Date File Created Name of Creator 2/4/2009 Evan Reynolds GeoRef Data 2007-002412 DN GeoRef TI "Rhyodacites of Kulshan Caldera, north Cascades of Washington;post-caldera lavas that span the Jaramillo" AU "Hildreth, Wes; Lanphere, Marvin A; Champion, Duane E; Fierstein, Judy" AF "U. S. Geological Survey, Volcano Hazards Team, Menlo Park, CA, UnitedStates (USA)" SP "USGSOP, Non-USGS publications with USGS authors" SO "Journal of Volcanology and Geothermal Research, vol.130, no.3-4,pp.227-264, 29 Feb 2004" IS 0377-0273 CD JVGRDQ PB "Elsevier, Amsterdam, Netherlands (NLD)" DE absolute age; Ar/Ar; basement; breccia; calderas; Cascade Range;Cenozoic; chemical composition; collapse structures; Cordilleran icesheet; dates; dikes; domes; emplacement; eruptions; fluctuations;geochemistry; geomorphology; geophysical methods; geophysicalprofiles; geophysical surveys; gravity methods; gravity profiles;igneous rocks; intrusions; Jaramillo Subchron; K/Ar; Kulshan Caldera;landform evolution; lava flows; lower Pleistocene; magmatism;magnetization; Mount Baker; paleoenvironment; paleomagnetism;Pleistocene; Quaternary; remanent magnetization; rhyodacites; surveys;United States; volcanic features; volcanic rocks; volcanism;volcanoes; Washington AB "Kulshan caldera (4.5X8 km), at the northeast foot of Mount Baker, isfilled with rhyodacite ignimbrite (1.15 Ma) and postcaldera lavas andis only the third Quaternary caldera identified in the Cascade arc. Agravity traverse across the caldera yields a steep-sided, symmetrical,complete Bouguer anomaly of -16 mGal centered over the caldera.Density considerations suggest that the caldera fill, which is incisedto an observed thickness of 1 km, may be about 1.5 km thick and isflat-floored, overlying a cylindrical piston of subsided metamorphicrocks. Outflow sheets have been stripped by advances of theCordilleran Ice Sheet, but the climactic fallout (Lake Tapps tephra)is as thick as 30 cm some 200 km south of the caldera. Ten precalderaunits, which range in (super 40) Ar/ (super 39) Ar age from 1.29 to1.15 Ma, are dikes and erosional scraps that probably never amountedto a large edifice. A dozen postcaldera rhyodacite lavas and dikesrange in age from 1.15 to 0.99 Ma; rhyodacites have subsequently beenabsent, the silicic reservoir having finally crystallized. At least 60early Pleistocene intermediate dikes next intruded the caldera fill,helping energize an acid-sulfate hydrothermal system and constitutingthe main surviving record of an early postcaldera andesite-dacite pilepresumed to have been large. Most of the pre- and postcalderarhyodacites were dated by (super 40) Ar/ (super 39) Ar or K-Armethods, and 13 were drilled for remanent magnetic directions. Inagreement with the radiometric ages, the paleomagnetic data indicatethat eruptions took place before, during, and after the JaramilloNormal Polarity Subchron, and that one rhyodacite with transitionalpolarity may represent the termination of the Jaramillo. Most of thebiotite-hornblende-orthopyroxene-plagioclase rhyodacite lavas, dikes,and tuffs are in the range 68-73% SiO (sub 2) , but there were largecompositional fluctuations during the 300-kyr duration of therhyodacite episode. The rhyodacitic magma reservoir was wider (11 km)than the caldera that collapsed into it (8 km)." LA English FE "References: 40; illus. incl. 3 plates, 7 tables, geol. sketch map" PY 2004 PT Serial; Analytic CP Netherlands (NLD) LL "Latitude:N483000,N490000 Longitude:W1203000,W1213000" CL 24 Quaternary geology; 05A Igneous and metamorphic petrology CY "GeoRef, Copyright 2007, American Geological Institute. Referenceincludes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam,Netherlands" UD 200701 DO 10.1016/S0377-0273(03)00290-7 AN 2007-002412 JV 130 JI 4-Mar JP 227-264 Sample Data Item Age Max_age Min_age Age Max_age Min_age Unit Location_Name LatDD LongDD Loc_prec SiO2 TiO2 Al2O3 FeOT MnO MgO CaO Na2O K2O P2O5 LOI Total Rb Sr Y Zr Ba Ce V Zn Rock_Class Rock_Type Sample_Description Collected_by Material State Units Ma Ma Ma Ma Ma Ma DD DD wt % wt % wt % wt % wt % wt % wt % wt % wt % wt % wt % wt % ppm ppm ppm ppm ppm ppm ppm ppm Method 1 1 1 2 2 2 3 3 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 Sample Name 618 0.992 1.006 0.978 rck Camp Kiser 48.81923942 -121.741275 0.001 70.8 0.44 17.26 2.13 0.05 0.67 0.38 5.72 2.04 0.14 2.52 96.65 39 419 19 227 1010 rhyodacite volcanic Slabby lava flow Hildreth and others Whole rock Washington 628 1.015 1.033 0.997 rdd Cougar Divide 48.85508193 -121.8126283 0.001 72.1 0.5 16.31 0.91 0.02 0.2 1.85 4.63 2.98 0.09 2.19 96.8 50 274 21 251 1090 rhyodacite volcanic Lava remnant that intrudes and overlies basement argillite Hildreth and others Whole rock Washington 212 1.012 1.02 1.004 rpd Ptarmigan Dome 48.83322147 -121.7041332 0.001 rhyodacite volcanic "Largest intracaldera dome, multilobate" Hildreth and others Whole rock Washington 145 1.018 1.026 1.01 rcr Chowder Ridge 48.82545326 -121.8350902 0.001 71.6 0.38 15.24 2.02 0.03 0.64 1.8 4.61 3.12 0.12 1.25 98.01 69 245 18 220 990 rhyodacite volcanic Intrusive felsite pod Hildreth and others Whole rock Washington 82-2 1.063 1.075 1.051 ril Iceberg Lake 48.85136114 -121.7172965 0.001 rhyodacite volcanic "small lava remnants, mostly glassy, including proximal fused-breccia facies" Hildreth and others Whole rock Washington 630 1.041 1.052 1.03 rwc Wells Creek 48.8388608 -121.7257926 0.001 73.1 0.38 14.59 2.11 0.04 0.44 1.59 4.18 3.04 0.1 1.59 97.44 57 235 16 212 1060 rhyodacite volcanic Lava flow Hildreth and others Whole rock Washington 287 1.109 1.128 1.09 rcx Corax Dome 48.82065709 -121.7221263 0.001 71.1 0.44 15.58 2.22 0.03 0.43 2.11 4.73 2.81 0.17 1.2 97.8 54 293 17 212 1180 49 27 48 rhyodacite volcanic Intrusive-extrusive dome Hildreth and others Whole rock Washington 227 1.114 1.125 1.103 rod Oreamnos Dome 48.81190987 -121.7291999 0.001 rhyodacite volcanic "Dome with 250 m relief, intrudes and overlies ignimbrite near south-central margin of caldera" Hildreth and others Whole rock Washington 188 1.149 1.159 1.139 ris Swift Creek 48.84105226 -121.6957122 0.001 72.5 0.36 14.41 2.1 0.06 0.81 2.15 3.8 3.34 0.12 4.56 94.7 67 285 16 146 910 <30 35 rhyodacite volcanic Intracaldera rhyodacite ignimbrite Hildreth and others Whole rock Washington 583 1.151 1.167 1.135 rdc Deadhorse Creek 48.8648041 -121.8123603 0.001 71.3 0.36 15.33 2.45 0.06 0.42 2.04 4.37 3.06 0.17 1.68 97.34 67 298 204 rhyodacite volcanic Lava flow Hildreth and others Whole rock Washington 275C 1.18 1.197 1.163 rsr Swift-Rainbow Divide 48.80363415 -121.7130668 0.001 72.2 0.35 15.65 1.18 0.02 0.28 1.86 4.89 3.04 0.12 0.86 98.63 60 266 16 223 1090 50 25 39 rhyodacite volcanic Hildreth and others Whole rock Washington 622 1.215 1.231 1.199 rps South Rim of Caldera 48.80738295 -121.7265904 0.001 71.2 0.43 15.07 2.44 0.06 1.14 2.62 2.95 3.56 0.12 4.14 95.46 87 332 13 140 883 rhyodacite volcanic "Stratified welded tuff Intercalated fall, flow, and surge deposit" Hildreth and others Whole rock Washington 626 1.293 1.309 1.277 rcd Cougar Divide 48.83993183 -121.8266148 0.001 rhyodacite volcanic NNW-trending dikes Hildreth and others Whole rock Washington 380 3.722 3.742 3.702 Tht Hannegan Tuff 48.89983573 -122.8990196 0.001 rhyolite volcanic Rhyolitic ignimbrite and intercalated wall-collapse breccias Hildreth and others Whole rock Washington 636A 0.674 0.837 0.511 gbc Bar Creek 48.81870854 -121.7916531 0.001 62.9 0.86 16.51 5.26 0.1 2.53 5.12 4.1 1.98 0.24 2 97.37 37 509 26 206 844 granodiorite plutonic Small porphyritic granodiorite stock Hildreth and others Whole rock Washington 201 0.969 0.998 0.94 Tgla Lake Ann 48.83504003 -121.7885736 0.001 granodiorite plutonic Non-por phyritic granodioritic to quartz-monzodioritic stock Hildreth and others Whole rock Washington 333 2.75 3.88 2.62 fbc Bar Creek 48.83232828 -121.6414317 0.001 felsite volcanic felsite breccia Hildreth and others Whole rock Washington 493 1.191 1.285 1.097 dbm Barometer Mountain 48.85768144 -121.7348176 0.001 66.3 0.63 16.36 4.03 0.08 1.66 4.18 3.85 2.239 0.27 2.3 96.82 84 465 18 181 1000 43 75 59 dacite volcanic lava remnant Hildreth and others Whole rock Washington 500 1.155 1.285 1.025 adc Chowder Ridge 48.8236957 -121.8392182 0.001 61 0.84 17.42 5.89 0.13 2.54 5.62 4.05 1.86 0.28 2.21 96.73 38 537 20 151 733 30 147 73 andesite volcanic Extracaldera andesite-dacite dikes Hildreth and others Whole rock Washington 316 1.155 1.193 1.117 rsw Swift Creek 48.81673882 -121.6936187 0.001 68.1 2.52 rhyodacite volcanic Hornblende-bearing dike exposed Hildreth and others Whole rock Washington 145 1.06 1.07 1.05 rcr Chowder Ridge 48.82636643 -121.8364315 0.001 71.6 3.445 rhyodacite volcanic Intrusive felsite pod Hildreth and others Whole rock Washington 212 1.032 1.043 1.021 rpd Ptarmigan Dome 48.83035225 -121.7041657 0.001 70.8 0.4 15.4 2.31 0.05 0.65 1.86 4.89 3.1 0.12 1.01 98.31 70 265 18 235 970 43 41 rhyodacite volcanic "Largest intracaldera dome, multilobate" Hildreth and others Whole rock Washington 356 0.674 0.837 0.511 gbc Bar Creek 48.81782343 -121.7930366 0.001 64.6 0.73 16.21 4.53 0.08 2.08 4.42 4.55 2.12 0.23 1.17 97.68 granodiorite plutonic Small porphyritic granodiorite stock Hildreth and others Whole rock Washington 276B 1.005 1.022 0.988 asr Swift-Rainbow divide 48.79892049 -121.709061 0.001 60.5 1.754 andesite volcanic Phenocryst-poor lava remnant Hildreth and others Whole rock Washington 93 0.878 0.896 0.86 atc Thompson Creek 48.85998354 -121.8697377 0.001 55.5 1.556 andesite volcanic Lava-flow remnant Hildreth and others Whole rock Washington 91 0.859 0.873 0.845 alm Lookout Mountain 48.81569783 -121.9429308 0.001 59.8 1.619 andesite volcanic Lava-flow remnant Hildreth and others Whole rock Washington 81 0.743 0.777 0.709 ail Iceberg Lake 48.85303416 -121.7213024 0.001 62.1 1.879 andesite volcanic Hornblende-bearing lava-flow remnant Hildreth and others Whole rock Washington 99 0.515 0.523 0.507 alr Lasiocarpa Ridge 48.83443186 -121.7476677 0.001 61.1 2.436 andesite volcanic Hildreth and others Whole rock Washington 89 0.305 0.311 0.299 acp Coleman Pinnacle 48.81815403 -121.7398996 0.001 59.4 3.308 andesite volcanic Hildreth and others Whole rock Washington 10 0.309 0.322 0.296 atm Table Mountain 48.84736315 -121.6969113 0.001 60.7 1.623 andesite volcanic andesite flow Hildreth and others Whole rock Washington 391 0.301 0.306 0.296 atm Table Mountain 48.85528674 -121.6817094 0.001 62.6 2.707 andesite volcanic andesite flow Hildreth and others Whole rock Washington 572 0.048 0.066 0.03 asw Swift Creek 48.78775739 -121.6766722 0.001 55.6 1.305 andesite volcanic Hildreth and others Whole rock Washington 492 1.191 1.285 1.097 dbm Barometer Mountain 48.8567671 -121.7334773 0.001 65.1 0.6 16.46 4.22 0.09 2.23 4.82 3.94 1.87 0.25 3.51 95.81 61 467 17 167 904 40 79 62 dacite volcanic lava remnant Hildreth and others Whole rock Washington s129 1.293 1.309 1.277 rcd Cougar Divide 48.83886132 -121.8266022 0.001 69.2 0.44 15.74 3.37 0.03 0.9 2.61 4.3 2.85 0.15 1.68 97.44 61 375 16 198 1000 35 55 rhyodacite volcanic NNW-trending dikes Hildreth and others Whole rock Washington s626 1.293 1.309 1.277 rcd Cougar Divide 48.83796192 -121.8266232 0.001 65.4 0.59 16.64 4.25 0.04 1.52 4.3 4.15 2.48 0.2 3.01 96.36 52 607 18 172 969 rhyodacite volcanic NNW-trending dikes Hildreth and others Whole rock Washington n627 1.293 1.309 1.277 rcd Cougar Divide 48.84600085 -121.8209833 0.001 69.8 0.56 15.95 2.81 0.03 0.41 2.29 4.89 2.72 0.15 1.84 97.67 46 314 19 257 957 rhyodacite volcanic NNW-trending dikes Hildreth and others Whole rock Washington 297 1.151 1.167 1.135 rdc Deadhorse Creek 48.86300532 -121.8124029 0.001 71.9 0.35 15.41 1.61 0.02 0.26 2.23 4.65 3.05 0.15 0.73 98.27 65 295 17 203 1260 52 26 32 rhyodacite volcanic Lava flow Hildreth and others Whole rock Washington 621A 1.18 1.197 1.163 rsr Swift-Rainbow Divide 48.80078013 -121.7144605 0.001 70.4 0.37 15.63 2.34 0.07 0.74 2.35 4.7 2.9 0.1 2.66 96.61 55 332 18 225 946 rhyodacite volcanic Hildreth and others Whole rock Washington 96 1.149 1.159 1.139 ris Swift Creek 48.82986076 -121.7409687 0.001 73.3 0.36 13.26 2.25 0.06 1.04 3.21 3.76 2.2 0.14 2.78 95.36 44 295 20 120 900 30 46 rhyodacite volcanic Intracaldera rhyodacite ignimbrite Hildreth and others Whole rock Washington 189 1.149 1.159 1.139 ris Swift Creek 48.84105226 -121.6957122 0.001 60.2 0.9 17.61 6.25 0.11 2.66 6.04 3.78 1.78 0.25 2.56 96.12 33 650 20 116 560 <30 63 rhyodacite volcanic Intracaldera rhyodacite ignimbrite Hildreth and others Whole rock Washington 321 1.149 1.159 1.139 ris Swift Creek 48.83109756 -121.6905201 0.001 71 0.42 15.08 2.6 0.07 1.25 4.15 2.3 2.57 0.16 10.8 88.5 48 325 11 130 869 41 36 40 rhyodacite volcanic Intracaldera rhyodacite ignimbrite Hildreth and others Whole rock Washington 137 0.992 1.006 0.978 rck Camp Kiser 48.8191277 -121.7466868 0.001 72.3 0.45 15.7 2.09 0.06 0.73 0.45 4.02 3.59 0.15 2.1 97.06 64 360 20 210 1500 <30 53 rhyodacite volcanic Slabby lava flow Hildreth and others Whole rock Washington 290 1.109 1.128 1.09 rcx Corax Dome 48.81798918 -121.7249187 0.001 72.6 0.41 14.8 2.27 0.05 0.22 1.99 4.45 2.64 0.17 1.46 97.56 40 297 16 195 1110 49 30 43 rhyodacite volcanic Intrusive-extrusive dome Hildreth and others Whole rock Washington 451 1.109 1.128 1.09 rcx Corax Dome 48.81529107 -121.7249871 0.001 71.2 0.42 14.98 2.71 0.08 1.11 2.75 3.62 2.58 0.15 4.73 94.37 48 268 17 184 1010 50 32 48 rhyodacite volcanic Intrusive-extrusive dome Hildreth and others Whole rock Washington 452 1.109 1.128 1.09 rcx Corax Dome 48.81526089 -121.7222635 0.001 70.4 0.43 15.61 2.57 0.06 0.9 2.47 4.31 2.74 0.16 2.24 96.73 53 287 18 201 1120 rhyodacite volcanic Intrusive-extrusive dome Hildreth and others Whole rock Washington 80 1.063 1.075 1.051 ril Iceberg Lake 48.8512203 -121.7199854 0.001 71.3 0.37 15.11 2.24 0.06 0.58 1.69 4.46 3.67 0.14 3.88 95.28 68 200 239 rhyodacite volcanic "small lava remnants, mostly glassy, including proximal fused-breccia facies" Hildreth and others Whole rock Washington 82 1.063 1.075 1.051 ril Iceberg Lake 48.84940643 -121.7186685 0.001 72.3 0.34 14.66 1.9 0.06 0.48 1.5 4.96 3.33 0.09 3.93 95.1 68 190 20 245 1050 <30 40 rhyodacite volcanic "small lava remnants, mostly glassy, including proximal fused-breccia facies" Hildreth and others Whole rock Washington 448B 1.063 1.075 1.051 ril Iceberg Lake 48.84939127 -121.7173057 0.001 73 0.33 14.7 1.86 0.02 0.14 1.34 4.89 3.26 0.09 0.9 97.97 64 173 18 239 1140 47 22 45 rhyodacite volcanic "small lava remnants, mostly glassy, including proximal fused-breccia facies" Hildreth and others Whole rock Washington 631 1.063 1.075 1.051 ril Iceberg Lake 48.84939127 -121.7173057 0.001 73.3 0.34 14.76 1.37 0.03 0.16 1.34 4.86 3.36 0.1 0.46 98.61 62 170 17 237 1100 rhyodacite volcanic "small lava remnants, mostly glassy, including proximal fused-breccia facies" Hildreth and others Whole rock Washington 228 1.127 1.138 1.116 rod Oreamnos Dome 48.81082435 -121.7278246 0.001 69 0.55 16.19 1.75 0.04 1.07 3.48 4.51 2.71 0.29 1.19 97.83 54 660 16 198 1000 53 36 rhyodacite volcanic "Dome with 250 m relief, intrudes and overlies ignimbrite near south-central margin of caldera" Hildreth and others Whole rock Washington 378 1.127 1.138 1.116 rod Oreamnos Dome 48.81001492 -121.7360174 0.001 70.8 0.55 15.05 4.15 0.08 1.34 1.25 3.82 2.3 0.23 3.6 95.44 33 289 182 rhyodacite volcanic "Dome with 250 m relief, intrudes and overlies ignimbrite near south-central margin of caldera" Hildreth and others Whole rock Washington 455 1.127 1.138 1.116 rod Oreamnos Dome 48.81442182 -121.7277335 0.001 64.8 0.57 17.2 3.85 0.08 1.31 4.21 4.56 2.78 0.27 3.78 95.12 52 644 183 rhyodacite volcanic "Dome with 250 m relief, intrudes and overlies ignimbrite near south-central margin of caldera" Hildreth and others Whole rock Washington 73 1.013 1.021 1.005 rpd Ptarmigan Dome 48.83754711 -121.7039801 0.001 71.2 0.4 15.1 2.29 0.04 0.6 1.81 4.82 3.16 0.13 0.96 98.28 67 255 29 235 970 58 40 rhyodacite volcanic "Largest intracaldera dome, multilobate" Hildreth and others Whole rock Washington 190 1.013 1.021 1.005 rpd Ptarmigan Dome 48.83833877 -121.6944198 0.001 71.1 0.37 15.15 2.17 0.05 0.59 1.84 4.97 3.28 0.1 0.63 98.64 79 240 22 240 950 30 46 rhyodacite volcanic "Largest intracaldera dome, multilobate" Hildreth and others Whole rock Washington 291 1.013 1.021 1.005 rpd Ptarmigan Dome 48.82783689 -121.7205812 0.001 71.2 0.4 15.22 2.23 0.04 0.52 1.78 4.92 3.1 0.15 1.04 98.14 67 236 16 227 1030 49 27 50 rhyodacite volcanic "Largest intracaldera dome, multilobate" Hildreth and others Whole rock Washington n315 1.155 1.193 1.117 rsw Swift Creek 48.82560825 -121.6824882 0.001 67.3 0.63 15.72 3.7 0.08 1.34 3.21 4.83 2.63 0.21 0.94 98.18 49 356 22 241 997 44 57 57 rhyodacite volcanic Hornblende-bearing dike exposed Hildreth and others Whole rock Washington s316 1.155 1.193 1.117 rsw Swift Creek 48.81673882 -121.6936187 0.001 68.1 0.57 15.36 3.35 0.07 1.45 2.9 4.89 2.68 0.19 1.34 97.94 50 286 20 198 911 40 58 52 rhyodacite volcanic Hornblende-bearing dike exposed Hildreth and others Whole rock Washington 299 1.015 1.033 0.997 rdd Cougar Divide 48.85402545 -121.8139786 0.001 70.2 0.49 15.59 2.56 0.04 0.65 2.04 4.89 2.96 0.16 1.59 97.73 56 263 21 244 1150 54 35 59 rhyodacite volcanic Lava remnant that intrudes and overlies basement argillite Hildreth and others Whole rock Washington 356A 0.674 0.837 0.511 gbc Bar Creek 48.81782343 -121.7930366 0.001 68.9 0.52 15.64 2.94 0.08 1.04 2.64 4.75 2.92 0.2 2.29 94.87 47 326 20 217 1130 38 40 20 granodiorite plutonic Small porphyritic granodiorite stock Hildreth and others Whole rock Washington 636B 0.674 0.837 0.511 gbc Bar Creek 48.81870854 -121.7916531 0.001 65.4 0.78 16.14 4.29 0.08 1.74 4.28 4.17 2.47 0.2 2.57 95.47 39 460 26 255 932 granodiorite plutonic Small porphyritic granodiorite stock Hildreth and others Whole rock Washington 636C 0.674 0.837 0.511 gbc Bar Creek 48.81870854 -121.7916531 0.001 59.8 0.84 18.11 5.72 0.11 3.16 6.26 3.83 1.49 0.22 2.49 96.1 28 712 19 118 658 granodiorite plutonic Small porphyritic granodiorite stock Hildreth and others Whole rock Washington Method Data 1 AR-AR:PLAG 56 2 AR-AR:BIO 56 3 TABLE 2007-002412 4 XRF 347