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Tertiary intrusive rocks (hypabyssal), unit 4 (Tranquillon-Obispo)

Tertiary intrusive rocks; mostly shallow (hypabyssal) plugs and dikes. Includes some Mesozoic rocks.
State California
Name Tertiary intrusive rocks (hypabyssal), unit 4 (Tranquillon-Obispo)
Geologic age Tertiary
Comments includes Morro Rock intrusions
Primary rock type rhyolite
Secondary rock type dacite
Other rock types basalt
Lithologic constituents
Major
Igneous > Hypabyssal > Felsic-hypabyssal > Hypabyssal-rhyolite (Pluton)
Minor
Igneous > Hypabyssal > Felsic-hypabyssal > Hypabyssal-rhyolite (Dike or sill)
Igneous > Hypabyssal > Felsic-hypabyssal > Hypabyssal-dacite (Pluton)
Incidental
Igneous > Hypabyssal > Mafic-hypabyssal > Hypabyssal-andesite (Pluton)
Igneous > Hypabyssal > Mafic-hypabyssal > Hypabyssal-basalt (Pluton)
Map references
Jennings, C.W., Strand, R.G., and Rogers, T.H., 1977, Geologic map of California: California Division of Mines and Geology, scale 1:750,000.
Unit references
Luyendyk, B.P., Gans, P., and Kamerling, M.J., 1998, 40Ar/39Ar geochronology of Southern California Neogene volcanism. AAPG Bulleting, v. 82, p. 852 (abstract)
Stanley, R.G., Wilson, D.S., and McCrory, P.A., 2000, Locations and ages of middle Tertiary volcanic centers in coastal California: U.S. Geological Survey Open-File Report 00-154, 27 p., url http://geopubs.wr.usgs.gov/open-file/of00-154/
Jennings, C.W., Strand, R.G., and Rogers, T.H., 1977, Geologic map of California: California Division of Mines and Geology, scale 1:750,000.
Counties San Luis Obispo