Mafic vent complexes (Pleistocene, Pliocene, and Miocene?) (ORQTmv;0)

Plugs, dikes, and related near-vent flows, breccia, cinders, and agglutinate of basalt, basaltic andesite, and andesite; commonly in the form of either little-modified lava cones or partly eroded piles of reddish, iron-stained thin flows and fragmental ejecta cut by mafic intrusions. May also include rocks of late Miocene(?) age

State	Oregon
Name	Mafic vent complexes (Pleistocene, Pliocene, and Miocene?)
Geologic age	Late Miocene to Pleistocene
Original map label	QTmv
Comments	Unit is in a north-south zone along crest of Cascades and includes Newberry volcano.
Primary rock type	basalt
Secondary rock type	andesite
Other rock types
Lithologic constituents	Major Igneous > Hypabyssal > Mafic-hypabyssal > Hypabyssal-basaltic-andesite (Dike or sill) Igneous > Volcanic > Mafic-volcanic > Basaltic-andesite (Flow) Minor Igneous > Volcanic > Mafic-volcanic > Andesite (Pyroclastic, cinder cone) Igneous > Volcanic > Mafic-volcanic > Basalt (Pyroclastic, cinder cone) Igneous > Volcanic > Mafic-volcanic > Basaltic-andesite (Pyroclastic, cinder cone) Igneous > Hypabyssal > Mafic-hypabyssal > Hypabyssal-andesite (Dike or sill) Igneous > Hypabyssal > Mafic-hypabyssal > Hypabyssal-basalt (Dike or sill) Igneous > Volcanic > Mafic-volcanic > Andesite (Flow) Igneous > Volcanic > Mafic-volcanic > Basalt (Flow)
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. Waters, A.C., 1968, Reconnaissance geologic map of the Madras quadrangle, Jeffereson and Wasco Counties, Oregon" U.S. Geological Survey Miscellaneous Geological Investigations Map I-555, scale 1;125,000. [http://pubs.er.usgs.gov/publication/i555]
Geographic coverage	Clackamas - Crook - Deschutes - Douglas - Hood River - Jackson - Jefferson - Klamath - Lane - Linn - Marion - Multnomah - Wasco