North Idaho Batholith Idaho Geologic Provinces Accreted Terrane No Basin and Range rth Belt Supergroup n er Challis Volcanics Th Columbia River Plateau Idaho Batholith s ru Belt Supergroup tB Owyhee Plateau el t Snake River Plain Thrust Belt Columbia River Plateau Be lt Challis Volcanics rst Columbia River Plateau 100 u Th Accreted Terrane Idaho Batholith Miles ³ East-Central Basin & Range Th ur Be lt Owyhee Plateau st Snake River Plain South-East Basin and Range Geology Description TheIdahoBatholithisacompositemassofgraniticplutons coveringapproximately35,000km2.Intrusiveigneousrocks: IdahoBatholith granitic,granodioriteandtonalite.Threelobesseparatedby geologyandgeography;KaniksuLobeintheIdahopanhandle, AtlantaandBitterrootlobesincentralIdaho. Age Period 110‐75Ma LateCretaceous 1470‐1400 Ma Mesoproterozoic Belt Supergroup Mesoproterozoicsedimentaryrocksdepositedinariftbasin locatedinwhatisnownorthIdahoandwesternMontana. MissoulaGroup,PieganGroup,RavalliGroup,andLowerBelt. Northern ThrustBelt North‐westtosouth‐easttrendingthrustfaults(lateCretaceous) 1450‐1400 whichcutthroughMesoproterozoicSedimentaryrocksoftheBelt Madeposits. Supergroup(sandstone,shale,limestone). Idaho‐ Wyoming ThrustBelt TheIdaho‐WyomingthrustbeltisonesegmentoftheCordilleran thrustbeltthatcontainsfoldedandthrustedPaleozoicand Mesozoicsedimentaryrocks.Thethrustfaultsfoldedand compressedearlieremplacedsedimentsinlateMesozoicand earlyTertiary,trendingnorth‐westtosouth‐east. 700‐150Ma deposited. Neoproterozoic, 150to55Ma Paleozoic,Triassic, thrust Jurassic faulting. Challis Volcanics Flare‐upofvolcanicactivityincentralIdahocreatingintrusive pinkgraniteanderuptionsofrhyolitelavas.Andesiteanddacite withextensionalfaulting.Formationofmajormineraldeposits. 52‐45Ma Eocene Accreted Terranes WesternedgecentralIdaho.MiddleCretaceous(120‐100Ma) accretionof"exotic"TerranesofPaleozoiclimestoneontopof oceanicvolcanicrockwithJurassicintrusions.SevenDevils Group. ~370‐250 Ma&150‐ 170Ma intrusions Paleozoic& Mesozoic 17Ma MiddleMiocene ColumbiaRiver Extensiveplateauofvolcanicbasaltandrhyolitelocatedonthe Basalt westernedgeofcentralIdaho. Mesoproterozoic, LateCretaceous Basinand Range Beginningabout17millionyearsago,linearmountainrangesin Neoproterozoic& south‐eastIdaho,consistingofsedimentarysandstone,shaleand 700‐150Ma. Paleozoic limestone,brokenbyNW‐SEtrendingnormalfaults(extensional sediments forces).CutbySnakeRiverPlain SnakeRiver Plain BeltacrosssouthernIdahoconsistingofIdavadaVolcanics, YellowstoneVolcanics(rhyolite),SnakeRiverBasaltwithsome QuaternarySedimentaryrocks.Createdbythepassageofthe continentovera"HotSpot". Owyhee Plateau AregioninsouthwesternIdahorelatedtotheSnakeRiverPlain butremainedahighlandregionofIdavadaandYellowstone 17Ma volcanics,andSnakeRiverBasalt.Felsicvolcanics,Miocenesilicic flowsandtuffs. 17Ma‐ Present Mioceneto Holocene Miocene
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