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Volcanic rocks (Jurassic)

Lava flows, flow breccia, and agglomerate dominantly of plagioclase, pyroxene, and hornblende porphyritic and aphyric andesite. Includes flow rocks that range in composition from basalt to rhyolite as well as some interlayered tuff and tuffaceous sedimentary rocks. Commonly metamorphosed to greenschist facies; locally foliated, schistose or gneissic. Includes the Rogue Formation and volcanic rocks commonly assigned to the Galice Formation (Wells and Walker, 1953; Wells and Peck, 1961). Considered to be accreted island-arc terrane
State Oregon
Name Volcanic rocks (Jurassic)
Geologic age Late Jurassic
Primary rock type andesite
Secondary rock type basalt
Other rock types felsic volcanic rock; mudstone; chert
Lithologic constituents
Major
Igneous > Volcanic > Mafic-volcanic > Andesite (Flow)
Minor
Igneous > Volcanic > Mafic-volcanic > Basalt (Flow)
Igneous > Volcanic > Felsic-volcanic (Flow)
Igneous > Volcanic > Mafic-volcanic > Andesite (Volcaniclastic, volcanic breccia)
Incidental
Igneous > Volcanic > Felsic-volcanic (Pyroclastic)
Sedimentary > Clastic > Mudstone (Bed)
Sedimentary > Chemical > Chert (Bed)
Map references
Walker, G.W. and MacLeod, N.S., 1991, Geologic map of Oregon: U.S. Geological Survey, scale 1:500,000.
Unit references
Walker, G.W. and MacLeod, N.S., 1991, Geologic map of Oregon: U.S. Geological Survey, scale 1:500,000.
Irwin, W.P., 1994, Geologic map of the Klamath Mountains, California and Oregon: U.S. Geological Survey Miscellaneous Investigations Series Map I-2148, scale 1:500,000.
Wells, F.G. and Peck, D.L., 1961, Geologic map of Oregon west of the 121st meridian: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-325, scale 1:500,000.
Wells, F.G., and Walker, G.W., 1953, Geology of the Galice quadrangle, Oregon: U.S. Geological Survey Geologic Quadrangle Series GQ-25, scale 1:62,500.
Counties Coos - Curry - Douglas - Jackson - Josephine