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Amoco Prod. Co.#19-1 Milford Federal

Amoco Prod. Co.#1 Idaho State

4057

52

60

62

42

22

4050

2516

20

4632

65

70

65

35

34

60

45

5385

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28

58

5215

25

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20

40

932

7

37

C A R M E NS T O C K

BIG E

IGHTM

ILE STOCK

P O I S O N

C R E E K

F A U L T

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44°30'44°30'

45°00' 45°00'

45°30' 45°30'

114°00'

114°00'

113°00'

113°00'

113°30'

113°30'

Base from U.S. Geological Survey, Borah Peak, 1989, Leadore, 1980, Salmon, 1981.

Projection: Universal Transverse Mercator, zone 12.

1927 North American Datum

See "Index to sources of geologic mapping"

Editing and digital cartography by Alessandro J. Donatich,

Central Publications Group

Manuscript approved for publication July 1, 2002

U.S. DEPARTMENT OF THE INTERIORU.S. GEOLOGICAL SURVEY

GEOLOGIC INVESTIGATIONS SERIESI–2765 (Sheet 2 of 2)Pamphlet accompanies map

Printed on recycled paper

Any use of trade names in this publication is fordescriptive purposes only and does not imply endorsement by the U.S. Geological Survey

For sale by U.S. Geological Survey Information ServicesBox 25286, Federal Center, Denver, CO 802251-888-ASK-USGS

ArcInfo coverages and a PDF for this map are available at http://pubs.usgs.gov/imap/2003/i-2765/

1 10 KILOMETERS0 1 2 43 5 6 7 8 9

SCALE 1:100 000

CONTOUR INTERVAL 50 METERS (BORAH PEAK, SALMON), 40 METERS (LEADORE)

1 8 MILES10 2 3 4 5 6 7

GEOLOGIC MAP OF THE SALMON NATIONAL FORESTAND VICINITY, EAST-CENTRAL IDAHO

Compiled byKarl V. Evans and Gregory N. Green

2003

Geologic Map of the Eastern Part of the Salmon National ForestBy

K.I. Lund, K.V. Evans, R.G. Tysdal, and G.R. Winkler

DESCRIPTION OF MAP UNITS

[Boxes colored only for units shown on this sheet]

SURFICIAL DEPOSITS

Alluvial, colluvial, landslide, and glacial deposits, undivided (Quaternary)

CENOZOIC SEDIMENTARY ROCKS

Gravel, limestone, sandstone, and volcaniclastic sediments (Holocene to Oligocene(?))

Tuff and tuffaceous conglomerate (Pliocene to Miocene)

Sedimentary rocks—basin fill (Miocene(?) to Eocene)

Older colluvium of Panther Creek (Eocene)

CENOZOIC VOLCANIC ROCKS

Challis Volcanic Group (Eocene)

Challis Volcanic Group, undivided

Tuffs and lavas of Thunder Mountain cauldron complex (southwestern part of Salmon National Forest)—See Fisher and others (1992)

Sunnyside tuff

Perlitic rhyolite

Lapilli tuff

Lower latite lava

Tuffs of Castle Rock segment of Van Horn Peak cauldron complex (southwestern part of Salmon National Forest)—See Ekren (1988)

Tuffs of Castle Rock

Tuffs of Camas Creek–Black Mountain and related rocks of Van Horn Peak cauldron complex (southwestern part of Salmon National Forest)—See Ekren (1988)

Tuffs of Camas Creek–Black Mountain

Intermediate and mafic lavas

Tuff of Eightmile Creek

Tuff of Ellis Creek

TERTIARY TO CRETACEOUS INTRUSIVE ROCKS

Mafic to felsic intrusions, undivided (Eocene)

Gray porphyry (Eocene)

Granite (Eocene)

Granite, granodiorite, and quartz monzodiorite (Eocene)

Intrusive rhyolite (Eocene)

Intrusions, mostly intermediate and felsic (Tertiary to Cretaceous)

Hornblende-biotite tonalite (Cretaceous)

Biotite-muscovite granite (Cretaceous)

Porphyritic granite and granodiorite (Cretaceous)

Biotite granodiorite (Cretaceous)

Foliated biotite granodiorite (Cretaceous)

MESOZOIC TO PROTEROZOIC SEDIMENTARY ROCKS

Dinwoody Formation (Lower Triassic)

Phosphoria Formation (Lower Permian)

Snaky Canyon (Lower Permian to Upper Mississippian) and Bluebird Mountain (Upper Mississippian) Formations, undivided

Surrett Canyon(?), South Creek(?), and Scott Peak Formations (Upper Mississippian) and Middle Canyon (Upper and Lower Mississippian) Formation, undivided

Surrett Canyon, South Creek, and Scott Peak Formations (Upper Mississippian) and Middle Canyon (Upper and Lower Mississippian) Formation, undivided

Railroad Canyon Formation (Upper Mississippian)

Scott Peak Formation (Upper Mississippian)

Middle Canyon Formation (Upper and Lower Mississippian)

McGowan Creek Formation (Lower Mississippian)

Three Forks and Jefferson Formations, undivided (Upper Devonian)

Laketown Dolomite (Silurian) and Saturday Mountain Formation (Lower Silurian to Middle Ordovician), undivided

Saturday Mountain Formation (Lower Silurian to Middle Ordovician)

Kinnikinic Quartzite (Middle Ordovician)

Summerhouse Formation (Lower Ordovician)

Kinnikinic Quartzite (Middle Ordovician) and Summerhouse Formation (Lower Ordovician), undivided

Wilbert Formation (Lower Cambrian to Neoproterozoic?)

PALEOZOIC TO PROTEROZOIC VOLCANIC ROCKS

Metavolcanic and metasedimentary strata (lower Paleozoic(?) to Neoproterozoic)

PALEOZOIC INTRUSIVE ROCKS

Mafic to predominantly felsic alkalic intrusions (Ordovician to Cambrian)

PALEOZOIC TO PROTEROZOIC METAMORPHIC ROCKS

Gray marble (lower Paleozoic(?) to Neoproterozoic)

PROTEROZOIC SEDIMENTARY ROCKS

Lawson Creek Formation (Mesoproterozoic)

Swauger Formation (Mesoproterozoic)

Gunsight Formation (Mesoproterozoic)

Apple Creek Formation, undivided (Mesoproterozoic)

Banded siltite unit

Coarse siltite unit

Diamictite unit

Fine siltite unit

Big Creek Formation (Mesoproterozoic)

Lawson Creek Formation, Swauger Formation, and (or) Lemhi Group, undivided (Mesoproterozoic)

Argillaceous quartzite, unnamed (Mesoproterozoic)

Hoodoo Quartzite (Mesoproterozoic)

Yellowjacket Formation (Mesoproterozoic)

Feldspathic metasandstone (Mesoproterozoic)

Missoula Group, undivided (Mesoproterozoic)

Helena and Empire Formations, undivided (Mesoproterozoic)

Spokane and Greyson Formations, undivided (Mesoproterozoic)

PROTEROZOIC INTRUSIVE ROCKS

Mafic intrusive rock (Neoproterozoic?)

Megacrystic granite and augen gneiss (Mesoproterozoic)

Amphibolite and magnetite-hornblende gneiss (Mesoproterozoic)

PROTEROZOIC METAMORPHIC ROCKS

Biotite gneiss (Mesoproterozoic)

Quartzite (Mesoproterozoic)

Calc-silicate quartzite (Mesoproterozoic)

Basement gneiss (Paleoproterozoic)

Contact—Dashed where approximately located; queried where uncertain. Scratch boundaries used where contacts omitted along lats 44°30' N. and 45° N.

Strike-slip fault—Dashed where approximately located; dotted where concealed. Opposed arrows show relative movement

Normal fault—Dashed where approximately located; dotted where concealed; queried where uncertain. Bar and ball on downthrown side

Thrust fault—Dashed where approximately located; dotted where concealed; queried where uncertain. Sawteeth on upper plate

Low-angle normal fault—Dashed where approximately located; dotted where concealed. Box on upper plate

Thrust fault with later normal movement—Dashed where approximately located; dotted where concealed. Sawteeth on upper plate; bar and ball on downthrown side

Thrust fault with younger-on-older relationship and multiple-stage development—Dashed where approximately located; dotted where concealed. Sawteeth on upper plate. Younger-on-older relationship may be caused by multiple phases of compressional deformation and (or) by decoupling in lower plate during thrust juxtaposition. Superposed brittle deformation by low-angle normal movement

Anticline—Dotted where concealed

Syncline

Overturned anticline—Dotted where concealed

Overturned syncline—Dotted where concealed

Caldera margin

Dikes of unknown age or chemistry

Strike and dip of bedding

Inclined

Overturned

Strike and dip of silicified breccia-zone and cataclasite surface east of Baker and Lemhi, and west of Tendoy, Idaho

Strike and dip of inclined foliation

Bearing and plunge of lineation—May be combined with foliation symbol

Drill hole

Area in which stratigraphic unit occurs at a higher-than-typical metamorphic grade

Brittlely deformed and silicified breccia and cataclasite—Formed along low-angle normal faults during Tertiary regional extension (Tucker, 1983; Janecke and others, 1999). Locally preserved as an erosional remnant forming dip slopes on several ridge spurs on west side of northern Beaverhead Mountains, on top of Ramsay Mountain, and near McDevitt Creek in Lemhi Range. Along Kenney Creek a highly polished, reddish, hematitic, silicified surface of ultracataclasite dips 8° NW. and truncates east-dipping hanging wall of Eocene to Miocene(?) sedimentary strata that intersect the surface at an angle of 60°. Below surface, brecciation is intense but gradually decreases to unbrecciated Proterozoic strata through a 50-m-thick transition zone. The same fault(s) that formed the cataclasite in Beaverhead Mountains has probably been intersected at depth in exploration drill holes at the Humbug gold prospect along Ditch Creek northwest of outpost of North Fork

85

50

12

40

20

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SURFICIALDEPOSITS

SEDIMENTARY ROCKS VOLCANIC ROCKS INTRUSIVE ROCKS METAMORPHIC ROCKS

CORRELATION OF MAP UNITS

Holoceneand

Pleistocene

LowerTriassic

LowerPermian

UpperMississippian

LowerMississippian

LowerSilurian

UpperOrdovician

MiddleOrdovician

LowerOrdovician

Lower Cambrian

UpperDevonian

Pliocene

Miocene

Oligocene

Eocene

QUATERNARY

TERTIARY

CRETACEOUS

TRIASSIC

PERMIAN

PENNSYLVANIAN

MISSISSIPPIAN

DEVONIAN

SILURIAN

ORDOVICIAN

CAMBRIAN

NEOPROTEROZOIC

MESOPROTEROZOIC

PALEOPROTEROZOIC

?

?

?

?

?

Thunder Mountaincauldron complex

CastleRock

Camas Creek–Black Mountain

Unconformity

Unconformity

Unconformity

Unconformity

Unconformity

Unconformity

Unconformity

Unconformity

Unconformity

Unconformity Unconformity

Rel

ativ

e ag

eun

know

n

Rel

ativ

e ag

eun

know

n

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know

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xim

ate

Lemhi Group

?

?

114°30' 114°00' 113°30'

45°30'

45°00'

44°30'

Anderson (1959)

Anderson (1961)

Bennett (1977)

Cater and others (1973)

Connor (1990)

Connor and Evans (1986)

Desmarais (1983)

Ekren (1988)

Evans (1981)

Evans and Connor (1993)

Hait (1965)

Hillesland (1981)

Kaiser (1956)

Lopez (1982a)

Lopez (1982b)

Lucchitta (1966)

Lund, Evans, and Esparza (1983)

Lund, Rehn, and Holloway (1983)

Lund and others (1992)

Maley (1974)

M’Gonigle (1994)

Rember and Bennett (1979)

Ruppel (1968)

Ruppel (1980)

Ruppel and Lopez (1981)

Ruppel and others (1993)

Schmidt and others (1994)

Shockey (1957)

Skipp and others (1984)

Spence (1984)

Staatz (1973)

Staatz (1979)

Tucker (1975)

Tysdal (1996a)

Tysdal (1996b)

Tysdal (1996c)

Tysdal (2000b, 2003)

Tysdal (2002)

Tysdal and Desborough (1997)

Tysdal and others (2000)

Tysdal and Moye (1996)

Unpublished mapping, K.V. Evans, USGS, 1995–97

Unpublished mapping, K.V. Evans, USGS, 1993–97

Unpublished mapping, K.V. Evans, F. Moye, and R.F. Hardyman, USGS, 1991–94

Unpublished mapping, K.I. Lund, USGS, 1995–2000

Unpublished mapping, G.R. Winkler, USGS, 1995–97, and R.G. Tysdal, USGS, 1999–2001

Unpublished mapping, G.R. Winkler, USGS, 1994–96

Unpublished mapping, K.I. Lund, USGS, 1997

Unpublished mapping, R.G. Tysdal, USGS, 1997–99

Unpublished mapping, R.G. Tysdal and K. Lund, USGS, 1997–99

Unpublished mapping, R.G. Tysdal, USGS, 1996–98

Unpublished mapping, R.G. Tysdal, USGS, 1998–2000

Unpublished mapping, K.I. Lund, USGS, 2000–01

SOURCES OF GEOLOGIC MAPPING

INDEX TO SOURCES OF GEOLOGIC MAPPING

Salmon National Forest

EXPLANATION

1

2

3

4

5

6

7

8

9

10

11

12

30

31

32

33

34

35

36

40

41

42

43

44

45

46

47

28

48

38

49

50

51

39

37

52

53

13

14

15

16

17

18

19

21

20

22

23

24

25

26

27

29

19

4 27

18

173

12

1330

1542

114

7

2622

43

10

40

8

5

39

9 33

46

4144

3447

37

51

52

32

452

38

5049

24 2325

11, 48

35

36

31 21

16

29

6, 28

53

20