Alkalic intrusive rocks

Sills, dikes, stocks, and irregular intrusions of porphyritic or aphanitic camptonite, shonkinite, and. nepheline syenite or phonolite. Potassium-argon ages of 32 to 35 Ma obtained on camptonite and nepheline syenite (Snavely and others, 1976c; Fiebelkorn and others, 1983)
State Oregon
Name Alkalic intrusive rocks
Geologic age Eocene to Oligocene
Lithologic constituents
Major
Igneous > Plutonic > Foidal-syenitic > Nepheline-syenite (Dike or sill, Stock or pipe)
Igneous > Plutonic > Syenitic > Syenite (Dike or sill, Stock or pipe)
Incidental
Igneous > Plutonic > Dioritic > Diorite (Dike or sill, Stock or pipe)
References

Walker, G.W. and MacLeod, N.S., 1991, Geologic map of Oregon: U.S. Geological Survey, scale 1:500,000.

NGMDB product
Counties Curry - Lincoln - Polk