Geologic Map of the Grand View-Bruneau Area, Owyhee County, Idaho Margaret D. Jenks Bill Bonnichsen Martha M. Godchaux Idaho Geological Survey Technical Report 98- 1 University of Idaho December 1998 Moscow, Idaho 83844-3014 Contents Introduction ............................................................... 1 Location ................................................................ 2 General Geologic Setting ........................................................ 2 Structure ................................................................ 5 Hotsprings ............................................................... 6 Acknowledgments ........................................................... 7 References ............................................................... 7 DescriptionofUnits .......................................................... 9 SedimentqUnits .......................................................... 9 Younger Unconsolidated Sediments ............................................... 9 Qal Alluvium (Holocene) .................................................. 9 Qil Intermittent lake sediments (Holocene) ......................................... 9 Qfs Fresh, unvegetated dune sand (Holocene) ....................................... 9 Qaf Alluvial fan deposits (Holocene and Pleistocene) ........................ :.............. 9 Qds Vegetated dune sand (Holocene and Pleistocene) ................................... 9 Qls Landslide deposits (Holocene and Pleistocene) .................................... 9 Qbf Bonneville Flood deposits (Pleistocene) ....................................... 9 Gravel Surfaces and Lenses ................................................... 10 QTg Gravel surface, lithology undivided (Quaternary or Tertiary) ............................. 10 QTgq Gravel surface, abundant quartzite (Quaternary or Tertiary) ............................. 10 QTgqb Gravel surface, abundant quartzite, signiticant basalt (Quaternary or Tertiary) ................... 10 QTgr Gravel surface, abundant rhyolite (Quaternaty or Tertiary) ............................. 10 QTgrb Gravel surface, abundant rhyolite, significant basalt (Quaternary or Tertiary) .................... 10 QTge Gravel surface, abundant Eocene volcanics (Quaternary or Tertiary) ........................ 11 Tgq Gravel lens or surface, abundant quartzite (Tertiary) ................................. 11 Tgqb Gravel lens, abundant quartzite, significant basalt (Tertiary) ............................. 11 Tgr Gravel lens or surface, abundant rhyolite (Tertiary) .................................. 11 Tge Gravel lens or surface, abundant Eocene volcanics (Tertiary) ............................. 11 Tgeb Gravel lens or surface, abundant Eocene volcanics, significant basalt (Tertiary) ................... 11 IdahoGroupSediiments ..................................................... 11 Ti Clay- to sand-sized sediments (Miocene to Pliocene) ................................ 12 Tsi Silicic tuff (Miocene to Pliocene) .......................................... 12 Tf Sand- to gravel-sized sediments, fermginous and phosphatic cemented or stained (Miocene to Pliocene) ..... 13 Tbs Basaltic tuff (Miocene to Pliocene) ......................................... 13 Tls Limestone, undifferentiated (Miocene to Pliocene) ................................. 13 Thot Reefal limestone of Hot Spring (Miocene to Pliocene) ........................., .... 13 Tsoo Oolite of Shoofly Creek (Miocene to Pliocene) .................................... 13 VolcanicUnits ........................................................... 13 Basalt Volcanoes and Lava Flows ............................................... 13 NorthAreaUnits ....................................................... 14 Qe Basalt of Rattlesnake Springs (Pleistocene) ..................................... 14 Qstr Basalt of Strike Dam Road (Pleistocene) ...................................... 14 QTsirn Basalt of Simco Road (Pliocene or Pleistocene) ................................. 15 QTcrf Basalt of Crane Falls (Pliocene or Pleistocene) .................................. 15 Tcg Basalt of Chalk Gulch (Pliocene) .......................................... 15 Tfly Basalt of Flying H Ranch (Pliocene) ........................................ 15 Tcan Basalt of Canyon Creek (Pliocene) ......................................... 15 Tgsm Basalt of Goldsmith Road (Pliocene) ....................................... 15 Tkl Basalt of Katie Lane (Pliocene) ........................................... 15 Tdix Basalt of Dixie Road (Pliocene) .......................................... 15 SouthAreaUnits ......................................................... 16 Twc Basalt of Winter Camp Butte (Pliocene) .......................................16 Tphb Tuff of the Pot Hole Butte volcanic complex (Pliocene) ..............................16 Tbrc Basalt of Browns Creek (Pliocene) ..........................................16 Tpeb Basalt of Pence Butte (Pliocene) ...........................................16 Tlbbu Upper basalt of Lower Black Butte Crossing (Pliocene?) .............................16 Tlbbl Lower basalt of Lower Black Butte Crossing (Pliocene?) .............................16 Twfb Pillow basalt of West Fork Browns Creek (Pliocene) ................................16 Tsog Basalt of Seventy One Gulch (Pliocene) .......................................16 Tcuf Basalt of Curlew Flat (Pliocene) ...........................................16 Thc Basalt of Hot Creek (Pliocene) ............................................ 17 Tid Basalt of Indian Bathtub (Pliocene) ......................................... 17 Tbuc Basalt of Buckaroo Dam (Pliocene) ......................................... 17 Tharu Upper basalt of Harris Dam (Pliocene) .......................................17 Tharl Lower basalt of Hams Dam (Pliocene) ........................................17 Tcro Basalt of Crowbar Gulch (Pliocene) ......................................... 17 ...... Tbm Upper basalt of Bruneau River (Pliocene) .......................................17 Tbrm Middle basalt of Bruneau River (Pliocene) .....................................17 Tbrl Lower basalt of Bruneau River (Pliocene) ...................................... 17 Tbr Basalt of Bruneau River (Pliocene) .......................................... 18 Tmw Basalt of Miller Water (Pliocene) ..........................................18 Troc Basalt of Rock Lake (Pliocene) ............................................ 18 Tbib Basalt of Big Bend (Pliocene) ............................................ 18 Ttwi Basalt of Twin Butte (Pliocene) ........................................... 18 Tsal Basalt of Salvador Lake (Pliocene) .......................................... 18 Tab Basalt of Austin Butte (Pliocene) ...........................................18 Ttab Basalt of Table Butte (Pliocene) ........................................... 18 Tbwf Basalt of Broken Wagon Flat (Pliocene) ...................................... 18 Tbgr Basalt of Blackstone Grasmere Road (Pliocene) ...................................19 Tsot Basalt of South Top (Pliocene) ............................................ 19 Thtc Basalt of Horse Trap Corral (Pliocene) ........................................19 Tsug Basalt of Sugar Creek (Pliocene) ...........................................19 Tww Basalt of Windy Well (Pliocene) ........................................... 19 Tmbr Basalt of Missile Base Road (Pliocene) ........................................19 Tbla Basalt of Black Rocks (Pliocene) ...........................................19 Tdea Basalt of Deadman Gulch (Pliocene) ........................................19 Tals Basalt of Al Sadie Ranch (Pliocene) .........................................19 Thir Basalt of Hole In Rock (Pliocene) ..........................................19 Twhc Basalt of Wickahoney Creek (Pliocene) ........................................20 Twt Basalt of Whiclcney Tree Reservoir (Pliocene) ..........................: .........20 To1 Basalt of 0 X Lake (Pliocene) .............................................20 Rhyolite Lava Flows .......................................................20 TN Rhyolite, lmdifferentiated (Miocene) ..........................................20 Thb Rhyolite of Horse Basin (Miocene) ...........................................20 Tsfc Rhyolite of Shoofly Creek (Miocene) .........................................20 Tsc Rhyolite of Sheep Creek (Miocene) ...........................................20 Tpc Rhyolite of Perjue Canyon (Miocene) ..........................................21 Thg Rhyolite of Halfway Gulch (Miocene) .........................................21 Tbtc Rhyolite of Behveen The Creeks (Miocene) ......................................21 Tts Rhyolite of Tigert Spring (Miocene) ...........................................21 Top Rhyolite of 0 X Prong (Miocene) ...........................................21 Trc Rhyolite of Rattlesnake Creek (Miocene) ........................................21 Older Volcanic Units .......................................................21 Tev Eocene volcanics .................................................. .21 Figure Figure 1. Location map of the study area. ............................................... 2 Plates The following 7.5-minute quadrangles in this report are purchased separately:.... Pence Butte, Pot Hole Butte, Bruneau Dunes,Hot Spring, Crowbar Gulch, Austin Butte, Bruneau, Sugar Valley, Broken Wagon Flat, Table Butte, C.J. Strike Dam, Little Valley, Hole