- Usage in publication:
-
- Pinnacle Peak Phyllite*
- Modifications:
-
- Named
- Dominant lithology:
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- Phyllite
- AAPG geologic province:
-
- Alaska Southeastern region
Summary:
Type locality designated as exposures that extend from Pinnacle Peak southeastward for distance of at least 15 mi, Chichagof Island, southeastern AK. Crops out in belt averaging one mi wide near west coast of Chichagof Island. Consists of thinly laminated, siliceous phyllite which is generally dark-gray fine-grained and contains abundant light-gray and yellowish-gray laminae from 1 to 25 mm thick. Overlies Goon Dip Greenstone or intervening Whitestripe Marble; underlies Waterfall Greenstone. Age given as Triassic(?) on geologic map of Chichagof Island and northwestern Baranof Island.
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
-
- Pinnacle Peak Phyllite*
- Modifications:
-
- Revised
- AAPG geologic province:
-
- Alaska Southeastern region
Summary:
Pinnacle Peak Phyllite is assigned to Kelp Bay Group. No fossils have been found in phyllite. Age is Triassic(?) on basis of stratigraphic relation to Whitestripe Marble which is considered Triassic(?) on basis of questionable faunal evidence. Pinnacle Peak Phyllite correlates with unnamed phyllite unit of undivided Kelp Bay Group on Baranof Island.
Source: GNU records (USGS DDS-6; Menlo GNULEX).
- Usage in publication:
-
- Pinnacle Peak Phyllite*
- Modifications:
-
- Age modified
- AAPG geologic province:
-
- Alaska Southeastern region
Summary:
Pinnacle Peak Phyllite of Kelp Bay Group is assigned to informal Freeburn assemblage of Chugach terrane. Unit has highest metamorphic grade of all Kelp Bay Group rocks. Age was originally based on its relationship to Whitestripe Marble which is assigned to Wrangellia terrane. (Whitestripe Marble is separated from Chugach terrane and Kelp Bay Group by the Border Ranges Fault.) Age of Pinnacle Peak Phyllite now considered to be Cretaceous(?) on basis of its relationship to Kelp Bay Group.
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 ([ ]).