uranium in black shale deposits, northern rocky mountains and

Uranium in Black Shale Deposits, Northern Rocky Mountains and Great Plains

GEOLOGICAL SURVEY BULLETIN 1030-H

This report concerns work done on behalf of the U. S. Atomic Energy Commission and is published with the permission of the Commission

Uranium in Black Shale Deposits, Northern Rocky Mountains and Great PlainsBy W. J. MAPEL

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

GEOLOGICAL SURVEY BULLETIN 1030-H

This report concerns work done on behalf of the U. S. Atomic Energy Commission and is published with the permission of the Commission

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1956

UNITED STATES DEPARTMENT OF THE INTERIOR

Fred A. Seaton, Secretary

GEOLOGICAL SURVEY

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D. C. - Price 55 cents (paper cover)

CONTENTS

PageAbstract_________________.______________________ 211Introduction._____________________________________________________ 211

Purpose and location_________________________________________ 211Acknowledgments.-____ _____________________________________ 213

Field work and use and interpretation of the gamma-ray logs._________ 213Summary of the results of the investigation._________________________ 215Descriptions of selected black shale deposits._________________________ 219

Black shale at the base of the Madison limestone and equivalents. _ _ 219Black shale at the base of the Brazer limestone....________________ 230Heath shale__________________________________ 230

Literature cited___________________________________________________ 233Index. ___._____-_-_-____________________._______ 235

ILLUSTKATIONS

[Plates 14 and 15 in pocket.]

PL.AT.E 14. Index map showing black shale localities examined for ura nium, northern Rocky Mountains and Great Plains.

15. Map and sections showing thickness and radioactivity of the Bakken formation (as used by Kordquist, 1953), northern Great Plains. Page

FIGURE 51. Locations of selected wells for which gamma-ray logs werestudied____________________________________________ 214

52. Sections showing uranium content of basal black shale of Mississippian age at outcrops in the northern Rocky Mountains region.__________________________________ 229

53. Sections showing uranium content of black shale at the base ofthe Brazer limestone, Utah and Idaho __________________ 231

54. Thickness and distribution of the Heath shale in central Montana and the Heath shale and Otter formation in eastern Montana and adjacent parts of North and South Dakota.______________________________ 232

TABLES

Page

TABLE 1. Selected wells in northern Great Plains for which gamma-raylogs were studied_____-_-_-_____-_---_-_____-___-------- 216

2. Radioactivity of formations containing black shale in selectedoil and gas wells, northern Great Plains.__________________ 217

3. Analytical data and outcrops examined.____________________ 220

m

CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

URANIUM IN BLACK SHALE DEPOSITS, NORTHERN ROCKY MOUNTAINS AND GREAT PLAINS

By W. J. MAPEL

ABSTRACT

Reconnaissance examinations for uranium in 22 formations containing black shale were made in parts of Montana, North Dakota, Utah, Idaho, and Oregon in 1953. About 150 samples from 80 outcrop localities and 5 oil and gas wells were submitted for uranium determinations. Most of the black shale deposits examined contain less than 0.003 percent of uranium; however, thin beds of black shale at the base of the Mississippian system contain 0.005 percent of uranium at 2 outcrop localities in southwestern Montana and as much as 0.007 percent of uranium in a well in northeastern Montana. An 8-foot bed of phosphatic black shale at the base of the Brazer limestone of middle and late Mississippian age in Rich County, Utah, contains as much as 0.009 percent of uranium.

Commercial gamma-ray logs of oil and gas wells drilled in Montana and adjacent parts of the Dakotas indicate that locally the Heath shale of late Mississippian age contains as much as 0.01 percent of equivalent uranium, and black shales of Late Cretaceous age contain as much as 0.008 percent of equivalent uranium.

INTRODUCTION

PURPOSE AND LOCATION

A reconnaissance search for uranium in black shale in the northern Rocky Mountains and Great Plains regions was carried out during the summer of 1953 by the U. S. Geological Survey on behalf of the Division of Raw Materials, U. S. Atomic Energy Commission. The work is part of a continuing program to investigate the uranium possibility of untested or incompletely tested black shale deposits* in the Western States. Most of the localities visited are in southwestern and central Montana, central and southeastern Idaho, and north western Utah. About 150 gamma-ray logs from wells drilled for oil and gas in Montana and adjacent parts of North and South

211

212 CONTRIBUTIONS TO THE GEOLOGY OF URANIUM

"53 <a S'

nd so Mont

Ce w

-I"

II »a2'So

i i °

-

Pw >.

ccKoM g 'ac

S0 fl d 53fi 50

le le

S G

o si 'o o

URANIUM IN BLACK SHALE DEPOSITS 213

Dakota were scanned for anomalous radioactivity, and samples of drill cores or cuttings from 5 of the wells were submitted for uranium determinations. Plate 14, the index map, shows the localities visited, and the table above shows the formations examined.

Previous work by Duncan (1953) indicated that the Heath shale of late Mississippian age and a thin black shale sequence of early Missis- sippian age called variously the Bakken formation (as used by Nordquist, 1953), the shale of Kinderhook age, or the Exshaw forma tion (Warren, 1937) at some places contain abnormally large amounts of uranium. Particular attention was given to a systematic sampling of these formations in an attempt to define areas of maximum or minimum radioactivity which might then be related to facies changes, source areas, thickness, or other factors that reflect environments of deposition.

Black shale of the Phosphoria formation of Permian age is known to contain uranium in the northern Kocky Mountains region, but it was excluded from the study because it has been sampled extensively as part of a separate investigation by the Geological Survey.

ACKNOWLEDGMENTS

The present investigation is a continuation of previous reconnais sance studies made at various times since 1951 in the Rocky Moun tains region, as reported by Duncan (1953).

D. C. Duncan, R. J. Ross, J. E. Smedley, R. P. Kunkel, P. W, Richards, and H. D. Hadley supplied samples of black shale or guided the writer to exposures of shale in Utah and Montana. W. J. Hail, Jr., compiled information from the gamma-ray logs and assisted in interpreting the results of this work. Radiometric and chemical analyses listed in this report were made in Geological Survey laboratories.

FIELD WORK AND USE AND INTERPRETATION OF THE GAMMA-RAY LOGS

Outcrops of black shale described in the geologic literature or in unpublished reports available to the writer were examined for radio activity at about 80 localities. Estimates of radioactivity were made in the field using a portable scintillation detector or a Geiger counter;. At most of the localities, representative samples of the formation were collected for uranium determinations regardless of the observed radioactivity. At a few localities, however, only those parts of the formation which showed appreciable radioactivity were sampled.


Roads between outcrops were traversed with a car-mounted scintilla tion counter, and those areas with higher than average background were examined on foot with the portable instruments.

The examination of gamma-ray logs of wells drilled for oil or gas provides a convenient means of evaluating the uranium possibilities of many black shale formations which otherwise might be difficult to test because of poor natural exposures or broad outcrop areas. Gott and Hill (1953), in a study of commercial gamma-ray logs of uncased wells drilled in the Rangely field, northeastern Utah, found that, on the average, a 1-inch deflection of the Lane Wells gamma-ray curve at a 10-inch sensitivity scale is caused by about 0.0007 percent of equiv alent uranium. They pointed out that variations hi this value might be caused by such factors as the ratio of thickness to grade of the bed tested, the fluid content of the well, the shielding effect of casing in cased wells, differences in individual logging instruments, and the rate of movement of the ionization chamber. The calibration, there fore, is only approximate, but it gives some measure of the order of magnitude of radioactivity of the formations penetrated, and it is useful in comparing the radioactivity of the rocks from place to place.

Tables 1 and 2 list 15 wells drilled hi Montana and the Dakotas and indicate the average and maximum deflections on the gamma-ray logs of formations containing significant amounts of black shale. The locations of these wells are given in figure 51. Gamma-ray logs of

c A N A D A- ..__. . . - ~y

.6.9 »li V2 1Q4

^ ^ "" ! NORTHDA KOTA

MO N- "* T A A-» ... ^ )N _ . , £.5

-» S"***" "^"j Y""""" x | SOUTH ^ f .. ..__- - ~j DAKOTA

0 ^ -JN W Y O M ING

FIGTTEE 51. Locations of selected wells for which gamma-ray logs were studied (table 1).


other wells examined but not listed in tables 1 and 2 show comparable radioactivity values.

SUMMARY OF THE RESULTS OF THE INVESTIGATION

Uraniferous deposits of black shale thus far found in the northern Rocky Mountains and Great Plains regions are either deeply buried and inaccessible, or they are too thin or of too low grade to be of value at this time as a source for uranium. Only a few of the deposits contain more than 0.003 percent of uranium. Of these few, beds of black shale at the base of the Madison limestone of early Mississippian age contain 0.005 to 0.007 percent of uranium at three localities in Montana and one in North Dakota (Iocs. 43, 44, 82, and 85, pi. 14), and 4 feet of a bed of black shale 8 feet thick at the base of the Brazer limestone of middle and late Mississippian age contains 0.009 percent of uranium at one locality in Rich County, Utah (loc. 30). The analyses of samples collected at these and other localities are listed in table 3.

The evaluation of gamma-ray logs of oil and gas wells, as shown by table 2, suggests that the Heath shale of late Mississippian age locally contains 0.009 percent of equivalent uranium or more in Musselshell and McCone Counties, Mont., and that the Colorado and Pierre shales of Cretaceous age contain as much as 0.008 percent of equivalent uranium in Blaine County, Mont., and in Perkins County, S. Dak., respectively. No drill cores or cuttings from these wells were avail able for analyses, and so the actual uranium content of the shale is unknown.


s § ooong5oooooooo,,r M Q Q P §§§QQfiQfiQflQS

1

8 "^ e

5; e

a iJ3 O-a "Sai§ s

*jo a

.2 a § a g g a 22 !§ a SO »^H M » *

fp 13 p T)

a ^ 3/^*

a *5Q D

!I1 I

>> .0

§ ! "g

D a BO

C>» 0» US US*-( *-l »-H r~*CO CO CO t~

^ O O O O O O O O

us us

-2

8 S 1 1

S-a-g-a 1 s| a M~a l-ag-ao «I^ g'a^'a | a-g-al-a^s h g «3_g eyg a|ii feis.gis'Shlii 2^5^ 8 a.o^'S^ajSgSgggrtg^gtf^SgSI^

D5QEQDDDDOOD5QDD

S ^« * "H o a O

P og flW .2

^§-"3:sgf

3 13W gH 9i I

s e^i ?y ^ 2g£!? 8 SSs|S

PH e

H ° I a)Bas «M^J o> 73to w D

rt< «C CO

fl -3§ O g85 g

P? §a -8 o> o , 85 Q3 1~I M

p -a*$E? §POO

_ O)

i 1 i5 £ ^-2 p' 1 28iw'

®Vri,

§^1

OO O5 O i-l


TABLE 2. Radioactivity of formations containing black shale in selected oil and gas wells, northern Great Plains

Well no. (fig. 51) Rock unit

Depth (feet)

From To

Thick ness of unit (feet)

Gamma-raydefle Jtion.

converted to sensitivity of

10 (inches)

Average

Maxi-

Depth in well of

maximum deflection

(feet)

Estimated maximum

eTJi (percent)

Cretaceous rocks

1

2

4

5

6

7

9

11

12

13

14

Pierre _______

Greenhorn ______Belle Fourche ..........

Skull Creek............Cloverly ...............Colorado _______KootenaL. ............Claggett . ...........EagleColorado _______KootenaL- ............Pierre . ..............Niobrara _______Greenhorn .............Carlile .Belle Fourche .......Mowry ._.._.__...._...Muddy and Skull

Creek, undivided .... Cloverly ...............Colorado _______

Colorado ..........Kootenal ..............Colorado _______Kootenai ..............Claggett and younger. . Eagle _________Niobrara _ . ___ , ....Frontier and Mowry,

undivided.. .........Skull Creek....... .....Kootenai _ ...........Claggett.-.. ...........Eagle -.........-.-.-...

Greenhorn .............Belle Fourche ____ .

Kootenai ..............

Eagle.- ________

Greenhorn and Belle Fourche .............

Bow Island (of Perry, 1937).................

Greenhorn, Belle Fourche, and Mowry.

Skull Creek .........

2002,1602,7882,9153,4603,7103,8501,1173,032

0396807

2,5771,1352,368

| 2,928I

3,705 3,945

2001,484

01,030

02,449

0 955

1,390

1,8422,6172,7641,5251,9502,1503,0503,2503,4303,900

8801,5502,020

2,503

3,105600

2,560

3,044 3,6053,853

2,1602,7882,9153,4603,6803,8504,1002,9523,273

396807

2,4722,9032,3682,928

3,705

3,945 4,3651,4261,9901,0301,6022,4492,724

955 1,3901,842

2,5852,7643,1481,9502,1503,0503,2503,4303,5904,0941,5502,0202,503

3,105

3,7372, 5603 044

3,605 3,8534,037

1,960628127545220140250

1,835241396411

1,665326

1,233560

777

240 420

1,226506

1,030+572

2,449+275955+ 435452

743147384425200900200180160194670470483

602

6321,960

484

561248184

3.03.73.63.73.13.42.64.82.33.04.14.93.12.23.0

3.3

3.0 2.45.03.22.72.26.04.42.0 3.54.0

3.33.53.02.73.03.43.74.13.73.43.44.65.1

5.1

4.24.85.0

6.20.84.7

4.85.74.75.74.94.03.77.38.05.15.78.05.03.44.5

5.8

4.0 4.38.26.04.54.5

10.96.73.3 4.26.7

5.94.25.76.13.65.75.86.65.44.44.66.57.7

7.4

6.011.08.5

10.0 9.26.7

1,8992,2102,8603,3353,5403,8113,9082,1613,151

319805

1,6292,7382,2552,900

3,469

3,935 3,9556412

1,890200

1,3311,1832,498

1,3191,405

2,0292,6992,8811,8582,0193,0383,2463,3483,5253,9291,3882,4602,760

2,800

3,4882,2122,560

3,480 3,610

3,872,3,895

0.003.004.003.004.003.003.003.005.006.004.004.006.004.002.003

.003

.003

.00&

.004

.003

.003

.008

.005

.002

.003

.004

.004

.003

.004

.004

.003

.004

.004

.005

.004

.003

.003

.005

.005

.005

.004

.008

.006

.007

.006

.003

' 1-inch deflection=0.0007 percent eU on 10-inch sensitivity scale.


TABLE 2. Radioactivity of formations containing black shale in selected oil and gas wells, northern Gr'eat Plains Continued

Well no. (fig. 51) Rock unit

Depth (feet)

From To

Thick ness of unit (feet)

Gamma-raydeflection,

converted to sensitivity of

10 (inches)

Aver- Maxi-

Depth in well of

maximum deflection

(feet)

Estimated maximum

eTJi (percent)

Jurassic rocks

12456

1011121314

Morrison ...................do... ............... do.. .......... do-,...... .. do..... do.. . ......do....... ........... .do................. .do..... ........ do-

4,100

1,9904,3655,6003,1484,3153 717

4,037

4,1803,4733,1202,2454,4056,0023,1624, 6553,7604,116

80200217255

40402

14340

00

7Q

3.63.33.13.81.83.43.33.72.75.3

6.68.54.76.42.44.13.73.93.16.2

4,1183,4002,9222,2394,4005,6613,1554,4913,7384,088

.005

.006

.003

.004

.002

.003

.003

.003

.002

.004

Mississippian and Pennsylvania!! rocks

Minnelusa______.Amsden.....____.Big Snowy group......Amsden of local usage..Heath_..............Amsden of local usage- Heath..................Amsden of local usage..Heath.................Minnelusa___._.Amsden_______.Big Snowy group__.Heath............Otter....__._.__.Amsden.___.___.Heath and Otter for

mations, undivided..Amsden._______.Heath and Otter for

mations, undivided..Bakken (as used by

Nordquist,1953)_ .Big Snowy group__.Englewood_____.Heath and Otter for

mations, undivided..Bakken (as used by

Nordquist, 1953).....

5,7005,8706,0704,0174,2333,5503,7473,6043,9765,8206,2306,3742,8173,0505,650

5,7556,996

7,437

4,9405,1826,495

6,900

9,613

5,8706,0706,3724,2334,3253,7473,800+3,9764,6226,2306,3747,1183,0503,3955,755

5,9907,437

7,929

4,9765,4326,570

7,340

9,721

170 200 302 216

92 19753+

372 646 410 144 744 233 345 105

235441

492

36250

75

440

108

3.1 2.7 2.9 1.3 2.7 2.2 3.2 2.4 3.0 1.8 1.8 2.7 3.0 3.0 2.3

2.5 2.3

2.9

5.85.8 6.0

4.6

9.0

7.1 5.3 4.0 4.8 4.7 4.3 5.9 8.5

12.7 3.6 3.6 7.5 6.6 8.4 4.7

15+5, 5.7

9.5

8.99.0 8.8

7.8

5,8705,9036,1184,1369,2803,5583,7503,9304,0456,2276,3566,5502,9403,1695,745

5.767, 5,7757,304

7,529

4,9715,3586,504

7,005

13+9,625, 9,700

Devonian rocks

78

1314

15

Three Forks ............... .do .............. do... . Devonian, undifleren-

tiated.. _ .Qu'appelle group (of

Baillie, 1953)

2,7807 oqn

4,976

6,570

9,724

3,1308 0305,030

6,822

9,916

35010054

252

192

1.54.85.1

3.7

3.7

6.36.26.9

8.0

6.0

3,0067,9725,008

6,715

9,798

.004

.004

.005

.005

.004

Ordovician rocks

5131415

Winnipeg (upper part). do.... _ . ___ ... do. .... .do...... .... .......

9,5206,2859,527

13,395

9,6626,3129,666

13, 562

14225+

139167

7.89.26.66.3

10.610.010.48.0

9,5356,3099,635

13,453, 13,466

.007

.007

.007

.004

11-inch deflection=0.0007 percent eTJ on 10-inch sensitivity scale.


DESCRIPTIONS OF SELECTED BLACK SHALE DEPOSITS

BLACK SHALE AT THE BASE OF THE MADISON LIMESTONE ANDEQUIVALENTS

A black shale sequence of early Mississippian (Kinderhook) age, which ranges in thickness from a few inches to as much as 100 feet, occurs locally at the base of the Madison limestone or its equivalents in southwestern and central Montana and in the Williston basin of Saskatchewan, Manitoba, Montana, and the Dakotas. The term "Bakken formation" has been used to identify this unit in the subsurface in the Williston basin, where it is described by Nordquist (1953, p. 72) as mainly "two thin highly radioactive black shales separated by a grey calcareous sandstone, siltstone, or dolomite." According to Nordquist, the upper shale unit may be correlative with a bed of black shale, a few inches to 30 feet thick, which occurs at the base of the Madison or Lodgepole limestones in various parts of southwestern Montana and Utah. The lower shale and medial sandstone-dolomite units may correlate with the Sappington sandstone as used by Holland (1952), a shale and sandstone sequence as much as 60 feet thick, which occurs below the Madison limestone in parts of southwestern Montana. In southern Canada, equivalents of the basal shale unit and medial sandstone-dolomite unit of the Bakken formation, as used by Nordquist (1953), are regarded by him to correlate respectively with the Exshaw shale (of Warren, 1937) and the basal sandstone of the overlying Banff formation (of McConnell, 1887). In most parts of the northern Rocky Mountains region, the Bakken formation (as used by Nordquist, 1953) and its equivalents unconformably overlie the Three Forks or Jefferson formations of Late Devonian age, and they are conformably overlain by limestone of the Madison or Lodge- pole formations, or McConnell's Banff formation, all of early Missis sippian age.

TAB

LE 3

. A

naly

tica

l da

ta a

nd o

utcr

ops

exam

ined

[n

. d. c

., no

t det

erm

ined

che

mic

ally

]

Loc

al

ity

no.

(pl.

14)

Loc

atio

n (S

ec.,

T.,

R.)

Roc

k un

itL

abor

a

tory

sa

mpl

e no

.

Equ

ival

ent

uran

ium

(p

erce

nt)

Ura

nium

(p

erce

nt)

Des

crip

tion

Q O

Frec

ambr

ian

rock

s: I

daho

4 5 6 7 8 9

25-4

6N-2

W.

27-4

8N-2

W.

21-4

9N

-1W

....

. --.. . - ..,

3 an

d 4

-48

N-3

E.

12

-49

N-4

E..

... .

....

....

....

....

....

14-4

9N-5

E. .

....

....

....

. ...... .....

....

.do

....

...

... .

.do

..... ..

.. . .

..

.... .d

o..

..

..

. ...

...

..

do.......

.do...

9850

3

9850

6

0.00

1

0) 0) (0

.002

(n. d

. c.)

(n. d

. c.)

Frec

ambr

ian

rock

s: M

onta

na

32 33 48 49

22-1

4N-4

W.

36-13N-6W.....

. ... .

....

....

. ..

....

.

30-7

N-4E

. 20-7N-5E.... ...

_...

.

.........

... ..do-.. ..

. ..

. .

..do ..

.

94788

9415

0

9416

1

94162

0.00

2

.001

.002

.004

(n. d. c

.)

(n. d. c

.)

(n. d.

c.)

0.00

3

cuts

.

w

Ous

ter

Co

un

ty._

..,

SWJ4

-16-

13N

-18E

.

Bea

r L

ake

Cou

nty.

12-1

38^4

2'E.

O

neid

a C

ounty

....

35-1

4S-3

6E.

Cam

bria

n ro

cks:

Ida

ho

Gar

den

Cre

ek p

hyll

ite

.. d

o........ - .

Spen

ce s

hal

e...

.. -.

.do... .

9704

4 0.

003

(n.

d. c

.)

9704

5 .0

03

(n. d

. c.

)

9702

4 .0

02

(n.

d. c

.)97

023

.002

(n

. d.

c.)

9704

2 .0

03

(n. d

. c.)

9704

3 .0

03

(n. d

. c.

)

Cha

nnel

sam

ple,

2-f

t bed

of d

ark-

gray

to b

lack

phy

lllt

ene

ar m

iddl

e or

120

-ft e

xpos

ure.

G

rab

sam

ple,

bla

ck p

hyll

ite

cont

aini

ng d

isse

min

ated

pyri

te a

nd c

halc

opyr

ite,

colle

cted

fro

m m

ine

dum

p.

Gra

b sa

mpl

es, u

pper

and

low

er p

arts

of

60-f

t ex

posu

reof

dar

k-gr

eeni

sh-g

ray

shal

e.

Gra

b sa

mpl

es, u

pper

and

mid

dle

part

s of

30-

ft ex

posu

reof

dar

k-gr

eeni

sh-g

ray

argi

llite

.

Cam

bria

n ro

cks:

Uta

h

25 28

Cac

he C

ount

y.. _

__________ -

10-1

4N-2

E.

SW

J4-4

-11

N-4

E.

.-..

_..

._..

-.-

..d

o.. . _ . --.

.. _

.

9703

997

040

9704

1Q

7A

QQ

0.00

3.0

01

.002

f\f\

K

(n. d

. c.)

(n. d

. c.)

0.00

3

of d

ark-

gree

nish

-gra

y sh

ale.

shal

e, lo

wer

par

t of 1

0-ft

expo

sure

.

Cam

bria

n ro

cks:

Mon

tana

39

46N

WJ4

-14

-3S

-5W

. B

road

wat

er C

ou

nty

. , _____ .

22-5

N-1

W.

9701

2

9479

0

0.00

5

.002

0.00

1

(n.

d.

c.)

dG

rab

sam

ple,

nea

r m

iddl

e of

50-

ft ex

posu

re o

f gre

enis

h-

M

blac

k si

lty s

hale

. >

C

hann

el s

ampl

e, 6

-ft b

ed o

f bl

ack

shal

e, u

pper

par

t of

^

50-ft

exp

osur

e.

£}

3O

rdovic

an r

ock

s: I

dah

oH

12

13 14

15

NE

J4-2

8-1

1N

-17

E.

5-1

1N

-17

E. ..._

_ _

.

SW

^-24-1

0N

-17E

. U

nsu

rvey

ed 15

mil

es n

ort

hea

st o

f K

etch

um

.

Satu

rday

Mou

ntai

n fo

rmat

ion.

. .

....

.do . ....-.. ..

9704

6

9704

7

9705

2

9705

3

0.00

3

.003

.003

.003

(n.

d.

c.)

(n. d

. c.)

(n. d

. c.)

(n. d

. c.)

^\

Chi

p sa

mpl

e, m

iddl

e 10

ft o

f 30-

ft be

d of

dar

k-gr

ay sh

ale.

^

Thi

n-be

dded

bla

ck d

olom

ite a

nd i

nter

bedd

ed b

lack

^

shal

e ex

pose

d in

mai

n ad

it of

the

Red

bird

min

e fo

r a

x

dist

ance

of 1

,000

ft.

w

Gra

b sa

mpl

e, lo

wer

par

t of

200

-ft e

xpos

ure

of d

ark-

gray

^

to b

lack

thin

-bed

ded

argi

llit*

. M

C

hip

sam

ple,

top

25-

ft of

1,7

00-ft

ex

posu

re

of b

lack

M

ar

gilli

te.

t!

Chi

p sa

mpl

e, 1

0-ft

bed

near

mid

dle

of 1

,700

-ft e

xpos

ure

M

of b

lack

arg

illite

. ^ y

O

rdo

vic

ian

ro

cks:

Uta

h

y w

26

27N

WJ4

-5-1

4N

-4E

. N

EU

-18

-12

N-3

E... .

....

....

....

....

.....d

o.... ..

....

......

....

....

....

9702

6 97

024

9703

1

0.00

4 .0

04

.003

0.00

3 .0

03

.003

0

Gra

b sa

mpl

es, u

pper

and

low

er p

arts

of 4

5-ft

expo

sure

CO

of

ver

y da

rk g

ray

nonc

alca

reou

s sh

ale.

S

C

hann

el s

ampl

e. 3

-ft b

ed o

f no

ncal

care

ous

dark

-gra

y m

> Not

sam

pled

.

to


§o"S

e 73 8 1

II S 1

^3 %§ *O 13

3 S S a.

£3

alen um

^ *

a"-.3 CD

|a

WOO

B5B

III

33

..H Q>o

Igs3o^T-i §§£§Isls«

woo a>t"5^-25<N flC

O M

8f a

IpO

.y

"8

t3

Si8"aen -H

. . * i j * t*» $ ..£,&&£ a fi ® w_> to co C

fl-So SSSlO EHfcfcfcpq

6§ 666 dcJ'd'd'd

sB BB^

CM r. CM n COo oo oo oooooo

I1I1I

Ig

1

jp»l-l

1.°i110

S

Io£JM

.-4O

4300"3

43e>»ft oa

<D

1»

al »fl sSd^d as85^3 fl^=

D

§o

1

t~

1C3

?M^

|

&

S«3 852

5

1

CDe>»

d d 8 'S

C! -Cfo> o>

3 ."3.- Ss 3 fflP C3 d OS

O 0

§ §42 49

*Sfi Sec dgOTS°P*^oS

\Lm\Lid i W T §i3.S^ Sfe-'SW |ll§ 3 O

M< "5CO CO

36 37 38 40 41 42 43 43 44 61 64 65 78 79 80 81

82

NE

M-5

-7N

-12

W....... .

............

SW

Ji-4

-7N

-12W

....

....

....

........

NE

M-3

4-9S

-8W

.

NE

M-1

3-3S

-5W

.

NW

M-1

6-1N

-2W

.

11-1

1&-3

E.

SW

M-2

6-2N

-2E

. ...................

....

...d

o..

....

....

....

....

....

....

....

.

8E

J£-2

-2N

-2E

_..

....

___ .

_._

._.

9-13

N-1

7E.

SW

J£-8

-12N

-18E

._ _

-_._

_____ .

32-1

2N-1

9E. .

....

.. .................

5-25

N-2

4E.

2-26

N-2

4E.. ..

....

....

....

....

....

..22

-26N

-25E

. ...

....

....

....

....

....

.D

anie

ls

Cou

nty,

SW

>/4-

12-3

6N-4

7E

(Car

ter-

Dan

iels

on w

ell 1

).

Roo

seve

lt C

ount

y, N

Ei/i

-2-2

8N-5

1E,

(Mur

phy

and

othe

rs-E

ast

Popl

ar

wel

ll).

....

.do-.

..-.

-.-.

. _

__

... _

_

....

. do..

....

....

.. ..

....

....

....

..

-.-d

o..

....

... .

....

....

....

....

..

.....d

o..............

....

....

....

..

-.-.

do..

....

....

....

... .

..........

.....d

o..............

....

....

....

..

Hol

land

, 195

3).

....

.do

....

.......

..............

... .

.do

....

...

....

....

....

....

.. do . ._..

d

o... ...... ..

....

....

....

.....d

o.... ..

....... .

....

. .........

Bak

ken

form

atio

n (a

s us

ed b

y N

ordq

uist

, 19

53).

.....d

o..... . .. ..

....

. .

9415

3 94

154

9415

1

9415

297

015

9701

6 97

013

CU

14S

9414

7

9701

1

9413

9 94

140

9414

1 94

142

9414

3 94

144

9414

5

9415

5 94

156

9415

7 94

158

9415

9 20

1460

9417

694

764

2014

57

2014

58

2040

65

2040

66

2040

67

2040

68

2040

69

2040

70

9851

8 98

519

.002

.0

03

.001

.002

.005

.004

00

4

ft(V

>

.003

.002

.004

.0

04

.003

.0

02

.003

.0

02

.006

.006

.0

07

.008

.0

06

.004

00

4

.004

.004

.003

.004

.003

.006

.0

05

.010

.0

07

.008

.0

03

.006

.0

04

(n.

d. C

.) (n

. d.

c.)

(n.

d. c

.)

(n.

d. c

.).0

03.0

03A

ftl

(n.

d. c

.)

(n.

d. c

.)

(n.

d. c

.)

.002

.0

05

(n.

d. c

.) (n

. d.

c.)

(n.

d. c

.) (n

. d.

c.)

.002

.002

.0

01

.003

.0

01

.005 r\f\

n

.002

.002

(n. d

. c.)

002

(n.

d. c

.).0

02

.002

.0

03

.004

.0

04

.002

.006

.0

02

Top

4V£

ft.

Bot

tom

6 f

t.

Bro

okly

n m

ine.

nonc

alca

reou

s B

lack

sha

le.

gray

lim

esto

ne,

5-ft

expo

sure

. C

hann

el s

ampl

e, t

op I

V^-

ft of

20-

ft be

d of

dar

k-gr

ay

shal

e an

d br

own

shal

y si

ltsto

ne.

gray

lim

esto

ne,

3-ft

expo

sure

.

shal

e:

Top

1 f

t. B

otto

m \yz

ft.

Top

2 ft

. N

ext

2 ft

. N

ext

2 ft

. B

otto

m \yz

ft.

Cha

nnel

sam

ple,

1-f

t bed

of d

ark-

brow

nish

-bla

ck s

hale

, ba

se o

f Sa

ppin

gton

san

dsto

ne.

Top

3 f

t. N

ext

2 ft

. N

ext

2 ft

. N

ext

2 ft

. B

otto

m 1

ft.

Dep

th 6

,964

ft.

Dep

th 6

,966

ft.

Dep

th 6

,968

ft.

Dep

th 6

,970

ft,

pyri

tic.

D

epth

6,9

71 f

t, py

riti

c.

Dep

th 6

,974

ft,

som

e li

ght-

gray

cal

care

ous

lam

inae

.

Dep

th 7

,165

-7,1

75 f

t. D

epth

7,1

90-7

,200

ft.

a § hj

O OJ

GO

' Not

sam

pled

.C

O


33)

3.3a02

ig3 ~s Ia, §I -si «3 S

1 13 §3 «w o

! J3 .J 'o2 r5

3iS3

0

da< <

a.2'n'g

Sft

§«'3 §

£ !

J s^

111l^do5 ** (fl

Hi

'3

S

80

«

«8?

CO

Location (

"§ rt 1-1

5e

1A fi

1

!§*gJ"*» .1u.4)^

3

fD

^ a a033

CO

ge

Drill cuttings, noncalcare

Depth 9,620-9,630 ft. Depth 9,700-9,710 ft. Depth 9,710-9,720 ft.

ill0

111o

ill

??

im03^^

CO*

"-3S

a _ 4J

«w "3I"i"rtZpq

||

j3

^|rilliams Count* 95W (Amerada-

1).|£

00

e

iw441§ & J""1

§«p,j^

CD

2 Aijos

i i a I>» ^

Grab sample, black chert Grab sample, 3-ft bed of <

o d d -d

S 5

i sO

§ S

a

1

|

I -i£

aribou County.. SE1/4-33-7S-10E ear Lake Counti

NE1/4-23-12S-W

D pq

(3 ?J

|a S

1Sm.S55

§

i[^

'I 2 -c( 2 pCD ft rO ^

a | § | |t> «H 03 OJ boj o CJ g °*

g .a g g °

l?l §^ 1 J S O *Q ^ O *t^

S^jwS'g £ ""S C3 r<i aft ® O

Chip sample, 10^-ft bed i taining thin lenses of bl Channel sample, middle : shale and shaly black 11 Channel sample, 2^-ft

brown shale.

Channel sample, 2-ft bed

shale.

Chip sample, upper half

black shale.

"e? g S S S o o o o13 0

3.

§ i i i ie5

oo os o .-j egi 1 i 1 CN CM CN

CDsOCO

Is2«

!!Pn

g

OJ

e

91

1eJS"g.*35 son

QQ

§

I

| 5

^ _rt

Jd u^ §

3 si is s g -a

Grab sample, 1-ft bed of ( Grab sample, 10-ft bed of c

d d d t3

3 B

<N CO

o

t-H Oo> 25

1

1 §SB

>. ft

roadwater Coun SEV4-29-3N-2E, roadwater Coun

5, 7-4N-3E.

M M

9 ft

70 73

14-9

N-1

0E.

SW1/

4-3-

16N

-10E

.N

EV

4-2-

16N

-10B

... ................

6-15

N-1

2E_.

__._

_. .

..............

, N

E1/

4-11

-14N

-11E

. .................

NW

>/4-

19-1

4N

-12E

_

._

_ _

2&

-12

N-1

4E

.. ....... _

______

21-1

1N-1

5E. _

_ . _

__________

Whe

atla

nd C

ount

y __________

5-10

N-1

3E.

7-10

N-1

3E.. ______________

._ d

o - _

___

7-13

N-1

8E.

NW

Ji-2

3-1

3N

-17

E _ _

.

.....d

o.. . ... _.._..-

6-12

N-2

0E.. ______________

. _ .do-. _

_

SW

M-3

0-16

N-1

9E...

. ________

SW

J£-1

4-15

N-1

9E. .

....

....

....

....

17-1

4N

-2IE

....... _

_____ ..

__

SE

&-3

0-H

N-2

1E

.. ..

. ...

....

....

NE

^-8~

13N

-21E

. ........... _

....

..S

W^-

17-1

4N

-21E

..,_

i __

__

__

_

6W

M-1

6-1

4N

-22

E..

.. _

_ . .

.......

.....d

o.......... ..

....

....

....

....

. .d

o............

....

. ..

....

....

... d

o..

....

....

......

....

....

....

.....d

o... .

.... ..

... .

....

.. ..

....

. ......d

o.... ..

....

....

....

....

....

.... do

....

.do..

.. ..

....

....

....

. ...

....

..

....

.do..

....

....

. .

do .

__._

Otte

r fo

rmat

ion __

__

__

__

__

....

.do

.. _

__

_

So-c

alle

d A

msd

en f

orm

atio

n of

loca

l usa

ge.

- _

do.

do. _

.

__ .

,. .

.. ..

do

...

..

....

.. ..

d

o

.. ...

..

.

loca

l usa

ge.

9416

3

9477

894

779

9478

094

781

9477

3

9477

194

772

9476

694

765

9478

3

9478

594

784

9417

7

9417

394

174

9417

594

755

9475

6

9475

7

9475

8 94

759

9476

0

9476

1 94

762

9478

6

9416

9

9417

8 94

179

9418

2 94

183

9418

4 94

185

9418

0

9419

2

.002

.002

.002

.004

.001

.003

.002

.001

.0

01.0

03.0

01

.002

.003

.002

.003

.004

.0

04.0

01

.001

.001

.002

.0

01

.003

.003

.0

06

.001

.004

.003

.0

02

.002

.0

02

.003

.0

01.0

03

.002

(n.

d. c

.)

(n.

d. c

.)(n

. d. c

.)0.

002

(n. d

. c.)

.002

(n. d

. c.

)(n

. d.

c.)

.002

(n. d

. c.)

(n. d

. c.)

.002

(n. d

. c.)

(n. d

. c.

).0

03

.003

(n. d

. c.)

(n. d

. c.)

(n. d

. c.

)

(n. d

. c.)

(n. d

. c.)

.002

.003

.0

03

.003

(n. d

. c )

(n. d

. c

)

n. d

. c )

n. d

. c )

n. d

. c

)

(n. d

. c )

(n. d

. c.)

Cha

nnel

'sam

ple,

3-f

t bed

of f

ossi

lifer

ous

blac

k sh

ale.

Cha

nnel

sam

ple,

2J4

-ft b

ed o

f gyp

sife

rous

bla

ck s

hale

. C

hip

sam

ple,

12-

ft be

d of

cal

care

ous

blac

k sh

ale.

C

hip

sam

ple,

20-

ft be

d of

non

calc

areo

us b

lack

sha

le.

Gra

b sa

mpl

e, 3

0-ft

bed

of b

lack

sha

le.

Chi

p sa

mpl

e, c

alca

reou

s bl

ack

shal

e in

terb

edde

d w

ithgr

ay li

mes

tone

, 30-

ft ex

posu

re.

Chi

p sa

mpl

es, t

op 6

ft o

f 60-

ft ex

posu

re o

f bla

ck "s

hale

. B

otto

m 6

ft o

f uni

t abo

ve.

Cha

nnel

sam

ple,

2-ft

bed

of c

alca

reou

s bl

ack

shal

e.

Gra

b sa

mpl

e, m

iddl

e of

40-

ft be

d of

bla

ck s

hale

. G

rab

sam

ple,

6-ft

bed

of b

lack

sha

le.

Gra

b sa

mpl

e, 5

-ft b

ed o

f non

calc

areo

us b

lack

sha

le.

Gra

b sa

mpl

e, 4

-ft b

ed o

f non

calc

areo

us b

lack

sha

le.

Gra

b sa

mpl

e, 5

-ft b

ed o

f cal

care

ous

blac

k sh

ale.

Cha

nnel

sam

ple,

5}^

-ft b

ed o

f cal

care

ous

blac

k sh

ale.

C

hann

el s

ampl

e, 4

-ft b

ed o

f cal

care

ous

blac

k sh

ale.

G

rab

sam

ple,

2-ft

bed

of n

onca

lcar

eous

bla

ck s

hale

. G

rab

sam

ple,

20-

ft be

d of

mar

oon

shal

e.

Cha

nnel

sam

ple,

top

4 f

t of

5-ft

bed

of

nonc

alca

reou

sbl

ack

shal

e.

Cha

nnel

sam

ple,

top

4 f

t of

30-

ft be

d of

non

calc

areo

usbl

ack

shal

e.C

hann

el s

ampl

e, m

iddl

e 4

ft o

f sam

e un

it a

s ab

ove.

C

hann

el s

ampl

e, b

otto

m 4

ft o

f sam

e un

it a

s ab

ove.

C

hann

el s

ampl

e, t

op 3

ft o

f 25-

ft be

d of

cal

care

ous

silty

blac

k sh

ale.

Gra

b sa

mpl

e, m

iddl

e pa

rt o

f uni

t ab

ove.

C

hann

el s

ampl

e, t

op 6

ft o

f 70-

ft be

d of

cal

care

ous

silty

blac

k sh

ale.

G

rab

sam

ple,

dar

k-gr

ay n

onca

lcar

eous

sha

le fr

om m

ine

dum

p.G

rab

sam

ple,

3-ft

bed

of b

lack

sha

le.

Cha

nnel

sam

ples

, 15-

ft be

d of

non

calc

areo

us b

lack

sha

le:

Top

V4

ft.

Nex

t 1

ft.

Cha

nnel

sam

ples

, 15

-ft b

ed o

f cal

care

ous

blac

k sh

ale:

T

op 2

J^ ft

. N

ext V

/z ft

. B

otto

m 6

ft.

Gra

b sa

mpl

e, 1

0-ft

bed

of b

lack

non

calc

areo

us s

hale

. C

hann

el s

ampl

e, b

otto

m 2

ft

of 3

-ft

bed

of c

alca

reou

sbl

ack

shal

e.

Gra

b sa

mpl

e, 4

-ft b

ed o

f non

calc

areo

us b

lack

sha

le.

a 8 CO to

to


g3Bd0J3S

chemically]

i ^1 S^ ©S rQ

§ a8 a3 cls * * ^-^ H

|«

5

0

3£)«!-i

}

If

^ft

Equivalent uranium (percent)

l^dis i fl

i_2§p?

£03

qo

il

i_c

intana Com

i

1§ai1§a,*

2 J2 -+JO o ^qj qj bO

r-4 * O

S S -d

1 1 1| s .a;W +a «0

M "* ' §

a «-i cs ® o PI

1h

ao

5

1 ..o !1 2o _^

+* » S> « la& & a 5**Lj W O ^ t>i

» fe ^ i»r *ft £. o Q. ** t->. & i iiliL^Ijlflpl'iiil2l2iNS|3»«>-3'a -3<a >t %'£&aaa ,Q C3,Q C3,Q C3S SJ3-W+?-"2S2S2&§o !5 aaa O O 0 £ fiQfifi

cj o o

mo ° ° JT*

oo oo c£^ r-H ^

Cb eft eft

O a

I 'S

e

"3 wfg |i-2 §fl§ Va£2 iSV « 0^ 4,|S ^ S® «

PH

c c

OOO

SINCOCOOOO 000

?2t22!

1^ ^

5 i * 5.>> we?

§ ^|

>* I &® P-? O

S3 W

> ^12 Soo d^

S g fc S

c

|OM

2£

IM

11a§K ***

itW| M'

Tay and dark-greenish-gray ai ad cuts and at natural exposure

lactivity. is above. is above.

£ «^ o> v

£S~ ^ cl S Q CQCQ

£ S£

Isg>sfflQ

3 c ca re reH

P

t« 4

If tlDCQ OD 1N r-lCQ

jS4i cict«co co

rt INTO

rt

OSS c oS

jiun

I

C3 f> Q ^

V °3 S* H "§« .-§ .-g>rt S § '^"firS

s i! ll-s .* ? 3 ^3 ^s*a> § §3 ^ rH'O §

sample, near middle of 60-ft t ninous shale (top of the sequen el sample, bottom IJi ft of sar ample, ^-ft bed of dark-gray 1 el sample, 1-ft bed of light-yello ample, 4-ft bed of black bitumi el sample, top 3 ft of 25 ft b< ninous shale (base of the sequel

jaSy-OonftS-S 23,a 2t5.a3.a2 O DO ODD

o do So **rci rcjrrj o ' «'

S S3. fl

O OO OOO O OO OOO

0

00 C»0 ^JNW

§ oiiig olo?S

a ao"2CO§ 3o

i"0*7d^2T§CO

53 74

Judi

th B

asin

Cou

nty _________

1-16

N-1

1E.

Ferg

us C

ou

nty

....

__________

NW

^-20

-14N

-24E

.

....

.do..

....

.....................

....

.do

....

....

....

....

....

....

...

9477

7

9477

6

9477

5

9477

4

9418

9

.005

.002

.002

.002

.002

.003

(n. d

. c.

)

(n. d

. c.

)

(n. d

. c.

)

(n. d

. c.

)

uppe

r pa

rt o

f 25

-ft

bed

of y

ello

wis

h-gr

ay b

ento

nite

. C

hann

el s

ampl

e, b

otto

m I

tf f

t of

25-

ft be

d of

yel

low

is

h-gr

ay b

ento

nite

. G

rab

sam

ple,

^-f

t be

d of

gra

y si

licif

ied

shal

e, u

nder

- ly

ing

bed

of b

ento

nite

des

crib

ed a

bove

. C

hann

el s

ampl

e, 4

-ft

bed

of d

ark-

gray

sha

le,

unde

r

lyin

g un

it a

bove

.

mid

dle

of a

30-

ft ex

posu

re o

f in

terb

edde

d sh

ale

and

yello

wis

h-gr

ay s

ilty

san

dsto

ne,

base

of

the

Col

orad

o sh

ale.

1 Not

sam

pled

.

to


The black shale sequence at the base of the Madison limestone was sampled at 17 localities in the mountainous parts of southwestern aad central Montana and northwestern Utah. Sections at 10 of these localities are shown in figure 52. The maximum observed uranium content of the sequence is 0.005 percent, in the lower half of a 2K-foot- thick bed of black shale near Three Forks, Mont. (loc. 43), and 0.005 percent in the basal part of a 10-foot bed of brownish-black shale nearby (loc. 44).

The Bakken formation (as used by Nordquist, 1953) was sampled in three wells, two of them in northeastern Montana and the third in northwestern North Dakota. Drill cuttings representing 30 feet of black shale from one of the wells, Amerada Petroleum Corpora tion-Harry Bakken well 1, Williams County, N. Dak. (well 15, table 1), contain 0.005 to 0.007 percent of uranium. A sample of drill core from a 10-foot-thick bed of black shale in the C. H. Murphy, Jr., and others-East Poplar well 1, Koosevelt County, Mont., sec. 2, T. 28 N., K. 51 E., contains 0.006 percent of uranium. One of six samples of drill core from a 10-foot-thick bed of black shale in the Carter Oil Company-S. W. Danielson well 1, Daniels County, Mont., sec. 12, T.36N.,K.47E., contains 0.004 percent of uranium. The samples from this well are anomalous in that they are decidedly out of balance in favor of equivalent uranium, as indicated in the following table:

Descriptions of samples: Carter Oil Company-S. W. Danielson well 1, DanielsCounty, Mont.

Sample no.

204065 204066 204067 i .- -204068 204069 .. -.204070

Depth (feet)

696469666968697069716974

Description

- do. - - . . --

laminae.

eU (percent)

0.006.005.010.007.008.003

U (percent)

n fin?.002.003.004.004.002

i J. N. Rosholt, Jr., U. S. Geological Survey Trace Elements Laboratory, investigated the source of the high radioactivity in sample 204067, with the following result:

Equivalent uranium (percent)______________________ - ______ -__ - _ 0.010 Uranium (percent)________________________-_____ ___...____ .003 ThMss (radio-chemical) (percent). ___ ..._._ .. .- .. ................... .003Th^o (ionium) (percent equivalent).. .... - ..... ....... .009Radium (percent equivalent)_ --__ . .... .006

The analysis above indicates that Th230 and radium, both daughter products of uranium, are the principal contributors of excess radio activity. The relatively high concentrations of these elements in comparison to uranium suggest that leaching of uranium or addition of Th230 and radium has occurred in this deeply buried shale [in comparatively recent time.

The thickness and the areal distribution of radioactivity in the Bakken formation (as used by Nordquist, 1953) as determined from

______CARBONIFEROUS______________

DEVONIAN ' ~ MISSI3SIPPIAN.

Jefferson VLeatham formation formation' | of Holland, 1952_______ __________Madison toiestone

Lower black shale member

iTH


published sample descriptions and gamma-ray logs, are shown in plate 15. These maps suggest that black shale in the Bakken forma tion (as used by Nordquist, 1953) is thickest in the northwestern corner of North Dakota and that the formation is most radioactive slightly east of this area, near the northeastern corner of Montana. It seems evident that radioactivity in the Bakken formation (as used by Nordquist, 1953) varies appreciably from place to place with a definite pattern. Recognition of the pattern will help in outlining areas in which maximum concentrations of uranium in the formation may be expected.

BLACK SHALE AT THE BASE OF THE BBAZEB LIMESTONE

In parts of Utah and Idaho the basal part of the Brazer limestone of middle and late Mississippian age consists of a black phosphatic shale sequence ranging in thickness from a few inches to about 75 feet. Exposures of this zone were tested at two places in south eastern Idaho (Iocs. 21 and 22), and at one place in northwestern Utah (loc. 30). Beds of black shale at the two Idaho localities are mostly nonuraniferous, but in Rich County, Utah, a bed of shale 14 feet thick in the upper part of the sequence contains as much as 0.006 percent of uranium, and a bed of shale 8 feet thick in the lower part contains as much as 0.009 percent of uranium. The measured sections and uranium content of the black shale at the three localities are shown hi figure 53.

Black shale at the base of the Brazer limestone was examined by Duncan (1953) in Ogden Canyon, Weber County, Utah, about 45 miles southwest of the Rich County locality described above. In Ogden Canyon, Duncan reported, beds of phosphatic shale about 1 foot thick contain as much as 0.005 percent of uranium, 0.18 percent of vanadium oxide, and 17.3 percent of phosphate.

HEATH SHALE

The Heath shale of late Mississippian age crops out along the mar gins of the Little Belt and Big Snowy Mountains in central Montana, and it has been penetrated in drill holes throughout a large area in eastern Montana and western North Dakota. The formation con sists mainly of black shale, with subordinate amounts of gray lime* stone and fine- to coarse-grained sandstone. It is as much as 650 feet thick in the subsurface in the northeastern corner of Mussel- shell County, Mont., and it is as much as 400 feet thick where it is exposed on the flanks of the Little Belt and Big Snowy Mountains to the west. (See fig. 54.) The Heath is underlain by the Otter forma-


tion of late Mississippian age, which consists of green and black shale and gray limestone; it is overlain by the Amsden formation of local usage of late Mississippian and Pennsylvanian age, which consists mostly of red shale and sandstone and gray limestone and dolomite.

Sec 32, T. 13 N., R. 6 E., NEJ* sec 23, T. 12 S., R.44 E., SE3* sec 33, T. 7 S., R 40 E Rich County, Utah Bear Lake County, Idaho Caribou County, Idaho

A A A A Not sampled

- 10 -

- 20 Feet

FIGUBB 63. Uranium content of black shale at the base of the Brazer limestone, Utah and Idaho.


11<a 5C8 _.a 3

II


Outcrops of the Heath shale were examined for radioactivity at 8 places by W. J. Hail and J. K. Gill in 1951 (in Duncan, 1953), and out crops of the Heath shale were examined at 24 places by the writer in 1953. The most highly uraniferous black shale thus far found in the formation was discovered by Hail and Gill 3 miles southeast of Forest- grove, Mont., in the NWK sec. 24, T. 14 N., K. 20 E., Fergus County. At this locality, the upper 4 feet of a bed of black shale 6 feet thick near the top of the formation contains 0.006 percent of uranium. Samples of black shale from the Heath shale elsewhere in central Montana contain a maximum of 0.003 percent of uranium.

A sample of water from a seep in the upper part of the Heath shale on the north flank of the Big Snowy Mountains (loc. 66) contains 7 parts per billion of uranium.

The Heath shale is characterized locally by large deflections on gamma-ray logs of oil and gas wells. A bed 10 feet thick in the Heath shale penetrated by the Marigold Oil, Ltd.-Farnham well 1, McCone County, Mont, (well 3, table 1), may contain more than 0.01 percent of equivalent uranium; and gamma-ray logs show some parts of the formation in Musselshell County, Mont., to be almost as radio active. Not enough information is available so far to attempt to analyze the distribution of radioactivity in relation to the variations in thickness and lithology of the Heath.

LITERATURE CITED

Anderson, S. B., 1954, Stratigraphic sections of the Mississippian system in NorthDakota: N. Dak. Geol. Surv. Dept. of Inv. no. 16.

Baillie, A. D., 1953, Devonian system of the Williston Basin area: ManitobaDept. Mines and Nat. Res., Mines Br., Pub. 52-55.

Barnes, T. R., 1952, The Williston Basin a new province for oil exploration:Billings Geol. Soc. Guidebook, 3d Ann. Field Conf., Williston Basin-Black Hills,p. 97-117.

Duncan, D. C., 1953, Reconnaissance investigations for uranium in black shaledeposits of the Western States during 1951 and 1952: U. S. Geol. SurveyTEI-381, U. S. Atomic Energy Comm., Tech. Inf. Service, Oak Ridge, Tenn.

Gardner, L. S., Hendricks, T. A., Hadley, H. D., and Rogers, C. P., Jr., 1946,Stratigraphic sections of Upper Paleozoic and Mesozoic rocks in south-centralMontana: Mont. Bur. Mines and Geology Mem. no. 24.

Gott, G. B., and Hill, J. W., 1953, Radioactivity in some oil fields of southeasternKansas: U. S. Geol. Survey Bull. 988-E, p. 69-122.

Holland, F. D., Jr., 1952, Stratigraphic details of lower Mississippian rocks ofof northwestern Utah and southwestern Montana: Am. Assoc. PetroleumGeologists Bull., v. 36, no. 9, p. 1697-1735.

McConnell, R. G., 1887, Report on the geological features of a portion of theRocky Mountains, accompanied by a section measured near the 51st parallel:Geol. and Nat. History Survey of Canada, Ann. Rept. (new ser.) v. 2,p. 1D-41D.


Nieschmidt, C. L., 1953, Subsurface stratigraphy of the Heath shale and Amsden formation in central Montana: U. S. Geol. Survey Oil and Gas Inv. Chart OC50.

Nordquist, J. W., 1953, Mississippian stratigraphy of northern Montana: Billings Geol. Soc. Guidebook, 4th Ann. Field Conf., Little Rocky Mts., Mont., southwestern Saskatchewan, p. 68-82.

Perry, E. S., 1937, Natural gas in Montana: Mont. Bur. Mines and Geology, Mem. no. 3, 96 p.

Sonnenberg, F. P., Rader, M. T., and Clement, J. H., 1952, Electric and litho- logic cross-section from Norcanols Ogema [well] to Weller-Bush-Weisman [well]: Billings Geol. Soc. Guidebook, 3d Ann. Field Conf., Williston Basin- Black Hills.

Vine, J. D., 1956, Geology of the Stanford-Hobson area, Judith Basin and Fergus Counties, Mont.: U. S. Geol. Survey Bull., 1027-J, p. 405-469.

Warren, P. S., 1937, Age of the Exshaw shale in the Canadian Rockies: Am. Jour. Sci., 5th ser., v. 33, no. 198, p. 454-457.

INDEX

Bakken formation as used by Nordquist, cor relation__ 219

radioactivity, thickness and areal distri bution of. - 228,230

uranium content in drill cuttings 228 Banff formation of McConnell, correlation 219 Big Snowy Mountains..--. __ - 230-233 Brazer limestone)' black shale at base of, de

scription, radioactivity_ 230

Daniels County, Mont.. . 228

Exshaw shale of Warren, correlation.. .. 219

Forestgrove, Mont.. ... 233

Gamma-ray logs, use in present study. 214 value of sensitivity scale...._ .. 214

Geologic formations, stratigraphic relations of,table... .. __.. _ 212

Heath shate, description, radioactivity._.. 230,233

Jefferson formation, correlation. .. _ - 219

Page Little Belt Mountains. ... 230

McCone County, Mont 233 Madison limestone and equivalents, black

shale at base of, description, cor relation.. 219

uranium content observed.. __._ 228 Musselshell County, Mont. 233

Ogden Canyon, Utah 230

Phosphoria formation, excluded from presentstudy__ . 213

Koosevelt County, Mont . 228

Sappington sandstone as used by Holland,correlation_ . __ 219

Three Forks formation, correlation. __ 219 Three Forks, Mont- 228

Williams County, N. Dak.._________ 228

o

235