Basalt and andesite intrusions

Sills, plugs and dikes of basaltic andesite, basalt, and andesite. Mostly represents feeders, exposed by erosion, for flows and flow breccias of units Tba and Trb. Includes a few dikes of hornblende and plagioclase porphyritic andesite, commonly altered, and aphyric basaltic andesite that probably were feeders for parts of unit Tub
State Oregon
Name Basalt and andesite intrusions
Geologic age Oligocene(?) to Pliocene
Lithologic constituents
Major
Igneous > Hypabyssal > Mafic-hypabyssal > Hypabyssal-andesite (Dike or sill, Stock or pipe)
Igneous > Hypabyssal > Mafic-hypabyssal > Hypabyssal-basaltic-andesite (Dike or sill, Stock or pipe)
Igneous > Hypabyssal > Mafic-hypabyssal > Hypabyssal-basalt (Dike or sill, Pyroclastic-tuff)
References

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

NGMDB product
Counties Clackamas - Douglas - Hood River - Jackson - Jefferson - Klamath - Lane - Linn - Malheur - Marion - Multnomah