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Mineral Resources On-Line Spatial Data

Sedimentary and volcanic rocks (Jurassic and Upper Triassic?)

Olive-drab, pale-brown, dark-gray, and black volcanic graywacke and siltstone; lesser conglomerate and slate, and minor limestone and chert. Includes more extensive outcrops of Triassic or Jurassic limestone at north base of Juniper Mountain in northern Malheur County and near Huntington in southeastern Baker County. Interlayers of silicic and intermediate volcanic rocks are rare. Locally metamorphosed to prehnite-pumpellyite and zeolite facies and in places to greenschist facies. Folded, sheared, and locally foliated. Includes the Weatherby Formation of Brooks (1979). Age is Late Triassic(?) and Early and Middle Jurassic (Sinemurian-Callovian)
StateOregon
NameSedimentary and volcanic rocks (Jurassic and Upper Triassic?)
Geologic ageLate Triassic? to Jurassic
Original map labelJTRsv
CommentsWeatherby Formation (OR186) along south side of Burnt River is largely massive metagraywacke and contains cannibalistic conglomerate and tabular slide blocks of serpentine-matrix melange as much as a few hundred meters long, presumably from the Baker terrane to the north. Weatherby Formation, formerly of the Olds Ferry terrane, was redefined as part of the Izee terrane (OR089). Unit includes igneous and metamorphic complex of Pueblo Mountains that contains schists which have protoliths of lava flows, tuffs, volcanogenic sediments, and plutons; Jurassic plutons are of quartz diorite, granodiorite, tonalite, and quartz monzonite (OR187); and lava flows are dominantly intermediate in composition and include felsic flows, flow breccia, tuff, agglomerate, and sedimentary rocks. Part of the complex may have formed in a magmatic arc setting; some of the rocks appear to have been deposited in a marine environment. Schists were more recently re-interpreted as a ductiley deformed plutonic complex. The complex underwent dynamothermal middle greenschist-facies metamorphism during late Jurassic and Early Cretaceous (OR187; OR188). Interpretations of the rock assemblage suggested that the protoliths of some of the rocks in this unit may be Paleozoic, possibly Lower Permian (OR189). The complex in the Pueblo Mountains is part of the Black Rock terrane (OR089). Not represented on State map (OR001), but present in area covered by La Grande 30' x 60' quadrangle (OR291), is the Mountain Home Metamorphic Complex, which consists of biotite schists of Yellow Jacket Road (Triassic-Jurassic), that have sedimentary and volcanic protoliths. May be metamorphosed equivalents to Late Triassic-Jurassic Hurwal Formation. Also occurs in Umatilla River Basin (OR292).
Primary rock typegraywacke
Secondary rock typesiltstone
Other rock typesconglomerate
Lithologic constituents
Major
Sedimentary > Clastic > Sandstone > Graywacke (Bed)
Minor
Metamorphic > Metasedimentary (Greenschist)
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.
Walker, G.W. and Repenning, C.A., 1965, Geologic map of Adel quadrangle, Lake, Harney, and Malheur Counties, Oregon: U.S. Geological Survey Miscellaneous Geologic Investigations Map I-446, scale 1:250,000.
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.
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.
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.
Brooks, H.C., 1979, Geologic map of the Huntington and part of the Olds Ferry quadrangles, Baker and Mlheur Counties, Oregon: Oregon Department of Geology and Mineral Industries Geologic Map Series, GMS-13, scale 1:62,500.
Wolff, E.N., 1965, The geology of the northern half of the Caviness quadrangle, Oregon: Eugene, University of Oregon, Ph.D. dissertation, 214 p.
Brooks, H.C., 2006, Preliminary geologic map of the Mormon Basin quadrangle, Baker County, Oregon: Oregon Department of Geology and Mineral Industries Open-File Map O-06-25, 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 Geologic Map Series GMS-28, scale 1:24,000.
Evans, J.G., Geologic map of the Dooley Mountain quadrangle, Baker County, Oregon: U.S. Geological Survey Geological Quadrangle GQ-1694, scale 1: 24,000.
Brooks, H.C., Ferns, M.L., and Avery, D.G., 1984, Geology and gold deposits of the southwest quarter of the Bates quadrangle, Grant County, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-35, scale 1:24,000.
Ferns, M.L., Brooks, H.C., and Wheeler, G.R., 1984, Geology and gold deposits of the Bates quadrangle, Grant County, Oregon: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-31, 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
Swisher, C.C., Ach, J.A., and Hart, W.K., 1990, Laser fusion 40Ar/39Ar dating of the type Steens Mountain Basalt, southeastern Oregon, and the age of the Steens aeromagnetic polarity transition [abs.]: EOS, Transactions of American Geophysical Union, v. 17, no. 43, p. 1,296.
Brooks, H.C., 1979, Geologic map of the Oregon part of the Mineral quadrangle: Oregon Department of Geology and Mineral Industries Geological Map Series GMS-12, scale 1:62,500.
Brooks, H.C., 1979a, Plate tectonics and the geologic history of the Blue Mountains: Oregon Geology, v. 41, no. 5, p. 71-80.
Brown, M.A., 1996, The pre-Tertiary geology, structural evolution, and geochronology of the Pueblo Mountains, Nevada-Oregon: Houston, Texas, Rice University, master's thesis, 75 p.
Roback, R.C., Vander Meulen, D.B., King, H.D., Plouff, Donald, Munts, S.R., and Willett, S.L., 1987, Mineral resources of the Pueblo Mountains Wilderness Study Area, Harney County, Oregon, and Humboldt County, Nevada: U.S. Geological Survey Bulletin 1740-B, 30 p.
Silberling, N.J., Jones, D.L., Blake, M.C., Jr., and Howell, D.G., 1987, Lithotectonic terrane map of the western conterminous United States: U.S. Geological Survey Miscellaneous Field Studies Map MF-1847-C, scale 1:2,500,000, 20 p.
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.
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.
Evans, J.G., unpub. mapping, 1994, Ladycomb Peak quadrangle, Harney County
Whitsun, N.W., 1988, Geochemical stratigraphy of the Dooley Rhyolite Breccia and Tertiary basalts in the Dooley Mountain quadrangle, Oregon: Portland, Oregon, Portland State University, master's thesis, 122 p.
Beeson, J.H., Geology of the southern half of the Huntington quadrangle, Oregon: Eugene, University of Oregon, master's thesis, 77 p.
Berry, N.J., 1956, Geology of the northeast quarter of the Huntington quadrangle, Oregon: Eugene, University of Oregon, master's thesis, 78 p.
Ferns, M.L., Madin, I.P., and Taubeneck, W.H., 2001, Reconnaissance geologic map of the La Grande 30' x 60' quadrangle, Baker, Grant, Umatilla, and Union Counties, Oregon: Oregon Department of Geology and Mineral Industries Reconnaissance Map Series RMS-1, 52 p., scale 1:100,000.
Ferns, M.L., McConnell, V.S., and Madin, I.P., in prep., Geology of the Umatilla River Basin, Morrow, Umatilla, and Union Counties, Oregon: Oregon Department of Geology and Mineral Industries Open-File Report, 66 p., scale 1:100,000.
Geographic coverageBaker - Grant - Harney - Malheur

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