligocene(?) and Miocene.
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
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- Alvord Creek Formation*
- Modifications:
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- Age modified
- AAPG geologic province:
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- Great Basin province
Summary:
Age revised from Oligocene(?) and Miocene to Oligocene and(or) Miocene based on stratigraphic relations with the overlying Pike Creek Formation.
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 ([ ]).