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Lacustrine and fluvial deposits (Miocene)

Poorly to moderately consolidated, bedded silicic ash and pumicite, diatomite, tuffaceous sedimentary rocks, minor mudflow deposits, and some coarse epiclastic deposits. Vitroclastic material in some beds diagenetically altered to zeolites, secondary silica minerals, and clay minerals. In eastern Blue Mountains province vertebrate fossils indicate unit is mostly of late Miocene (Clarendonian) age, but may also include some rocks of middle Miocene (Barstovian) age. In High Lava Plains and northern Owyhee Upland provinces, vertebrate fossils indicate unit is partly late Miocene (Clarendonian), but probably is mostly middle Miocene (Barstovian) in age. Interfingers and grades laterally into unit Tmb. Includes lake and stream sediments and tuffaceous lake and stream deposits of Prostka (1962, 1967), Deer Butte Formation of Corcoran and others (1962) and Kittleman and others (1967), Juntura Formation of Shotwell and others (1963), some rocks originally assigned to the lower part of the (now obsolete) Danforth Formation of Piper and others (1939), and interbeds in upper part of Columbia River Basalt Group in northern Wallowa County
State Oregon
Name Lacustrine and fluvial deposits (Miocene)
Geologic age Miocene
Comments Includes Leslie Gulch Ash-Flow Tuff and Tuff of Spring Creek (OR173)
Primary rock type volcanic ash
Secondary rock type chemical
Other rock types mudflow; conglomerate; tuff
Lithologic constituents
Major
Igneous > Volcanic > Felsic-volcanic > Rhyolite (Pyroclastic, air fall)Also contains pumicite, diatomite, tuffaceous sedimentary rocks, mudflow deposits, and epiclastic deposits
Minor
Sedimentary > Chemical > Diatomite (Bed)
Sedimentary > Clastic > Conglomerate (Bed)
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.
Greene, R.C., Walker, G.W., and Corcoran, R.E., 1972, Geologic map of the Burns quadrangle, Oregon: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-680, scale 1:250,000.
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.
Shotwell, J.A., 1956, Hemphillian mammalian assemblage from northeast Oregon: Geological Society of America Bulletin, v. 67, p. 717-738.
Corcoran, R.E., Doak, R.A., Porter, P.W., Pritchett, F.I., and Privarsky, N.C., 1962, Geology of the Mitchell Butte quadrangle, Oregon: Oregon Department of Geology and Mineral Industries Geologic Map Series GMS-2, scale 1:125,000.
Piper, A.M., Robinson, T.W., and Park, C.F., Jr., 1939, Geology and ground-water resources of the Harney Basin, Oregon: U.S. Geological Survey Water-Supply Paper 842, 189 p.
Kittleman, L.R., Green, A.R., Hagood, A.R., Johnson, A.M., McMurray, J.M., Russell, R.G., and Weeden, D.A., 1965, Cenozoic stratigraphy of the Owyhee region, southeastern Oregon: Eugene, University of Oregon Museum of Natural History Bulletin 1, 45 p.
Kittleman, L.R., Green, A.R., Haddock, G.H., Hagood, A.R., Johnson, A.M., McMurray, J.M., Russell, R.G., and Weeden, D.A., 1967, Geologic map of the Owyhee region, Malheur County, Oregon: Eugene, University of Oregon Museum of Natural History Bulletion 8, scale 1:125,000
Prostka, H.J., 1962, Geology of the Sparta quadrangle, Oregon: Oregon Department of Geology and Mineral Industries Geologic Map Series GMS-1, scale 1:62,500.
Prostka, H.J., 1967, Preliminary geologic map of the Durkee quadrangle, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-3, scale 1, 62,500.
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., 1979, Reconnaissance geologic map of the Oregon part of the Grangeville quadrangle, Baker, Union, Umatilla, and Wallowa Counties, Oregon: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-1116, 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.
Evans, J.G., 1990a, Geology and mineral resources map of the Jonesboro Quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Geologic Map Series GMS-66, scale 1:24,000.
Evans, J.G., 1990b, Geology and mineral resources map of the South Mountain quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Geologic Map Series GMS-67, scale 1:24,000.
Ferns, M.L. and Ramp, Len, 1989, Geology and mineral resources map of the Grassy Mountain quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-57, scale 1:24,000.
Ferns, M.L., 1989, Geology and mineral resources map of the Owyhee Dam quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-55, scale 1:24,000.
Brown, D.E., 1982, Map showing geology and geothermal resources of the Vale East 71/2' quadrangle, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-21, scale 1:24,000.
Ferns, M.L. and Urbanczyk, K.M., 1990, Geology and mineral resources mao of the Mitchell Butte quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-61, scale 1:24,000.
Ferns, M.L. and Cummings, M.L., 1992, Geology and mineral resources map of The Elbow quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-62, scale 1:24,000.
Ferns, M.L. and O'Brien, J.P., 1992, Geology and mineral resources map of the Harper quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-69, scale 1:24,000.
Rytuba, J.J., Vander Meulen, D.B., Minor, S.A., and McKee, E.H., 1989, Geologic evolution of the Three Fingers caldera, Malheur County, Oregon [abs.]: Geological Society of America Anstracts with Pregrams, Cordilleran and Central Region Section Meeting, v. 21, no. 5, p. 138.
Evans, J.G. and Binger, G.B., 1998, Geologic map of the Little Black Canyon quadrangle, Malheur County, Oregon: U.S. Geological Survey Open-File Report 98-493, scale 1:24,000.
Evans, J.G. and Binger, G.B., 1998, Geologic map of the Alder Creek quadrangle, Malheur County, Oregon: U.S. Geological Survey Open-File Report 98-484, scale 1:24,000.
Evans, J.G. and Binger, G.B., 1999, Preliminary geologic map of the Skull Springs quadrangle, Malheur County, Oregon: U.S. Geological Survey Open-File Report 99-381, scale 1:24,000.
Barrash, Warren, Bond, J.G., Kauffmann, J.D., and Venkatakrishnan, Ramesh, 1980, Geology of the La Grande area, Oregon: Oregon Department of Geology and Mineral Industries Special Paper 6, 67 p., 4 maps, scale 1:24,000.
Evans, J.G. and Binger, G.B., 1998, Geologic map of the Shumway Reservoir quadrangle, Malheur County, Oregon: U.S. Geological Survey Open-File Report 98-138, scale 1:24,000.
Evans, J.G., 1996, Geologic map of the Monument Peak quadrangle, Malheur County, Oregon: U.S. Geological Survey Miscellaneous Field Studies Map MF-2317, scale 1:24,000.
Evans, J.G. and Keith, W.J., 1996, Geologic map of the Tims Peak quadrangle, Malheur County, Oregon: U. S. Geological Survey Miscellaneous Field Studies Map MF-2316, scale 1:24,000.
Cummings, M.L., 1993, Geologic map of the Sourdough Springs quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Open-File Report O-93-11, scale 1:24,000.
Evans, J.G., Rytuba, J.J., Binger, G.B., and Hooper, P.R., 1999, Preliminary geologic map of the Star Creek Reservoir quadrangle, Malheur County, Oregon: U.S. Geological Survey Open-File Report 99-583, scale 1:24,000.
Brooks, H.C., 1992, Preliminary geologic map of the Avery Creek quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Open-File Map O-92-16, scale 1:24,000.
Brooks, H.C., 1992, Preliminary geologic map of the Rufino Butte quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Open-File Map O-92-17, scale 1:24,000.
Brooks, H.C., 1993, Preliminary geologic map of the Copeland Reservoir quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral industries Open-File Map O-93-3, scale 1:24,000.
Ferns, M.L. and Evans, J.G., 1993c, Preliminary geologic map of the Rinehart Canyon quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Open-File Map O-93-5, scale 1: 24,000.
Ferns, M.L. and O'Brien, J.P., 1991, Preliminary geologic map of the Keeney Ridge quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Open-File Map O-91-3, scale 1:24,000.
Ferns, M.L. and O'Brien, J.P., 1992, Geology and mineral resources map of the Namorf quadrangle, Malheur County, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-74, scale 1:24,000.
McMurray, J.M., 1962, Geology of the Freezeout Mountain area, Malheur County, Oregon: Eugene, University of Oregon, master's thesis, 87 p.
Plumley, P.S., 1986, Volcanic stratigraphy and geochemistry of the Hole in the Ground area, Owyhee Plateau, southeastern Oregon: Moscow, University of Idaho, master's thesis, 161 p.
Camp, V.E., Ross, M.E., and Hanson, W.E., 2003, Genesis of flood basalts and Basin and Range volcanic rocks from Steens Mountain to the Malheur River Gorge, Oregon: Geological Society of America Bulletin, v. 115, no. 1, p. 105-128.
Johnson, J.A., Hooper, P.R., Hawkesworth, C.J., and Binger, G.B., 1998b, Geologic map of the Stemmler Ridge quadrangle, Malheur County, Oregon: U.S. Geological Survey Open-File Report 98-105, scale 1:24,000.
Vander Meulen, B.B., Rytuba, J.J., Grubensky, M.J., Vercoutere, T.L., and Minor, S.A., 1987, Geologic map of the Pelican Point quadrangle, Malheur County, Oregon: U.S. Geological Survey Miscellaneous Field Studies Map MF-1904, scale 1:24,000.
Vander Meulen, D.B., Rytuba, J.J., Vercoutere, T.L., and Minor, S.A., 1987, Geologic map of the Rooster Comb 7.5' quadrangle, Malheur County, Oregon: U.S. Geological Survey Miscellaneous Field Studies Map MF-1902C, scale 1:24,000.
Vercoutere, T.L., Vander Meulen, D.B., and Minor, S.A., 1987, Geologic map of the Diamond Butte quadrangle, Malheur County, Oregon: U.S. Geological Survey Miscellaneous Field Studies Map MF-1901, scale 1:24,000.
Weeden, D.A., 1963, Geology of the Harper area, Malheur County, Oregon: Eugene, University of Oregon, master's thesis, 94 p.
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.
Counties Harney - Malheur - Union - Wallowa