Date File Created Name of Creator 4/16/06 Rich Gaschnig GeoRef Data 2004-068538 DN GeoRef TI "The Cougar Point Tuff; implications for thermochemical zonation andlongevity of high-temperature, large-volume silicic magmas of theMiocene Yellowstone Hotspot" AU "Cathey, Henrietta E; Nash, Barbara P" AF "University of Utah, Department of Geology and Geophysics, Salt LakeCity, UT, United States USA" SO "Journal of Petrology, vol.45, no.1, pp.27-58, Jan 2004" IS 0022-3530 CD JPTGAD DE Bruneau-Jarbidge volcanic center; Cenozoic; Cougar Point Tuff;geochemistry; high temperature; hot spots; Idaho; igneous rocks;lithogeochemistry; magmas; Miocene; Neogene; Owyhee County Idaho;plate tectonics; pyroclastics; rhyolite tuff; rhyolites; temperature;Tertiary; thermochemical properties; tuff; United States; volcanicrocks; Yellowstone Hot Spot; zoning AB "The 12.7-10.5 Ma Cougar Point Tuff in southern Idaho, USA, consists of10 large-volume <10 super 2 -10 super 3 km super 3 each,high-temperature 800-1000 degrees C, rhyolitic ash-flow tuffserupted from the Bruneau-Farbidge volcanic center of the Yellow-stonehotspot. These tuffs provide evidence for compositional and thermalzonation in pre-eruptive rhyolite magma, and suggest the presence of along-lived reservoir that was tapped by numerous large explosiveeruptions. Pyroxene compositions exhibit discrete compositional modeswith respect to Fe and Mg that define a linear spectrum punctuated byconspicuous gaps. Airfall glass compositions also cluster into modes,and the presence of multiple modes indicates tapping of differentmagma volumes during early phases of eruption. Equilibrium assemblagesof pigeonite and augite are used to reconstruct compositional andthermal gradients in the pre-eruptive reservoir. The recurrence ofidentical compositional modes and of mineral pairs equilibrated athigh temperatures in successive eruptive units is consistent with thepersistence of their respective liquids in the magma reservoir.Recurrence intervals of identical modes range from 0.3 to 0.9 Myr andsuggest possible magma residence times of similar duration. Eruptionages, magma temperatures, Nd isotopes, and pyroxene and glasscompositions are consistent with a long-lived, dynamically evolvingmagma reservoir that was chemically and thermally zoned and composedof multiple discrete magma volumes." LA English FE "References: 57; illus. incl. charts, 9 tables, sketch map" PY 2004 PT Serial; Analytic CP United Kingdom GBR LL "Latitude:N420000,N434000 Longitude:W1150400,W1170200" CL "02C Geochemistry of rocks, soils, and sediments; 05A Igneous andmetamorphic petrology" CY "GeoRef, Copyright 2004, American Geological Institute." UD 200420 DO 10.1093/petrology/egg081 AN 2004-068538 Sample Data Item Sc Co Br Cs La Ce Nd Sm Eu Tb Yb Lu Hf Ta Th U Fe2O3 CaO Ti Mn Zn Rb Sr Y Zr Nb Ba Volcanic_Field Rock_Class Sample_Description source_proximity Rock_Type Age Max_age Min_age Age LatDD LongDD Loc_prec Material State Units ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm wt % wt % ppm ppm ppm ppm ppm ppm ppm ppm ppm Ma Ma Ma Ma DD DD Method 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 3 3 3 4 5 5 Sample Name tc89-12 1.6 1.8 3.8 4.1 101 174 61 10.4 0.4 2 5.25 0.75 8.4 2.9 35 8.9 1.31 0.49 930 170 60 227 7 50 215 48 120 "Cougar Point Tuff, unit 1 unit III by the old nomenclature" airfall tuff distal volcanic 12.67 12.7 12.64 41.96 -115.66 0.1 whole rock NV 95cpt/sr27 1.5 2.4 3.9 6 84 154 60 10.5 0.23 2.1 7.05 0.92 8.3 4.2 39 11.7 1.33 0.52 760 145 54 279 5 88 216 58 45 "Cougar Point Tuff, unit 1 unit III by the old nomenclature" ash-flow tuff basal vitrophyre proximal volcanic 12.67 12.7 12.64 41.96 -115.66 0.1 whole rock NV 95cpt/sr81 1.6 3 2.5 1.6 46 88 33 5.84 0.27 1.2 3.48 0.47 5.1 1.8 21 6.6 1.13 0.3 887 72 154 124 32 34 245 32 333 "Cougar Point Tuff, unit 1 unit III by the old nomenclature" ash flow tuff upper interior of unit proximal volcanic 12.67 12.7 12.64 41.96 -115.66 0.1 whole rock NV tc89-18a 2 2.5 2.7 3.5 88 154 58 10.1 0.72 1.9 5.09 0.74 9.8 1.9 29 7.7 1.63 0.53 1220 185 50 200 27 55 295 45 520 "Cougar Point Tuff, unit 2 unit V by the old nomenclature" airfall tuff distal volcanic 12.07 12.11 12.03 41.94 -115.42 0.1 whole rock NV 95cpt/j83 2.3 1.2 3.6 4 97 175 64 11 0.71 2.1 6.34 0.88 11 2.7 34 9.3 1.7 0.66 1228 181 49 208 31 66 377 43 561 "Cougar Point Tuff, unit 2 unit V by the old nomenclature" ash-flow tuff basal vitrophyre proximal volcanic 12.07 12.11 12.03 41.94 -115.42 0.1 whole rock NV 95cpt/j85 4.2 3.2 3.1 4.8 80 144 56 9.7 1.22 1.6 5.11 0.72 11 2.9 32 8 2.14 1 1883 254 40 193 56 54 452 40 878 "Cougar Point Tuff, unit 2 unit V by the old nomenclature" ash-flow tuff upper vitrophyre proximal volcanic 12.07 12.11 12.03 41.94 -115.42 0.1 whole rock NV brv93-429 3.8 3 2.9 4 85 151 58 10.1 1.16 2.1 5.41 0.74 12 3.2 32 8.7 1.66 0.55 1510 205 33 199 32 50 365 40 740 "Cougar Point Tuff, unit 3 unit VII by the old nomenclature" airfall tuff distal volcanic 11.8 41.96 -115.66 0.1 whole rock NV 95cpt/sr57 4 2.7 2.3 3.9 79 144 55 9.46 0.96 1.3 5 0.7 12 2.9 32 8.4 1.83 0.62 1780 187 31 200 39 60 432 41 804 "Cougar Point Tuff, unit 3 unit VII by the old nomenclature" ash-flow tuff basal vitrophyre proximal volcanic 11.8 41.96 -115.66 0.1 whole rock NV 95cpt/sr61 4.3 3.1 1.4 4.1 78 143 55 9.49 0.9 1.3 4.84 0.7 12 2.5 30 8.2 2.18 0.99 2004 255 37 186 53 54 474 37 886 "Cougar Point Tuff, unit 3 unit VII by the old nomenclature" ash-flow tuff upper vitrophyre proximal volcanic 11.8 41.96 -115.66 0.1 whole rock NV tc89-25a 2.6 2.5 2.2 3.4 82 144 52 9.02 0.94 1.8 4.64 0.68 10.8 2.1 31 8.2 1.61 0.5 1330 165 38 195 24 49 330 38 580 "Cougar Point Tuff, unit 4 unit IX by the old nomenclature" airfall tuff distal volcanic 11.59 41.96 -115.66 0.1 whole rock NV 95cpt/sr63 3.9 3.6 1.8 4.4 82 152 56 9.61 0.84 1.3 5.01 0.71 12 2.6 32 8.7 2.18 1.35 1830 257 36 180 45 54 519 41 712 "Cougar Point Tuff, unit 4 unit IX by the old nomenclature" ash-flow tuff basal vitrophyre proximal volcanic 11.59 41.96 -115.66 0.1 whole rock NV 95cpt/sr66 3.2 2.7 2.6 4 88 160 58 10.3 0.61 1.5 5.6 0.74 11 2.8 36 10 1.77 0.54 1474 174 34 203 26 59 401 41 547 "Cougar Point Tuff, unit 4 unit IX by the old nomenclature" ash-flow tuff upper vitrophyre proximal volcanic 11.59 41.96 -115.66 0.1 whole rock NV 95cpt/sr38 3 2 2.8 2.6 40 76 26 4.45 1.72 1 4.11 0.61 13 2.9 20 8.6 2.44 0.61 2026 138 46 172 53 54 747 43 1401 "Cougar Point Tuff, unit 5 unit X by the old nomenclature" ash-flow tuff lower interior of unit proximal volcanic 11.4 41.96 -115.66 0.1 whole rock NV 95cpt/sr39 3.3 2.8 2.2 2.5 42 202 27 4.77 2.25 0.7 4.55 0.68 11 2.5 18 4.8 2.63 0.67 1853 147 45 150 65 45 788 41 1749 "Cougar Point Tuff, unit 5 unit X by the old nomenclature" ash-flow tuff upper interior of unit proximal volcanic 11.4 41.96 -115.66 0.1 whole rock NV brv93-431a 2.7 2.6 3.7 3.8 93 171 64 11.2 0.95 1.8 5.95 0.87 10 2.5 34 8.9 1.63 0.55 1180 185 42 191 21 56 325 39 480 "Cougar Point Tuff, unit 6 unit XI by the old nomenclature" airfall tuff distal volcanic 11.31 41.96 -115.66 0.1 whole rock NV 95cpt/sr67 2.9 2.3 3.7 4.1 89 163 62 10.7 0.72 1.4 5.82 0.78 11 3 34 8.5 1.99 0.54 1430 178 49 192 19 63 419 44 493 "Cougar Point Tuff, unit 6 unit XI by the old nomenclature" ash-flow tuff basal vitrophyre proximal volcanic 11.31 41.96 -115.66 0.1 whole rock NV 95cpt/sr75 2.6 2 2.2 3.7 87 160 61 10.5 0.61 1.4 5.43 0.74 11 3 32 8.4 1.81 0.54 1569 194 48 195 21 61 450 43 555 "Cougar Point Tuff, unit 6 unit XI by the old nomenclature" ash-flow tuff upper interior of unit proximal volcanic 11.31 41.96 -115.66 0.1 whole rock NV wjr93-538 3.7 2.7 2.3 3.4 81 145 56 9.48 0.91 1.9 4.92 0.7 12 2.5 30 8.3 1.9 0.57 1710 195 33 178 40 48 415 38 1000 "Cougar Point Tuff, unit 7 unit XII by the old nomenclature" airfall tuff distal volcanic 11.19 41.94 -115.42 0.1 whole rock NV 95cpt/hg98 5.9 5.2 1.5 3.9 75 136 53 8.78 0.88 1.6 4.87 0.69 17 1.8 29 7.3 2.99 1.23 2599 320 49 162 60 46 530 37 1030 "Cougar Point Tuff, unit 7 unit XII by the old nomenclature" ash-flow tuff basal vitrophyre proximal volcanic 11.19 41.94 -115.42 0.1 whole rock NV 95cpt/hg97.5 4 3.5 1.4 3.4 77 138 52 8.88 1.22 1.5 4.75 0.68 13 3.1 28 8 "Cougar Point Tuff, unit 7 unit XII by the old nomenclature" ash-flow tuff upper vitrophyre proximal volcanic 11.19 41.94 -115.42 0.1 whole rock NV 95cpt/j10 6.5 6.7 3.1 2.7 81 147 54 9.2 0.96 1.6 5.53 0.77 15 2.7 30 8.3 2.96 0.98 2647 308 46 165 43 47 572 37 983 "Cougar Point Tuff, unit 7 unit XII by the old nomenclature" ash-flow tuff basal vitrophyre proximal volcanic 11.19 41.94 -115.42 0.1 whole rock NV 95cpt/j16 4.6 2.9 2.4 3.7 83 152 57 9.84 0.93 1.5 5.28 0.75 14 2.7 32 8.6 2.81 0.92 2489 300 44 165 42 49 552 37 1002 "Cougar Point Tuff, unit 7 unit XII by the old nomenclature" ash-flow tuff upper vitrophyre proximal volcanic 11.19 41.94 -115.42 0.1 whole rock NV tc89-31a 2.3 1.8 3 3.5 96 174 68 12.4 0.75 1.9 6.75 0.95 11 2.7 31 8.2 1.84 0.57 1120 180 63 184 24 76 350 38 700 "Cougar Point Tuff, unit 8 unit XIII by the old nomenclature" airfall tuff distal volcanic 10.94 10.97 10.91 42.01 -115.63 0.1 whole rock ID 95cpt/hg96 2.9 1.9 2.5 4 102 187 74 13.1 1.58 2.7 7.04 0.99 13 3.4 33 9.3 2.1 0.64 1654 205 78 183 24 72 493 48 588 "Cougar Point Tuff, unit 8 unit XIII by the old nomenclature" ash-flow tuff basal vitrophyre proximal volcanic 10.94 10.97 10.91 42.01 -115.63 0.1 whole rock ID 95cpt/hg90 3.1 1.8 3.1 4 96 176 67 12 1.3 2.4 6.93 0.99 14 4 31 8.5 2.34 0.73 1812 183 69 168 36 63 555 49 745 "Cougar Point Tuff, unit 8 unit XIII by the old nomenclature" ash-flow tuff upper vitrophyre proximal volcanic 10.94 10.97 10.91 42.01 -115.63 0.1 whole rock ID brv95-840 3 2.9 3.1 3.4 84 151 57 10.2 1.09 1.5 5.59 0.74 12 2.6 29 8.3 1.96 0.59 1656 215 37 179 44 53 434 39 981 "Cougar Point Tuff, unit 9b unit XVb by the old nomenclature" airfall tuff distal volcanic 10.45 42.01 -115.63 0.1 whole rock ID 95cpt/hg89 3.4 3.3 2 3.6 80 147 57 9.7 0.71 1.7 5.13 0.78 12 3.1 29 7.9 2.14 0.85 1724 207 41 169 48 54 443 38 954 "Cougar Point Tuff, unit 9b unit XVb by the old nomenclature" ash-flow tuff basal vitrophyre proximal volcanic 10.45 42.01 -115.63 0.1 whole rock ID 95cpt/hg87 5.7 5.2 1.8 3.6 77 141 53 9.42 1.46 1.7 5.49 0.75 13 2.7 27 7.6 2.88 1.54 2184 320 48 145 84 46 595 35 1090 "Cougar Point Tuff, unit 9b unit XVb by the old nomenclature" ash-flow tuff upper vitrophyre proximal volcanic 10.45 42.01 -115.63 0.1 whole rock ID ejr93-532a 2.7 2.1 3.1 4.2 92 171 68 12.1 1.29 2.3 6.54 0.88 14 2.8 30 8.4 2.14 0.67 1610 240 63 173 39 59 460 44 1020 "Cougar Point Tuff, unit 9j unit XVj by the old nomenclature" airfall tuff distal volcanic 10.45 42.02 -115.36 0.1 whole rock ID 95cpt/mhs2 4.4 3.9 2.8 3.8 87 160 65 11.7 1.41 1.9 6.44 0.93 15 3.2 29 8 3 0.87 2393 281 75 162 45 61 577 45 1208 "Cougar Point Tuff, unit 9j unit XVj by the old nomenclature" ash-flow tuff basal vitrophyre proximal volcanic 10.45 42.02 -115.36 0.1 whole rock ID 95cpt/mhs6 5.2 3.7 2.5 3.3 84 158 64 11.5 1.6 2 6.54 0.92 14 2.9 28 8.1 3.25 0.89 2200 301 72 157 55 61 571 42 1314 "Cougar Point Tuff, unit 9j unit XVj by the old nomenclature" ash-flow tuff upper vitrophyre proximal volcanic 10.45 42.02 -115.36 0.1 whole rock ID Method Data 1 INAA 466 2 XRF 459 3 REG_COR 1998-025813 Ar-Ar dates 4 Strat 57 interpolated from Perkins et al. 1998 Ar-Ar dates 5 PERCOM 1998-025813 Reference data georef# 1998-025813 TI "Sequence, age, and source of silicic fallout tuffs in middle to late Miocene basins of the northern Basin and Range Province." AU Perkins-Michael-E; Brown-Francis-H; Nash-William-P; McIntosh-William; Williams-S-K AF "University of Utah, Department of Geology and Geophysics, Salt Lake City, UT, United States" SO "Geological Society of America Bulletin. 110; 3, Pages 344-360. 1998." PB "Geological Society of America GSA. Boulder, CO, United States. 1998." CP United-States PY 1998 LA English AB "The latest Cenozoic <6 Ma ash beds in the western United States have been intensively studied for several decades. The more widespread of these ash beds are well-documented event horizons that are of great value in studies of the timing and pace of geological, climatological, and biological events throughout the region. Because explosive volcanism was not restricted to latest Neogene time in this region, many older ash beds are likely to prove as useful as younger beds as event horizons, once they are located, characterized, and dated. As a first step in developing a useful chronology of older Cenozoic ash beds in the western United States, we have sampled and analyzed silicic fallout tuffs in middle to late Miocene sedimentary basins across the northern Basin and Range province. The northern Basin and Range basins, ideally situated in the vicinity of major coeval silicic volcanic centers, contain numerous relatively unaltered, silicic fallout tuffs. We have correlated tuffs between all sampled sections on the basis of glass shard composition. The composite stratigraphic sequence established by the correlations contains more than 200 individual tuffs, including 59 widely distributed tuffs termed correlative tuffs. The tuffs vary widely in composition, but most are in one of two compositional groups: gray metaluminous vitric tuffs Gm tuffs or white metaluminous vitric tuffs Wm tuffs. Distribution patterns, compositional characteristics, and correlation with ash-flow tuffs show that the source for most Gm tuffs was the Snake River Plain volcanic province along the northern edge of the northern Basin and Range, and the source for most Wm tuffs was the southwestern Nevada volcanic field in the southern part of the northern Basin and Range. The northern Basin and Range tuffs range in age from ca. 16-6 Ma. The ages of individual tuffs are determined variously by direct isotopic dating, by correlation to previously dated fallout and ash-flow tuffs, or by interpolation age estimation. Ages for most tuffs are known to within 0.25 m.y. 1sigma or less and for many tuffs to within 0.1 m.y. or less. The sequence and ages of tuffs established in this study provide insights into the evolution of the northern Basin and Range basins and patterns of explosive volcanism in coeval volcanic centers, and contribute to the development of a high-resolution stratigraphy and chronology of coeval sedimentary deposits throughout the western United States." DE acidic-composition; Basin-and-Range-Province; basins-; Cenozoic-; correlation-; Idaho-; igneous-rocks; middle-Miocene; Miocene-; Neogene-; Nevada-; North-America; Oregon-; pyroclastics-; sedimentary-basins; sedimentary-rocks; sedimentation-; sedimentation-rates; spectra-; tephrochronology-; Tertiary-; tuff-; United-States; upper-Miocene; Utah-; volcanic-centers; volcanic-features; volcanic-rocks; volcaniclastics-; volcanism-; Western-U.S.; X-ray-fluorescence-spectra CC 12-Stratigraphy; 03-Geochronology DT Serial BL Analytic NN Includes 2 appendices. IL "Refs 79; illus. incl. 10 tables, sketch map." RF "GeoRef, Copyright 2002, American Geological Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States" IS 0016-7606 CO BUGMAF AN 1998-025813 UD 199810