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

MISCELLANEOUS FIELD STUDIES MAP MF–2353Version 1.0

SHEET 5 OF 5

Pamphlet accompanies map

GEOLOGIC MAPS AND CROSS SECTIONS OF MINE LEVELS AT THE PEA RIDGE IRON MINE, WASHINGTON COUNTY, MISSOURIBy

C.M. Seeger,1 L.M. Nuelle,2 W.C. Day,3 G.B. Sidder,4 M.A. Marikos,5 and D.C. Smith1

20011Missouri Department of Natural Resources, Division of Geology and Land Survey, P.O. Box 250, Rolla, MO 654012Doe Run Mining Company, P.O. Box 500, Viburnum, MO 655663U.S. Geological Survey, Denver, CO4Littleton, CO5University of Arizona, Department of Geosciences, Tucson, AZ 85705

Manuscript approved for publication April 10, 2001

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

This map was produced on request, directly fromdigital files, on an electronic plotter

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

A PDF for this map is available athttp://geology.cr.usgs.gov/pub/mf-maps/mf-2353

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Upper Cambrian

Middle Proterozoic

Unconformity

CORRELATION OF MAP UNITS

LIST OF MAP UNITS

Lamotte Sandstone (Upper Cambrian)

MIDDLE PROTEROZOIC UNITS

Aplite dikes

Mafic dikes

REE mineral-bearing breccia pipes

Silicified rock

Specular hematite

Hematite, undivided

Magnetite

Pseudobreccia

Magnetite-cemented pseudobreccia non-ore

Magnetite-cemented pseudobreccia ore

Hematite-cemented pseudobreccia

Iron oxide-cemented heterolithic breccia

Magnetite-cemented heterolithic breccia non-ore

Magnetite-cemented heterolithic breccia ore

Hematite-cemented heterolithic breccia

Iron oxide-cemented amphibole breccia

Magnetite-cemented amphibole breccia non-ore

Magnetite-cemented amphibole breccia ore

Hematite-cemented amphibole breccia

Magnetite-cemented breccia, undivided

Amphibole-quartz rock

Volcanic rocks

Banded rock

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Contact—Dashed where projected or inferred; jagged where extremely gradational

Fault—Showing approximate dip where known. Dashed where projected or inferred. R, reverse fault

Mine workings—Open-ended workings indicate stopes or abandoned areas

Development drill holes

Flat

Inclined up

Inclined down

Vertical—Cross sections only

Shaft location

Altered rock

Silicification and potassium feldspar alteration

Amphibole alteration

70R

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mpbo

m

m

mpbo

aqr

vr

vr

vr

mhbomhbn

mhbn

mhbo

mhbo

aqr

m

mhbn mhbo

vr

sr

N147300E94600

N147100E94800

N146900E95000 E95200

N146700

1100

1200

1300

1400

1500

1600

1700

1800

1900

2000

2100

2200

2300

2400

2500

2600

2700

dm

dm

dm

dm

dm

dm

dm

dm

dm

dm

dm

sr

aqr

m

mabo

dm

aqr

vr

sr

A A'

1,675-ft level

1,825-ft level

1,975-ft level

2,125-ft level

2,275-ft level

2,370-ft sublevel

2,440-ft sublevel

2,475-ft level

2,505-ft sublevel

2,675-ft sublevel

1,375-ft levelA A'

A A'

A

A

A

A

A

A

A

A

A

A'

A'

A'

A'

A'

A'

A'

A'

A'

DEPTH(feet)

mpbn

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h

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m

aqr

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sr

mabo

mpbo

vr

vr

vr

h

h

sr

mhbompbnaqr

vr

aqrmhbo

vr

m

aqr

N147900E95000

N147700E95200

N147500E95400

N147300E95600

N147100E95800

1100

1200

1300

1400

1500

1600

1700

1800

1900

2000

2100

2200

2300

2400

2500

2600

2700

2800

dm

dm

dm

dm

dm

dm

dmdm

dm

dm

dm

mhbn

mhbo

mabo

sr

mabo

mabn

mpbn

vr

B B'

B

B

B

B

B

B

B

B

B

B

B

B'

B'

B'

B'

B'

B'

B'

B'

B'

B'

B'

1,675-ft level

1,825-ft level

1,975-ft level

2,125-ft level

2,275-ft level

2,370-ft sublevel

2,440-ft sublevel

2,475-ft level

2,505-ft sublevel

2,675-ft sublevel

1,375-ft level

DEPTH(feet)

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h

h

h

vr

vr

vr

vr

m

m

m

aqr

aqr

aqr

srsr

sr

mmpbo

mpbn

vr

vr

vr

aqr

mpbn

mpbn

mhbo

mhbo

m

mhbn

sr

sr

vr

hpb

bph

h

hpb

vr

hpb mpbn

N148300E95600

N147900E95800

N147500E96000

N147100E96200

1400

1500

1600

1700

1800

1900

2000

2100

2200

2300

2400

2500

2600

2700

dm

dm

dm

da

dm

dm

dm

dm

dm

dm

h

m

dmbp

mpbo

sr

vr

dm

No data

DEPTH(feet)

C C'

C

C

C

C

C

C

C

C

C

C

C'

C'

C'

C'

C'

C'

C'

C'

C'

C'

1,675-ft level

1,825-ft level

1,975-ft level

2,125-ft level

2,275-ft level

2,370-ft sublevel

2,440-ft sublevel

2,475-ft level

2,505-ft sublevel

2,675-ft sublevel

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aqr

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h

h

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mabn

hpb

sr

sr

hpb

m

mhbo

mpbn

vr

sr

mhbo

sr

hhb

h

bp

br

hpb

hpb

h

h

hpb

mhbo

mpbo

h

mpbo

mhbn

m

N148100E95800

N147700E96000

N147300E96200

1300

1400

1500

1600

1700

1800

1900

2000

2100

2200

2300

2400

2500

2600

2700

2800

2900

3000

3100

3200

3300

3400

dm

dm

da

dm

dm

dm

vr

sr

mpbn

dm

dm mhbn

mhbn

mhbo

mhbo

dm

vr

srh

hpb

bp

vr

sr

vr

mhbo

mabo

aqr

mpbo

dm

sr

mhbn

mhbn

da

dm

mpbo

dm

DEPTH(feet)

1,675-ft level

1,825-ft level

1,975-ft level

2,125-ft level

2,275-ft level

2,370-ft sublevel

2,440-ft sublevel

2,475-ft level

2,675-ft sublevel

2,505-ft sublevel

D D'

D

D

D

D

D

D

D

D

D

D

D'

D'

D'

D'

D'

D'

D'

D'

D'

D'

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vr

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mpbn

mhbn

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mbu

m

hpb

N148100E96800

N147900E96800

N147700E96800

N147500E96800

1300

1400

1500

1600

1700

1800

1900

2000

2100

2200

2300

2400

2500

sr

dm

dm

dm

dm

dm

da

vr

hu

sr

aqr

mabn

mabn

mabnm

mhbo

mhbo

mabo

2600

2700

hu m mbu

vr

No data

vr

No data

No data

vr

mabo

sr

DEPTH(feet)

1,675-ft level

1,825-ft level

1,975-ft level

2,125-ft level

2,275-ft level

2,370-ft sublevel

2,440-ft sublevel

2,475-ft level

2,505-ft sublevel

2,675-ft sublevel

E E'

E

E

E

E

E

E

E

E

E

E

E'

E'

E'

E'

E'

E'

E'

E'

E'

E'

SCALE 1:2,400200 2000 400 FEET100