1. Mineral Resources
  2. Online Spatial Data
  3. Geology
  4. by state
  5. Oregon

Basalt and basaltic andesite

XML
JSON
Shapefile
Flows, flow breccia, and pyroclastic deposits. Flows are aphanitic to finely crystalline, commonly diktytaxitic, and aphyric to porphyritic. Textures are mostly intergranular grading to intersertal; some andesite flows are finely trachytic and a few basalt flows are subophitic. Phenocrysts, mostly unaltered, include bytownite and labradorite, olivine, calcic augite, and hypersthene. Flows and breccia form shields, lava cones, and valley fill; in places greatly dissected and modified by fluvial erosion. Includes Boring Lava of Trimble (1963) and Hampton (1972) and Battle Ax Basalts of Thayer (1936). Potassium-argon ages from this unit range from about 1.2 to 3.9 Ma; in places difficult to distinguish from youngest flows of unit Trb
State Oregon
Name Basalt and basaltic andesite
Geologic age Pliocene to Pleistocene
Lithologic constituents
Major
Igneous > Volcanic > Mafic-volcanic > Basalt (Pyroclastic, Flow, Volcaniclastic-volcanic breccia)
Igneous > Volcanic > Mafic-volcanic > Basaltic-andesite (Pyroclastic, Flow, Volcaniclastic-volcanic breccia)
References

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

Trimble, D.E., 1963, geology of Portland, Oregon, and adjacent areas: U.S. Geological Survey Bulletin 1119, 110 p.

https://pubs.er.usgs.gov/publication/b1119

Hampton, E.R., 1972, Geology and groundwater of the Molalla-Salem area, northern Willamette Valley, Oregon: U.S. Geological Survey Water-Supply Paper 1997, 83 p.

https://pubs.er.usgs.gov/publication/wsp1997
NGMDB product
Counties Clackamas - Crook - Deschutes - Douglas - Harney - Hood River - Jackson - Jefferson - Klamath - Lake - Lane - Linn - Malheur - Marion - Multnomah - Wasco - Washington