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Geologic Unit: Tanak
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Map showing publication footprint
  • Usage in publication:
    • Tanak volcanics*
  • Modifications:
    • Named
  • Dominant lithology:
    • Volcaniclastics
    • Volcanics
  • AAPG geologic province:
    • Aleutian Islands province
    • Alaska Southwestern region
Publication:

Byers, F.M., Jr., Hopkins, D.M., Wier, K.L., and Fisher, Bernard, 1947, Volcano investigations on Umnak Island, IN Progress of investigations in 1946: U.S. Geological Survey Alaskan Volcano Investigations Report, no. 2, p. 19-53.


Summary:

Named for Cape Tanak in southwestern part of Unalaska 1:250,000 quad, Umnak Island, Aleutian Islands, AK (Byers, 1947). [no type designated] Occurs high on walls of Mount Okmok caldera and on outer slopes to north and northeast. Consists of thick beds of tuff-breccia with many thin beds of agglomerate and few interbedded lava flows. [Unconformably] overlain by Okmok ash (new) and (locally) alluvium. [Unconformably] underlain (locally) by Idak basalt, Crater Creek basalt, Ashishik basalt (all new), and unnamed volcanic and volcaniclastic rocks. Age is given as Quaternary (based on regional stratigraphic relations).

Source: GNU records (USGS DDS-6; Menlo GNULEX).


Map showing publication footprint
  • Usage in publication:
    • Tanak volcanics†
  • Modifications:
    • Abandoned
  • AAPG geologic province:
    • Aleutian Islands province
    • Alaska Southwestern region
Publication:

Byers, F.M., Jr., 1959, Geology of Umnak and Bogoslof Islands, Aleutian Islands, Alaska, IN Investigations of Alaskan volcanoes: U.S. Geological Survey Bulletin, 1028-L, p. L267-L369.


Summary:

Tanak volcanics of Byers and others (1947) is abandoned and rocks are reassigned to (here-redefined) Okmok volcanics.

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 ([ ]).

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