Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL...

47
Shorter Contributions to General Geology 1958 GEOLOGICAL SURVEY PROFESSIONAL PAPER 334 This Professional Paper was published as separate chapters A H UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1962

Transcript of Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL...

Page 1: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

Shorter Contributions

to General Geology

1958

GEOLOGICAL SURVEY PROFESSIONAL PAPER 334

This Professional Paper was published

as separate chapters A H

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1962

Page 2: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

UNITED STATES DEPARTMENT OF THE INTERIOR

STEW ART L. UDALL, Secretary

GEOLOGICAL SURVEY

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U.S. Government Printing OfficeWashington 25, D.C.

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CONTENTS

[The letters in parentheses are those used to designate the separate chapters]Page

(A) Tables for the calculation of lead isotope ages, by L. R. Stieff, T. W. Stern, Seiki Oshiro, and F. E. Senftle_________ 1(B) Fossils of the Littleton formation (Lower Devonian) of New Hampshire, by A. J. Boucot and Robert Arndt_________. 41(C) Trilobites of the Upper Cambrian Dunderberg shale, Eureka district, Nevada, by Allison R. Palmer_ _-____-___-__-__ 53(D) Late Paleozoic Gastropoda from northern Alaska, by Ellis Y. Yochelson and J. Thomas Dutro, Jr___________________ 111(E) Upper Cretaceous Pelecypods of the genus Inoceramus from northern Alaska, by David L. Jones and George Gryc_____ 149(F) Ammonites of Early Cretaceous age (Valanginian and Hauterivian) from the Pacific Coast States, by Ralph W. Imlay_ 167 (G) Dispersion characteristics of montmorillonite,kaolinite, and illite clays in waters of varying quality, and their control

with phosphate dispersants, by B. N. Rolfe, R. F. Miller, and I. S. McQueen___________________________________ 229(H) Geology of southeastern Ventura basin, Los Angeles County, California, by E. L. Winterer and D. L. Durham________ 275

ni

U.S. GOVERNMENT PRINTING OFFICE : 1962 O -581734

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Tables for the Calculation

of Lead Isotope AgesBy L. R. STIEFF, T. W. STERN, SEIKI OSHIRO, and F. E. SENFTLE

SHORTER CONTRIBUTIONS TO GENERAL GEOLOG

GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A

Tables for the calculation of geologic age using the. .' r r>l206/TT238 DU207/TT23S D U 207 I r> U 206atomic ratios oj rb /U , rb /U , rb /rb ,

and Pb208 /Th 32. This report concerns work done on

behalf of the U. S. Atomic Energy Commission and

is published with the permission of the Commission

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1959

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UNITED STATES DEPARTMENT OF THE INTERIOR

FRED A. SEATON, Secretary

GEOLOGICAL SURVEY

Thomas B. Nolan, Director

The U. S. Geological Survey Library has cataloged this publication as follows:

Stieff, Lorin Roll ins, 1920-Tables for the calculation of lead isotope ages, by L. K.

Stieff f and others] Washington, U. S. Govt. Print. Off., 1959.

iv, 40 p. diagrs., tables. 30 cm. (U. S. Geological Survey. Pro­ fessional paper 334-A. Shorter contributions to general geology)

"Tables for the calculation of geologic age using the atomic ratios of Pb206/U238, Pb207/U235, Pb207/Pb206, and Pb208/Th232."

Bibliography: p. 7.1. Lead Isotopes. 2. Isotopes Tables, etc. 3. Geological time

i. Title. (Series: U. S. Geological Survey. Professional paper 334-A. Series: U. S. Geological Survey. Shorter contributions to general geology)

550.1

For sale by the Superintendent of Documents, U. S. Government Printing Office Washington 25, D. C. - Price 35 cents (paper copy)

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CONTENTS

Abstract-- _ __________________________Introduction ___________-_-_---_____-_Methods of computation--_____-_______

The Nd/Np relation.______________The Nw/Nm relation___.,._____.__

Sample age calculation________________Correction for original common lead.

Page 1 1 33456

Sample age calculation ContinuedPb2oe/U2»8 age method___.__________._.Pb207/U23B age method__________.__.__.Pb207/Pb206 age method..._______________Pbzos/Th232 age method_______-_____._.

Literature cited.________..-______--__-__-_Tables for the calculation of lead isotope ages.

ILLUSTRATIONS

Page

677779

FIGURE 1. Atomic ratio Nd/N p plotted against the age, t, showing the plus and minus tolerance curves.-. 2. Atomic ratio Nw,/Nm plotted against the age, t, showing the plus and minus tolerance curves.

TABLES

TABLE 1. Physical constants used in calculation of tables-__.______-_-___---__-_---__-__-2. Errors in t produced by uncertainties in the physical constants used in calculation.3. Range and interval of <_________.__.________-_______..______________________.4. Decay constants X,- (y-1).-_-_____._.___-_____-_-______-__-________-_-______-

m

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LETTER SYMBOLS

X decay constantt age, in millions of yearsT half lifeN number of atomsNd number of atoms of daughter productsNp number of atoms of parentk present-day atomic ratio of U238 to U235V yearR atomic ratio

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SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

TABLES FOR THE CALCULATION OF LEAD ISOTOPE AGES

By L. R. STIEFF, T. W. STERN, SEIKI OSHIRO, and F. E. SENFTLE

ABSTRACT

Tables are presented for calculating geologic age by using theatomic ratios of Pb2°«/U238 , Pb2°YU235, Pb207/Pb206, and Pb2"8/Th232 .

Tables of values of Nd/Np and t are given for the age equation

where A is the decay constant,t is age, in millions of years,Nd is the number of atoms of daughter products,

and Np is the number of atoms of parent.Values for Ntm/Nm and t are also given in tabular form for

the age equation

A/2 1)

where N^m and A/2oe are the number of atoms of radiogenic Pb207 and Pb206, respectively, and where k, the present-day atomic ratio of U238 to U235, is taken as 137.7. The half lives (T) of U238, U235, and Th232 used in the calculations are: r238 =4.51X 109 years, 71235=7.13X108 years, Tm=lA2X 1010 years.

The tables cover selected values of t from 1 to 6,000 million years (6X 109 years) at intervals of t ranging from 1 to 15 million years. Only the calculated errors in t resulting from experi­ mental uncertainties in the determinations of the decay con­ stants and relative abundance of U238 and U235 have been in­ cluded. An example is given for a hypothetical geologic age calculation by use of these tables.

INTRODUCTION

Although lead isotope age calculations are in general not difficult to make, both graphs and nomographs are available in the literature to simplify these computa­ tions. Holmes (1931, p. 208) published in "The Age of the Earth" a graphical solution of the age equation involving total lead, uranium, and thorium. Eight years later Wickman (1939, p. 6) published several nomographs that gave ages in millions of years equiva­ lent to the weight ratios of Pb206/U238, Pb^/Pb206 , and Pb 208/Th232. More recently, Kulp and others (1954, p. 345) have prepared nomographs of the three age ratios mentioned above as well as the ratios of Pb207/U235 in terms of numbers of atoms rather than in weight percent.

During the course of geochronological studies mr-de by the U. S. Geological Survey it was found desirable to have age equivalents for the various lead isotope ratios at smaller intervals and over a greater range of time than could be obtained from the references men­ tioned above. Initially, these tables were calculated for the atomic ratios of Pb206/U238, Pb 207/U235, Pb^/Pb206 ,

and Pb 208/Th232 at intervals of t of 1 million years from 1 million years to 6,000 million years. The tables in this paper are an abridgment of the original tables. The calculations were carried to 6,000 million years, an age greater than the probable age of the earth, so tH.t speculative calculations could be made. They are being published because it has been found that for certain types of analysis of isotopic age data these tables are more satisfactory than the published nomo­ graphs. For example, the tables offer greater accuracy and ease of manipulation than the nomographs in making repeated solutions of the age equations. Siich repeated calculations are particularly useful in evaluat­ ing different geologic processes which have produced discordant ages.

The general form of the age equations used to com­ pute the tables was developed by Kovarik (1931, p. 73), Keevil (1939, p. 195), and others. Solutions were obtained for equations of the form

The equation

N_d N,

'207

=expX£

& (expX238<

was solved by iteration. It is important to note that the ratios otNJN, and Nm/Nm in the present tables are given as ratios of number of atoms of daughter (Nd) to number of atoms of parent (Nf), and number of atoms of Pb207 (Nwi) to Pb206 (Moe) and not in terms of weight percent.

The authors wish to express their appreciation to F. W. Reilly and D. B. Rock of the Computer Branch for their aid in the operation of the computer, and also

1

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SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

to Raynor L. Duncomb, Julena S. Duncomb and G. M. Clemence, of the U. S. Naval Observatory, for their cooperation and help in preparing the tables for printing. This work is part of a program being con­ ducted by the U. S. Geological Survey on behalf of the Division of Research of the U. S. Atomic Energy Commission.

The half lives, decay constants, and ratio of U238/U235 used in the calculations are shown in table 1, along with those used by Wickman and by-Kulp and others. The values used in this paper were chosen for the following reasons. Fleming and others (1952, p. 642) discuss in some detail the earlier work on the determination of the half life of U235 . The weighted average of all

previous measurements is numerically tl ?- same as their value with a slightly larger probable error. The half- life data of Fleming and others was therefore chosen for these calculations. These authors have also dis­ cussed the past determinations of the I alf life of U238 . From their "best values" a half life of (4.51 ± 0.007) X 109 years has been calculated. More recently Kovarik and Adams (1955, p. 46) have redetermined three of their original specimens. Their newest value, (4.507± 0.009) X109 years, lies within the limits of error of the "best value" calculation of Fleming and others. In view of the small differences in half lives, as well as the differences in probable error, a value of (4.51 ± 0.01) X 109 years was therefore chosen.

TABLE 1. Physical constants used in calculation of tables

Nuclide

U238 .

U235 _ __ _ - .

Xh232

Atomic ratio IT238/!!235 _____________ _

This paper

i T= (4.51 ± 0.01) X109yX=1.5369 X10-1°y-1

i T=(7.13±0.16)X108yX = 9.72|,X10-1V1

2 T=(1.42±0.07)Xl010yX=4.88, 3 X10-»y-1

3 137.7±0.32

Kulp and others, 1954

T= (4.49 ± 0.0 l)X109yX=1.541X10-10y-1 T=(7.13±0.16)X108yX = 9.722XlO-10y- 1 T=(1.39±0.02)X1010yX= 4.987 XW-ny~ l

137.7 ±0.5

Vickman, 1939

!T=4.56X109yX=1.52X10-i°y-1 T=7.14X108yX=9.72X10-10zr1 T=1.39X10«>yX=4.99X10-"y-1

139.0±1.0

1 Fleming and others, 1952, p. 642.2 Senftle, Parley, and Lazar, 1956, p. 1629.3 Senftle, Stleff, Cuttitta, and Kuroda, 1957, p. 189.

Kovarik and Adams (1938, p. 413) have also deter­ mined the half life of Th232 as (1.39±.03)X1010 years. In their very thorough and excellent paper they deter­ mined in addition the branching ratio of Bi212 . Recently this branching ratio and the half life of thorium have been redetermined by Senftle, Farley, and Lazar (1956). Using a pulse-counting technique they obtained a branching ratio 7.4 percent higher than that obtained by Kovarik and Adams. Although the half life as determined by Kovarik and Adams does not directly depend on the branching ratio of Bi212 , the half life was determined from the basic alpha-count data. In spite of the careful alpha-counting techniques used by Kovarik and Adams, the differences in the branching ratio of Bi212 raise some questions on the earlier Th232 half-life determinations. Also, their calculations de­ pended on the existence of radioactive equilibrium between Th232 and Th228 based on the age of the thorite and the assumption that the daughter products were undisturbed by processes of alteration and weathering. Senftle, Farley, and Lazar, however, have shown that even for a specimen of fresh thorite chosen because it showed no signs of alteration, the Ra224 was 9.5 percent less than the equilibrium amounts; this implies a loss of its parents Th228 and Ra228 . The tendency of radio­ genic daughter products to migrate has been pointed

out in detail by Rosholt (1958). Hence, the value of the half life (1.42±0.07)X1010 years as determined by Senftle and others was used, even though the quoted percent of error is somewhat larger than that of Kovarik and Adams.

The determination of the atomic ratio N238/N235 has been discussed by Fleming and others (1952, p. 642). They observe that a mean value of 137.7 "falls within the limits of error of all values reported." Kulp and others (1954, p. 345) used a value of 137.7±0.5. More recently Senftle, Stieff, Cuttitta, and Kuroda (1957, p. 190) have shown an average value of 137.7 ± 0.32 for 13 uranium specimens. Thi? value with its somewhat smaller probable error has been used for these calculations.

In general, the ratios in the tables r,re given to four significant places, a value somewhat better than can be justified by present physical measurements and analytical methods. The remaining two numbers in smaller type have been included because of their usefulness in certain theoretical calculations. Corre­ sponding to each ratio a value of t plus or minus the error may be read from the tables or may be directly interpolated as a first approximation if the exact value of the ratio desired is not found. Tl e limits of error for t shown in the tables have been calculated by using only the limits of experimental error reported for

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TABLES FOR THE CALCULATION OF LEAD ISOTOPE AGES

the determinations of the decay constants and the are treated more fully in the section "Methods of abundance ratios, and the error term has been rounded computation." to the nearest 0.1 million years. The error calculations

TABLE 2. Errors in t produced by uncertainties in the physical constants used in calculation

Age method

pb206/U238

pb207/U235 ____________________________________

Pb207/Pb206 ___ ___-_-_-_--____-_-_. _ _ _

Pb208/Th232__ ____________________________________

Errors In calculation of various ages, both in millions of years

100

±0. 22±2. 24

±57. 18 ±4. 93

500

±1. 11

±11. 22 ±63.95 ±24. 65

1,600

±3. 33 ±33. 66 ± 82. 21 ±73. 94

2,500

±5.54 ±56. 10

± 102. 38 ± 123. 24

4,500

±9. 98 ± 100. 98 ± 146. 50 ± 221. 83

6,000

± 13. 30 ± 134. 69 ± 181. 65 ± 295. 77

Table 2 lists for several different t's the limits of error in the age calculations resulting from the uncertainties in the physical constants used. This table shows that the limits of error in calculated age for the Pb206/!!238 method are less than the limits of error for the other three methods. The selection of intervals of t (table 3) was determined in part by the limits of error for the

TABLE 3. Range and interval of t

Range (years)

!X10«to 500 X106 500X106 to 1,500X10* 1,500X10* to 2,500X10* 2,500X10* to 4,500X10* 4,509X10* to 6,000X10*

Interval (years)

1X10* 2X10« 5X10*

10X10* 15X10*

might be obtained for the same value of t. Admittedly, the intervals chosen for the abridged tables are smaller that the uncertainties in the calculated ages introduced by the most precise analytical techniques currently available. However, improvements in the quantitative determination of lead, uranium, thorium, and hotopic abundance may ultimately permit the measurersent of small differences in age (1 to 2 million years) of radio­ active minerals from rocks of Cambrian age or younger.

METHODS OF COMPUTATION

THE Nd/Np RELATION

For the purpose of programing this work for the digital computer, the general form of the age ec uation was used,

** &_ T>___\ j 1"Tr"

J.\1i(1)

method. In spite of the larger errors inherent in the other methods, the same interval of t has been used for all four tables in order that equivalent ratios

where i=l, 2, 3 and .7=1, 2, 3.

The values of the decay constants with their limits, X, , used for these calculations are shown in tab11 ^ 4.

TABLE 4. Decay constants \i.(y~')

X

U238Ai 1 = i.5369 xiO-10 U28«X2, = 9.7216 X10-10 Th232X3. = 4.8813 X10-"

X plus error

Xi2 =1.5335 X10-10 H = 9.5082 X10-10 *32 = 4.6520 X 10-"

X minus error

*i3 =1.54o3 X10-»° X23 = 9.9447X10-'°*33 =5. 1344X10-" ^

In computing expX^f 1 the exponential series was expanded

to the uncertainties in the decay constants was simpli­ fied in the following graphical treatment shown in figure 1. By virtue of the geometry in figure 1,

and the recursion -. --. -= . was used to evaluate (n l)\n n\

the series. No round off was used in the evaluation and the maximum error in expX^Z can be shown to be less than 5X10"5 .

The problem of calculating the errors in the ages due

where t2 is the age for a plus error in X and £3 is the age for a minus error in X. Therefore,

and(3b)

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SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

t

FIOTJRE 1. Atomic ratio Nd/Np plotted against the age, t, showing the plus and minus tolerance curves.

Simplifying and taking logarithms,

and

(4a)

(4b)

Also it is evident from figure 1 that MN=ti t3 and NO=t2 ti. Thus, by the substitution the error in the age, MN and NO, can be simply evaluated in a con­ venient form,

and

N0=t ll?-

(5a)

(5b)

If new, more nearly accurate, values of the decay constants become available, it is a simple matter to obtain the corrected age from the tables. For example, suppose the half life of the Th232 is changed from 1.42± 0.07X1010 years to 1.45±0.02X1010 years. Calcu­ lated in this way using T instead of X, the new value of the age, </ say, will be

. , 1.45 t.1.42

Similarly, t2 ' and t3 ' will be

1.47

and

1.42

1.43 t '' 1.42

Then, if one assumes an experimental ratio of A^os/A^a of (O.OSOOaa), the corresponding value of ti (A^os/A^ table) is 1,OOOX106 years. The new half-life value would yield </, tj', and t$ ages of 1,021 X106 years, 1,035X106 years, and 1,007X106 years, respec­ tively. Thus, the tables can still be used even if new values of the half lives are redetermined at a later date.

RELATION

(6)

THE

The general equation,

Nm_v_ expV- 1

'206 *l( ji 1)

was used for computing the Pb207/Pb206 table. The value, ki, used for the U238/!!238 atomic ratio was 137.7 ±0.32 where fc2 and fe3 designate the aburdance ratios with the plus and minus tolerances, respectively.

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TABLES FOR THE CALCULATION OF LEAD ISOTOPE AGES

As in the Nd/Np relation previously described, the calculation of limits of error in the age due to uncertain­ ties in the decay constants has been simplified for programing on the digital computer. By use of a similar graphical argument as shown in figure 2, it can be seen that

i 1 _ expX22 £ 2

and

R=

1) k2 (expXl2 « 2 1)

1 _ expX23 £ 3 1:-!) k3 (expXl3 * 3 -l)

(7a)

(7b)

However, unlike the previous solution, the equations (7a, b) have no direct solution for t2 and t3 and an iterative-approximation method had to be used. The left-hand sides of the equations can be evaluated. The right-hand sides are quotients of infinite series in t2 and t3 . An initial guess was made for t2 or £3, as the case may be, and a test for equality was made. Succes­ sive approximations were made to the t values until equality was obtained.

For the particular case where tl = t2 =t3 Q, the ratio R is indeterminate. However, by using L'Hospital's ule an approximate but quite accurate value of R can

be obtained. Hence, the limits of the ratios as- t\, t2) and <3->0, are #:=0.045936 , #2 =0.0449, ard R3 =0.0470. Thus, radiogenic lead being formed at the present time should and does have a NWI/NSM ratio between 0.045 and 0.047, a value very close to the experimentally observed value.

From the age tables it can be seen that below an age of 56X106 years, the Pb^/Pb206 method has errors that are larger than the calculated value of t. As has been mentioned, this error is due only to the uncertain­ ties in the physical constants used in the calculations. It is shown in figure 2 for an age t, (which is lesn than 56X106 years) that the horizontal line (a-6) between the ages representing the plus and minus tolerances does not intersect the upper curve on the positive side of the coordinates because of the flatness of the curves in this region. Also, this "flatness" and the round-off error cause oscillation of approximately 0.1 to 1.0 million years in the quoted error in t for ages lesr? than 400 million years, and small irregularities in tl ^ 5th and 6th places of the A^/A^oe ratio for the range from 0 to 50 million years.

SAMPLE AGE CALCULATION

A hypothetical uraninite gave the following chemical data: U=43.646 percent, Pb=7.532 percent, Th=5.20!

N207N,206

/?, = 0.0470

/?, = 0.0459

/?2 = 0.0449

485342 O 5£FIGURE 2. Atomic ratio Nsm/Nim plotted against the age, t, showing the plus and minus tolerance curves.

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6 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

percent. For an exact age solution in terms of numbers of atoms it is not necessary to convert these data from the chemical to physical scale of atomic weights by multiplying these values by the conversion factor 1.0002783 given by Nier (1950). This conversion factor cancels out in the lead-uranium ratio age calculations.

However, for an exact age solution, it is necessary to use the calculated physical atomic weight of the lead based on the isotopic composition of the sample being dated rather than the physical atomic weight of average common lead, 207.282. The physical atomic weight of this hypothetical radiogenic lead is obtained by multi­ plying the four lead atom percent abundances by the respective physical atomic weights for the individual lead isotopes. Using the isotopic atomic masses given by Sullivan (1957), 204.0368, 206.039, 207.041, and 208.041, the calculated atomic weight of the radiogenic lead in the uraninite is 206.32. The weight percent of lead corrected for this small factor is :

Failure to correct for differences in atomic weight will result in errors of approximately 0.2 to 0.5 percent in the calculated lead-uranium and lead-thorium ages depending on the atomic weight of the lead in the radioactive mineral and the physical constants used in the calculation.

Isotopic analyses, in atom percent, of lead in uraninite and asso­ ciated hypothetical galena

Pb204

Pb208pK207

pVj208

Lead In

Uranlnlte

0. 1957 81. 178

8. 642 9.984

Associated hypothetical

galena

1.43, 23. 30, 23. 277 51. 98!

The presence of lead originally deposited (common lead) with the uraninite and not produced by the radio­ active decay of the uranium or thorium in the mineral is indicated by 0.1957 percent Pb204 in the isotopic analysis of the lead extracted from the uraninite. Pb204 is the only isotope of lead not known to be pro­ duced by radioactive decay. The isotopic analysis of the hypothetical galena associated with the uraninite is assumed to approximate closely the isotopic com­ position of the nonradiogenic lead originally deposited with the uraninite. As this galena also contains Pb206 ,

Pb207, and Pb208 , it is necessary to correct the uraninite lead before the age calculations can be made.

CORRECTION FOB ORIGINAL COMMON LEAD

The correction for the original common lead may be made in the following way:

1. Using Pb204 as the "index" of the amount of original lead present, a factor proportional to the amount of Pb204 present in the uraninite (0.1957) com­ pared to the Pb204 in the galena (1.438) is obtained.

0.1957 1.43B

=0.13628

2. This factor, when multiplied by the percent abundances of the lead isotopes in the associated galena, will give the proportional amounts of Pb204 , Pb206 , Pb207 , and Pb208 originally present in the uraninite.

Pb204 =1.436 X0.13628 =0.1957

Pb206 =23.306 X0.13628 =3.176

Pb207=23.277 X0.13628 =3.172

Pb208 =51.981 X0.13628 =7.084

3. The isotopic analysis of the lead, in atom percent, from the uraninite is then corrected for the original lead present.

Isotopic analysis of uran-

Isotopic analysis of origi­ nal lead present __ ___

Radiogenic lead pro­ duced by U+Th _ ...

Pbiw

0. 1957

-. 1957

0.000

Pb«»

81. 178

-3. 17,

7&002

Fb«"

F. 642

-?. 172

f . 470

Pb*»

9. 984

-7.084

2. 90o

AQB METHOD

The Pb206/U238 age is obtained by first multiplying the weight percent (chemical scale) of totrl lead by the corrected percent of radiogenic Pb206 produced by the uranium and dividing by the weight perc3nt (chemical scale) of total uranium multiplied by the atom percent abundance of U238, that is 7.567 X78.00; divided by 43.6 46 X99.27s. It is then necessary to convert this weight ratio into an atomic ratio by dividing the physical atomic weight of the uranium, 2?8.103, by the physical atomic weight of the lead, 206.32; that is,

238.103206.32

= 1.154o-

As Avagadro's number would appear in both the denominator and numerator, it can be canceled out

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TABLES FOR THE CALCULATION OF LEAD ISOTOPE AGES

without altering the numerical value of the ratio Nd/Np . The age calculation thus becomes

7.567X78.002 \,-i -leA _ rk I K7Q=43646><99>273 X1.154o-0.15720.

From the tables read 950 ±2.1 million years.

Pb2o7/xj2sj AGE METHOD

Similarly, the Pb207/!!236 age is obtained by multi­ plying the chemical weight percent of total lead by the corrected atom percent abundance of radiogenic Pb207 and dividing by the chemical weight percent of total uranium multiplied by the atom percent abundance of U235 . The conversion factor of weight to atom percent, 1.1 540, is used to change the lead-uranium ratio to an atomic ratio. The Pb207/!!235 age thus becomes

The Pb^/Th232 age thus becomes

From the tables read 950 ±2 1. 3 million years.

Pb2°VPb2M AGE METHOD

The age calculated from the Pb^/Pb206 ratio may be obtained directly from the isotopic composition of the remaining radiogenic Pb206 and Pb207 . The Pb207/Pb206 age thus becomes

NmlNtot -,

From the tables read 950 ±71.9 million years.

Pb«»/Th232 AGE METHOD

The Pb208/Th232 age is obtained by multiplying the total chemical weight percent of lead by the atom per­ cent abundance of remaining radiogenic Pb208 and divid­ ing by the total chemical weight percent of thorium times 100. This ratio is converted to an atomic ratio by using the following factor:

232.111 206.32 ~ L1250°'

From the tables read 950 ±46. 8 million years.Physical isotopic masses were calculated from data

given by Huizenga (1955) and by Sullivan (1957).

LITERATURE CITED

Fleming, E. H., Jr., Ghiorso, A., and Cunningham, B. B., 1952,The specific alpha-activities and half -lives of U284 , U23 ", andU236 : Phys. Rev., v. 88, p. 642-652.

Holmes, Arthur, 1931, Radioactivity and geological time, pt. 4of The age of the earth: Natl. Research Council Bull. 80,p. 124-459.

Huizenga, J. R., 1955, Isotopic masses A>201: Physica, v. 21,p. 410-424.

Keevil, N. B., 1939, The calculation of geological age: Am. Jour.Sci., v. 237, p. 195-214.

Kovarik, A. F., 1931, Calculating the age of minerals from radio­activity data and principles, pt. 3 of The age of the earth:Natl. Research Council Bull. 80, p. 73-123.

Kovarik, A. F. and Adams, N. I., Jr., 1938, The disintegrationconstant of thorium and the branching ratio of thorium C:Phys. Rev., v. 54, p. 413-421.

1955, Redetermination of the disintegration constant ofU238 : Phys. Rev., v. 98, p. 46.

Kulp, J. L., Bate, G. L., and Broecker, W. S., 1954, Presentstatus of the lead method of age determination: Am. Jour.Sci., v. 252, p. 345 365.

Nier, A. O., 1950, A redetermination of the relative abundancesof the isotopes of carbon, nitrogen, oxygen, argon, andpotassium: Phys. Rev., v. 77, p. 789.

Rosholt, J. N., 1958, Radioactive disequilibrium studies as anaid in understanding the natural migration of uranium andits decay products: United Nations Internat. Conf. Peace­ful Uses of Atomic Energy, 2d, Geneva, 1958, Proc. v. 2,Survey of raw material resources, p. 230-236.

Senftle, F. E., Farley, T. A., and Lazar, N., 1956, Half-life ofTh282 and the branching ratio of Bi2U : Phys. Rev., v. 104,p. 1629.

Senftle, F. E., Stieff, L. R., Cuttitta, Frank, and Kuroda, P. K., 1957, Comparison of the isotopic abundance of U236 and U238

and the radium activity ratios in Colorado Plateau uraniumores: Geochim. et Cosmochim. Acta, v. 11, p. 189-193.

Sullivan, W. H., 1957, Trilinear chart of nuclides: U. S. Govern­ment Printing Office, Washington 25, D. C.

Wickman, F. E., 1939, Some graphs on the calculation o* geo­logical age: Sveriges Geol. Undersokning Arsbok, v. 33,no. 7, p. 1-8.

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TABLES FOR THE CALCULATION OF LEAD ISOTOPE AGES[Numbers above tables are the ages, in millions of years, that are given on each page]

Page 17: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic
Page 18: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

TABLES FOR THE CALCULATION OF LEAD ISOTOPE AGES

1-50

11

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0.0001530.0003070.0004610.0006i40.0007680.0009220,0010750.0012290.0013830.0015370.0016910.0018450.0019980.0021530% 0023o70.0024620.0026150.0027690.0029240.0030770.0032320.0033860.0035400.0036940.0038490.00400 20.0041570.0043120.0044660,0046200.0047750.0049300.0050830,0052380.0053930.0055470.0057020.0058570.0060io0.0061650.0063200.0064750.0066290.0067840.0069390.0070930.0072490.0074o40.0075580.007713

AgeNumber

of years

123456789

101112131415161718192021222324252627282930

3132333435363738394041424344454647484950

Error+

0.00,00,00.00.00,00.00,00.00.00,00.00,00,00,00.00.00.00,00.00,0o.o0.10.10.10,10.10.10.10.1

0.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10,10.1

N 207/N 235

Ratio

0.0009720.0019450.0029200.0038950.0048710.0058490.0068280.0078070.0087870.0097680.0107500.0117330.0127170.0137020.0146880.0156740.0166&20.0176510.0186420.0196330.0206240.0216160.0226090.0236050.0246oo0.0255970.0265950.0275930.0285920.0295930.0305940.0315970.0326oo0.0336050.0346o90.0356i60.0366220.0376320.0386410.0396510.0406620.0416740.0426870.0437020.0447160.0457320.0467490.0477670.0487870.0498o7

AgeNumber

of years

123456789

101112131415161718192021222324252627282930

3132333435363738394041424344454647484950

Error ±

0.00.00.10.10.10.10.20.20.20.20.20.30.30.30.30.40.40.40.40,40.50.50.50,50.60.60.60.60.70.70.70.70.70.80.8

0.80,80.90.90.90.90.91.01.01,01,01.11.1XIXI

"2077*206

Ratio

0.0459550.0459740.0459930.0460i20,0460300.0460490.0460680.0460870.0461060.046124

0.0461430.0461620.0461810.0462oo0.0462i90.0462370.0462560.0462750.0462940.0463130.0463370.0463610.0463800.0463990.0464i70.0464360.0464550.0464740.0464930.0465i30.0465320.0465510.0465700.0465890.0466070.0466260.0466450.0466640.0466820.0467oi0.0467200.0467390.0467580.0467770.0467960.0468i50.0468340.0468530.0468720.046891

AgeNumber

of years

123456789

101112131415161718192021222324252627282930

3132333435363738394041424344454647484950

Error +

55855.255.255.255.155.155.155.155.155.156.656,757,756.756.655.656.556.655.856.9

56.356.356.456.656,156.956.456.056.356.556.256.056.656.456.156.456,256.156.856.556.456.356,656.556.356.656.256,156,556.5

N2 08/^2 3 2

Ratio

0.0000480.0000970.0001460.0001950.0002440.0002920.0003410.000390010004390.0004880,0005360,0005850.0006340.0006830.0007320.0007810.0008290,0008780.0009270.0009760.0010250.0010730.0011220.0011710,0012200.0012690.0013170.0013660.0014160.0014650.0015140.0015630.00l6ii0.0016600.0017090.0017580.001807O.OOlSss0.0019040.0019530.0020o30.00205 20.0021oo0.0021490.0021980.0022470.0022960.0023450.0023930.002442

AgeNumber

of years

123456789

101112131415161718192021222324252627282930

3132333435363738394041424344454647484950

Error +

o.o0,10.10.20,2

0.30.30.40.40.50.50.60.60.70.70.80.80.90.9xoxoXIXIX2X2X31,3X4X4X5X5X6X6X7X7X8X8X9X92.02.02.12,12.22.22.32,32.42,42.5

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12 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

51-100

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0.0078680.0080220.0081780.0083330.0084880.0086430.0087980.0089530.0091o80.0092630.0094180.0095730,0097280.0098840,010038

0.0101940.0103500.0105050.0106600.0108150.0109710.0111260.0112810.0114370.011592

0.0117480.0119040.0120580.0l22i40.0123700.0125260.0126810.0128370.0129930.013148

0.0133040.0134600.0136150.0137710.0139270.0140820.0142380.0143950.0145510.0147060.0148620,0l50i90.0151740.0153300.015487

AgeNumber

of years

51525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899

100

Error ±

0.10.10.10.10.10.10.10.10.10.1

0.10.10.10.10.10.10.10.20,20,20.20.20.20.20.20.20.20.20.20.20.20,20.20.20,20.20.20.20.20.20.20.20.20.20.20.20.20.20.20.2

^207/^235

Ratio

0.0508290,0518500.0528730.0538970.0549220.0559470.0569760.0580o30.0590320.0600630.0610930.0621250.0631590.0641930.0652280.0662640.0673oi0.0683390.0693780.0704180.0714590.0725oi0.0735450.0745890.0756340.0766810.0777270.0787750.0798250.0808750.0819260.0829790.0840320.0850860.0861420.0871980.0882550.0893i50.0903740.0914340.0924960.0935580.0946210.0956870.0967530.0978190.0988870.0999560.1010250,102096

AgeNumber

of years

51525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899

100

Error+

1112121212

13131313131.41414141515151515161616161717171.71818181818191919192,02.02.02.02.02.12.12.12.12.22.22.22.22.2

N 207/N206

Ratio

0.0469io0,0469290,0469480.0469670,0469860.0470050.0470240.0470430.0470620.0470810.0471oo0,0471i90,0471380.0471570.0471760,0471960.0472160.0472430.0472640,0472840.0473oi0.0473220.0473440.0473610.0473830.0474oi0.0474180.0474430,0474620,0474790.0474980.0475200.0475380.0475570.0475790.0475980.0476160.0476400,0476580,0476770.0477oo0.0477190.0477350,0477550.0477780.0477980.0478150.0478380.0478570,047874

AgeNumber

of years

51525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899

100

Error

±

56.656,756.456.456.556.456.556.556.556.656.656,756,856.756,956.856.656.756.856.956.756.856.956.956.956.956.857.057.056.956.957.057.056.957.157.056.957,157.057,157.257.257.157.157.357.357.257.357.357.2

^208/^232

Ratio

0.0024920.0025410.0025900.0026380.0026870.0027360.0027850.0028350.0028830,0029320,0029ai0.0030300.0030790.0031280.0031770.0032260.0032750,0033240.0033730.0034210.0034710.0035200.0035690.0036180.0036670.0037150.0037650.0038i40.0038630.0039i20.0039600.0040io0.0040590.0041oa0.0041570.0042050.0042550.0043o40.0043530.0044o20.0044510, 0045oo0,0045490.0045980.0046470.0046960.0047450.0047940.0048430.004892

AgeNurrber

of years

51525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899

100

Error +

2.52.62.62.72.72,82.82.92.93.03.03.13.13.23,23.33,33,43.43.53.53,53.63.63,73.73.83.83.93.94.04.04.14,14.24.24,34,34.44,44.54.54,64.64.74.74.84.84.94,9

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TABLES FOR THE CALCULATION OF LEAD ISOTOPE AGES

101-150

13

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0,0156420,0157980,0159550.0161io0.0162670.0164230,0165800.0167350,0168920.0170480.0172o40.0173610.0175i70.0176730.0178300.0179860.0181420.0182990.0184570.0186i40.0187&90.0189260.0190830.0192390.0193960.0195530.0197090.0198&60.0200230.0201790.0203360.0204930.0206500.0208o70.0209640.0211210.0212770.0214340,0215920.0217480.0219o50.0220630.0222i90.0223760.0225340.0226910.0228480.0230ns0.0231630.023320

AgeNumber

of years

101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150

Error +

0.20.20.20,20.20,20.20.20,20.20.20,20.30.30.30,30.30.30,30.30.30,30,30.30.30.30.30,30.30.30,30,30,30.30.30.30.30,30,30.30,30.30.30.30,30,30.30.30.30.3

"207/^235

Ratio

0.1031680.1042420.1053160.1063910.1074&60.1085430,1096220.1107010,1117820.1128620.1139450.1150280.1161i30.1171990.1182850.1193720.1204&10.1215510.1226430.1237340.1248270.1259220.1270i601281ii0.1292io0.1303090.1314070.1325080.1336090.1347ii0.1358150.1369210.1380260.1391330,1402410.1413sn0.1424&00.1435720.1446840,1457970.1469ii0.1480270.1491430.1502&10.1513800.1524990.1536210.1547420.1558&50.156989

AgeNumber

of years

101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150

Error +

2.32,32,32.32.42.42.42.42.42.52.52.52.52.62.62,62.62.62.72,72.72.72.82.82.82.82.82.92.92.92.93.03.03.03.03.13.13.13.13.13.23.23.23.23.33.33,33.33.33.4

^207/^206

Ratio

0.0478980.0479i80.0479360.0479590.0479760.0479970, 0480is0.0480380.0480570,0480770.0480980.0481160.0481370.0481590.0481770.0481980,0482200.0482380.0482550.0482740.0482980.0483170,0483360.0483580.0483780.0483970.0484i90.0484390.0484580.0484800.0485oo0,0485210.0485400.0485&00.0485810.0486oi0,0486230.0486440.0486&20.0486850.0487050,0487230.0487460.0487&70.0487860.0488060.0488270.0488480.0488&70.048888

AgeNumber

of years

101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150

Error +

57.457.557.357.557.357.457.357.557.457,457.557.457.557.757.657.657.757.657.457.457.657.557.557.657.657.657.757.757.657.757.857.857.757.857.857.857.957,957.858.057,957.858.058,158.058.058.058.158.158.0

N208/

Ratio

0,0049420,0049900.0050,390,0050880.0051380.0051870.0052360.0052840,0053340,0053830,0054320,0054810.0055300.0055790.0056280.0056780.0057270.0057750,0058240.0058740.0059230.0059720.00602200060700.0061i90,0061680.0062i80.0062&70,0063i50.0063650.0064i40.0064&30.0065i30.0065610.0066io0.0066&00.0067090.0067580.0068080.0068560,0069o50.0069550.0070040.0070530.0071020.0071510.0072oo0.0072500.0072990.007348

//V232

AgeNumber

of years

101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150

Error +

5.05,05.15,15,25.25.35,35.45,45.5$55,65.65.75.75.85.85.95,96,06.06.16,16.26.26.36,36.46.46.56.56.66.66,76.76.86.Q6,96.97.07.07.07.17.17,27.27.37.37,4

485342 O 59-

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14 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

151-200

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0.0234780.0236350,0237920.0239500, 0241070,0242640.0244220.0245790.0247360.024894

0.0250520.0252090.0253660,0255240.0256820.0258390.0259970.0261550.0263i20.026470

0.0266290.0267860.0269440.0271020.0272600.0274i70.0275760.0277340.0278910.028049

0.0282070.0283650.0285230.0286810.028839

0.0289970.0291550.0293150.0294720.029631

0.0297890.0299470.0301Q50.0302640.0304220.0305800.0307390.0308960.0310550.0312i4

AgeNumber

of years

151152153154155

156157158159160

161162163164165

166167168169170

171172173174175176177178179180

181182183184185

186187188189190

191192193194195

196197198199200

Error ±

0.30.30.30.30.3

0.30.30.40.40.4

0,40.40.40.40.40.40.40.40.40.4

0.40.40.40.40.40.40.40.40.40.4

0.40.40.40.40.4

0.40.40,40.40.4

0.40.40.40.40.40.40.40.40.40.4

*207/"235

Ratio

0,1581160.1592410.1603690,1614970162627

0.1637580.1648900.1660230.1671,570.1682930.1694290.1705660.1717060.1728440.173985

0.1751270.1762&90.1774i40.1785600.1797070.1808530.1820o20.1831510.1843020.1854530.1866070.1877620.1889i70.1900730.191231

0.1923870.1935490.1947io0.1958710.197034

0.1981990.1993640.2005310.2016980.202867

0.2040360.2052070.2063790.2075540.2087290.2099040.2110810.2122590.2134380.2146i7

AeeNumber

of years

151152153154155

156157158159160

161162163164165

166167168169170

171172173174175176177178179180

181182183184185

186187188189190

191192193194195196197198199200

Error ±

3.43.43.43.53.5

3.53.53.53.63.6

3.63.63.73.73.7

3.73.73.83.83.8

3.83.93.93.93.93.94.04.04.04.0

4.14.14.14.14.2

4.24.24.24.24.3

4.34,34.34.44.44.44.44.44.54.5

N 207/

Ratio

0.0489080.0489280.0489500.0489690.0489900.0490i20.0490310.0490530.0490750.049095

0.0491i40,0491360.0491580.0491780.0491980.0492200.0492400.0492600.0492820.049303

0.0493210.0493440.0493640.0493840,0494050.0494280.0494470,0494680,0494900.0495H

0.0495310.0495530.0495740.0495950.0496160.0496380.0496590.0496770.0497oo0.049720

0.0497410.0497620.0497840.0498040.0498260.0498480,0498680.0498910.0499i20.049932

'*206

AgeNumber

of years

151152153154155

156157158159160

161162163164165

166167168169170

171172173174175

176177178179180181182183184185186187188189190

191192193194195

196197198199200

Error

±

58.058.058.158,058.1

58.258.158.258.358.2

58.258.358.458.358.3

58.458.358.358.458.5

58.358.458.458.458.458,558.458.458.658.658.5sa658.653,658.658.758.758.658.758.7

58.758.758.858.758.858.858.858,958.958.8

^208/^232

Ratio

0.0073970.0074460.0074950.0075450.007594

0.0076420,0076920.0077410.0077910.007840

0.0078880.0079380.0079870.0080370.008086

0.0081350.0081840.0082330.0082830.0083320.0083810.0084300,0084790.0085290.0085780.0086270.0086760.0087250.0087750.008824

0.0088740.0089230.0089710.0090210,0090700.0091200.-0091690.0092i80.0092670.0093i7

0.0093660.0094i50,0094640,0095i30,0095630.0096i20.0096620.0097ii0.0097600, 009809

AgeNumber

of years

15115?15315415515<>157153159160

16116?163164165166167168169170

1711721731741751761771781791PO

in1P21831P41P5

1M1P71PB1P9190

191192193194195

196197198199200

Error +

7.47.57,57.67,67,77.77.87.87.97.98.08.08.18.1

8.28.28.38.38.4

8.48.58.58.68.6a78.78.88.88.9

8.99.09.09.19.19.29.29.39.39,4

9.49.59.59.69.69.79.79.89.89.9

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TABLES FOR THE CALCULATION OF LEAD ISOTOPE AGES

201-250

15

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0.0313730.0315300,0316900.0318490.0320o70.0321660.0323250.0324820.0326410,0328oo0.0329580.0331i70.0332760.0334350.0335940.0337540.0339i30.0340710.0342300,0343890.0345470.0347o70.0348&60.0350240.0351830.0353430.0355030.0356&10,0358210.0359800.0361390.0362980.0364580.0366i60.0367760.0369350.0370950.0372540.0374i40.0375740.0377320.0378920.03805 20.0382ii0.0383700.0385300.0386900.0388500.0390io0.039169

AgeNumber

of years

201202203204205206207208209210

211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250

Error ±

0.40.40.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50,50.50.50,50.50.50.50.50,50.50.60.6

^207/^235

Ratio

0.2158oo0.2169820.2181&60.2193500.2205360.2217220.2229i30.2241oi0.2252910.2264840.2276760.2288700.2300660.2312&30,2324600.2336&00.2348580.2360600.2372&20.2384&60.2396&90.2408750.2420830.2432910.2445oo0.2457H0.2469220.2481340.2493480.2505640.2517790.2529980.2542i60.2554360.2566580.2578790.2591030.2603280.2615540.2627800.2640o80.2652380.2664&90.2677oi0.2689340.2701680.2714030.2726390.2738780.275116

AeeNumber

of years

201202203204205206207208209210

211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250

Error +

4.54.54.64.64.64,64.64.74.74.74.74,84.84.84.84.84,94.94.94.95.05.05.05.05,05.15.15.15.15.25.25,25.25.35.35.35.35.35.45.45.45,45,55.55.55.55.55,65,65.6

"207/^206

Ratio

0.0499520.0499760.0499950.0500i50.050038O.OSOOss0.0500790.0501030.0501240.0501450.0501670.0501880.0502090.0502300.0502510.0502710.0502920.0503150.0503370,0503580.0503810.0504oi0.0504220.0504450.0504670.0504870.0505080.0505310.0505510.0505730.0505950.0506170.0506370.0506610.0506820.0507040.0507250.0507470.0507680.0507890.0508120.0508330.0508550.0508770.0509oo0,0509210.0509420.0509630.050985O.OSlOos

AgeNumber

of years

201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250

Error +

58.859,058.9sas59,058.958.959,159.159.059,159,159.159.159.159.059.059.259.259.259,359.259,259.359.359.259.359.459,359.359,459,459.459.559.559,559.559,559.559.559,659.559.659.659,759.759,659,659,659.7

N208/

Ratio

0.0098590.0099080.0099580.0100060.010056

0.0101050.0101550,0102040.0102530,0103020.0103520.0104010.0104510.0105oo0.0105490,0105980.0106480,0106970,0107470.0107950,0108450.0108940.0109440.0109930.011043

0.0110910.0111410.0111900.0112400.0112900.0113380.0113880.0114370,0114870.011536

0.0115850.0116340.0116840.0117340.011783

0.0118330.0118810.0119310,0119800.0120300.0120800.0121280.0121780.0122270.012277

^232

AgeNumber

of years

201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250

Error +

9.910.010.010,110.110.210.210,310,310.410.410,510,510.510.610.610.710.710.810.810.910.911,01101111L111.211211.311311.411411.511511611611711711811.811911912.012.012.112112.212.212312.3

Page 23: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

251-300

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

"206/^238

Ratio

0.0393290.0394890.0396480.0398070.0399680.0401290.0402880,0404480.0406080.0407670^0409270,0410870.0412460.0414080.0415&80.0417280.0418870.0420480.0422080.0423&70,0425290.0426890.0428490.0430090.0431700.0433290.0434900.0436500.0438i20.0439710.0441320.0442930.0444520.0446i30.0447750.0449350.0450950.0452560.0454i60.0455770.0457380.0459oo0.0460590.0462200.0463810.0465410.0467020.0468&30.0470240.047185

AgeNumber

of years

251252253254255256257258259260

261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300

Error±

0.60.60.60.60.60,60.60.60.60.60.60.60.60.60.60.60,60.60.60.60.60.60.60.60.60.60.60.60.60.60.60.60.60.60.60.60.60.60.60,60.60.60.60.70.70.70.70.70.70.7

N 207/N235

Ratio

0.2763570.2775990.2788410.2800840.2813300.2825750.2838250.2850720.2863220.2875740.2888250.2900780.2913350,2925900.293847

0,29510602963650.2976250.2988890.300152

0.3014i60.3026810.3039480.3052160.3064860,3077570.3090300.3103020.3115770.3128520.3141280.3154070.3166870.3179680,3192490.3205320.3218i70.3231020.3243900.3256780.3269&70.3282580.3295490.3308440.3321380.3334330.3347290.33602703373270.338627

AgeNumber

of years

251252253254255256257258259260

261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290

291292293294295296297298299300

Error ±

5.65.75.75.75.75.75.85.85.85.85.95.95.95.95.96.06,06.06,06.16.16.16.16.16.26,26.26.26.36.36.36.36.46.46.46.46,4656,56,56.56.66.66.66.66.66.76.76.76.7

"207/N206

Ratio

0.0510290.0510510.0510740,0510960.0511i70.0511370.0511610.0511820.0512040.0512270.0512490.0512710.0512950.0513i40.0513360.0513580.0513820.0514030.0514250.0514490.0514690.0514910.0515i30.0515360.0515570.0515810.0516030.0516250.0516460,0516700.0516910.0517i30,0517370.0517590.0517790.0518o20,0518250.0518470.0518710.0518920.0519i40.0519360.0519600.0519820.052 Oo 40.0520280.05205 o0.0520720.0520950.0521i7

AgeNumber

of years

251252253254255256257258259260

261262263264265

266267268269270

271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300

Error+

59.759,759.859,859.759.759.859.859.859.859.959.960.059.959.959,960.060.060.060,160.060,060.060.160% 060.160,260.260.160.260,160.260.360.360.260.260.360.360.460.3

60.360.360,460.460.4

60.560.560.560.560,5

^208/^232

Ratio

0.0123270.0123750.0124250,0124740.0125240.0125740.0126230.0126720.0127210.0127710.0128210.0128700,0129i90.0129&90.0130i8

0.0130&80.0131170.0131660.0132i60.0132&50.0133150.0133650.0134i40.0134630.0135130.0135620.0136120.0136620.0137io0.0137&00.0138io0.0138590.0139090.0139580.0140070,0140570,0141070.0141560.0142060.0142550,0143040,0143540.0144040.0144530,014502

0.0145520,0146o20.0146510, Ol47oi0.014751

AgeNuml °r

of years

251252253254255256257258259260261262263264265

266267268269270

2712722732742752762772782792802£12£<l2£32£42£52£62872£82 £02<50

2912922S32<542952<562972982co3CO

Error +

12.412.412.512.512.612,612.712,712.812.812.912.913.013.013.1

13.113.213,213.313,313.413.413.513.513.613.613-713,713.813.813.913,914.014.014.0

14.114.114.214.214.314.314.414.414.514.5

14.614,614-714.714.8

Page 24: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

TABLES FOR THE CALCULATION OF LEAD ISOTOPE AGES

301-350

17

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

N 206/N 238

Ratio

0.0473470.0475070.0476680.0478290.047990

0.0481510.0483i30.0484740.0486340.048796

0.0489580.0491i80.0492800.0494410.0496oi

0.0497640.0499250.0500860.0502470.0504o9

0.0505700.0507320.0508940.0510550.0512i6

0.0513780.0515400.0517oi0.0518630.052025

0.0521850.0523480.0525io0.0526720.052833

0.0529950.0531580.0533190.0534810.053643

0.0538040.0539670.0541290.0542900.054452

0.0546i50.0547780.0549390.0551oi0.0552&3

AgeNumber

of years

301302303304305

306307308309310

311312313314315

316317318319320

321322323324325

326327328329330

331332333334335

336337338339340

341342343344345

346347348349350

Error +

0.70.70.70,70.7

0.70.70.70.70,7

0.70.70.70.70.7

0.70.70.70.70.7

0.70.70,70.70.7

0.70.70.70.70.7

0.70.70.70.70.7

0.70.70.70.80.8

0.80.80.80.80.8

0.80.80.80.80.8

"2077*235

Ratio

0.3399300.3412340.3425370.3438430.345151

0.3464590.3477690.3490800.3503930.351705

0.3530220.3543360.3556540.3569730.358293

0.3596i30.3609350.3622590.3635840.3649ii

0.3662380.3675680.3688980.3702280.371561

0.3728960.3742310.3755670.3769050.378244

0.3795840.3809280.3822700.3836150.384959

0.3863060.3876540,3890040.3903560.391708

0.3930&20.3944i60.3957730,3971310.398489

0.3998490.4012ii0.4025740.4039390.405303

AgeNumber

of years

301302303304305

306307308309310

311312313314315

316317318319320

321322323324325

326327328329330

331332333334335

336337338339340

341342343344345

346347348349350

Error +

6.86.86.86.86.86.96.96.96.97,0

7.07.07.07.07.1

7.17,17.17.27,2

7.27.27.27.37.3

7.37.37.47.47.4

7.47.57.57.57.5

7.57.67.67.67.6

7.77.77.77.77.7

7.87.87.87.87.9

N 207/

Ratio

0.0521390.0521620.0521850.0522070.052230

0.0522530.0522740.0522970.0523210.052343

0.0523&50.0523890.0524H0.0524340.052458

0.0524790.0525020.0525250.0525480.052570

0.0525940.0526i60.0526380.0526610.052685

0.0527080.0527300.0527530.0527760.052799

0.0528230.0528450.0528680.0528910.0529i4

0.0529370.0529590.0529830.0530o60.053029

0.0530530.0530750.0530980.0531220.053145

0.0531670.0531900.0532i40.0532380.053261

/N206

AgeNumber

of years

301302303304305

306307308309310

311312313314315

316317318319320

321322323324325

326327328329330

331332333334335

336337338339340

341342343344345

346347348349350

Error +

60.560.560.660.660.6

60.660,660.660.760.7

60.760.760.760,860.8

60.860.860.860.860.8

60.960.960.960.96X0

61.061.061.061.061.0

61.161.161.161,161.1

61.161161261.2612

61.261.261.261.261.3

61.36X261.36X36X3

N208/

Ratio

0.0147990.0148490.0148990.0149490.014998

0.0150470.0150970.0151470.0151960.015246

0.0152950.0153440.0153940,0154440.015494

0.0155430.0155920.0156420.0156920.015741

0.0157910.0158400.0158900.0159400.015989

0.0160390.0160880.0161380.0161870.016237

0.0162870.0163370.0163860.0164350.016485

0.0165350.0165850.0166340.0166830.016733

0.0167830.0168330.0168820.0169310.016981

0.0170310.0170810.0171310.0171800.017229

^232

A^eNumber ~

, Error of +

years

301 14.8302 14.9303 14.9304 15.0305 15.0

306 15.1307 15.1308 15.2309 15.2310 15.3

311 15.3312 15.4313 15.4314 15.5315 15.5

316 15.6317 15.6318 15.7319 15.7320 15.8

321 15.8322 15.9323 15.9324 16,0325 16.0

326 16.1327 16.1328 16.2329 16.2330 16.3

331 16.3332 16.4333 16.4334 16.5335 16.5

336 16.6337 16.6338 16.7339 16.7340 16.8

341 16.8342 16.9343 16.9344 17.0345 17.0

346 17.1347 17.1348 17.2349 17.2350 17.3

Page 25: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

18 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

351-400

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

N 206/N 238

Ratio

0.0554260.0555880.0557500.0559i20.0560750.0562370.0563990.0565610.0567240.0568870.0570490.0572ii0.0573740.0575360.0576990.0578620.0580230.0581870.0583500.0585110.0586740.0588380.0590oi0.0591620.0593250.0594890.0596510.0598140,0599770,0601400.0603030.0604660.0606280.0607920,0609550.0611180,0612810.0614440.0616080.0617700.0619340,0620970.0622600,0624230.0625870.0627500.0629130.0630770.0632410.063403

AgeNumber

of years

351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400

Error±

0.80.80.80.80.80.80.80.80.80.80.80.80.80,80.80.80.80.80.80.80.80.80.80.80.80.80.80,80.80.80.80,80.80,90.90.90.90.90.90.90.90.90.90.90.90.90.90.90.90.9

"207

Ratio

0.4066710.4080400.4094080.4107800.4121510.4135240.4149oo0.4162760.4176550.4190320.4204i30.4217940.4231780.4245620.4259470.4273330.4287220.4301io0.4315010.4328950.4342890.4356830.4370800.4384770.4398760.4412770.4426800.4440820,4454860,4468920.4483010.4497080.4511i90.4525300.4539430.4553560.4567710.4581900.4596090.4610280.4624490.4638700.4652940.4667180.4681470.4695750.4710040.4724350.4738660.4753oo

/"235

AeNumber

of years

351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400

e

Error±

7.97.97.97.98.08.08.08.08.18.18.18.18.18.28,28.28.28,38,38.38,38.38.48.48.48,48.58.5as8.58.58.68.68.68.68.78.78.78,78.88.88.88.88.88.98.98.9a99.09.0

N 2Q7/N 206

Ratio

0.0532830.0533070.0533300.0533540.0533760.0534oo0.0534240.0534470.0534700.0534930.0535170.0535410.0535640.0535870.0536io0.0536330.0536580.0536800.0537040.0537290,0537520.0537740.0537980.0538230,0538460.0538690.0538930.0539i70.0539400.0539640.0539870.0540ii0.0540360.0540580.0540820.0541060.0541300.0541540.0541770.0542o20.0542250.0542480.0542730.0542970.0543200.0543440.0543680.0543920.0544150.054440

AgeNumber

of years

351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400

Error +

6X46X46X46X46X46X461,56X56X56X56X66X661.66X66X66X66X76X66X66X76X76X66X76X86X86X86X86X96X86X86X96X96X96X96X962.062.062.062.062,062.062.062.162.162.162.162.262.262.262.2

N208/N2 3 2

Ratio

0,0172790.0173290.0173790,0174280.0174780.0175270.0175770.0176270.0176770.0177260.0177760.0178260.0178750.0179250.0179740.0180240.0180740,0181240.0181740.0182230.0182720.0183220.0183730.0184230,0184730.0185220.0185720.0186220.0186720.0187220.0187700.0188200.0188700,0189200.0189700.0190i90.0190690.0191190.0191690.0192190.0192690.0193180,0193670.0194170.0194670.0195170.0195660.0196160.0196&60,019716

AgeNumber

of years

35135?35335435535635735835936036136?3633643653663673683693703713723733743753763773783793PO3P13P?3P33P4385386387388389390391392393394395396397398399400

Error +

17.317.417.417.517.517.517.617,617.717.717.817.817.917,918.018.018.118.118.218,218,318,318,418.418,518.518.618,618,7181718,8ias18,918.919.019.019,119.119,219,219,319.319,419,419.519,519.619.619,719.7

Page 26: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

TABLES FOR THE CALCULATION OF LEAD ISOTOPE AGES

401-450

19

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0.0635680.0637310.0638940.0640570,064222

0.0643840.0645480.0647i30.0648750.065039

0.0652040.0653&70.0655300.0656940.065859

0.0660210.0661850.0663500.0665i30.066677

0.0668420.0670o50.0671&90.0673340,067498

0.0676&10.0678260.0679900.0681530.068318

0,0684820.0686460.0688ii0.0689750.069138

0.0693040.0694&80.0696320.0697970.0699&1

0.0701250.0702900.0704540.0706i90.070783

0.0709480.0711i30.0712770.0714410.071607

Age

Number of

years

401402403404405

406407408409410

411412413414415

416417418419420

421422423424425

426427428429430

431432433434435

436437438439440

441442443444445

446447448449450

Error +

0.90.90.90.90.9

0.90.90.90.90.9

0.90.90.90,90.9

0.90.90.90.90.9

0.90.90.90.90.9

0.90.90.9101.0

1010101.010

101.01.01.01,0

1.0101.01.01.0

1.0101,01.0XO

^207/^235

Ratio

0,4767370.4781710.4796080.4810490.482489

0.4839300.4853740.4868200.4882650.489712

0.4911600.4926io0.4940&30.4955160.496971

0.4984270.4998850.5013440,5028040.5042&7

0.5057290.5071920.5086530.5101260.511595

0.5130650.5145370,5160o90,5174850.518960

0,5204370.5219i70.5233980,5248780.5263&1

0.5278450.5293330.5308210.5323090.5338oo

0.5352910.53678405382780.5397740.541275

0.5427730.5442730.5457740.5472770.548782

Age

Number of

years

401402403404405

406407408409410

411412413414415

416417418419420

421422423424425

426427428429430

431432433434435

436437438439440

441442443444445

446447448449450

Error+

9.09.09.09.19.1

9.19.19.29.29.2

9.29.29.39.39.3

9.39.49.49.49.4

9.49.59.59.59,5

9.69.69.69.69.6

9.79.79.79.79.8

9.89.89.89.99.9

9.99.99.9

10.010.0

10010.010.110.110.1

W 207/

Ratio

0.0544630.0544870.0545120.0545360,054559

0.0545840.0546080.0546310,0546560.054680

0.0547030.0547280.0547530.0547760.0548oo

0.0548250.0548490.0548730,0548980.054922

0.0549450.0549700.0549940.0550i80.055042

0.0550&80.0550910.0551160.0551410.0551&5

0.0551890.0552i40.0552380.0552&20.055288

0.0553110.0553360.0553610.0553850.0554io

0.0554340.0554590.0554830.0555080.055533

0,0555570.0555810.0556070.0556320.055655

'W 206

Age

Number of

years

401402403404405

406407408409410

411412413414415

416417418419420

421422423424425

426427428429430

431432433434435

436437438439440

441442443444445

446447448449450

Error +

62.262.262.362.362.3

62.362.462.362.462.4

62.362.462.562.462.5

62.562.562.562.662.6

62.562.662.662.662.6

62.762.762.762.762.7

62.762,862.862,862,9

62.862.862.962.962.9

62.962,962.963.063.0

63.063.063.163.163.0

N208/N232

Ratio

0,0197660,0198150.0198&50.0l99i50.0199&5

0, 0200i50.0200650.0201i40.0201&40,0202i4

0,0202640.0203140.0203&30.0204i30.0204&3

0.0205130.0205&30, 0206120.0206&20.0207i2

0.0207&20.0208i20.0208&20.0209110.020961

0.0210ii0.0210&10.0211110.0211600.0212io

0.0212&00,0213io0.0213&00, 0214io0.021459

0,0215o90,0215590.0216090.0216590.021708

0.0217580.0218080.0218580, 0219o80.021957

0.0220070.0220580, 0221080.0221580.0222o8

Ag-

Number of

years

401402403404405

406407408409410

411412413414415

416417418419420

421422423424425

426427428429430

431432433434435

436437438439440

441442443444445

446447448449450

Error +

19.819.819.919.920.0

20.020,120,120,220.2

20L320.320.420.420.5

20,520.620.620,720.7

20,820.820.920.921.0

21.021.021,121.121.2

21.221.321.321.421.4

21.521.521.621.62X7

21.721,82X821.92X9

22.022.022,122.122.2

Page 27: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

20 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

451-500

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0.0717710.0719350.0721oi0.0722660.072430

0.0725950.0727&10.0729260,0730910.073256

0.0734200.0735850.0737510,0739i50,0740800.0742460.0744H0.0745760.0747410.0749060.0750720,0752370.0754030.0755&70.0757320.0758980.0760&30.0762290.0763940.076560

0,0767250,0768900.0770570.0772210.077388

0.0775530.0777180.0778840.0780500.078215

0.0783810.0785470.0787130.0788780.0790440.0792io0,0793760.0795420.0797080.079873

AgeNumber

of years

451452453454455

456457458459460

461462463464465466467468469470

471472473474475

476477478479480

481482483484485

486487488489490

491492493494495496497498499500

Error±

1.01.01.01.01.0

1.01.01.01.01.0

1.01.01.01.01.0

1.01.01.01.01.01.01.01.01.1u1.11.11.1u1.11.11.11.11.11.11.11.1u1.1uu1.11.1u1.11.1u1.11.11.1

^207/^235

Ratio

0.5502890.5517970.5533070.5548i80.5563300.5578430.5593&00.5608750.5623920.5639i3

0.5654330.5669570.5684810.5700070.5715330.5730600.5745920.5761230.5776560.5791910.5807270.5822640.5838030.5853430.586885

0.5884290.5899740.5915200.5930&90,5946i70.5961680.5977220.5992760.6008320.602389

0.6039470.6055070.6070690.6086320.610197

0.6117610.6133300.6148980.6164&90.618043

0.6196i70.6211910.6227670.6243460.625927

AeeNumber

of years

451452453454455

456457458459460

461462463464465

466467468469470

471472473474475

476477478479480

481482483484485

486487488489490

491492493494495496497498499500

Error±

10.110.110.210.210.2

10.210.310.310.310,3

10.310,410.410.410.4

10.510.510.510.510,510.610.610.610.610.710.710.710J10.710.8

10.810.810.810.910.9

10.910.911.011.011.0HO11.011.1HI11.111.111.211.21X2U2

W 207/W206

Ratio

0.0556810.0557060.0557300.0557540.055780

0,0558040.0558280.0558530.0558780.055902

0.0559280.0559530.0559770.0560030.056028

0.0560520.0560770.0561020.0561270.0561520.0561770.0562020.0562260.0562520.056278

0.0563020.0563280.0563520.0563780.056402

0.0564280.0564540.0564780.0565040.056528

0.0565540.0565800.0566050.0566300.056656

0.0566800.0567060.0567310.0567570.0567820.0568070.0568330.0568580.0568830.0569io

AgeNumber

of years

451452453454455

456457458459460

461462463464465

466467468469470

471472473474475476477478479480

481482483484485

486487488489490

491492493494495496497498499500

Error +

63.163.163.163.163.2

63.263.163,263.263.2

63.263.363.263.363.3

63.363.363.363.463.4

63.463.463.463.463.563.563.563.563.563.5

63.663.663.663.663.663.763.763.763.763.8

63.763.863.863.863.863.863.963.963.963.9

N208/N232

Ratio

0.0222570.0223070.0223570.0224070.022457

0,0225060.0225560.0226060.0226560.022707

0,0227560.0228060.0228560.0229060.0229560.0230060.02305 50.0231050.0231.560.023*07

0.0232570.0233060.0233560.0234060.0234560.0235060.0235560.0236060.0236560.023706

0.0237560.0238060.0238550.0239o60,023956

0.0240o60.0240560.0241050.0241550.024206

0.0242560.0243o60.0243550.0244o50.0244550.0245060.0245560.0246060.0246550.024705

AgeNumber

of years

451452453454455

456457458459460

4614*2463464465

4664674*8469470

471472473474475

476477478479480481432433434435

436437488439490

491492493494495496497498499500

Error +

22,222.322.322.422.4

22.522.522.622,622.722.722,822.822,922.923.023.023.123.123.223.223.323.323.423.423.523.523.623.623.7

23.723.823.823.923.924,024.024.124.124.2

24.224.324.324,424.4

24.524.524.524.624.6

Page 28: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

TABLES FOR THE CALCULATION OF LEAD ISOTOPE AGES

502-600

21

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

"2067*238

Ratio

0.0802060.0805380.0808700.0812020.081534

0.0818680.0822oo0.0825320.0828660,083198

0,0835320.0838640.08419?0.0845310.0848&4

0.0851980.0855310.0858650.0861990.086532

0.0868660.0872020.0875350.0878700.088204

0.0885380.0888730.0892080.0895440.089878

0.0902i30.0905480.0908830.0912i80.091555

0.0918900.0922260.0925610.0928960.093234

0.0935&90.0939060.0942410.0945770.0949i5

0.0952510.0955870.0959250.0962610.096598

Age

Number of

years

502504506508510

512514516518520

522524526528530

532534536538540

542544546548550

552554556558560

562564566568570

572574576578580

582584586588590

593594596598600

Error ±

1.11.11.1XI1.11.11.1XIXI1.2X21.2X2X2X2

X2X2X21.2X2

1.21.21.21.2X2

X21.21.2X2X2

1.21,3X3X3X3

X3X3X3X3X3

X3X3X31.3X3

X3X3X3X3X3

N 207/N235

Ratio

0.6290900.6322&20.6354360.6386210.641809

0.6450050.6482070.6514150.6546270.657850

0.6610750.6643060.6675470.6707920.674043

0.6773030.6805680.6838370.6871160.690399

0.6936880.6969840.7002880.7035950.7069ii

0.7102330.7135610.7168950.7202400.723585

0.7269390.7303010.7336690.7370420.740425

0.7438io0.7472030.7506050.7540i20.757425

0.7608470.7642720.7677060.7711470,774595

0.7780490.7815090.7849760.7884500.791929

Age

Number of

years

502504506508510

512514516518520

522524526528530

532534536538540

542544546548550

552554556558560

562564566568570

572574576578580

582584586588590

592594596598600

Error +

1X31X31X41X41X4

1X51X51X61X61X7

1X71X811.81X81X9

1X912.012.012.112.1

12.212.212.312.312.3

12.412.412.512.512.6

12.612.712.712.712.8

12.812.912.913.013.0

13.113.113.213.213.2

13.313.313.413.413.5

^207/^206

Ratio

0.0569&00.0570ii0.0570620.0571130.057165

0.0572i50.0572670.0573190.0573690.057422

0.0574730.0575250.0575770.0576280.057680

0.0577320.0577840.0578360.0578880.057941

0.0579930.0580440.0580970.0581490.058202

0.0582550.0583070.0583600.0584i20.058465

0.0585180.0585710.0586250.0586780.058730

0.0587840.0588370.0588910.0589450.058997

0.0590510.0591040.0591590.0592i30.059266

0.0593200.0593740.0594270.0594820.059536

Age

Number of

years

502504506508510

512514516518520

522524526528530

532534536538540

542544546548550

552554556558560

562564566568570

572574576578580

582584586588590

592594596598600

Error +

63.964.064.064.064.1

64.164.264.264.264.2

64.364.364.464.364.4

64.464.564.564.664,6

64.764.664.764.764.8

64.864.864.964.964.9

65.065.065.165.165.1

65.165,265.265.365.3

6"5.365.365.465.565.5

65.565.565,665,665,6

N20B/N2 3 2

Ratio

0.0248060.0249050.0250060.0251060.025205

0.0253060.0254060.0255060.0256060.025706

0.0258060.0259070.0260o60.0261070.026207

0.0263070.0264070.0265070.0266080.026709

0.0268080.0269090.0270io0.0271090.0272io

0.0273090.0274io0.0275ii0.0276io0.0277ii

0.0278i20.0279ii0.0280i20.0281120.0282i3

0.0283130.0284i30.0285140.0286150.0287i4

0.0288150.0289i60.0290i60.0291160.029216

0.0293i80.0294i90.0295190.0296 2 o0.029720

Age

Number of

years

502504506508510

512514516518520

522524526528530

532534536538540

542544546548550

552554556558560

562564566568570

572574576578580

582584586588590

592594596598600

Error +

24.724.824.925.025.1

25.225.325.425.525.6

25.725.825.926.026,1

26.226,326.426.526.6

26.726,826.927.027,1

27.227.327.427.527.6

27.727.827.928.028.1

28.228.328.428.528.6

28.728.828.929.029.1

29.229,329.429.529.6

Page 29: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

22 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

602-700

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0.0969360.0972730.0976ii0.0979470.0982850.0986230.0989610.0992990.0996360.0999740.1003130.1006500.1009900.1013270.101666

0.1020050.1023440.1026820.1030220.103360O.l037oo0.1040390.1043790.1047190.1050580.1053980.1057380.1060770.1064180.1067570.1070970.1074390.1077780.1081200.1084590.1088oo0.1091420.1094820.1098240.110165

0.1105060.1108480.1111890.1115310.111872

0.1122i40.1125570.1128980.1132400.113583

AgeNumber

of years

602604606608610612614616618620622624626628630632634636638640642644646648650652654656658660662664666668670672674676678680682684686688690692694696698700

Error ±

1.313131.314

14141,41414

1414141414

1414141414

1414141414

1415151515

1515151515

1515151515

1515151515

1515151516

"207/^235

Ratio

0,7954i70.7989ii0.8024i30.8059210,8094360.8129570.8164860.8200200.8235620.8271130.8306670.8342310.8378oi0.8413770.8449610.8485520.8521500.8557540.8593650.8629850.8666110.8702420.8738840,8775290.8811830.8848460.8885130.8921890.8958720.8995610.9032570.9069630.9106730.9143920.9181170.9218500.9255910.9293390.9330940.9368550.9406270.9444030.9481860.9519790,9557780.9595850.9633970.9672200.9710470.974883

AgeNumber

of years

602604606608610612614616618620622624626628630632634636638640642644646648650652654656658660662664666668670672674676678680682684686688690692694696698700

Error +

13,513.613.613.613.7

13.713.813.813.913.9

14.014.014.014.114.1

14,214.214.314.314.4

14.414.514.514.514.6

14.614.714.714.814.8

14.914.914.915,015.0

15.115.115.215.215.3

15.315.315.415,415.5

15.515.615.615.715.7

N 207/N 206

Ratio

0.0595900.0596440.0596980.0597540.0598080.0598620.0599i70.0599710.0600260.0600810.0601360.0601910.0602460.0603oi0.0603560.0604ii0.0604670.0605230.0605770.0606340.0606890.0607440.0608oo0.0608550.0609i20.0609670.0610230.0610800.0611350.061192

0.0612490.0613040.0613610.0614170.0614740.0615310.0615870.0616440.0617oi0.0617580.0618150.0618720.0619290.0619860.0620440.0621oi0.0621580.0622i60.0622730.062331

AgeNumber

of years

602604606608610612614616618620622624626628630632634636638640642644646648650652654656658660662664666668670672674676678680682684686688690692694696698700

Error +

65.765.765.765.865.865.865.965.966,066.066,066,166.166.166.166.266,266.366.366.466,466,466,466,466.566,566.666,666,666.766.766,766.866,866.966,966.967.067.067.067.167.167.167.267,267.367.367.367.367.4

N208/N232

Ratio

0.0298200.0299210.0300210.0301220.0302230.0303230.0304240.0305250.0306240.0307250.0308250.0309260.0310270.0311270.0312280.0313290.0314290.0315300.0316310.0317320,0318340.0319340.0320350.0321360.0322360.0323370.0324370.0325380.0326390.0327390.0328410,0329420.0330420.0331430.0332430.0333440.0334460.0335460,0336480.0337490.0338500.0339510.0340510.0341520.0342540.0343540.0344550.0345570.0346570.034758

AgeNumber

of years

602604606608610612614616618620622624626628630632634636638640

6426446466486506526546566586*>Q

6^)26*46%6^)86706726746766786BO6B26Q46B6688690692694696698700

Error +

29.729.829.930.030.130.230.330,430,530.630.730.830.931031131231331431531,531631731.831932.032,132,232.332.432.532.632,732.832.933.033.133.233.333.433.533.633.733.833.934.034.134.234.334.434.5

Page 30: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

TABLES FOR THE CALCULATION OF LEAD ISOTOPE AGES

702-800

23

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

N 206//V 238

Ratio

0.1139250.1142680.1146090.1149520.1152950.1156380.1159810.1163250.1166670.1170n

0.1173540.1176970.1180420.1183850.1187290.11907 30.1194i60.1197^10.1201050.1204490.1207950.1211390.1214840.1218290.1221730.1225180.1228630.1232080.1235530.1238980.1242440.1245890.1249340.1252830,1256280.1259740.1263200.1266&50.1270i20.1273590.1277050.12805 20.1283980.1287460.1290930.1294400.1297870.1301350.1304830.130829

AgeNumber

of years

702704706708710

712714716718720

722724726728730732734736738740

742744746748750752754756758760

762764766768770772774776778780782784786788790792794796798800

Error ±

1.616161616

161616161616161616161616161616161617171717171717171717171717171717171717171717181818181818

^207/^235

Ratio

0.9787290.9825780.9864370.9903040.994176

0.9980571001947100584210097441013659101757710215021025439102937910333281037288104125110452241.0492031053191105718910611911065203106922310732491077288108132810853771089439109350410975781101661110575211098491113957

1118071112219011263221.13045911346071.13876311429231.1470941.15127011554591159653116385711680 7011722871176515

AgeNumber

of years

702704706708710

712714716718720

722724726728730732734736738740

742744746748750752754756758760

762764766768770

772774776778780

782784786788790792794796798800

Error ±

15.815.815.815.915.916016.016.116.116.216216.216.316.316.416.416.516.516.616.616.716.716.716.816.816.916.917017.017.117117.117.217.217.3

17.317.417.417.517.517.517.617.617.717.717,817.817.917.918.0

^207/^206

Ratio

0.0623890.0624460.0625050.0625630.062620

0.0626780.0627370.0627940.0628530,0629ii

0.0629700.0630280.0630860.0631450.0632040.0632630,0633220.0633810.0634400.0634990.0635570.0636170.0636760.0637350,0637950.0638550.0639i 40.0639740.0640340.0640940.0641540.0642i40.0642750,0643330.0643940.0644540.0645140.0645760,0646360.0646960.0647570.0648180.0648790.0649390.0650oo0.0650610.0651230.0651830.0652440.065306

AgeNumber

of years

702704706708710

712714716718720

722724726728730732734736738740742744746748750752754756758760

762764766768770

772774776778780

782784786788790792794796798800

Error

±

67.467.467.567.667,667.667.667.667.767.767.867.867.867.967.968.068.068.068.168.168.168.16a268.268.368.368.368.468.468.468.568.568,668.668.6

68.768.768.868.868.868.968.968.968.969.069.069.169.169.169.2

^208/^232

Ratio

0.0348590,0349600.0350610.0351620.0352630.0353640.0354660,0355670,0356690,0357690,0358710,0359710.03607 20,0361740,0362740.0363760.0364770,0365780,0366790,0367800,0368810.0369830,0370840.0371860.0372880,0373880,0374900,0375900.0376920,0377940,0378940,0379960,0380980,0381980,0383oo

0,0384oi0,0385o20,0386o50,0387060,0388o70.0389090, 0390io0,0391i20,03 92 120.0393140,0394i60.0395i70.0396i80,0397200.039821

AgeNumber

of years

702704706708710

712714716718720

722724726728730732734736738740

742744746748750752754756758760

762764766768770

772774776778780782784786788790792794796798800

Error ±

34.634.734.834.935.0

35.135.235.335.435.535.635.735.835.936.0

36.136.236.336.436.536.636.736.836.937.0

37.137.237.337.437.537,637.737.837.938.0

38.138.238.338.438.5

38.538.638.738.838.939.039.139.239.339.4

Page 31: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

24 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

802-900

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0.1311770.1315250.1318720,1322200.1325680.1329170.1332660.1336140.1339&20.1343H0.1346600.1350090.1353570.1357060.1360560.1364050.1367530.1371040.1374530.1378030.1381530.1385010.1388520.1392oi0.139554

0.1399040.1402530.1406050.1409550.1413040.1416560.1420070.1423590.1427io0.143061

0.1434130.1437630.1441160.1444670.1448190.1451720.1455230.1458750.1462280.1465800.1469330.1472850.1476370.1479920.148344

AgeNumber

of years

802804806808810

812814816818820822824826828830

832834836838840

842844846848850

852854856858860862864866868870872874876878880882884886888890892894896898900

Error±

1.81.81.81.8X81.8X81,8X81.81.81.81,81.81.8X8X8X9191.91.919X91.91.9

X91.9191.91.91.9X91.91.91.91.91.9X91.92.02.02.02,02,02.02.02.02.02.02.0

"207/^235

Ratio

1.1807521.1849961.1892481.1935io1,1977771.2020551.2063411,21063612149371.2192491.2235691.227894X2322331,2365761.240929X2452901.2496591.2540373,2584231,262819X2672231,2716351.2760581,2804861.28492512893731293826X2982911,30276613072461.311735X3162371.3207451.3252601,3297881.3343213,3388641.3434161.3479761,352546U57126X361713X3663081.3709i21.3755281.3801521.3847831,3894261,3940751,398732

AeeNumber

of years

802804806808810812814816818820822824826828830832834836838840842844846848850852854856858860862864866868870872874876878880882884886888890892894896898900

Error +

18.018.018.118.118.218.218.318.318.418.418.418.518.518.618.618.718.718.818.818.818.918.919.019,019.119.119.219.219.319.3

19.319.419.419.519.519.619.619.719.719.719,819.819,919.920.020.020.120.120.220.2

N 207/N2Q6

Ratio

0.0653680,0654290.0654910.0655530.0656150.0656760.0657380.0658oo0.0658&20.0659240.0659860.0660480.0661ii0.0661740,0662360.0662980.0663&20,0664240.0664870.0665500.0666120.0666760.0667390.0668030.0668&50.0669290.0669930, 0670550.0671200.0671840.0672470.0673H0.0673750.0674390.0675030.0675&70.0676320.0676960.0677600.0678250.0678890.0679 5 40,0680i90.0680 8 40.0681490.0682i40.0682790,0683440.0684090.068474

AgeNumber

of years

802804806808810

812814816818820822824826828830

832834836838840

842844846848850852854856858860862864866868870872874876878880882884886888890892894896898900

Error +

69.269.269,369.369.469.469.469.569,569,569.569.669.669.769.769,769,869.869.969.969.970.070.070.170,170.170.170.170.270.370.370.370.470.470.470.570.570.570.670.670.670.770.770.870,870.870.970.970.971.0

N208/

Ratio

0.0399230,0400250.0401260,0402280.0403290.0404310,0405330.0406340,0407360.0408370,0409380,0410400.0411410,0412430.0413460.0414470.0415490.0416500.0417520.0418540.0419550.0420570.0421590,0422600,0423620.0424&30.0425660.0426680.0427700.0428720.0429740.0430750,0431770,0432790.0433800.0434820.0435840.0436870.0437890.0438900.0439920.0440950.0441960.0442980.044399

0.0445oi0.0446040,0447050.0448080.0449H

^232

AgeNurrber

of years

802804806808810812814816818820822824826828830832834836838£40842£44£46£48£50£52£54£56essf<SO

f^2FMf*>6f68f70

T72P74P76P78PRO

F82P84P86P88P90

P92P94P96P98900

Error ±

39.539.639.739.839.940.040.140.240.340.440.540.640.740.840,941.041141241.341.441.541.64X741.843,942.042.142.242,342.442,542.642.742,842.943,043.143.243.343,443.543.643,743.843.944.044.144.244.344.4

Page 32: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

TABLES FOR THE CALCULATION OF LEAD ISOTOPE AGES

902-1000

25

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0,1486950.1490490.1494020.1497560.150109

0.1504630.1508170.1511700.1515260.151879

0.1522320.1525870.1529420.1532950.153650

0.1540040.1543600.1547150.1550690.155425

0.1557800.1561350.1564910.1568460.157202

0.1575570.1579i30.1582700.1586250.158982

0.1593370.1596950.1600520.1604070.1607&5

0.1611210.1614780.1618360.1621920.162549

0.1629070.1632640.1636220.1639800.164338

0.1646960.1650540.1654120.1657710.166129

Age

Number of

years

902904906908910

912914916918920

922924926928930

932934936938940

942944946948950

952954956958960

962964966968970

972974976978980

982984986988990

992994996998

1000

Error ±

2.02.02.02.02.0

2.02.02.02,02.0

2.02.02.12.12.1

2.12.12,12.12.1

2.12,12.12.12.1

2.12.12.12.12,1

2.12.12.12.12.2

2.22.22.22.22.2

2.22.22.22.22.2

2.22.22.22.22.2

^207/^235

Ratio

1,4034041,4080791,4127671,417465X4221&9

1,4268811,4316071,4363393,4410781,445831

1,4505911.45535814601421.4649271,469722

1.4745331,4793481,4841 7 21.4890o61,493850

1.4987061.5035661.50844115133201.518213

15231161,5280231.5329441.5378/41,542813

1,5477631.5527201.5576891.5626651,567654

1,5726511,5776561,5826771,5877021,592736

1,5977851.6028401,6079051,6129801,618067

1,6231611.6282631,6333841.6385071,643640

Age

Number of

years

902904906908910

912914916918920

922924926928930

932934936938940

942944946948950

952954956958960

962964966968970

972974976978980

982984986988990

992994996998

1000

Error +

20.220.320.320.420.4

20.520.520.620.620.6

20.720.720.820,820.9

20.921,021,021,021,1

21,121.221,221.321.3

21,421.42X521,521.5

2X62],621,72X72X8

2X821.92X92X922.0

22.022.122.122.222.2

22.322.322.422.422.4

N 207/N206

Ratio

0.0685410.0686060.0686720.0687370.068803

0.0688690.0689340.0690oi0.0690660.069133

0.0691990.0692&50.0693320.0693990.069465

0.0695320.0695980.0696650.0697320.069799

0.0698660.0699330, 0700oi0.0700680.070135

0.0702030.0702710.0703380.0704060.070474

0.0705420, 0706io0.0706780,0707470.070814

0.0708830.0709520.0710200.0710890.071158

0.0712270,0712960.0713640.0714330.071503

0.0715720.0716410,0717n0,0717800.071850

Age

Number of

years

902904906908910

912914916918920

922924926928930

932934936938940

942944946948950

952954956958960

962964966968970

972974976978980

982984986988990

992994996998

1000

Error +

7X07X17X17X17X2

7X271.27X37X37X3

7X47X47X47X57X5

7X67X67X67X67X7

7X77X77X87X87X9

7X972.072.072.072.1

72.172.172.272.272.2

72.372.372.372.472.4

72,572.572.572.672.6

72.672.772.772.772,8

N208/

Ratio

0.0450i20.0451140.0452150.0453180.045420

0.0455210.0456240.0457260.0458270.045931

0.0460320.0461350.0462370.0463380,046441

0.0465430.0466450.0467470.0468490.046952

0.0470550.0471560.0472590.0473610.0474&3

0.0475650.0476670.0477690.0478750.047974

0.0480 7 70,0481800,0482810.0483840.048485

0.0485880.0486910.0487930.0488960.048999

0.0491oo0.0492030.0493050.0494070.0495io

0.0496120.0497160.0498180.0499200.050023

^232

Age

Number of

years

902904906908910

912914916918920

922924926928930

932934936938940

942944946948950

952954956958960

962964966968970

972974976978980

982984986988990

992994996998

1000

Error

±

44.544.644.744.844.9

45.045.145.245.345.4

45.545.545.645.745.8

45.946,046.146,246,3

46.446.546,646.746.8

46.947.047,147,247.3

47.447,547.647.747.8

47.948.04ai48.248.3

48.448.54a648.748.8

48.949.049.149.249.3

Page 33: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

26 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

1002-1100

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0.1664870.1668460.1672030.1675630,1679220.1682820.1686400.1689990.1693590.1697190.1700780.1704380.1707970.1711580.1715180.1718770.1722380.1725980.1729590.1733200.1736800.1740410.1744020.1747640.1751250.1754850.1758470.1762080.1765700.1769320.1772930.1776550.1780i60.1783800.1787420.1791040.1794660.1798300.1801920.1805560.1809i80.1812810.1816450.1820080.1823720.1827350.1830990.1834630.1838250.184190

AgeNumber

of years

10021004100610081010101210141016101810201022102410261028103010321034103610381040104210441046104810501052105410561058106010621064106610681070107210741076107810801082108410861088109010921094109610981100

Error ±

2.22.22.22.22.22.22.22.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.32.42.42.42.42.42.42.42.42.42.42.42.42.42.42.42.42,42.42.42.42,4

N 207/N235

Ratio

1,6487891.6539411,659107X6642841,6694691,6746621,6798721,6850841,6903091,6955481.7007911,7060491,7113151,7165921,7218781.7271781,7324831.7378oi1,7431291,7484711,7538191.7591771,7645481.7699291,7753201,7807211.7861321,7915531,7969881,8024311,8078851,8133511,8188251.8243io1,8298081,8353151.8408311,8463631,8519021,857451I,8630i21,8685871,8741681,8797601,8853681,8909801,896606X9022481,9078941913552

AgeNumber

of years

10021004100610081010101210141016101810201022102410261028103010321034103610381040104210441046104810501052105410561058106010621064106610681070107210741076107810801082108410861088109010921094109610981100

Error +

22.522.522.622.622.722.722.822.822.822.922.923.023.023.123.123.223.223.223.323.323.423.423.523.523.623.623.723.723.723.823.823.923.924.024.024.124.124.124,224.224.324.324.424.424.524.524.524.624.624.7

N 207/N206

Ratio

0.0719200.0719890.0720600,0721290.0721990.0722690.0723400.0724io0.0724800.0725510.0726220.0726920.0727630.0728340.0729050.0729760.0730470.0731190.0731900.0732610.0733330.0734040.0734760.0735470.0736i90.0736920.0737640.0738360.0739080.0739800,0740530.0741250.0741980.0742700.0743430.0744i60.0744890.0745620.0746360.0747080.0747820.0748560.0749290.0750o20.07507 60.0751500.0752240.0752980,0753720.075446

AgeNumber

of years

10021004100610081010101210141016101810201022102410261028103010321034103610381040104210441046104810501052105410561058106010621064106610681070107210741076107810801082108410861088109010921094109610981100

Error +

72.872.872.972.973.073.073.173,173.173.273.273.273.373.373.473.473.473.573.573.573.673.673.673.773.773.873.873.873.973.973.974.074.074.074.174.174.274.274.274.274.374.474.474.474.474.574.574.674.674.6

^208/^232

Ratio

0.0501260.0502270.0503300,0504320.0505350.0506390.0507400.0508430.0509460.0510480.0511510.0512530.0513560.0514600.0515610.0516640.0517670.0518690.0519720.0520740.0521770.0522810.0523830,0524860.0525890.0526910.0527940.0528960.0529990.0531030.0532050.0533080.0534H0.0535130.0536160.0537190.0538230.0539260.0540280.0541310.0542340.0543360.0544400.0545420.0546460,0547490.0548510.0549550.0550580.055160

AgeNumber

of years

10021004100610081010101210141016101810201022102410261028103010321034103610381040104210441046104810501052105410561058106010621064106610681070107210741076107810801082108410861088109010921094109610981100

Error +

49.449.549.649.749.849.950.050.150.250.350,450.550.650.750.850.951.051.15X25X35X45X55X65X75X85X952.052.152.252.352.452.552.552.652.752.852.953.053,153.253.353.453.553.653.753.853.954.054.154.2

Page 34: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

TABLES FOR THE CALCULATION OF LEAD ISOTOPE AGES

1102-1200

27

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0.1845540.1849i80.1852830.1856480.1860ii

0.1863760.1867400.1871060.1874710.187836

0.1882oi0.1885670.1889310.1892970.1896610.1900290,1903940.1907590.1911260.191492

0.1918590.1922240.1925910.1929590.193325

0.1936900.19405 90.1944250.1947930,195161

0.1955280.1958960.1962630.1966320.1969990.1973660.1977360.1981030.1984710.1988400.1992080.1995770.1999450.2003i40.200683

0.20105 20.2014220.2017910.2021600,202531

AgeNumber

of years

11021104110611081110

11121114111611181120

11221124112611281130

11321134113611381140

11421144114611481150

11521154115611581160

11621164116611681170

11721174117611781180

11821184118611881190

11921194119611981200

Error ±

2.42.42.52.52.5

2,52.52.52.52.5

2.52.52.52,52.5

2.52.52.52.52.52.52.52.52.52.5

2.62.62.62.62.6

2.62.62.62.62.6

2.62.62.62.62.62.62.62.62.62.62.62.62.72.72.7

Ratio

1.9192251.9249051.9305981.9363021.9420i6

1.9477411.9534801.9592271.9649851.970758

1.9765371.9823331,9881381.9939531.9997772.0056152.0114662.0173252.0231972.029084

2.0349782.0408842.0468032.0527322.058672

2.0646292,0705912.0765672.0825542.088556

2.0945642.1005902,1066242.1126672,118727

2.1247972,1308782.1369742.1430772.149193

2.1553232.1614642.1676162.1737802.179961

2.1861462.1923462.1985622.2047862.211023

^v235.Age

Number of

years

11021104110611081110

11121114111611181120

11221124112611281130

11321134113611381140

11421144114611481150

11521154115611581160

11621164116611681170

11721174117611781180

11821184118611881190

11921194119611981200

Error ±

24.724.824,824.924.925.025.025.025.125.1

25.225.225.325.325.4

25.425.425.525.525.625.625.725.725.825.8

25.925.925.926.026.0

26,126.126.226.226,3

26.326.326.426.426.526.526.626.626.726.726.726.826.826.926.9

^207/^206

Ratio

0.0755210.0755950.0756690.0757440.075819

0.0758930.0759690.0760430.0761180.076193

0,0762690.0763440.0764200,0764950.076571

0.0766460.0767220.0767990.0768740.076951

0.0770270.0771030.0771800.0772560.077333

0.0774io0.0774860.0775630.0776400.0777i7

0,0777940.0778720.0779490.0780260.078104

0,0781820.0782590.0783380.0784i60.0784940.0785720.0786500.0787290.0788080.078886

0.0789650.0790430.0791230.0792020.079280

AgeNumber

of years

11021104110611081110

11121114111611181120

11221124112611281130

11321134113611381140

11421144114611481150

11521154115611581160

11621164116611681170

11721174117611781180

11821184118611881190

11921194119611981200

Error

±

74.774.774.774.874.8

74.874.974.974.975.075,075.175,175.275.2

75.275.275.375.375.475,475.475.575.575.6

75.675.675.775.775.7

75.875.875975.975.976.076.076,176,176.176,276,276,276.376,3

76,476,476.476,576,5

N208/N232

Ratio

0.0552630.0553670.0554700.0555730.0556750,0557790.0558820,0559840.0560890.056191

0.0562940,0563980,0565oo0.0566030.056707

0.0568io0.0569140.0570160,0571190.057223

0.0573250.0574300,0575330.0576360.057739

0.0578430.0579450.0580490,0581520,058256

0,0583590.0584620.0585650.0586690.058772

0,0588760,0589780.0590820.0591860.059288

0.0593930.0594970.0595990.0597030.059806

0.0599090.0600i30,0601i70,0602200.060324

AgeNumber

of yearr

1102110411061108me1112111411161118112 C

1122112411261128113C

1132113411361138114C

1142114411461148use1152.115411561158116C

1162116411661168117C

1172117411761178118C

1182118411861188119C

119211941196119812 oe

Error

54,354,454.554.654.7

54.854.955.055.155.2

55.355.455.555,655.7

55.855.956,056,156.2

56.356.456,556.656,7

56,856.957.057.157.2

57.357.457.557.657.7

57.857.958.058.158.2

58.358,458,558,658,758,858.959.059,159,2

Page 35: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

28 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

1202-1300

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0.2028990.2032680.2036400,2040o90.2043790.2047510.2051200,2054900.2058620.2062310.2066030.2069740.2073450.2077160.2080880.2084600.2088300.2092030.2095750.2099450.2103190.2106900.2110620.2114350.2118060.2121810.2125530,2129240.2132980.2136710.2140450.2144i70.2147900.2151650.2155380.2159H0.2162860.2166580.2170330.2174070.2177800.2181560.2185300.2189050.2192790.2196530.2200300.2204050.2207790.221155

yv Q.QNumber

of years

12021204120612081210

121212141216121812201222122412261228123012321234123612381240124212441246124812501252125412561258126012621264126612681270127212741276127812801282128412861288129012921294129612981300

Error ±

2.72.72.72.72.72.72.72,72.72.72.72,72.72.72.72.72.72.72.72.7

2.82.82,82.82.82.82.82.82.82.82,82.82.82,82.82,82.82.82,82.82.82,82.92.92.92.92.92,92.92.9

"207/^35

Ratio

2.2172752.2235342.2298092.2360952.2423922.2487012.2550272.2613612.2677052.274067

2.2804392.2868242.2932212.2996302.3060512.3124822.3189342.3253922.3318&02.3383472.3448442.3513552.3578782.3644122.3709592.3775232.3840922,3906782.3972792.4038922.4105162.4171562.4238042.4304692.4371452.4438332.4505342.4572542.4639802.4707202.4774732.4842442.4910262.4978172.5046272.5114482.5182812.5251292.5319882.538864

AgeNumber

of years

1202120412061208121012121214121612181220

12221224122612281230

12321234123612381240

124212441246124812501252125412561258126012621264126612681270127212741276127812801282128412861288129012921294129612981300

Error ±

27,027.027.127,127.227.227.227.327,327.427.427.527,527.627.627,627.727.727.827.827.927.928.028.028.128.128.128.228.228.328.328.428,428.528.528.528,628.628.728.728.828.828.928.928.929.029,029.129.129.2

N 207/

Ratio

0.0793600.0794400.0795180.0795980.0796780.0797570.0798380.0799i80.0799970.080078O.OSOIss0.0802380.0803190.0803990.0804790.0805600.0806420.0807220.0808030.0808850.0809&50.0810470.0811290.0812io0,0812920.0813730.0814550.0815380.0816200.0817020.0817840.0818670,0819500,0820320.0821i50.0821980,0822800.0823640.0824470.0825300.0826140.0826970.0827810.0828640.0829490,0830330.0831i60,0832oo0,0832850.083369

/N

AgeNumber

of years

12021204120612081210121212141216121812201222122412261228123012321234123612381240124212441246124812501252125412561258126012621264126612681270127212741276127812801282128412861288129012921294129612981300

Error

76.576,676,676.776.776.776.876,876.876.976.976,977.077.077.0

77.177.177.277.277,377.377.377.477,477.477.577.577.577.677.677.777.777.877.877.877.977.977.978,078.078.078.178.178,178.278.378.378.378.478.4

N208/

Ratio

0.0604270.0605310.0606330.0607380.060842

0.0609450.0610 4 80.0611520.0612560.061360

0,0614630.0615660.0616700.0617730.0618780.0619820.0620850.0621890,0622910.0623950.0625oo0.0626030.0627070.0628H0, 0629i40.0630! 90.0631220.0632260,0633300.0634330.0635370.0636420.0637450.0638490.0639520.0640560.0641610,0642640.0643680.0644720.0645760.0646810,0647850.0648880,0649920.0650950.0651990,0653050.0654080.065512

//v232Age

Number of

years

120212 0412 OS120°1210

12121214121612181220

12221224122612281230

123212341236123B1240

124212441246124812501252125412561258126012621264126612681270

127212741276127812801282128412S612SB12901292129412*3^12 co13CO

Error

59,359.459.559.559.659.759.859.960.060.160,260.360.460.560.660,760,860,96X06X16X26X36X46X56X66X76X86X962,062.162.262,362,462.562.662.762,862.963,063.163.263.363.463.563,663,763.863.964.064.1

Page 36: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

TABLES FOR THE CALCULATION OF LEAD ISOTOPE AGES

1302-1400

29

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0.2215300.2219060.2222810.2226560.223034

0.2234080.2237860.2241610.2245380.2249i4

0.2252900.2256670.2260440.2264210,226798

0.2271750,2275520.2279310.2283080.2286860.2290640.2294400,2298200.2301960,230575

0.2309540.2313320.2317H0.23209 n0.232467

0,2328470.2332260.2336040,2339840.2343630.2347440.2351220,2355020.2358820,236262

0.2366430,2370220,2374oi0,2377830.2381630,2385430,2389240,2393060,2396870.240068

AgeNumber

of years

13021304130613081310

13121314131613181320

13221324132613281330

13321334133613381340

13421344134613481350

13521354135613581360

13621364136613681370

13721374137613781380

13821384138613881390

13921394139613981400

Error

2.92,92.92.92.9

2,92.92.92.92.9

2.92.92.92.92.9

3.03.03.03.03.03.03.03.03.03.0

3,03.03.03.03,0

3.03.03.03.03.0

3.03.03,13.13.1

3.13.13.13.13.13.13.13.13.13.1

N 207/N23 5

Ratio

2.5457522,5526532.5595642.5664952.573437

2.5803882,5873602.5943382.6013352.608345

2.6153672.6224032.6294552.6365i62.643593

2.6506842.6577922.6649062.6720412.6791882.6863492,6935222,7007i42.7079i52,7151292.7223622.7296072.7368632.7441362.751424

2.7587242.7660412.7733702.7807H2.7880722.7954452.8028312.8102322.8176492.825076

2.8325212.8399812.8474542.8549392,8624452,8699602,8774912.8850392.8926oo2.900174

AgeNumber

of years

13021304130613081310

13121314131613181320

13221324132613281330

13321334133613381340

13421344134613481350

13521354135613581360

13621364136613681370

13721374137613781380

13821384138613881390

13921394139613981400

Error ±

29,229.329.329.429.4

29.429,529.529.629,6

29.729.729.829,829,8

29,929.930.030.030.130.130.230.230,230.3

30.330.430.430.530.5

30.630.630.730.730.7

30.830.830.930.93X0

31.03X13X13X13X23X23X33X33X43X4

N 207/N206

Ratio

0,0834540,0835380,0836230,0837080.083793

0.0838780,0839630,0840490.0841340,0842i9

0, 0843050.0843910.0844770.0845620.084648

0,0847350.0848210.0849070.0849930.085080

0.0851670,0852540,0853400.0854280, 0855150.0856020.0856900.0857770,0858640.0859530.0860400,0861280.0862i70.0863040.086393

0.0864810.0865700.0866580,0867470.086836

0.0869250.0870i40.0871040.0871930.0872820.0873720.0874620.0875510.0876410.087731

AgeNumber

of years

13021304130613081310

13121314131613181320

13221324132613281330

13321334133613381340

13421344134613481350

13521354135613581360

13621364136613681370

13721374137613781380

13821384138613881390

13921394139613981400

Error

78.478.578,578.578.6

78.678.678.778.778,8

78,878.978,978.978,979,079,079.179,179,1

79.279.279.379.379.3

79.479.479,479,579.579.679,679.679.779.7

79.779.879.879,979.9

79.980,080,080,180,1

80,180,280,280,280.3

N208/

Ratio

0,0656160.0657190.0658250.0659280.066032

0.0661360.0662390.0663450.0664490,066552

0,0666570.0667600.0668650.0669700,067073

0.0671770.0672830,0673860.0674900,0675940.0676980.0678040,0679070.0680ii0.0681160,0682190.0683250.0684280,0685330,068637

0.0687400.0688460,0689510.0690540.069159

0.0692630,0693680.0694720.0695760,069680

0.0697860.0698890.0699940.0700980.0702030.0703080.0704120.0705160.0706210,070726

/N232

AgeNumber

of years

13021304130613081310

13121314131613181320

13221324132613281330

13321334133613381340

13421344134613481350

13521354135613581360

13621364136613681370

13721374137613781380

13821384138613881390

13921394139613981400

Error

64,264.364.464.564.6

64.764.864.965.065,1

65.265.365.465.565.6

65.765,865,966.066.166.266.366,466.566.566.666.766,866.967.0

67.167.267.367.467.5

67.667.767.867,968.0

68,168.268.368.468,5

68.668.768.868.969.0

Page 37: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

30 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

1402-1500

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0.2404480.2408310.2412H0.2415940.2419750,2423570.2427380.2431210.2435030.2438860.2442&80.2446520.2450340.2454i50.2458oo0.2461810.2465660.2469480.2473320.2477150.2480990.2484820.2488660.2492500.2496340.2500i90.2504oi0.2507870.2511720.2515570.2519410.2523250.2527H0,2530950.2534800,2538660.2542510.2546380.2550220.2554090,2557960,2561810,256569

AgeNumber

of years

140214041406140814101412141414161418142014221424142614281430

14321434143614381440

14421444144614481450

145214541456145814601462146414661468147014721474147614781480148214841486

0,256954 14880.257340 14900.257728 14920.2581130.2585oo

14941496

0.258887 14980.259274 1500

Error ±

3.13.13.13,13.13.13.13.13.13.13.23.23.23.23.23.23.23.23.23.23.23.23.23.23.2

3.23.23.23.23.23.23.23,33.33.33.33.33.33,33.33.33.33.33,33.33.33.33.33.33.3

^207/^235

Ratio

2.9077672.9153722.9229912.9306302.9382782.9459412.9536242,9613i52,9690242.9767502.9844892.9922443.0000i53.0078oo3.0155973.0234U3.0312453.0390903.0469493.0548293.0627193.0706253.0785523.0864863.094438

3.1024io3.1103933.1183893.1264io3.1344403,1424843.1505483.1586263.1667183.1748303.1829543.1910943.1992483.2074233.2156H3.2238143.2320373.2402733.2485233.2567953.2650793,2733793.2816983.2900293.298375

AgeNumber

of years

140214041406140814101412141414161418142014221424142614281430

14321434143614381440

14421444144614481450

14521454145614581460

14621464146614681470

147214741476147814801482148414861488149014921494149614981500

Error

3X53X53X63X63X63X731.731.83X83X93X932.032.032.032.132.132.232.232.332.332,432.432.432.532.5

32.632.632.732.732.832.832.932.932.933.033.033.133.133.233.233.333.333.333.433.433.533.533.633.633.7

N 207/N 206

Ratio

0.0878220,0879ii0.0880o20.0880920.0881830.0882740.0883650.0884560.0885470.0886380.0887290.0888200.0889i20.0890o40.0890950.0891880.0892790.0893720.0894640.0895570.0896490.0897420.0898350.0899280.090021

0.0901x30.0902080.0903oo0.0903940.0904870.09058X0.0906750.0907690.0908640.0909580.0910 5 20.0911470.0912410.0913360.0914300.0915250.0916210.0917150.0918H0.0919o70.0920o20.0920980.0921940.092290

AgeNumber

of years

14021404140614081410

141214141416141814201422142414261428143014321434143614381440

14421444144614481450

145214541456145814601462146414661468147014721474147614781480148214841486148814901492149414961498

0.092386 1500

Error

80.380.480.480.480.580,580.680.680.680.780.780.780.880.880.880.980.98X08X08X18X18X18X28X28X2

8X381.38X38X48X48X58X58X68X68X68X78X78X78X88X88X88X98X982.082.082.082.182.182.282.2

N208/

Ratio

0.0708300.0709340.0710390.0711440.071248

0.0713530.0714580.0715620.0716670.0717710.0718760.0719800.0720850.0721900.0722950.0723990.0725040.0726090.0727140.0728190.0729240.0730290.0731340.0732370.0733430.0734480.0735520.0736570.0737620.0738670,0739720.0740760.0741820.0742870.0743910.0744960.0746oi0.0747060.0748H0,0749i50.0750210.0751260.0752300.0753350.0754400.0755460.0756510.0757550.0758610.075966

/N232

AgeNumber

of yearr

1402140/1140614 OP1410

141214141416141P1420

1422142/11426142P1430

143214311436143P1440

1442144/1144614481450

1452145^1456145P1460

14621461146614681470147214741476147P148014821484148614881490149214911496149P1500

Error

69.169.269,369.469.569.669,769.869.970.070.170,270,370.470.570.670,770.870.97X0

7X17X271.37X47X5

7X67X77X87X972.0

72.172.272.372.472,572.672.772,872.973.0

73.173.273.373.473.573.573.673.773.873.9

Page 38: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

TABLES FOR THE CALCULATION OF LEAD ISOTOPE AGES

1505-1750

31

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0.2602430.2612110.2621800.2631510,2641200.2650940.2660670.2670390.2680i30.2689890.2699640.2709410.2719170.2728950.2738720.2748520.2758330.2768140.2777960.2787770.2797610.2807450.2817290.2827140.2837020.2846880.2856760.2866630.2876530.2886420.2896320.2906240.2916160.2926io0.2936020.2945980.2955920.2965890.2975840.2985840,2995810,3005800,3015810.3025800.3035810.3045840,3055880.3065910.3075950.308599

AgeNumber

of years

1505151015151520152515301535154015451550

1555156015651570157515801585159015951600

1605161016151620162516301635164016451650

1655166016651670167516801685169016951700

1705171017151720172517301735174017451750

Error ±

3.33,33,43.43.4

3.43,43.43.43.43.43.53.53.53.53.53,53.53.53.5

3.63.63.63.63.63.63.63.63.63.73.73.73.73.73.73.73,73.73.83.83.83.83.83.83.83.83.83.93.93.9

"207/^235

Ratio

3.3193223.3403693.3615203.3827723.4041253.4255853.4471493.4688213.4905993.5124733.5344633.5565573.5787613.6010733.6234893.6460i93.6686563.6914063.7142693.7372353.7603203.7835i63.8068233.8302463.8537783.8774303.9011983.9250823.9490793.9731903.9974244.0217754.0462444.0708344.095538

4.1203704.1453184.1703924.1955874.2208984.2463424.2719054.2975934.3234074.3493424.3754084.4016024.4279224.4543744.480945

AgeNumber

of years

1505151015151520152515301535154015451550

1555156015651570157515801585159015951600

160516101615162016251630163516401645165016551660166516701675168016851690169517001705171017151720172517301735174017451750

Error i

33.833.934.034.134.234.334,434.634.734.834.935.035.135,235.335,535.635,735.835,9

36.036.136,236.436.536.636.736.836.937.037.137,337,437.537.637.737.837,938.038,138.338,438.538.638.738.838.939.039.239.3

N 207/

Ratio

0.0926260.0928680.0931110.0933540.0935980.0938420.0940880.0943350.0945820.0948290.0950780.0953280.0955780.0958300.0960820.0963350.0965880.0968430.0970980.0973550.0976120.0978700.0981280.0983880.0986480.0989io0.0991720.0994350.0996990.0999640.1002300.1004960.1007640.1010320.1013010.1015710.1018430.1021i40.1023880.1026600.1029350.1032110.1034870.1037650.1040430,1043220.1046020.1048830,1051650,105448

'"206

AgeNumber

of years

1505151015151520152515301535154015451550

1555156015651570157515801585159015951600

1605161016151620162516301635164016451650

16551660166516701675168016851690169517001705171017151720172517301735174017451750

Error +

82.382,482.582.682.782.882,983,083,183.2

83.383.483.583,683.783.883.984.084.184,2

84.384.384.484,584.684.784.884.985.085.185.285.385.485.585.685.785.885,986.0B6.186.286.386.486.586.686.786.886.987.087.1

^208/^232

Ratio

0,0762290,0764910,0767540.0770i70.0772790.0775420,0778060.0780680.0783310.0785950.0788570.0791210,0793840.0796490.0799120.0801760,0804390.0807020.0809660,0812300.0814940.0817580.0820220.0822860,0825500,0828i40.0830780.0833430.0836080.0838730.0841370,0844oi0,0846660,0849310.0851960.0854600.0857250.0859900.0862550.0865210.0867860.0870510,0873170.0875830.0878490.0881i40.0883800.0886450.0889io0.089176

AgeNumber

of years

1505151015151520152515301535154015451550

1555156015651570157515801585159015951600

1605161016151620162516301635164016451650

16551660166516701675168016851690169517001705171017151720172517301735174017451750

Error ±

74.274.474,774.975.275,475.775.976.276,476.776.977.177.477.677.978.178.478.678.979.179.479.679.980.180.480,680.881181381.683,882,182.382.682.883.183.383,683.884.084.384.584.885,0

85.385,585,886.086.3

Page 39: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

32 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

1755-2000

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0,3096o60,3106i40.3116210.3126300,313637

0.3146480.3156580.3166710.3176820.3186960.3197080.3207230.3217390.3227560.3237710.3247890,3258070.3268270.3278480.3288&7

0.3298900.3309ii0.3319350.3329590,3339840.3350o90.3360350.3370620,33808 90.3391i90.3401470.3411790.3422090.3432410.344274

0.3453080,3463410.3473770.3484ii0.349450

0.3504880.3515250.3525&40.3536040.354645

0,3556850,3567280.3577710.3588i60.359859

AgeNumber

of years

17551760176517701775

17801785179017951800

1805181018151820182518301835184018451850

18551860186518701875188018851890189519001905191019151920192519301935194019451950

1955196019651970197519801985199019952000

Error ±

3.93.93.93.93.9

3.94.04.04.04.0

4.04.04.04.04.0

4.14.14.14.14.1

4.14.14.14.14.24.24.24.24,24.2

4.24.24.24.34.34.34.34.34,34.3

4,34.34.44.44.4

4.44.44.44.44.4

^207/^235

Ratio

4.5076534.5344934.5614&24.5885544.615787

4,6431534.6706504.6982824.7260434.753945

4.7819844,8101564.8384684.8669i34.895498

4.9242304.9530974.9821065.0112505.040542

5.0699765.0995545.1292755.1591365,189152

5,2193075.2496135.2800685.3106&45.3414i4

5.3723155,4033655.4345685,4659i55.497425

5.5290845.5608985.5928725.6249875.657274

5.6897io5.7223io5.7550&65.7879765.821053

5.8542915.8876915.9212525.9549705,988862

AgeNumber

of years

1755176017651770177517801785179017951800

18051810181518201825

18301835184018451850

1855186018651870187518801885189018951900

19051910191519201925

19301935194019451950

1955196019651970197519801985199019952000

Error +

39.439,539.639.739.8

39.940.140.240.340.4

40.540.640.740.841.0

41.141.241.341.441.5

41.641.743,942.042.1

42.242.342.442.542.6

42.742.943.043.143.243.343.443.543.643.843.944.044,144.244.3

44.444.544.744.844.9

N 207/N2Q6

Ratio

0.1057320.1060i60.1063020.1065880,106877

0.1071650.1074540.1077440.1080360.108328

0.1086220.1089i60.1092110.1095070.109805

0.1101030,1104030.1107030.1110040.111307

0.1116090.1119i40.1122i90.1125250.112833

0,1131410.1134510,1137610.1140730.1143850.1146990,1150i30,1153290,1156450,115963

0.1162820.1166020.1169220,1172450.117567

0.1178910.1182i70,1185430.1188700.119199

0.1195290.1198590.1201910.1205240.120858

AgeNumber

of years

17551760176517701775

17801785179017951800

1805181018151820182518301835184018451850

18551860186518701875188018851890189519001905191019151920192519301935194019451950

1955196019651970197519801985199019952000

Error

±

87.287.387,487.587.6

87.787.887.988.088.1

88.288.388.488.588,6

88.788.888.989.089.1

89.289.389.489.589.689.789.889.990.090.1

90.290.390,490.590.6

90.790.890.991.091.1

91.291,391.491.591.6

93,791,89X992.092.1

^208/^232

Ratio

0,0894420,0897080.0899740.0902400,0905060.0907720,0910380.0913050.0915720,091839

0.0921040.0923710,0926370,0929040.093170

0.0934370.0937040.0939710.0942380,094505

0.0947720.0950390.0953060.0955750.095842

0.0961090.0963770.0966440.0969i30.0971800,0974480.0977170,0979840.0982520.098520

0,0987880,0990560.0993240.0995930.0998&2

0.1001300.1003980.1006&80.1009360.1012050.1014730.101742O.l020io0,1022790,102549

AgeNuirber

of years

1755176017651770177517801785179017951£00

18051£10IE 1518201£251£301£35U401£45If50

If551£60lf<>5If701£75IfBO1PB5If901P951°00

19051910191519201°25

1°301935194019451950

1955196019651970197519801985199019952000

Error ±

86,586.887.087.387.587.7sao88,288.588.789.089.289.589.790.0

90.290.590.791093,291.491.791.992.292.4

92.792.993.293.493.793.994.294.494,694.9

95.195.495.695.996.1

96.496.696.997.197.497,697.998.198.398.6

Page 40: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

TABLES FOR THE CALCULATION OF LEAD ISOTOPE AGES

2005-2250

33

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0.3609050.3619510.3629980.36404?0.365094

0.3661440.3671940.3682450.3692960.370349

0.3714030.3724580.3735ii0.3745690,375624

0,3766820.3777420.3787990.3798590.380921

0.3819820,3830430.3841o90.3851720.386236

0.3873030.3883680.3894360.3905040.3915 73

0.3926430.3937i40.3947830.3958570.3969 3 o

0.3980o50.3990780,4001540.4012310.402307

0.4033870.4044640.4055460.4066250.407706

0.4087880.4098730.4109560.4120410,413125

AgeNumber

of years

20052010201520202025

20302035204020452050

20552060206520702075

20802085209020952100

21052110211521202125

21302135214021452150

2155216021652170217521802185219021952200

2205221022152220222522302235224022452250

Error +

4.44.54.54.54.5

4.54.54.54.54.5

4.64,64.64.64.6

4.64.64.64.64.7

4.74.74.74.74.7

4.74.74.74.84.8

4.84.84.84.84.8

4.84.84.94.94.9

4.94.94.94.94.9

4.95.05.05.05.0

L N 207/N 235

Ratio

6, 0229i86.0571406.0915266.1260766.160799

6.1956956.2307586.2659926.3013916.336972

6.3727206.4086486.4447496.4810i96.517473

6,5541o46.5909i26.6279046,6650646.7024i4

6.7399466.7776626.8155616.8536386.891908

6.9303646.9690057.0078397.0468527.086061

7.1254657,1650587.2048447.2448i97.284996

7.3253657.3659 3 37.4066987.4476557.4888i9

7.5301857.5717517,6135187.6554857.697660

7.7400417.7826287.8254267.8684227.911637

AgeNumber

ofyears

20052010201520202025

20302035204020452050

20552060206520702075

20802085209020952100

21052110211521202125

21302135214021452150

21552160216521702175

21802185219021952200

22052210221522202225

22302235224022452250

Error±

45.045.145.245.345.4

45.645.745.845.946.0

46.146.246.346.546.6

46.746.846.947.047.1

47.247.347.547.647.7

47.847.948.048.148.2

48.448,548.648.748.8

48.949.049.149.349.4

49,549.649.749.849.9

50.050.250.350.450.5

N 207/N206

Ratio

0.1211930.1215300,1218670.1222050.122545

0.1228860.1232280.1235710.1239i60.124261

0.1246070.1249550.1253050.1256540.1260o6

0.1263580.1267H0.1270670.1274230.127779

0.1281380.1284980,1288580,1292200.129584

0.1299480.1303140.1306810.1310490.131419

0.1317890,1321610.1325350.1329090.133285

0,1336610.1340400.1344i90.1348oo0.135182

0.1355650.1359510.1363360.1367230,137112

0,1375020.1378930.1382860,1386790.139075

AgeNumber

of years

20052010201520202025

20302035204020452050

20552060206520702075

20802085209020952100

21052110211521202125

21302135214021452150

21552160216521702175

21802185219021952200

22052210221522202225

22302235224022452250

Error +

92.292.392.492.592.6

92.792.892.993.093.1

93.293.393.493.593.6

93.793.893.994.094.1

94.294.394.494.594.6

94,794.894.995.095.1

95.295.395.595.695.7

95,895.996,096.196,2

96.396.496.596.696.7

96.896.997.097,197.2

N208/N 232

Ratio

0.1028180,1030870.1033560.1036260,103895

0.1041660,1044350.1047040.1049740.105243

0.1055i40.1057830.1060530.1063220.106593

0,1068630.1071330,1074020.1076740.107944

0.1082140.1084860,1087560.1090260.109296

0.1095680.1098380.1101080,1103800.110652

0,1109220.1111940,1114650,1117380.112008

0,1122790.1125510,1128220.1130950.113366

0.1136370,1139o90.1141810,1144530,114724

0.1149960.1152690,1155400.1158140.116087

AgeNumber

ofyears

20052010201520202025

20302035204020452050

20552060206520702075

20802085209020952100

21052110211521202125

21302135214021452150

21552160216521702175

21802185219021952200

22052210221522202225

22302235224022452250

Error +

98,899,199,399.699.8

100,1100.310061008101,1

101.3101.5101,8102.0102.3

102.5102.8103.0103.3103.5

103.8104.0104.3104.5104.8

105.0105.2105.5105.7106.0

106.2106.5106.7107.0107.2

107.5107.7108,0108.2108.5

108.7108,9109.2109.4109.7

:.09.9110,2110.4110.7110.9

Page 41: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

34 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

2255-2500

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

"206/^238

Ratio

0.4142ii0.4153oo0,4163860.4174770.4185&50.4196580.4207470.4218400.4229320.4240260.4251210.4262i70.4273i30.4284090.4295o90.4306080,4317070.4328070.4339io0, 4350i20,4361i60,4372i90,4383250.4394300.440537

0.4416430.4427520.4438&20.4449710.4460820.4471930.4483070.4494i90.4505350.4516480.4527650.4538820.4549980,4561i70,4572360.4583570.4594790,4606o20.4617230,4628490.4639720.4650970.4662240.4673520,468478

AgeNumber

of years

22552260226522702275228022852290229523002305231023152320232523302335234023452350

235523602365237023752380238523902395240024052410241524202425243024352440244524502455246024652470247524802485249024952500

Error +

5.05.05.05.05.05.15.15.15.15.15.15.15.15.15,25.25.25.25.25.25,25.25.25.3

. 5,35.35.35.35.35.35.35.35.45.45.45.45.45.45.45.45.45.55.55.55.55.55.55.55.55.5

. N 207

Ratio

7.955067.998708.042548.086608,13088

8.175378.220o88.265oi8.310i48.355518.401io8.446918,492948.539i98.585678.632388.679328.726498.773878.821508.869368.917458.965779.014339.063i29.112i69.161439.210959.260709.310&99.360939.411429.462i69.513i39.564369.615849.667569.719559.771779.824269.877oo9.930oo9.98327

10.0367710,0905510.1446010.1989010.2534710.3083010.36340

7^235

AgeNumber

of years

225522602265227022752280228522902295230023052310231523202325233023352340234523502355236023652370237523802385239023952400240524102415242024252430243524402445245024552460.24652470247524802485249024952500

Error +

50.650.750,850,95X15X25X35X45X551.65X75X85X952.152.252.352,452.552.652.752.853,053.153.253.353.453.553.653.753.954.054.154.254.354.454.554.654,854.955.055.155.255.355.455.555.755.855.956.056.1

N 207/

Ratio

0.1394720.1398690.1402&90,1406690.1410710.1414740.1418790.1422850.1426930,1431o20.1435i20,1439230.1443370.1447510.1451670.1455840.1460030.1464230.1468440.1472&70.1476910.1481i80.1485440.1489730.1494030.1498350,1502680.1507030.1511390.1515770,1520i60.1524560,1528990.1533410.1537870.1542340.1546820,1551320.1555830,1560360.1564900.1569450.1574030.1578&20.1583220.1587840.1592480.1597i30,1601800,160649

^206

AgeNumber

of years

22552260226522702275228022852290229523002305231023152320232523302335234023452350

235523602365237023752380238523902395240024052410241524202425243024352440244524502455246024652470247524802485249024952500

Error

±

97.397.497.597.697.797.897.998.098.198.298,398.498.598.698.798.898,999,099,199.399,399,599.699.799.899.9

100,0100.1100.2100.3100.4100.5100.6100.7100.8100.910X0101,110X210X310X410X510X610X810X9102,0102.1102.2102.3102.4

N208/W 232

Ratio

0.1163600.1166320.1169040.1171760.1174500.1177220.1179950.1182&70,1185400.1188130.1190860.1193590.1196320.1199070.1201800.1204530.1207270.12lOoi0,1212740.1215480,1218220.1220950.1223690,1226430, 1229160.1231910.1234640.1237390.1240i40.1242880.1245620,1248370.1251130.1253870.1256610.1259360.1262io0.1264850.1267&00.127036

0.1273io0.1275850.1278&00.1281370,1284ii0.1286870.1289&30.1292*90.1295150.129790

AgeNumber

of years

22552260226522702275228022852290229523002305231023152320232523302335234023452350

23552360236523702375238023852390239524002405241024152420242524302435244024452450

2455246024652470247524802485249024952500

Error +

111.211X411X711X9112,1112.4112.6112.9113.1113,4113.6113.9114.1114.4114,6114.9115.1115.4115.6115.8nea116.3116.6116.8117.1117.3117.6117.8118.1118.3118.6118.8119.0119.3119.5119.8120.0120.3120.5120.812X012X312X512X8122.0122.3122.5122.7123.0123.2

Page 42: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

TABLES FOR THE CALCULATION OF LEAD ISOTOPE AGES

2510-3000

35

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0.4707370.4729990.4752660.4775350,4798o60.4820830.4843630.4866440.4889330.4912220.4935i50.4958i30.4981i30.5004i80.5027260.5050370.5073520.5096710.5119920.5143i80.5166470.5189810.5213i60.5236560.5260oo0.5283490.5306980.5330520.5354io0.5377710.5401370.5425060.5448780.5472540.5496340.5520i70.5544060.5567960.5591900.5615880.5639930.5663970,5688050.5712160.5736350.5760550.5784790.5809070.5833390.585775

AgeNumber

of years

25102520253025402550256025702580259026002610262026302640265026602670268026902700271027202730274027502760277027802790280028102820283028402850286028702880289029002910292029302940295029602970298029903000

Error ±

5.65.65.65.65.75.75.75.75.75^85.85^85.85.95.95.95.95.96,06.06.06.06.16.16.16.16.16.26,26.26,26.36.36.36.36.36.46,46.46,46.56,56.56,56.56,66.66.66.66.7

^207

Ratio

10.4744210.5865010.6997010.8139910.9294011.0459411.1636111.282441X4024311,5235811.6459311.769471X8942112.020i912.1473712,2758112.4055012.5364612.6687012.8022212.9370613.0732113.2106913.3495313.4897013.6312513.7741713.9185114.0642614.2114114.360o214.510o614.6615914.8145914.9690815.1250815.2826015.4416715.6022915.7644715.9282616.0936116.2606116.4292316.5994916.7714316.9450217.1203417.2973717.476io

/^235

AgeNumber

of years

25102520253025402550256025702580259026002610262026302640265026602670268026902700271027202730274027502760277027802790280028102820283028402850286028702880289029002910292029302940295029602970298029903000

Error ±

56,356.556.857.057.257.457.757.958.158.358.658.859.059.259.559.759.960.160.460.660.86X06X36X56X76X962.262.462.662.863.163.363.563.764.064.264.464.664.965,165.365.565.866.066.266.466.666.967.167,3

N 207/N 206

Ratio

0.1615910.1625390.1634930.1644550.1654230.1663970.1673780.1683670.1693610.1703630.1713720.1723870.1734090.1744390.1754750.1765i90.1775700.1786280.1796940.1807670.1818470.1829350.1840300.1851330.1862440.1873610.1884880.1896220.1907640.1919130.1930710.1942360.1954io0.1965920.1977820.1989800.2001860.2014020.2026260.2038580.2050970.2063470.2076050.2088730.210148

0.2114320.2127260,2140280,2153400,216660

AgeNumber

of years

25102520253025402550256025702580259026002610262026302640265026602670268026902700271027202730274027502760277027802790280028102820283028402850286028702880289029002910292029302940295029602970298029903000

Error

±

102,6102.8103.0103.2103.4103.6103.8104.1104.3104.5104.7104,9105,1105.3105.5105.7106,0106.2106.4106.6106.8107.0107.2107.4107.7107.9108.1108.3108.5108.7108.9109,1109,4109.6109.8110.0110.2110,4110.6110.911X111X311X511X711X9112.1112.4112.6112.8113.0

N208/N 232

Ratio

0.1303410.1308930.1314440.1319970.1325500.1331040.1336570.1342io0.1347630.1353170.1358710.1364280.1369820,1375370,1380920.1386470.1392030.1397600.1403160.1408740.1414300.1419880.1425460.1431030,1436610.1442190.1447780.1453380.1458960.1464560.1470i60.1475750,1481360,1486950.1492570.1498i80.1503810.1509420.1515030.1520650.1526270.1531920.1537540.1543170.1548800.1554450.1560080.1565720.1571380.157704

AgeNumber

of years

251C252C253C254C255C256C257C258C259C26002610262026302640265026602670268026902700271027202730274027502760277027802790280028102820283028402850286028702880289029002910292029302940295029602970298029903000

Error +

123,7124.2124.7125.2125.7126,2126,7127,2127.7128.2128.7129.2129.6130.1130,613X113X6132.1132,6133.1133.6134.1134.6135.1135.6136.1136.5137.0137,5138.0138.5139.0139.5140.0140.514X014X5142.0142.5143,0143.5143.9144.4144.9145.4145.9146,4146.9147.4147,9

Page 43: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

36 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

3010-3500

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0.5882i30.5906560.5931030.5955530.5980o60.6004&40.6029280.6053930.6078&20.6103350.6128ii0.6152920.6177770.6202&60.6227570.6252550.6277520.6302560.6327&50.6352750,6377910.6403io0.6428330.6453600.6478910.6504250.6529&50.6555060.6580520.6606oo

0.6631550.6657140.6682760.6708430.6734120.6759850.6785640.6811480.6837330.6863230.6889i60.6915130.6941i40.6967210.6993300.7019440.7045610.7071830.7098080.712439

AgeNumber

of years

3010302030303040305030603070308030903100

31103120313031403150316031703180319032003210322032303240325032603270328032903300

3310332033303340335033603370338033903400

3410342034303440345034603470348034903500

Error ±

6,76.76.76,76.86.86.86.86.96.9

6.96.96.97.07.07,07.07.17.17.17.17.17.27.27,27.27.37.37.37.3

7.37.47.47.47.47.57.57.57.57.57.67.67.67.67,67.77.77.77.77.8

N 207/N 235

Ratio

17.6566117.8388518.02289182087418.39637

18.5858618.7771818,970 4 o19.1655019.3624819.5614119.7622719.965io20.1699220.3767120.5855520.7964121.0093521.224372X441462X660702X882o622.1056122.3313322.5592422.7894023.0217923.2564623.4934423.7327023.9743224.2182924.4646524.7134224.964&0

25.2182625.4743825.733oi25.994i826.2578726.5241626.7930327.0645527.3387327.6155527.895H28.1773728.4624128.7502429.04086

AgeNumber

of years

30103020303030403050306030703080309031003110312031303140315031603170318031903200321032203230324032503260327032803290330033103320333033403350336033703380339034003410342034303440345034603470348034903500

Error ±

67.567.868.068.268.468.768.969.169,369.669.870.070.270.570.770.97X171.47X67X872.072.372.572.772.973.273.473.673.874.174.374.574.775,075.275.475.675.876.176.376.576.777.077.277.477.677,978.178.378.5

^2077

Ratio

0.2179910.2193300.2206780.2220 3 70.2234040.2247820.2261&80.2275640.2289710.2303870.2318i40.2332490.2346960.2361520.2376190.2390950.2405830.2420810.2435890.2451080.2466380.2481780.2497290.2512920.2528650.2544490.2560440.2576510.2592700.2609oo0.2625410.2641930.2658570.2675330.269221

0,2709210,2726330,2743560.2760930.2778410.2796020.2813760.2831620,2849610.2867720.2885960.2904340.2922840.2941480,296024

//V206

AgeNumber

of years

301030203030304030503060307030803090310031103120313031403150316031703180319032003210322032303240325032603270328032903300

33103320333033403350

33603370338033903400

3410342034303440345034603470348034903500

Error

±

113.2113,4113.7113.9114.1

114.3114.5114.7115.0115.2115.4115.6115.8116.0116.3116.5116.7116.9117.1117,3117.6117,8118.0118.21184118,7118.9119.1119.3119,5119.8120,0120.2120.4120.6120.9121.112X312X512X712X9122.2122.4122.6122.8123.1123.3123.5123,7123.9

N208/N 232

Ratio

0.1582680,1588330.1593990.1599&60.1605310.1610980.1616&50.1622330.1628oo0.1633680.1639360.1645040.16507 20.1656420.1662ii0,1667800.1673490.1679200.1684900.1690600.1696310.1702030.1707740.1713460,1719i70.1724890.1730620.1736350.1742080.1747820.1753540.1759280.1765020.1770770.1776510.1782260.1788020.1793770.1799550.180530

0.1811060.1816830.1822600.1828390.1834150.1839920.1845710.1851480,1857270.186307

AgeNumber

ofyear?

301C302C303G304C305C306C307C308C309C310C

311C312 C313C314C315C316C317C318C319C320C321032203230324032503260327032803290330033103320333033403350336033703380339034003410342034303440345034603470348034903500

Error ±

148.4148.9149.4149.9150.4150.8151.315X8152.3152.8153.3153.8154.3154.8155.3155.8156.3156,8157.3157.7158.2158.7159,2159.7160.2160.7161.216X7162.2162.7163.2163.7164.2164.6165.1165.6166.1166.6167.1167.6168.1168.6169.1169,6170.1170.6171,117X5172.0172,5

Page 44: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

TABLES FOR THE CALCULATION OF LEAD ISOTOPE AGES

3510-4000

37

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Ratio

0.7150730.7177120,7203530.7229970.725648

0.7283040.7309610.7336230.7362920.7389&1

0.7416370.7443160.7469980.7496860.752377

0.7550700.7577700.7604740,7631820.765894

0.7686io0.7713290,7740560.7767840.779517

0.7822540.7849960.7877400.7904890.793244

0.7960oi0.7987640.8015300.8043010.807077

0.8098570.8126410.8154300,8182220.8210i8

0.8238170.8266230.8294320.8322470.835065

0.8378870.8407150.8435460.8463820.849221

AgeNumber

of years

35103520353035403550

35603570358035903600

36103620363036403650

36603670368036903700

37103720373037403750

37603770378037903800

38103820383038403850

38603870388038903900

39103920393039403950

39603970398039904000

Error ±

7.87.87.87.87.9

7.97.97.98.08.0

8.08.08.08.18.1

8.18.18.28.28,2

8.28.28.38.38.3

8,38.48.48.48.4

8.48.58.58.58.5

8.68,68,68.68.6

8.78.78,78.78.8

8.88.88.88.88,9

N 207/N 235

Ratio

29.3343429.630&529.9299030.2320330.53715

30.8452631.1563331.4704831.7876632,10798

32.4314332.758oo33.0877933.4207833.75705

34.0966034.4394534.7856735.1352335.48826

35.8447336,2046436.568ii36,9350937.30569

37.6799238.0577638.4393338.8245939.21365

39.6065240.0031840.4037540.8082041,21664

41.6290742.0454942.4660242.890&243.3194 o

43.7523844.1895344.631oi45.0767545.52689

45,9814446.4403746.9038347.371 7 847.84434

AgeNumber

of years

35103520353035403550

35603570358035903600

36103620363036403650

36603670368036903700

37103720373037403750

37603770378037903800

38103820383038403850

38603870388038903900

39103920393039403950

396039703Q8039904000

Error ±

78,879.079.279.479.7

79.980.180,380.680.8

8X081.281.58X781.9

82.182.482.6 82.883.0

83.383.583.783.984.2

84.484.684.885.085.3

85.585.785.986.286.4

86.686.887.187.387.5

87.788.088.288,488.6

88.989.189.389.589.8

N 207/N206

Ratio

0.2979i40.2998170.3017350.3036660.3056io

0.3075680.3095400.3115270.3135260.315542

0.3175700.3196140,3216720.3237450.325833

0.3279360.3300530.3321860.3343340.336497

0.3386760.3408?!0.3430800.3453060.347548

0.3498060.3520800.3543710.3566780.3590oi

0,3613420.3636980.3660730.3684630.370871

0.3732960.3757390.3781990.3806770.383173

0.3856880.3882200.3907700.3933380.395925

0,3985320.4011550,4037990.4064610.409143

AgeNumber

of years

35103520353035403550

35603570358035903600

36103620363036403650

36603670368036903700

37103720373037403750

37603770378037903800

38103820383038403850

38603870388038903900

3910392039303940

Error +

124.2124.4124.6124.8125.0

125.3125.5125.7125,9126,2

126.4126.6126.8127,0127,3

127.5127,7127.9128.2128.4

128.6128.8129.0129.3129.5

129.7129.9130.2130.4130,6

130.813X113X313X5131.7

132.0132.2132.4132.6132.9

133,1133.3133.5133,8

3950 134.0

3960 134.23970 134.43980 134,73990 134.94000 135.1

N208/N232

Ratio

0.1868850.1874660.1880450.1886250.189206

0.1897850.1903660.1909470.1915300.192112

0.1926940.1932760,1938590.1944410.195023

- 0.1956070.1961920,1967770.1973590.197944

0.1985290.1991i40.1996990.2002870.200872

0.2014590.2020440.2026310.2032180.203806

0.2043930.2049820.2055710.2061590.206748

0.2073360.2079270.2085170.2091080.209697

0.2102880.2108790.2114700.2120610,212653

0,2132450.2138380.2144310.2150230.215616

AgeNumber

of years

35103520353035403550

35603570358035903600

36103620363036403650

36603670368036903700

37103720373037403750

37603770378037903800

38103820383038403850

38603870388038903900

3910

Error ±

173,0173.5174.0174.5175.0

175.5176.0176.5177.0177.5

178.0178.5178.9179,4179.9

180.4180.9181.418X9182.4

182.9183.4183.9184,4184.9

185,4185.8186.3186,8187.3

187.8188,3188.8189.3189.8

190.3190.819X3191.8192.3

192.73920 193.23930 193.73940 194.23950 194,7

3960 195,23970 195.73980 196,23990 196.74000 197.2

Page 45: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

38 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

4010-4500

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

N 206/N 238

Age

Ratio Numfber Errorof +

years

0.85206? 4010 8.9 0.8549i5 4020 8.9 0.857765 4030 8,9 0.860626 4040 9.0 0.863486 4050 9.00.866352 4060 9.0 0.869224 4070 9.0 0.872099 4080 9.0 0.874978 4090 9.1 0.877861 4100 9.10.880750 4110 9.1 0.883644 4120 9.1 0.886540 4130 9.2 0.889443 4140 9.2 0.892347 4150 9.20.895257 4160 9.2 0.898172 4170 9.2 0.901092 4180 9.3 0.9040i7 4190 9.3 0.906946 4200 9.30.909879 4210 9.3 0.9128i7 4220 9.4 0.915759 4230 9.4 0.918705 4240 9.4 0.921655 4250 9.40.9246i3 4260 9.4 0.927571 4270 9.5 0.930537 4280 9.5 0,933506 4290 9.5 0.936480 4300 9.50,939459 4310 9.6 0.942441 4320 9.6 0.945430 4330 9.6 0.948422 4340 9.6 0.951420 4350 9.60.9544i9 4360 9.7 0.957428 4370 9.7 0.960438 4380 9.7 0.963453 4390 9.7 0.966472 4400 9.80.969496 4410 9.8 0.972527 4420 9.8 0.9755&2 4430 9.8 0.978598 4440 9.8 0.981642 4450 9.90.984690 4460 9.9 0.987743 4470 9.9 0.9908oo 4480 9.9 0.993862 4490 10.0 0.996930 4500 10.0

^207/^35

AgeD,, Number Ratio Error

of +years

48.32153 4010 90.0 48.80331 4020 90.2 49.28987 4030 90.4 49.781i2 4040 90.7 50.27722 4050 90.950.778i7 4060 9U 5X28396 4070 9X3 51.79474 4080 9X6 52.31046 4090 9X8 52.83127 4100 92.053.357i7 4110 92.2 53,888i6 4120 92.5 54.42438 4130 92.7 54.96579 4140 92.9 55.51254 4150 93,156.06464 4160 93.4 56.62207 4170 93.6 57.185oi 4180 93.8 57.75338 4190 94.0 58.32736 4200 94.258,90696 4210 94.5 59.492i5 4220 94.7 60,083i2 4230 94.9 60.67980 4240 95.1 6X28238 4250 95.461.89085 4260 95.6 62.505i9 4270 95.8 63.12560 4280 96.0 63.752oi 4290 96.3 64.38459 4300 96,565.02336 4310 96.7 65.66830 4320 96.9 66.319&2 4330 97.2 66.97722 4340 97.4 67.64132 4350 97.668.31191 4360 97.8 68.98897 4370 98.1 69.67272 4380 98.3 70.36308 4390 98.5 7X06025 4400 98.77X76425 4410 99.0 72.47503 4420 99.2 73.19284 4430 99,4 73.91758 4440 99.6 74.64949 4450 99.975.38854 4460 100.1 76.13473 4470 100.3 76.88829 4480 100.5 77.649i4 4490 100.8 78.41750 4500 10X0

N 207/N206

AgeD . Number ~ Ratio . . Error

°f + years ~*

0,411844 4010 135> 0.414564 4020 135.6 0.417306 4030 135.8 0.420064 4040 136.0 0.422845 4050 136.20.425646 4060 136,5 0.428465 4070 136,7 0,431306 4080 136.9 0,434167 4090 137.2 0.437050 4100 137.40.439952 4110 137.6 0.442875 4120 137.8 0.445821 4130 138.1 0.448787 4140 138.3 0.451776 4150 138.5

0.454786 4160 138.7 0.457817 4170 139.0 0.460870 4180 139.2 0.463945 4190 139.4 0.467043 4200 139.60.470163 4210 139.9 0.473306 4220 140.1 0.476472 4230 140.3 0.479660 4240 140.6 0.482873 4250 140.80.486107 4260 14X0 0.489367 4270 14X2 0.492649 4280 141.5 0.495955 4290 14X7 0.499286 4300 14X90.502640 4310 142.2 0.506020 4320 142,4 0.509423 4330 142.6 0.512851 4340 142.8 0.516304 4350 143.10.519784 4360 143.3 0.523286 4370 143,5 0.5268i6 4380 143.8 0.530371 4390 144.0 0.533953 4400 144.20.537561 4410 144.4 0.541193 4420 144.7 0.544853 4430 144.9 0.548541 4440 145.1 0.552255 4450 14^40.555996 4460 145.6 0.559763 4470 145.8 0.563560 4480 146.0 0.567383 4490 146.3 0.571234 4500 146.5

N2 08/N2 3 2

AgeD Number Ratio Error

of +yearr

0,2162io 4010 197.7 0.216803 4020 198.2 0.217397 4030 198.7 0.217994 4040 199.2 0.218587 4050 199.60.219183 4060 200.1 0.219776 4070 200.6 0.220372 4080 20X1 0.220969 4090 201.6 0.221563 4100 202.1

0.222160 4110 202.6 0.222758 4120 203.1 0.223355 4130 203.6 0.223952 4140 204.1 0.224550 4150 204.60.225147 4160 205.1 0,225745 4170 205^6 0.226343 4180 206,1 0.226942 4190 206,5 0.227542 4200 207.00.228142 4210 207.5 0.228741 4220 208.0 0.229341 4230 208.5 0.229941 4240 209.0 0,230542 4250 209.50.231142 4260 210.0 0,231745 4270 210.5 0.232345 4280 211.0 0.232948 4290 21X5 0.233549 4300 212,00.234150 4310 212.5 0,234753 4320 213.0 0.235356 4330 213.5 0.235960 4340 213.9 0.236563 4350 214.40.2371&7 4360 214.9 0.237771 4370 215,4 0.238375 4380 215.9 0.238980 4390 216.4 0.239584 4400 216.90,240190 4410 217.4 0.240796 4420 217.9 0.241402 4430 218,4 0,2420o7 4440 218.9 0.2426i4 4450 219.40.243221 4460 219.9 0.243828 4470 220.4 0.244435 4480 220.8 0.245044 4490 22X3 0.245651 4500 22X8

Page 46: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

TABLES FOR THE CALCULATION OF LEAD ISOTOPE AGES

4515-5250

39

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

N 206/N 238

Age

Ratio Nufer Errorof +

years

1.001538 4515 10,0 1006158 4530 10.0 1.010789 4545 10.1 1.015429 4560 10.1 1020080 4575 10.11024745 4590 10.2 1029416 4605 10.2 I0341oo 4620 10.2 1038795 4635 10.3 1043499 4650 10.31048218 4665 10.3 1052944 4680 10.4 1057683 4695 10.4 1062431 4710 10.4 1067192 4725 10.51.071963 4740 10.5 1,076746 4755 10.5 1081538 4770 10,6 1086344 4785 10.6 1091157 4800 10.61095986 4815 10.7 1100823 4830 10.7 1105671 4845 10.7 1110532 4860 10.8 1115402 4875 10.81120283 4890 10.8 1125177 4905 10.9 1130084 4920 10.9 l,1350oi 4935 10.9 1139928 4950 1101.144866 4965 HO 1149817 4980 11.0 1154777 4995 HI 1159751 5010 111 1164737 5025 11.11169733 5040 11.2 1174743 5055 112 1179759 5070 11.2 1184791 5085 113 1189836 5100 1131.194887 5115 11,3 1199953 5130 114 1.205033 5145 114 1210122 5160 114 1215222 5175 1151.220333 5190 115 1225459 5205 H5 1230598 5220 116 1.235744 5235 116 1240905 5250 11.6

^207/^35

AeeD Number Ratio Error

° f ± years

79.5840 4515 1013 80.7678 4530 1017 819688 4545 102.0 83.1876 4560 102.3 84,4243 4575 102.785.6790 4590 103.0 86.9524 4605 103.3 88.2443 4620 103.7 89.5553 4635 104.0 90.8854 4650 104.392.2351 4665 104.7 93.6047 4680 105.0 94.9943 4695 105.4 96.40 4 5 4710 105.7 97.8352 4725 106.099,2870 4740 106.4

100.7602 4755 106.7 102,2550 4770 107.0 I03.77i8 4785 107.4 105,3107 4800 107.7106.8723 4815 108.1 108.4569 4830 108.4 110.0647 4845 108.7 1116963 4860 109.1 113.35i6 4875 109.4115.03i4 4890 109.7 116.7358 4905 110.1 118.4652 4920 110.4 120.22o2 4935 110.7 122.0007 4950 1111123.80 7 5 4965 1114 125.6409 4980 1118 127.50ii 4995 112.1 129.3888 5010 112.4 13130 4 o 5025 112.8133.2474 5040 113,1 135.2195 5055 113.4 137,22o4 5070 113.8 139.2508 5085 114,1 14131io 5100 114.4143.40i3 5115 114.8 145.5226 5130 115.1 147.6748 5145 115.5 149.8588 5160 115.8 152.0748 5175 116.1154.3233 5190 116.5 156.6049 5205 116.8 158.92oo 5220 117.1 1612692 5235 117.5 163.6527 5250 117,8

W 207/W 206

Agen . Number ^ Ratio . Error

°f + years ~

0.577064 4515 146.9 0.582959 4530 147,2 0.5889i7 4545 147,5 0.594943 4560 147.9 0.601034 4575 148,20.607190 4590 148.6 0.6134i8 4605 148,9 0.619712 4620 149.3 0.626076 4635 149.6 0,6325ii 4650 150,00.6390i4 4665 150.3 0,645592 4680 150.7 0,652241 4695 1510 0.6589&5 4710 1513 0.6657&2 4725 15170,672634 4740 152.0 0.679582 4755 152.4 0.686608 4770 152.7 0.6937io 4785 153,1 0.700892 4800 153.40.708152 4815 153.8 0.715494 4830 154.1 0,7229i7 4845 154.5 0.730422 4860 154.8 0.7380io 4875 155.20,745683 4890 155.5 0,753441 4905 155.9 0.761283 4920 156,2 0.7692i4 4935 156.6 0.777233 4950 156,90.785341 4965 157.3 0.793539 4980 157.6 0.801829 4995 158.0 0,8l02io 5010 158.3 0,818684 5025 158.70.827252 5040 159.0 0.8359i5 5055 159.4 0.844678 5070 159.7 0,853536 5085 160.1 0.862491 5100 160,40,871550 5115 160,8 0,880708 5130 1611 0.889966 5145 1615 0,899330 5160 1618 0.908798 5175 162.20.918373 5190 162.5 0.928053 5205 162.9 0.937839 5220 163.2 0.947739 5235 163.6 0.957747 5250 163.9

N208/N232

AgeD Number ^ Ratio Error

of +years

0,246564 4515 222.6 0,247475 4530 223.3 0,248389 4545 224.0 0,249304 4560 224.8 0.250220 4575 225.50.251134 4590 226,3 0.252051 4605 227.0 0.2529&7 4620 227.7 0,253887 4635 228.5 0,254805 4650 229.20,255723 4665 230,0 0,256643 4680 230.7 0.257564 4695 2314 0.258486 4710 232.2 0,259407 4725 232.90.260330 4740 233.7 0,261252 4755 234,4 0,262175 4770 235.1 0.2631oo 4785 235.9 0.264026 4800 236,60.264951 4815 237.4 0.265879 4830 238,1 0.266806 4845 238.8 0.267734 4860 239.6 0.268662 4875 240.30.269592 4890 2411 0,270521 4905 2418 0.271451 4920 242.5 0.272383 4935 243.3 0.273316 4950 244.00.274247 4965 244.8 0,275182 4980 245.5 0.276115 4995 246.2 0.277050 5010 247.0 0,277985 5025 247.70,278921 5040 248.5 0.279858 5055 249.2 0,280795 5070 249.9 0,281734 5085 250.7 0,282673 5100 25140.283613 5115 252.1 0.284553 5130 252.9 0.285493 5145 253.6 0.286436 5160 254.4 0.287377 5175 255.10.288319 5190 255.8 0.289263 5205 256^6 0,2902 07 5220 257.3 0.291154 5235 258.1 0.2921oo 5250 258.8

Page 47: Shorter Contributions to General Geology 1958 · 2011-05-25 · SHORTER CONTRIBUTIONS TO GENERAL GEOLOG GEOLOGICAL SURVEY PROFESSIONAL PAPER 334-A Tables for the calculation of geologic

40 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

5265-6000

Geologic age, in millions of years, calculated from the atomic ratios of indicated isotopes

^206/^238

Age

Ratio Error of +

years

3,246076 5265 11,71.2512s 9 5280 11.71,2564s? 5295 1171.261664 5310 11.83,266883 5325 1X8X2721i6 5340 1X8X277361 5355 1X9X282616 5370 1X91.287885 5385 1X91.293166 5400 12.0X298458 5415 12.03,303764 5430 12.0X309080 5445 12.1X3144ii 5460 12.11,319752 5475 12.1X325105 5490 12.21.330471 5505 12,2X335850 5520 12.21.3412 4 3 5535 12.31.346645 5550 12.3

X352062 5565 12.31.357491 5580 12.4X362931 5595 12.41.368385 5610 12,43,373851 5625 12.51.379330 5640 12.5X384823 5655 12.51,390327 5670 12.6X395843 5685 1261.401373 5700 12.6X4069i5 5715 12.7X412469 5730 12,7X418041 5745 12,7X423620 5760 12.81,429214 5775 12.81,434819 5790 12.8X440439 5805 12.91.446073 5820 12.91.451718 5835 12.9X457377 5850 13.01.463050 5865 13.01.468733 5880 13,01.474434 5895 13,11.480143 5910 13.11.485867 5925 13.1X491604 5940 13.2X497355 5955 13.2X503120 5970 13.2X508897 5985 13.3X514686 6000 13.3

"2077*235

AgeD Number Ratio Error

of 4.years

166.0713 5265 118,1168.5255 5280 118.517X0157 5295 118.8173,5424 5310 119.2176.1064 5325 119.5178.7079 5340 119.8181.3477 5355 120.2184.0262 5370 120,5186.7440 5385 120,8189.5020 5400 12X2192.30o2 5415 12X5195.1398 5430 12X9198.02o8 5445 122.2200.9442 5460 122.5203.9108 5475 122.9206.9207 5490 123.2209.9750 5505 123,5213.0740 5520 123.9216.2185 5535 124,2219.40 94 5550 124.5222.6469 5565 124.9225.9323 5580 125.2229.2657 5595 125,6232.6480 5610 125.9236.0802 5625 126,2239.5627 5640 126.6243.09&5 5655 126.9246.6820 5670 127.2250.32o2 5685 127,6254.0120 5700 127.9257.7578 5715 128.226X5590 5730 128.6265.4157 5745 128.9269.3290 5760 129.3273.30oi 5775 129.6277.3292 5790 129.9281.4179 5805 130.3285.5662 5820 130.6289.7756 5835 130.9294.0470 5850 13X3298.3809 5865 13X6302.7788 5880 13X9307,24o9 5895 132.331X7686 5910 132.6316.3631 5925 133.0321.0249 5940 133.3325.7554 5955 133.6330.5550 5970 134.0335.4252 5985 134,3340.3672 6000 134.6

N 207/N 206

Age Number ,-, Ratio . Error

of +years

0,967868 5265 164.30.978103 5280 164,60,988449 5295 165.00,9989i3 5310 165.3X009496 5325 165.71.020194 5340 166.0X0310i4 5355 166.4X041955 5370 166.7I,0530i8 5385 167.1X064205 5400 167.41.075518 5415 167.8X086958 5430 168.1X098527 5445 168.51.110223 5460 168.93,122054 5475 169.2X1340i7 5490 169.63,1463.15 5505 169.91.158347 5520 170.3X170715 5535 170.6X183227 5550 17X0

X195876 5565 17X31.208669 5580 17X7X221606 5595 172.01.234687 5610 172.4X2479i8 5625 172.7X261296 5640 173,1X274825 5655 173.5X288506 5670 173.8X302343 5685 174.2X316335 5700 174,5X330485 5715 174.9X344797 5730 175^2X359264 5745 175.6X3739oo 5760 175.9X3887oo 5775 176,3X403668 5790 176.7X418805 5805 177.0X4341ii 5820 177.41.449591 5835 177,7X465247 5850 178.1X481078 5865 178.4X497092 5880 178.8X513282 5895 179.1X529659 5910 179.51.546222 5925 179.9X562972 5940 180.2X5799i2 5955 180.6X5970 4 i 5970 180.9X614366 5985 18X3X631891 6000 18X6

N208/N232

AgeD . Number _ Ratio Error

of +years

0.293046 5265 259.50,293992 5280 260.30,294939 5295 26X00.295890 5310 261,80.296838 5325 262,50.297788 5340 263.20.298738 5355 264.00.299689 5370 264.70.300642 5385 265.50.301595 5400 266.2

0.302547 5^15 266.90.303501 5^30 267,70.304456 5445 268.40.305413 5460 269.20.306369 5475 269.90.307324 5490 270.60.308282 5505 271,40.309240 5520 272.10.310201 5535 272.90.311160 5550 273,6

0.312119 5565 274.30.313080 5580 275.10.314042 5595 275.80.315005 5*10 276.50.315968 5*25 277.30.316932 5*40 278.00.317896 5*55 278.80.318862 5*70 279,50.319829 5685 280.20.320794 5700 28X00.321763 5715 28X70.322730 5730 282.50.323699 5745 283.20.324669 5760 283.90.325639 5775 284,70.326609 5790 285.40.327581 5805 286.20.328554 5820 286,90,329528 5835 287.60.3305oo 5850 288.4

0.331474 5865 289.10.332450 5880 289.90.333427 5895 290.60.334404 5910 29X30.335381 5925 292.10.336359 5940 292,80.337338 5955 293,60.338317 5970 294.30.339298 5985 295.00.340279 6000 295,8

U. S. GOVERNMENT PRINTING OFFICE: 1959 O 485342