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  • Usage in publication:
    • Horseshoe Bar quartz diorite
  • Modifications:
    • Original reference
  • Dominant lithology:
    • Quartz diorite
  • AAPG geologic province:
    • Sierra Nevada province
Publication:

Curtis, G.H., Evernden, J.F., and Lipson, J., 1958, Age determination of some granitic rocks in California by the potassium-argon method: California Division of Mines Special Report, no. 54, 16 p.


Summary:

Pg. 6. Horseshoe Bar quartz diorite. Discussed in report dealing with potassium-argon age determinations. Age 142.9 million years. Rock dated was called gabbro by Lindgren and considered to be local variation of Rocklin granodiorite which surrounds it. [Age is Jurassic.]
[Type locality not stated.] Dated samples collected from quarry in NE/4 sec. 18, T. 11 N., R. 8 E., MD, approx. 3 mi southeast of Loomis, northern CA.

Source: US geologic names lexicon (USGS Bull. 1200, p. 1808).


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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