Distribution of Thorium 

Uranium, and Potassium in 

Igneous Rocks of the Boulder 

Batholith Region, Montana, and 

Its Bearing on Radiogenic Heat 

Production and Heat Flow

GEOLOGICAL SURVEY PROFESSIONAL PAPER 614-E

Distribution of Thorium 

Uranium, and Potassium in 

Igneous Rocks of the Boulder 

Batholith Region, Montana, and 

Its Bearing on Radiogenic Heat 

Production and Heat Flow

By ROBERT I. TILLING and DAVID GOTTFRIED

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

GEOLOGICAL SURVEY PROFESSIONAL PAPER 614-E

A study of the relationship between 

content of heat-producing elements

J 1 O

and host-rock chemistry and heat flow

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1969
UNITED STATES DEPARTMENT OF THE INTERIOR 

WALTER J. HICKEL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director

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

Washington, D.C. 20402 - Price 40 cents (paper cover)
CONTENTS

Page 

Abstract ________________________________________ El

Introduction. ____ ______ ___ _ 1

Acknowledgments __ 2 

Geologic setting... _____ ___ ___ 2

Distribution of thorium, uranium, and potassium in 

igneous rocks of the Boulder batholith region _ _ 6 

Prebatholith volcanic rocks______ _ 6

Batholith rocks________ _______ ________ 6

Postbatholith volcanic rocks________ _______ 6

Para 

Distribution of thorium Continued

Summary and comparison of thorium, uranium, and 

potassium abundance data____________________ E10

Nature of variation in thorium and uranium content.___ II 

Comparison of thorium and uranium distribution between 

contrasting magma series.__________________ 12

Radiogenic heat production and heat flow-________ 17

References.. ______________________________ 19

ILLUSTRATIONS

Par* 

FIGUBE 1. Sketch map showing the areal distribution of igneous rocks in the Boulder batholith region_______________ F3

2. Generalized geolgic map of the Boulder batholith and vicinity________________________________ ____ 4

3-5. Graphs showing relations of thorium and uranium contents and SiO2, K2O, and CaO/CN^O+KcO) in 

3. Prebatholith volcanic rocks of the Boulder batholith region____________________________________ 7

4. Rocks of the Boulder batholith-___________________________________________________________ 8

5. Postbatholith volcanic rocks of the Boulder batholith region_____________-_-_____ _________ 9

6. Thorium and uranium distribution curves of selected igneous suites_____________----__-____---_---_--__- 14

7. Graphs showing a comparison of thorium and uranium distribution patterns of selected granodiorites and

adamellites_-__________________________________________________________ 16

TABLES

TABLE 1. Intel-laboratory comparison of results of analyses for thorium and uranium on four standard rock samples. __

2. Summary of thorium, uranium, and potassium values and weighted average values for rocks of the Boulder 

batholith _ _ _________ _ _____ _ ______ _ _______ _ ____________ ----- ___ --

3. Summary of thorium, uranium, and potassium values for prebatholith and postbatholith volcanic rocks compared with weighted average values for the Boulder batholith________________ ___ _____

4. Comparison of the thorium and uranium distribution between hydrothermaUy altered Butte Quartz Monzonite 

samples and their fresh, unaltered counterparts __ ________ __ _____________________-_----_--_----

5. Lime-alkali indices and median Th/U ratios of selected suites of igneous rocks____ ________-__-_---_-----_-

6. Radiogenic heat production in igneous rocks of the Boulder batholith and in some other crystalline materials. 

7-12. Distribution of thorium, uranium, and potassium in 

7. Prebatholith volcanic rocks of the Boulder batholith region.. ___ 

8. Rocks of the Boulder batholith ___ _ __ ___ __ _______________ __ _ -- 

9. Mafic inclusions in some rocks of the Boulder batholith.- _ _______________ __________________

10. Postbatholith Lowland Creek Volcanics (early Eocene)

F-2

10

11

12

13

17

24

25

27

27

11. Postbatholith igneous rocks of probable early Tertiary age in the Boulder batholith region. ______ 27

12. Post-Lowland Creek volcanic rocks (Miocene or Pliocene) _ _____________ _ ________________ 28

13. Distribution of thorium and uranium in the Butte Quartz Monzonite from underground workings in the Butte

district, Montana __ ____________________________________________________-___---_--------_-_-- 28

14. Distribution of thorium, uranium, and potassium in Butte Quartz Monzonite samples from a drill hole for

which heat flow has been measured______________________________________-__-__---_-_--_-__----- 29

15. Distribution of thorium, uranium, and potassium in a single stock of Woodson Mountain Granodiorite, Southern California batholith _______ _______________________________ _ 29

in

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

DISTRIBUTION OF THORIUM, URANIUM, AND POTASSIUM IN IGNEOUS ROCKS OF THE 

BOULDER BATHOLITH REGION, MONTANA, AND ITS BEARING ON RADIOGENIC HE^T

PRODUCTION AND HEAT FLOW

By ROBERT I. TILLING and DAVID GOTTPBIED

ABSTRACT

Thorium and uranium contents in about 150 samples of igneous 

rocks from the Boulder batholith region generally increase with 

increasing SiC>2 content and decreasing CaO/(Na2O+K8O) ratio 

of their host rocks. Prebatholith volcanic rocks (the Upper 

Cretaceous Elkhorn Mountains Yolcanics and its correlatives) 

vary in thorium, uranium, and potassium contents from one outcrop area to another: two areas contain rocks with average values 

of 2.4-2.6 percent K, 6.0-6.6 ppm (parts per million) Th, 2.1-2.9 

ppm U, and Th/U ratios between 2.4 and 3.2; a third area contains 

rocks with average values of 3.5 percent K, 16.6 ppm Th, 3.7 

ppm U, and a Th/U ratio of 4.2. The older (and more mafic) 

rocks of the composite Boulder batholith (also Late Cretaceous) 

have an average content of 6.2-11.0 ppm Th and 1.5-3.4 

ppm U, whereas the younger (and more felsic) rocks have an 

average content of 15.7-36.3 ppm Th and 4.0-9.2 ppm U. The 

average radioelement content of the batholith, weighted according to areal abundance of constituent rocks, is 3.3 percent 

K, 15.4 ppm Th, and 3.9 ppm U. Average Th/U ratios of the 

batholith samples range from 4.0 to 5.8 and have no apparent 

correlation with rock composition or position in the intrusive 

sequence. Postbatholith volcanic rocks (the Lowland Creek 

Volcanics of early Eocene age and post-Lowland Creek rocks of 

Pliocene or Miocene age) have thorium, uranium, and potassium 

contents comparable with those in some of the younger batholith 

rocks.

Comparison of the Boulder batholith with selected igneous 

suites representative of diverse magmatic provinces shows that 

its thorium and uranium distribution is typical of that for calcalkalic suites. The thorium and uranium distribution pattern of 

any comagmatic igneous suite can be grossly correlated with its 

lime-alkali (Peacock) index, which in turn reflects differences in 

tectonic setting and (or) magma provinces. Calculated from 

average thorium, uranium, and potassium contents (using 

Birch's heat-generation values), the total radiogenic production 

of the calc-alkalic Boulder batholith (weighted according to rock 

abundance) is 6.8 microcalories per gram per year, as opposed 

to a similarly computed value of 2.7 microcalories per gram per 

year for the calcic Southern California batholith.

Available heat-flow measurements from a drill hole and underground workings in the Butte Quartz Monzonite near Butte are 

about 2.2 microcalories per square centimeter per second. 

Calculations demonstrate that the observed heat flow can be 

fully attributed to radiogenic heat produced in a column of 

surface rocks 25-35 kilometers thick (depending on the average 

thorium, uranium, and potassium contents used in the calculation), even though limited seismic data indicate that the crust 

in the Boulder batholith region is about 45 kilometers thick. 

The apparent discrepancy between radiogenic heat production 

and heat flow may be resolved by postulating that the content

of heat-producing elements in the crust decreases with depth, 

which has also been suggested by other investigators as part'il 

explanation for analogous discrepancies between heat flow and 

radiogenic heat in the Sierra Nevada batholith.

INTRODUCTION

Data on the distribution of heat-producing elemerts 

(thorium, uranium, and potassium) in igneous rocks are 

fundamental to interpretation of petrologic, isotop; °., 

and geologic evidence pertinent to many problems of 

magma generation and differentiation, radiogenic heat 

production and heat flow, and, in the broadest sense, 

evolution of the earth's crust. It is now generally f ocepted that the observed continental heat flow c^n 

largely be attributed to heat generated by the radioelements. Thus a knowledge of the distribution of these 

heat-producing elements in the rocks in which heat flow 

is measured is essential for meaningful interpretation.

The geochemistry of thorium and uranium has be<m 

ably summarized by Adams, Osmond, and Rogers 

(1959), and many investigators have studied the d'^- 

tribution of thorium and uranium in several magmatic 

differentiation series (for example, Whitfield and others, 

1959; Larsen, 3d, and Gottfried, 1960; Gottfried and 

others, 1962, 1963; Heier and Rogers, 1963; Phair and 

Gottfried, 1964; and Kolbe and Taylor, 1966a, b). The 

relationship between radioelement content and rad: ogenic heat has been examined in detail by Birch (1954, 

1965), Verhoogen (1956), MacDonald (1964), Wass*rburg, MacDonald, Hoyle, and Fowler (1964), and 

Wollenberg and Smith (1964, 1968a, b).

Previous studies of radioactivity of rocks in 1he 

Boulder batholith region were made under the auspices 

of the U.S. Atomic Energy Commission in connection 

with the intensive prospecting for uranium in the 

northern part of the batholith from 1949 to IS 56 

(Becraft, 1956; Bieler and Wright, 1960; Wright and 

Bieler, 1960). In conjunction with this exploration program for uranium deposits, fundamental studies on the 

distribution of thorium and uranium in fresh, unaltered 

batholith and prebatholith and postbatholith volcanic 

rocks were also initiated to better understand the

El
E2 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

behavior of these elements during magmatic differentiation. In recent years, the geologic mapping of the 

Boulder batholith and vicinity has been nearly completed, thereby making it possible to evaluate the data 

on thorium, uranium, and potassium distribution in 

light of a better understood igneous history of the 

region.

In this report, data on about 150 samples are presented, correlated with their rock chemistry, and 

compared with data on samples from selected igneous 

rock series of the United States and elsewhere in the 

world. In addition, radiogenic heat production, calculated from the average radioelement content of the 

samples, is compared with preliminary heat-flow data 

on the Boulder batholith.

Analyses for thorium and uranium were obtained by 

wet chemical methods. During the early stages of the 

study, thorium was determined by the chemical method 

of Levine and Grimaldi (1958), which subsequently has 

been greatly simplified with the use of arsenazo III as 

the reagent for thorium (May and Jenskins, 1965). 

Most of the thorium data in this report were obtained 

by the arsenazo III method, which yields results reproducible to ± 10 percent for thorium contents as low as 

a few parts per million. Uranium contents were determined by the fluorimetric method of Grimaldi, May, 

and Fletcher (1952) adapted to concentrations of 

uranium commonly found in igneous rocks. With the 

fluorimetric method, uranium contents can be determined with a precision of ± 10-15 percent for concentrations greater than 1 ppm; however, for concentrations 

from 0.5 to 1 ppm, the analytical uncertainty may be 

as great as ± 50 percent.

A comparison of thorium and uranium values obtained by the methods used in this study with those 

determined by neutron activation, isotope dilution, and 

gamma-ray spectrometry for four standard rock samples 

is given in table 1. The agreement between results from

TABLE 1. Interlaboratory comparison of results of analyses, in 

parts per miUion, for thorium and uranium on four standard 

rock samples

[Chemical method: Roosevelt Moore and Esma Campbell (this rept.). Neutron 

activation and gamma-ray spectrometry: Morgan and Heier (1966). Delayedneutron method: Hamilton (1966)]

Sample No. 

and rock type

Chemical 

method

Neutron 

activation

Gammaray spectrometry

Isotope Delayeddilution neutron

method

Thor- Ura- Thor- Ura- Thor- Ura- Thor- Ura- Uraium ni- ium ni- ium ni- ium ni- nium

um um um urn

G-2,granite.___ 21.5 

GSP-1, granodiorite..-.......... 100

AGV-1, andesite... 6.1 

BCR-1, basalt...- 6.2

2.0 24.1 2.16 25.7 2.1 124.3 11.94

2.2 

2.0 

1.6

6.47 2.17

6.00 1.81

106

6.4

6.1

1.7 H06 22.4 

1.9 86.27 "1.96 

1.6 ...............

1.64

1.80

1.47

1.44

1 Doe, Tatsumoto, Delavaux, and Peterman (1967).

* Peterman, Doe, and Bartel (1067).

3 Mitsunobu Tatsumoto (unpub. data, 1968).

these independent methods is highly satisfactory and 

indicates that the accuracy of the determinations is of 

the same order as the precision.

ACENO WLEDGM ENTS

We wish to express our gratitude to David D. 

Blackwell, Southern Methodist University, Dallas, 

Tex., and to our colleague Eugene C. Roberteon, U.S. 

Geological Survey, for kindly providing their underground samples from the Butte district and their heatflow data in advance of publication. Robertson, along 

with Harry W. Smedes, Geological Survey, critically 

read an earlier version of the manuscript and suggested 

many ways to improve it. Thanks are also due 

Randolph Chapman, presently at Trinity College, 

Hartford, Conn., for collecting many of th^ samples 

analyzed in this report and Roosevelt Moore, Esma 

Campbell, Paul Elmore, and other chemists in the 

Geological Survey for analytical data. We also benefited from discussions of mutual problems with Michael 

Fleisher and Zell E. Peterman, Geological Survey, who 

also drew our attention to some of the Russian literature on thorium and uranium. Earlier phases of this 

study were done on behalf of the Division of Research 

of the U.S. Atomic Energy Commission.

GEOLOGIC SETTING

The geologic setting of the composite Boulder 

batholith and satellitic plutons has been described 

elsewhere and need only be summarized briefly here 

(Knopf, 1957, 1963; Smedes, 1966a; Doe and others, 

1968; Tilling and others, 1968). The Boulder batholith 

is exposed over an area of approximately 2,rOO square 

miles. It cuts rocks ranging in age from early Precambrian (pre-Beltian metamorphic rocks) to Late 

Cretaceous (Elkhorn Mountains Volcanics) and is cut 

and unconformably overlain by the Lowknd Creek 

Volcanics of early Eocene age and by younger rocks 

(Smedes and Thomas, 1965).

At its type locality, the Elkhorn Mountain? Volcanics 

consists of pyroclastic and epiclastic volcanic strata, 

lavas, and welded tuffs having a combined stratigraphic thickness of more than 10,000 feet and ranging 

in composition from basalt to rhyolite (Khpper and 

others, 1957; Smedes, 1966a). Because of th«.ir similar 

lithology and stratigraphic position, Upper Cretaceous 

volcanic and clastic rocks in the Wolf Creek area to 

the north of the Elkhorn Mountains area r.nd in the 

Three Forks and Maudlow areas to the south and east 

(fig. 1) are considered to be grossly contemporaneous 

with the Elkhorn Mountains Volcanics (Robinson, 

1963; Robert G. Schmidt, oral commun., 1968). Smedes 

(1966a, p. 21) suggested that the Upper Cretaceous
THORIUM, URANIUM, POTASSIUM, HEAT PRODUCTION, BOULDER BATHOLITH, MONT. Evolcanic pile represented by rocks in all these areas 

may have covered as much as 10,000 square miles. 

Samples from all these areas are included in this study. 

Although the Elkhorn Mountains Volcanics is cut 

by even the earliest rocks of the Boulder batholith, 

geologic evidence and K-Ar age data indicate that the

113° 112° 111"

47

46° 

20

I

EXPLANATION

40 MILES 

I

Post-Lowland Creek volcanic rocks

Lowland Creek Volcanics

Rocks of Boulder batholith

Elkhorn Mountains Volcanics 

and correlatives

Contact

Dashed where approximate

FIGURE 1. Areal distribution of igneous rocks in the Bouldei 

batholith region. The outcrop areas of the postvolcanic rocks 

are only partly delimited and represent the areas sampled for 

this study. (Modified from Robinson and Marvin, 1967.)

prebatholith volcanism and the onset of batholit1! 

emplacement were separated by only a very short tim^ 

interval, not detectable geochronometrically, for both 

events are dated as ~78 m.y. (million years) B.F. 

(Robinson and others, 1968; Tilling and others, 1968).

The composition of the batholith ranges from 

syenogabbro to leucogranite; rocks of granodiorite 

and quartz monzonite composition form about 95 

percent of the exposed batholith (fig. 2). In general, 

the younger batholithic rocks are more felsic than th<* 

older ones. Earliest in the intrusive sequence are tin 

mafic rocks (syenogabbro, syenodiorite, and monzonite), 

which occur as plutons near the margin of the batholith. 

Next in the intrusive sequence are granodiorite plutonr. 

All these are cut by the Butte Quartz Monzonito, 

which is the largest single pluton of the batholith and 

constitutes about 80 percent of the total area of th°> 

batholith. A comparison of the three granodiorite 

plutons included in this study shows that the Unionvilta 

Granodiorite and Burton Park plutons are distinctly 

more mafic than the Rader Creek pluton (fig. 2).

Field and petrographic evidence demonstrates that 

a continuous genetically related series exists between 

the Butte Quartz Monzonite, its silicic variants, and 

alaskite. Both sharp and gradational contacts wer^ 

observed between various members of this series, evei 

within a single outcrop; however, where sharp contact" 

separate any two members, the more felsic of the two 

generally is the younger. The few economic uranium 

prospects (now inactive) in the Boulder batholith 

region are restricted to hydrothermal veins, which cut 

the Butte Quartz Monzonite or its related silicic facier 

and are known to occur only in the northern part cf 

the batholith.

Latest in the intrusive sequence in the batholith ar^ 

leucogranodiorites and leucoquartz monzonites (grouped 

simply as "leucocratic rocks" in fig. 2 and subsequent 

data tables), which invariably are in sharp contact 

with the Butte Quartz Monzonite and older rocks.

The Boulder batholith is fringed by numeroir 

satellitic plutons, only the largest of which are show^i 

in figure 2. Because these satellitic bodies are widely 

separated and intruded into country rock of diverse 

ages, they cannot confidently be assigned position^1 

in the intrusive sequence of the batholith. However, 

K-Ar ages on biotite and hornblende from several cf 

these plutons fall within the range of ages obtained 

for the batholith proper (Tilling and others, 1968). 

Several samples from satellitic plutons are included 

in this paper, as well as some samples of mafic inclusion-" 

in the batholith rocks.

Approximately 20 m.y. after the emplacement of 

the leucocratic rocks, the youngest rocks of the batholith, the Lowland Creek Volcanics was extruded in
SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

_112D 3Q1 112°00'

460 30'h46°00'

15 MILES

FIGURE 2. Generalized geologic map of the Boulder batholith and vicinity. (Modified from Tilling and others, 196" fig. 1.)
THORIUM, URANIUM, POTASSIUM, HEAT PRODUCTION, BOULDER BATHOI/ITH, MONT. E5

EXPLANATION

Lowland Creek Volcanics, post-Lowland Creek volcanic rocks, bedded sedimentary rocks, terrace 

gravels, and alluvium

Leucocratic rocks

Age relations among these units not known 

bg, biotite granite of Knopf (1963) 

ba, biotite adamellite of Knopf (1963) 

he, Hell Canyon pluton 

me, Moose Creek pluton 

c, Climax Gulch pluton 

d, Donald pluton

Satellitic plutons

flocks of diverse composition whose positions 

in the intrusive sequence are not known

Butte Quartz Monzonite and related silicic facies 

a, alaskite, aplite, and pegmatite 

h, Homestake pluton; locally grades into alaskite and into Butte

Quartz Monzonite 

pr, Pulpit Rock pluton; generally grades into but locally cuts

Butte Quartz Monzonite 

bqm, Butte Quartz Monzonite; includes and is coextensive with

Clancy Granodiorite

Granodiorite

Age relations among these units not known 

ug, Unionville Granodiorite 

re, Rader Creek pluton 

bp, Burton Park pluton

Mafic rocks

Syenogabbro, syenodiorite, monzonite and related rocks

Elkhorn Mountains Volcanics 

Includes intrusive rocks correlated with the volcanics

Prevolcanic rocks

Include strata of Mesozoic, Paleozoic, and late Precambrian age 

and metamorphic rocks of early Precambrian age

Contact 

Dashed where inferred

FIGTJBE 2. Continued.

339-847 O - 69 - 2
E6 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

early Eocene time (48-50 m.y.) onto the eroded surface 

of the batholith (Smedes and Thomas, 1965). These 

volcanic rocks, which occur in the southwestern part 

of the Boulder batholith region (fig. 1), consist mainly 

of quartz latitic to rhyolitic flows, pyroclastics, welded 

tuffs, and reworked volcanic debris (Smedes, 1962). 

Dikes, probably feeders associated with the Lowland 

Creek Volcanics, locally injected the batholith and 

associated hydrothermal veins. In addition to samples 

of Lowland Creek Volcanics, three samples of basalts 

of probable early Tertiary age from the Three Forks 

and Wolf Creek areas have been analyzed in this study. 

Although these three basalts may well be contemporaneous with part of the Lowland Creek Volcanics, 

they are not considered as part of the Lowland Creek 

volcanic field.

Another period of Tertiary volcanism is represented 

by rhyolite plugs, dikes, and flows, which crop out 

principally in the northern and northwestern part of 

the Boulder batholith region (fig. 1). Field relations 

(Ruppel, 1961, 1963; Smedes, 1966a; Knopf, 1913) 

demonstrate that these rocks are younger than the 

Lowland Creek Volcanics and may be as young as 

Miocene or Pliocene. In this report, these rocks are 

termed "post-Lowland Creek volcanic rocks."

Igneous rocks of the Boulder batholith region are 

grossly similar in chemical composition and characterize 

the region as a calc-alkalic igneous province; the rocks 

of the batholith have a lime-alkali (Peacock, 1931) 

index of about 58. Although minor differences exist, 

the prebatholith volcanic rocks are compositionally 

similar to the older and more mafic rocks of the batholith (m, ug, bp, re, and bqm of fig. 2), and the postbatholith volcanic rocks are similar to the younger 

and more felsic batholith rocks (pr, h, a, and "leucocratic rocks" of fig. 2). Exceptions are the three postbatholith basalt samples from the Wolf Creek and 

Three Forks areas (designated as "other lower Tertiary 

igneous rocks" in tables 3 and 11 and fig. 5).

DISTRIBUTION OP THORIUM, URANIUM, AND POTASSIUM IN IGNEOUS ROCKS OF THE BOULDER 

BATHOLITH REGION

PREBATHOLITH VOLCANIC BOOKS

When plotted against selected chemical parameters 

(fig. 3), thorium and uranium in prebatholith volcanic 

rocks (table 7) reveal considerable overlap but nonetheless define several fields according to their areas of 

occurrence. With exception of a few samples, the 

analyzed prebatholith volcanic rocks contain less than 

10 ppm Th and less than 4 ppm U. In general, samples 

from the Wolf Creek area are highest in thorium and 

uranium and have the highest Th/U ratio (table 3). 

Figure 3A shows a positive correlation between SiO2 and

both thorium and uranium for samples from the Elkhorn Mountains Volcanics and the Wolf Creek area. For 

the Three Forks samples, there may be no correlation 

between SiO2 and thorium and uranium, though a weak 

negative one is suggested. Figure 3(7 suggests that both 

thorium and uranium tend to increase with decreasing 

CaO/(Na2O+K2O), although this relationship is much 

better illustrated by data for the batholith (fig. 4(7). 

Numerous workers have described a systematic increase 

of thorium and, less systematically, uranium content 

with increase in potassium content (Lyons, IS 64; Heier 

and Rogers, 1963; Whitfield and others, 195«). These 

relations, however, are at best only feebly demonstrated 

by the prebatholith volcanic rocks of the Boulder 

batholith region (fig. 3B).

BATHOLITH BOCKS

Sixty chemically analyzed rocks representative of the 

major plutons of the Boulder batholith have been 

analyzed for thorium and uranium in tl is study 

(table 8). A plot of the, thorium and uranium contents 

of these samples against selected chemical parameters 

(fig. 4) illustrates the pattern of increasing thorium and 

uranium with increasing SiO2 commonly observed for 

calc-alkalic rock series; the correlation of thorium and 

uranium concentration with bulk rock composition is 

particularly well demonstrated if the data are plotted 

against CaO/(Na,O+K»0) (fig.40).

Although there is much scatter, the plotted data 

show that each pluton, or group of similar plutons, 

of the batholith has a characteristic range of thorium 

and uranium. With the exception of two samples, the 

batholith rocks have less than 10 ppm U, the older 

rocks (the mafic rocks and granodiorites) generally 

having less than half that amount. Similarly, the older 

rocks generally contain less than 15 ppm Tl, whereas 

the younger and more felsic rocks contain more than 15 

and as much as 42 ppm Th. With exception of three 

samples, only the alaskites contain more than 20 ppm 

Th. Thorium and uranium contents of mafic inclusions 

in the batholith rocks (table 9) and of the satellitic 

plutons (table 8) are comparable to those of the older 

batholith rocks.

POSTBATHOLTTH VOLCANIC BOCK'S

Thorium and uranium contents of postbatholith 

volcanic rocks (tables 10-12) also define distinct fields 

when plotted against SiO2 , K2O, and CaO/(Na 2O-f K2O) 

(fig. 5). Samples of the Lowland Creek Volcanics and 

the other lower Tertiary samples are characterized by 

lower average thorium and uranium contents in comparison with the post-Lowland Creek rocks (table 3). 

In a gross way, the variation in thorium and uranium 

abundance can be correlated with rock composition.
MILLION PER PARTS IN URANIUM, 5 

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E8 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

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E10 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

Figure 5A, G demonstrates that thorium and uranium 

increase exponentially with increasing SiO2 and decreasing CaO/(Na2O+K2O). Even though the data are 

much more scattered, thorium, in general, increases 

with increasing K2O in all the postbatholith samples. 

However, although uranium for the Lowland Creek 

Volcanics and other lower Tertiary samples varies but 

little with variation in K2O, uranium for post-Lowland 

Creek samples increases with increasing K2O (fig. 5J3). 

Despite differences in rock composition and in abundance of thorium and uranium, the average Th/U 

ratios of all the postbatholith rocks differ only slightly, 

ranging from 4.0 to 4.7.

SUMMARY AND COMPARISON OF THORIUM, URANIUM, AND POTASSIUM ABUNDANCE DATA

The satellitic plutons have the lowest average contents of thorium and uranium observed for the batholith 

(table 2); however, the number of samples analyzed 

(six) is probably not sufficient to adequately represent 

these bodies, for, though generally small, they are 

abundant and have diverse composition. Among the 

units of the batholith proper, the rocks early in the 

intrusive sequence have lower thorium and uranium 

contents than those later in the sequence, primarily 

because the early rocks are more mafic. However, compositional control on thorium and uranium abundance 

is not the only factor involved as shown by comparison 

of the granodiorite units. Although granodiorites of the 

Rader Creek pluton are decidedly more felsic than 

granodiorites of the Burton Park and Unionville 

Granodiorite plutons, they contain the lowest amounts 

of thorium and uranium observed for the granodioritic 

rocks (table 8).

The average radioelement (thorium, uranium, and 

potassium) content of the batholith, weighted according 

to area! abundance of constituent rocks, is 3.3 percent 

K, 15.4 ppm Th, 3.9 ppm U; the Th/U ratio is 4.7 

(table 2).

The youngest rocks of the batholith do not contain 

the most thorium and uranium; the lower cor tents of 

thorium and uranium in these rocks relative to the Butte 

Quartz Monzonite and related rocks may be in part because they are not the most felsic rocks of the batholith, 

even though they are the youngest. In addition, in the 

youngest rocks Na2O generally is greater thm K2O, 

whereas in all other batholith rocks K2O predominates 

over Na2O (table 8). Thus, the youngest rc^ks apparently depart from the typical calc-alkalic differentiation trend in which the youngest rocks are highest in 

K2O and SiO2 as well as in thorium and uranium. That 

the Boulder batholith may not represent a simple calcalkalic differentiation series is suggested also by lead 

and strontium isotope data, which indicate that the 

leucocratic rocks (of which only the Hell Canyon and 

Donald plutons were analyzed isotopically) and the 

rocks of the Rader Creek pluton differ significantly in 

isotopic makeup from all other rocks of the I Hholith 

and from each other (Doe and others, 1968).

Average Th/U ratios of the batholith range from 4.0 

to 5.8, with no apparent relation to bulk rock composition or to position in the intrusive sequence. Only for 

the Butte Quartz Monzonite and its silicic differentiates 

is any possible systematic variation in Th/U ratio observed. The average Th/U ratio is 4.5 for tH Butte 

Quartz Monzonite, 4.7 for its silicic facies, and 4.9 for 

the alaskites. Thus for the Butte Quartz Monzonitealaskite series, which constitutes about 80 percent of the

TABLE 2. Summary of thorium, uranium, and potassium values and weighted average values for rocks of the Boulder batholith 

[Rocks listed according to position in Intrusive sequence from oldest to youngest (except for satellitic plutons). Data from table 8]

. . Number of 

Map unit (fig. 2) Samples

Mafic rocks (m) __ . ............

Granodiorite 

Mafic (ug, bp) 2. ___ . ___ .... _ . .......

Felsic (re) _____ ... ___ .

Butte Quartz Monzonite (bqm) 3.. . .

Silicic facies of the Butte Quartz Monzonite (pr, h). . 

Alaskites (a)* ....................

Leucocratic rocks (he, d, c) .......

Satellitic plutons (s) _____ . ___ . ..

Average (weighted according to areal abundance of constituent plutons) ..................

4

5 

7 

15 

6 

5 

12 

6

Estimated 

areal 

abundance 

(percent of 

exposed 

batholith)

0.5

4.5 

4.5 

73.0 

4.0 

1.0 

7.5 

5.0

Potassium (percent)

Range

2.3-3.1

2.0-3.4 

2.1-3.6 

1.8-3.7 

3.3-4.1 

3.9-4.9 

2.4-3.4 

1.6-4.0

Average

2.7

2.8 

2.5 

3.4 

3.6 

4.5 

2.9 

2.6

3.3 .

Thorium (ppm)

Range

2.7-10.7

8. 8-16. 9 

5.4-12.6 

11.8-19.0 

14.9-38.5 

26. 0-42. 0 

7.6-30.7 

2. 5-11. 1

Average

6.2

11.0 

7.3 

16.2 

22.3 

36.3 

15.7 

5.9

15.4 ..

Uranium (ppm)

Range

0.4- 2.3

1.7-5.7 

.8-2.7 

1.6-7.1 

2.6-12.1 

4.4-20.0 

1.6-8.8 

.7- 2.3

Average

1.5

3.4

1.5 

4.0 

5.9 

9.2 

4.1 

1.4

3.9 .

Th/U

Range

2.6-6.7

2. 8- 5. 5 

3.4-9.2 

2.7-11.2 

1.6-7.9 

2.1-6.9 

1.9-6.5 

1.6- 5.8

Average 1

4.8

4.0 

4.8 

4.0 

4.7 

4.9 

4.4 

4.5

84.7

 Computed from individual Th/U ratios, not from average thorium and uranium.

2 Age relations between the granodiorite units (ug, bp, re) cannot be determined because these rocks are separated spatially (see flg. 2). The Unfonville Qranodiorite (ug) 

and Burton Park pluton (bp) are arbitrarily placed earlier in the intrusive sequence because of their more mafic composition. 

»Excluding samples 54C-248 and 52C-10a which are xenolith-rich mafic border facies. 

1 Excluding the granite porphyry sample (5T-29a). 

s Calculated from average Th/U ratios of the batholith units and not from weighted average thorium and uranium.
THORIUM, URANIUM, POTASSIUM, HEAT PRODUCTION, BOULDER BATHOLITH, MONT. EJ1

exposed batholith, the Th/U ratio appears to increase 

slightly with differentiation, although the increase may 

not be statistically significant because of analytical 

uncertainties (p. E2).

In terms of bulk rock composition and thorium and 

uranium content, the Elkhorn Mountains Volcanics is 

grossly similar to the oldest rocks of the batholith, the 

mafic rocks (table 3). This relationship is consistent 

with field and geochronometric evidence, which indicates that the Elkhorn Mountains Volcanics and the 

oldest batholith rocks were separated by an extremely 

short time interval. However, the average Th/U ratio 

of 3.2 for the Elkhorn Mountains Volcanics contrasts 

with that of 4.8 for the mafic rocks of the batholith. In 

fact, average Th/U ratios of all the prebatholith volcanic rocks studied are lower than average ratios of the 

batholith rocks, if the single volcanic sample from the 

Maudlow area and the mafic granodiorites are omitted. 

Similarly, excluding the three basalt samples, the postbatholith volcanic rocks also have lower average Th/U 

ratios than the batholith rocks (compare table 2 with 

table 3).

With few exceptions, both the prebatholith and postbatholith volcanic rocks are characterized by lower 

average Th/U ratios than rocks of the Boulder batholith. This difference in Th/U ratio no doubt is partly 

due to differences in rock composition; however, the 

fact the the combined range in chemical composition 

of the prebatholith and postbatholith volcanic rocks 

is similar to that of the batholith suggests that rock 

composition cannot be the sole factor causing this 

difference. Although presently available data are inconclusive, the possibility exists that the difference in 

Th/U ratio might stem in part from fundamental differences in the geochemical behavior of thorium and 

uranium under conditions of plutonism as opposed to 

volcanism. A similar explanation has recently been invoked to partly explain variations in cesium distribution 

in extrusive basalts versus hypabassal intrusive basalts 

(Gottfried and others, 1968).

NATURE OF VARIATION IN THORIUM 

AND URANIUM CONTENT

Primary magnetic abundances of thorium and uranium can be modified by later alteration (Hurley, 1950; 

Neuerburg and others, 1956; Brown and Silver, 195*>; 

Tilton and others, 1955; Larsen, 3d, 1957; Larsen, Jr., 

and Gottfried, 1961; Ragland and others, 1967). 

Therefore it is essential to evaluate whether the observed variations in thorium and uranium are predominantly due to primary or secondary processes.

To minimize the possibility of obtaining secondary 

variations in thorium and uranium content, the rocvs 

analyzed in this study were carefully collected to avoid 

zones of hydro thermal alteration and (or) faulting; 

the samples analyzed appeared fresh both in hand 

sample and in thin section. Petrographic study indicated that sphene is a common primary accessor 

mineral in nearly all the batholithic rocks. Allanite of 

probable deuteric origin was found only in trace 

amounts in many of the batholith rocks but is absent 

in the mafic rocks and mafic granodiorites. However, 

there is no apparent correlation between the absence or 

presence of these thorium- and uranium-rich minerr Is 

and the observed thorium and uranium content of t\e 

host rock. With the exception of the glassy welded 

tuff from Maudlow (table 7), which has an anomalously 

low content of K2O relative to the other prebatholith 

volcanic rocks, the major-element compositions also 

do not suggest any alteration of the rocks. Therefore, 

because of the lack of contrary evidence, the distribution 

of thorium and uranium in igneous rocks of the region 

was assumed to be predominantly primary.

TABLE 3. Summary of thorium, uranium, and potassium values for prebatholith and postbatholith volcanic rocks compared with weighted

average values for the Boulder batholith

[Data from tables 7, 10,11, and 12]

Number of Potassium (percent) Thorium (ppm) Uranium (ppm) Th/U

Range Average Range Average Range Average Range Average

Prebatholith volcanic rocks:

Elkhorn Mountains volcanic field._.______..___.. 10 1.7-5.0 2.6 2.5-8.9 6.6 .7-3.0 2.1 1.5-4.8 3.2 

Three Forks area........................................... 7 1.1-2.8 2.4 2.7-14.4 6.0 .8-6.0 2.9 1.6-9.6 2.4

Wolf Creek area............................................. 4 .7-6.0 3.5 6.8-30.9 16.6 2.0-5.6 3.7 3.0-5.5 4.2

Maudlow area_____...._____.___...._____ 1 . .5 ... 17.5 __.___ 2.6 ______ 6.7

Boulder batholith (weighted average from table 2)....__...... 60 1.6-4.9 3.3 2.5-42 15.4 .4-20.0 3.9 1.5-11.2 4.7

Postbatholith volcanic rocks:

Lowland Creek Volcanics (early Eocene).........__....... 11 1.9-4.4 2,9 4.0-20.2 9.0 .8-4.5 2.5 .9-13.4 4.3

Other lower Tertiary igneous rocks__.__.___.__... 3 1.8-2.6 2,2 2.1-7.9 4.7 .4-2.1 1.1 3.8-5.3 4.7 

Post-Lowland Creek volcanic rocks (Miocene or Pliocene).. 10 2.3-4.6 3.5 3.2-44 21.9 2.1-18.0 6.1 1.5-7.2 4.0
E12 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

A test of the validity of the assumption that variations in thorium and uranium are indeed primary was 

provided by data on a suite of hydrothermally altered 

Butte Quartz Monzonite collected from several underground workings in the Butte district (table 13). 

Some of these show only slight argillic and sericitic 

alteration and contain minor sulfides; others are very 

intensely altered and contain abundant sulfides. In 

light of data on the ease of leaching uranium, and to 

a lesser extent thorium, it was anticipated that the 

uranium and thorium values for these samples which 

have clearly interacted with hydrothermal fluids should 

be erratic, depart from primary values, and yield 

anomalous Th/U ratios. However, a comparison of 

data on these altered Butte Quartz Monzonite samples 

with data on their fresh, unaltered counterparts 

indicates that the thorium and uranium distribution 

for both are about the same (table 4).

TABLE 4. Comparison of the thorium and uranium distribution 

between hydrothermally altered Butte Quartz Monzonite samples 

and their fresh, unaltered counterparts

[Data from tables 8,13, and 14]

Butte Quartz Number Thorium (ppm) Uranium (ppm) Th/U Monzonite of 

Samples samples Range Average Range Average Range Average

Hydrothermally 

altered____

Fresh, unaltered 

(surface) ....

Fresh, unaltered 

(drill hole).....

14 12.1-25.8 17.1 2.2-8.8 4.4 2.2-6.2 4.3

14 11.8-19.0 16.2 1.6-7.1 4.0 2.7-11.2 4.0

19 12.8-32.4 22.8 3.5-11.8 6.3 2.1-6.3 3.7

This rather unexpected result can be interpreted as 

either (1) the alteration had little or no effect on the 

primary thorium, and uranium distribution or (2) 

what appear to be unaltered samples are in fact also 

altered. The second interpretation does not seem 

reasonable, because it would require that the entire 

mass of Butte Quartz Monzonite be pervasively, and 

uniformly, affected by ore fluids associated with the 

Butte mineralization. Such a large-scale alteration, 

involving distances as great as 60 miles, can be rejected 

on the basis of isotopic studies (Doe and others, 1968). 

Though the apparent lack of difference in thorium and 

uranium distribution between fresh and altered samples 

is puzzling, the first interpretation nonetheless cannot 

be excluded. If the first interpretation is assumed to 

be valid for all samples, then the observed variations 

in thorium and uranium are probably predominantly 

primary variations, disturbed little or not at all by 

later alteration processes.

Data on another suite of Butte Quartz Monzonite 

samples from a drill hole in the Butte district (table 14) 

provide a means of testing the possibility that thorium 

and uranium distribution might vary with depth. The 

samples from this drill hole, which are also discussed

in connection with heat-flow data (see p. E18), are 

extremely fresh, although a few contain thin veinlets 

(0.5-1.5 mm) of sulfides. The depth of the samples 

ranges from approximately 850 to 4,000 feet Examination of table 14 reveals that there is no systematic 

variation of thorium and uranium with depth and that 

the thorium and uranium contents of the drill-hole 

samples are approximately 50 percent higher tl an those 

typically observed for the Butte Quartz Monzonite 

(compare tables 8 and 14). Although the drill-hole 

samples have values of SiOz, alkalies, CaO/(Na2O+K2O) 

typical to those of the Butte Quartz Monzonite, their 

average thorium and uranium content is comparable 

instead to that of the silicic fades of the Butte Quartz 

Monzonite (table 8).

In summary, available data support the assumption 

that the thorium, uranium, and potassium distribution 

in igneous rocks of the Boulder batholith region is 

predominantly primary and that the distribution 

observed does .not vary with depth, at least ir a 4,000- 

foot interval.

COMPARISON OF THORIUM AND URANIUM EISTRIBUTION BETWEEN CONTRASTING MAGMA SFRIES

It is beyond the scope of this report to summ arize and 

interpret all the available data on thorium and uranium 

in igenous rocks for comparison with our data. Moreover, pertinent petrochemical and geologic information 

necessary for meaningful interpretation of much of the 

existing thorium and uranium data is not available, not 

known, or obscured by postcrystallization phenomena. 

Therefore, reference is made only to several igneous 

rock suites (table 5) which were chosen for comparison 

because:

1. The petrochemistry and geologic history of these 

suites are reasonably well known.

2. The suites selected represent a wide rang^ of magmatic provinces and tectonic settings.

3. The suites selected are Cretaceous or younger, thereby minimizing postcrystallization modification 

which affects many of the older suites.

4. Most of the suites selected encompass a vdde compositional range, representing most stages of magmatic differentiation and thus avoiding comparison 

of thorium and uranium distribution on the basis 

of random rock types alone without reference to 

relative stage of differentiation.

5. The suites selected probably bracket all th e possible 

variation patterns of thorium and urar^um with 

differentiation undisturbed by postcrystallization 

events.

For ease of such comparison, the thorium and uranium 

data of these selected reference suites are plotted against
THORIUM, URANIUM, POTASSIUM, HEAT PRODUCTION, BOULDER BATHOLITH, MONT. El 3

TABLE 5. Lime-alkali indices and median ThfV ratios of selected 

suites of igneous rocks

Refer- References

ence Locality Lime- Median 

suite alkali- Th/IT Thorium and Chemical and

in fig. 6 index ratio uranium data geologic data

1 .... Kamchatka, 64 1.2

U.S.S.R. 

2__.. Mariana Islands.. 65 1.2-2.9

3__.. Mount Garibaldi, 64 1.6 

British Columbia.

4____ Strawberry Mts., 63 2.6 

Oreg.

5-....- Lassen, Calif....- 64 2.7

6___. Modoc, Calif.....

Shavrova (1958,

1961). 

Gottfried, Moore,

and Campbell

(1963).

Shavrova (1958,

1961). 

Schmidt (1957);

Gilbert Corwin

(oral

commun., 1967);

Stark (1963). 

.do-.. - - Mathews (1957).

.do.._........ Thayer (1957).

Larsen, 3d, and Williams (1932).

Gottfried (1960). 

60 2.8 .....do 

7___.. JemezMts., N. 58 3.4 

Mex.

.doBig Bend, Tex... 51 2.8

Virginia.

Southern California batholith.

48 3.7

64 3.5

Gottfried, Moore, 

and Caemmerer 

(1962).

.doLarsen, 3d. and 

Gottfried (1960); 

Larsen, Jr., and 

Gottfried (1961).

Powers (1932); 

Anderson (1941).

R. L. Smith and 

R. A. Bailey 

(oral commun., 

1967). 

Lonsdale and Maxwell (1949); J. T. 

Lonsdale (written commun., 

1962).

Charles Milton 

(oral commun., 

1962).

Larsen, Jr. (1948).

SiO 2 content (fig. 6.4); the use of a differentiation index 

other than SiO 2 would not result in significantly 

different configuration of the plots.

A comparison of the thorium and uranium variation 

curves (fig. 6.4) for a given petrographic province indicates a rather strong geochemical association of these 

elements over a wide span of differentiation; accordingly, the Th/U ratio remains fairly constant. However, 

the Th/U ratio does vary between igneous rock series 

representing different magma types. The median Th/U 

ratios of the reference suites (table 5) show a gross 

correlation with their lime-alkali indices. With exception 

of the Southern California batholith, the calcic volcanic 

suites seem to have significantly lower Th/U ratios 

than those of the alkali-calcic and alkalic series of the 

continental interior regions. Similar variations of Th/U 

ratio with geologic setting have been noted by Heier 

and Carter (1964) for tholeiitic basalts: an average of 

1.5 for those of orogenic belts as compared with an 

average of about 4 for those of the plateau type. Doe 

(1967) also observed a tendency for higher Th/U ratios 

to occur in rocks of the continental interior than in 

rocks of the west coast of the United States.

Thorium and uranium in the reference suites (fig. 6) 

show a strong correlation with the lime-alkali (Peacock, 

1931) index of the given suite, which in turn is influenced 

by tectonic setting. Reference suites 1-8 are of volcanic 

origin; reference suite 9 represents a dike complex. 

The thorium and uranium patterns in these reference

suites are discussed briefly and then they are compared 

with rocks of the Boulder batholith region and with 

several other suites of plutonic rocks.

The calcic rock suites (curves 1-5, fig. 6.4) are fairly representative of the circum-Pacific petrographic province 

and of a tectonically active "island-arc" setting. In 

these suites thorium can increase gradually to about 6 

ppm (curves 3-5), remain nearly constant (curve 2), 

or decrease slightly (curve 1) with increasing Si02 . 

The uranium distribution pattern of these calcic suites 

generally follows that of thorium (fig. 6.4). Some of tH 

calcic suites represent marked exceptions to the oftenstated generalization that thorium and uranium contents increase with increasing SiOa or differentiation 

index. The Southern California batholith differs from 

the other calcic suites and is discussed later (p. El5).

The calc-alkalic reference suites represent tectonic 

associations of the continental interior, that is, tectonic 

settings east of the "quartz diorite line" of Moore (1959). 

These suites are characterized by the curvilinear 

increase of thorium and uranium with increasing SiC-, 

the increase being most pronounced in the siliceous 

end members of the suite (fig. 6.4). This relationship 

is well illustrated by the Jemez Mountains volcanic 

suite, which is predominantly calc-alkalic, but less so 

by the Modoc lavas, which have a lime-alkali index 

that nearly falls into the calcic grouping.

It is generally accepted that alkalic rocks have 

tectonic associations typical of regions of relative crustal 

stability. Curvilinear distribution of thorium ard 

uranium are also characteristic of these suites; however, 

in the rocks of alkalic affinities, both the thorium 

and uranium contents are significantly higher than in 

other igneous rocks (fig. 6.4).

Thorium and uranium distribution curves for rocks 

of the Boulder batholith region (generalized from data 

of figs. 3-5 and tables 7-12) are plotted in figure SB, 

the patterned fields of which are based on the thorium 

and uranium distribution curves of the reference suites 

in figure 6A. The Boulder batholith rocks (lime-alkrli 

index, ^58) show the curvilinear trend typical of 

calc-alkalic rocks with respect to both thorium and 

uranium contents, although the siliceous part of the 

curve actually lies within the field designated for mo^e 

alkalic rock suites. This slight departure of the batholith 

curve from the arbitrarily delimited "calc-alkalic" 

field (as shown in fig. QE) probably has little or no 

geologic significance and merely illustrates the imperfect nature of such a composite plot as well as the 

impossibility of fitting natural rock suites into artificial 

pigeonholes without having some minor overlap. Like 

the batholith rocks, the postbatholith volcanic roc^s 

have thorium and uranium distribution curves which
E14

35

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY 

87ppm \ 45ppm D

T

42ppm44ppm #

//,

Boulder batholith^ //

: : : :> :;:'. :- -: :: : ''::: :-:'!:'!: ;/ : ^ / '

40 45 50 55 60 65 70 75 80 40 45 

SiO2 , IN WEIGHT PERCENT

50 55 60 65 70 

SiO2 , IN WEIGHT PERCENT

75

EXPLANATION

Alkalic and alkali-calcic Calc-alkalic Calcic

1. Kamchatka, U.S.S.R.(64) 

3. Mount Garibaldi,

British Columbia (64) 

5. Lassen, Calif. (64) 

7. Jemez Mountains,

New Mexico (58)

2. Mariana Islands (65) 

4. Strawberry Mountains,

Oreg. (63) 

6. Modoc, Calif. (60)

8. Big Bend, Tex.(51)

9. Virginia (48)

EXPLANATION

Alkalic and alkali-calcic Calc-alkalic

PLC = Post-Lowland Creek 

volcanic rocks 

(Miocene or Pliocene)

LC = Lowland Creek Volcanics

and other lower Tertiary rocks

Calcic

>Postbatholitr

EMV = Elkhorn Mountains Volcanics ^

and correlative rocks VPrebatholith 

(Upper Cretaceous) )

FIGURE 6. A, Thorium and uranium distribution curves of selected reference igneous suites (see text and table 5). The limealkali index of suite is given in parentheses after locality name. B, Thorium and uranium distribution curves of igneous 

rocks of the Boulder batholith region and of the Southern California batholith superimposed on fields defined by the 

reference igneous suites of figure 6-4.
THORIUM, URANIUM, POTASSIUM, HEAT PRODUCTION, BOULDER BATHOLITH, MONT. E15

are characteristic of calc-alkalic rock suites but which 

also plot partly into the "calcic" field as outlined. 

The thorium curve for the prebatholith volcanic rocks 

is similar in form to, and intermediate between, the 

thorium curves for the batholith rocks and the postbatholith volcanic rocks. Similarly, the uranium curve 

for the prebatholith volcanic rocks lies between the 

curves for the batholith and for the postbatholith 

volcanic rocks; however, it does not display the sharp 

increase in the siliceous end.

The uranium distribution curve for the prebatholith 

volcanic rocks is more typical of calcic suites, but 

the thorium curve is that expected for calc-alkalic 

suites. The reason for this apparent divergence of 

trends is not known.

Th/U ratios of the igneous rocks of the Boulder 

batholith region show no systematic variation with 

respect to degree of differentiation or to age, but there 

is a tendency for the volcanic rocks, both prebatholith 

and postbatholith, to have lower ratios than the 

batholith rocks. Although the average Th/U ratios 

(tables 7, 8, and 10-12) of the igneous rocks are generally 

higher than 3.0 and thus are compatible with their 

calc-alkalic character (see table 5), mafic inclusions in 

batholithic rocks generally have Th/U ratios less than 

3.0 (table 9).

The Southern California batholith (Larsen, Jr., 

1948) is a typical representative of a calcic suite 

(lime-alkali index, ~64), yet its thorium and uranium 

distribution patterns (fig. QB) resemble more closely 

those of calc-alkalic suites (for example, the Boulder 

batholith) than those of the reference calcic volcanic 

suites (fig. 6A). The reason for this difference is not 

known, but it may reflect inherent differences in 

crystallization regimes of a plutonic versus the volcanic 

environment of the reference calcic suites. Though the 

distribution curves of thorium and uranium of the 

Boulder and Southern California batholiths are similar 

in form, they differ markedly in amounts; figure QB 

graphically demonstrates that the Boulder batholith 

is significantly higher in both thorium and uranium 

than the Southern California batholith. This difference in radioactive element content, which is ascribed to difference in petrographic province and, 

hence, tectonic setting, is also well expressed by the 

average thorium and uranium contents of these batholiths weighted according to relative areal abundance 

of the constituent rocks types:

Region

Thorium 

(ppm)

Boulder batholith (table 2, this rept.)___ 15. 4 

Batholiths of Western United States (Southern California, Sierra Nevada, and Idaho 

batholiths; Phair and Gottfried, 1964, 

table IB) 11. 4,

Southern California batholith (table 6, this 

rept.)_-__-------------- ____________ 5. 5

Uranium 

(ppm)

3 9

2,5 

1.7

Many differences in thorium and uranium related to 

bulk composition are believed to reflect primarily d*fferences of a regional or provincial nature; that is, 

different segments of the earth's crust differ intrinsically 

in their thorium and uranium content: For this reason, 

bulk composition is no universal guide to estimating 

thorium and uranium content, nor are thorium and 

uranium guides to bulk composition. To illustrate, frv^o 

examples have been chosen; the first is of similar 

thorium and uranium contents from plutons that differ 

markedly in bulk composition, and the second is of 

markedly different thorium and uranium contents frna 

plutons of closely similar bulk composition (fig. 7).

The Rader Creek granodiorite pluton and the 

Woodson Mountain Granodiorite from the Southern 

California batholith (table 15) differ significantly in 

bulk composition, having large differences in, and no 

overlap of, the SiO2 and CaO/(Na2O+K2O) values but 

nearly identical average thorium and uranium contorts 

(fig. 7). The Rader Creek pluton and plutons from the 

Snowy Mountains, Australia, are similar in bulk 

composition. The granodiorite and adamellite from the 

Snowy Mountains have distinctly higher thorium and 

uranium contents than the Rader Creek or Woodson 

Mountain plutons, yet the differences in bulk ro°<k 

composition are small (fig. 7).

This concept of one region of the crust enriched in 

thorium and uranium ("uranium and thorium provinces") relative to another has been examined in some 

detail by Phair and Gottfried (1964), who demonstrated 

that the Colorado Front Range as a whole has about 

twice as much thorium and uranium as do batholiths 

of the Western United States and the "continental 

crust" of Heier and Rogers (1963).

In summary, the distribution of thorium and uranium in igneous rocks of the Boulder batholith region 

is typical of that observed for calc-alkalic rock suites. 

The comparison of the data of this report with thorium 

and uranium data on other comagmatic rock ser«» 

attempts to take into account the dependence of the 

thorium and uranium distribution pattern on the
E16 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

t- M

M

n i r

c o

o

OL 

If) LU O

<

z 

<

Q. 

X

UJ

J> 0)

</) <

<S ~ </> 

 -CO) 

^- ^ hn

. ,

ro +-i

go > a;

S 5 <5

0) O 3

11 Jl + *

NomiiAi y3d siyvd NI ' siyvd NI 'i/\intNvyn
THORIUM, URANIUM, POTASSIUM, HEAT PRODUCTION, BOULDER BATHOLITH, MONT. E17

petrographic province, and it is concluded that in any 

calculation of average crustal abundances of thorium 

and uranium or in any scheme of the evolution of the 

radiogenic daughters of these elements, the possibility 

of wide regional ("provincial") differences should be 

considered.

RADIOGENIC HEAT PRODUCTION AND HEAT FLOW

The radiogenic heat production of igneous rocks of 

the Boulder batholith region has been calculated from 

their thorium, uranium, and potassium contents (table 

6) on the basis of Birch's estimates (1954) of heat 

generation (1 ppm Th=0.20 microcalories per gram 

per year; 1 ppm U=0.73 /jcal/g yr; 1 percent K=0.27 

Mcal/g yr). Heat-production values for the prebatholith 

volcanic rocks range from 3.4 to 7.0 ncsl/g yr. These 

values are comparable to those for the earlier and 

more mafic rocks of the batholith and for rocks of the

satellitic plutons. The younger rocks of the batholith, 

which are volumetricaHy predominant, are characterized by higher heat-production values, 7.0 to 15.2 

/ical/g yr. The average total heat production of tl^ 

batholith, weighted according to area! abundance of 

the constituent plutons, is 6.8 /ical/g yr. Of the postbatholith volcanic rocks, the post-Lowland Creek 

rocks have an average value of 9.8 /*cal/g yr, or slightfy 

more than twice the heat-production capacity (4.4 

/ical/g yr) of the Lowland Creek rocks. Insufficient data 

preclude calculating average heat-production values 

for the prebatholith and postbatholith volcanic rocks, 

weighted for rock abundance.

For comparison, values for total heat production 

of rocks from other regions are also shown in table 6. 

The major rock types of the calcic Southern California 

batholith (tonalite and granodiorite) have distinctly 

lower heat-production values than the rocks of tl «.

TABLE 6. Radiogenic heat production in igneous rocks of the Boulder batholith and in some other crystalline materials

Map unit or rock type Number of

Estimated

areal

abundance

(percent of

exposed

batholith)

Average values

Potassium 

(percent)

Thorium 

(ppm)

Uranium 

(ppm)

Total hea*. 

Gical/gyrx

Bonlder batholith region

Prebatholith volcanic rocks: 

Elkhorn Mountains volcanic field ____________________

Three Forks area.. _______________________ . _ ..

Wolf Creek area. ... __________________________ .

Boulder batholith: 

Mafic rocks __ . ____________________ ...

Granodiorite (ug, bp)... ______________ .......

Granodiorite (re). ........... . ............ . ______ . _ .

Butte Quartz Monzonite ________________________

Silicic Butte Quartz Monzonite. . _____ . ___ . __ .. . .

Alaskite. __ . ___ . __ . __ ....

Lencocratic rocks. ____________ ..

Satellitic plutons. ______ . ................

Average (weighted according to areal abundance of map units) ______ ..

..... 10 .............. 2.6

7

0 A

..... 4 .............. 3.5

..... 4 0.5 2.7

..... 5 4.5 2.8

7 4.5 2.5

 . 14 73.0 3.4

__ 6 4.0 3.6

.... 5 1.0 4.5

19 7 R 9 O

6 5.0 2.6

...... 3.3

6.6

tt n

16.6

ft 9

11.0

7.3

16.2

22.3

36.3

15.7

5.9

15.4

2.1

9 O

9 7

1.5

3.4

1.5

4.0

5.9

9.2

4.1

1.4

3.9

3.6

4.0

7.0

3.1

5.4

3.2

7.1

9.7

15.2

e.r 2.r

6.8

Postbatholith volcanic rocks:

Lowland Creek Volcanics (early Eocene) ___ . 

Post-Lowland Creek volcanic rocks (Miocene or Pliocene) -

2.9 

3.5

9.0 

21.9

2.5 

6.1

4.4 

9.8

Southern California batholith »

Gabbro ........ ___ . _____________ . ..

Tonalite _ . ___________________

Granodiorite ______________

Quartz monzonite and granite ...... ___________ ... ..

Average (weighted according to areal abundance of rock types) _______ .

..... 7 7 0.3

19 A9 1 9

24 28 2.9

2

n O Q

1 7

0.6

4.1

8 1

19.1

5.5

0.3

1.5

2 1

5.2

1.7

0.4

2.3

3.9

8.P

2.7

Sierra Nevada batholith region *

Prebatholith rocks:

Metavolcanic rocks __ .

Clastic, sedimentary rocks _____________ 

Sierra Nevada batholith:

Cretaceous plutons ___________ .

Jurassic or Cretaceous (granodiorite of Dinkey Creek)

Triassicor Jurassic rocks of eastern Sierra Nevada 278

0.14

2.40

2.77

1.88

3.78

0.98

14.5

21.3

11.0

18.6

0.45

3.31

7.17

3.56

4.29

0.6 

6.0

10.3 

5.3 

8.1

Baltholiths, Western United States 3 (Southern California, Sierra Nevada, and Idaho)

Gabbro and diorite. _ . ___________ .

Tonalite . _______________ .

Granodiorite ___________ .

Quartz monzonite, granite.. . .....

. .. ....... 17

3ft

 ............. 12

12.6

33.7

10 1

34.6

0.5

1 fi

Q ft

3.6

0.8

5.5

12.1

18.5

0.5

1.7

2.5

4.0

0.7

2.7

5.0

7.6

Average (weighted according to areal abundance of rock types). 2.4 11.6 2.5 4.7

See footnotes at end of table.
E18 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

TABLE 6. Radiogenic heat production in igneous rocks of the Boulder batholith and in some other crystalline materials Continued

Map unit or rock type Number of 

samples

Estimated

area!

abundance

(percent of

exposed

batholith)

Average values

Potassium 

(percent)

Thorium 

(ppm)

Uranium 

(ppm)

Total heat 

G«ca]/gyr)

Snowy Mountains, Australia *

 . _________ 4 .. ........

. ___ . ___ .. _____ 8 ... .......

20

3.48

.... 3.87

2.63

19.9

17.2

17.0

4.0

8.0

3.8

7 9

10.2

6.0

Cape Granites, Sontb Africa«

.. - .-..__--.. .-._.. 17 ..........

......... ................. 0 ..-.. .-

.. __ ... _ . ___ ..... __ 8 ..... .....

4.15

4.36

4.17

21.6

26.0

23.5

6.5

12.0

11.6

10.2

17.4

13.9

Canadian Precambrian shield *

Composite samples (330 rocks). 2.68 10.3 2.45 4.6

Continental crust'

2.6 10.0 2.8 4.7

Some crustal and meteoritic materials*

Chondrites.__. 

Achondrites

High calcium..

Low calcium... 

Granitic rocks... 

Basalts. __. 

Eclogites

Low uranium..

High uranium.

50/21/8

5/3/5 

1

755 

24

2/7/6 

10/12/12

0.0845

.0430

.0009

3.79

.84

.0360

.2600

.51 

.0059 

«18.5 

2.7

.18 

.45

a 012

.081

.0021

4.75

.6

.048 

.25

0.04

.17 

.003

8.2

1.2

.08 

.34

i Average potassium, thorium, and uranium values calculated from data ot Larsen, Jr. (1948), Larsen, 3d, and Gottfried (I960), and Larsen, Jr., and GoWried (1961). 

s Data of Wollenberg and Smith (1968a, b).

s Average thorium and uranium values from Larsen, 3d, and Gottfried (1960) as combined in Phair and Gottfried (1964); average K values estimated from data of 

Larsen, Jr., and Schmidt (1068), Bateman (1065), and of this report.

« Average K, Th, and TJ values taken from Kolbe and Taylor (1966a).

* Average K, Th, and U values taken from Kolbe and Taylor (1966b).

 Average K, Th, and U values taken from Shaw (1967). 

i Average K, Th, and U values taken from Heier and Rogers (1963).

s Data from literature as tabulated in Wasserburg and others (1964, table 1). Numbers of samples separated by slashes indicates the number of K, Th, and U analyses, 

respectively.

» Calculated from average Th/K ratio of 166 granitic rocks.

calcalkalic Boulder batholith; the average values for 

total heat production of these masses, weighted according to areal abundance of the constituent rocks, are 

2.7 and 6.8 M^al/g yr, respectively. The Butte Quartz 

Monzonite and its silicic facies, which compose approximately 80 percent of the Boulder batholith, 

have a heat production capacity less than that of the 

Mount Givens Granodiorite but greater than that of 

the granodiorite at Dinkey Creek of the Sierra Nevada 

batholith. Table 6 also reveals that the weighted heat 

production of the Boulder batholith is less than heatproduction values of the Snowy Mountains (Australia) 

and of the Cape Granites (South Africa) but greater 

than heat production of the Canadian Precambrian 

shield. It is noteworthy that the average radioelement 

content (hence, heat production also) of the Canadian 

Precambrian shield (Shaw, 1967) is virtually identical 

with that of the "continental crust" of Heier and 

Rogers (1963). Of the values for radiogenic heat 

production calculated from average radioelement content of crustal and meteoritic materials tabulated by

Wasserburg, MacDonald, Hoyle, and Fowler (1964), 

the value for "granitic rocks" (8.2 jxcal/g yr) approximates that for the Butte Quartz Monzonite (7.1 

Mcal/g yr) and its silicic facies (9.7 ycal/g yr).

Data by D. D. Blackwell and E. C. Robertson 

(written commun., 1968) indicate that the heat flow 

measured in a drill hole in the Butte Quartz 1 lonzonite 

of the Boulder batholith is 2.2 ^cal/cm2 sec (microcalories per square centimeter per second) and the 

heat flow calculated from measurements in the underground workings at Butte is 2.1 /teal/cm2 sec (see 

tables 13 and 14 and p. E12). These values are higher 

than the mean heat flow of the earth, 1.5 ±10 percent 

/xcal/cm2 sec (Lee and Uyeda, 1965), but are compatible 

with the mean value of 2.3 Meal/cm2 sec for six heatflow measurements from the western inter or of the 

United States (see Von Herzen, 1967, table 1) and 

with a preliminary value of 2.25 jucal/cm2 sec near 

Wallace, Idaho (Lachenbruch and others, 1967). 

Heat flow in the Rocky Mountains and western Great 

Basin generally exceeds 1.6 pcal/cm2 sec (Roy and
THORIUM, URANIUM, POTASSIUM, HEAT PRODUCTION, BOULDER BATHOLITH, MONT. EI9

Blackwell, 1966; Decker, 1966; Lachenbruch and 

others, 1967).

Calculations using mean specific gravity of 2.70 and 

heat-production values computed from the average 

radioelement content (table 14) show that the heat 

flow of 2.2 /teal/cm2 sec measured in the drill hole can 

be attributed entirely to radiogenic heat produced by a 

column of surface rock approximately 25 kilometers 

thick, if it is assumed that the radioelement distribution 

in the rock does not vary with depth. As previously 

noted (p. El2), the radioelement content of the drillhole samples is atypical, roughly 50 percent higher than 

that typically observed for the Butte Quartz Monzonite. 

Computations based on heat-production values calculated from the mean radioelement content of the 

whole Butte Quartz Monzonite * indicate that a slab of 

rock about 35 kilometers thick could produce the observed heat flow. Limited seismic data (Meyer and 

others, 1961; McCamy and Meyer, 1964) show that the 

crust in the Boulder batholith region is about 45 kilometers, which is about 10 kilometers thicker than the 

maximum thickness of the rock column (35 km) that 

would provide the necessary radiogenic heat to match 

the observed heat flow. These calculations suggest that 

radiogenic heat not only can account entirely for the 

heat flow observed but also would exceed the heat flow, 

if the radioelements were uniformly distributed throughout the entire 45-kilometer thickness of the crust.

Observed heat flow in the Boulder batholith is thus 

lower than that expected from the radiogenic heat 

production of the surface rocks, if uniform distribution 

of radioelement in the crust is assumed. This situation 

is analogous to that observed for the Sierra Nevada 

batholith (Lachenbruch and others, 1966; Bateman 

and Eaton, 1967). Lachenbruch, Wollenberg, Greene, 

and Smith (1966) have attempted to reconcile the difference between heat flow and radiogenic heat by proposing that the radioactive elements were concentrated 

in the upper part of the crust and subsequently removed 

by erosion. Whether or not a similar mechanism was 

operative in the Boulder batholith cannot be fully 

evaluated with presently available geologic and analytic 

data. However, erosion on the order of 7-10 kilometers 

of batholith since the Late Cretaceous, as suggested for 

the Sierra Nevada batholith (Bateman and Eaton, 

1967), probably did not occur in the Boulder batholith 

region, for geologic evidence indicates that the present 

erosion surface is probably nowhere more than 2-3 

kilometers from the roof of the batholith (see, for example, Ruppel, 1963). Nonetheless, the possibility that 

the radioelement content of the crust in the Boulder

> Table 4 shows that the distribution of thorium and uranium in unaltered Butte 

Quartz Monzonite is comparable with that in altered rocks of the uaderground workings at Butte where the 2.1 /teal/cm9 sec heat-flow measurement was made.

batholith region decreases with depth must be seriousl^ 

considered as a possible explanation for apparent discrepancy between heat flow and heat production.

Data presented in this report suggest that, at leaf t 

down to a depth of little more than a kilometer, ther^ 

is no decrease (or increase) in radioelement content. 

However, seismic data (McCamy and Meyer, 1964) 

suggest that material in the lower half of the approximately 45 kilometer-thick crust is characterized by 

higher seismic velocity, 7.4-7.6 km/sec (kilometers per 

second) as opposed to 6.0 km/sec for material in tl ^ 

upper half. On the basis of gravity data, Biehler ard 

Bonini (1966) and Burfeind (1967) suggested that tH 

Boulder batholith probably does not extend to deptl <> 

greater than 10-15 kilometers. Thus, geophysical 

data enhance the possibility that the lower part of ll^ 

crust is composed of denser (more mafic) material 

that is lower in heat-producing radioelements. Until 

detailed information on the subsurface configuraticn 

of the batholith and on the structure of the crust 

becomes available, it is not possible at present to 

determine the contribution, if any, of heat from lowrcr 

crustal and (or) upper mantle sources to the overs 11 

thermal budget of the crust in the Boulder batholith 

region. The limited geophysical data available, nonetheless, are compatible with the interpretation that 

the abundance of radioelement may decrease with 

depth in the crust.

In summary, the available data indicate that in tl ^ 

Boulder and Sierra Nevada batholiths radiogenic her.t 

production is probably ample to match observed heat 

flow. The data also suggest the existence of lateral 

regional ("provincial") variations in the distribution of 

radioelements, and hence of radiogenic heat production, 

in selected areas of the crust. Clearly, much more data 

are required on heat flow, especially in regions where 

crustal thickness and radioelement distribution are 

known, and on regional variation in thorium, uranium, 

and potassium distribution patterns before the inte~- 

play of conductive, convective, and radiative heat 

processes in the earth's thermal regime can be properly 

evaluated. In addition, data must be gathered en 

possible vertical variation in radioelement content in 

crustal and ultimately in mantle materials collected 

by deep drilling. The demonstration of such vertical 

variation surely would resolve many of the difficulties 

in presently proposed theories and models of the heat 

budget of the earth.

REFERENCES

Adams, J. A. S., Osmond, J. K, and Robers, J. J. W., 1959, Tl ?. 

geochemistry of thorium and uranium, Chapter 6, of Volume 3 

in Ahrens, L. H., and others, eds., Physics and chemistry of 

the earth: London, Pergamon Press, p. 298-348.
E20 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

Anderson, C. A., 1941, Volcanoes of the Medicine Lake highland, 

California: California Univ. Dept. Geol. Sci. Bull., v. 25, 

no. 7, p. 347-422.

Bateman, P. C., 1965, Geology and tungsten mineralization of 

the Bishop district, California: U.S. Geol. Survey Prof. 

Paper 470, 208 p.

Bateman, P. C., and Eaton, J. P., 1967, Sierra Nevada batholith: 

Science, v. 158, p. 1407-1417.

Becraft, G. E., 1956, Uranium deposits in the northern part of the 

Boulder batholith: Econ. Geology, v. 81, p. 362-374.

Biehler, Shawn, and Bonini, W. E., 1966, A geophysical interpretation of the Boulder batholith, Montana [abs.]: Am. 

Geophys. Union Trans., v. 47, p. 192.

Bieler, B. H., and Wright, H. D., 1960, Primary mineralization of 

uranium-bearing "siliceous reef" veins in the Boulder 

batholith, Montana Part II, The veins: Econ. Geology, 

v. 55, p. 363-382.

Birch, Francis, 1954, Heat from radioactivity, Chapter 5 of 

Faul, Henry, ed., Nuclear geology: New York, John 

Wiley & Sons, Inc., p. 148-174.

 1965, Speculations on the earth's thermal history: 

Geol. Soc. America Bull., v. 76, p. 133-154.

Brown, Harrison, and Silver, L. T., 1956, The possibilities of 

obtaining long-range supplies of uranium, thorium, and other 

substances from igneous rocks, in Page, L. R., Stocking, 

H. E., and Smith, H. D., compilers, Contributions to the 

geology of uranium and thorium by the United States 

Geological Survey and Atomic Energy Commission for the 

United Nations International Conference on Peaceful Uses 

of Atomic Energy, Geneva, Switzerland, 1955: U.S. Geol. 

Survey Prof. Paper 300, p. 91-95.

Burfeind, W. J., 1967, Gravity investigation of the Tobacco 

Root Mountains, Jefferson Basin, Boulder batholith, and 

adjacent areas of southwestern Montana: Indiana Univ. 

Ph. D. dissert., 146 p.

Decker, E. R., 1966, Crustal heat flow in Colorado and New 

Mexico [abs.]: Am. Geophys. Union Trans., v. 47, p. 

180-181.

Doe, B. R., 1967, The bearing of lead isotope on the source of 

granitic magma: Jour. Petrology, v. 7, p. 1-33.

Doe, B. R., Tatsumoto, Mitsunobu, Delevaux, M. H., and Peterman, Z. E., 1967, Isotope-dilution determination of five 

elements in G-2 (granite), with a discussion of the analysis of 

lead, in Geological Survey research 1967: U.S. Geol. 

Survey Prof. Paper 575-B, p. B170-B177.

Doe, B. R., Tilling, R. I., Hedge, C. R., and Klepper, M. R., 

1968, Lead and strontium isotope studies of the Boulder 

batholith, southwestern Montana: Econ. Geology, v. 63, 

p. 884-906.

Gottfried, David, Moore, 'Roosevelt, and Caemmerer, Alice, 

1962, Thorium and uranium in some alkalic igneous rocks 

from Virginia and Texas, in Short papers in geology, 

hydrology, and topography: U.S. Geol. Survey Prof. 

Paper 450-B, p. B70-B72.

Gottfried, David, Moore, Roosevelt, and Campbell, Esma, 1963, 

Thorium and uranium in some volcanic rocks from the 

circum-Pacific province, in Short papers in geology, hydrology, and topography: U.S. Geol. Survey Prof. Paper 

450-E, p. E85-E89.

Gottfried, David, Greenland, L. Paul, and Campbell, E. Y., 

1968, Variation of Nb-Ta, Zr-Hf, Th-U, and K-Cs in two 

diabase-granophyre suites: Geochim. et Cosmochim. Acta, 

v. 32, p. 925-948.

Grimaldi, F. S., May, Irving, and Fletcher, M. H., 1952, U.S. 

Geological Survey fluorimetric methods of uranium analysis: 

U.S. Geol. Survey Circ. 199, 20 p.

Hamilton, E. I., 1966, The uranium content of soir^ international standards: Earth and Planetary Sci. Letters, v. 1, 

p. 317-318.

Heier, K. S., and Carter, J. L., 1964, Uranium, thcrium, and 

potassium contents in basic rocks and their bear'ng on the 

nature of the upper mantle, in Adams, J. A. S., ard Lowder, 

W. M., eds., The natural radiation environment: Chicago, 

Univ. Chicago Press, p. 63-85.

Heier, K. S., and Rogers, J. J. W., 1963, Radiometrfc determination of thorium, uranium, and potassium in basalts and 

in two magmatic differentiation series: Geochim. et Cosmochim. Acta, v. 27, p. 137-154.

Hurley, P. M., 1950, Distribution of radioactivity in granites 

and possible relation to helium age measurements: Geol. 

Soc. America Bull., v. 61, p. 1-8.

Klepper, M. R., Weeks, R. A., and Ruppel, E. T., 1957, Geology 

of the southern Elkhorn Mountains, Jefferson end Broadwater Counties, Montana: U.S. Geol. Survey F-of. Paper 

292, 82 p.

Knopf, Adolph, 1913, Ore deposits of the Helena mining region, 

Montana: U.S. Geol. Survey Bull. 527, 143 p.

 1957, The Boulder bathylith of Montana: Am. Jour. Sci., 

v. 255, p. 81-103. 

-1963, Geology of the northern part of the BouMer bathylith and adjacent area, Lewis and Clark and Jefferson 

Counties, Montana: U.S. Geol. Survey Misc. Geol. Inv. Map 

1-381, scale 1:48,000.

Eolbe, Peter, and Taylor, S. R., 1966a, Geochemical investigation of the granitic rocks of the Snowy Mountains area, 

New South Wales: Geol. Soc. Australia Jour., v. 13, p. 1-25. 

 1966b, Major and trace element relationships in granodiorites and granites from Australia and South Afrw. Contr. 

Mineralogy and Petrology, v. 12, p. 202-222.

Lachenbruch, A. H., Wollenberg, H. A., Greene, G. W., and 

Smith, A. R., 1966, Heat flow and heat production in the 

central Sierra Nevada, preliminary results [abs.]: Am. 

Geophys. Union Trans., v. 47, p. 179.

Lachenbruch, A. H., Marshall, B. V., and Sass, J. H., 1967, 

Geothermal studies in the western United States and the 

Arctic, MI United States Program for the Irternational 

Mantle Project, Progress Report 1967: WashinHon, D.C., 

Natl. Acad. Sci.-Natl. Research Council, p. 63-P4.

Larsen, E. S., Jr., 1948, Batholith and associated rocks of 

Corona, Elsinore, and San Luis Rey quadrangle*, southern 

California: Geol. Soc. America Mem. 29, 182 p.

Larsen, E. S., Jr., and Gottfried, David, 1961, Distribution of 

uranium in rocks and minerals of Mesozoic batholiths in 

Western United States: U.S. Geol. Survey Bull. 1070-C, 

p. 63-102.

Larsen, E. S., Jr., and Schmidt, R. G., 1958, A reconnaissance 

of the Idaho batholith and comparison with tl ? southern 

California batholith: U.S. Geol. Survey Bull. 1070-A, 33 p.

Larsen, E. S., 3d, 1957, Distribution of uranium in igneous 

complexes: U.S. Geol. Survey TEI-700, p. 249-253, issued 

by U.S. Atomic Energy Comm. Tech. Inf. Service, Oak 

Ridge, Tenn.

Larsen, E. S., 3d, and Gottfried, David, 1960, Uranium and 

thorium in selected suites of igneous rocks: Anr, Jour. Sci. 

(Bradley volume), v. 258-A, p. 151-169.
THORIUM, URANIUM, POTASSIUM, HEAT PRODUCTION, BOULDER BATHOLITH, MONT. E2'

Lee, W. H. K., and Uyeda, S., 1965, Review of heat-flow data, 

in Lee, W. H. K., ed., Terrestrial heat flow: Am. Geophys. 

Union Geophys. Mon. Ser. no. 8, Natl. Acad. Sci.-Natl. 

Research Council Pub. 1288, p. 87-190.

Levine, Harry, and Grimaldi, P. S., 1958, Determination of 

thorium in the parts per million range in rocks: Geochim. 

et Cosmochim. Acta, v. 14, p. 93-97.

Lonsdale, J. T., and Maxwell, R. A., 1949, Petrology of Big 

Bend National Park, Texas [abs.]: Geol. Soc. America 

Bull., v. 60, no. 12, pt. 2, p. 1906.

Lyons, J. B., 1944, Igneous rocks of the northern Big Belt Range, 

Montana: Geol. Soc. America Bull., v. 55, no. 4, p. 445-472.

 1964, Distribution of thorium and uranium in three 

early Paleozoic plutonic series of New Hampshire: U.S. 

Geol. Survey Bull. 1144-P, 43 p.

McCamy, Keith, and Meyer, R. P., 1964, A correlation* method 

of apparent velocity measurement: Jour. Geophys. Research, v. 69, p. 691-700.

MacDonald, G. J. F., 1964, Dependence of the surface heat flow 

on the radioactivity of the earth: Jour. Geophys. Research, 

v. 69, p. 2933-2946.

Mathews, W. H., 1957, Petrology of Quaternary volcanics of 

the Mount Garibaldi map-area, southwestern British 

Columbia: Am. Jour. Sci., v. 255, p. 400-415.

May, Irving, and Jenkins, L. B., 1965, Use of arsenazo III in 

determination of thorium in rocks and minerals, in Geological Survey research 1965: U.S. Geol. Survey Prof. 

Paper 525-D, p. D192-D195.

Meyer, R. P., Steinhart, J. S., and Bonini, W. E., 1961, Montana, 

1959, Chapter 9 in Explosion studies of continental structure: Carnegie Inst. Washington Pub. 622, p. 305-343.

Moore, J. G., 1959, The quartz diorite boundary line in the 

Western United States: Jour. Geology, v. 67, p. 198-210.

Morgan, J. W., and Heier, K. S., 1966, Uranium, thorium, and 

potassium in six U.S.G.S. standard rocks: Earth and 

Planetary Sci. Letters, v. 1, p. 158-160.

Neuerburg, G. J., Antweiler, J. C., and Bieler, B. H., 1956, 

Uranium content and teachability of some igneous rocks 

of the United States: U.S. Geol. Survey Prof. Paper 300, 

p. 55-64.

Peacock, M. A., 1931, Classification of igneous rock series: 

Jour. Geology, v. 39, p. 54-67.

Peterman, Z. E., Doe, B. R., and Bartel, Ardith, 1967, Data 

on the rock GSP-1 (granodiorite) and the isotope-dilution 

method of analysis for Rb and Sr, in Geological Survey 

research 1967: U.S. Geol. Survey Prof. Paper 575-B, p. 

B181-B186.

Phair, George, and Gottfried, David, 1964, The Colorado Front 

Range, Colorado, U.S.A., as a uranium and thorium 

province, in Adams, J. A. S., and Lowder, W. M., eds., 

The naturel radiation environment, Chicago, Univ. Chicago 

Press, p. 7-38.

Powers, H. A., 1932, The lavas of the Modoc Lava Bed quadrangle, California: Am. Mineralogist, v. 17, p. 253-294.

Prostka, H. J., 1966, Igneous geology of the Dry Mountain 

quadrangle, Jefferson County, Montana: U.S. Geol. Survey 

Bull. 1221-F, 21 p.

Ragland, P. C., Billings, G. K., and Adams, J. A. S., 1967, 

Chemical fractionation and its relationship to the distribution of thorium and uranium in a zoned granite batholith: Geochim. et Cosmochim. Acta, v. 21, p. 17-34.

Robinson, G. D., 1963, Geology of the Three Forks quadrangle, Montana: U.S. Geol. Survey Prof. Paper 37C, 

143 p.

Robinson, G. D., Klepper, M. R., and Obradovich, Johr1968, Overlapping plutonism, volcanism, and tectonism 

in the Boulder batholith region, western Montana, in 

Coats, R. R., Hay, R. L., and Anderson, C. A., eds, 

Studies in volcanology, Howel Williams Volume: Geol. 

Soc. America Mem. 116, p. 557-576.

Robinson, G. D., and Marvin, R. P., 1967, Upper Cretaceon 

volcanic glass from western Montana: Geol. Soc. America 

Bull., v. 78, p. 601-608.

Roy, R. P., and Blackwell, D. D., 1966, Heat flow in the Sierra 

Nevada and western Great Basin [abs.]: Am. Geophy 

Union Trans., v. 47, p. 179-180.

Ruppel, E. T., 1961, Reconnaissance geologic map of th^ 

Deer Lodge quadrangle, Powell, Deer Lodge, and Jefferson 

Counties, Montana: U.S. Geol. Survey Mineral Inv. 

Field Studies Map MF-174, scale 1:48,000.

 1963, Geology of the Basin quadrangle, Jefferson, Lewis

and Clark, and Powell Counties, Montana: U.S. Ged.

Survey Bull. 1151, 121 p. 

Schmidt, R. G., 1957, Petrology of the volcanic rocks [of Saipan,

Mariana Islands]: U.S. Geol. Survey Prof. Paper 280-P,

p. 127-175. 

Shapiro, Leonard, and Brannock, W. W., 1962, Rapid analysis

of silicate, carbonate, and phosphate rocks: U.S. Gee1 .

Survey Bull. 1144-A, 56 p. 

Shavrova, N. N., 1958, The content of radium and thorium

in lavas of the Klyuchevshii Group: Akad. Nauk SSSR

Lab Vulkanologii Byull. Vukanol. Sta., no. 27, p. 51-f 4

(in Russian).

 1961, The content of radium and thorium in the lav^s

of the Bezymyanny volcano: Akad. Nauk SSSR Lab.

Vulkanologii Byull. Vulkanol. Sta., no. 31, p. 31-38 (in

Russian). 

Shaw, D. M., 1967, U, Th and K in the Canadian Precambrten

shield and possible mantle compositions: Geochim. et

Cosmochim. Acta, v. 31, p. 1111-1113. 

Smedes, H. W., 1962, Lowland Creek Volcanics, an upp^r

Oligocene formation near Butte, Montana: Jour. Geology, 

v. 70, p. 255-266.

 1966a, Geology and igneous petrology of the northern 

Elkhorn Mountains, Jefferson, and Broadwater Countie«, 

Montana: U.S. Geol. Survey Prof. Paper 510, 116 p. 

-1966b, Preliminary geologic map of the Butte South

quadrangle, Montana: U.S. Geol. Survey open-file map. 

Smedes, H. W., and Thomas, H. H., 1965, Reassignment of the

Lowland Creek Volcanics to Eocene age: Jour. Geology,

v. 73, p. 508-509. 

Stark, J. T., 1963, Petrology of volcanic rocks of Guam: U.S.

Geol. Survey Prof. Paper 403-C, p. 1-32. 

Thayer, T. P., 1957, Some relations of later Tertiary volcanology

and structures in eastern Oregon: Internat. Geol. Congrefs,

20th, Mexico City, 1956, Vulcanologia del Cenozoico, Tomo

1, sec.l, p. 231-245. 

Tilling, R. I., 1964, Variation in modes and norms of a "honrv

geneous" pluton of the Boulder batholith, Montana, in

Geological Survey research 1964: U.S. Geol. Sunmy

Prof. Paper 501-D, p. D8-D13 [1965].
E22 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

Tilling, R. I., Klepper, M. R., and Obradovich, J. D., 1968, 

K-Ar ages and time span of emplacement of the Boulder 

batholith, Montana: Am. Jour. Sci., v. 266, p. 671-689.

Tilton, G. R., Patterson, Claire, Brown, Harrison, Inghram, 

Mark, Hayden, Richard, Hess, David, and Larsen, E. S., 

Jr., 1955, Isotopic composition and distribution of lead, 

uranium, and thorium in a Precambrian granite [Ontario]: 

Geol. Soc. America Bull., v. 66, p. 1131-1148.

Von Herzen, R. P., 1967, Surface heat flow and some implications 

for the mantle, in Gaskell, T. F., ed., The earth's mantle: 

London and New York, Academic Press, p. 197-230.

Verhoogen, John, 1956, Temperatures within the earth, chapter 

2 of volume 1 in Ahrens, L. H., Rankama, K., and Runcorn, 

S. K., eds., Physics and Chemistry of the earth, London, 

Pergamon Press, p. 17-43.

Wasserburg, G. J., MacDonald, G. J. F., Hoyle, Fred, and 

Fowler, W. A., 1964, Relative contributions of uranium, 

thorium, and potassium to heat production in the earth: 

Science, v. 143, p. 465-467.

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

The relationship between the petrology and th^ thorium 

and uranium contents of some granitic rocks: G^ochim. et 

Cosmochim. Acta, v. 17, p. 248-271.

Williams, Howel, 1932, Geology of the Lassen Volcani*? National 

Park, California: California Univ. Dept. Geol. Sci. Bull., 

v. 21, no. 8, p. 195-385.

Wollenberg, H. A., and Smith, A. R., 1964, Radioactivity and 

radiogenic heat in Sierra Nevada plutons: Jour. Geophys. 

Research, v. 69, p. 3471-3478.

 1968a, Radiogeologic studies in the central part of the 

Sierra Nevada batholith, California: Jour. Geophys. Research, v. 73, p. 1481-1495.

1968b, Radiogenic heat production in pre-batholithic

rocks of the central Sierra Nevada [abs.]: Am. Geophys. 

Union Trans., v. 49, no. 1, p. 332-333.

Wright, H. D., and Bieler, B. H., 1960, Primary mineralization 

of uranium-bearing "siliceous reef" veins in the Boulder 

batholith, Montana Part I, The host rocks: Econ. 

Geology, v. 55, p. 56-72.
TABLES 7-15
E24 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

TABLE 7. Distribution of thorium, uranium, and potassium in prebatholith volcanic rocks of the Boulder batholith region

[Thorium and uranium analyses by Esma Campbell, Roosevelt Moore, and Alice Caemmerer (using methods cited in text), unless otherwise noted. Analysis for major elements 

using rapid methods described by Shapiro and Brannock (1962): Elkhorn Mountains samples, by F. 8. Borris, J. M. Dowd, P. L. D. Elmore, H. F. PhiTfps, and K. E. 

White; Three Forks samples, by P. L. D. Elmore, 8. D. Botts, and M. D. Mack; Wolf Creek and Maudlow samples, by P. L. D. Elmore, 8. D. Botts, Iva^ Barlow, and 

Gillison Chloe]

Sample

Potassium 

(percent)

Thorium 

(ppm)

Uranium 

(ppm) 'FT* /IT

Weight percent

SiCh KsO NazO

CaO

CaO KjO+NatO

Elkhorn Mountains volcanic field >

52C-76a............

52C-84a. _-...._...

52C-93.. ......... .

52C-95.. ...... .

52C-97.. ....... ...

52C-98.. ..........

52C-99- .......

52C-«8c.. .........

52C-108.- - ....

52C-111-. .........

Average .......

16.................

16a... ..............

192................

196................

140................

12.................

334................

339................

Average __ .

5.0 

1.8 

1.7 

3.2 

2.6 

3.6 

2.6 

1.7 

2.0 

2.0

2.6

2.6

1.1

2.8 

2.3

2.5 

2.6 

2.6

2.4

3.8 

18 

2.5 

8.9 

8.8 

4.9 

5.4 

8.9 

8.8 

8.8

6.6

114 

(14.9, 13.8) 

»16.7 

2.7 

(2.6, 2.8) 

3.1 

5.8 

(5.5, 6.1) 

9.3 

3.8 

3.1 

(3.0, 3.2)

6.0

(2.5, 

(1.0, 

(0.74, 

(3.0, 

(2.3, 

(1.8, 

(1.8, 

(2.3, 

(3.1, 

(2.5,

2.5 

2.5) 

1.0 

1.0) 

0.71 

0.68) 

2.9 

2.7) 

2.3 

2.3) 

1.8 

1.9) 

1.8 

1.7) 

2.3 

2.3) 

3.0 

2.8) 

2.6 

2.6)

2.1

7.1 

(7.0, 7.2) 

*4.59 

.9 

(1.0, 0.8) 

1.6 

1.8

6.0 

2.4 

.8 

(1.2, 0.5)

2.9

1.5 

4.8 

3.5 

3.1 

3.8 

2.6 

3.0 

3.9 

2.9 

3.4

3.2

2.0 

3.6

3.0

1.9 

3.2

1.6 

1.6 

3.9

2.4

54.5 

51.6 

49.8 

616 

62.5 

58.6 

57.7 

62.5 

57.2 

62.8

68.2

63.6

59.4

62.1 

68.5

57.9 

70.2 

71.4

63.3

6.0 

2.2 

2.0 

5.7 

5.2 

5.0 

3.2 

2.0 

2.4 

2.4

3.6

Three Forks*

3.1

1.3

3.4 

2.8

3.0 

3.2 

3.1

2.8

3.4 

2.4 

2.2 

3.8 

3.2 

13 

2.5 

2.0 

1.7 

2.2

2.8

ireaJ

3.9

3.9

3.5 

3.3

3.7 

4.2 

4.0

3.8

6.0 

8.7 

9.5 

1.5 

2.4 

2.3 

6.4 

5.8 

8.0 

4.0

5.5

3.0

6.2

12 

6.1

5.2 

1.7 

1.6

4.0

0.49 

1.89 

2.26 

.16 

.29 

.25 

1.12 

1.45 

1.95 

.87

1.07

0.43

1.19 

.61

too

.78 

.23 

.23

.64

Andesite flow.

"Qabbro", intrusive equivalent of Elkhorn 

Mountains Volcanics. 

Basalt flow.

Trachyte flow. 

Do. 

Do. 

Andesite flow. 

Dacite welded toff. 

Andesite flow. 

Do.

Rhyodacite perlite (70 percent glars).

Glass fraction from sample 16. 

Andesite flow.

Do. 

Do.

Latite. « 

\Dacite laccolith correlative with latite (sample 

/ 12).«

Wolf Creek area «

WC-59-20.. .......

WC-60-23.........

WC-60-37... ......

WC-59-14.........

Average ___

6.0

10 

.7 

3.4

3.5

12.0

6.8 

(6.3, 7.3) 

16.9 

(17.1, 16.7) 

30.9

16.6

4.0

2.0 

3.3 

5.6

3.7

3.0

3.4 

5.1 

5.5

4.2

59.0

57.3 

65.8 

76.1

64.6

7.2

4.8 

.80 

4.1

4.2

3.9

3.4 

3.0 

11

3.6

3.0

18 

16 

.31

3.2

0.27

.59 

1.21 

.04

.53

Latite flow; upper part of Two Medicine Formation.

Dacite flow; lower part of Two Medicine Formation. 

Quartz latite, ashflow unit; lower part of Two 

Medicine Formation. 

Rhyolite dike or sill; assumed to be Elkhorn 

Mountains Volcanics equivalent.

Maudlow area

35-59.............. 0.5 17.5

(2.6,

2.8 

3.0)

6.2 616 0.68 1.2 5.6 3.11 Glassy welded tuff, described by Robinson and 

Marvin (1967).

i Geologic information regarding samples from R. W. Chapman (written commun., 1956).

* Geologic information regarding samples from Robinson (1963).

* Isotope dilution determinations by Brace R. Doe, U.S. Geological Survey.

4 Intrusive equivalents of the Elkhorn Mountains Volcanics.

1 Geologic Information regarding samples from R. G. Schmidt (oral commun., 1968).
THORIUM, URANIUM, POTASSIUM, HEAT PRODUCTION, BOULDER BATHOLITH, MONT. 

TABLE 8. Distribution of thorium, uranium, and potassium in rocks of the Boulder batholith

E25

[Rocks grouped according to map units (fig. 2) from oldest to youngest (except for satellitic plutons); letters in parentheses refer to map units. Thorium and uranium analy^s 

by Esma Campbell, Roosevelt Moore, and Alice Caemmerer (using methods cited in text), unless otherwise noted. Analysts for major elements, l-8,_using rapid methods 

described by Shapiro and Brannock (1962); 9,10, using standard methods: 1, F. S. Boms, J. M. Dowd, P. L. D. Elmore, H. F. Phillips, and K. E. White; 2, P. L. D. 

Elmore, S. D. Botts, Gillison Chloe, Lowell Artis, and Hezekiah Smith; 3, P. L. D. Elmore, S. D. Botts, and M. D. Mack; 4, P. L. D. Elmore, S. D. Botts, J. L. Glenn, 

Gillison Chloe, Lowell Artis, and Hezekiah Smith; 5, P. L. D. Elmore, I. H. Barlow, S. D. Botts, and Gillison Chloe; 6, P. L. D. Elmore and E. E. White; 7. P. L. D. 

Elmore, E. E. White, and S. D. Botts; 8, P. L. D. Elmore, S. D. Botts, Lowell Artis, Gillison Chloe, J. L. Glenn, Hezekiah Smith, and James Kelsey; 9, Elaine L. 

Munson; 10, J. J. Engel, in Enopf (1957)]

Sample 

No.

Potassium 

(percent)

Thorium 

(ppm)

Uranium 

(ppm) Th/U -

Weight percent

SiOj KjO NazO

CaO

CaO KiO+NajO

Analysts 

Remarks for majrnr 

elements

Mafic rocks (m)

S1419.. ......

63E-350 ... ...

4S-C-1.- .....

4T-360- ... ...

Average.....

2.6 

2.3 

2.7 

3.1

2.7

5.6 

(5.5, 5.7) 

5.9

10.7 

(10.0, 11.4) 

2.7 

(2.7, 2.7)

6.2

1.7 

2.3

1.6 

(1.4, 1.7, 1.8) 

0.4 

(0.5, 0.4)

1.5

3.3

2.6 

6.7 

6.7

4.8

54.5 

56.5 

57.9 

57.2

56.5

3.2 

2.8 

3.3 

3.7

3.2

2.2 

2.7 

2.6 

3.9

2.8

6.8 

6.0 

6.6 

6.4

6.4

1.26 

L09 

1.12 

.84

Syenogabbro (calcic melamonzonite of Smedes. 

1966a, table 2, No. 9). 

Syenogabbro (Ringing Rocks stock, Prostka, 

1966). 

Composite of eight samples (Smedes, 1966a, 

table 2, No. 8).

5

4 

6

4

1.08

Granodiorite (ug, re, bp) 1

53C-140- ... .

4T-349- ... ...

3T-500- ... ...

53C-191.- ... .

5T-60.. .........

Average 

(ug, bp)

53C-163-- ......

B8C-166 ......

53O-168- ....

2T-1057- ....

2T-1065 ......

2T-1080-.-. ..

2T-1093

Average 

(re)

3.3

2.7 

3.4

2.5 

2.0

2.8

2.1 

2.6 

2.2 

2.3

22

2.6 

3.6

2.5

16.9

9.3 

10.8 

(10.9, 10.6) 

9.2

8.8 

(9.3, 8.3)

11.0

5.4 

(5.7, 5.0) 

6.6 

(6.1, 7.1) 

6.6

7.4 

(7.4, 7.7, 

7.0, 7.4)

(8,1, 8.J

9.3 

(8.9, 9.7) 

8.0 

(8.1, 7.9)

7.3

5.7 

(5.9, 5.5) 

1.7 

2.4

3.3 

(3.4, 3.2) 

3.9

3.4

1.2 

(1.3, 1.2) 

1.2 

(L4, 1.1) 

1.6 

(1.7, 1.6) 

0.8 

(0.8, 0.7

1.2 

(LI, 1.3)

2.7

1.7 

(1.8, 1.6)

1.5

3.0

5.5 

4.5

2.8 

2.2

3.6

4.5 

5.5 

4.1 

9.2

6.8

3.4 

4.7

*4,8

63.2

61.14 

63.0

61.0 

62.1

62.1

69.6 

66.0 

62.4 

68.6

64.6

63.6 

65.6

65.8

4.0

3.34 

4.1

3.0 

2.4

3.4

2.5 

3.1 

2.6 

2.8

2.6

3.1 

4.3

3.0

2.5

2.78 

2.8

2.6 

2.9

2.7

3.6 

3.3 

3.3 

3.6

3.6

3.4 

3.6

3.5

4.6

5.51 

4.4

5.8 

6.0

5.3

3.4 

4.6 

5.7 

3.8

4.8

4.5 

3.3

4.3

0.71 ) ( 1 1 Mafic granodiorite; samples from UnionviQe 1 

.90 | Granodiorite. 1 10 

.64 J I 4

1-04 1 Mafic granodiorite; samples from Burton Park J 

j 13 j pluton (Smedes, 1966b). 1 4

.88

.56 

.72 

.97 

.59

.77

.69 

.42

Felsic granodiorite; samples from Rader Creek 

pluton (Tilling, 1964).

1

1 

1 

2

2

2 

2

.67

Bntte Quartz Moraonlte (bqm)

52C-10a ... 

54C-248.- ... .

52C-52b ---.- 

52C-60... . ...

52C-65- ... ...

53C-205. . ....

63C-209

52C-114.. ... .

63C-202... ...

56E-420 ... ...

56E-494 ......

6K-306.... ...

DDH-B-3 

52C-13 .... 

53C-149- ... -

63C-150-. ...

3T-273.. ...... ..

Average.....

3.5 

1.8 

3.5 

3.2 

3.3 

3.3 

3.4 

3.5 

3.3 

3.6 

3.7 

3.4

3.4 

3.2

3.3 

3.3 

3.1

3.4

13.0 

(12.6,13.3) 

7.9

19.0 

18.8 

15.2

16.2 

(16.3,16.0) 

16.2

17.9 

15.6

14.6 

(15.0,14.2) 

15.4 

(15.3,15.6) 

11.8 

(11.2,12.4) 

24.9 

15.5

16.9

15.6 

(15.6,15.5) 

18.0 

(17.3,18.7) 

»16.14

16.2

2.9 

(3.0,2.8) 

3.2 

(3.3,3.1)

(7.2,7io) 

5.1 

(5.2,5.0) 

2.4 

(2.5,2.4) 

5.1 

(5.2,4.9) 

3.8 

(3.7,3.9) 

1.6 

(1.7,1.6) 

5.2 

(4.9,5.6,5.1)

(4.2,4,0) 

3.2 

(3.2,3.2) 

3.3 

(3. 1, 3. 5) 

6.4 

3.2 

(3.3,3.2) 

4.5 

(3.9,5.0,4.6) 

3.6 

(3.3,3.8) 

4,6

'4.32

4.0

4,5 

2.5 

2.7 

3.7 

6.3 

3.2 

4.3 

11.2 

3.0 

3.6 

4,8 

3.6

3.8 

4.8

3.8 

4.3 

3.9 

3.7

«4.0

59.8 

50.6 

65.3 

64.0 

62.5 

63.5 

64.3 

63.0 

63.8 

64.8 

65.3 

65.4

66.0 

64.8

65.0 

66.6 

65.49

64.6

4.2 

2.2 

4.2 

3.9 

4.0 

4.0 

4.1 

4.2 

4.0 

4.3 

4.5 

4.1

4.1 

3.9

4.0 

4.0 

3.66

4.1

3.0 

3.1 

3.0 

2.9 

2.8 

3.0 

2.9 

2.9 

3.0 

3.0 

2.7 

2.9

2.9 

3.1

2.8 

3.0 

2.80

2.9

5.1 

7.2 

3.2 

4.2 

4.6 

4.4 

4.1 

4.3 

4.2 

4.2 

3.8 

4.0

4.0 

4.4

4.3 

3.8 

4.29

4.1

0.71 

1.36 

.44 

.62 

.68 

.63 

.59 

.61 

.60' 

.58 

.63 

.57

.56 

.63

.63 

.54 

.66

Strongly foliated xenolith-rich border fades; 

 these two samples are not plotted in figures 

and are excluded from averages.

Coarse-grained equigranular to slightly porphyritic varieties with E-feldspar megacrysts.

Coarse-grained strongly porphyritic varieties 

with E-feldspar megacrysts; 3T-273 is the 

"type" Clancy Granodiorite; DDH-B-3 is 

average of 19 samples from drill hole (table 14) .

1

1

1 

1 

1 

1 

1 

1 

7 

7 

7

1

1 

1 

10

.59

See footnotes at end of table.
E26 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

TABLE 8. Distribution of thorium, uranium, and potassium in rocks of the Boulder batholith Continued

Sample 

No.

Potassium 

(percent)

Thorium 

(ppm)

Uranium 

(ppm) Th/U -

Weight percent

SiOz KzO NfeO CaO 1

CaO

fcO+NazO

Remarks

Analysts 

for major 

elements

Silicic fades of Butte Quartz Monzonlte (pr, h)

62C-113a

53C-203- 

530-206. 

2T-534... ..

62C-45. ......

IK-241 

Average.. 

3.5

11 

3.6 

3.8 

3.3 

3.5

3.6

18.3 

(18.2,18.1, 

18.3,18.6) 

23.0

19.0 

38.6 

119 

20.1

22.3

12.1 

(12.0,12.2)

13 

(13,13) 

3.4 

(3.2,3.6) 

18 

(18,19) 

2.6 

(2.6,2.6) 

8.3

6.9

1.5

5.3 

6.6 

7.9 

5.7 

2.4

17

68.0

67.3 

70.9 

72.3 

68.4 

71.5

69.7

12

19 

14 

16 

10 

12

14

3.1

2.9 

3.4 

3.0 

3.4 

2.9

3.1

3.2

2.9 

2.3 

2.4 

3.2 

2.9

2.8

0.70

.37 

.31 

.32, 

.43 

.41

.42

Shown as part of the Butte Quartz Monzonita , (bqm) hi figure 2.

Pulpit Rock pluton (pr) (fig. 2) 

1

1

1 

2 

1

5

Alaskltes(a)

62C-8-.. . ....

52C-15 ...

54C-249.- 

6K-445a ......

62KOO ... ... ..

Average. ..

6T-29a

15 

18 

12 

3.9 

19

15

14

26 

34 

40 

42

39.6 

(38.9,40.2)

36.3

17.6

14 

(15,13) 

19 

(6.2,17,19) 

7.5 

(6.2,9.3) 

20 

(20,20) 

9.0

9.2

2.6

6.9 

6.9 

5.3 

2.1 

14

19

6.8

79.2 

76.7 

76.2 

78.0 

78.4

77.1

73.2

5.4 

5.8 

5.0 

17 

5.9

6.4

5.3

3.0 

2.2 

3.0 

3.2 

2.3

2.7

3.1

0.36 

.81 

.80 

.85 

.93

.75

1.1

Leucocratic rocks (d, he,

53C-lMa- .......

W-21 ... .....

2T-275- ..

63C-207-- ....

520-37. 

53C-204- ....

IK-633 

2T-797 ... ... 

66TB-1. ........

60S-C-8. .....

1753 

Average. .

2.4 

2.8

3.0 

3.2

2.8 

2.8 

3.0 

2.6 

3.0

3.2

2.8 

3.4

2.9

12.7

12.8 

(13.6, 12.1) 

212 

7.6 

(7.5,7.8) 

10.4

8.1 

11.8

17.3 

(16.7,17.9) 

17.3

19.5 

(18.6,20.4) 

16.2 

30.7 

(30.5,30.9)

16.7

2.3 

(2. 1, 2. 5) 

2.1

3.7 

2.4 

(2.5,2.6) 

1.6 

(1.7,1.2) 

2.0 

(2.1,2.0) 

6.2 

(6.3,6.0) 

5.0 

(5.0,5.0) 

8.8 

(8.6,8.9)

12 

(10,15) 

3.2 

8.0

11

5.6 

6.1

6.5 

3.2

6.5 

10 

1.9 

3.5 

2.0

16

5.1 

3.8

14

70.4 

70.4

70.1 

71.1

71.2 

70.8 

68.0 

67.4 

70.8

65.18

612 

70.0

69.1

2.9 3.9 

3.4 10

3.6 3.6 

3.9 3.8

3.4 12 

3.4 12 

3.6 3.2 

3.2 3.7 

3.6 3.8

3.75 3.09

3.4 3.3 

11 3.1

3.5 3.6

2.3 

2.6

2.9 

2.1

2.4 

2.4 

3.2 

3.7 

2.2

4.14

15 

2.9

2.9

0.04 

.11 

.10 

.17 

.11

.11

.13

c)

0.34 

.35

.40 

.27

.33 

.33 

.47 

.54 

.30

.60

.67 

.40.

.42

Alaskite . . .

Alaskite.. ......................................

Alaskite

Alaskite.- __ . ....................

Alaskite. ..................... ...........

Granite porphyry (not shown in fig. 2) ; iis 

relationship to alaskite is not known, but it 

is grouped with alaskite because of chemicM 

similarity.

Rocks lithologically similar to those of tin 

Donald pluton (not shown hi fig. 2).

Hell Canyon pluton (he) (fig. 2) ....... 

Sample from Tobacco Root batholith (across tin 

Jefferson River valley from the Hell Canyon 

pluton) lithologically similar to samples IK633 and 2T-797.

 Climax Gulch pluton (c) (fig. 2).. . .... .

1

1 

1 

7 

2

8

1 

2

2 

1

1 

1

2 

3

[ 

I S

Satellitic plutona (s)

211 ..........

216 

224 

62C-116-- ...

M3-205.-. _ 

M6-208. ......

Average .....

2.3 

2.3

10 

3.6

'2.0 

U.6

2.6

16 

(13,18) 

10 

(11,3.9) 

9.8 

11.1

»2.6 '3.6

5.9

0.8

.7

1.7 

2.3 

(2.3,2.3) 

 1.6 LI

1.4

5.7 

5.7

5.8 

18

1.5 

3.4

15

58.4 

59.7

65.1 

65.2

ND 

ND

62.1

2.8 

2.8

18 

12

2.4 

1.9

3.2

3.2 

3.4

11 

3.2

ND 

ND

3.5

6.2 

5.8

3.2 

3.6

ND .

ND .

17

1.03 

.94

.36 

.49

.70

Kgd (granodiorite undivided) of Knopf (1963) 

IMarysville stock; data from Whitfield, Rogerf , 

I and Adams (1959).

1 3

3 

1

' Age relations between the granodiorite units are not known because these rocks do not occur in contact with one another.

2 Excluding the anomalously high value of 9.2 for sample 2T-1057.

3 Isotope dilntion determination by Brace R. Doe, U.S. Geol. Survey.

* Excluding the anomalously high valne of 11.2 for sample 52C-114.

 Thorium, uranium, and potassium determined by gamma-ray spectrometry; data from Whitfield, Rogers, and Adams (1959).
THORIUM, URANIUM, POTASSIUM, HEAT PRODUCTION, BOULDER BATHOLITH, MONT. E27

TABLE 9. Distribution of thorium, uranium, and potassium in mafic inclusions in some rocks of the Boulder batholith

(Thorium and uranium analyses by Alice Caemmerer and Roosevelt Moore, using methods cited hi text. Major element analyses by F. 8. Borris, J. M. Dowd, P. L. D. Elmor % 

H. F. Phillips, and K. E. White, using rapid methods described by Shapiro and Brannock (1962). Remarks from R. W. Chapman (written commun., 1956)]

Sample

53C-120b.- ...... .

53C-160a.-.. .....

53C-160b.. .

53C-176-. ...........

53C-177a... 

83C-177b.. .......

Average .........

Potassium 

(percent)

4.6 

3.6 

1.9 

.7 

1.2 

1.1

2.2

Thorium 

(ppm)

11.7

ia?

7.9 

2.7 

6.1

1.9 

(2.0,1.8)

6.7

Uranium 

(ppm) '.

4.2 

(4.4,4.1) 

5.9 

(6.7,6.1) 

3.2 

(3.1,3.4)

(1.1,1:1) 

CLT.L;

(0.8, a 9)

2.8

rh/u -

2.8 

1.8 

2.5 

2.5 

3.2 

2.4

2.5

Weight percent

8102

58.8 

66.8 

66.9 

46.0 

64.6 

61.8

64.0

K20 NajO

6.6 

4.2 

2.3 

.84 

1.6 

1.3

2.6

2.7 

3.6 

3.7 

1.6 

2.9 

3.3

3.0

CaO

CaO KaO+NajO

6.4 

6.4 

6.3 

9.6 

7.6 

8.3

7.1

Remarks

0.651

. 69 Inost rock is Butte Quartz Mon- 

( zonite. 

1.06 J

3.941

1. 73 [Host rock is satellitlc pluton of 

"dioritic" composition. 

1.81 J

1.64

TABLE 10. Distribution of thorium, uranium, and potassium in the postbatholith Lowland Creek Volcanics (early Eocene)

[Thorium and uranium analyses by Roosevelt Moore, Esma Campbell, and Alice Caemmerer, using methods cited in text. Analysts for major elements, using rapid methods 

described by Shapiro and Brannock (1962): 1, H. F. Phillips, K. E. White, F. S. Borris, P/L. D. Elmore; 2, P. L. D. Elmore, I. H. Barlow, S. D. Botts; 3, P. L. I). 

Elmore, S. D. Botts, Gillison Chloe, Lowell Artis, and Hezeklah Smith; 4, P. L. D. Elmore, S. D. Botts, and M. D. Mack; 6, H. F. Phillips, K. E. White, and J. 1*. 

Dowd]

Potassium 

Sample (percent)

78-110.........

78-111.........

78-112.........

SI-417 __ . _ .

68-362.........

52C-64 _ .....

52C-66.. ......

52C-86 L......

52C-72 __ ....

52C-104.......

719.. . ...

Average 

1.9 

4.4 

3.6 

2.1 

3.2 

2.2 

2.8 

2.0

2.9 

3.7 

ND

2.9

Thorium 

(ppm)

6.5 

(6.1,6.9) 

18.8 

(19.2,18.3) 

20.2 

(20.0,20.6) 

4.0 

(4.6,3.3) 

6.3 

(7.0,6.6) 

8.9

9.0 

6.0

7.9 

8.8

4.0 

(3.7,4.3)

9.0

Uranium 

(ppm) '

2.9

1.6 

(1.4,1.6) 

4.0

.8 

1.9

1.8 

(1.9,1.8,1.8) 

2.4 

(2.6,2.4) 

2.0

(il«

(3.2,3.9) 

2.6 

(2.6,2.5) 

4.5

2.5

Th/U -

2.2 

12.5 

5.1 

6.0 

3.3 

6.0 

3.8 

2.5

2.2 

3.4 

.9

43

Weight percent

SiO3

63.4 

70.0

71.6

69.1 

70.5 

73.1 

67.9 

61.0

68.5 

67.6 

ND

68.3

K20 NasO

2.3 

6.3 

4.3 

2.5 

3.8 

2.6 

3.4 

2.4

3.5 

4.5 

ND

3.5

4.2 

2.8 

3.8 

4.3 

3.6 

3.4 

2.9 

3.3

2.8 

2.4 

ND

3.4

CaO

CaO K20+N820

4.2 

1.7 

1.5 

2.9 

2.2 

2.4 

2.3 

4.8

2.6 

2.6 

ND

2.7

0.66 

.21 

.16 

.43 

.30 

.40 

.37 

.84

.41 

.38 

ND

.42

AnalystsRemarks for major 

elements

Quartz latite porphyry

Rhyolite vitrophyre, very near quartz latite..

Quartz latite lava

Quartz latite lava

Andesite dike cutting Kgd (granodiorite undivided) of KnopfTl963).

Rhyolite dike, cutting alteration halo in Butte 

Quartz Monzonite, 4,100-foot level, Steward 

mine, Butte district.

2 

2 

2 

3 

4 

1 

5 

1

1

1

1 The assignment of this sample to the Lowland Creek Volcanics is arbitrary, based on compositional similarity.

TABLE 11. Distribution of thorium, uranium, and potassium in the postbatholith igneous rocks of probable early Tertiary age in the

Boulder batholith region

[Thorium and uranium analyses by Esma Campbell and Roosevelt Moore, using methods cited in text. Analysts for major elements, using rapid methods described by Shapi'o 

and Brannock (1962): Three Forks sample, P. L. D. Elmore, S. D. Botts, and M. D. Mack; Wolf Creek samples, P. L. D. Elmore, S. D. Botts, I. H. Barlow, and Gillison 

Chloe]

Potassium Thorium 

Sample (percent) (ppm)

Uranium 

(ppm) '.

Weight percent CaO

SiOa KiO N82O CaO KjO+NajO

Wolf Creek area

WC-60-5.. 

WC-60-15.. .

2.6 2.1 

(1.9,2.3)

2.2 4.1 

(4.0,4.2)

0.4 

(a 6, 0.4)

as

(0.8,0.8)

6.3 50.8 3.1 

5.1 52.8 2.7

as 7.0

4.8 5.1

1.10 Syenogabbro or trachybasalt which intrudes 

Two Medicine Formation (R. G. Schmic't., 

oral commun. 1968). 

.68 Hornblende monzonite dike intruding Ac" el 

Mountain Volcanics of Lyons (1944) (R. G. 

Schmidt, oral commun, 1968).

Three Forks area

326. 

Average ..

1.8 7.9 

(7.9,7.9)

2. 2 4. 7

2.1

1.1

3.8 54.5 2.2

4. 7 52. 7 2. 7

3.0 6.5

3.7 6.2

1. 25 Basalt which intrudes Tertiary rocks (Robinson, 

1963).

2.93
E28 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

TABLE 12. Distribution of thorium, uranium, and potassium in post-Lowland Creek volcanic rocks (Miocene or Pliocene)

[Thorium and uranium by Esma Campbell, Roosevelt Moore, and Alice Caemmerer, using methods cited in text. Analysts for major elements, using rapid met! ods described 

by Shapiro and Brannock (1962): 1, F. S. Borris, J. M. Dowd, P. L. D. Elmore, H. F. Phillips, and K. E. White; 2, P. L. D. Elmore, S. D. Botts, Lowel" Artis, James 

Kelsey, Gillison Chloe, J. L. Glenn, and Hezekiah Smith]

Potassium Thorium TJranit 

Sample (percent) (ppm) (ppm

4T-505-. ...

52C-1... ..

52C-20b

52C-20C _ ......

52C-79a 

52O80 .

52C-8U. ........

52C-83a... ...

52C-83b

53C-135 ...

Average .....

4.6 

3.3 (17' 1'

0 O

6.6

4.2 ^ 

3.3 

4.2

30 (20>4> 

o. U

2.3

2.8

3.8 

(30.7,

3.5

17.1 if"

34.2 <" * 

34.4) (7.8, 

42 

(18.5, 

10.4 

(2.5, 

18.8 

17.1) 

8.8 

(2.4, 

3.2 

(2.3, 

9.6 

(2.2, 

31.3 

31.9)

21.9

im Weight percent CaO Ant

SiOa KjO NasO CaO KjO+NasO eleu

4.4 3.9 72.1 5.6 2.1 0.88 0.14 Rhyolite lava.

11.6 4.2 78.0 4.0 4.0 .34 .04 Por phyritic soda rhyoUte from small intrusiv' 

11.8) plug. 8.5 4.0 75.6 4.0 2.4 .44 .07 Aphanitic rock near center of dike; quart'' 

9.3) latite very near rhyolite (Smedes, 1966a>. 

18.0 2.3 71.6 5.0 3.4 .05 .01 Rhyolite pitch stone near margin of dib* 

17.6) (Smedes, 1966a). 2.6 4.0 67.6 4.0 3.4 2.4 .32 Quartz latite lava..... __ .................. ...

2.6) 

2.6 7.2 78.0 5.0 2.2 .45 .05 Rhyolite lava.. ........................

2.4 3.7 68.0 3.6 4.2 2.6 .33 Quartz latite lava... ...................

2.3) 

2.2 1.5 66.2 2.8 4.2 3.2 .46 Quartz latite lava, aphanitic and perlitic .... ..

2.2) 

2.1 4.6 71.6 3.4 3.6 2.4 .34 Quartz latite lava, vesicular...................

2.0) 

6.2 5.0 76.0 4.6 4.0 .30 .03 Soda rhyolite dike.. . .............. .......

6.-1 4.0 72.5 4.2 3.4 1.3 0.18

ilysts 

najor 

aents

2 

1 

1

1 

1

1 

1 

1

1 

1

TABLE 13. Distribution of thorium and uranium in the Butte Quartz Monzonite from underground workings in the Butte district, Montana

[Samples collected by E. C. Robertson, U.S. Geol. Survey. Thorium and uranium analyses by Esma Campbell and 

Roosevelt Moore, using methods cited in text)

Sample

720 __ .....

733 __

725

726 

727-2..... 

717.... 

718. ..

732.... 

731.. 

723... 

722-2.... 

722-3... 

729.... 

800. 

Mine Approximate Thorium Uranium Th/U 

depth (feet) (ppm) (ppm)

Steward...... __ ................. 3,400 13.2 4.9 2.7

(13.0,13.4) 

..-..do................... .......... 3,800 14.8 2.2 6.7

(15.8,13.9) 

.....do. __.....-.... .... . 3,900 15.6 4.5 3.5

.....do..... 4,000 12.1 3.3 3.7

.....do.. . . 4,000 18.6 4.5 4.1

(18.9,18.3) 

.....do __ .... .... ... ........ . - 4,100 25.8 5.6 4.6

.....do..-. .. 4,100 10.2 4.6 2.2

. .do..- 4,200 23.3 3.8 6.1

 do. _ ........ .. 4,400 18.2 3.9 4.7

Mt. Con..... . .. . 4,200 19.3 8.8 2.2

. .do 5,000 18.0 2.9 6.2

(17.8,18.1) 

 do..-. 5,000 13.5 2.4 5.6

Leonard........... ................ 2,000 22.1 6.5 3.4

Kelley- ... ..... .... - 4,600 15.4 3.7 4.2

(14.9,15.8)

Average. 17.1 4.4 4.3
THORIUM, URANIUM, POTASSIUM, HEAT PRODUCTION, BOULDER BATHOLITH, MONT.

TABLE 14. Distribution of thorium, uranium, and potassium in Butte Quartz Monzonite samples from a drill hole

(DDH-B-S) for which heat flow has been measured

[Samples provided by D. D. Blackwell, Southern Methodist Univ. and E. C. Robertson, U. S. Geol. Survey. Specific gravity: Determined by 

specific-gravity balance, using solid core segments. This report: Potassium analyses (atomic-absorption determinations) by P. L. D. 

Elmore, Lowell Artls, S. D. Botts, Oillison Chloe, J. L. Glean, James Kelsey, and Hezekiah Smith; thorium and uranium analyses by 

Roosevelt Moore. Previous analysis: D. D. Blackwell (written commun., 1968); analyses (gamma-ray spectrometric determinations on 

solid core segments) by Gordon McKay, Bice Univ.]

Sample No. and 

depth (feet)

850. _ . _ .......

950......- .....

1050....-. ...

1150. ...........

1350 .

I860. __.. ... .

2150 .

2250.. .

2450. .,

2550..... .....

2660 .... ......

2750. .

2850 .

2950 .

3050».. ..... .

3160-3200 »-. .

3450-3500»._......

3550-3600 «-. ...

3950-3995 »-.. ..

Average ......

This report

gravity Potassium 

(percent)

2.68

2.72

2.68

2.69

2.70

2 72

2.71

2.71

2.70

2.69

2.72

2.74

2.67

2.70

»2.67

»2.71

»2.75

*2.71

»2.68

2.70

3.1 

3.4 

3.4 

3.4 

3.6 

3.5 

3.4 

3.7 

3.3 

2.8

3.6

3.4

3.0

3.5 

3.2 

3.6 

3.6 

3.7

3.9

3.4

Thorium 

(ppm)

32.4 

25.9 

249 

240 

26.3 

20.0 

26.2 

240 

240 

247 

(248,246) 

17.2 

(16.7,17.6) 

19.5 

16.2 

(16.8,16.7) 

25.2 

(25.2,25.3) 

20.5 

(20.9,20.1) 

12.8 

(12.4,13.2) 

18.4 

(17.8,19.1) 

20.6 

(21.0,2aO, 

20.7) 

2L6 

(21.0,22.2)

22.8

Previous analysis

Uranium Potassium Thorium Uranium 

(ppm) Th/U (percent) (ppm) (ppm) Th/U

8.0 

8.2 

48 

3.8 

42 

6.0 

6.8 

7.6 

8.2 

6.2

4.8

6.8 

46

11.8

6.6 

(6.4,6.8) 

3.5 

(3.0,3.4,40) 

6.0 

(6.4,6.6) 

7.1 

(7.0,7.2)

6.4 

(6.4,6.2)

6.3

40 

3 2 __ .. .

6.2 ... 

6.3 .. 

6.0 

a a

5 0

3.2 

2.9 

40 

3.6 

3.4 

3.5 

2.1 _ .. . __ .,

3.1 41 23.8 

3.7 45 19.7 

3.1 3.9 22.3 

2.9 42 20.7

3.3 44 240

3.7 ... 

8.0 3.0 

6.4 3.6 

6.6 3.4 

6.5 3.2

6.6 43

i Composite samples of three pieces of core collected at the depth or between the depths indicated by sample number. 

< Average of the three chips in composite.

NOTE: The potassium determinations by gamma-ray spectrometry are systematically higher than those by atomic absorption, by as much as 

30 percent. The reason for this lack of agreement is not clear but may perhaps be the different form of the samples: the gamma-ray determinations were on composites of actual drill-core segments (that is, sample was not powdered), whereas the atomic-absorption determinations were on powdered sample material representing approximately 1 inch of each of the three (1.5-inch diameter) core segments making 

up the original composite samples. Although the agreement between thorium and uranium is much better, the difference in sample form 

may also account for some of the discrepancy between our data and the Bice Univ. data.

TABLE 15. Distribution of thorium, uranium, and potassium in a single stock of Woodson Mountain Granodiorite, Southern California

batholith

'Thorium and uranium analyses by Roosevelt Moore, Esma Campbell, and L. B. Jenkins; major-element analyses by P. L. D. Elmore, S. D. Botts, Hezekiah Smith, and

Gillison Chloe (using methods described by Shapiro and Brannock, 1962), unless otherwise noted]

Sample No.

8-9..... .

8-13....... .............

GSC-4 ........ 8-2

GSC-L.. .

8-11........ ............

S-15.............. ......

SLB-596 » ...

LTS-4z .............

GSC-2-. ... ..... ....

S-12. .

8-10....................

GSC-3 .

Potassium Thorium Uranium 

(percent) (ppm) (ppm) '

1 O

1.9

2.2

1 Q

2.3

2.2

2.2

2.2

2.8

2.3

2.1

2.7

2.7 a2

as

8.7 ai

11.3 

7.1 

5.2 

8.5 

8.0 

9.1 

9.7 

5.8 

5.7 

7.5 

7.9 

6.9 

14.1

1.8 

1.5

as

1.4 

1.4 

2.2 

2.2 

1.4 

2.7 

1.4 

1.0 

1.6 

2.4 

1.8 

2.8

Ph/U -

48 

2.1 

3.4 

5.0 a? 

as 

ae

6.5

ae

41 

6.7 

47

as

as

6.0

Weight percent

SiO2

71.9 

72.7 

72.6 

72.5 

72.6 

73.3 

73.4 

748 

74.72 

75.3 

75.8 

75.4 

76.1 

76.9 

77.0

KiO

2.3 

2.3 

2.7 

2.3 

2.8 

2.7 

2.6 

2.7 

3.40 

2.79 

2.6

as 

as

3.9 

46

NasO

3.9

as

40 

3.9 

43 

40 

40 

3.9 

a 76 

412 

40

as a?

3.9 

3.5

CaO

CaO NasO+KaO

2.4 

2.4 

2.2 

2.5 

1.8 

1.6 

1.8 

1.5 

1.62 

1.9 

1.7 

1.3 

.95 

.44 

.54

0.39 

.39 

.33 

.40 

.25 

.24 

.27 

.23 

.23 

.27 

.26 

.18 

.14 

.06 

.11

Remarks

Foliated dark facies near border. 

Do. Contaminated {granodiorite. 

Typical central phase. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Leucocratic phase. 

Aplitedike.

Average 1 2.3 7.5 1.9 42 741 2.8 3.9 1.7 .26

1 Chemical data for sample SLB-596 from Larsen, Jr. (1948). 

1 Chemical data for sample LTS-4 provided by L. T. Silver. 

* Excluding aplite sample GSC-3.

U. S. GOVERNMENT PRINTING OFFICE : 1969 O - 339-847