A Normative-Calculation Procedure Used 

to Determine Mineral Abundances in 

Rocks from the Montpelier Canyon Section 

of the Phosphoria Formation, Idaho: 

A Tool in Deciphering the Minor-Element 

Geochemistry of Sedimentary Rocks

U.S. GEOLOGICAL SURVEY BULLETIN 2023-A
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Chapter A

A Normative-Calculation Procedure Used 

to Determine Mineral Abundances in 

Rocks from the Montpelier Canyon Section 

of the Phosphoria Formation, Idaho: 

A Tool in Deciphering the Minor-Element 

Geochemistry of Sedimentary Rocks

By M.D. MEDRANO and D.Z. PIPER

U.S. GEOLOGICAL SURVEY BULLETIN 2023

THE PHOSPHORIA FORMATION:

ITS CEOCHEMICAL AND BIOLOGICAL ENVIRONMENT OF DEPOSITION
U.S. DEPARTMENT OF THE INTERIOR 

MANUEL LUJAN, JR., Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

Any use of trade, product, or firm names

in this publication is for descriptive purposes only

and does not imply endorsement by the U.S. Government

Text and illustrations edited by George A. Havach

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1992

Free on application to 

Book and Open-File Report Sales 

U.S. Geological Survey 

Federal Center, Box 25286 

Denver, CO 80225

Library of Congress Cataloging in Publication Data

Medrano, M.D.

A normative-calculation procedure used to determine mineral abundances in 

rocks from the Montpelier Canyon section of the Phosphoria Formation, Idaho: 

a tool in deciphering the minor-element geochemistry of sedimentary rocks / 

by M.D. Medrano and D.Z. Piper.

p. cm. (U.S. Geological Survey bulletin ; 2023) (The Phosphoria 

Formation its geochemical and biological environment of deposition ; ch. A)

Includes bibliographical references.

1. Rocks, Sedimentary Idaho Montpelier Canyon Analysis. 

2. Mineralogy Idaho Montpelier Canyon. 3. Geochemistry Idaho 

Montpelier Canyon. 4. Phosphoria Formation. I. Piper, David Z. II. Title. 

III. Series. IV. Series: The Phosphoria Formation its geochemical and 

biological environment of deposition ; ch. A. 

QE75.B9 no. 2023-A 

[QE471] 

557.3 s dc20

[549.9796] 92-14791

CIP
CONTENTS

Abstract Al 

Introduction Al 

Analytical techniques A2 

Normative calculations A2

Mineral components A2

Mineral compositions A5

Apatite A5

Calcite and dolomite A6

Organic matter A6

Detritus A6

Biogenic silica A6

Discussion A7

Correlation-coefficient matrix A7 

Conclusion A7 

References cited A8

FIGURES

1. Sketch map of southeastern Idaho, showing locations of outcrops of the Phosphoria 

Formation and of samples from Montpelier Canyon A3

2. Stratigraphic column of the Phosphoria Formation in Montpelier Canyon A4

3. Plots comparing A12O3 , P2O5 , Fe2O3, and CaO contents measured by different

analytical techniques All 

4-7. Plots of:

4. TiO2 , Fe2O3 , and K2O versus A12O3 content, as determined by inductively coupled 

plasma atomic-emission spectroscopy A12

5. MgO and CaO versus inorganic-carbon content, and calculated versus measured 

carbonate content A13

6. CaO versus P2O5 content in apatite, as determined by inductively coupled plasma 

atomic-emission spectroscopy A13

7. Residual fraction versus A12O3 content, calculated versus measured SiO2 content, 

calculated SiO2 content versus A12O3 content measured by inductively coupled 

plasma atomic-emission spectroscopy, and calculated versus measured loss on 

ignition A14 

8. Bar graph showing calculated abundances of apatite, calcite, dolomite, organic

matter, detritus, and biogenic/diagenetic silica in each sample analyzed A15

TABLES

1. Major-element-oxide contents in samples of the Phosphoria Formation in Montpelier 

Canyon, Idaho A16

2. Minor-element contents in samples of the Phosphoria Formation in Montpelier 

Canyon, Idaho A18

3. Shale compositions A20

4. Formulas used in normative calculations A21

5. Mineral abundances in samples of the Phosphoria Formation in Montpelier Canyon, 

Idaho A22

6. Correlation coefficients for rock components and minor elements A23

III

A Normative-Calculation Procedure Used to Determine 

Mineral Abundances in Rocks from the Montpelier 

Canyon Section of the Phosphoria Formation, Idaho: 

A Tool in Deciphering the Minor-Element Geochemistry 

of Sedimentary Rocks

ByM.D. Medrano and D.Z. Piper

Abstract

We have analyzed samples of the Phosphoria Formation 

in Montpelier Canyon, Idaho, for major and minor elements. 

A normative calculation, using major-element-oxide ratios, 

was performed to quantify the rock components. Calcite, dolomite, apatite, biogenic/diagenetic silica, and organic matter 

represent the marine component, whereas the detrital fraction represents the nonmarine component. The CaO/P2O5 ratio in apatites is 1.38, and the organic-matter/organic-carbon 

ratio in the rocks is 1.7. In the detrital fraction, the SiO2/ 

AI2O3 ratio is 3.8, the Fe2O3/AI2O3 ratio is 0.31, the MgO/ 

AI2O3 ratio is 0.15, the CaO/AI2O3 ratio is 0.26, the K2O/ 

AI2O3 ratio is 0.26, the TiO2/AI2O3 ratio is 0.03, and the 

P2O5/AI2O3 ratio is 0.01. A simple correlation of major rock 

components with minor elements shows that most of the minor elements are strongly associated with either organic matter or the detrital fraction, or both.

INTRODUCTION

The Phosphoria Formation, which was deposited on a 

Permian continental shelf (the then-west edge of the North 

American Continent) extending over four Western States, 

was studied extensively by U.S. Geological Survey geologists (see McKelvey and others, 1953a, and references 

therein) from the 1950's through the 1970's. It was 

mapped extensively, and its stratigraphy was determined. 

Major-element-oxide contents were determined by wet 

chemical analysis, and mineralogy by optical microscopy 

and X-ray-diffraction (XRD) spectroscopy. Minor elements, however, were not extensively examined in these 

early studies. The improved resolution of today's analytical techniques with respect to minor elements may further

Manuscript approved for publication, January 31, 1992.

contribute to our understanding of the geochemical environment within which this formation was deposited. For 

this purpose, we use a normative-calculation procedure.

This report presents a step-by-step explanation of a 

normative-calculation procedure that does not follow the 

Cross, Iddings, Pirsson, and Washington (CIPW) normative scheme used in igneous petrology, whereby the minerals calculated are fictitious and used only for comparison 

and classification purposes. Instead, we determine from 

major-element-oxide ratios in sedimentary-rock-forming 

components or phases the actual abundance of each mineral in each sample. Leinen (1977), Isaacs (1980), and 

Isaacs and others (1983) pioneered this approach in sedimentary processes. For example, Leinen developed a normative-calculation technique to determine the opal content 

of deep-sea sediment. First, she derived an equation for 

calculating the nonbiogenic-silica abundance, using linear 

regression analysis; this value was then subtracted from 

the total silica content to give the opal abundance. Isaacs 

(1980), in her exhaustive study of the Monterey Formation, determined the abundance of calcite, the SiO2 content 

of aluminosilicates, and the aluminosilicate fraction directly from major-element-oxide analyses, using proportionality constants. The abundances of biogenic silica and 

detrital quartz were determined by peak intensities on 

XRD traces. Later, Isaacs and others (1983) derived proportionality constants for detrital quartz, dolomite, and apatite. Both Leinen (1977) and Isaacs and others (1983) 

used other methods as checks on their calculations, supporting the validity of this technique.

The purpose of our procedure is twofold. First, by determining quantitatively the mineral abundances in each 

rock sample, we can differentiate between the proportion 

of the rock that is of terrigenous origin and that which is of 

marine origin. Assuming that we can assign a fraction of 

the minor-element content to the terrigenous component,

Mineral Abundances in Rocks from the Montpelier Section of the Phosphoria Formation, Idaho A1
we can calculate the marine component of the minor elements, which can then be compared with the marine mineral abundances. These comparisons allow us to distinguish 

between initial multiple marine sources and current host 

mineral phases for minor elements: Initial sources relate to 

the aqueous and organic chemistry of the depositional environment, and current phases to the pore-water and crystalline chemistry of early diagenesis (Piper, 1991).

Second, by determining quantitatively the mineral 

abundances and their stoichiometries for several sections 

of the Phosphoria Formation, we can look for possible 

chemical variations across the basin. For example, the terrigenous component most likely varies across the basin as 

a function of the distance from source, whereas the marine 

component may vary owing to both areal and depth-related variations in seawater chemistry.

ANALYTICAL TECHNIQUES

Laboratory-prepared powders of samples, which were 

collected by McKelvey and others (1953b), were analyzed 

for major-element oxides and minor elements (table 1). 

The samples are from the section of the Phosphoria Formation exposed in Montpelier Canyon, southeastern Idaho 

(fig. 1). Most samples are from the Meade Peak Phosphatic Shale Member (fig. 2), three are from the upper shale 

member (equivalent to either the cherty shale member or 

the Retort Phosphatic Shale Member; see McKelvey and 

others, 1959), and one is from the Rex Chert Member 

(McKelvey and others, 1959; see McKelvey and others, 

1953a, for sample descriptions).

Major-element oxides (except SiO2) in 45 samples 

were measured by inductively coupled plasma (ICP) atomic-emission spectroscopy after acid digestion (Lichte and 

others, 1987). Precision, based on multiple analyses of 

U.S. Geological Survey standard reference materials, is 

±10 percent for concentrations greater than 10 times the 

lower limit of detection. Limits of detection, in weight 

percent, are as follows: A12O3 (0.09), CaO (0.07), Fe2O3 

(0.07), K2O (0.1), MgO (0.08), NajO (0.1), P2O5 (0.02), 

and TiO2 (0.02).

Major-element oxides (including SiO2) in aliquots 

from 21 samples were measured by wavelength-dispersive 

X-ray-fluorescence (XRF) spectroscopy (Taggart and others, 1987) and loss on ignition (LOI). Samples were fused 

with lithium tetraborate, the melts cast into polished point 

molds, and the resulting glass disks weighed and then analyzed. Precision is better than ±5 percent and, depending 

on the element, as low as ±0.2 percent. ICP and XRF 

analyses, along with several wet chemical analyses originally reported by McKelvey and others (1953b), are listed 

in table 1.

Comparisons of the XRF, wet chemical, and ICP data 

(fig. 3) show only slight differences between the three

methods for major-element oxides. The ICP data for A12O3 

are about 4 percent higher, on average, than the XRF data 

(fig. 3A); the ICP data for P2O5 are virtually the same as 

both the XRF and wet chemical data (fig. 3B); the ICP 

data for Fe2O3 are as much as 9 percent lower than the 

XRF and wet chemical data (fig. 3C); and the ICP data for 

CaO are about 2.5 percent lower than the XRF data (fig. 

3D). These plots confirm the accuracy and precision of the 

XRF and ICP analyses reported by Lichte and others 

(1987) and Taggart and others (1987), with the possible 

exception of Fe2O3 .

Minor elements in all samples were determined by 

ICP spectroscopy (table 2), including the following (limit 

of detection in parts per million in parentheses): Ag (2), 

As (10), Au (8), Ba (1), Be (1), Bi (10), Cd (2), Ce (4), Co 

(1), Cr (1), Cu (1), Eu (2), Ga (4), Ho (4), La (2), Li (2), 

Mn (10), Mo (2), Nd (4), Ni (2), Pb (4), Sc (2), Sn (10), 

Sr (2), Ta (40), Th (4), U (100), V (2), Y (2), Yb (1), and 

Zn (2). Precision, based on multiple analyses of U.S. Geological Survey standard reference materials, is ±10 percent 

for concentrations greater than 10 times the lower limit of 

detection, (Lichte and others, 1987). The 20 elements listed in table 2 are those for which at least half the measurements were above the limit of detection. A zero was 

substituted for those analyses below the limit of detection 

to facilitate calculations.

Inorganic and total carbon were determined by combustion (table 1); the difference gives the fraction of organic carbon. Precision is from 5 to 10 percent, based on 

an analysis of aliquots to which CaCO3 was added in an 

amount that approximately doubled the original carbon 

content.

NORMATIVE CALCULATIONS 

Mineral Components

The major-element oxides must be partitioned into 

mineral phases to determine the mineral abundances in the 

rock samples. In the Phosphoria Formation, Gulbrandsen 

(1967) identified quartz, muscovite-illite, feldspar, iron oxide, organic matter, and apatite as ubiquitous phases and 

calcite, dolomite, microcrystalline quartz, and gypsum as 

present only in some of the rocks. Plots of major-element 

oxides and inorganic and organic carbon confirm that apatite, calcite, dolomite, organic matter, and biogenic/diagenetic silica (microcrystalline quartz) are major minerals in 

the Montpelier Canyon section. The plot of Fe2O3 versus 

A12O3 content (fig. 4B) also indicates that a few samples 

contain iron in excess of that contributed by aluminosilicates. Because at most 2 weight percent Fe (present now 

as an oxide but possibly pyrite originally) is present, its 

abundance was not calculated. Because the plot of SiO2 

versus A12O3 content (see fig. 1C) shows a strongly

A2 The Phosphoria Formation: Its Geochemical and Biological Environment of Deposition
113° 112s 111°

440-

43«

\

\

42° i

Outcrop of Phosphoria Formation 

dotted when questionable

<>1207 

Location and lot number of sample

0 20 Kilometers

IDAHO 

UTAH

Figure 1. Sketch map of southeastern Idaho, showing locations of outcrops of the Phosphoria Formation and of samples from Montpelier Canyon. After McKelvey and others (1953a).

Mineral Abundances in Rocks from the Montpelier Section of the Phosphoria Formation, Idaho A3
EXPLANATION Dinwoody Fm. 

1.2mPhosphate , Q 4 

rock

Argillaceous 

limestone

Phosphatic 

chert

Calcareous 

mudstone

Calcareous 

chert

Cherty 

limestone

Argillaceous

phosphate

rock

Phosphatic 

mudstone

Calcareous 

phosphate

Quartzite

"Interbedded" 

limestone and chert

T

5

I

5 METERS

 i i LI LI

rU-12

R-22

3C-3C-3C-3E-3 

C-3C-3C-3C-3C3C-3C-3C-3I-3 

C-3C-Jt-]C-]t3C-3C-JC-3C-3

43.2m

52m

86.2 m-

-P-168

-P-165 

P-163

»~

rfr«ri

 g^-w

P-157

;|J: 131 104.9m-

 P-105

 P-104

 P-103

 P-100

-- --- - P-87

J- P-82

128.7 m

r_-±_-_ - P-52

Figure 2. Stratigraphic column of the Phosphoria Formation in Montpelier Canyon, showing locations of samples analyzed. 

Compiled from McKelvey and others (1953a).

A4 The Phosphoria Formation: Its Geochemical and Biological Environment of Deposition
defined minimum and Fe2O3, K2O, and TiO2 (fig. 4) correlate strongly with A12O3 but not with any other major-element oxide, Gulbrandsen's quartz, muscovite-illite, and 

feldspar phases (quartz and aluminosilicates) were combined into a single detrital fraction, assumed to have a 

constant A12O3 content. Isaacs (1980) and Isaacs and others (1983) also chose to combine all the aluminosilicates 

and detrital quartz into a single detrital fraction. They determined independently the abundances of the mineral 

phases that compose this fraction, including detrital quartz, 

and concluded that the relative proportions of the mineral 

phases of the detrital fraction in fine-grained rocks vary 

only slightly, owing to the absence of mineral fractionation as the detrital material was transported to and deposited in a marine basin.

Following the format of Isaacs (1980) and Isaacs 

and others (1983), we assign the major-element-oxide 

contents, not accommodated in the detrital fraction, to biogenic/diagenetic silica, apatite, dolomite, calcite, and organic matter, by assuming a constant composition for 

each. The rocks may be sufficiently complex that our 

simple assumptions used to calculate their components 

are invalid. For example, we use the MgO content, in 

excess of that accommodated in the detrital fraction, to 

calculate dolomite. Similarly, we use the P2O5 content to 

calculate the apatite content. If these rocks contained other mineral phases in which MgO and P2O5 were present, 

these calculations would be far more complex and much 

less accurate.

Mineral Compositions

Our initial assumption is that each mineral component 

has a constant composition throughout the stratigraphic 

column. Implicit in this assumption is that all the samples 

are closely associated. The plots of major-element oxides 

and organic and inorganic carbon strongly support the assumption that the minerals have constant major-elementoxide ratios.

The number and approximate composition of the major components must be known to partition the major-element oxides. For calcite and dolomite, partitioning of 

CaO, MgO, and CO2 is relatively straight forward: We assume stoichiometric phases. As shown below, extremums 

in the plots of CaO and MgO versus inorganic-carbon 

content support this assumption. Apatite varies slightly 

from place to place in composition, owing to substitution 

of CO32- and SO42- for PO43- and of Na+ and Mg2+ for Ca2+ 

(McClellan, 1969). Gulbrandsen (1966), however, reported 

a limited variation in the composition of apatite in the 

Phosphoria Formation about an average that approaches 

our measurements. The composition of detritus can vary 

significantly from formation to formation, depending on 

such factors as source and degree of alteration. Initially,

we assumed that the detrital fraction was similar in composition to the average for worldwide shales (table 3). On 

the plots of major-element-oxide versus A12O3 content (fig. 

4), K2O, TiO2, and Fe2O3 all correlate well with A12O3 (fig. 

4). Least-square best-fit lines were drawn, yielding R values greater than 0.93. Assuming that A12O3 is present solely in the detrital fraction, it follows that K2O, TiO2, and 

Fe2O3 also must be present solely in the detrital fraction. 

Their high degree of correlation and extrapolation to the 

origins of these plots confirm our assumptions that (1) the 

composition of the detrital fraction is constant throughout 

the stratigraphic column in Montpelier Canyon, (2) the 

compositional values approximate those of the average for 

worldwide shales (table 3), and (3) the detrital fraction has 

remained relatively nonreactive since deposition. Subsequent studies are underway to ascertain whether these assumptions hold true for the entire basin.

Although the other major-element oxides used to determine mineral abundances (CaO, P2O5 , MgO) show no 

obvious correlation with A12O3, some of each oxide can be 

present in detritus, as well as in other components. In fact, 

the plot of MgO versus inorganic-carbon content (fig. 5A) 

requires that some MgO is present in both dolomite and 

detritus: The curve extrapolates to 0.7 weight percent 

MgO. The average MgO content of worldwide shales is 

2.6 weight percent (Wedepohl, 1969). Because the average 

proportion of detritus in these samples is 30 percent, the 

average detrital MgO content of worldwide shales is 0.78 

weight percent (0.30 times 2.6 weight percent). The close 

agreement of this value with the expected value of 0.78 

weight percent in Wedepohl's (1969) average for worldwide shales supports our use of his values to subtract out 

the detrital (shale) fraction (table 3) of the major-element 

oxides CaO, MgO, P2O5 before calculating the abundances of the mineral components calcite, dolomite, and 

apatite (tables 4, 5).

Apatite

The major-element-oxide stoichiometry of apatite, as 

determined by Gulbrandsen (1966) and McClellan and 

Lehr (1980), was evaluated by plotting CaO versus P2O5 

content (fig. 6). Minimums define a curve with a slope of 

1.38 that intercepts the origin, in agreement with the CaO/ 

P2O5 ratio reported by both Gulbrandsen (1966, 1970) and 

McClellan and Lehr (1969); the rest of the data plot above 

this curve. Clearly, CaO is present in other phases; however, because the extremums extrapolate to zero, we conclude that virtually all of the P2O5 is present in apatite, 

except for 0.16 weight percent P2O5 in detritus (Wedepohl, 

1969). Therefore, we use the P2O5 content to calculate the 

apatite abundance. The actual P2O5 content in apatite and 

the complete equation used to calculate the apatite abundance are listed in table 4.

Mineral Abundances in Rocks from the Montpelier Section of the Phosphoria Formation, Idaho A5
Calcite and Dolomite

MgO and CaO were plotted against inorganic carbon 

(fig. 55), after subtracting out their detrital and apatite 

contributions. The apatite fraction of CaO was determined 

as described above. The detrital fractions of CaO and 

MgO were estimated from the average for worldwide 

shales (table 3). The adjusted CaO data plot along the 

curve for stoichiometric calcite, or between the calcite and 

dolomite curves; the first relation suggests that the calcite 

in the Phosphoria Formation is stoichiometric CaCO3 .

MgO data plot either on the curve representing the ratio 

of MgO to inorganic carbon in stoichiometric dolomite or 

below it (fig. 55). MgO data that plot on this curve represent 

samples that contain only stoichiometric dolomite, and 

those that plot below this curve represent samples that contain both calcite and dolomite. MgO data plot along the xaxis, where there is only calcite. These plots support the 

assumption that MgO is present only in dolomite, except for 

2.3 weight percent in detritus (table 3), and that stoichiometric dolomite (table 4) is present in at least a few samples.

Organic Matter

Organic-matter content was determined by multiplying the organic-carbon content by 1.7. This value, which is 

intermediate between the organic-matter content of the 

Monterey Formation of 1.5 weight percent (Isaacs, 1980) 

and modern marine organic-matter content of approximately 4 weight percent (Sverdrup and others, 1963), was 

obtained by comparing the measured LOI with an "LOI 

term" obtained by an iterative calculation (see subsection 

below entitled "Biogenic Silica").

Detritus

A residual fraction was calculated by subtracting the 

proportion of calcite, dolomite, apatite, and organic matter 

from 100 percent. Thus, this residual fraction equals the 

sum of the detrital fraction and biogenic-silica abundance. 

The residual fraction was then plotted against A12O3 content; the plot shows a well-defined minimum that nearly 

extrapolates to the origin (fig. 1A). The slope of the curve is 

interpreted to represent the ratio of detritus to A12O3 . Extrapolation to 100 percent gives an A12O3 content in detritus 

of 15.6 weight percent. This value compares well (table 3) 

with the averages of 16.7 weight percent for geosynclinal 

shales (Wedepohl, 1969), of 15.1 weight percent for Russian platform shales (Vinogradov and Ronov, 1956), and of 

17.8 weight percent for the detrital fraction of the Monterey 

Formation (Isaacs, 1980). The scatter of the data points

above the curve represents a varying abundance of biogenic 

silica, which has no intrinsic relation to A12O3 .

Biogenic Silica

The abundance of biogenic/diagenetic silica can be 

calculated merely by assuming it to be the sole remaining 

major constituent, thus forcing the sum of all constituents 

to 100 percent. Because the abundance of calcite partly 

depends on the calculated abundance of dolomite and apatite, and the abundances of detritus and biogenic silica also 

depend on the calculated abundances of calcite, dolomite, 

apatite, and organic matter, the results would contain errors compounded by each successive calculation. An alternative method is to determine the SiO2 content of the 

detrital fraction and then subtract it from the total silica 

content. This calculation can be done by simply plotting 

total silica against A12O3 content; the minimums define a 

curve that is interpreted to be the SiO2/Al2O3 ratio in detritus (Isaacs, 1983). The scatter of data points above this 

curve represents silica in excess of that in the detritus, that 

is, biogenic/diagenetic silica. In this study, however, only 

the samples analyzed by XRF spectroscopy have a total 

silica content, and they represent only half the samples. 

Therefore, we developed an equation for calculating total 

silica content from the ICP data.

We initially use only the XRF data to derive the equation for total silica content because this procedure allows 

us to compare our calculated total silica content with the 

measured total silica content. Part of the equation is an 

LOI term, which we also derive by using the XRF data 

and again compare with the measured LOI data. We then 

apply both equations to the ICP data.

Total silica content was calculated by subtracting 

four terms from 100 weight percent: (1) a term incorporating all the major-element oxides other than SiO2, (2) a calculated LOI term, (3) a calculated fluorine term, and (4) a 

term for sulfur plus other significant minor elements (table 

4). The major-element-oxide contents used in the first term 

are listed in table 1. The LOI term is composed of an aluminosilicate factor (8-9 weight percent H2O in aluminosilicates), a carbonate factor (44 weight percent CO2 in 

calcite and 47 weight percent CO2 in dolomite), and an 

organic-matter factor (58.8 weight percent organic carbon). The equation is:

LOI=0.55Al2O3+3.66Inorganic Carbon 

+1.7Organic Carbon.

An iterative calculation designed to obtain the best-fit 

curve between the measured and calculated LOI gave a 

ratio of organic matter to organic carbon of 1.7 for these 

samples (fig. ID), in comparison with a ratio of 1.5 for the

A6 The Phosphoria Formation: Its Geochemical and Biological Environment of Deposition
Monterey Formation (Isaacs, 1980). The H2O content of 

detritus was determined as 8.6 weight percent.

Fluorine, for which we have no data, is present in apatite in significant amounts, 3.8 to 4.2 weight percent, as 

fluoride (Gulbrandsen, 1966). Assuming 4.2 weight percent 

F in apatite and reducing the number of oxygens to maintain charge balance, 2.47 percent of the apatite present was 

subtracted from 100 percent to account for fluorine.

After initially plotting calculated versus measured 

SiO2 content, another 1 weight percent was subtracted for 

maximum agreement with the measured value. This procedure was justified by the known presence of sulfur, as sulfate in apatite (0.3-3.1 weight percent SO3 ; Gulbrandsen, 

1966), and of significant amounts of minor elements, such 

as Cr, Sr, V, and Zn (table 2).

Assuming that other nonoxide components are absent, 

the remainder should then be equal to the total silica content. The calculated total silica content was plotted against 

the SiO2 content measured by XRF spectroscopy (fig. 7fi), 

with /?=0.99. The curve for minimums of calculated SiO2 

versus A12O3 content, with a slope of 3.75, defines the 

SiO2/Al2O3 ratio for the detrital fraction (fig. 7Q. The ratio for detritus may be less than this value, by the abundance of biogenic silica actually present in samples that 

define the minimum, or it may be higher than this value as 

a result of precision errors compounded with each oxide 

analysis. However, the sharpness of the minimum leads us 

to believe that the SiO2/Al2O3 ratio for detritus is close to 

3.75.

The abundance of biogenic silica was determined 

from the plot of total silica versus A12O3 content (fig. 1C). 

The amount by which the data points lie above the curve 

for silica in the detrital fraction represents the abundance 

of biogenic silica (see table 4 for actual equation used).

Discussion

All the calculated major mineral abundances are listed in table 5 and plotted in figure 8. By virtue of our normative-calculation procedure, 100 percent of the P2O5 , 

A12O3, CaO, and MgO are accounted for by this partitioning. The CO32", SiO2, and sum of components, however, 

each offers a check on the calculations. To check the calcite, dolomite, and apatite calculation, CO32~, calculated 

from the abundances of these mineral components (table 

5), is plotted against measured carbonate, that is, inorganic 

carbon (table 1): The correlation is excellent (fig. 5C). The 

SiO2 content was measured by XRF spectroscopy and estimated (fig. IB) from the contents of other major-element 

oxides plus an LOI calculation (table 4). Both plots show 

strong correlations that approach a 1:1 relation in the midrange. The approach of the sum of all components to 100

percent (fig. 8) also supports our partitioning scheme: For 

all but one of the samples, this sum is within ±3 percent 

of 100 percent. These results offer strong support for our 

initial assumption of a constant composition for all components.

In other rock units, oxide ratios in the major components may differ from those for the Phosphoria Formation, 

but this general scheme should be the same.

CORRELATION-COEFFICIENT MATRIX

A correlation-coefficient matrix indicates the degree 

of linear relation between two variables. The R value indicates how well the individual data points behave around a 

calculated simple regression (line). If the data points cluster close to the linear regression, then the R value approaches 1.0; and if there is no correlation, then the R 

value approaches zero. Negative correlations indicate an 

inverse relation and can be just as informative as positive 

correlations; however, low positive correlations must be 

viewed critically. For example, we know from plots and 

calculations that CaO is associated with MgO, inorganic 

carbon, and P2O5, although the correlation coefficients between CaO and these major-element oxides is significant 

(/?>0.5) only for CaO versus P2O5 (table 6). Therefore, we 

use the correlation-coefficient matrix as only an initial tool 

in evaluating the data.

Using a statistical program, a correlation-coefficient 

matrix was generated for all the data, that is, rock components and bulk minor-element analyses (table 6). Because 

the main purpose of this report is to explain our normative-calculation procedure, we mention only a few of the 

strongest correlations (table 6): detritus with Ba and Co, 

apatite with Sr, and organic matter with Cu and Cr. The 

rare-earth elements correlate very strongly with each other, 

as expected, because of their similar valence-electron configurations. Sc also correlates with the rare-earth elements. 

Mo, Ni, and Zn correlate strongly with each other but not 

with any of the calculated rock components. Eventually, 

we want to look similarly at data from four other places 

that traverse the Permian sea from east to west.

CONCLUSION

The abundances of the rock components were determined by assuming a constant composition throughout the 

stratigraphic column and assuming these components to be 

calcite, dolomite, apatite, organic matter, biogenic/diagenetic silica, and a single detrital fraction combining detrital quartz and aluminosilicates. Apatite abundance was 

calculated from P2O5 content, using 40.6 weight percent in

Mineral Abundances in Rocks from the Montpelier Section of the Phosphoria Formation, Idaho A7
apatite and 0.16 weight percent in detritus. Dolomite 

abundance was calculated by multiplying the analyzed 

MgO content, less that proportion in the detrital fraction, 

by the proportion of MgO in stoichiometric dolomite (21.9 

weight percent). CaO content was used to calculate calcite 

abundance (56 weight percent) after subtracting out its 

proportions in apatite, dolomite, and detritus. Organic-matter abundance was calculated by multiplying the organiccarbon content times 1.7, a factor derived from an iterative 

process. Biogenic/diagenetic-silica abundance was calculated by first calculating the total SiO2 content and then 

subtracting out the proportion in the detrital fraction. The 

validity of these calculations was checked by comparing 

the inorganic-carbon content calculated from the abundances of dolomite, calcite, and apatite with the measured 

inorganic-carbon content, by comparing the calculated 

with measured SiO2 content, and by the approach of the 

sum of the major rock components to 100 percent. This 

normative-calculation procedure can be applied in a general form to other fine-grained sedimentary rocks as well.

REFERENCES CITED

Balashov, Y.A., Ronov, A.B., Migdisov, A.A., and Turanskaya, 

N.V., 1964, The effect of climate and facies environment on 

the fractionation of the rare earths during sedimentation: Geochemistry International, v. 1, no. 5, p. 951-969.

Brumsack, H.J., 1986, The inorganic geochemistry of Cretaceous 

black shales (DSDP Leg 41) in comparison to modern upwelling sediments from the Gulf of California, in Summerhayes, C.P., and Shackleton, N.J., eds., North Atlantic 

palaeoceanography: Geological Society of London Special 

Publication 21, p. 44-62.

Gulbrandsen, R.A., 1966, Chemical composition of phosphorites 

of the Phosphoria Formation: Geochimica et Cosmochimica 

Acta, v. 30, no. 8, p. 769-778.

 1967, Some compositional features of phosphorites of the 

Phosphoria Formation, in Hale, L.A., ed., Anatomy of the 

western phosphate field: Intermountain Association of Geologists Annual Field Conference, 15th, Guidebook, p. 99- 

102. 

-1970, Relation of carbon dioxide content of apatite of the

Phosphoria Formation to regional facies, in Geological Survey research, 1970: U.S. Geological Survey Professional Paper 700-B, p. B9-B13.

Haskin, M.A., and Haskin, L.A., 1966, Rare earths in European 

shale; a redetermination: Science, v. 154, no. 3748, p. 507- 

509.

Heinrichs, Hartmut, Schulz-Dobrick, Burkhard, and Wedepohl, 

K.H., 1980, Terrestrial geochemistry of Cd, Bi, Tl, Zn and Rb: 

Geochimica et Cosmochimica Acta, v. 44, no. 10,1519-1533.

Isaacs, C.M., 1980, Diagenesis in the Monterey Formation examined laterally along the coast near Santa Barbara, California: 

Stanford, Calif., Stanford University, Ph.D. thesis, 329 p. 

[U.S. Geological Survey Open-File Report 80-606].

Isaacs, C.M., Keller, M.A., Gennai, V.A., Stewart, K.C., and Taggart, J.E., Jr., 1983, Preliminary evaluation of Miocene lithostratigraphy in the Point Conception COST well OCS-Cal 

78-164 No. 1, southern California, in Isaacs, C.M., and Garrison, R.E., eds., Petroleum generation occurrence in the Miocene Monterey Formation, California: Los Angeles, Society 

of Economic Paleontologists and Mineralogists, Pacific Section Special Publication 33, p. 99-110.

Leinen, Margaret, 1977, A normative calculation technique for 

determining opal in deep-sea sediments: Geochimica et Cosmochimica Acta, v. 41, no. 5, p. 671-676.

Lichte, F.E., Golightly, D.W., and Lamothe, P.J., 1987, Inductively coupled plasma-atomic emission spectrometry, chap. B of 

Baedecker, P.A., ed., Methods for geochemical analysis: U.S. 

Geological Survey Bulletin 1770, p. B1-B10.

McClellan, G.H., and Lehr, J.R., 1969, Crystal chemical investigation of natural apatites: American Mineralogist, v. 54, no. 

9-10, p. 1374-1391.

McKelvey, V.E., Armstrong, F.C., Gulbrandsen, R.A., and Campbell, R.M., 1953a, Stratigraphic sections of the Phosphoria 

formation in Idaho, 1947-48, part 2: U.S. Geological Survey 

Circular 301, 58 p.

McKelvey, V.E., Davidson, D.F., O'Malley, F.W., and Smith, 

L.E., 1953b, Stratigraphic sections of the Phosphoria formation in Idaho, 1947-48, part 1: U.S. Geological Survey Circular 208, 49 p.

McKelvey, V.E., Williams, J.S., Sheldon, R.P., Cressman, E.R., 

Cheney, T.M., and Swanson, R.W., 1959, The Phosphoria, 

Park City, and Sheldon Formations in the western phosphate 

field: U.S. Geological Survey Professional Paper 313-A, 47 p.

Piper, D.Z., 1991, Geochemistry of a Tertiary sedimentary phosphate deposit, Baja California Sur, Mexico: Chemical Geology, v. 92, p. 283-316.

Sverdrup, H.U., Johnson, M.W., and Fleming, R.H., 1963, The 

oceans: Their physics, chemistry and general biology: Englewood Cliffs, N.J., Prentice-Hall, p. 237.

Taggart, J.E., Lindsay, J.R., Scott, B.A., Vivit, D.V., Bartel, A.J., 

and Stewart, K.C., 1987, Analysis of geologic materials by 

wavelength-dispersive X-ray fluorescence spectrometry, 

chap. E of Baedecker, P.A., ed., Methods for geochemical 

analysis: U.S. Geological Survey Bulletin 1770, p. E1-E19.

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

elements in some major units of the Earth's crust: Geological Society of America Bulletin, v. 72, no. 2, p. 175-191.

Vinogradov, A.P., and Ronov, A.B., 1956, Composition of the 

sedimentary rocks of the Russian platform in relation to the 

history of its tectonic movements: Geochemistry 1956, no. 6, 

p. 533-559.

Wedepohl, K.H., ed., 1969, Handbook of geochemistry: Berlin, 

Springer-Verlag, 2 v.

A8 The Phosphoria Formation: Its Geochemical and Biological Environment of Deposition
FIGURES 3-8; TABLES 1-6

4

3.5

3

g 2.5

1

0.5

0

ICP AI 2O3 CONTENT, IN WEIGHT PERCENT

y = -0.089012 + 1.1224x R= 0.99607 

 - y = -0.058389 + 1.0565x R= 0.99268

1 1.5 2 2.5 3 

ICP Fe2O3 CONTENT, IN WEIGHT PERCENT

Figure 3. Comparison of measured AI 2O3 (A), P2O5 (B), 

Fe2O3 (O, and CaO (D) contents by different analytical techniques: inductively coupled plasma (ICP) atomic-emission 

spectroscopy, X-ray-fluorescence (XRF) spectroscopy, and 

wet chemical analysis. A, XRF (diamonds) and wet chemical

Jj2E 

^S£

 U Q 

Q X""

50

40

35

-a 30

20

20

 y = 1.3741 + 0.94642x R= 0.9924

- y = 0.27145 + 0.96578x R= 0.99328

5 10 15 20 25 30 35 

ICP P.O. CONTENT, IN WEIGHT PERCENT

 y = -0.77205 + 1.0499x R= 0.9926)

25 30 35 40 45 

ICP CaO CONTENT, IN WEIGHT PERCENT

50

(squares) AI2O3 versus ICP AI2O3 content. B, XRF (diamonds) 

and wet chemical (squares) P2O5 versus ICP P2O5 content. 

C, XRF (diamonds) and wet chemical (squares) Fe2O3 versus 

ICP Fe2O3 content. D, XRF CaO versus ICP CaO content.

Mineral Abundances in Rocks from the Montpelier Section of the Phosphoria Formation, Idaho All
= -0.0054006 + 0.031327x R= 0.93256 T

2 4 6 8 10 

Al.O, CONTENT, IN WEIGHT PERCENT

3.5 

3

t-" § 2.5 

u! 2

?1 1.5 u. >

1

0.5

0

3.5 

3

2.5

t-" w

ll 2

8g °«§ L5

uj ji 

z " i

0.5 

0

Al.O, CONTENT, IN WEIGHT PERCENT

C- Y = 0.015755 + 0.25503X R= 0.95982)_

4 6 8 

A1O CONTENT, IN WEIGHT PERCENT

Figure 4. TiO2 (A), Fe2O3 (fi), and K2O (O versus AI2O3 

content, as determined by inductively coupled plasma atomic-emission spectroscopy. Best-fit curve in figure 46 has been 

drawn visually. Samples with data points falling outside main 

trend contain iron in excess of that contributed by detritus; 

the presence of either iron oxide or pyrite in these samples 

was verified by optical microscope.

A12 The Phosphoria Formation: Its Geochemical and Biological Environment of Deposition
2 4 6 8 10 

INORGANIC-CARBON CONTENT, IN WEIGHT PERCENT

60

50

40

if"

20

C y = -0.63621 + 1.0739x R= 0.99576

10 20 30 40 50 

MEASURED CARBONATE CONTENT, IN WEIGHT PERCENT

60

24 6 8 10 12 

INORGANIC-CARBON CONTENT, IN WEIGHT PERCENT

Figure 5. MgO (A, B) and CaO (B) versus inorganic-carbon 

content, and calculated versus measured carbonate content 

(O- A, MgO content, measured by inductively coupled plasma atomic-emission spectroscopy, versus inorganic-carbon 

content. Slope of curve represents ratio of MgO to inorganic 

carbon in stoichiometric dolomite; shifted up to include all 

data points, curve intercepts y-axis at approximately 0.7 

weight percent MgO. B, CaO (squares) and MgO (diamonds) 

versus inorganic-carbon content. CaO content has been reduced by CaO contents in apatite and detritus; MgO content 

has been reduced by MgO content in detritus. Slopes of 

curves represent ratios of CaO and MgO to inorganic carbon 

in stoichiometric calcite and dolomite, respectively. C, Carbonate content, estimated from calculated abundances of dolomite, calcite, and apatite (see table 4), versus carbonate 

content measured by induction-furnace carbon analysis.

60

50

10

10 15 20 25 30 

P.O. CONTENT, IN WEIGHT PERCENT

35 40

Figure 6. CaO versus P2O5 content in apatite, as determined 

by inductively coupled plasma atomic-emission spectroscopy. Minimums define a curve of slope 1.38 that is interpreted 

to represent a ratio of CaO to ?2^>5 in these samples.

Mineral Abundances in Rocks from the Montpelier Section of the Phosphoria Formation, Idaho A13
50

40

h.

20

10

^ y = -0.53078 H- 1.0224x R= 0.9925 )

2468

A1,O, CONTENT, IN WEIGHT PERCENT

10 20 30 40 

MEASURED SO, CONTENT, IN WEIGHT PERCENT

50

2 4 6 8 10 12 

ICP ALO, CONTENT, IN WEIGHT PERCENT

Figure 7. Residual fraction versus AI2O3 content (A), calculated versus measured SiO2 content (B), calculated SiO2 content versus AI2O3 content measured by inductively coupled 

plasma (ICP) atomic-emission spectroscopy (Q, and calculated versus measured loss on ignition (LOI) (D). In figure 7A,

30

25

20

38

10 15 20 

MEASURED LOI, IN WEIGHT PERCENT

30

minimums define a curve of slope 6.40 that is interpreted to 

represent the ratio of detritus to AI 2O3 ; in figure 1C, minimums define a curve of slope 3.75 that is interpreted to represent the ratio of SiO2 to AI 2O3 to detritus.

A14 The Phosphoria Formation: Its Geochemical and Biological Environment of Deposition
zz-u

[ . . . .. . . .- .. .. .. . .- .. - .. . : Vi > . . . ..- . .. . . . . .. . . . . > .>

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J.HOI3AV NI

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jz;

0

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gs

C/2

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cf

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 T-t

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Mineral Abundances in Rocks from the Montpelier Section of the Phosphoria Formation, Idaho A15
Table 1. Major-element-oxide contents in samples of the Phosphoria Formation in Montpelier Canyon, Idaho

[All values in weight percent, as determined by inductively coupled plasma spectroscopy (I), X-ray-fluorescence spectroscopy (X), and wet chemical 

analysis (W). LOI, loss on ignition]

Sample----

Sio 2 ------

AI 2 0 3 ~--- 

Fe2O 3 -~--

MgO------ 

r* a n

Na 2 O-----

K 2 0------

TJO 2 ------ 

P 2 0 5 ~ 

LOI------

C(inorganic) 

C (orqanic)-

Sample----

Si0 2 ------ 

AI 2 0 3 -----

Fe 2 O 3 -----

MgO------ 

r* a o

Na 2O-----

K 2 O------

TiO 2 ------ 

P 2 0 5 --

MnO------

LOI------

C(inorganic) 

C (orqanic)-

Sample----

SiO 2 ------ 

AI 2 0 3 -*---

Fe 2 O 3 -----

MgO------

P a Cl

Na 2O-----

TiO 2 ------ 

P 2 0 5 --

MnO------

LOI------

C(inorganic) 

C (organic)-

P-2

5.00 (X) 

1.40 (I). 

1.18 (X) 

1-36 (I). 

1.47 (X)

.18 (I), 

.38 (X)

47.59 (I). 

50.60 (X) 

-66 (I). 

.63 (X)

.35 (I). 

.34 (X)

.07 (1). 

.07 (X) 

32.07 (1). 

32.30 (X). 

32.30 (W)

-005 (1). 

.010 (X)

5

7"J

1.23 

.50

P-37

9.17 (I) 

2.70 (1)

.92 (1)

20.15 (I) 

.23 (I)

2.52 (I)

.20 (I)

10.76 (I). 

10.50 (W)

.009 (I)

.85 

5.47

P-82

21.70 (X) 

4.35 (I). 

4.15 (X)

1.86 (I). 

2.06 (X)

.dj (t), 

.48 (X)

34.00 (X) 

.39 (I). 

.47 (X)

1-00 (I). 

1.26 (X) 

.12 (I). 

.22 (X) 

22.91 (I). 

23.60 (X), 

23.40 (W)

.01 (X)

9 PC

.24 

3.63

P-2-1

4.59 (I) 

1.42 (1)

10.60 (I)

20.85 (1) 

.13 (I)

1.24 (1)

.17 (I)

.30 (I). 

3.60 (W)

.017 (1)

P-43

25.50 (X) 

5.67 (1). 

5.48 (X)

1.86 (1). 

2.04 (X)

.71 (I). 

.82 (X)

29.10 (X) 

.32 (I). 

.34 (X)

1.48 (X)

.13 (I). 

.30 (X) 

14.66 (I). 

15.20 (X). 

15.10 (W)

.010 (I). 

.01 (X)

1.51 

5.38

P-87

10.38 (I). 

11.30 (W)

3.63 (I). 

3.6 (W)

.31 (I)

1.16 (I)

«;.3B (i) 

.27 (I)

8.84 (I). 

7.00 (W)

.042 (I)

.15 

2.57

P-4

4.33 (I) 

1.17 (I)

9.98 (I)

24.20 (I) 

.07 (I)

1.16 (I)

.13 (I)

.16 (1). 

.20 (W)

-017 (I)

8.85 

.89

P-45

4.80 (I) 

1.73 (1)

.34 (1)

1.19 (I)

.13 (I)

8.34 (I). 

9.60 (W)

.018 (I)

3.27 

3.84

P-100

32.20 (X) 

7.73 (I). 

6.87 (X)

2.29 (I). 

2.65 (X)

.48 (I). 

.60 (X)

25.70 (X) 

.42 (I). 

.44 (X)

2.41 (I). 

1.83 (X) 

.13 (I). 

.36 (X) 

17.18 (I). 

17.90 (X). 

18.50 (W)

.012 (I). 

.01 (X)

.15 

3.13

P-5

7.58 (I) 

2.40 (I)

.13 (1)

1.84 (I)

.89 (I). 

.70 (W)

.023 (I)

3.99 

1.06

P-46

22.80 (X) 

5.67 (1). 

5.38 (X)

1.86 (I). 

2.05 (X)

.78 (I). 

.93 (X)

30.90 (X) 

.24 (I). 

.31 (X)

1.69 (1). 

1.45 (X)

.12 (1). 

.28 (X) 

15.35 (I). 

16.00 (X). 

15.60 (W)

-008 (I). 

.01 (X)

17, W 

1.78 

5.00

P-103

32.10 (X) 

7.56 (I). 

7.20 (X)

2.86 (I). 

2.96 (X)

.68 (I). 

-74 (X)

21.20 (X) 

.38 (I). 

.39 (X)

2.05 (I). 

1.69 (X) 

.25 (I). 

.38 (X) 

14.20 (1). 

14.20 (X). 

14.20 (W)

.005 (1). 

.01 (X)

16.70 

.14 

6.63

P-7

20.80 (X) 

2.84 (I). 

2.46 (X) 

.86 (I). 

.86 (X)

.27 (I), 

.43 (X)

37.77 (I), 

38.70 (X) 

.23 (I). 

.31 (X)

.80 (I). 

.81 (X)

.05 (1). 

.14 (X) 

25.20 (I). 

25.90 (X). 

25.30 (W)

.010 (X) 

7.55

.62 

2.47

P-52

10.90 (1) 

3.30 (1)

1.45 (1)

6.52 (1) 

.49 (1)

2.82 (1)

.43 (1)

2.68 (1). 

2.70 (W)

.50 

3.84

P-104

14.80 (X) 

2.65 (1). 

2.36 (X)

1.72 (I). 

1.86 (X)

.18 (I). 

.34 (X)

41.80 (X) 

.47 (I). 

.47 (X)

.65 (I). 

.62 (X) 

.07 (I). 

.15 (X) 

29.80 (I). 

29.80 (X). 

29.40 (W)

.007 (I). 

.01 (X)

.25 

1.72

P-7-1

1.12 (I) 

1.26 (I)

39.45 (I) 

.38 (I)

.14 (I)

.05 (I)

5.43 (I). 

5.10 (W)

.018 (I)

P-62

9.24 (I) 

3.00 (I)

1.16 (1)

19.73 (I) 

.20 (I)

.28 (I)

9.05 (I). 

8.60 (W)

.015 (I)

1.41 

3.57

P-105

10.36 (I) 

3.30 (I)

.22 (I)

1.31 (I)

^.ba (i) 

.33 (1)

1.92 (1). 

2.20 (W)

.011 (I)

.01 

1.51

P-10

20.50 (X)

3.21 (I). 

2.91 (X) 

1.04 (I). 

1.01 (X) 

 } } /It

.51 (X)

35.70 (X) 

.19 (1). 

.29 (X)

.92 (1). 

.90 (X)

.10 (1). 

.19 (X) 

22.19 (I). 

24.40 (X). 

24.10 (W)

.002 (I). 

.010 (X) 

11.20

.29 

4.66

P-64

-28 (1). 

.30 (W)

.14 (1). 

.06 (W)

<a CO Ml

52.60 (1) 

-07 (1)

.06 (1)

.01 (1)

3.05 (1). 

2.90 (W)

.008 (1)

10.72 

1.81

P-129

6.22 (I). 

7.00 (W)

2.10 (I). 

2.3 {W)

.55 (I)

27.14 (I) 

.47 (1)

1 -OO \\)

.20 (1)

18.71 (I). 

17.40 (W)

.015 (1)

.32

1.49

P-11

1.91 (i) 

.40 (1) 

1.92 (I)

.07 (I)

.57 (1) 

.05 (1)

2.20 (1). 

2.40 (W)

.021 (I)

P-69

19.80 (X) 

4.54 (I). 

4.40 (X). 

4.30 (W) 

1.57 (I). 

1.76 (X). 

1.83 (W)

.43 (I). 

.56 (X)

34.00 (X) 

.42 (I). 

.46 (X)

1.45 (1), 

1.23 (X)

.10 (1). 

.24 (X) 

21.54 (I). 

21.90 (X). 

22.20 (W)

.006 (1). 

.01 (X)

.62 

4.79

P-131

3.70 (X) 

.40 (I). 

.30 (X). 

.40 (W) 

.41 (I). 

.35 (X). 

.3 (W)

.08 (I). 

.26 (X)

50.40 (I). 

53.10 (X) 

-13 (I). 

.18 (X)

.10 (I). 

.08 (X) 

.02 (I). 

0 (X) 

38.95 (I). 

36.80 (X). 

36.40 (W)

.003 (I). 

.01 (X)

.65 

.83

P-21

9.58 (I) 

2.75 (I) 

1.57 (I)

10 no f|\

-26 (1)

3

1ft /l\

.30 (I)

6.87 (I). 

6.80 (W)

.012 (I)

1.00 

2.20

P-71

12.60 (X) 

3.02 (1), 

2.94 (X), 

2.80 (W) 

1.12 (I), 

1.23 (X), 

1.25 (W)

.53 (I), 

.70 (X)

38.30 (X) 

.28 (I), 

.33 (X)

.92 (I), 

.84 (X)

.08 (I), 

.14 (X) 

21.76 (I), 

22.50 (X), 

22.40 (W)

.004 (I), 

.01 (X)

17.10 

1.29 

6.50

P-140

8.11 (I) 

2.50 (I)

1.71 (I)

17.07 (1) 

.80 (1)

1.60 (I) 

.23 (I)

9.21 (1). 

8.70 (W)

.028 (1)

1.03 

.95

P-24

27.80 (X)

4.54 (I). 

4.34 (X) 

1.57 (I). 

1.65 (X)

O 1 A ll\

2.38 (X)

28.00 (X) 

.27 (1). 

.38 (X) 

1.33 (I).

1.47 (X) 

-13 (I).

-25 (X) 

14.43 (I). 

14.90 (X). 

14.70 (W) 

.007 (1).

.010 (X) 

14.00

1.50 

3.24

P-77

8.94 (1) 

3.12 (1)

-31 (I)

16.79 (I) 

.93 (I)

.27 (I)

11.47 (I). 

10.60 (W)

.14 

3.15

P-141

4.74 (I) 

1.67 (I)

1.00 (I)

34.00 (I) 

.92 (I)

.81 (1) 

.20 (1)

2.89 (1). 

2.60 (W)

.037 (1)

6.00 

.75

P-28 P-32

3.02 (1). 6.24 (1). 

2.93 (X) 5.75 (X) 

1.04 (I). 1.86 (1). 

1.08 (X) 1.97 (X) 

1.04 (I). 2.16 (1).

1.18 (X) 2.25 (X)

AC »\-j i\\ o~7 no M\

37.80 (X) 27.90 (X) 

.22 (1). .24 (1). 

.25 (X) .30 (X) 

.88 (1). 1.69 (I).

.80 (X) 1.64 (X) 

.08 (I). .18 (I).

.13 (X) .28 (X) 

15.81 (1). 14.20 (1). 

16.10 (X). 14.10 (X). 

16.30 (W) 13.30 (W) 

.007 (I). .014 (I).

.010 (X) .01 (X)

3.01 2.15 

6.31 4.46

P-78 P-79

28.80 (X) 

6.99 (I). 2.78 (I) 

6.57 (X)

2.29 (I). .89 (I) 

2.45 (X)

.53 (I). 13.40 (I) 

.60 (X) 

oe en /i\ on cc /i\

26.30 (X) 

.34 (I). .28 (I) 

.41 (X)

2.17 (1). .95 (1) 

1.84 (X)

.15 (I). .08 (1) 

.34 (X) 

16.95 (I). 5.57 (1). 

17.30 (X). 4.80 (W) 

17.50 (W)

.011 (I). .030 (I) 

.01 (X)

.37 7.89 

4.72 1.49

P-146 P-148

3.88 (X) 5.98 (X) 

.19 (I). 1.13 (I). 

.14 (X). .99 (X). 

.30 (W) .80 (W) 

.14 (I). .57 (I). 

.06 (X). .51 (X), 

.08 (W) .34 (W)

. 3-3 \\], .f-3 (>),

.48 (X) .38 (X)

54.58 (1). 47.57 (1), 

53.50 (X) 49.10 (X) 

.08 (I). .20 (I). 

0 (X) .21 (X)

0 (I). .31 (I). 

.04 (X) .26 (X) 

0 (I). .05 (I). 

0 (X) .03 (X) 

13.52 (I). 34.37 (I). 

12.20 (X). 32.90 (X). 

12.10 (W) 33.10 (W)

.032 (I), .004 (I). 

.01 (X) .01 (X)

7.68 .91 

.82 2.19

A16 The Phosphoria Formation: Its Geochemical and Biological Environment of Deposition
Table 1. Major-element-oxide contents in samples of the Phosphoria Formation in Montpelier 

Canyon, Idaho Continued

[All values in weight percent, as determined by inductively coupled plasma spectroscopy (I), X-ray-fluorescence 

spectroscopy (X), and wet chemical analysis (W). LOI, loss on ignition]

Sample---- P-157 

25.40 (X) 

4.16 (I), 

3.99 (X) 

1-57 (I), 

1.63 (X) 

1.06 (I), 

1.19 (X) 

32.18 (I). 

34.50 (X) 

.54 (I), 

.53 (X) 

.95 (I), 

.87 (X) 

.13 (I). 

.26 (X) 

20.85 (I), 

22.20 (X), 

16.60 (W) 

 013 (I), 

.01 (X) 

7.62 

1.07 

1.60

P-163 P-165 P-168 

31.60 (X) 

1.89 (I). 

1.78 (X) 

1.22 (I). 

1.25 (X) 

.30 (I), 

.42 (X) 

33.64 (I), 

34.60 (X) 

.27 (I). 

.29 (X) 

.41 (I), 

.37 (X) 

.05 (I). 

.10 (X) 

21.99 (I). 

22.10 (X). 

21.20 (W) 

 010 (I). 

.01 (X) 

5.48 

.94 

1.03

P-168a U-4 U-7 U-12 R-22

AI 2 0 3 -----

Fe 2 C>3-----

MgO------

CaO------

Na 2 O-----

P 2 0 5 »

MnO------

10.11 (I)

3.23 (I)

.62 (I)

4.70 (I)

1.20 (I)

1.96 (I)

.37 (I)

.34 (I).

.70 (W)

8.92 (I)

2.76 (I)

.81 (I)

15.25 (I)

.74 (I)

1.84 (I)

.32 (I)

6.62 (I),

6.30 (W)

1.93 (I)

1.24 (I)

.31 (I)

35.11 (I)

.28 (I)

.37 (I)

.07 (I)

23.59 (I),

21.20 (W)

5.86 (I)

2.37 (I)

8.59 (I)

22.24 (I)

.31 (I)

1.48 (I)

.18 (I)

.71 (I),

.90 (W)

6.95 (I)

3.20 (I)

1.54 (I)

8.97 (I)

.78 (I)

1.59 (I)

.23 (I)

2.52 (I).

2.40 (W)

.056 (I) .016 (I) .010 (I) .117 (I) .046 (I)

LOI------

C(inorganic) 

C (organic)-

.68 

.65

1.07

2.41

6.19 

.61

1.13 

.98

43.20 (X)

3.78 (I),

3.76 (X)

2.14 (I).

2.26 (X)

.53 (I).

.63 (X)

25.22 (I), 12.68 (I) 

25.90 (X) 

.62 (I). 

.60 (X) 

.90 (I). 

.87 (X) 

.12 (I). 

.16 (X) 

15.81 (I), 

16.50 (X). 

16.30 (W) 

.037 (I). 

.01 (X) 

4.77 

.70 

.70

.47 (I)

2.27 (I)

.48 (I)

.05 (!)

.10 (I)

.01 (I)

.30 (I). 

.40 (W)

.039 (I)

2.53 

.30

Mineral Abundances in Rocks from the Montpelier Section of the Phosphoria Formation, Idaho A17
Table 2. Minor-element contents in samples of the Phosphoria Formation in Montpelier Canyon, Idaho 

[All values in parts per million. Elements below the limits of detection in more than half the samples are omitted]

Sample

Ag----- 

As-----

Ba---- 

/** ^

Ce----- 

Co-----

Cr---- 

Cu---- 

La-----

Li-----

Mo---- 

Nd---- 

Ni----- 

Pb----

Q rSr---- 

V----- 

Y-----

Yb---- 

Zn----

Sample

Ag----- 

As----- 

Ba---- 

Cd----- 

Ce----- 

Co-----

Cr---- 

Cu---- 

La----- 

Li-----

Mo---- 

Nd---- 

Ni----- 

Pb----

C o

Sr---- 

V----- 

Y-----

Yb---- 

Zn----

Sampte

Ag----- 

As----- 

Ba---- 

Cd-----

/** A

/** «*

Cr---- 

Cu---- 

La----- 

Li----- 

Mo---- 

Nd---- 

Ni----- 

Pb---- 

Sc----- 

Sr---- 

V----- 

Y----- 

Yb---- 

Zn----

P-2

0

30 

51 

5

58 

3

410 

22

1 Qft

10 

130 

60 

9 

5

690 

180

o 1 n

13 

400

P-37

30 

239 

3 

47 

5

2,320 

114 

128

1 1

20 

85 

325 

9 

1 1

1,030 

164 

160

8 

1,070

P-82

13 

40 

1 10 

94

C 4

4

1.600 

140 

260 

16 

19 

180 

210 

10 

13 

1,400 

550 

420 

21 

1.400

P-2-1

0

10 

95 

20

18 

4

158 

28 

14

1 1

8 

17 

58 

8

4

110 

337 

14

2 

460

P-43

5

30 

170 

3 

43 

5

1,300 

100 

150

1

0

24 

90 

210 

6

1,200 

130

4 Q fi

8 

910

P-87

12 

40 

198 

36

K K

12

1,090 

118 

99 

1 1 

27 

73 

403 

14 

10 

595 

374 

124 

6 

1,650

P-4

0

0 

90

1 **

13 

3

135 

14 

10

1 2

3 

1 3 

80 

8 

4

104 

192 

10

1 

590

P-45

20 

132 

3 

36 

5

1,020 

57 

96 

12

16 

62 

163 

5 

6

780 

99 

109

5 

572

P-100

6 

30 

180 

24

7

1,500 

1 10 

160 

25 

18 

110 

160 

10 

10 

1,300 

190 

210 

9 

1.200

P-5

2

20 

177

44

7

403

46 

o n

o c

13 

36 

263 

12

128 

744 

27

3 

1,670

P-46

7

20 

160 

12 

43

4

1,500 

110 

150 

22

52 

92 

260 

9 

10

1,200 

210 

220

10 

1,100

P-103

19 

40 

220 

130

K 7

4

3,900 

200 

320 

41 

8 

170 

170 

15 

15 

1,100 

590 

380 

16 

1,200

P-7

9

20 

94 

41

22 

2

860 

77 

76

1 1

47 

44 

170 

1 1 

5

630 

1,100 

120

5 

1,100

P-52

20 

324 

5 

64 

9

1 ,380 

68 

78

O £

41 

63 

394 

12

12 

783 

779

9 O

6 

1,950

P-104

5 

20 

97 

50

75

4 

980 

56 

310 

8 

7 

230 

55 

9 

1 3 

1,700 

320 

470 

18 

510

P-7-1

0

0 

26

13

g

163 

29 

47

3 

34 

40 

0 

2

429

90

c c

3 

146

P-62

30 

202 

77 

51

7

1,760 

93 

128

84 

89 

418 

9

I O

615 

1,060

146 

7 

2,940

P-105

0 

30 

291 

59

71

6 

478 

34 

52 

10 

1 5 

46 

145 

1 1 

9 

137 

389 

70 

5 

1,040

P-10

10

20 

120 

120

29 

2

1,100 

110 

110

14

29 

62 

190 

13

650 

2,800 

170

8 

1,400

P-64

0

0 

14 

80 

0 

2

181 

21 

12 

0

8 

22 

53 

0 

0

788 

393 

17

1 

672

P-129

12 

30 

197 

48

3 O

1,000 

80 

118 

18 

22 

70 

1 14 

1 1 

8 

639 

535 

203 

10 

1,530

P-11

4

0 

32 

i a

12 

2

221 

23

?Q

8 

31 

161 

4 

0

305 

162

1 O

2 

1,250

P-69

30 

120

7 

53 

4

1,500 

140 

240 

14

25 

140 

310 

8 

10

1,400 

170

n C fi

1 5 

1,700

P-131

2

1 

51 

23 

17

2 

430 

29 

110 

2 

3 

60 

17 

7 

6 

1,100 

560 

230 

1 1 

210

P-21

50 

245 

1 7

55

1,140 

82 

129

O K.

25 

82 

293 

1 1 

1 1

285 

431 

172

9 

1,630

P-71

7

30 

96 

5

38 

3

2,100 

190 

220 

16

33 

120 

280 

6 

10

1,400 

200

14 

1,500

P-140

5 

20 

212

10 

c c

543 

40 

71 

18 

17 

49 

125 

10 

7 

374 

258 

93 

5 

1.330

P-24

1 1

30 

140 

K. a

43 

3

1,100 

140 

160

15

77 

100 

340 

12 

9

600 

810 

270

13 

2,000

P-77

5

30 

226 

40 

65

1.320 

86 

123 

15

7 

80 

168 

1 1 

10

715 

330

1 1 C

7 

844

P-141

3 

20 

124 

42

O U

5

235 

23 

33 

8 

9 

33 

65 

5 

5 

259 

178 

44 

3 

734

P-28

7

20 

85 

12

26 

4

1,700 

160 

120

14

37 

71 

260 

5 

9

1,200 

190 

190

9 

1.200

P-78

40 

150 

75 

50

7

1,900 

140 

170 

o c

29 

99 

320 

9 

1 1

1.200 

500

O A F\

1 1

1,600

P-146

0 

1 

28 

97

0

2 

270 

15 

22 

0 

0 

8 

1 3 

0 

2 

540 

340 

29 

1 

230

P-32

5

40 

180 

0

41

1,200 

87 

120

1 **

20 

72 

270 

7 

1 1

1,200 

140 

H £ n

7 

1,300

P-79

4

20 

61 

57 

21

405 

25 

66 

4

9 

46 

149 

5 

4

356 

334

a c

4 

722

P-148

5 

10 

120 

60

10

2 

930 

70 

60 

6 

4 

31 

36 

6 

6 

1.200 

860 

120 

5 

450

A18 The Phosphoria Formation: Its Geochemical and Biological Environment of Deposition
Table 2. Minor-element contents in samples of the Phosphoria Formation in Montpelier Canyon, 

Idaho Continued

Sample

Ag-----

As-----

Ba----

Cd-----

Ce-----

/** C «* o - - - - -

Cr----

Cu----

La-----

Li-----

Mo----

Nd----

Ni-----

Pb----

Sc-----

Sr----

V-----

Y-----

Yb----

Zn----

P-157

0

10

210

3

77

4

530

36

270

7

150

65

8

9

700

81

480

20

270

P-163

0

10

251

3

51

9

195

21

32

1 7

3

30

87

14

9

95

80

29

3

129

P-165

3

10

277

18

65

6

1,280

68

148

O Q

C. O

8

109

1 15

1 1

10

237

227

249

14

370

P-168

0

1

120

5

66

2

600

32

340

3

250

43

6

8

750

150

630

29

220

P-168a

0

0

124

5

70

0

O

634

32

382

3

267

50

8

6

824

154

642

30

212

U-4

0

0

157

0

20

5

355

13

21

27

14

23

45

5

6

158

74

26

2

38

U-7

0

0

162

0

40

6

475

46

52

o q O 9

4

40

74

4

7

1 17

96

68

4

604

U-12

0

1

280

0

43

4

320

37

87

24

3

58

51

0

5

290

58

130

6

320

R-22

0

0

1 4

0

0

4

49

44

8

4

0

7

1 5

0

0

95

22

9

0

35

Mineral Abundances in Rocks from the Montpelier Section of the Phosphoria Formation, Idaho A19
Table 3. Shale compositions

[Major-element-oxide contents in weight percent; minor-element contents in parts per million. Dashes, no 

data. Data on worldwide shales and mainly geosynclinal shales from Wedepohl (1969), on Russian platform 

shales from Vinogradov and Ronov (1956), on detrital fraction of the Monterey Formation from Isaacs 

(1980), and on Cretaceous black shales from Brumsack (1986)]

Detrital 

fraction of

the

Phosphoria 

Formation

Worldwide 

shales

Mainly 

geosynclinal 

shales

Russian

platform

shales

Detrital 

fraction of

the

Monterey 

Formation

Cretaceous 

black shales

Major-element oxides

SiO 2 ----- 58.5 58.4 58.9 50.7

Al2O 3 ..-- 15.6 15.1 16.7 15.1

Fe2O3-.. 4.81 6.75 6.9 6.7

MgO----- 2.34 2.5 2.6 3.3

CaO----- 3.90 3.09 2.2 7.2

Na 2 O---- - - - 1.29 1.6 .8

K 2 O----- 3.98 3.20 3.6 3.5

TiO 2 ----- .48 .77 .78 .78

P 2 O5 - .16 .16 .16 .10

MnO----- ______JJ_____.09_____.08

	Minor elements

Ag------ ~(TOT ~ :~^~

As------ - - - 13 - - - - - -

Ba------ - - - 580 - - - - - -

Cd------ - - - .3

Ce------ --- 59 2 70 3 98

Co------ - - - 19 - - - - - -

Cr------ - - - 90 - - - - - -

Cu------ - - - 45 - - -

La------ - - - 92 232 3 50

Li------ --- 66

Mo------ - - - 2.6 - - - - - -

Nd------ - - - 24 231 3 44

Ni------ - - - 68 - - - - - -

Pb------ - - - 20 - - - - - -

Sc------ - - - 13 - - - - - -

Sr------ - - - 300 - - - - - -

V------- - - - 130

Y------- - - - 26 2 27 3 49

Yb------ - - - 2.6 23.1 3 4.2

Zn------ - - - 95 - - -

62.2

17.8

3.6

2.0

1.4

2.5

3.6

5.3

.5

.13

10.0

70.0

28.0

40.0

H15.0

1 Heinrichs and others (1980). 

2 Haskin and Haskin (1966). 

3 Balashov and others (1964).

A20 The Phosphoria Formation: Its Geochemical and Biological Environment of Deposition
Table 4. Formulas used in normative calculations

Mineral Component Explanation Formula

Apatite- P2O5/apatite ratio is 0.406,

assuming that the stoichiometry 

for carbonate fluorapatite is 

Ca5 (P04)2.87(C03)o.i3Fi.i3 

and that all the P2Os is in 

apatite, except 0.16 weight 

percent in detritus.

P2O5-0.01A12O3 

0.406

Dolomite------- Dolomite is calculated from MgO

analyses assuming that 21.9 

weight percent is in dolomite 

and 2.3 weight percent in 

detritus.

MgO-0.15Al2O3

0.219 

If MgO<0.15Al2O3, then dolomite=0

Calcite- Calcite is calculated from CaO 

analyses after initially 

subtracting out the CaO in 

apatite (55.5 weight percent), 

dolomite (30.4 weight percent), 

and detritus (3.9 weight 

percent). CaO is 56 weight 

percent of calcite.

CaO-0.25Al2O3-0.555Apatite-0.304 Dolomite 

0.56

Organic matter- - - - Multiplication factor is adjusted 

from data of Isaacs (1980) after 

iterative calculation.

1.7Organic Carbon

Detritus- Detritus/Al2O3 ratio, 6.40, is 

determined from plot of 

residuals versus A12O3 content. 

(The residual is that proportion 

of the rock which remains after 

the proportions of calcite, 

dolomite, apatite, and organic 

matter are subtracted.)

6.40A12O3

Total silica------ Total silica content from ICP data is

calculated by subtracting from 

100 major oxides and an LOI 

term; fluorine content is 

calculated from apatite 

abundances and adjusted for 

charge balance and 1, which 

represents sulfur and other 

significant minor elements. LOI 

term includes CO2 in carbonates 

and organic matter and structural 

water in detritus.

100-(Sum of major oxides+LOI+0.0247Apatite+l)

LOI=0.55Al2O3+3.66Inorganic Carbon+

1.7Organic Carbon

Biogenic silica- - - - Biogenic/diagenic silica is calculated 

by subtracting quartz and silica 

contents in detritus from total 

silica content calculated above. 

Quartz and silica contents in 

detritus are determined from 

slope (3.75) of well-defined 

minimum line when total silica 

is plotted against A12O3 

content.

Total Silica-3.75A12O3

Mineral Abundances in Rocks from the Montpelier Section of the Phosphoria Formation, Idaho A21
Table 5. Mineral abundances in samples of the Phosphoria Formation in Montpelier Canyon, Idaho

[All values in weight percent]

Sample

P-2

P-2-1

P-4

P-5

P-7

P-7-1

P-10

P-11

P-21

P-24

P-28

P-32

P-37

P-43

P-45

P-46

P-52

P-62

P-64

P-69

P-71

P-77

P-78

P-79

P-82

P-87

P-100

P-103

P-104

P-105

P-129

P-131

P-140

P-141

P-146

P-148

P-157

P-163

P-165

P-168

P-168a

U-4

U-7

U-12

R-22

Dolomite

0

45.3

42.6

4.2

0

49.4

0

7.5

.6

6.7

2.7

5.6

0

0

6.3

0

0

0

15.9

0

.4

0

0

59.3

0

0

0

0

0

0

0

.1

2.3

1.3

1.4

.3

2.0

0

0

.1

.1

35.2

2.3

0

1.9

Calcite

6.1

10.0

17.9

28.8

4.7

29.9

4.4

75.7

3.7

6.6

23.6

9.6

5.8

14.3

15.7

12.6

.5

9.2

77.7

5.5

10.4

0

3.1

6.0

0

0

2.3

2.1

0

0

.2

0

3.4

50.9

63.6

.4

3.7

3.3

7.3

5.5

4.3

16.4

5.7

4.9

20.7

Apatite

79.0

.6

.3

2.0

62.0

13.3

54.6

5.4

16.7

35.4

38.9

34.8

26.3

36.0

20.4

37.7

6.3

22.1

7.5

52.9

53.5

28.0

41.6

13.6

56.3

21.5

42.1

34.8

73.3

4.5

45.9

95.9

22.5

7.0

33.3

84.6

51.2

.6

16.1

54.1

58.1

1.6

6.0

38.8

.7

Organic 

matter

.9

1.5

1.8

4.2

7.9

3.7

5.5

10.7

7.6

9.3

9.1

6.5

8.5

6.5

6.1

3.1

8.1

11.1

5.4

8.0

2.5

6.2

4.4

5.3

11.3

2.9

2.6

2.5

1.4

1.6

1.3

1.4

3.7

2.7

1.1

4.1

1.8

1.0

1.7

1.2

.5

Detritus

9.0

29.4

27.7

48.5

18.1

7.1

20.6

12.2

61.3

29.0

19.4

39.9

58.7

36.3

30.7

36.3

69.8

59.1

1.8

29.0

19.4

57.2

44.8

17.8

27.8

66.4

49.5

48.4

16.9

66.3

39.8

2.5

51.9

30.4

1.2

7.3

26.6

64.7

57.1

12.1

12.3

37.5

44.5

24.2

3.0

Biogenic 

SiO2

2.0

12.6

14.3

10.8

13.3

11.5

16.6

4.8

1.3

0

4.6

17.5

3.6

15.0

2.4

0

4.2

4.8

9.9

2.5

1.7

8.7

8.0

1.6

3.5

5.9

28.6

10.7

.6

16.9

8.9

0

0.5

11.8

29.3

15.0

24.6

27.4

8.2

37.3

28.9

70.8

A22 The Phosphoria Formation: Its Geochemical and Biological Environment of Deposition
Table 6. Correlation coefficients for rock components and minor elements

Dolomite- - - -

Calcite- - - - -

Apatite- - - - -

Organic matterDetritus- - - -

Bioqenic silicaAq- ------

As- ----- -

Ba- ----- -

Cd- ----- -

Ce- ----- -

Co- ----- -

Cr- ----- -

Cu- ----- - 

La- ------

Li- ------

Mo- ----- - 

Nd- ----- -

Nj- ----- -

Pb- ----- -

Sc- ----- -

Sr- ----- -

V- ----- .

Y- ----- - 

Yb- ----- -

Zn- ------

Dolomite

1

.17

-.36

-.25

-.18

-.1

-.24

-.28

-.29

-.02

-.41

-.19

-.31

-.33

-.17

-.31

-.18

-.24

-.38

-.32

-.13

. o c.

-.33

-.21

Calcite

1

-.34

-.18

-.4

-.1

-.36

-.38

-.47

.19

-.6

-.25

-.33

.01 

-.43

-.35

-.ID

-.41

-.26

-.59

-.6

-.18

-.12

-.4 

-.42

-.2

Apatite

1

.18

-.51

-.41

.25

.12

-.32

.13

.08

-.48

.21

.56

-.3

.04 

.51

-.13

.05

.17

.68

.24

. bo 

.58

-.06

Organic 

matter

1

.19

-.41

.66

.58

.13

.16

.17

.02

.87

. oy 

.43

.36

.49 

> .32

.66

.27

.6

.67

.2

.29 

.28

.53

Detritus

1

.03

.26

.49

.87

-.1

.62

.8

.33

.2 

-.05

.67

-.03

.56

.64

.61

-.22

-.04

~ . 1 O

-.1

.47

Biogenic 

silica

1

-.33

-.38

.1

-.29

-.04

.14

-.4

-.29 

-.25

.03

- . £ O

-.21

-.28

-.18

-.31

-.57

-.14

-.21 

-.18

-.29

Ag

1

.71

.16

.48

.3

.12

.77

. O J

.43

.34

.51

.34

.61

.59

.6

.46

.41

. O 1

.32

.66

As

1

.31

.24

.52

.34

.64

.67 

.39

.29

.44 

.34

.71

.59

.68

.4

.15

.25 

.26

.7

Ba

1

-.18

.67

.62

.28

.11 

.06

.64

.14 

.07

.37

.52

.58

-.21

-.04

- . U O

.05

.29

Cd

1

-.08

-.23

.29-

.27 

.1

-.05

.15 

.06

.07

.23

.08

.13

.64

.04 

.04

.31

Ce

1

.48

.38

.63

.4

.12 

.67

.33

.64

.76

.17

-.1

.57 

.61

.31

Co

1

.1

.07 

-.13

.44

.16 

-.07

.49

.43

.42

-.2

-.18

-.21 

-.16

.36

Cr

1

.58

.56

. O <y

.47

.58

.43

.76

.6

.15

.41 

.41

.52

Dolomite- - - -

Calcite- - - - -

Apatite- - - - -

Organic matterDetritus- - - -

Biogenic silicaAq- ------

Ba- ------

Cd- ------

oe- ------ 

Co- ----- -

Cr- ----- - 

Cu- ----- -

La- ----- -

U- ------

Mo- ----- -

Nd- ------

Ni- ------ 

DISC- ----- -

Sr- ----- -

V- ------ 

Y- ------

Yb- ----- - 

Zn- ------

Cu

1

.52

.41

.51

.4

.66

.OO

.64

.62

.22 

.39

.39

.61

La

1

.15

.11

.97

.17

. O

.65

.64

- . U O

.97

.95 

.15

Li

1

.22

.11

.4

.OO

.57

-.06

0 

.01

.06 

.36

Mo

1

.08

.76

. O O

.39

.2

. O O

.06

.08 

.79

Nd

1

.13

.29 

.63

.59

-.07 

.96

.95 

.12

Ni

1

.48 

.6

.27

.05

.08 

.88

Pb

1 

.65

.06

. o y 

.22

.27 

.49

Sc

1

.49

. u o 

.53

.56 

.54

Sr

1

. uo 

.59

.53 

.23

V

1 

-.03

-.02 

.42

Y

1

.99 

.04

Yb

1 

.07

Zn

1

Mineral Abundances in Rocks from the Montpelier Section of the Phosphoria Formation, Idaho A23

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