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Map showing publication footprint
  • Usage in publication:
    • Treadwell slate*
  • Modifications:
    • Named
  • Dominant lithology:
    • Slate
    • Conglomerate
    • Graywacke
  • AAPG geologic province:
    • Alaska Southeastern region
Publication:

Martin, G.C., 1926, Mesozoic stratigraphy of Alaska: U.S. Geological Survey Bulletin, 776, 493 p.


Summary:

Comprises oldest rocks on Treadwell Island, Juneau district southeastern AK. Consists of black clay slate with some conglomerate and considerable graywacke. Thickness is probably 7000 ft. Believed to overlie Thane volcanic group (new) (although Gastineau Channel separates units). Apparently conformably underlies Douglas Island volcanic group (new). Tentatively assigned to Late Jurassic(?) age.

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


Map showing publication footprint
  • Usage in publication:
    • Treadwell formation*
  • Modifications:
    • Redescribed
    • Areal extent
    • Age modified
  • Dominant lithology:
    • Slate
    • Graywacke
    • Breccia
    • Schist
  • AAPG geologic province:
    • Alaska Southeastern region
Publication:

Barker, Fred, 1957, Geology of the Juneau (B-3) quadrangle, Alaska: U.S. Geological Survey Geologic Quadrangle Map, GQ-100, 1 sheet, scale 1:63,360


Summary:

Treadwell slate of Martin (1926) is redescribed as Treadwell formation. Is northwesterly extension of Treadwell slate of Juneau area. Consists of black, graphitic slate and interlayered gray to green, fine-grained, poorly schistose to massive plagioclase-quartz-sericite-chlorite graywacke. Also contains lenses of green, massive flow breccia and schist. Age is Jurassic(?) to Early Cretaceous(?) based on correlation with probable equivalent strata at Berners Bay.

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


Map showing publication footprint
  • Usage in publication:
    • Treadwell Formation*
  • Modifications:
    • Age modified
  • AAPG geologic province:
    • Alaska Southeastern region
Publication:

Miller, L.J., Goldfarb, R.J., Snee, L.W., Gent, C.A., and Kirkham, R.A., 1995, Structural geology, age, and mechanisms of gold vein formation in the Kensington and Jualin deposits, Berners Bay district, southeast Alaska: Economic Geology, v. 90, no. 2, p. 343-368.


Summary:

Age of the Treadwell Formation is revised from Jurassic(?) to Early Cretaceous(?) to: Early and Late Cretaceous.

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


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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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