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