Strawberry Volcanics

Flows and flow breccia of basalt, basaltic andesite, and andesite; includes restricted domal complexes and related flows and breccia of rhyolite and dacite (Thayer, 1957; Brown and Thayer, 1966). Potassium-argon ages are mostly in the range of 12 to 20 Ma (Robyn, 1977; Fiebelkorn and others, 1983)
State Oregon
Name Strawberry Volcanics
Geologic age Miocene to Pliocene
Lithologic constituents
Major
Igneous > Volcanic > Mafic-volcanic > Andesite (Flow)
Igneous > Volcanic > Mafic-volcanic > Basalt (Flow)
Igneous > Volcanic > Mafic-volcanic > Basaltic-andesite (Flow)
Minor
Igneous > Volcanic > Felsic-volcanic > Dacite (Dome, Flow)
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Dome, Flow)
Comments The large area of Tstv shown on the State geologic map (OR001) northwest of Vale is a continuation of lower and middle Miocene rock units mapped to the south in the Vale 30'x 60' quadrangle (OR007) and includes rhyolite of Cottonwood Mountain, Hunter Creek Basalt, a thick underlying basalt and basaltic andesite sequence that may be equivalent to the basalt of Malheur Gorge, and intercalated sedimentary and pyroclastic rocks (Evans, unpub. mapping 1994, Hope Butte and Swede Flat 7.5' quadrangles).
References

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

Ferns, M.L., Evans, J.G., and Cummings, M.L., 1993a, Geologic map of the Mahogany Mountain 30 x 60 minute quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-78, scale 1:100,000.

Ferns, M.L., Brooks, H.C., Evans, J.G., and Cummings, M.L., 1993b, Geologic map of the Vale 30 x 60 minute quadrangle, Malheur County Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-77, scale 1:100,000.

Brown, C.E. and Thayer, T.P., 1966, Geologic map of the Canyon City quadrangle, northeastern Oregon: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-447, scale 1:250,000.

https://pubs.er.usgs.gov/publication/i447

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.

Thayer, T.P., 1957, Some relations of later Tertiary volcanology and structure in eastern Oregon, in Volcanologia del Cenozoico: 20th International Geology Conference, Mexico, D.F., 1956, v.1, p. 231-245.

Robyn, T.L., 1977, Geology and petrology of the Strawberry Volcanics, NE Oregon: Eugene, University of Oregon, Ph.D. dissertation, 224 p.

Brooks, H.C., McIntyre, J.R., and Walker, G.W., 1976, Geology of the Oregon part of the Baker 1o by 2o quadrangle: Oregon Department of Geology and Mineral Industries Geologic Map Series GMS-7, scale 1:250,000.

Walker, G.W., 1977, Geologic map of Oregon east of the 121st meridian: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-902, scale 1:500,000.

https://pubs.er.usgs.gov/publication/i902

Wolff, E.N., 1965, The geology of the northern half of the Caviness quadrangle, Oregon: Eugene, University of Oregon, Ph.D. dissertation, 214 p.

Ferns, M.L., Brooks, H.C., and Avery, D.G., 1983, Geology and gold deposits map of the Greenhorn quadrangle, Baker and Grant Counties, Oregon: Oregon Department of Geology and Mineral Industries Geologic Map Series GMS-28, scale 1:24,000.

Brooks, H.C., Ferns, M.L., Wheeler, G.R., and Avery, D.G., 1983, Geology and gold deposits map of the northeast quarter of the Bates quadrangle, Baker and Grant Counties, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-29, scale 1:24,000

Brooks, H.C., Ferns, M.L., Coward, R.I., Paul, E.K., and Nunlist, M., 1982, Geology and gold deposits map of the Bourne quadrangle, Baker and Grant Counties, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-19, scale 1:24,000.

Brooks, H.C. and Ferns, M.L., 1979, Geologic map of the Bullrun Rock quadrangle, Baker and Grant Counties, Oregon: Oregon Department of Geology and Mineral Industries Open-File Map O-79-6, scale 1:24,000.

Evans, J.G., Geologic map of the Beaverdam Creek quadrangle, Baker County, Oregon: U.S. Geological Survey Miscellaneous Field Studies Map MF-2299, scale 1:24,000.

https://pubs.er.usgs.gov/publication/mf2299

Evans, J.G., 1993, Geologic map of the Brannan Gulch quadrangle, Baker County, Oregon: U.S. Geological Survey Geological Quadrangle GQ-1744, scale 1:24,000.

https://pubs.er.usgs.gov/publication/gq1744

Evans, J.G., 1993, unpub. mapping, Unity Reservoir quadrangle, Baker County Oregon.

Evans, J.G., 1994, unpub. mapping, Hereford quadrangle, Baker County, Oregon.

Prostka, H.J., 1968, Geologic map of the Ironside 15' quad, Oregon: Oregon Department of Geology and Mineral Industries, scale 1:62,500.

Brooks, H.C., Ferns, M.L., Nusbaum, R.L., and Kovich, P.M., 1979, Geologic map of the Rastus Mountain quadrangle, Baker and Grant Counties, Oregon: Oregon Department of Geology and Mineral Industries Open-File Map O-79-7, scale 1:24,000.

Ferns, M.L., Brooks, H.C., and Avery, D.G., 1983, Geology and gold deposits map of the Greenhorn Quadrangle, Baker and Grant Counties, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-28, scale 1:24,000.

Thayer, T.P., Brown, C.E., and Hay, R.I., 1967, Preliminary geologic map of the Prairie City quadrangle, Grant County, Oregon: U.S. Geological Survey Open-File Map, scale 1:62,500.

https://pubs.er.usgs.gov/publication/ofr67214

Wood, J.D., 1976, The geology of the Castle Rock area, Grant, Harney, and Malheur Counties, Oregon: Portland, Oregon, Portland State University, master's thesis, 89 p.

Reef, J.W., 1983, The Unity Reservoir rhyodacite, tuff-breccia and associated volcanic rocks, Baker County, Oregon: Pullman, Washington State University master's thesis, 128 p.

NGMDB product
Counties Baker - Grant - Harney - Malheur