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Map showing publication footprint
  • Usage in publication:
    • Flowery Trail Granodiorite*
  • Modifications:
    • Named
  • Dominant lithology:
    • Granodiorite
  • AAPG geologic province:
    • Okanogan province
Publication:

Clark, L.D., and Miller, F.K., 1968, Geology of the Chewelah Mountain quadrangle, Stevens County, Washington: Washington Division of Mines and Geology, Geologic Map, GM-5, 1 sheet, 6 p., scale 1:62,500


Summary:

Named for and type locality designated as roadcut exposures along Flowery Trail Road, especially near bottom of Chewelah Mountain ski lift [3 to 7 mi northeast of Chewelah, secs.1-4 T32N R41E] Stevens Co, WA. Average rock is medium-grained, hypidiomorphic-granular, hornblende-biotite granodiorite with color index range of 22-45. Dikes as much as 100 m long penetrate wallrock. Appears to have been mildly metamorphosed by muscovite quartz monzonite. Assigned "probable Mesozoic" age.

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


Map showing publication footprint
  • Usage in publication:
    • Flowery Trail Granodiorite*
  • Modifications:
    • Age modified
    • Geochronologic dating
  • AAPG geologic province:
    • Okanogan province
Publication:

Miller, F.K., and Clark, L.D., 1975, Geology of the Chewelah-Loon Lake area, Stevens and Spokane Counties, Washington, with a section on potassium-argon ages of the plutonic rocks by Joan C. Engels: U.S. Geological Survey Professional Paper, 806, 74 p., (incl. geologic map, scale 1:62,500)


Summary:

Description of unit more detailed than Clark and Miller (1968). Three Hornblende (H) - Biotite (B) pairs yield discordant ages:
1. (H) 194 +/- 7 Ma (B) 98 +/- 5 Ma
2. (H) 183 +/- 6 Ma (B) 84 +/- 3 Ma
3. (H) 143 +/- 5 Ma (B) 64 +/- 3 Ma
Samples along 3.3-mile line show consistent age loss in easterly direction; graphing the data, however, suggests "true age" probably not much greater than 195 Ma. Age revised to Late Triassic or Early Jurassic.

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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