15

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37

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50

40

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30

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20 39 16

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62

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65

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26

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25

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65

5

4 2

5

7

5

6

5

13

14

65

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66

74

41

88 80

40

30

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60

48

60

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10

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55

87 70

55

75

80

75 80

85

75

80 75 85 67

60

35 90 80

74

66

76

58

65

64

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56

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35

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56

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48 80 65

60

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42

80

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77

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72

83

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64 47

65

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70 30

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23

25

55

65

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65

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45

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15

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30

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34

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15

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72 30 30

20 20 29

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82

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60

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55

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60 60 55

61

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52

27

36

10

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18

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34

52

32

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80

85

87

68 82

88 90

78

75

85

60

84

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55

30

35

40

60

70

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50

75

85

75

65

85 80

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15

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50 80

50

30

36

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25

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32

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22

22

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48

40

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15

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13

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41

30

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25

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15

15

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9 10

20

4

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15

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Qa3

Qa3

Qa3

Qa4

Qa2

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Qa2

Qa2

Qa4

Qa4

Qa4

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Qcm

Qa2

Qa4

Qa4

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Xag

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Xag

Qa4

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Tsb

Tsb

Qa4

Qa2

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Qa2

Qa4

Qa4

Qa4

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Qa2

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Kcg

Qa3

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Qa2

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Qa3

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Qa2

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Qa4

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Qa3

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Qa2

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Qa3

Qa3

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27'30” R. 21 W. R. 201⁄2 W. 25' R. 201⁄2 W. R. 20 W.

T. 16 N.

T. 7 N.

42'30” 42'30”

40'

T. 16 N.

T. 15 N.

40’

27'30” R. 24 W. R. 201⁄2 W. 25'

114°30' 114°22'30”

34°37'30”

34°45'

34°37'30”

34°45’

114°30' 114°22'30”

Figure 2. Map showing Topock quadrangle geology and major structures draped over

hillshade derived from 30-meter digital elevation model. Devil’s Elbow Fault (DEF).

POWELL PEAK FAULT

PULPIT

ROCK FAULT

GOLD DOME

FAULT ZONE

TUMARION PEAK FAULT

DETACHMENT FAULT

MOHAVE WASH FAULT

MOHAVE WASH FAULT

MOHAVE WASH FAULT

CHEMEHUEVI

CHEMEHUEVI

DEF

DEF

DEF

DETACHMENT

POWELL PEAK

PLUTON

BORROW PIT

BODY

NEEDLE MTN

INTRUSION

Any use of trade, product, or firm names in this publication is for descriptive purposes only and 

does not imply endorsement by the U.S. Government

For sale by U.S. Geological Survey, Information Services, Box 25286, Federal Center, Denver, CO 

80225, 1–888–ASK–USGS

Digital files available at http://pubs.usgs.gov/sim/3236/

Suggested citation: Howard, K.A., John, B.E., Nielson, J.E., Miller, J.M.G., and Wooden, J.L., 

2013, Geologic map of the Topock 7.5’ quadrangle, Arizona and California: U.S. Geological 

Survey Scientific Investigations Map 3236, pamphlet 60 p., scale 1:24,000 

[http://pubs.usgs.gov/sim/3236/].

114°30' 27'30” R. 24 W. R. 201⁄2 W. 25' 114°22'30”

34°37'30”

40’

34°45'

T. 16 N.

T. 7 N.

42'30”

34°37'30”

40'

42'30”

34°45’

114°30' 27'30” 25' 114°22'30”

T. 16 N.

T. 15 N.

R. 21 W. R. 201⁄2 W. R. 201⁄2 W. R. 20 W.

1

 U.S. Geologcial Survey

2

 Department of Geology and Geophysics, University of Wyoming

3

 Department of Geology, Vanderbilt University

4

 Environmental Sciences, Stanford University

Geologic Map of the Topock 7.5’ Quadrangle, Arizona and California

By

Keith A. Howard1

, Barbara E. John1, 2, Jane E. Nielson1, Julia M.G. Miller3, and Joseph L. Wooden4

2013

METERS

400

-400

-600

-800

200

-200

sea level

B

B'

FEET

1,000

-1,000

-2,000

-3,000

sea level

Tmgn

Tcgn

Tmg

Xgm

Xg Yd

Kcg

Xgm Mohave Wash plate DEVILS ELBOW FAULT

Qa4

Qa4 Tsb Tsb

Tp

Ts

Tv

Xg

Xg

Xg

Kcb

Tdm

KYq

Qa4 Qa4 Tv

TKl Kcb

TKq Xg Tdl

Xag

Xag

TKq

Qa2

Qa4

Yd

Yd ?

QTcg

water

Tmgn

Footwall of Chemehuevi Core Complex

CHEMEHUEVI DETACHMENT FAULT

MOHAVE WASH FAULT

GOLD DOME

FAULT ZONE

TUMARION PEAK FAULT

POWELL PEAK PLUTON

POWELL PEAK FAULT

Section A–A' TUMARION BLOCK

Tmgn Tmgn

B ́

B

faulted Miocene and

Proterozoic rocks

Kcg

feeder

dike?

faulted Xg and Yg

CHEMEHUEVI DETACHMENT FAULT

Well 14bca

(Metzger and

Loeltz, 1973)

JACKPOT BLOCK

TUMARION BLOCK

Borrow pit GOLD DOME FAULT ZONE

body Sacramento Wash 

METERS

400

-400

-600

-800

200

-200

sea level

Qa4

Section B–B'

A A'

FEET

1,000

-1,000

-2,000

-3,000

sea level

Trbs Qa4 Qa3 Qa3 Tao

Tf

Tb

Xgm

QTa1s Tao

QTa1 QTa1 Qa4

Xg

Kcb

Tdl

Xgm

Xg

Xag

Xg

Yd

Yd

Xg

Xg

Xgs

Xgp

POWELL

PEAK

FAULT

Xgl

TKq

TYd

Qa2

Qa4 Tvf

Tvf

Tvts

Tvbt

Tp

Qs

A ́

A

Base from U.S. Geological Survey, 1970

Polyconic projection; 1927 North American Datum

Geology mapped by B.E. John (1981-1987, 1990-1996); K.A. 

Howard (1980-1981, 1989-1990, 2006-2008); J.E. Nielson 

(1981-1982, 1990); J.M.G. Miller (1992-1996); assisted by V.L. 

Hansen (1981), M. Pernokas (1980), L. Glick (1982), and 

Linda Thorburn (1992)

GIS database and digital cartography by S.S. Priest

Manuscript approved for publication October 3, 2012

CALIF.

MAP LOCATION

ARIZ.

NEV.

1000 0 1000 2000 3000 4000 5000 6000 7000 FEET

1 .5 0 1 KILOMETER

SCALE 1:24 000

CONTOUR INTERVAL 20 FEET

DOTTED LINED REPRESENT 5-FOOT CONTOURS

1 1/2 0 1 MILE

APPROXIMATE MEAN

DECLINATION, 2012

113⁄4°

TKl

Yd

Tdm

TYd

Tcd

TKcd

Tdl

Tdm

TKq

TKq

Xgp

Yd

TYd

Tcd

TKcd

Tdl

Tkl

Yd

Tdm

TKcd

35

35

35

35

35

35

35

M ?

"

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v

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1

1⁄2 3

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Tmgn

Tc

Tcgn

Tmt

Tcv

Tsb

Tm

Tfb

Tst

Tp

Ts

Xag

Xg

Kt

KYg

Xgl

KYq

Yd

Yg

Xga

Xgp

Xgs

Xgm

Tv

Tvb

Tvbt

Tvt

Tvi

Tvts

Tvf

Tac

Ti

Tmi

Tdl

Tdm

TYd

Tcd

TKcd

TKl

TKq

TKf

Kcc

Kcb

Kcg

Kch

TKwq

Kd

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Trbs

Trbfm

Tbl

Tf

Tb

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QTa1

QTcg

Trbb

Trbfu

Tao

Qca

Qcs

Qcgy

Qcr

Qcm

Qtp

Qc

Qtg

Qf

LIST OF MAP UNITS

SEDIMENTARY AND VOLCANIC ROCKS AND DEPOSITS

Artificial fill (Holocene, Anthropocene)

Disturbed ground (Holocene, Anthropocene)

Dredged sand (Holocene, Anthropocene)

Piedmont alluvium

Youngest piedmont alluvium (Holocene, Anthropocene)

Younger piedmont alluvium (Holocene)

Intermediate-age piedmont alluvium (Pleistocene)

Floodplain and deltaic deposits (Holocene, Anthropocene)

Windblown sand (Holocene)

Landslide block (Holocene)

Colorado River-related deposits

Terrace gravel and sand (Upper Pleistocene)

Pink silty sand

Chemehuevi Formation (Upper Pleistocene)

Sand

Mud

Gypsiferous mud

Angular gravel

Deposits of old railway grade

Old piedmont alluvial deposits

Older piedmont alluvium (Pleistocene and Pliocene)

Deposits of ancestral Sacramento Wash

Cemented old piedmont alluvium, undivided (Pliocene and Miocene(?))

Ancestral Colorado River deposits

Colorado River gravel, undivided (Pleistocene and (or) Pliocene)

Boulder conglomerate of Bat Cave Wash (upper Pliocene(?))

Facies of Santa Fe Railway (Pliocene)

Upper conglomerate

Middle part

Lower claystone and sandstone

Sandstone and conglomerate (lower Piocene)

Bouse Formation (lower Pliocene)

Basal limestone

Fanglomerate (upper Miocene)

ROCKS DEPOSITED DURING EXTENSIONAL DEFORMATION

Upper sedimentary and volcanic sequence (middle Miocene)

Conglomerate

Gneiss-clast conglomerate

Volcanic-clast conglomerate

Sedimentary breccia

Megabreccia

Granite-clast megabreccia

Gneiss-clast megabreccia

Tuff-clast megabreccia

Sedimentary rock and tuff

Higher basalt flows

Peach Spring Tuff (early Miocene)

Sedimentary rocks (lower Miocene)

Lower volcanic sequence (early Miocene)

Basalt flows

Basalt, tuff, and conglomerate

Tuff

Volcanic and intrusive rocks

Tuff and sedimentary rocks

Lava flows

Arkose and conglomerate (lower Miocene)

INTRUSIVE AND METAMORPHIC ROCKS

Hypabyssal intrusions (Miocene)

Mafic intrusive rocks (Miocene)

Light-colored dikes (Miocene)

Mafic dikes (Miocene)

Dike swarm of Chemehuevi Mountains

Northwest-striking dikes (Miocene)

Northeast-striking dikes (Tertiary or Late Cretaceous)

Lamprophyre dikes (Tertiary or Late Cretaceous)

Quartz porphyry (Tertiary or Late Cretaceous)

Fine-grained granite (Tertiary or Late Cretaceous)

Dark dikes, undivided (Tertiary to Proterozoic)

Whale Mountain sequence of John (1987b)

Quartz monzonite (Miocene and Cretaceous(?))

Chemehuevi Mountains Plutonic Suite (Late Cretaceous)

Chemehuevi Peak Granodiorite

Biotite granodiorite

Porphyritic hornblende-biotite granodiorite

Hornblende-biotite granodiorite

Diorite (Late Cretaceous)

Diorite of Topock (Cretaceous(?))

Granite (Cretaceous or Mesoproterozoic)

Quartz monzodiorite (Cretaceous or Mesoproterozoic)

Diabase (Mesoproterozoic)

Granite (Mesoproterozoic)

Mylonitic gneiss and migmatite (Paleoproterozoic protolith)

Augen gneiss (Paleoproterozoic)

Gneiss (Paleoproterozoic)

Pegmatite and granite gneiss

Leucocratic gneiss

Amphibolite

Mixed granite gneiss and metasedimentary rocks

Contact—Dashed where approximate

Faults—Dashed where inferred; dotted where concealed (arrows show relative 

separation in cross sections)

Fault—Showing dip where known; bar and ball on downthrown side

Fault, low-angle normal—Rectangle on downthrown side

Folds—Showing trace of axial surface and direction of plunge

Anticline

Syncline

Dike—Showing dip where known. Color correlates to geologic map unit

Fluvial scarp—Hachures point downscarp

Strike and dip of beds and volcanic layers

Inclined—Showing dip

Inclined—Dip amount unknown

Overturned

Vertical

Foliation

Magmatic (including welding compaction)

Inclined

Vertical

Metamorphic

Inclined

Vertical

Mylonitic

Lineation, mylonitic

Slickenlines

Tc

Ts

Tac

Tv Tvi

Tvb

Tvts

Tvf

Tvbt Tvt

Tp

Tcgn Tcv Tsb Tm Tmg Tmgn Tmt Tst Tfb Ti

Tmi

Tdl

Kcc

Kcg

TKwq

Kd Kt

Yd KYg KYq

Yg

Xag

Xgm Xgl Xg

Xgp

Xga Xgs

Kcb

Kch

Tdm Tcd TKcd TKl TKq

TKf

TYd

CORRELATION OF MAP UNITS

SEDIMENTARY AND VOLCANIC ROCKS AND DEPOSITS INTRUSIVE AND METAMORPHIC ROCKS

ROCKS DEPOSITED DURING EXTENSIONAL DEFORMATION

Late

Cretaceous

MesoProterozoic

PaleoProterozoic

CRETACEOUS

TERTIARY

QUATERNARY

Cretaceous

or

MesoProterozoic

Cretaceous(?)

Tertiary

or

Cretaceous

Tertiary

to

Proterozoic

Miocene

and

Cretaceous(?)

PROTEROZOIC

Miocene

Pliocene

Pleistocene

Holocene

Anthropocene

Pleistocene

and Pliocene

Pliocene

and Miocene?

Unconformity

Unconformity

Qa4

Qa3

Qa2

af d ds

Qs Ql

Qf

Qtg Qtp

Qc

QTcg

QTa1 QTa1s

Tao

Trbb

Trbfu

Trbfm

Trbfl

Trbs

Tb Tbl

Pleistocene

and (or)

Pliocene Pliocene?

Qcgy Qca Qcr Qcs

Qcm

Tf

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Map 3236

Pamphlet accompanies map