Mafic intrusions (Oligocene) (ORTi;0)

State	Oregon
Name	Mafic intrusions (Oligocene)
Geologic age	Oligocene
Original map label	Ti
Primary rock type	gabbro
Secondary rock type	granitoid
Other rock types
Lithologic constituents	Major Igneous > Plutonic > Gabbroic > Gabbro (Dike or sill) Minor Igneous > Plutonic > Granitic (Dike or sill)
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. Snavely, P.D., Jr., MacLeod, N.S., Wagner, H.C., and Rau, W.W., 1976a, Geologic map of the Cape Foulweather and Euchre Mountain quadrangles, Lincoln County, Oregon: U.S. Geological Survey Miscellaneous Investigations Series Map I-868, scale 1:62,500. [http://pubs.er.usgs.gov/publication/i868] Snavely, P.D., Jr., MacLeod, N.S., Wagner, H.C., and Rau, W.W., 1976c, Geologic map of the Waldport and Tidewater quadrangles, Lincoln, Lane, and Benton Counties, Oregon: U.S. Geological Survey Miscellaneous Investigations Series Map I-866, scale 1:62,500. [http://pubs.er.usgs.gov/publication/i866] Fiebelkorn, R.B., Walker, G.W., Macleod, N.S., McKee, E.H., and Smith, J.G., 1983, Index to K-Ar determinations for the State of Oregon: Isochron/West, no. 37, p. 3-60.
Geographic coverage	Benton - Clatsop - Douglas - Lane - Lincoln - Marion - Polk - Tillamook - Washington - Yamhill