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National Geologic Map Database
Map showing publication footprint
  • Usage in publication:
    • Spieden Bluff Formation
  • Modifications:
    • Named
    • Biostratigraphic dating
    • Geochronologic dating
  • Dominant lithology:
    • Conglomerate
    • Sandstone
  • AAPG geologic province:
    • Puget Sound province
Publication:

Johnson, S.Y., 1981, The Spieden Group; an anomalous piece of the Cordilleran paleogeographic puzzle: Canadian Journal of Earth Sciences, v. 18, no. 11, p. 1694-1707.


Summary:

Named as lower formation of Spieden Group. Type section: Spieden Bluff on northwest coast of Spieden Island, sec 2, T37N, R4W. Formerly lower part of Spieden Formation. Chiefly 100 m volcanic breccia-conglomerate, sandstone, siltstone, and tuff divided into two informal members. Lower member debris flow; upper shallow marine. Base not exposed; unconformably overlain by Lower Cretaceous Sentinel Island Formation. Age from BUCHIA CONCENTRICA (Oxfordian or Kimmeridgian) in upper member and hornblende K-Ar date of 148+-9 Ma in lower member. Crops out San Juan Islands only.

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


Map showing publication footprint
  • Usage in publication:
    • Spieden Bluff Formation*
  • Modifications:
    • Geochronologic dating
  • AAPG geologic province:
    • Puget Sound province
Publication:

Johnson, S.Y., Zimmerman, R.A., Naeser, C.W., and Whetten, J.T., 1986, Fission-track dating of the tectonic development of the San Juan Islands, Washington: Canadian Journal of Earth Sciences, v. 23, no. 9, p. 1318-1330.


Summary:

Sample 26 on granodiorite clast of Spieden Formation of Spieden Group gave fission-track age of 147 +/-16 Ma.

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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