Radioelement and Trace-Element 

Content of the lone Formation, 

Central California

GEOLOGICAL SURVEY BULLETIN 1382-B

Prepared in cooperation with the 

Lawrence Berkeley Laboratory, 

University of California, 

Berkeley

Radioelement and Trace-Element 

Content of the lone Formation, 

Central California

By H. A. WOLLENBERG and F. C. W. DODGE

CONTRIBUTIONS TO ECONOMIC GEOLOGY

GEOLOGICAL SURVEY BULLETIN 1382-B

Prepared in cooperation with the 

Lawrence Berkeley Laboratory, 

University of California, 

Berkeley

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1973
UNITED STATES DEPARTMENT OF THE INTERIOR 

ROGERS C. B. MORTON, Secretary

GEOLOGICAL SURVEY 

V. E. McKelvey, Director

Library of Congress catalog-card No. 73-600103

For sale by the Superintendent of Documents, U. S. Government Printing Office

Washington, D. C. 20402 

Stock Number 2401-00328
CONTENTS

Page

Abstract _ ___-_ _________-_-_____ Bl

Introduction _________________________________-_- 1

Acknowledgments _________________________ 4

Analytical methods _______________________________ 4

Results and discussion ______________________ 4

Regional differences in U, Th, and K _________________ 11

Relation of radioelements to heavy minerals ______ 11

Gold content ________________________________ 13

Relation of field counting rates to Ti and Zr ________ 13 

Comparison of lone Formation and its source rocks, radioelement

contents and ratios __________________________ 14

Conclusions ________-__________________________ 15

References cited __ _____ ___ _ _____ 16

ILLUSTRATIONS

Page

FIGURE 1. Map of central California showing outcrop areas of Eocene

rocks ____________________________ B3

2. Ternary diagram relating Th, U, and K in the Eocene

rocks of various regions _ ___ 11

3. Graph showing relation between Th plus U and Ti, Zr, and

La contents in Eocene rocks 12

4. Graph showing relations between field counting rate and

Ti and Zr contents 14

TABLES

Page

TABLE 1. Summary of radioelement content of Eocene sedimentary

rocks, arithmetic mean values, and ranges B5

2. Analyses of Eocene rocks from central California 6

3. Mean and standard deviation of the mean radioelement

content of possible source rocks of the lone Formation 14

in

CONTRIBUTIONS TO ECONOMIC GEOLOGY

RADIOELEMENT AND TRACE-ELEMENT

CONTENT OF THE IONE FORMATION,

CENTRAL CALIFORNIA

By H. A. WoLLENBERG1 and F. C. W. DODGE

ABSTRACT

Radioactivity and content of uranium plus thorium in 77 samples of sandstones and clays from the Eocene lone Formation of central California correlate with abundance of titanium, zirconium, and lanthanum, suggesting 

a general correspondence between the radioelements and heavy minerals. 

There is no apparent correlation between the content of gold and radioelements. Of 77 samples of Eocene rocks, gold was detected in less than onethird; there is little probability that the element exists in exploitable amounts 

in the lone Formation.

Sandstones of the lone Formation in the lone-Buena Vista area are characterized by low potassium content as compared with their northern counterparts and with samples from the Eocene Tesla and Domengine Formations 

of the west side of the Great Valley. Sandstones from all areas sampled are 

similar in uranium and thorium contents. Processes associated with transportation and deposition rather than composition of source materials alone 

may have significantly affected radioelement concentrations in the lone.

INTRODUCTION

The lone Formation consists of interbedded anauxitic clays and 

quartz sands deposited in Eocene deltas and shallow water on the 

weathered surface of Jurassic metavolcanic and metasedimentary 

rocks of the Sierra Nevada foothills. The formation crops out in a 

narrow belt extending about 200 miles along the western margin 

of the Sierra Nevada. The presence in the lone sands of zircon and 

ilmenite in appreciable amounts suggested to Alien (1929) a predominantly granitic source, probably the Sierra Nevada batholith 

to the east, even though other granitic derivatives such as hornblende, sphene, and biotite are scarce. Alien attributed this scarcity, together with low contents of Na, K, Ca, Mg, and Fe, to

1 Lawrence Berkeley Laboratory, University of California, Berkeley.

Bl
B2 CONTRIBUTIONS TO ECONOMIC GEOLOGY

strong chemical weathering. Lignite is interbedded with sands and 

clays, particularly in the lower strata of the formation (Pask and 

Turner, 1952).

The purpose of our investigation of the lone Formation was 

twofold: (1) to investigate a possible correlation between uranium 

and thorium and heavy-mineral contents, principally zircon and 

ilmenite (characterized by abundances of Zr and Ti, respectively), 

which might in turn be indicative of gold concentrations, and (2) 

to compare regional differences in K, U, and Th with contents 

observed in granitic and pregranitic rocks of the Sierra Nevada 

(Wollenbergand Smith, 1968,1970).

Gold in minable amounts was discovered in and was recovered 

from Tertiary river channel gravels in the Sierra Nevada (Lindgren, 1911; Peterson and others, 1968; Whitney, 1880). Alien 

(1929, p. 402) noted that the gravels were deposited at least in 

part by the same streams that laid down the delta deposits of the 

lone Formation. With these aspects in mind, we sampled various 

exposures of the formation from the lone-Buena Vista area on the 

south through the Folsom-Rocklin, Lincoln, and Marysville Buttes 

areas to the north. (See fig. 1.)

In addition to samples from the lone Formation, we collected 

and analyzed samples of middle Eocene sandstones (Domengine 

and Tesla Formations) from the Nortonville and Corral Hollow 

areas of the California Coast Ranges. Alien (1941) noted the 

general similarity in mineralogy between the lone Formation and 

upper Eocene rocks of the Coast Ranges and proposed that these 

formations all had a common source, the Sierra Nevada. He observed that andalusite and anauxite, prevalent in the lone, are 

present in the Tesla and other Coast Range Eocene sandstones. 

Andalusite commonly occurs in metamorphic rocks of the Sierra 

Nevada (Dodge, 1971) but has not been reported from preTertiary rocks of the Coast Ranges. Alien's observations were confirmed by Huey (1948) in his report on the Tesla Formation and 

by Todd and Monroe (1968) in their study of the petrology of the 

Domengine Formation.

Uranium and thorium in granitic rocks are most concentrated 

in the nonmagnetic accessory minerals, monazite, zircon, allanite, 

and sphene. Of these, sphene is generally the most ubiquitous in 

granitic rocks of the Sierra Nevada batholith (Lee and Dodge, 

1964, table 2). The magnetic accessories, chromite, ilmenite, and 

magnetite, are comparatively devoid of uranium and thorium. 

Neither magnetic nor nonmagnetic accessory minerals contain 

appreciable amounts of gold in solid solution. Lindgren's (1911)
IONE FORMATION, CENTRAL CALIFORNIA

121°

B3

39° -

38° s

FIGUKK 1. Map of central California showing outcrop areas of 

Eocene rocks.

description of the heavy minerals accompanying gold in Sierran 

deposits includes radioactive (predominantly zircon) and non-
B4 CONTRIBUTIONS TO ECONOMIC GEOLOGY

radioactive accessories. Therefore, gold may or may not correlate 

with the radioactivity of the host sands of Sierran placers. Potassium, which generally contributes one-quarter to one-third of the 

observed field radioactivity, does not correlate with heavy mineral 

assemblages but rather with the abundance of K-feldspar in parent 

rocks and associated clay minerals in sand deposits.

ACKNOWLEDGMENTS

The authors thank W. P. Craven of the International Pipe and 

Ceramics Corporation for guidance in the sampling of the lone 

clay and sand pits and personnel of the Calaveras Cement Company for providing samples and descriptions of the Gerberding 

drill core. The work was done partly under the auspices of the U.S. 

Atomic Energy Commission.

ANALYTICAL METHODS

At about half of the sampled locations, field gamma radioactivity 

was measured with a sensitive portable scintillation counter having 

a 3- by 3-inch Nal(Tl) detector. Thus field radioactivity could be 

directly compared with trace-element concentrations. Samples of 

1.5 to 2 kg (kilograms) were collected in polyethylene bags. Moist 

samples were dried, then all were packaged in tight polyethylene 

containers, holding 0.8 to 1 kg, for gamma-ray spectrometry for 

K, U, and Th at the gamma-counting facility at Lawrence Berkeley Laboratory. Counting, pulse-height analysis, and data reduction 

have been described by Wollenberg, Smith, and Bailey (1967). 

After gamma counting, splits of the same materials were analyzed 

at the U.S. Geological Survey laboratories for gold by atomic absorption (Thompson and others, 1968) and for several other elements by semiquantitative spectrometric methods using techniques 

described by Grimes and Marranzino (1968). Analytical data, sample locations, and sample descriptions are given in table 2.

RESULTS AND DISCUSSION

Radioelement contents of Eocene rocks are summarized by lithologic type and geographic location in table 1. Data on the lone 

Formation are arranged in groups according to areas, from north 

to south. The lone sandstones sampled in the lone-Buena Vista 

area are characterized by a low potassium content (average 0.25 

percent) as compared with sandstone from other areas.

Pask and Turner (1952) recognized an upper predominantly 

sandy facies and a lower predominantly clayey facies in the lone 

Formation in the Buena Vista area. Closely spaced samples were
IONE FORMATION, CENTRAL CALIFORNIA B5

TABLE 1. Summary of radioelement contents of Eocene sedimentary 

rocks, arithmetic mean values, and ranges

[Samples are from rocks of the lone Formation except in the Nortonville-Corral Hollow area 

where they are from rocks of the Tesla and Domengine Formations. Ss=dominantly sandstones and conglomerates; Cl = clays and lignites. U and Th content in parts per million; 

K content in percent; range given in parentheses beneath mean values]

Location

lone roadcut _ .. _ . _ ___._.

Nortonville-Corrall Hollow

Sample 

type

Ss

Ss

Cl 

Ss

Ss

Cl 

Ss

Cl

Ss

Number 

of U 

samples

2 2.25

(2.06-2.45) 

1 1.50

6 4.87 

(1.50-7.98) 

4 2.52

(2.40-3.78) 

19 4.87

(0.59-17.6) 

7 1.75 

(1.39-3.09) 

16 8.16

(1.31-38.5) 

13 4.90

(1.85-62.2) 

5 1.51

(1.23-2.21)

Th

7.30

(6.25-8.35) 

4.06

12.8 

(4.00-17.7) 

8.25

(2.81-12.4) 

18.5

(1.62-73.4) 

7.08 

(3.19-10.1) 

35.9

(7.13-227) 

8.40

(3.72-14.8) 

5.66

(4.56-9.01)

K

2.38

(1.93-2.82) 

0.43

1.24 

(0.42-1.68) 

1.30

(0.59-2.21) 

0.24

(0.07-1.09) 

0.52 

«0.01-2.00) 

0.14

«0.01-0.60) 

0.43

(0.04-1.78) 

1.37

(0.21-2.77)

Th/U

3.2

2.7

3.0 

3.3

4.0

4.4 

4.6

2.1

3.7

taken from a roadcut in the upper sandstones near lone and from 

drill core from the clays of the lower lone Formation near Buena 

Vista. The sandstones of the roadcut (samples 14-3' to 14-49') 

showed a broad range of U and Th contents, roughly following 

variations in Zr, Ti, and La. This suggests a correlation of radioelements with zircon, ilmenite or sphene, and perhaps monazite. 

It is interesting to note that generally the highest U contents were 

not associated with lignitic sandstones, but rather with the gray 

sandstones (samples 14-30' through 14-49') indicative, by their 

dark color and their generally high Zr and Ti contents, of high 

heavy-mineral contents. Generally, lone sandstones and clayey 

sandstones have a broader range in Th and Th/U ratio than do the 

predominantly clayey sediments, although average U content is 

similar for the two rock types.

Clays of the lower lone Formation in the Valley Springs area 

near Buena Vista are typified by the samples from the Gerberding 

borehole (samples G-22' to G-238'). The hole was drilled 254 feet 

and bottomed in the strongly weathered surface of Jurassic metamorphic rocks at the base of the lone Formation. Highest uranium 

contents in the core were in an interval of gray lignitic sand 

(sample G-162') where U predominates over Th by a factor of 

5.5. As this is the only specific indication in our samplings of strong 

preferential concentration of U by carbonaceous material, this 

lignitic sandstone has been excluded from the averages of table 1. 

Other lignitic samples from the cores and from surface exposures
TABLE 2. Analyses of Eocene rocks from cen

[General area of sample locality designated by the following letters: M=Marysville Buttes, I 

coln area, N = Nortonville-Corral Hollow area; range and township lines are referred to M

clay or sand pit, mill c = mill concentrate, drill c = drill core or cutting or cuttings, n o

stone, cgl = conglomerate, sh=shale, yl = ye'low, brn = brown. Semiquantitative spectrogra

metric midpoints of ranges whose boundaries are 1.2, 0.83, 0.56, 0.38, and 0.18 (or multiples 

0.2, and 0.15 (or appropriate multiples). Other analytical results are reported to the nea

E. L. Mosier, and J. M. Motooka. Chemical analyses (atomic absorption) by W. L. Campb

Gamma-ray analyses by A R. Smith and H. A. Wollenberg. Undetected elements present in 

spective detectibility levels (ppm): Ag (0.5), As (200), Bi (10), Cd (20), Sb (100), Sn (

Semiquantitative spectrographic analys

Percent

Sample Fe Mg Ca Ti B Ba Be Co

lone Formation

1 ______ __ .

2 __________ .

3 __ _____ _.

5 _____ . __ .

6 ________ _.

8 _ ____ - .

9

10 - - -- ...

11 __________ .

12 ___ _____ .

13 - _________ .

14- 3' .... _____ .

14- 6' ____ ___ .

14- 9' . . __ __ .

14-12' _____ . ...

14-15' __ ........ .

14-18' ________ ..

14-21' .... _____ .

14-24' . ____ __ ....

14-27' _________ .

14-30' _____ _.

14-33' _________ .

14-39' __ ___ __ .

14-42' .. .. _____ .

14-49' __ . ......

15

16 - .- _ --

17 __ ._. 

5

2

.5

.5

15

7

5

1.5

1.5

2

3

1.5

2

3

3

5

5

3

.7

1

.3

.3

1

3

3

2

1

.7

3

1.5

1

1 

.3 

.03 

.05 

.05 

.07 

.3 

.3 

.05 

.1 

.5 

.05 

.05 

.03 

.02 

.02 

.03 

.03 

.02 

.03 

.03 

.03 

.05 

.07 

.05 

.1 

.05 

.07 

.05 

.5 

.3 

.3

2 

.5

<.05 

<.05 

<.05 

<.05 

<.05 

<.05 

<.05 

<.05 

<.05 

.07 

<.05 

<.05 

<.05 

<.05 

<.05 

<.05 

<.05 

<.05 

<.05 

<.05 

<.05 

<.05 

<.05 

<.05 

<.05 

<.05 

<.05 

.1 

.05 

.05

0.5 

.2

1 

.5

.7 

1 

1 

.1

1 

1

1 

.5 

.3 

1 

.7 

.5 

.5 

.5 

.5 

.5

1

1 

1

1 

1

70

50 

10 

30 

20 

30 

50

50 

70 

70 

50 

20 

10 

30 

20 

30 

10 

20 

10 

20 

70 

300 

100 

70 

50 

50 

70 

150 

70 

100

1,500 1 

1,000 1 

100 <1 

70 <1 

50 <1 

100 <1 

300 <1 

300 <1 

100 <1 

150 <1 

150 <1 

300 <1 

100 <1 

100 <1 

30 <1 

70 <1 

500 <1 

50 <1 

70 <1 

SO <1 

70 <1 

30 <1 

100 <1 

150 <1 

100 <1 

200 <1 

150 <1 

150 <1 

150 <1 

150 <1 

700 <1 

1,500 1

10 

10 

<5 

<5 

<5 

<5 

<5 

<5 

<5 

<5 

<5 

<5 

<5 

<5 

<5 

<5 

<5 

<5 

<5 

<5 

<5 

<5 

<5 

<5

<5

<5 

<5 

<5 

5 

<5 

<5
TABLE 2. Analyses of Eocene rocks from central C

Sample

Semiquantitative spectrographic 

analyses Continued

Parts per

Pb Sc Sr

million

V Y Zr

Chemical 

analysis 

(ppm)

Au

Gamma-ray analyses

Ppm Percent

Th

lone Formation1 __ _ ..

2 ________

5

6 _ _ _____

9 ________

10 ________

11 _..__.

12 ________

13 ._._.___

14- 3' _______

14- 6' _______

14- 9' _______

14-12' _______

14-15' _______

14-18' _______

14-21' _______

14-24' _______

14-27' _______

14-30' _____

U

OO'

14-39' _______

14 42'

14-45' _______

14-49' _______

15 ________

16 ________

17 _ __ ____

10

10

30

<10

<10

<10

<10

<10

10

70

10

50

Oft

10

15

i <10

 <v.

15 

5 

5 

10 

20 

5 

15 

15 

5 

20 

50 

20 

15 

5 

5 

10 

10 

10 

7 

5 

5 

5 

15 

50 

20 

20 

20 

15 

15 

50 

15 

20

300 

200 

<100 

<100 

<100 

<100 

100 

100 

<100 

<100 

<100 

<100 

<100 

<100 

<100 

<100 

<100 

<100 

<100 

<100 

<100 

<100 

<100 

<100 

<100 

<100 

<100 

<100 

<100 

<100 

<100 

100

150 

30 

50 

100 

150 

70 

200 

150 

50 

150 

200 

200 

150 

70 

50 

100 

70 

100 

30 

30 

50 

30 

200 

500 

200 

150 

150 

200 

150 

300 

200 

300

20 200 

10 150 

20 >1,000 

20 300 

50 >1,000 

<10 >1,000 

10 200 

10 200 

<10 70 

15 >1.000 

15 200 

30 >1,000 

15 >1,000 

<10 100 

<10 100 

<10 1,000 

15 500 

15 200 

10 200 

10 200 

<10 100 

<10 200 

30 >1,000 

100 >1,000 

70 >1.000 

100 1,000 

100 >1,000 

50 1,000 

20 300 

10 200 

10 200 

30 200

0.03 

.02 

<.02 

<.02 

<.02 

.02 

<.02 

<.02 

.04 

.03 

.02 

.03 

.03 

<.02 

<.02 

<.02 

<.02 

<.02 

.02 

<.02 

<.02 

<.02 

.04 

<.02 

<.02 

.04 

.07 

.07 

.04 

.03 

.03 

.03

8.35 

6.25 

15.7 

10.7 

26.8 

5.42 

8.39 

10.1 

1.86 

12.7 

7.10 

73.4 

23.3 

13.4 

1.6 

25.7 

21.2 

14.4 

7.13 

9.58 

8.83 

8.01 

66.5 

227 

70.6 

22.7 

22.1 

16.5 

29.5 

8.89 

5.59 

8.89

U K

 Continued

2.45 

2.06 

7.06 

1.75 

5.10 

1.62 

2.22 

1.70 

0.35 

3.24 

1.62 

17.6 

7.60 

2.47 

2.16 

3.70 

6.19 

2.86 

1.31 

1.92 

1.87 

1.55 

9.92 

38.5 

15.3 

19.7 

9.81 

6.20 

7.17 

3.09 

1.54 

1.76

1.93 

2.82 

.07 

.16 

.10 

.25 

.90 

1.01 

.07 

.21 

.46 

.36 

.21 

.09 

.08 

.13 

.13 

.08 

.07 

.09 

.07 

.11 

.34

!23 

.60 

.19 

.24 

.19 

.30 

1.09 

2.00
TABLE 2. Analyses of Eocene rocks from central C

Semiquantitative spectrographic analys

Percent

Sample

18 ________ __ .

19 _ . . __ _ _. ..

20 ___. ______ ___.

21 _________ .

22 ___ _________ .

23 ___________ .

24 ______ _ ____ .

25 __ _ __ _____ .

26 __________ .

27 . _ ____ ___ .

29 ___________

30 . __ _______ .

31 ____________ .

32 _________ ._

33 ______ ___ .

34 ___ __ __ __ .

35 ______ _

36 . . _________ .

37 ______ __

38 _______

39 _____ _____ .

40 _______ _ _,_.

41 ____________ .

42 - __ __ ____ .

43 ___________ .

C-6

G-22' _____ __ .

G-36' ______ __

G-51' _________ .

G-79' . ___ . __.

G-88' ______ ._

G-106' ____ _ .

G-127' _________ .

G-147' ____ _____

G-162' _________ .

G-164' ____ __ .

G-195' ____ _____

G-213' __ _

G-223' __ __ __ .

G-238' ____________

Fe

5

7

5

7

7

5

7

5

3

3

5

. . 1

1.5

0.5

1.5

1.5

.3

1

.1

5

.15

.3

>20

10

5

.5

15

1.5

7

.6

5

5

7

10

1.5

6

7

15

10

10

Mg

1.5 

.7 

1 

3 

.2 

1 

.5 

.7 

.5 

.7 

.05 

.05 

.02 

0.2 

.5 

.15 

.2 

.02 

.07 

.05 

.2 

.03 

.07 

.5 

.3 

.1 

.7 

.5 

.5 

.2 

.15 

.7 

.7 

.7 

.5 

.7 

.5 

.5 

.7 

.5

Ca

1.5 

.1 

10 

3 

.1 

.5 

.05 

.05 

.07 

.2 

.1 

<.05 

<.05 

<.05 

<.05 

<.05 

.05 

<.05 

1.5 

<.05 

<.05 

<.05 

<.05 

1 

.15 

.05 

.15 

.07 

.05 

.2 

.05 

.15 

.2 

.2 

.3 

.3 

.15 

.15 

.2 

.1

Ti

0.7 

.5 

3 

1 

.7 

.5 

.7 

.7 

1 

.5 

.5 

.7 

.3 

0.5 

.7 

.3 

.7 

.7 

.3

1

.7 

.3 

1 

1 

.7 

.7 

1 

.3 

1 

1 

1 

1 

1

1

.7 

1 

.7

B

lone

10 

20 

15 

10 

20 

20 

70 

100 

70 

30 

20 

15 

30 

100 

70 

20 

30 

20 

50 

300 

50 

70 

50 

500 

100 

20 

30 

20 

30 

15 

30 

30 

70 

70 

30 

70 

70 

70 

70 

100

Ba Be Co

Formation Continued

1,500 

1,500 

2,000 

500 

150 

700 

500 

3,000 

500 

700 

150 

150 

70 

700 

700 

300 

500 

300 

2,000 

300 

100 

150 

70 

300 

500 

30 

100 

300 

150 

30 

70 

200 

300 

200 

200 

200 

200 

300 

300 

1,500

1

1 

1

1

2 

10

1 

1

1

20 

10 

5 

30 

7 

10 

10 

15 

5 

10 

5 

<5 

<5 

<5 

10 

<5 

<5 

<5 

10 

<5 

<5 

<5 

10 

<5 

<5 

<5 

20 

30 

<5 

5 

7 

70 

15 

5 

150 

10 

5 

30 

30 

<5
TABLE 2. Analyses of Eocene rocks from central 

Semiquantitative spectrographic 

analyses -Continued

Parts per

Pb Sc Sr

million

V Y Zr

Chemical 

anal-

(ppm)

Au

Gamma-ray analyses

Ppm Percent

Tb

lone Formation18 _______ .

19 __ ____ .

20 ________ .

21 . _______ .

22 ________ .

23 ________ .

24 ________ .

25 .. ___ . __ .

26 .. ___ . __ .

27 ______ ..

29 ____ __ .

30 . ___

31 .. ___ . __ .

32 . __ __ .

33 ___

34 ___ ..

35 __ . ...

36 _ ._ ______

37 _ _ .. ._

38 ___

39 . ________

40 .. _________

41 .. .. _____

42 - _________

43 _. __ .. ..

C-6 __ _____

G-22' ________

G-36' _ ______

G-51' ___ ..

G-79' ________

G-88'

G-106' ______

G-127' _ ___

G-147' _______

G-162' __ ..

G-164' __ .

G-195' _______

G-213' ______

G-223' _______

G-238' _______

10

<C10

. _ . <io

<10

<C10

<10

10

10

10

... <10

<10

<10

<10

<C10

--. . <10

<10

<C10

- . 15

<10

20

- ... 15

. -_ 70

__ 15

20

<C10

- __ 15

 _. 20

- ... 30

<C10

15

<10

<10

<10

<10

__ 10

10

... . <10

<C10

..... <10

15

15

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in sandstones and clays show Th/U ratios of the order of those in 

the nonlignitic sandstones and clays, but the mean Th/U ratio of 

clays and lignites is somewhat lower than that of sandstones. From 

a regional standpoint, clays of the lone-Buena Vista area contain 

appreciably less potassium than clays at Lincoln.

REGIONAL DIFFERENCES IN U, Th, AND K

The relations between contents of U, Th, and K in different 

regions are illustrated in the ternary diagram of radioelement fraction (normalized to U(ppm)+Th(ppm)+K(percent) 100), figure 2. The generally low-K field of the samples from the loneEXPLANATION

Northern (Marysville Buttes, Lincoln, 

Rocklin-Folsom areas) exposures of 

the lone Formation

lone-Buena Vista area

Nortonvi lie-Corral 

Hollow area

FIGURE 2. Relation of radioelement contents of Th, U, and K in Eocene rocks, 

normalized to U(ppm)+Th(ppm)+K(percent) =100.

Buena Vista area covers a broad range of Th/U, as does the relatively higher K field of the Nortonville-Corral Hollow samples.

RELATION OF RADIOELEMENTS TO HEAVY MINERALS

The apparent correlation between radioelements and heavy minerals on a formation-wide basis was tested by plotting Th+U
B12 CONTRIBUTIONS TO ECONOMIC GEOLOGY

against semiquantitative spectrographic values of Zr, Ti, and La 

(fig. 3). Absolute values of Zr greater than 1,000 ppm (parts per 

million) and Ti greater than 1 percent are not reported; nevertheless, the plot shows generally positive trends and indicates, in 

turn, the general correspondence of Th and U and heavy minerals. The relatively high concentration of La (^=70 ppm) in 

highly radioactive gray sandstones (samples 14-30' to 14-49', table 2) suggests the presence of rare-earth minerals, perhaps allan0.1

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1000

100

100

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U+Th CONTENT, IN PARTS PER MILLION

FIGURE 3. Relation between Th plus U and Ti, Zr, and La contents in

Eocene rocks.
ZONE FORMATION, CENTRAL CALIFORNIA B13

ite and (or) monazite, although these minerals were not reported 

by Alien (1929), and Lindgren (1911) noted the conspicuous absence of monazite in the Tertiary gravels (also see Lee and Dodge, 

1964). The positive correlation between Th and U and heavymineral concentrations in present-day Gulf and Atlantic coast 

beach sands was described by Mahdavi (1964).

In some localities, sandstones with high Th and U contents have 

relatively high Mn contents, as shown in table 2. With one marked 

exception, the lignitic sandstone near Buena Vista with abundant 

U (sample G-162'), highly radioactive sandstones are low in Ni 

and Mg, components most likely derived from ultramafic source 

rocks; the highly radioactive sandstones are generally high in Cr, 

however. Quartz-pebble conglomerates near the base of the lone 

Formation have the lowest U and Th contents, attesting to the 

abundance of quartz.

GOLD CONTENT

There is no apparent correlation between Th, U, or whole-rock 

radioactivity (counts per minute per gram of sample) and gold 

content. Of the 77 analyzed samples, 24 had values exceeding the 

atomic-absorption analyses detection limit of 0.02 ppm Au. The 

highest Au content measured in the Eocene sandstones, 0.21 ppm, 

was in a sample of Tesla Formation from Corral Hollow; radioelement contents were 2.21 ppm U and 9.01 ppm Th. This sample 

contained intermediate amounts of Ti and Zr (0.5 percent and 

100 ppm, respectively). Gold was below the detection limit in the 

richest Th-U Zr-Ti samples of dark sandstones from the roadcut 

near lone (samples 14-30' and 14-36'). A sample of brownish 

sandstone from the Lincoln area (No. 21) contained 0.10 ppm Au, 

greater than 1,000 ppm Zr, and 1 percent Ti. However, radioelement contents of the sample were relatively low: 1.50 ppm U and 

4.06 ppm Th. There appears to be little or no correlation between 

gold and heavy-mineral contents in the Eocene sandstones.

RELATION OF FIELD COUNTING RATES TO Ti AND Zr

From the plot of radioelements relative to Ti and Zr in figure 3, 

one may surmise that there are similar relations between field 

counting rates and Ti and Zr, representatives of heavy-mineral 

concentrations. The plot shown in figure 4 indicates that the 

gamma-ray counting rates measured on the outcrop vary roughly 

with zircon and ilmenite contents in the sands (field counting 

rates were measured at only about one-half of the sample 

localities).
B14 CONTRIBUTIONS TO ECONOMIC GEOLOGY

z

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1600

FIGURE 4. Relations between field counting rate and Ti and Zr contents.

COMPARISON OF IONE FORMATION AND ITS SOURCE ROCKS, 

RADIOELEMENT CONTENTS AND RATIOS

Radioelement contents and Th/U ratios of the lone Formation 

sandstones and clays, summarized in table 1, can be compared with 

mean radioelement contents of possible source rocks of the lone 

(table 3). Units sampled previously, which are probably repreTABLE 3. Mean and standard deviation of the mean radioelement content 

of possible source rocks of the lone Formation

u

(ppm)

Th 

(ppm)

K

(percent) Th/U

Unit sampled

Stand- Standard ard 

devia- deviaMean tion Mean tion

Stand- Standard ard 

devia- deviaMean tion Mean tion

Granitic rocks of the YosemiteSan Joaquin region (from

Wollenberg and Smith, 1968) . 3.95 2.33 12.5 

Rocklin pluton (Wollenberg,

unpub. data) and Bucks

Granodiorite of Whitfleld

and others (1969, p. 267-277). 2.2 .8 4.0 

Prebatholithic rocks of the

central Sierra Nevada (from

Wollenberg and Smith, 1970).. 2.31 1.05 5.71

8.0

1.6

2.37

1.34

1.01 3.7

2.0

.55 2.7

1.4

1.1

1.0

Overall values __..___ 2.8 __.- 5.7 1.7 2.8
IONE FORMATION, CENTRAL CALIFORNIA B15

sentative of the Tone's source materials, are granitic rocks of the 

Yosemite-San Joaquin region, the Rocklin and Bucks plutons, and 

pregranitic Paleozoic and Mesozoic rocks of the western slope of 

the Sierra Nevada. Although the Yosemite-San Joaquin granitic 

rocks are well to the south of the lone-Buena Vista area, analyses 

of various samples of granitic rocks collected between Yosemite 

and Lake Tahoe indicate similar Th, U, and K contents. The Th and 

U contents of the sandstones and clays in the lone-Buena Vista 

area are similar to, or somewhat higher than, those in granitic 

rocks of the Yosemite-San Joaquin region. Radioelement contents 

of the northerly exposures of lone sandstones are more nearly 

like those of the pregranitic rocks and the Bucks and Rocklin plutons. However, clays at Lincoln are similar in K, U, and Th contents to the more radioactive granitic rocks. These comparisons 

suggest that the Eocene sandstones and clays in the lone-Buena 

Vista area were derived from a region of predominantly granitic 

rocks. The relatively high Th and U contents of the Lincoln clays 

as compared with considerably lower values of some of the northerly sandstones make it difficult to associate possible source rocks to 

the sediments of the northern areas. Low K contents of the samples from the lone-Buena Vista area relative to the more potassic 

northerly samples suggest that processes associated with transport 

and deposition, rather than composition of source materials alone, 

may have played a key role in the distribution of radioelements in 

the Eocene sedimentary rocks.

The overall mean Th/U ratio in the Eocene sandstones and clays 

is 3.65, similar to the ratios in Sierran rocks listed in table 3. However, Th/U ratios are different in the two litholoic categories used 

in table 1, being higher in sandstones and conglomerates (mean 

4.05) than in clays and lignites (mean 2.93). This suggests some 

t'ractionation of U and Th, most likely after deposition of the sediments, as U, more mobile as the uranyl ion than Th, would associate readily with the clays, especially in the reducing environment 

afforded by lignitic material.

CONCLUSIONS

There is little probability that gold exists in exploitable concentrations in the lone Formation, nor is there any apparent correlation between radioelements and gold content. Gold content of 

samples of the formation was found not to exceed 0.10 ppm, and 

generally was less than 0.02 ppm. Apparently most of the available 

gold carried down by streams was deposited in the river channels, 

and only small amounts reached the depositional basin of the lone 

Formation.
B16 CONTRIBUTIONS TO ECONOMIC GEOLOGY

The formation in the vicinity of lone-Buena Vista is characterized by relatively high Th/U ratios and scarce K. High radioactivity is associated with dark streaks in sandy members where 

spectrographic analyses indicate an abundance of Ti, Zr, and La. 

North of the lone-Buena Vista area the formation contains generally lower Th and U and considerably more K, as do samples of 

the Tesla and Domengine Formations from the west side of the 

Great Valley.

High radioactivity and Th/U ratios in the formation near lone 

and Buena Vista suggest a predominantly granitic source. Lower 

radioelement contents and ratios in the more northerly exposures 

may indicate that their source region was underlain mainly by prebatholithic rocks, but compositions most likely have been modified 

by processes of transport and deposition.

REFERENCES CITED

Alien, V. T., 1929, The lone Formation of California: California Univ. Pubs., 

Bull. Dept. Geol. Sci., v. 18, p. 347-448.

 1941, Eocene anauxitic clays and sands in the Coast Range of California: Geol. Soc. America Bull., v. 52, p. 271-294.

Dodge, F. C. W., 1971, Al2Si05 minerals in rocks of the Sierra Nevada and 

Inyo Mountains, California: Am. Mineralogist, v. 56, p. 1443-1451.

Grimes, D. J., and Marranzino, A. P., 1968, Direct-current arc and alternating-current spark emission spectrographic field methods for semiquantitative analysis of geologic materials: U.S. Geol. Survey Circ. 591, 

6 p.

Huey, A. A., 1948, Geology of the Tesla quadrangle, California: California 

Div. Mines Bull. 140, 75 p.

Lee, D. E., and Dodge, F. C. W., 1964, Accessory minerals in some granitic 

rocks in California and Nevada as a function of calcium content: Am. 

Mineralogist, v. 49, p. 1660-1669.

Lindgren, Waldemar, 1911, The Tertiary gravels of the Sierra Nevada of 

California: U.S. Geol. Survey Prof. Paper 73, 226 p.

Mahdavi, Azizeh, 1964, The thorium, uranium, and potassium contents of 

Atlantic and Gulf coast beach sands, in The natural radiation environment: Chicago, 111., Univ. Chicago Press (for William Marsh Rice 

Univ.), p. 87-114.

Pask, J. A., and Turner, M. D., 1952, Geology and ceramic properties of the 

lone Formation, Buena Vista area, Amador County, California: California Div. Mines Spec. Rept. 19, 39 p.

Peterson, D. W., Yeend, W. E., Oliver, H. W., and Mattick, R. E., 1968, 

Tertiary gold-bearing channel gravel in northern Nevada County, 

California: U.S. Geol. Survey Circ. 566, 22 p.

Thompson, C. E., Nakagawa, H. M., and VanSickle, G. H., 1968, Rapid 

analysis for gold in geologic materials, in Geological Survey research 

1968: U.S. Geol. Survey Prof. Paper 600-B, p. B130-B132.

Todd, T. W., and Monroe, W. A., 1968, Petrology of Domengine Formation 

(Eocene), at Potrero Hills and Rio Vista, California: Jour. Sed. Petrology, v. 38, p. 1024-1039.
IONE FORMATION, CENTRAL CALIFORNIA B17

Whitfield, J. M., Rogers, J. J. W., and Adams, J. A. S., 1959, The relationship 

between the petrology and the thorium and uranium contents of some 

granitic rocks: Geochim. et Cosmochim. Acta, v. 17, p. 248-271.

Whitney, J. D., 1880, The auriferous gravels of the Sierra Nevada of California: Harvard Coll. Mus. Comp. Zoology Mem. v. 6, no. 1, 569 p.

Wollenberg, H. A., and Smith, A. R., 1968, Radiogeologic studies in the 

central part of the Sierra Nevada batholith, California: Jour. Geophys. 

Research, v. 73, no. 4, p. 1481-1495.

 1970, Radiogenic heat production in prebatholithic rocks of the central 

Sierra Nevada: Jour. Geophys. Research, v. 75, p. 431-438.

Wollenberg, H. A., Smith, A. R., and Bailey, E. H., 1967, Radioactivity of 

upper Mesozoic graywackes in the northern Coast Ranges, California: 

Jour. Geophys. Research, v. 73, p. 4139-4150.

* U.S. GOVERNMENT PRINTING OFFICE: 1973 515 657/43