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Geologic Unit: Similkameen
Map showing publication footprint
  • Usage in publication:
    • Similkameen granite
  • Modifications:
    • Named
  • Dominant lithology:
    • Granite
  • AAPG geologic province:
    • Cascades province
    • Okanogan province
Publication:

Daly, R.A., 1906, The Okanogan composite batholith of the Cascade Mountain system [Washington]: Geological Society of America Bulletin, v. 17, p. 329-376.


Summary:

[Named from Similkameen River in north-central WA] Composed of a batholithic soda-rich hornblende-biotite granite. Intrudes Kruger body. Age is late Miocene(?) or Pliocene(?).

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


Map showing publication footprint
  • Usage in publication:
    • Similkameen granodiorite
  • Modifications:
    • Revised
  • Dominant lithology:
    • Granodiorite
  • AAPG geologic province:
    • Cascades province
    • Okanogan province
Publication:

Waters, A.C., and Krauskopf, Konrad, 1941, Protoclastic border of the Colville batholith: Geological Society of America Bulletin, v. 52, no. 9, p. 1355-1418, (incl. geologic map, scale 1:125,000)


Summary:

Redescribed as Similkameen granodiorite. Shown on geologic map of part of border of Colville batholith, near Lamanasky Mountain, Chopaka quadrangle, WA. Is a biotite hornblende granodiorite. Age is Mesozoic.

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


Map showing publication footprint
  • Usage in publication:
    • Similkameen Sub-porphyritic Granodiorite
  • Modifications:
    • Revised
    • Age modified
  • Dominant lithology:
    • Granodiorite
  • AAPG geologic province:
    • Cascades province
    • Okanogan province
Publication:

Hibbard, M.J., 1971, Evolution of a plutonic complex, Okanogan Range, Washington: Geological Society of America Bulletin, v. 82, no. 11, p. 3013-3048, (incl. geologic map, scale 1:62,500)


Summary:

Similkameen Sub-porphyritic Granodiorite in /Horseshoe Basin magma series [informal] (new). Previously called Snehumption Sub-porphyritic Granodiorite (Hibbard, 1965). Mapped along international border, in T. 40 N., R. 23 and 24 E., Toats Coulee Creek region, Okanogan Range, Okanogan County, Washington. Is a light gray-pink, medium-grained, sub-porphyritic granodiorite. Locally contains alkali feldspar phenocrysts up to 2 cm in length. Includes leucocratic variant on Grandview Mountain. Age is Early to medial Cretaceous.
["Horseshoe Basin magma series" considered informal. Term "Series" is applied formally only to chronostratigraphic units (ACSN, 1961, 1970; NACSN, 1983, 2005, 2021).]

Source: Modified from 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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