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Data of Geochemistry

 *

Chapter D. Composition of the Earth's Crust

GEOLOGICAL SURVEY PROFESSIONAL PAPER 440-D

IPH
Data of Geochemistry

 

MICHAEL FLEISCHER, Technical Editor

Chapter D. Composition of the Earth's Crust

By RAYMOND L. PARKER

GEOLOGICAL SURVEY PROFESSIONAL PAPER 440-D

Discussion of methods of determining 

the crustal composition and a summary 

of abundance figures of the elements

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1967
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director

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

Washington, D.C. 20402 - Price 25 cents (paper cover)
DATA OF GEOCHEMISTRY, SIXTH EDITION

Michael Fleischer, Technical Editor

The first edition of the Data of Geochemistry, by F. W. Clarke, was published in 1908 as U.S. Geological 

Survey Bulletin 330. Later editions, also by Clarke, were published in 1911, 1916, 1920, and 1924 as Bulletins 

491, 616, 695, and 770. This, the sixth edition, has been written by several scientists in the Geological Survey 

and in other institutions in the United States and abroad, each preparing a chapter on his special field. The 

current edition is being published in individual chapters, titles of which are listed below. Chapters already 

published are indicated by boldface.

CHAPTEB A. The chemical elements

B. Cosmochemistry

C. Internal structure and composition of the earth

D. Composition of the earth's crust, by Raymond L. Parker

E. Chemistry of the atmosphere

F. Chemical composition of subsurface waters, by Donald E. White, John D. Hem, and G. A. 

Waring

G. Chemical composition of rivers and lakes, by Daniel A. Livingstone

H. Chemistry of the oceans

I. Geochemistry of the biosphere

J. Chemistry of rock-forming minerals

K. Volcanic emanations, by Donald E. White and G. A. Waring

L. Phase-equilibrium relations of the common rock-forming oxides except water, by George W. 

Morey

M. Phase-equilibrium relations of the common rock-forming oxides with water and (or) carbon 

dioxide

N. Chemistry of igneous rocks

O. Chemistry of rock weathering and soils

P. Chemistry of bauxites and laterites

Q. Chemistry of nickel silicate deposits

R. Chemistry of manganese oxides

S. Chemical composition of sandstones excluding carbonate and volcanic sands, by F. J. 

Petti John

T. Nondetrital siliceous sediments, by Earle R. Cressman

U. Chemical composition of shales and related rocks

V. Chemistry of carbonate rocks

W. Chemistry of iron-rich sedimentary rocks, by H. L. James

X. Chemistry of phosphorites

Y. Marine evaporites, by Frederick H. Stewart

Z. Continental evaporites 

AA. Chemistry of coal

BB. Chemistry of petroleum, natural gas, and miscellaneous carbonaceous substances 

CC. Chemistry of metamorphic rocks

DD. Abundance and distribution of the chemical elements and their isotopes 

EE. Geochemistry of ore deposits 

FF. Physical chemistry of sulfide systems 

GG. The natural radioactive elements 

HH. Geochronology

II. Temperatures of geologic processes

JJ. Composition of fluid inclusions

m
CONTENTS

Abstract_________________________________________

Introduction. ______________________________

Constitution of the earth.___________________________

Composition of the crust___________________________

General discussion ______________________________

Computations of crustal composition._____________

Major elements_______________________

Averages of available analyses.___________

Averages weighted in proportion to occurrence______________________________

Computations of an indirect nature. ______

Page 

Dl

1

1

2

2

3

3

3

4

6

Composition of the crust Continued

Computations of crustal composition Continued

Major elements Continued Page 

Abundance of elements based on crustal 

models. _____________________________ D8

Minor elements....-..----------..-------.-- 10

Problems in estimation of element abundance___ ___ 14 

Abundance in specific rocks____---_-_____----__-- 14

Abundance in the crust. ________________------_ 16

References..--.----___-___--------------.---------- 16

Index. _________________________________________ 19

ILLUSTRATIONS

FIGURES 1-3. Graph showing 

1. P and S velocity distributions in the earth's interior.________________________ Dl

2. Variation in density of the earth Model A____--_-_--__-_-------_-----_--__- 2

3. Crustal abundance of elements of atomic numbers 1-93______-_______--___-_ 12

TABLES

Page 

TABLE 1. Physical dimensions of earth shells, excluding biosphere.___________-____-__-_---_-- D2

2. Average composition of the lithosphere._____________________________ ____.___-. 3

3. Average composition of igneous rocks of the continents and oceanic islands and of the earth. 4

4. Areas of igneous rocks in the Pacific Cordillera and Appalachian regions.-..-.. __-.___ 5

5. Compositions of average igneous rock___.___________________..______-_------ - _ 5

6. Composition of the earth's crust in Finland and composition of the average igneous rock

for comparison.______________________________________________________________ 5

7. Distribution of plutonic rocks in Norway____-_______________-___-_--____---_--_-- 6

8. Average composition of the earth's crust and composition of the average igneous rock for

comparison..__--__-______-_--.--_-________-_-___-________________-___-_---_- 6

9. Average composition of Norwegian loams and other averages for comparison...__________ 6

10. Average igneous rock formed by combining granite and basalt in proportion 1:1 and other

averages for comparison_______________________________________________________ 7

11. Average igneous rock compositions computed by Mead and other averages for comparison. 7

12. Compositions of the average igneous rock________________________________________ 7

13. Rare-earth abundance patterns__________-______------_-_--_--_---_-_---_-_--------- 8

14. Average composition of all sediments___________---___---_--__---_------_---------- 9

15. Composition of the lithosphere________-_-_____________-___--____-_-----_-_--------- 10

16. Proportions of major crustal units_________________________--__-_-_-_--__-----_----- 11

17. Estimates of abundances of major oxides in continental crust_________._______----___ 11

18. Weight percentages of 25 of the most abundant elements in the earth's crust___-_--_---_- 13

19. Abundance of elements in certain types of rocks_____________________________________ 13

20. Abundance or elements in the earth's crust and in igneous rocks______________________ 15

21. Selected determinations of zirconium and strontium in granite G-l-__-_------_--------- 16

v
DATA OF GEOCHEMISTRY

COMPOSITION OF THE EARTH'S CRUST

By RAYMOND L. PARKER

ABSTRACT

The crust of the earth is composed principally of igneous (and 

metamorphic) rocks of granitic and basaltic composition. Since 

1890 many geologists have computed averages for the majorelement composition of the crust based on the following general 

approaches: (1) Averages of available analyses, (2) averages 

weighted in proportion to occurrence, (3) computations of an 

indirect nature based on the composition of sediments and 

various combinations of mafic and felsic rocks, and (4) abundances of elements based on crustal models. Most of these 

averages fall within a remarkably small range in composition. 

Less attention has been given by geologists to the computation of 

abundance of minor elements in the crust and in various types 

of rocks. The abundance of some minor elements still is poorly 

known, and the estimation of their abundance is hampered by 

lack of available analyses, inadequate sampling, inaccurate results of some analytical procedures, and imprecise methods of 

estimation.

Abundance figures for the chemical elements in the earth's 

crust and in the common rocks, as summarized from available 

literature, are presented.

INTRODUCTION

The crust of the earth is discussed in the following 

pages to serve as background for succeeding chapters of 

the "Data of Geochemistry." An attempt is made to 

present the data that relate to the composition of the 

lithic crust and to present the most recent tabulations 

of abundances of the elements in the crust and in certain 

general rock categories. A principal purpose of this 

chapter is to point out the problems involved in computing abundance figures and in determining accurately 

the composition of the crust. Our knowledge of crustal 

composition since about 1890 is presently through a 

summary of the most important works in this field.

The abundance data given in tables 19 and 20 will no 

doubt be subject to revision shortly after they are published because of the rapid accumulation of modern 

analytical data and the detailed compilation of data for 

each element now in progress. A final tabulation on 

completion of such compilation will be presented in 

chapter DD of the "Data of Geochemistry."

CONSTITUTION OF THE EARTH

The earth is considered to have a primary threefold 

division crust, mantle, and core. These divisions, 

which are concentric zones in depth, are established 

principally by their differing behavior with respect to 

the transmission of P (compressional) and 8 (shear) 

seismic waves and are separated from each other by distinct discontinuities in transmission velocity. The crust 

and the mantle are separated by the Mohorovicic discontinuity at an average depth below sea level ranging 

from 37 km under parts of the continents to about 11 km 

beneath the deep sea basins (Poldervaart, 1955); the 

mantle and core are separated by the Wiechert-Gutenberg discontinuity at a depth of approximately 2,900 

km. These discontinuities are clearly shown in figure 1, 

a plot of velocity of P and 8 waves versus depth in the 

earth. Inasmuch as the velocity of P and 8 waves varies with density and elasticity of the medium through 

which the waves pass, the curves indicate that the earth 

is heterogeneous in respect to these properties in zones

14

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3 5

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Wiechert-Gutenberg 

discontinuity

Core,

Crust

I 1 I

1000 2000 3000 4000 5000 

DEPTH. IN KILOMETERS

6000 7000

FIGURE 1. P and 8 velocity distributions In the earth's Interior. 

Modified from Bullen (1963, p. 223).

Dl
D2 DATA OF GEOCHEMISTRY

in depth separated by the above-mentioned discontinuities. That S waves have not been observed to pass 

through the central core suggests that part of the core 

is not rigid, as are other zones of the earth, and is probably in a fluid state. Keasons for believing that the 

inner part of the core is solid are discussed by Bullen 

(1963).

The average density of the earth was determined by 

Cavendish in 1799 to be about 5.5 g per cm3 (grams 

per cubic centimeter) ; a more precise recent estimate 

is 5.51T g per cm3 (Bullen, 1963, p. 226). Inasmuch 

as the surface rocks have a mean density of about 

2.8 g per cm3 , inner parts of the earth must consist of 

material with density greater than 5.5 to account for the 

density of the earth as a whole. A detailed mathematical treatment of the density variation in the earth is 

given by Bullen (1963, p. 229), showing the general 

increase in density to 11.9 g per cm3 for a depth within 

the core. (See figure 2.) Birch (1964) points out that 

densities proposed for the inner core by Bullen are excessive and are in conflict with modern shock-wave data. 

Inner-core densities of 12.86 and 13.26 g per cm3 for 

two earth models have been postulated by Clark and 

Eingwood (1964) and are considered plausible and consistent with those data.

The density distribution within the earth may be explained by a change in physical state of the material by 

contraction into smaller volume under great pressure 

or by a change in chemical composition involving 

heavier substances. Concepts currently favored by 

most physicists and geologists to explain the density 

variation with depth are based both on changes in physical state and chemical composition (Birch, 1964). The 

following constitution of the earth is consistent with

^ 5

Q 3

Core

Mantle

1000 2000 3000 4000 5000 

DEPTH, IN KILOMETERS

6000 7000

FIGURE 2. Variation in density of the earth Model A. Modified 

from Bullen (1963, p. 231).

known facts concerning its mass, moment of inertia, and 

seismic behavior.

Division Physical state Constituent material 

Crust____ Solid (with Heterogeneous, principally 

zones of fluid, normal silicate rocks but 

gas). including zones of water,

snow, and ice (hydrosphere) ; 

gas (atmosphere); and organic 

and skeletal matter 

(biosphere).

Mantle___ Solid__________ Iron-magnesium silicates, possibly dunitic or peridotitic 

material and iron sulfide(?).

Core_____ Partly fluid, Iron-nickel alloy, perhaps 

partly solid. containing silicon.

The physical dimensions of these divisions of the 

earth are summarized in table 1.

TABLE 1. Physical dimensions of earth shells, excluding biosphere 

[Data from Mason (1958, p. 41)]

Thickness (km)

3. 80 (mean)

2,883

3,471

6,371

Volume (X102? cm*1 )

0. 00137

.008

.899

.175

1.083

Mean 

density 

(gper 

cm3)

1.03

2.8

4.5

10.7

5.52

Mass 

(X10»g)

0. 000005

.00141

.024

4.075

1.876

5.976

Mass 

(percent)

0. 00009

.024

.4

68.1

31.5

100.0

COMPOSITION OF THE CRUST 

GENERAL DISCUSSION

The term "crust" stems from the early concept of a 

molten earth with a solidified outer crust. Our present 

concept of the earth's structure differs considerably, but 

the term has persisted and is now applied to the outer 

shell of the earth above the Mohorovicic discontinuity. 

Included in the crust are the geochemical spheres 

hydrosphere, atmosphere, and biosphere, which are 

subjects of detailed description in separate chapters of 

the "Data of Geochemistry." Only the lithic crust 

above the Mohorovicic discontinuity will be described 

here.

The term "lithosphere" has been applied to the lithic 

crust of the earth by other writers (Clarke and Washington, 1924; Poldervaart, 1955) and is used interchangeably with lithic crust in this report. As pointed 

out by Eankama and Sahama (1950, p. 82), lithosphere, 

as contrasted to asthenosphere, should refer to strength 

or state of the constituting material and, as originally 

defined, should not connote chemical composition. Subsequently, the term "steriosphere" was proposed by 

Bucher (1955, p. 344) for this relatively strong outermost shell of the earth above the asthenosphere, but the 

term has been little used. It seems pointless to attempt 

to refine lithosphere from what it has come to mean 

through usage.
COMPOSITION OF THE EARTH'S CRUST D3

The lithic crust is frequently and simply referred to 

as consisting of two layers sial and sima. In this 

designation, the sial represents the upper part of the 

crust of silicic composition and derives its name from 

silicon and aluminum, which together with oxygen, are 

the most abundant elements in the material of this 

region. The sima refers to the underlying, more mafic 

part, of the crust and derives its name from siliconmagnesium. A less commonly used term "sialma" refers to an intermediate position between the sial and 

sima (Rankama and Sahama, 1950, p. 81). These terms, 

though imprecise, have convenient application in some 

structural and petrologic studies.

The crust of the earth is composed principally of 

igneous rocks and contains only a minor amount of 

sedimentary and metamorphic rocks, if the crust is considered as a whole. The proportions of different classes 

of rocks in the crust have been cited by Clarke and 

Washington (1924, p. 32) as consisting of 95 percent 

igneous rocks (including metamorphic rocks) and 5 

percent sedimentary rocks (consisting of 4 percent 

shale, 0.75 percent sandstone, and 0.25 percent limestone). Succeeding workers have not greatly revised 

these early estimates. Poldervaart (1955) calculated 

that the crust, including areas beneath the oceanic 

basins, contains 6 percent sedimentary rocks. Obviously the composition of the crust is close to the composition of igneous rocks.

COMPUTATIONS OF CRUSTAL COMPOSITION 

MAJOR EI^EMENTS

Studies aimed at determining the composition of the 

earth's crust have been made over a period of more than 

75 years, and considerable controversy has arisen over 

the approaches to the problem as well as to the values 

proposed. Four general approaches in determining 

crustal composition that have evolved during this period are (1) averages of available analyses, (2) averages weighted in proportion to occurrence, (3) computations of an indirect nature based on the composition 

of sediments and various combinations of mafic and 

felsic rocks, and (4) abundance of elements based on 

crustal models. All approaches except the last are concerned chiefly with the continental crust or parts of the 

crust and do not take into consideration the more than 

half of the earth's crust covered by the oceans.

AVEKAGES OF AVAILABLE ANALYSES

Early studies by Clarke (1889, 1908), Washington 

(1903), and Harker (1904) derived figures for the composition of the average igneous rock based on the arithmetic mean of a large number of chemical analyses. A

final paper by Clarke and Washington (1924) on the 

composition of the earth's crust was based on computations from 5,159 superior analyses compiled by Washington (1917). The work included averages grouped by 

geographical areas as well as figures for the crust of the 

earth as a whole. Averages of analyses grouped on a 

geographical basis were found to agree fairly well from 

one area to another, provided the areas chosen were 

large enough to eliminate local variations. Grout 

(1938) revised the average for the Canadian Shield 

area by using more recent analyses not available to 

Clarke and Washington.

On the basis of 95 percent igneous rocks, 4 percent 

shale, 0.75 percent sandstone, and 0.25 percent limestone, Clarke and Washington (1924) computed the 

average composition of the lithosphere to a 10-mile 

depth. Their averages for igneous rocks, shale, sandstone, and limestone, and the weighted average for the 

lithosphere are given in table 2. The average for the 

lithosphere differs little from the average given for 

igneous rocks.

TABLE 2. Average composition of the lithosphere according to

Clarke and Washington (1924, p. 82}

[Tr, trace]

SiO.~_ _ 

Ti02 ____------

A1203 _ _______

Fe203 ---------

FeO~-_ _

MgO_____---_-

CaO _

~Na_0--_ 

K2O_______---

H2 0--_ 

CO2 ------- 

ZrO2 _ _- - _

P_06 _ 

Cl______ ____

F_. ___________

SO3 ---------_-

S __ _ __

(Ce, Y) 2 03 _____

CraOs-- -

V_08 _ -----

MnO_______--_

NiO __ _______

BaO.__ 

SrO ________

Li2O_ _ ___

Cu____________

C._ -----

Total __ __

l

59.12

1.05

15.34

3.08

3.80

3.49

5.08

3.84

3. 13

1. 15

. 10

. 04

. 30

.05

.03

.05

. 02

.06

.03

. 12

.03

.05

.02

.01

.01

.00

100. 00

2

58.11

.65

15.40

4.02

2.45

2. 44

3. 10

1.30

3.24

4.99

2.63

.17

.65

Tr

.05

.00

Tr

.80

100. 00

3

78.31

.25

476

1.08

.30

1. 16

5.50

.45

1.32

1.63

5. 04

.08

Tr

.07

Tr

. 05

.00

Tr

100. 00

4

5.19

.06

.81

} .54

7.89

42. 57

. 05

.33

.77

41. 54

.04

.02

.05

.09

.05

.00

.00

Tr

100. 00

5

59.07

1.03

15.22

f 3.10

X 3.71

3.45

5. 10

3.71

3. 11

1.30

.35

.04

.30

.05

.03

.06

.02

. 05

.03

. 11

.03

.05

.02

.01

. 01

.04

100. 00

1. Average Igneous rock.

2. Average shale.

3. Average sandstone.

4. Average limestone.

5. Weighted average lithosphere: 

Igneous rock, 95 percent 

Shale, 4 percent 

Sandstone, 0.75 percent 

Limestone, 0.26 percent

Many objections to the validity of the averaging 

method of Clarke and Washington for determining the 

average composition of igneous rocks of the crust have
D4 DATA OF GEOCHEMISTRY

been raised, but the Clarke and Washington figures are 

close to those derived by more recent and sophisticated 

methods. Principal objectors were Daly (1914), Sederholm (1925), and Vogt (1931), and the principal objections were that the averaging method did not take into 

account the irregular geographic distribution of the 

analyses, that the analyses used in calculations were not 

proportional to the mass of rocks they represented, and 

that rare and unusual rocks were given undue weight 

in the calculations because of the abundance of analyses 

of these types of rocks in the literature. The objections 

were countered by Clarke and Washington (1924, p. 7)

who pointed out that, even though the analyses were not 

truly representative in terms of the abundance of rocks 

as they occur in the earth, they showed that the rocks 

varied from persilicic to subsilicic, and in the average 

these variations tended to offset each other and approximate the true mean. Such compensation, because of the 

wide ranges in composition of the unusual rocks, also 

tended to produce an average near the true mean. 

Inasmuch as the averages for individual continents were 

in fair agreement, unequal analytical coverage of areas 

was considered not to invalidate the overall average. 

(See table 3.)

TABLE 3. Average composition of igneous rocks of the continents and oceanic islands and of the earth

[Clarke and Washington (1924 p. 15)]

Si02 . __________________________

TiO___ -_ _ .._...___._....

A12 03 -- _ - ___ __.- _ _ _____

Fe2 03 - _____________________

FeO__.__._____________________

MgO._ ..---_... ..____. _______

CaO--. _____ _ _ __ _ ___ __

Na2 0-_-_..________. ._____.__._

K2 0__.____.________. ._______._

H2 0+_____._._______. ..___._..

P2 05 --_-_____ __________________

MnO._ _____ _____

Others________ ___ _____ _ _ __

Total. __________________

i

60. 19

1.01

15.76

2. 87

3. 67

3. 16

4.80

3.90

3.07

1. 01

. 26

. 10

. 20

100. 00

2

61. 34

.56

15. 20

3.03

3. 30

3. 47

4 88

4. 09

2. 69

1. 05

. 11

. 12

. 16

100. 00

3

59.84

.83

15. 12

3. 17

3. 67

3.61

4. 97

3. 73

3. 40

1. 24

. 23

08

. 11

100. 00

4

58. 21

.84

15.28

3.52

3. 73

3. 51

5. 09

4.83

3.28

1. 26

.20

. 07

. 18

100. 00

5

50. 59

1. 63

15.81

4. 44

5. 79

5. 79

7. 36

4 27

2. 31

1.47

. 43

.04

.07

100. 00

6

61.92

.68

15. 49

3. 17

2.75

2.63

450

4 10

3. 23

1. 23

. 12

. 10

.08

100. 00

7

60. 16

1.01

1474

2. 60

4. 41

3. 76

5. 03

3. 50

3. 03

1. 19

. 26

. 15

. 16

100. 00

8

50. 03

1. 96

15. 51

3.88

6. 23

6. 62

7.99

4. 00

2. 10

1. 16

. 25

. 15

. 12

100. 00

9

53. 66

.87

16. 82

4. 01

5. 34

467

7. 59

3. 58

2. 32

.93

. 17

. 03

.01

100. 00

10

59. 12

1.05

15.34

3. 08

3. 80

3. 49

5.08

3. 84

3. 13

1. 15

. 30

. 12

.50

100. 00

1. North America including Greenland, Mexico, Central America, and West 

Indies: 1,709 analyses.

2. South America: 138 analyses.

3. Europe: 1,985 analyses.

4. Africa continental: 223 analyses.

5. South Atlantic Islands: 56 analyses.

AVERAGES WEIGHTED IN PROPORTION TO OCCURRENCE

A more quantitative approach to the determination 

of the composition of segments of the earth's crust was 

conceived by Daly (1914), coincident with his objections to the methods of Clarke and Washington. His 

approach was based on the use of geologic maps in estimating the relative abundance of rock types. Using 75 

U.S. Geological Survey folios covering parts of the 

Appalachian and Cordillera regions of the United 

States, Daly measured the areal extent of the principal 

classes of plutonic, hypabassal, and extrusive rocks 

(table 4). He also compiled the average compositions 

of many types of igneous rocks. Knopf (1916), however, first used these data to compute a composition for 

the average igneous rock (table 5), which is very similar 

to the composition computed by Clarke and Washington 

(1924) by their method of averaging available analyses.

Sederholm (1925) computed an average composition 

of the earth's crust within the borders of Finland by 

using the areal distribution of various types of rocks 

and their chemical compositions in a manner similar to 

Knopf's as the basis for his computations. From geo6. Asia continental: 114 analyses.

7. Australia including Tasmania: 287 analyses.

8. Polynesia: 72 analyses.

9. Antarctic continent: 103 analyses.

10. The earth: 5,159 analyses.

logic maps he deduced the following percentages of 

rocks as the principal groups that constitute the Finnish 

crust:

Granitic rocks 52.5

Migmatites _ 21.8

Granulites (leptynites) 4.0

Schists ___________-_____ 9.1

Quartzites and sandstones 4.3

Limestones and dolomites .1

Mafic rocks________ 8.2

Total _______ 100.0

His average composition for the crust is considerably 

more silicic than averages for other regions and is shown 

in table 6, along with other averages for comparison. 

Column 2, table 6, is the average igneous rock computed 

by Clarke and Washington (1924) for Finland including the Kola Peninsula. The inclusion of some 

unusual (alkalic) Kola rocks in the average probably 

lowered the silica content, modified other oxide percentages, and thus accounted at least in part for the 

differences between the Sederholm and Clarke and 

Washington averages.
COMPOSITION OF THE EARTH'S CRUST D5

TABLE 4. Areas of igneous rocks in the Pacific Cordillera and 

Appalachian regions

[Compiled by Daly (1914, p. 44)]

Pacific 

Cordillera 

region (sq mi)

Appalachian 

region (sq mi) Total (sq mi)

Platonic rocks

Paleozoic and later granite__

Quartz monzonite_____ _ _

Quartz diorite. ___________

Gabbro____ _____ _ _

Anorthosite _ _ _ _____ _

Fergusite. __ _______

Theralite _ __ _____ _

Peridotite___ ______ _____

Pyroxenite _________

Total- _ _ .....

2, 089. 0 

402. 0 

(2, 491. 0) 

2, 040. 0

11. 0 

45.3 

103.5 

98. 5 

226.4 

52. 0 

24.4 

17.5 

3.5 

8.7 

<1. 0

a 3

73.3 

2.2

5, 240. 7

1, 151. 0 

194. 0 

(1,345.0)

10.6

47.5

.3

1, 402. 8

3, 240. 0 

596. 0 

(3,836.0) 

2, 040. 0 

11. 0 

45.3 

113. 5 

98.5 

273.9 

52.0 

24. 4 

17. 5 

3.8 

8.7 

<1.0 

. 1 

6.3 

73.3 

2.2

6, 607. 5

Hypabyssal rocks

Quartz porphyry and 

rhyolite__ __ ________

Dacite porphyrite. ________

Quartz-hornblende

Quartz monzonite porphyry.

Monzonite porphyry. __

Nepheline syenite porphyry.

Pseudo-leucite porphyry___ 

Total

17.9

26.5

7.8

2. 0 

46 

20. 1 

1.0 

3.0 

150. 0 

38.4 

9.4 

< 1 

2.7 

.5

284.0

2.0 

1.0

1.6

118.0 

2.5

125. 1

19.9

27.5

7.8

2. 0 

46 

21.7 

1. 0 

3. 0 

268.0 

40.9 

9.4

<. 1

2. 7 

. 5

409. 1

Extrusive rocks

Rhyolite__ ______________

H ornblende andesite. ______

Pyroxene andesite (chiefly).

Basalt-.- ________ ...

Trachyte.- ______________

Phonolite __ ______ ______

Teschenite ___ ______ _ __

Nepheline basalt (Texas) ___ 

Nepheline-melilite basalt- __ 

Limburgite. ___________ _

Quartz basalt_____________

Total___________.__

Total igneous rock 

area mapped _

2, 145. 7 

82. 1 

3. 0 

21.6 

3, 966. 0 

255. 0 

3, 079. 0 

6. 5 

4.6 

5. 5 

.3 

.2 

1.2 

2.8 

2.5 

8. 0

9, 584. 0

15, 072. 7

1.0

130.0

131.0

1, 658. 9

2, 146. 7 

82. 1 

3. 0 

21.6 

3, 966. 0 

255. 0 

3, 209. 0 

6.5 

46 

5.5 

.3 

.2 

1.2 

2.8 

2.5 

8.0

9, 715. 0

16, 731. 6

TABLE 5 Compositions of average igneous rock

SiO2 _________ ____

TiO2 ___. _________________

A12O3 _ __ __ ___ ...

Fe2O3 _____ _ ________

FeO __ -__ _________

MnO __ .... _______ _ MgO _ __________________

CaO ___ _ _____________

Na2O __ ___--_-____-_____

K2 0 ____ _ _____ __ _ _

H2O-__. __--________-__.

H20+___ ____________

P.OB 

Others. ____ _ _____ ___

Total _ ___ ______

tion of the average i

Si02 _ ___ _ ...........

TiO2 ____ .__ __ _ ......

Al2O3 -------_ ------

Fe2O3 -- _ ____ ......

FeO_- ______ _______

MnO __ ___- . _

MgO _ ____ ___ __ _ ___

CaO

NasO... ................ .

K2 0 __ __________________

H,0_. ...................

P.05 ...... ......

Others ___________

Total ___________

compositions computed by 

Knopf from 

Daly's data 

(1916)

61.64 

.73 

15.71 

2.91 

3.25 

.16 

2.97 

5.06 

3.40 

2.65

} 1.26 

.26

100. 00

Clarke 

(1915)

60.47 

.80 

15.07 

2.68 

3. 50 

. 10 

3.85 

488 

3.41 

3.03

r .48

\ 1.44 

.29

100. 00

Clarke and 

Washington 

(1924)

59.12 

1.05 

15.34 

3.08 

3.80 

. 12 

3.49 

5.08 

3.84 

3. 13

} 1.15

.30 

.50

100. 00

earth's crust in Finland and compost 

ffneous rock for comparison

1

67.70 

.41 

14.69 

1.27 

3. 14 

. 04 

1.69 

3.40 

3.07 

3.56 

.79 

. 11 

. 13

100. 00

2

60. 58 

. 56 

16.43 

2. 75 

2.88 

.19 

2. 16 

3.35 

6. 11 

3.96 

.71 

.27 

.05

100. 00

3

59. 12 

1.05 

15.34 

3.08 

3.80 

.12 

3.49 

5.08 

3.84 

3.13 

1.15 

.30 

.50

100. 00

1. Sederholm (1925), average Finnish rocks. 

2. Clarke and Washington (1924), average igneous rock, Finland including Kola, 

59 analyses. 

3. Clarke and Washington (1924), average igneous rock, earth.

Vogt (1931) calculated the average composition of 

the earth's crust after extensive field work in Norway. 

His calculations were based on averages of plutonic rock 

types computed by Daly or by himself and on his experience as a mapping geologist in estimating the relative 

distribution of the plutonic rocks. Only plutonic rocks 

were considered; hypabyssal, extrusive, and sedimentary rocks were excluded from consideration. The distribution of igneous rock types, as conceived by Vogt, is 

given in table 7, 'and his crustal averages are given in 

table 8. Both tables present two sets of values based 

on suppositions that the relative abundance of granite 

is either 50 or 60 percent. 

Vogt's averages are somewhat more rich in silica, but 

less rich in ferrous and ferric oxides, magnesia, and lime, 

than the Clarke and Washington average. Vogt's figures for titania and phosphorus pentoxHe a.:6 also con-
D6 DATA OF GEOCHEMISTRY

siderably lower, facts which are 'strongly emphasized in 

his objections to the Clarke and Washington average.

TABLE 7. Distribution of plvtonic rocks in Norway 

[Compiled by Vogt (1931)]

Granite __ ____ _______

Quartz-monzonite and granodiorite__-_ 

Quartz-diorite and diorite_____ _

Pyroxenite and peridotite.

Nordmarkite and pulaskite _

Essexite and others ____ ___

Total _ ______ _.__ _____ __ __

Relative abundance of granite 

assumed to be 

50 percent

50 

10 

8 

18 

4 

.50 

1 

3 

4 

1 

.50

100

60 percent

60 

9 

6 

15 

3 

.25 

1 

2 

3 

.50 

.25

100

TABLE 8. Average composition o/ the earth's crust (Vogt, 1931) 

and composition of the average igneous rock for comparison

Si02 

Ti02 ----------------

Al_08 ~~ - -------

Fe_08 

FeO_--___ _--__

MgO --- 

CaO _ _ _ _ __ __ _

Na_0~ ----------------

K2 0_ __- 

H.O+ _ 

C0__ 

P2 0,____ ___. _ _

Other_____-____--______

Total _ ___ _____

i

64.03

.60

15.71

2.20

2. 66

2.67

4.62

3.51

3. 52

. 18

.30

100. 00

2

65.73

. 55

15.41

2. 10

2.30

2.23

4. 01

3. 43

3.79

. 17

.28

100. 00

3

59. 12

1.05

15.34

3. 08

3.80

3.49

5.08

3.84

3. 13

1. 15

. 10

.30

.52

100. 00

4

59.87

1.06

15.54

3. 12

3.85

3.53

5. 14

3.89

3.17

.30

CQ

100. 00

1. Vogt's crustal average with granite assumed to be 50 percent of plutonic rocks, 

water free.

2. Vogt's crustal average with granite assumed to be 60 percent of plutonic rocks, 

water free.

3. Igneous rocks, Clarke and Washington (1924).

4. Igneous rocks, Clarke and Washington (1924), water and carbon dioxide free.

COMPUTATIONS OF AN INDIRECT NATURE

Indirect approximations of the composition of the 

earth's crust have been made by determining the composition of the products of crustal weathering and erosion and by combining the analyses of mafic and f elsic 

rocks in various proportions. Some computations involve equating the erosion products with combined mafic 

and felsic rocks. Supporters justify these approaches 

on the basis that the products of decomposition of the 

crust should reflect the original crustal composition and 

that the crust can well be represented by mafic and felsic 

rocks inasmuch as they are the principal types exposed. 

(See table 4.)

Goldschmidt (1933,1954) conceived the idea that the

glacial clays in southern Norway represent a natural 

sampling of the continent as a result of glacial erosion 

by the Fennoscandian ice sheet. The glacial erosion 

was largely mechanical with a minimum of chemical 

weathering, so that the composition of the resulting 

glacial clays should be close to that of the original rock 

flour. Furthermore, the rock flour should have been 

well mixed during transportation in the ice and in the 

melt water before deposition. An average of 77 analyses of the glacial clays (table 9) is in remarkable agreement with the average igneous rock of Clarke and Washington (1924), except for sodium and calcium which are 

considered to have been leached to some degree in the 

aqueous environment of transportation and deposition. 

Instead of calculating the crustal composition, a number of geologists have combined the analyses of granite 

(felsic rocks) and basalt (mafic rocks) in various proportions to approximate the average for the crust. 

Daly (1910, p. 238) was one of the first to point out 

that the mean of his average granite and average basalt 

approximated his average diorite and andesite. This 

average is remarkably close to the average igneous rock 

of Clarke and Washington (1924) (table 10). Daly's 

observations were in accord with the views of Loewinson-Lessing (1911), who regarded the crust as derived 

from two fundamental magmas granitic and basaltic. 

He erred, however, in suggesting that the average 

should be syenite instead of a rock of more intermediate 

composition (Daly, 1914, p. 169).

TABLE 9. Average composition of Norwegian loams (clays') and 

other averages for comparison

SiOs 

TiOa-- 

AlsOs------

FeaOa--- -

FeO 

MnO-- 

MgO 

CaONa_O._ KjO - -

HjO .

P_0_-_ .

SOs-- -

S ~ 

fCta

Total. -.

Goldschmidt (1954)

Norwegian loams

Primary 

zone

58.94 

.79 

15.87 

3.28 

3.69 

.10 

3.33 

3.19 

2.05 

3.95 

3.01 

.21 

.09 

.08 

.60

99.18

Secondary 

zone

60.82 

.78 

15.48 

4.35 

2.82 

.12 

3.02 

2.25 

2.00 

3.83 

3.10 

.23 

.05 

.03 

.18

99.06

Mean

59.19 

.79 

15.82 

3.41 

3.58 

.11 

3.30 

3.07 

2.05 

3.93 

3.02 

.22 

.08 

.07 

.54

99.18

Clarke and Washington 

(1924)

Average igneous rock

Earth

59.12 

1.05 

15.34 

3.08 

3.80 

.12 

3.49 

5.08 

3.84 

3.13 

1.15 

.30

.05 

.10 

.35

100.00

Norway 

and 

Iceland

59.83 

1.64 

16.08 

3.65 

3.21 

.10 

2.26 

3.64 

5.10 

3.52 

.75 

.12

.10

100.00

Average 

composition lithesphere

59.07 

1.03 

15.22 

3.10 

3.71 

.11 

3.45 

5.10 

3.71 

3.11 

1.30 

.30

.06

.35

.38

100.00

Vogt (1931)

Average composition earth's 

crust; granite 

in plutonic 

rocks assumed 

to be 

50 percent i

64.03 

.60 

15.71 

2.20 

2.66

2.67 

4.62 

3.51 

3.52

.18

.30

100. 00

60 percent i

65.73 

.55 

15.41 

2.10 

2.30

2.23 

4.01 

3.43 

3.79

.17

.28

100.00

i See tables 7 and 8. Vogt's averages are computed on a water-free basis; hence 

allowance must be made in comparison with other averages in this table.
COMPOSITION OF THE EARTH'S CRUST D7

TABLE 10. Average igneous rock formed by combining granite and 

basalt in proportion 1:1 and other averages for comparison

Si02 ________

TiO__- ______

A1203- __ 

FejsOs ______

FeO __ ____

MnO ________

MgO- _ ___

CaO---__ 

NaaO __ ___

K20_ __ _ _

P208 -______

Others ______

Total _

Daly (1914, p. 169)

Average 

granite

70.47 

.39 

14.90 

1.63 

1.68 

.13 

.98 

1 2. 17 

3.31 

4. 10 

.24

100. 00

Average 

basalt

49.65 

1.41 

16. 13 

5.47 

6.45 

.30 

6. 14 

9.07 

3.24 

1.66 

.48

100. 00

Mean

60.06 

.90 

15.52 

3.55 

4.06 

.21 

3.56 

5.62 

3.28 

2.88 

.36

100. 00

Clarke and Washington 

(1924)

Average igneous rock

Earth

59. 12 

1.05 

15.34 

3.08 

3.80 

. 12 

3.49 

5.08 

3.84 

3. 13 

.30 

1.65

100. 00

Earth 

(water and 

carbon 

dioxide 

free)

59.87 

1.06 

15.54 

3. 12 

3.85 

. 12 

3.53 

5. 14 

3.89 

3. 17 

.30 

.41

100. 00

i Includes 0.06 percent BaO and 0.02 percent SrO

Mead (1914), assuming that the average igneous rock 

could be approximated in composition by some combination of average granite and average basalt, calculated a 

65:35 ratio of granite to basalt to best explain the composition of sediments as expressed by average analyses of 

shales, sandstones, and limestones. Simultaneously, 

with the solution of the granite: basalt ratio, a ratio of 

87:8: 5 was calculated for shale, sandstone, and limestone, respectively. Mead's equation for the calculation, which he solved by graphical means, is as follows: 

x granite+y basalt=a shale+<b sandstone+c limestone 

where average analyses of granite, basalt, shale, sandstone, and limestone are given. Solve for a?, y, a, 5, 

and c.

Average granite and basalt analyses (Daly, 1910) 

combined in proportions of 63:35 give a composition 

which is slightly more silicic than that of Clarke and 

Washington (1924) and the more modern averages of 

Poldervaart (1955) and Taylor (1964). It is indeed 

close to the crustal averages computed by Vinogradov 

(1962) using a 2:1 granite:basalt ratio (see table 11).

In a modern version of Mead's method, Wickman 

(1954) derived a ratio in which granite : basalt=2.13dr 

0.70, and from this he determined the average igneous 

rock to be almost identical in composition with that 

derived by Knopf (1916). Averages of several authors 

and computations of igneous rock compositions by Wickman can be compared in tables 11 and 12. His computation of the proportions of the sediments formed by 

complete weathering of the continents is, in percent, as 

follows: shale, 82.3; sandstone, 8.3; limestone, 6.1; and 

dolomite, 3.3.

243-569 67 2

TABLE 11. Average igneous rock compositions computed by Mead 

(1914) and other averages for comparison

Si02 __ ___

Ti02 -~- - _ --

A1203 ______

Fe203 -_ ....

FeO __ ._..-_

MgO _______

CaO ______._..

NaaO ___ __._

K20_. ________

Others- _______

Total _____

i

63. 19

.74

15.34

2.96

3.35

2.79

4.59

3.28

3.24

.52

100.00

2

60.3

1.0

15.6

7.2

3.9

5.8

3.2

2.5

.5

100.0

3

63.1

.8

15.2

6.0

3.1

4. 1

3.4

3.0

1.3

100.0

4

59.4

1.2

15.6

2.3

5.0

4.2

6.6

3. 1

2.3

.3

100.0

5

59.87

1.06

15.54

3. 12

3.85

3.53

5.14

3.89

3.17

.83

100. 00

1. Average granite and average basalt of Daly (1910) combined in ratio of 65:35 (Mead, 

1914). water free (computation corrected by Parker).

2. Taylors felsic and mane rock combined in ratio of 1:1 (Taylor, 1964); total Fe 

expressed as FeO; water free.

3. Vinogradov's granite and basalt combined in ratio of 2:1 (Taylor, 1964); total Fe 

expressed as FeO; water free.

4. Poldervaart's (1955) average continental shield and folded belts regions; water free.

5. Average igneous rock, Clarke and Washington (1924); water and carbon dioxide 

free.

TABLE 12. Compositions of the average igneous rock (Wickman, 

1954) and other averages for comparison

Si02 _ _ ______

Ti02 _________-

A12 03 __________

FeaOj, __ . _ .

FeO

Fe (total) 1 __ .

MnO ____--

MgO. __ _____

CaO---_--_-_-

Na20_ ________

K2 0____ __.

P205 _ ______

Others ________

Total.. _

i

61.45

.89

15. 19

2.02

5. 05

(5. 34)

. 14

3.55

6.01

3. 10

2.42

.24

100.06

2

62.90

.80

15.22

1.96

4.43

(4.81)

.13

3.08

5.40

3.22

2.65

.23

100. 02

3

63.90

.74

15.24

1.90

4.02

(4.45)

.13

2.76

5.00

3.30

2.80

.23

100. 02

4

59.87

1.06

15.54

3.12

3.85

(5. 17)

. 12

3.53

5.14

3.89

3. 17

.30

.41

100. 00

5

62.44

0.74

15.91

2.95

3.29

(4.62)

0.16

3. 01

5. 12

3.44

2.68

.26

100. 00

i Not included in analysis total.

1. Igneous rocks, Wickman (1954), with granite:basalt=1.43.

2. Igneous rocks, Wickman (1954), with granite: basalt =2.13.

3. Igneous rocks, Wickman (1954), with granite: basalt =2.83.

4. Igneous rocks, Clarke and Washington (1924), water and carbon dioxide free.

5. Average of Cordillera and Appalachian rocks, Knopf (1916), water free.

Taylor (1964) concluded from a study of the relative 

abundances of rare-earth elements in sedimentary and 

igneous rocks that both the major and minor element 

compositions of the continental crust can be represented by a 1:1 mixture of mafic and felsic rocks. He 

found that such a mixture of specially selected mafic 

and felsic rocks contained approximately the same 

rare-earth abundance pattern as sedimentary rocks, as 

well as nearly the same composition, in terms of major 

oxides, as the continental rocks computed by Poldervaart (1955) and the lithosphore by Clarke and Washington (1924). (See table 11.)

Taylor pointed out that because sedimentary rocks 

of diverse origin and differing ages have similar rareearth abundance patterns, no significant fractionation 

of rare-earth elements occurred during the course of
D8 DATA OF GEOCHEMISTRY

sedimentation, and a thorough mixing of distinctly 

different rare-earth igneous patterns was accomplished. 

The sedimentary rare-earth abundance pattern should 

represent both a large scale sampling and an average 

pattern of the continental rocks exposed to weathering. 

Inasmuch as the chief types of crustal rocks are mafic 

and felsic, duplication of the sedimentary rare-earth 

abundance pattern by combining these types should, in 

principle, give their proportion in the continental 

crust.

Mafic and felsic rock analyses selected to represent 

the crustal rocks have been averaged from several available standard rocks. The mafic rocks are a composite 

of the Atlantic Ridge, Experimental Mohole, Columbia River, and Kilauea Iki basalts and diabase W-l 

from Centerville, Va. The felsic rocks are represented 

by an average of the Kirovograd granite and the granite 

G-l from Westerly, R.I. Rare-earth values are normalized on the basis of lanthanum equals 1.00 and are 

shown in table 13. The table shows also that the average sedimentary pattern is very similar to the 1:1, 

mafic: felsic composite pattern which is a weighted 

average computed on the basis of the average abundance of lanthanum of 50 ppm (parts per million) and 

10 ppm in granite and basalt, respectively (Taylor, 

1965).

TABLE 13. Rare-earth abundance patterns (weight ratio) normalized^to lanthanum= 1.00

[Data from Taylor (1964,1965)]

Atomic 

No.

57

58

5Q

60

61

62

63

64

65

66

67

68

69

70

71

Element

Cerium__ __ ____

Neody mium_ _____

Pr omethium _ _

Samarium. _ _ _ _

Dysprosium ____

Holmium_ __

Erbium. _ _ _ _

Thulium

Lutetiumu _

1

1 00

2 0

27

90

20

040

18

030

12

040

09

016

10

017

2

1.00

4.25

53

2 60

80

32

1 21

21

28

88

12

63

14

3

1 00

1 58

20

62

10

0094

057

0030

018

0034

0090

0016

0035

0008

4

1 00

2 02

26

95

22

062

25

038

050

16

022

11

023

1. Average rare-earth sedimentary rock pattern (Haskin and Qehl, 1962).

2. Average mafic rock pattern. Average of Atlantic Ridge and Experimental 

Mohole basalts (Frey and Haskin, 1964), Columbia River and Kilauea Iki 

basalts (Schmitt and others, 1963), and diabase W-l (Haskin and Qehl, 1963).

3. Average felsic rock pattern. Average of granite G-l (Haskin and Qehl, 1963) 

and Kirovograd granite (Gavrilova and Turanskaya, 1958).

4. Rare-earth pattern resulting from averaging mafic pattern (col. 2) and felsic pattern 

(col. 3) weighted In the ratio of 1:5, mafic:felsic patterns, respectively.

ABUNDANCE OF ELEMENTS BASED ON CRUSTAL MODELS

The most realistic estimates of the composition of the 

earth's crust were made by Poldervaart (1955) and 

Pakiser and Robinson (1967). In reviewing chemical 

and geological data pertaining to the crust, Poldervaart

calculated the masses of the major rock-forming elements in terms of their oxides and computed the average 

composition of the lithosphere down to the Mohorovicic 

discontinuity. Pakiser and Robinson computed the 

composition of the crust underlying the conterminous 

United States by using seismic data to determine the 

distribution and proportion of mafic and silicic rocks 

and by using average compositions of mafic and silicic 

rocks to deduce abundance of the major oxides.

For convenience Poldervaart divided the lithosphere 

into four structural divisions: the deep oceanic region, 

the suboceanic region, the continental shield region, and 

the region of young folded belts. The deep oceanic 

and suboceanic regions embrace the pelagic, hemipelagic, and continental shelf areas, and the continental 

shield and young folded-belts regions (including volcanic islands) essentially compose the continental 

masses. The following discussion is condensed from 

Poldervaart's paper.

Pelagic, hemipelagic, and shelf sediments cover an 

area of about 361X106 km2 (square kilometers) in the 

oceanic regions. Pelagic sediments consisting of calcareous sands and oozes, red clay, and siliceous oozes 

in a volume ratio of 72:19:9, respectively, cover an area 

of 268 X106 km2 and have an average thickness of 0.3 

km. Hemipelagic sediments underlie an area of about 

63 X106 km2 and consist of terrigenous mud, coral mud, 

and volcanic mud in a volume ratio of about 74:22:4, 

respectively. Shelf sediments cover about 30 X106 km2 

and have an average thickness of 4 km. Their composition is considered to be similar to the sediments in 

the young folded-belts region, which is made up of the 

following constituents, in percent: Shale, 52; sandstone, 

13; limestone, 22; graywacke, 5; andesite, 6; and rhyolite, 2. The composition and masses of oxides of the 

oceanic sediments and the average composition and total 

masses of the sediments for this part of the crust are 

listed in table 14.

Igneous rocks lying beneath the oceanic sediments and 

above the Mohorovicic discontinuity are poorly known 

and, thus, somewhat arbitrarily assigned. In the deep 

oceanic region, underlying material is considered to be 

olivine basalt about 5% km thick. In the suboceanic 

region, including the shelf area, 4 km of rocks of dioritic 

composition grading downward into 2 km of tholeiite 

followed by 5 km of olivine basalt are taken to represent the underlying material.

The continental masses contain a solid sedimentary 

rock cover averaging about half a kilometer in thickness 

for the continental shield region and about 5 km in 

thickness for the young folded-belts region. The area! 

extent of the continental shields is about 105 X106 km2 

and that of the young folded belts is 42 X106 km2. The
COMPOSITION OF THE EARTH'S CRUST D9

TABLE 14. Average composition of all sediments 

[Calculated by Poldervaart (1955)]

Region SiOj TiOj A12 03 FesOa FeO MnO MgO CaO Na2 0 K2 0 P2 06 COa Total

Mass (X10« tons)

Young folded belts- _ _ _ _

All sediments __.-__

61. 8

84. 8

176. 5

434. 2

757.3

0.9

.6

1.7

7.0

10. 2

17. 6

12.4

38.8

116. 6

185. 4

10. 9

3.4

8. 8

46. 2

69. 3

1. 7

6. 8

6.0

14 5

1. 3

. 1

. 1

3. 0

4 5

3.9

4. 1

12. 9

24 1

45. 0

66. 2

14 8

42. 8

212. 1

335. 9

1.7

1. 1

4 4

11. 1

18. 3

2. 6

2.9

8. 2

18. 1

31. 8

0.4

. 1

. 3

1. 0

1.8

49.7

14 0

38. 7

125.6

228. 0

217

140

340

1005

1702

Weight percent

Deep oceanic-__-_--

Young folded belts- _ _

All sediments __ _____ __

28. 5

60. 6

51. 9

43. 2

44 5

0 4

4

5

7

6

8. 1

8. 9

11. 4

11. 6

10. 9

5.0

2. 4

2. 6

4.6

4 0

1. 2

2.0

.6

.9

0.6

. 3

.3

1. 8

9 Q

3. 8

2. 4

2.6

30. 5

10.6

12. 6

91 1

19.7

0.8

.8

1. 3

1. 1

1. 1

1.2

2. 1

2. 4

1.8

1.9

0.2

. 1

. 1

. 1

. 1

22. 9

10.0

11. 4

12. 5

13. 4

100

100

100

100

100

average composition of the shield sediment is computed 

by using a ratio of 41:43:16 of shale, sandstone and 

limestone, respectively, and by using the average analyses of these sediments (Clarke and Washington, 1924). 

Similarly, the average composition of sediment in the 

young folded-belts region is computed by using the 

ratios of 52, shale: 13, sandstone: 22, limestone: 5, graywacke: 6, andesite: 2, rhyolite. Because of the abundance of crystalline rocks at the surface in the foldedbelts region, the volume of sediments is considered to 

be only 60 percent of the upper 5-km-thick shell in this 

region.

Most of the continental crust consists of crystalline 

rocks which are generally agreed to be more silicic at 

the surface than at depth. An average composition for 

shield crystalline rocks is derived by averaging (1) the 

averages for the Finnish Precambrian (probably too 

silicic; Sederholm, 1925) and the Canadian Precambrian (probably too mafic; Grout, 1938), (2) a mixture 

of quartzo-feldspathic gneiss and amphibolite in the 

proportions 5:1, (3) the average plutonic rock of Vogt 

(1931), and (4) Nockolds' (1954) average granodiorite. From the assumption that the crust is in isostatic 

adjustment, materials of increasing density and mafic 

composition are assumed in depth to the Mohorovicic 

discontinuity. According to Poldervaart's schematic 

cross section, the average composition and approximate 

thicknesses are granodiorite, 22 km; diorite, 3 km; 

and basalt, 10.5 km. Presumably the basalt includes 

both tholeiitic and olivine-bearing types, but their relative proportions are not given.

The young folded-belts region contains material with 

average composition and thickness as estimated from 

Poldervaart's schematic section: granodiorite, 22.5 km; 

diorite, 2.7 km; and basalt, 7.3 km (both tholeiite and 

olivine basalt, but not specified as to relative proportions) . Also 40 percent of the 5-km-thick surface layer 

is considered granodioritic, according to the abundance 

of surface outcrops of such batholithic rocks. Included 

with the continental crust are volcanic islands of the 

oceanic regions totaling about 2X106 km2 in area and 

considered to consist of 4 km andesite, 4% km tholeiitic 

basalt, and 6 km olivine basalt.

The composition of the whole lithosphere in terms 

of the major elements is summarized in table 15.

Pakiser and Robinson (1967) divided the conterminous United States into 10 regions on the basis of 

seismic structure and further grouped 7 western and 

3 eastern regions into a western and an eastern superprovince. Two distinct layers of the crust were distinguished from seismic velocity data (upper layer, 5.8- 

6.4 km per sec; lower layer, generally 6.7-7.5 km per 

sec) and formed the basis for computation of the volume of the crust under the regions and superprovinces. 

Seismic velocities in the crust, correlated with rock composition from recent laboratory experiments, were 

found to be appropriate for rocks of mafic composition 

in the lower layer and for rocks of silicic composition 

in the upper layer, and rocks of these general compositions were assumed to constitute the crust. Using the 

average compositions of mafic and silicic rocks of Nockolds (1954), these authors computed the average composition of the crustal layers and the crust beneath the 

seismic regions, the superprovinces and the entire conterminous United States. These computations are summarized in tables 16 and 17.

The average composition of the crust computed by 

Pakiser and Robinson is similar to that computed by 

Poldervaart; although the former authors found the 

Western superprovince slightly more siliceous than the 

analogous crust of Poldervaart (young folded-belts
D10 DATA OF GEOCHEMISTRY

region) and found the Eastern superprovin.ee to be 

more mafic than his continental shields region. These 

differences arise from new seismic results showing that

the crust is thinner and more silicic in tectonically active regions than in stable regions, rather than the reverse relation as assumed by Poldervaart.

TABLE 15. Composition of the lithosphere 

[Modified from Poldervaart (1955, table 20)]

SiOa TiOz AlzOj FejOj FeO MnO MgO CaO Na20 KS O PsO, Total Percent

Mass composition (X101* tons)

Sediments __ _

Granodiorite * _ _ _ _ _

Granodiorite _-----

Diorite. ________ _

Tholeiite _____ _

Olivine basalt. _ _ __

Lithosphere_____ _

757.3

4, 141. 5

1, 765. 9

12.5

1, 182. 7

1, 342. 7

3, 851. 4

13, 054 0

10. 2

37.4

1Q 8

.3

33.9

36.8

246. 4

3848

185. 4

966.7

AK() ()

4 0

372.4

410.7

1, 240. 0

3, 629. 2

69.3

112.3

S4 Q

.8

60.9

28.9

303.9

661. 0

14 5

1746

93.4

1 3

158. 0

258. 1

681.6

1, 381. 5

4 5

6. 2

5.7

45

5.3

16. 4

42.6

45. 0

124 7

849

1. 0

137.7

1844

656.9

1, 234 6

335.9

237. 0

1443

1.8

191. 8

276.5

895. 1

2, 082. 4

18.3

218.3

96.2

. 9

76.7

57.9

213. 5

681. 8

31.8

205.8

76.4

. 3

29. 4

26. 3

82. 1

452. 1

1.8

12. 5

8. 5

. 1

9.0

5.4

24.7

62. 0

1,474

6,237

2,830

23

2,257

2,633

8,212

23, 666

6.2

26.3

12 0

9.6

11. 1

348

100. 0

Weight percent

Oceanic region ____

Suboceanic region. _

Young foldedbelts region, ____

Continental shield

region__________

Lithosphere_____ _

Continental crust 

average-young

folded-belts and

continental

shield regions _ _

46. 6

49. 4

58. 4

59.8

55. 2

59. 4

2.9

1. 9

1. 1

1.2

1. 6

1. 2

15.0

15. 1

15. 6

15.5

15. 3

15.6

3.8

3.4

2.8

2. 1

2.8

2.3

8. 0

6.4

4 8

5. 1

5.8

5.0

0.2

. 2

.2

. 1

. 2

. 1

7.8

6.2

43

4. 1

5.2

42

11.9

13.2

7.2

6.4

8.8

6.6

2.5

2.5

3.1

3. 1

2.9

a i

1.0

1.3

2.2

2.4

1.9

2.3

0.3

.3

.3

. 2

.3

.2

i Continental shield region. 

»Young folded-belts region.

MINOR ELEMENTS

The minor elements form a relatively insignificant 

proportion of the earth's crust when compared to the 

major elements. This fact is well illustrated in table 18 

in which the 25 most abundant elements are listed in 

terms of their weight percentages in the crust. Accordingly, the 10 most abundant elements comprise 99.17 

percent of the crust, whereas the 15 next most abundant 

elements make up only 0.556 percent. Thus an even 

smaller percentage remains for the 67 other elements. 

Relative abundances of the elements, in which the magnitude of abundance is plotted against atomic number, 

are shown graphically in figure 3.

The abundance of some minor elements is well known

from much work on specific rocks and groups of rocks 

during the last 20 years; however, the abundance of 

others is still poorly known. Abundance tables based 

on these data are, therefore, variable as to accuracy and 

completeness among these elements listed, and such 

tables are being revised constantly as modern data are 

accumulated. Many recent studies of the abundances 

of specific elements are reviewed and cited in the summaries of Turekian and Wedepohl (1961), Vinogradov 

(1962), and Taylor (1964) and need not be discussed 

further here. The abundance of elements, both minor 

and major, in various igneous and sedimentary rocks 

listed in the tables of Turekian and Wedepohl (1961) 

and Vinogradov (1962) are assembled in table 19.
COMPOSITION OF THE EARTH'S CRUST Dll

TABLE 16. Proportions of major crustal units 

[Computed by Pakiser and Robinson (1967)]

Region

Area 

(km2 x 1(H)

Silicic crust

Thickness 

(km)

Volume 

(km3 x 1(H)

Mafic crust

Thickness 

(km)

Volume (km" x 10-*)

Total crust

Volume 

(km3 x 1<H)

Mafic rocks

Volume 

percent

Weight 

percent 1

Western superprovince

California coastal region. _ _ __ ______

Sierra Nevada _______________ _ ___ _ _

Pacific Northwest coastal region _ _ _ _

Basin and Range province __._ ___

Colorado Plateaus __-_ __ _ ____

Rocky Mountains _ __________

Subtotal _ _

43

7

29

30

121

34

61

325

15

25

10

10

20

25

25

2 10

645

175

290

300

2,420

850

1,525

6,205

5

25

25

35

10

15

15

2 15

215

175

725

1,050

1,210

510

915

4,800

860

350

1, 015

1,350

3,630

1,360

2, 440

11, 005

25. 0

50. 0

71.4

77.7

33.3

37. 5

37.5

43.6

26.3

51.7

72.8

78.8

34.8

39. 1

39. 1

45. 3

Eastern superprovince

Interior Plains and Highlands _______

Coastal Plain. _ ______ ___ _ ___ __

Appalachian Highlands and Superior UplandSubtotal. _ _____ ______

Continental crust, conterminous United 

States: 

Total _ _ _ _______ _ -_ .._ -

358

154

162

674

999

20

20

15

2 19

2 1Q

7, 160

3, 080

2,430

12, 670

18, 875

30

15

25

2 25

2 22

10, 740

2,310

4,050

17, 100

21, 900

17, 900

5,390

6,480

29, 770

40, 775

60. 0

42.8

62. 5

57. 4

53.7

61.6

44. 4

64.2

59.2

55. 4

1 Average weight percent of mafic rocks based on average densities of 2.8 g per 

cms and 3.0 g per cm^ for silicic crust and mafic crust, respectively. 

Average thicknesses of total crust: 

Western superprovince, 34 km;

2 Average thickness of total crust Continued 

Eastern superprovince, 44 km. 

All regions, 41 km.

TABLE 17. Estimates of abundance of major oxides in continental crust, by Pakiser and Robinson, and other estimates for comparison

Oxides

Si02 ---------------

Ti02 ____-_-_-----__-

A12 03 --------------

Fe2 O3 ------------

FeO --------------

MnO ._ -_-_-_-_-_-_

MgO _- - _

CaO____. 

Na_O--_ --------------

K2 0____ --------------

P2 05 ___-. ------------

Total ___ -- _ .

Pakiser and Robinson (1967)

Silicic 

rocks i

69.3 

0. 5 

146 

1. 7 

2. 2 

0. 1 

1. 1 

2. 6 

3.9 

3. 8 

0.2

100. 0

Mafic 

rocks i

48.8 

1.8 

15. 6 

2. 8 

8.2 

0.2 

8.7 

10. 8 

2.3 

0.7 

0. 3

100. 2

Western 

superprovince 2

60. 0 

1. 1 

15. 1 

2. 3 

4. 9 

0. 1 

4. 5 

6.3 

3. 2 

2.4 

0.2

100. 1

Eastern 

superprovince 2

57. 1 

1.3 

15.2 

2.3 

5.7 

0.2 

5. 6 

7.5 

3. 0 

2. 0 

0.3

100. 2

Continental 

crust 2

57.9 

1.2 

15. 2 

2.3 

5. 5 

0.2 

5.3 

7. 1 

3. 0 

2. 1 

0.3

100. 1

Other estimates

Continental 

crust 3

60. 3 

1. 0 

15. 6

(6) 

6 7. 2 

7 0. 1 

3. 9 

5.8 

3.2 

2. 5 

7 0.2

99.8

Continental 

crust *

63. 1 

0.8 

15. 2

(6) 

66. 0 

7 0. 1 

3. 1 

4. 1 

3.4 

3. 0 

7 0. 2

99. 0

Young 

folded 

belts «

58. 4 

1. 1 

15. 6 

2.8 

4 8 

0. 2 

4.3 

7. 2 

3. 1 

2.2 

0.3

100. 0

Continental 

shield «

59.8 

1. 2 

15. 5 

2. 1 

5. 1 

0. 1 

4 1 

6. 4 

3. 1 

2.4 

0.2

100. 0

1 Nockolds' (19S4) averages of 794 silicic igneous rocks and 637 mafic igneous rocks.

2 Based on weight percent of mafic crust from Pakiser and Robinson (1967) and 

Nockolds' (19S4) averages. 

8 Taylor's (1964) averages based on 1 part mafic and 1 part silicic rocks.

* Vinogradov's (1962) averages based on 1 part mafic and 2 parts silicic rocks. 

' Poldervaart's (1955) averages based on assumed crustal models. 

' Total Fe expressed as FeO. 

' Estimated to complete table.
PERCENT WEIGHT IN ABUNDANCE, 

VIVO iHJLSD\[3HOQ39
COMPOSITION OF THE EARTH'S CRUST D13

TABLE 18. Weight percentages of 25 of the most abundant elements 

of the earth's crust

Rank Element

[Data from Mason (1958, p. 44)]

Weight 

percent

1. Oxygen____________ 46.60

2. Silicon.._ ....__.. 27.72

3. Aluminum _______ 8.13

4. Iron______________ 5.00

5. Calcium___________ 3.63

6. Sodium........______.. 2.83

7. Potassium__________ 2.59

8. Magnesium__________ 2.09

9. Titanium._________.. .44

10. Hydrogen ________ .14

Total of first 10____ 99.17

11. Phosphorus__________ .118

12. Manganese-_________ .100

13. Fluorine.___________ .070

Rank Element

14. 

15. 

16. 

17.

18. 

19. 

20. 

21. 

22. 

23. 

24. 

25.

Nickel. 

i. Total of all 25 

Weight 

percent

 .052

 - .045

..... .040

_ - .032

 .020

 .020

_ - .016

 .012

 .011

 - .008

 .007

 .. .005

 . 99.726

Estimates of the abundance of minor elements in the 

earth's crust have been compiled by different authors for 

many years. Some of the principal works that serve 

to show the accumulation of data and improvements 

in their accuracy and completeness are Clarke and 

Washington (1924), Goldschmidt (1937), Fleischer 

(1953), Eankama (1954), Mason (1952, 1958), Vinogradov (1962), and Taylor (1964). Tabulations by 

these authors for the abundance of elements in the 

crust, or parts thereof, are assembled in table 20.

TABLE 19. Abundance of elements in certain types of rocks 

[T and W, data from Turekian and Wedepohl (1961); V, data from Vlnogradov (1962)]

]

Atomic 

No.

Element

Ultramafic 

rocks

(Tand 

W)

(V)

Percent Code 

1 -9 _ ______ - -X

.1 -.9 

.01 -.0 

.001-. 0

. __ .... ___ . ____________ .... ______ ....... _ ._.... ......X

9... ___________________________________ ..OX 09 . __ ..... _ . ________________ . _ . _ . _ ...OOX

Basalts

(Tand 

W)

(V)

Intermediate 

rocks 

(V)

Felsic 

granites 

and 

granodiorites 

(V)

Granites 

(T and W)

High 

calcium

Low 

calcium

Syenites 

(Tand 

W)

Clays 

and 

shales 

(V)

Shales 

(Tand 

W)

Sandstones 

(Tand 

W)

Carbonate rocks 

(Tand 

W)

Deep-sea carbonate rocks 

(Tand 

W)

Deep-sea 

clays 

(Tand 

W)

Weight percent

1

8

11

12

13

14

15

19

20

22

25

26

Titanium... .....

.42

20.40

2

20.50

.022

.004

2.5

.03

.162

9.43

42.5

.57

25.90

.45

19

.017

.03

.7

.03

.15

9.85

1.80

4.60

7.80

23

.11

.83

7.6

1.38

.15

8.65

43.5

1.94

4.5

8.76

24

.14

.83

6.72

.9

.2

8.56

46

3

2.18

8.85

26

.16

2.3

4.65

.8

.12

5.85

48.7

2.77

.56

7.7

32.3

.07

3.34

1.58

.23

.06

2.7

2.84

.94

8.20

31.40

.092

2.52

2.53

.34

.054

2.96

2.58

.16

7.20

34.70

.06

4.20

.51

.12

.039

1.42

4.04

.58

8.80

29.10

.08

4.80

1.80

.35

.085

3.67

52.8

.66

1.34

10.45

23.8

.077

2.28

2.53

.45

.067

3.33

.96

1.50

8

7.30

.07

2.66

2.21

.46

.085

4.72

.33

.70

2.50

36.80

.017

1.07

3.91

.15

.OOX

.98

.04

4.70

.42

2.40

.04

.27

30.23

.04

.11

.38

2

.40

2

3.20

.035

.29

31.24

.077

.10

.90

4

2.10

8.40

25

.15

2.50

2.90

.46

.67

6.50

Parts per million

2

3

4

5

6

7

9

10

16

17

18

21

23

24

27

28

29

30

31

32 

33

34

35

37

38

39

40

41

42 

43

44

45

47

48

49

50

51

52

53

54

Lithium .........

Beryllium .......

Chromium. .....

Nickel 

Germanium. _ .

Bromine ____

Yttrium.........

Molybdenum. ..

Silver ...........

TndiiiTn

Tin. _ . ......

Xenon ____ ..

.X

.X

3

6

100

300

85

15

40

1600 

150

2000

10

50

1.5

1.5 

1

.05

1

.2

1

.X

45

16

.3

12

.06

.X

.01

.5

.1

.5

.5

.2

1

100

6

100

100

50

5

40

2000 

200

2000

20

30

2

1

.5

.05

.5

2

10

30

1

.2

19

.05

.05

.013

.5

.1

001

.01

17

1

5

20

400

300

60

30

250

170 

48

130

87

105

17

1.3

2

.05

3.6

30

465

21

140

19

1.5

.02

.11

.22

.22

1.5

.2

.5

15

.4

5

100

1 Q

370

300

50

24

200

200 

45

160

100

130

18

1.5 

2

.05

3

45

440

20

100

20

1.4

mo

.1

.19

.22

1.5

1

nm

.5

20

1.8

15

200

00

500

9fifi

100

2.5

100

50 

10

55

35

79

20

1.5 

2.4

.05

4.5

100

800

260

20

.9

.07

.2

nm

.3

40

5.5

15

300

20

800

400

240

3

40

25

5

8

20

60

20

1.4 

1.5

.05

1.7

200

300

34

200

20

1

.01

.05

.1

.26

3

.26

001

.4

24

2

9

9ft

520

300

130

14

88

22

7

15

30

60

17

1.3 

1.9

.05

4.5

110

440

35

140

20

1

finv

.051

.13

.OX

1.5

.2

.5

40

3

10

9fi

850

300

200

7

44

4.1 

1

4.5

10

39

17

1.3

1.5

.05

1.3

170

100

40

175

21

1.3

ftftV

.037

.13

.26

3

.2

.5

28

1

9

30

1200

300

520

3

30

2 

1

4

5

130

30

1 

1.4

.05

2.7

110

200

20

500

35

.6

.OX

.13

.OX

X

.X

.5

60

3

100

10000

600

500

3000

160

10

130

100 

20

95

57

80

30

2 

6.6

.6

6

200

450

30

200

20

2

.1

.3

.05

10

2

.01

1

66

3

100

740

2400

180

13

130

90 

19

68

45

95

19

1.6 

13

.6

4

140

300

26

160

11

2.6

.07

.3

.1

6

1.5

2.2

15

.X

35

270

240

10

1

20

35 

.3

2

X

16

12

.8 

1

.05

1

60

20

40

220

.OX

.2

.OX

.OX

.ox

.X

.ox

1.7

5

.X

20

330

1200

150

1

20

11 

.1

20

4

20

4

.2 

1

.08

6.2

3

610

30

19

.3

.4

.OX

.035

.OX

.X

.2

1.2

5

.X

55

540

1300

21000

2

20

11

7

30

30

35

13

.2 

1

.17

70

10

2000

42

20

4.6

3

.OX

.ox

.ox

.X

.15

.05

57

2.6

230

1300

1300

21000

19

120

90 

74

225

250

165

20

2 

13

.17

70

100

180

90

150

14

27

.11

.42

.08

1.5

1

.05
D14 DATA OF GEOCHEMISTRY

TABLE 19. Abundance of elements in certain types of rocks Continued

Atomic 

No.

Element

Ultramafic 

rocks

(T and 

W)

(V)

Basalts

(Tand 

W)

(V)

Intermediate 

rocks 

(V)

Felsic 

granites 

and 

granodiorites 

(V)

Granites 

(T and W)

High 

calcium

Low 

calcium

Syenites 

(Tand 

W)

Clays 

and 

shales 

(V)

Shales 

(Tand 

W)

Sandstones 

(Tand 

W)

Carbon 

ate rocks 

(Tand 

W)

Deep-sea carbonate rocks 

(Tand 

W)

Deep-sea 

clays 

(Tand 

W)

Parts per million Continued

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

72

73

74

75

76

77

78

79

80

81

82

83

84

85

86

87

88

89

90

91

92

Barium ..........

Lanthanum.

Neodymium _____

Europium.. ....

Gadolinium __

Terbium ____

Dysprosium _____

Erbium... ______

Thulium _ ___

Lutetium __ ._

Rhenium.. _. ._

Osmium ___ .

Iridium..... __

Gold.... .. .__

Thallium.. ______

Lead _. ._____.

Bismuth ____

Thorium ________

.X

.4

.X

.X

.X

.X

.X

.X

.X

.X

.X

.X

.X

.X

.X

.X

.6 1

.77

.006

.OX

OR

1

.004

.001

.1

1

.01

.05

.018

.1

2

.005

.01

.01

.1

.001

.005

003

1.1

330

15

48

4.6

20

5.3

.8

5.3

.8

3.8

1.1

2.1

.2

2.1

.6

1.1

.7

.004

.09

01

6

.007

4

1

1

300

27

AK

4

20

5

1

5

2

1

2

.2

.6

1

AQ

1

. 00071

.1

.004

.09

.2

8

.007

3

650

1

1

.5

15

.01

.01

7

i s

.5

QOfl

60

100

19

46

1.5

9

2

e

6.7

.3

4

1

1

3

C

1.5

. 00067

0063

.0045

no

1 1

20

.01

18

0 K

420

45

Q1

7.7

33

8.8

1.4

8.8

1.4

6.3

1.8

3.5

.3

3.5

1.1

2

0

3 ft

1 3

Oft-t

.08

70

If.

8.5

S4.0

55

Q9

8.8

37

10

1.6

10

1.6

7.2

.3

1.2

5 Q

4 9

2 2

nru

.08

2

O

1Q

.01

17

.6

1600

70

161

15

65

18

2.8

18

2.8

13

3.5

.6

2.1

11

2.1

1 3

.oox

.ox

1.4

12

13

3

12

800

40

50

5

23

6.5

1

6.5

.9

4.5

1

2.5

.25

3

6

3.5

.001

.4

1

20

.01

11

3.2

5

580

92

59

5.6

24

6.4

1

6.4

1

4.6

1.2

2.5

.2

2.6

.7

2.8

.8

1.8

.OOX

.4

1.4

20

12

3.7

.X

xo

30

92

8.8

37

10

1.6

10

1.6

7.2

2

4

.3

4

1.2

3.9

.OX

1.5

.OOX

.03

.82

7

1.7

.45

.X

10

X

11.5

1.1

4.7

1.3

.2

1.3

.2

.9

.3

.5

.04

.5

.2

.3

.OX

.6

.OOX

.04

.OX

9

1.7

2.2

.4

190

10

35

3.3

14

3.8

.6

3.8

.6

2.7

.8

1.5

.1

1.5

.5

.41

.OX

.X

.OOX

.ox

.16

9

X

.X

6

2300

115

345

33

140

38

6

38

6

27

7.5

15

1.2

15

4.5

4.1

.X

X

.OOX

.X

.8

80

7

1.3

PROBLEMS IN ESTIMATION OF ELEMENT ABUNDANCE

Some of the problems in the estimation of the abundance of elements, both in specific types of rocks and in 

the crust of the earth, are outlined by Fleischer and 

Chao (1960). These problems indicate some of the 

limitations and weaknesses imposed on abundance data, 

not only from the analytical standpoint, but from the 

standpoint of compilation and interpretation as well.

ABUNDANCE IN SPECIFIC BOCKS

The estimation of abundance in specific rock types is 

affected by the availability of analytical data, adequacy 

of sampling, and accuracy of results of analytical procedures. In recent years the analysis of rock samples 

for minor elements by X-ray fluorescence and optical 

spectrographic methods, in addition to routine analysis 

for the major elements, has added a wealth of data over 

the entire spectrum of rock compositions. Elements 

usually determined are barium, beryllium, cobalt, copper, chromium, gallium, molybdenum, nickel, lead, scandium, strontium, vanadium, and zirconium. In addition many analyses give data for silver, boron, lanthanum, lithium, niobium, rubidium, tin, yttrium, and 

ytterbium. Nevertheless, some elements in ordinary 

rocks exist below the threshold of detection by most

analytical methods, and unless special preenrichment 

techniques or special analytical techniques are used, 

these elements are not determinable. Tantalum, indium, germanium, rhenium, and some platinum metals 

belong to this group. Some of these elements are 

amenable to detection by activation analyses of various 

types, but most laboratories at the present time do not 

have ready access to special isotope-activated instruments or atomic reactors. Such elements, because of 

analytical difficulty, are not determined routinely; 

therefore, far fewer analyses exist for these elements 

than for the more easily determined elements.

The adequacy of sampling varies from element to 

element and depends on the number of determinations, 

the scope of the sampling, the description of the samples, and the petrologic classification of the samples. 

Hundreds of determinations are available for elements 

such as zirconium and gallium, whereas few exist for 

such elements as tellurium and bismuth. Some elements have been adequately analyzed in only a few 

types of rocks and geographic areas, greatly limiting 

our knowledge of their occurrence and regional distribution. Some analyzed samples have been so incompletely described as to leave doubt as to the petrologic 

classification of the sample, or whether the sample is
COMPOSITION OF THE EARTH'S CRUST D15

TABLE 20. Abundance of elements in the earth's crust and in igneous rocks

Percent Code

1 -9 .....

.1 -.9..... 

.01 -.09.... 

.001 -.009... 

.0001 - .0009.. 

. 00001- . 00009.

X

.X

.ox 

.oox

.OOOX 

. OOOOX

Atomic No.

Element

Continental 

crust i

Taylor 

(1964)

Earth's 

crust 3

Vinogradov 

(1962)

Earth's 

crust

Mason 

(1958)

Igneous rocks

Rankama 

(1954)

Goldschmidt 

(1937)

Clarke 

and Washington 

(1924)

Weight percent

1 

8 

11 

12 

13 

14 

15 

19 

20 

22 

25 

26

Magnesium....

Silicon. ........

Phosphorus.. 

Manganese _ ..

46.4 

2.36 

2.33 

8.23 

28.15 

.105 

2.09 

4.15 

.57 

.095 

5.63

47 

2.50 

1.87 

8.05 

29.5 

.093 

2.5 

2.96 

.45 

.10 

4.65

0.14

46.6 

2.83 

2.09 

8.13 

27.72 

.118 

2.59 

3.63 

.44 

.10 

5

46.6 

2.83 

2.09 

8.13 

27.72 

.118 

2.59 

3.63 

.44 

.10 

5

46.6 

2.83 

2.09 

8.13 

27.72 

.08 

2.59 

3.63 

.44 

.10 

5

0.13 

46.59 

2.85 

2.09 

8.13 

27.72 

.13 

2.60 

3.63 

.63 

.10 

5.01

Parts per million

2 

3 

4 

5 

6 

7 

9 

10 

16 

17 

18 

21 

23 

24 

27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

37 

38 

39 

40 

41 

42 

43 

44

Chlorine...- 

Chromium _

Nickel.... 

Zinc ___ ..

Gallium.... ....

Germanium....

Molybdenum..

20 

2.8 

10 

200 

20 

625

260 

130

22 

135 

100 

25 

75 

55 

70 

15 

1.5 

1.8 

.05 

2.5

90 

375 

33 

165 

20 

1.5

32 

3.8 

12 

230 

19 

660

470 

170

10 

90 

83 

18 

58 

47 

83 

19 

1.4 

1.7 

.05 

2.1

150 

340 

29 

170 

20 

1.1

0.003 

30 

2 

3 

320 

46 

700

520 

200 

.04 

5 

110 

200 

23 

80 

45 

65 

15 

2 

2 

.09 

3

120 

450 

40 

160 

24 

1

.001

0.003 

22 

2 

3 

320 

46.3 

700 

.00007 

520 

314 

.04 

20 

150 

200 

23 

80 

55 

111 

16 

7 

5 

.09 

1.62

350 

220 

28.1 

185 

24 

2.5

65 

6 

3 

320

300

520 

480

5 

150 

200 

40 

100 

100 

40 

15 

7 

5 

.09

310 

150 

28.1 

220 

20 

1.5

40 

10 

10 

320

300

520 

480 

X 

.X 

170 

370 

10 

200 

100 

40 

.OOOOX 

.OOOOX 

X

.ox

X

X

190 

H50 

260 

<30 

X

. OOOOX

Atomic No.

Element

Continental 

crust !

Taylor 

(1964)

Earth's 

crust 2

Vinogradov 

(1962)

Earth's 

crust

Mason 

(1958)

Igneous rocks

Rankama 

(1954)

Goldschmidt 

(1937)

Clarke 

and 

Washington 

(1924)

Parts per million Continued

45 

46 

47 

48 

49 

50 

51 

52 

53 

54 

55 

56 

57 

58 

59 

60 

61 

62 

63 

64 

65 

66 

67 

68 

69 

70 

71 

72 

73 

74 

75 

76 

77 

78 

79 

80 

81 

82 

83 

84 

85 

86 

87 

88 

89 

90 

91 

92

Rhodium. .... .

Silver.... ......

Tin

Iodine

Cesium.... _ . 

Barium.... __

Lanthanum ....

Cerium.... .. 

Praseodymium. 

Neodymium. . .

Promethium...

Europium ......

Gadolinium ....

Dysprosium ....

Thulium. _ _ Ytterbium.. ...

Gold 

Thallium. 

Thorium __ __

.07 

.2 

.1 

2 

.2

.5

3

425 

30 

60 

8.2 

28

6 

1.2 

5.4 

.9 

3 

1.2 

2.8 

.48 

3 

.5 

3 

2 

1.5

.004 

.08 

.45 

12.5 

.17

9.6

2.7

.013 

.07 

.13 

.25 

2.5 

.5 

.001 

.4

3.7 

650 

29 

70 

9 

37

8 

1.3 

8 

4.3 

5 

1.7 

3.3 

.27 

.33 

.8 

1 

2.5 

1.3 

.0007

.0043 

.083 

1 

16 

.009

13

2.5

.001 

.01 

.1 

.2 

.1 

3 

.2 

.002 

.3

1 

400 

18 

46 

6 

24

7 

1 

6 

.9 

5 

1 

3 

.2 

3 

.8 

5 

2 

1 

.001 

.001

.001 

.005 

.005 

.5 

1 

15 

.2

10

2

.001 

.01 

.1 

.15 

.11 

40 

1(?) 

.0018(7) 

.3

6 

1000 

18.3 

46.1 

5.53 

23.9

6.47 

1.06 

6.36 

.91 

4.47 

1.15 

2.47 

.20 

2.66 

.75 

4.5 

2.1 

1.5 

.05

.001 

.005 

.005 

.077 

1.3 

15 

.2 

3X10-10

1.3X10-8

3X10-10 

11.5 

8X10-' 

4

.001 

.01 

.1 

.5 

.1 

40 

1 

.0018(?) 

.3

7 

250 

18.3 

46.1 

5.53 

23.9

6.47 

1.06 

6.36 

.91 

4.47 

1.15 

2.47 

.20 

2.66 

.75 

4.5 

16(?) 

69 

.001

.001 

.005 

.005 

.5 

.3 

16 

.2 

3X10-10

1.3X10-6 

3X10-1" 

12 

8X10-7 

4

.OOOOX 

. OOOOX 

.OX 

.X 

. OOOOX 

X 

.X

.oox

.X

.X

500

30

50

.OOOX 

.OOOX 

.OOX

.oox

.X

.OOOX 

20

.ox

xxio-o

20

80

i Average 1 part mafic and 1 part felsic rocks. 

* Average 1 part mafic and 2 parts felsic rocks.

representative. Fortunately these undesirable trends 

are being stemmed in modern studies.

The accuracy of analyses is a factor that is difficult 

to assess. Some progress toward standardization among 

laboratories has been made by using standard samples. 

The fact that some laboratories produce analyses of 

high precision does not necessarily mean their analyses 

are of high accuracy, as has been pointed out by Ahrens 

(1957). Two rocks granite G-l from Westerly, R.I., 

and diabase W-l from Centerville, Va. were submitted 

to different laboratories to obtain comparative results 

(Fairbairn and others, 1951). The results showed serious disagreement among different laboratories, the disclosure of which has led to considerable improvement

 Yttrium plus cerium plus all other rare-earth elements. 

4 Niobium plus tantalum.

in techniques and accuracy. The results of analyses of 

these standards have been summarized by Ahrens and 

Fleischer (1960), Fleischer and Stevens (1962), and 

Fleischer (1965). Differences in the dependability of 

the analytical results are exemplified by data on zirconium and strontium, for which selected determinations by major laboratories are listed in table 21.

The results for zirconium are in close agreement, only 

5 of 24 determinations falling outside the range 210 ±30 

ppm. The results for strontium, however, are considerably divergent in the group done prior to 1951, 

and even those since 1954 range from 200 to 350 ppm. 

Such variations in determinations must be considered 

in establishing or interpreting abundance figures.
D16 DATA OF GEOCHEMISTRY

TABLE 21. Selected determinations of zirconium and strontium 

in granite G-l

Year 

reported

1951

1954

1955

1956

1957

1968

1961

1963

1964

1965

Method used

Chemical ____

Spectrographic - 

.... . do.. .. ........

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

. .do.. ..........

.....do.. ..........

.....do............

 do..... 

.... .do... .._......

X-ray fluorescence. 

Spectrographic ....

. __ do.. ____ ..

Colorimetric ......

Spectrographic - 

 do............

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

. .do...... ....

 ..do.... .

cence. 

Spectrographic _

.... .do. .........

 .do.. .

Flame photometer.

 ..do............

Spectrographic _ 

..... do............

 ..do............

X-ray fluorescence, 

 do.-.-.... ..

..... do.............

Zirconium 

(ppm)

200

280 

200

190

180

130

200

220

162

200

220 

200

180

190

213

233

230

250

210 

185

155

220 

214

239

Strontium 

(ppm)

450

250 

900

120

200

280

225

233

218

262

252

200

250

300

350

270

307

262 

250

265 

271

265

Name of laboratory

British Museum of Natural

History, London. 

Massachusetts Inst. Technology, Cambridge, Mass. 

Macauley Inst. Soil Research,

Aberdeen, Scotland. 

U.S. Geol. Survey, Washington, B.C. 

Great Britain Geol. Survey.

Cambridge Univ., England.

McMaster Univ., Hamilton,

Ontario. 

Columbia Univ., New York.

U.S. Geol. Survey, Denver,

Colo. 

Massachusetts Inst. Technology* Cambridge, Mass. 

Queen's Univ., Kingston,

Ontario. 

Columbia Univ., New York.

Establishment, Harwell, 

England.

apolis. 

California Inst. Technology, 

Pasadena, Calif.

Bloomington, tnd. 

Yale Univ., New Haven,

Conn.

Colo. 

McMaster Univ., Hamilton,

Ontario.

Sci. and Indus. Research 

Organization, Adelaide, 

Australia. 

McMaster Univ., Hamilton,

Ontario.

Div. Coal Research, Commonwealth Sci. and Indus. 

Research Organization, 

Chatswood, Australia. 

Vernadskii Inst., Moscow.

Pennsylvania State Univ., 

University Park, Pa.

Canberra, Australia.

Olso Univ., Norway.

ABUNDANCE IN THE CRUST

An accurate estimate of the abundance of elements 

in the crust requires an accurate knowledge of the proportions of specific rock types, their spatial distribution, and accurate analytical data on the concentration 

of the elements in these rocks. The works of Poldervaart (1955) and Pakiser and Robinson (1967) have 

come closest to this ideal, but even these outstanding 

works are limited to the few major elements. Furthermore the accuracy of computations are limited by the 

inadequate (?) geologic and chemical data available. 

It should be pointed out, however, that the average composition computed by Clarke and Washington (1924) 

corresponds rather closely with those of Poldervaart 

and Pakiser and Robinson even though the validity of 

the method of computing crustal composition of Clarke

and Washington has been the subject of considerable 

controversy and doubt.

Estimation of the abundance of some of the minor 

elements in the lithosphere is hampered not only by a 

lack of precise analytical data, but by the compilation 

methods that are employed as well. Many of these estimates are computed on the basis of ratios of certain 

minor elements to geochemically similar elements that 

are more easily determined analytically. Such ratios, 

however, for some elements have been shown to vary 

considerably among different rock types and comagmatic suites. Many abundance figures are established 

from averages of standard mafic and felsic rocks that 

are combined in various proportions to approximate 

the major element composition of the average crustal 

rock. The recent compilations by Vinogradov (1962) 

and Taylor (1964) are examples of this approach. 

Minor elements that are more or less uniformly distributed in the crust can be fairly accurately established 

by this method; however, those elements that are unequally distributed and are more abundant in or closely 

tied to certain types of rocks can be quite erroneously 

computed. Inasmuch as most of the standard rocks 

used for such computations are continental rocks, such 

averages cannot be truly said to represent the entire 

crust, including the more than half of the crust lying 

beneath the oceans.

Derivation of accurate crustal abundance figures for 

both major and minor elements is hampered by our limited knowledge of (1) the sediments and underlying 

rocks in the oceanic regions not exposed to direct observation, (2) the proportions of different rocks in the exposed areas of the earth, and especially (3) the actual 

distribution and composition of materials at depth, in 

the crust. As the wealth of geologic data accumulates, 

our knowledge of these factors can be expected to improve. The constantly increasing coverage of geologic 

mapping affords data for determining volumetric distribution and proportion of rocks through geologic interpretation and projection. Accelerated research in 

oceanography and geophysics is adding measurably to 

the data on the nature of the vast areas beneath the 

oceans and at depths within the crust.

REFERENCES

Ahrens, L. H., 1957, A survey of the quality of some of the 

principal abundance data of geochemistry, *» Ahrens, L. H., 

and others, eds., Physics and chemistry of the earth: New 

York, Pergamon Press, v. 2, p. 30-45.

Ahrens, L. H., and Fleischer, Michael, 1960, Report on trace 

constituents in granite G-l and diabase W-l, Part 4 of 

Second report on a cooperative investigation of the composition of two silicate rocks: U.S. Geol. Survey Bull. 1113, 

p. 83-111.
COMPOSITION OF THE EARTH'S CRUST D17

Birch, Francis, 1964, Density and composition of the mantle

and core: Jour. Geophys. Research, v. 69, no. 20, p. 4377-4388. 

Bucher, W. H., 1955, Deformation in erogenic belts, in Poldervaart, Arie, ed., Crust of the earth a symposium: Geol.

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Bullen, K. E., 1963, An introduction to the theory of seismology

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Clarke, F. W., 1889, The relative abundance of the chemical

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the earth's crust: U.S. Geol. Survey Prof. Paper 127,117 p.

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 1914, Igneous rocks and their origin: New York, McGrawHill Book Co., Inc., 563 p. 

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Grout, F. F., 1938, Petrographic and chemical data on the Canadian Shield: Jour. Geology, v. 46, p. 486-504.

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 1963, The rare earth contents of standard rocks G-l and 

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Knopf, Adolph, 1916, Composition of the average igneous rocks: 

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Loewinson-Lessing, Franz, 1911, The fundamental problems of 

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[Great Britain], new ser., decade 5, v. 8, p. 248-257.

Mason, Brian, 1952, Principles of geochemistry: New York, John 

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Nockolds, S. R., 1954, Average chemical compositions of some

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Pakiser, L. C., and Robinson, Rhoda, 1967, Composition of the

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p. 577-622. 

Sederholm, J. J., 1925, The average composition of the earth's

crust in Finland: Finlande Comm. G6ol. Bull., no. 70, 20 p. 

Taylor, S. R., 1964, The abundance of chemical elements in the

continental crust a new table: Geochim. et Cosmochim.

Acta, v. 28, p. 1273-1285.

 1965, Abundance of chemical elements in the continental

crust amended basaltic rare-earth patterns: Geochim. et

Cosmochim. Acta, v. 29, p. 145-146. 

Turekian, K. K., and Wedepohl, K. H., 1961, Distribution of the

elements in some major units of the earth's crust: Geol. Soc.

America Bull., v. 72, p. 175-192. 

Vinogradov, A. P., 1962, Average contents of chemical elements

in the principal types of igneous rocks of the earth's crust:

Geokhimiya 1962, no. 7, p. 555-571 (in Russian) ; translation

in Geochemistry, 1962, no. 7, p. 641-664. 

Vogt, J. H. L., 1931, On the average composition of the earth's

crust with particular reference to the contents of phosphoric

and titanic acid: Norske Vidensk.-Akad. Skr., Mat-Naturv.

KL, no. 7, p. 1-48. 

Washington, H. S., 1903, Chemical analyses of igneous rocks,

published from 1884 to 1900, with a critical discussion of the

character and use of analyses: U.S. Geol. Survey Prof.

Paper 14,495 p.

 1917, Chemical analyses of igneous rocks published from 

1884 to 1913, inclusive, with a critical discussion of the character and use of analyses a revision and expansion of Professional Paper 14: U.S. Geol. Survey Prof. Paper 99,1201 p.

Wickman, F. E., 1954, The "total" amount of sediments and the 

composition of the "average igneous rock": Geochim. et 

Cosmochim. Acta, v. 5, p. 97-110.
INDEX

[Italic page numbers indicate major references]

Page

Abundance, elements, earth's crust_______________________ D15

elements, igneous rocks____________________________ 15

major oxides..---_______________________________ 11

major rock-forming elements_________________________ 8,13

minor rock-forming elements________________________ 13

Abundance data, limitations___________________________ 14

Analyses, accuracy. ...__________________________ 15,16

techniques _.______________________________ 14

Appalachian region, igneous rock composition..._______________ 4

Basalt, average composition__________________________ 7 

Bullen, K. E., cited...__....._...____.___.__..._.._____ 1,2

Clarke, F. W., and Washington, H. S., cited__._______________ 3,4 

Compressional seismic waves. See Seismic waves.

Core. ______-_____________________________ 2 

Crust ____________________________________ 2

Daly, E. A., cited_________________________________ 5 

Density, earth___________________________________ 1,2 

Depth, seismic waves. See Seismic waves.

Earth, constitution-_______________________________ 1 

density. See Density; 

threefold division....___________________._______ 1

Earth shells, physical dimensions________________________ 2 

Elements, crustal, major __.._. ...._......._ __.... 3, 16

crustal, minor_________......._.____..._.____.__ /0,16

major rock forming .._ ........ ... 8

problems in estimation of abundance.. __ . ____ . 14

Fennoscandian ice sheet . . ....... 6

Finnish crust, average chemical composition...___.__....__...... 4

average rock composition_____..._.__._.... .._._..._. 4

Fleischer, Michael, cited -__... . - 12

Granite, average composition. 

Hemipelagic sediments...__

Igneous rock, average composition...___________ ___ 4,7 

Inner core, density. See Density.

Page

Lithosphere, composition___________________.____._ 9,10 

four structural divisions.. ______________ __. 8

Mantle______________________________________- 2 

Mason, Brian, cited__________._.__ 2,12,13

Mead, W. J., cited...-__....__....-__.__.__.__._____ 7 

Mead's equation _ ____...... ...._ ... 7

Mohorovifiic discontinuity-________...__.__ ... 1,2,8,9

Norwegian crust, plutonic rock composition._. 

Norwegian loams, average chemical composition.

P seismic waves. See Seismic waves.

Pacific Cordillera region, igneous rock composition 4 

Pakiser, L. C., and Robinson, Ehoda, cited._._ . . 11 

Pelagic sediments - 8 

Poldervaart, Arie, cited .. ... . 9,10

Rare-earth abundance patterns.

S seismic waves. See Seismic waves. 

Sampling, adequacy. . . 

Sediments, average composition . 

Seismic waves ____ _ _ . 

Shear seismic waves. See Seismic waves. 

Shelf sediments.. ___ _ . _ 

Sialma __ ___

Sima- .

Surface rocks, density. See Density.

Taylor, S. R., cited________... __ 

Turekian, K. K., and Wedepohl, K. H., citedVelocity, seismic waves. See Seismic waves. 

Vinogradov, A. P., cited .. . . . 

Vogt, J. H. L., cited __.._ _.

Waves. See Seismic waves. 

Wickman, F. E., cited................

Wiechert-Gutenberg discontinuity 

o

D19