Geochemistfy of Minor Elements in 

the „ . , . Monterey ,..,„. „ - , y Formation, • 7 California: .. . . •

on

U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1566
AVAILABILITY OF BOOKS AND MAPS OF THE U.S. GEOLOGICAL SURVEY

Instructions on ordering publications of the U.S. Geological Survey, along with prices of the last offerings, are given in the currentyear issues of the monthly catalog "New Publications of the U.S. Geological Survey." Prices of available U.S. Geological Survey 

publications released prior to the current year are listed in the most recent annual "Price and Availability List." Publications that are 

listed in various U.S. Geological Survey catalogs (see back inside cover) but not listed in the most recent annual "Price and Availability 

List" are no longer available.

Reports released through the NTIS may be obtained by writing to the National Technical Information Service, U.S. Department of 

Commerce, Springfield, VA 22161; please include NTIS report number with inquiry.

Order U.S. Geological Survey publications by mail or over the counter from the offices given below.

BY MAIL OVER THE COUNTER

Books

Professional Papers, Bulletins, Water-Supply Papers, Techniques of Water-Resources Investigations, Circulars, publications 

of general interest (such as leaflets, pamphlets, booklets), single 

copies of Earthquakes & Volcanoes, Preliminary Determination of 

Epicenters, and some miscellaneous reports, including some of 

the foregoing series that have gone out of print at the Superintendent of Documents, are obtainable by mail from

U.S. Geological Survey, Information Services

Box 25286, Federal Center

Denver, CO 80225

Subscriptions to periodicals (Earthquakes & Volcanoes and 

Preliminary Determination of Epicenters) can be obtained ONLY 

from the

Superintendent of Documents

Government Printing Office

Washington, DC 20402

(Check or money order must be payable to Superintendent of 

Documents.)

Maps

For maps, address mail orders to

U.S. Geological Survey, Map Distribution

Box 25286, Bldg. 810, Federal Center

Denver, CO 80225

Residents of Alaska may order maps from

U.S. Geological Survey, Earth Science Information Center

101 Twelfth Ave., Box 12

Fairbanks, AK 99701

Books and Maps

Books and maps of the U.S. Geological Survey are available 

over the counter at the following U.S. Geological Survey offices, 

all of which are authorized agents of the Superintendent of Documents.

• ANCHORAGE, Alaska--4230 University Dr., Rm. 101

• LAKEWOOD, Colorado—Federal Center, Bldg. 810

• MENLO PARK, California—Bldg. 3, Rm. 3128, 345 Middlefield Rd.

• RESTON, Virginia—National Center, Rm. 1C402, 12201 

Sunrise Valley Dr.

• SALT LAKE CITY, Utah—Federal Bldg., Rm. 8105, 125 

South State St.

• SPOKANE, Washington—U.S. Post Office Bldg., Rm. 135, 

W 904 Riverside Ave.

• WASHINGTON, D.C.—Main Interior Bldg., Rm. 2650, 18th 

and C Sts., NW.

Maps Only

Maps may be purchased over the counter at the U.S. Geological Survey offices:

• FAIRBANKS, Alaska—New Federal Building, 101 Twelfth 

Ave.

• ROLLA, Missouri—1400 Independence Rd.

• STENNIS SPACE CENTER, Mississippi—Bldg. 3101
Geochemistry of Minor Elements in 

the Monterey Formation, California: 

Seawater Chemistry of Deposition

By D.Z. Piper and C.M. Isaacs

U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1566

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1995
U.S. DEPARTMENT OF THE INTERIOR 

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY 

Gordon P. Eaton, Director

For sale by

U.S. Geological Survey, Map Distribution

Box 25286, MS 306, Federal Center

Denver, CO 80225

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

Library of Congress Cataloging-in-Publication Data

Piper, David Z.

Geochemistry of minor elements in the Monterey Formation, California: seawater chemistry of decomposition / by D.Z. Piper and 

C.M. Isaacs.

p. cm. — (U.S. Geological Survey professional paper ; 1566) 

Includes bibliographical references (p. 36-41) 

Supt. of Docs, no.: I 19.16:1566

1. Geochemistry—California—Monterey Formation. 2. Geology, Stratigraphic—Miocene. 3. Monterey Formation (Calif.). I. Isaacs, 

Caroline M. II. Title. III. Series. 

QE515.P54 1995

551.46'083432—dc20 95-31300

CIP
CONTENTS

Abstract ..................................................................................................................... 1

Introduction................................................................................................................. 1

Analytical procedures ................................................................................................ 2

Review: Elemental sources—the modern ocean ..................................................... 2

Detrital source.................................................................................................... 7

Marine source..................................................................................................... 7

Biogenic source.......................................................................................... 7

Hydrogenous source................................................................................... 11

Diagenetic overprint........................................................................................... 18

Results: Elemental host phases—the Monterey Formation.................................... 19

Detritus................................................................................................................ 20

Carbonates .......................................................................................................... 20

Sulfur phases ...................................................................................................... 20

Organic matter.................................................................................................... 20

Apatite................................................................................................................. 23

Miscellaneous..................................................................................................... 28

Discussion: Elemental sources—the Monterey ocean ............................................ 28

Terrigenous source............................................................................................. 30

Marine source..................................................................................................... 30

Paleoceanography............................................................................................... 35

Conclusions................................................................................................................. 35

References cited ......................................................................................................... 36

FIGURES

1. Stratigraphic sections of the Monterey Formation at Naples Beach and Lions Head, Calif ..................... 5

2. Plots of intraelement ratios for Fe2O3 , Cr, and Ba........................................................................................ 6

3. Schematic diagram illustrating seawater and sediment chemistry in shelf and basin environments ........ 14

4. Chart showing generalized summary of elemental accumulation in marine sediment............................... 17

5. Zn:Cu interelement ratio in modern marine organic matter and sediment.................................................. 18

6-15. Plots of:

6. Contents of selected major-element oxides and minor elements versus detritus content................. 21

7. Contents of organic matter, Fe2O3 , and Ba versus S content.............................................................. 24

8. Contents of selected minor elements versus organic-matter content, with samples grouped

by lithology.......................................................................................................................................... 25

9. Contents of selected minor elements versus organic-matter content, with samples grouped

by site ........................................................ 26

10. Contents of selected minor elements versus apatite content................................................................ 27

11. Rare-earth-element patterns of samples ................................................................................................. 28

12. La content and Ce anomaly versus apatite content............................................................................... 29

13. Cr versus organic-matter contents.......................................................................................................... 29

14. Contents of selected minor elements versus Cu content...................................................................... 31

15. Cd versus Cu contents ............................................................................................................................. 34

TABLES

1. Major-element-oxide contents in the Monterey Formation........................................................................... 3

2. Minor-element contents in the Monterey Formation ..................................................................................... 4

3. Correlation coefficients for major-element oxides in the Monterey Formation.......................................... 8

4. Correlation coefficients for selected minor elements in the Monterey Formation...................................... 10

III
IV CONTENTS

5. End-member major-element-oxide and minor-element contents in sedimentary fractions of the

Monterey Formation in comparison with standards................................................................................... 11

6. Major components in sedimentary rocks of the Monterey Formation at Naples Beach and

Lions Head, Calif.......................................................................................................................................... 12

7. Weight ratios of minor elements to Fe in fecal matter, shale, and plankton............................................... 12

8. Minor-element contents in organic matter and seawater............................................................................... 12

9. Half-cell reactions, assuming equilibrium conditions.................................................................................... 15

10. Correlation coefficients for major components and minor elements in the Monterey Formation............. 22

11. Factor analysis for major components in sedimentary rocks of the Monterey Formation,

using the computer program Statview II (oblique-solution primary-pattern matrix).............................. 23
Geochemistry of Minor Elements in

the Monterey Formation, California:

Sea water Chemistry of Deposition

By D.Z. Piper and C.M. Isaacs

ABSTRACT

We have analyzed samples of the Monterey Formation 

of southern California, collected at one site in the Santa 

Barbara-Ventura Basin and at another in the Santa Maria 

Basin, for major-element oxides and minor elements. Agreement between the analyses by three different laboratories, 

using three different methods, is excellent. These analyses 

allow identification of the following host phases for minor 

elements: terrigenous quartz, clay minerals, and other Al 

silicate minerals (detrital fraction), and biogenic silica, calcite, dolomite, organic matter, and apatite (marine fraction). 

Part of the marine fraction of minor elements also might be 

present as sulfides, but we have no evidence for the presence 

of this phase, except for pyrite.

The current minor-element contents in the marine fraction alone required, at the time of deposition of the sediment 

in these two basins, a moderate level of primary productivity in the photic zone (Cd, Cu, Fe, Mo, Se, Zn) and denitrifying bacterial respiration in the bottom water (Cr, V, and rareearth elements). We interpret the absence of any enrichment 

in Cu, Cd, Se, Mo, and Zn above that provided by accumulating organic matter to preclude the establishment of sulfate reduction in the water column.

INTRODUCTION

The geochemistry of sedimentary formations composed 

of the four units organic-carbon-enriched mudstone, limestone and dolomite, chert and porcellanite, and phosphorite 

have been widely studied because of (1) their oil-source and 

reservoir potential (Waples, 1983), (2) their source of phosphate for fertilizers, and (3) the information that their 

geochemistry might shed on paleoceanography. For example, 

Cook and Shergold (1986) and Donnelley and others (1988) 

suggested that this suite of rocks accumulates during times 

of oceanic anoxia (seawater sulfate reduction), a seawater 

chemistry that may contribute to the preservation of organic 

matter in marine sediment and, ultimately, to the formation

of major oil deposits (Demaison and Moore, 1980; Jenkyns, 

1980; Schlanger and others, 1987).

The Miocene Monterey Formation in southern California, which is both a source rock and a reservoir rock for oil, 

consists of these four units (Bramlette, 1946; Pisciotto and 

Garrison, 1981; Isaacs and others, 1983) and has been interpreted as accumulating in an environment of intermittently 

high primary productivity in the photic zone of the water 

column (Blueford and Isaacs, 1989) and under anoxic conditions in the bottom water (Bramlette, 1946; Govean and 

Garrison, 1981). This interpretation was based largely on 

the occurrence of finely laminated porcellanite and diatomite units in both the lower and upper parts of the formation 

and on the exceptionally high organic-matter contents.

In this study, we examine the chemical composition 

(major-element oxides, organic carbon, and minor elements) 

of the Monterey Formation. The aim of our research is to 

establish criteria, based on minor-element contents, for (1) 

defining the approximate primary productivity in the seawater photic zone and (2) identifying the redox conditions of 

the bottom water at the time of deposition, as opposed to the 

redox conditions of the sediment pore water during early 

diagenesis. Basically, we attempt to determine the source 

phases of minor elements at the time of their deposition, as 

opposed to their current host phases in the rocks. These 

criteria may be applicable to other sedimentary formations. 

The success of determining the seawater chemistry of deposition from the current minor-element contents of a formation, however, depends largely on the degree to which the 

marine fraction of minor elements is diluted by the detrital 

fraction and on the extent to which this marine fraction was 

retained in the sediment during early diagenesis, lithification, 

and deep burial, at one extreme, and subaerial weathering, at 

the other extreme. In the Monterey Formation, the rocks 

consist of a large fraction of marine mineral components, 

suggesting that the marine minor-element signal may not be 

masked by terrigenous debris or erased by postdepositional 

events. That is, the minor-element contents of this formation 

might be interpretable in terms of the environment of deposition, specifically the seawater chemistry.
GEOCHEMISTRY OF MINOR ELEMENTS IN THE MONTEREY FORMATION, CALIFORNIA

Acknowledgments.—We thank S. Calvert, J. Domagalski, and L. Balistrieri for their helpful reviews of the manuscript. M. Medrano drafted many of the figures and tables.

ANALYTICAL PROCEDURES

A total of 22 samples were analyzed, representing splits 

of rock samples distributed for the Cooperative Monterey 

Organic Geochemistry Study. Of these samples, 13 (KG-1 

through KG-13, tables 1, 2) are from the Naples Beach 

section of the Miocene Santa Barbara-Ventura Basin, including 9 samples from the Monterey Formation and 2 

samples from each of the overlying Sisquoc Formation and 

the underlying Rincon Shale; the other samples are from 

stratigraphically equivalent strata of the Lions Head section 

in the Santa Maria Basin (fig. 1). Although we refer to these 

samples collectively, we note that they come from two 

separate basins. Detailed descriptions of individual samples 

and of the regional geologic setting of the two basins were 

given by Isaacs and others (1992).

Analyses of major elements, reported as oxides (table 

1) and referred to subsequently as such, and of minor elements (table 2) were performed by three separate laboratories: the U.S. Geological Survey laboratories in Menlo Park, 

Calif., and Denver, Colo., and the X-Ray Assay Laboratory 

in Don Mills, Ontario, Canada (M, D, and X, respectively, 

tables 1-3). The methods used were X-ray-fluorescence 

(XRF) spectroscopy, inductively coupled plasma (ICP) spectroscopy, and instrumental neutron-activation analysis 

(NAA). Although details of these methods vary between the 

laboratories, the basic techniques are quite similar in all 

three laboratories, and all use internationally accepted rock 

standards for calibration. Complete descriptions of the procedures used at laboratories D and M were given by 

Baedecker (1987).

Agreement between the different techniques used at the 

three laboratories for major-element-oxide analyses is excellent (table 3); for example, for Fe, the agreement is within 

3 percent (fig. 2A), and correlation coefficients are greater 

than 0.985. Correlation coefficients for 93 of the 101 pairs 

of analyses exceed 0.98. We elected to use the XRF analyses 

for major-element oxides (tables 1-3) from laboratory D 

(analyses D-XRF, fig. 2A).

Rather than discuss the precision and accuracy for each 

minor element, we use the data for Cr (fig. 2B) and Ba (fig. 

2Q to establish the confidence level of the minor-element 

analyses and to identify possible analytical problems. Our 

reasons for selecting Cr are that we have four analyses of 

each sample and Cr is an element that we discuss below 

in some detail. The X-NAA and X-ICP analyses agree 

closely about the 1-to-l line. The D-ICP analyses are uniformly higher than the X-NAA and X-ICP analyses, but 

they otherwise correlate strongly with both sets of analyses; 

that is, they have a high precision (table 4). This variation

likely results from a systematic bias, rather than from a 

failure of the analytical methods in either laboratory, given 

the excellent agreement between the X-NAA and X-ICP 

analyses. Still, the disagreement is not insignificant and 

needs to be resolved. The deviation of the X-XRF analyses 

from both the X-ICP and X-NAA analyses cannot be explained in this way because all three analyses are from the 

same laboratory. The agreement between the ICP and NAA 

analyses suggests that both methods give superior results for 

Cr. The XRF analyses for other minor elements may be 

equally reliable, or even superior, to the NAA and ICP 

analyses; we simply have not examined the XRF technique 

thoroughly.

Incomplete dissolution of minor minerals, such as rutile 

and sphene, can introduce serious analytical errors into the 

ICP analyses (Gromet and others, 1984; Sholkovitz, 1990). 

These minerals are extremely difficult to dissolve with the 

acids used in conjunction with the ICP procedure. This 

condition may have greatly affected the ICP analyses for Ba 

in this study (fig. 2Q. In sample KG-24 (table 2), the Ba 

content is 2,500 ppm by NAA and only 61 ppm by ICP 

analysis; the difference corresponds to a possible barite 

content of about 0.40 weight percent, a mineral that also is 

highly insoluble.

This problem might have biased the rare-earth-element 

(REE) analyses, as well as the Ba analyses. Marine barite is 

known to have exceptionally high REE contents (Guichard 

and others, 1979). For example, in sample KG-24, the La 

content by ICP analysis is 7.2 ppm (31 percent) lower than 

by NAA analysis (table 2). If this discrepancy is a result of 

incomplete dissolution of barite in the ICP procedure, then 

the barite in this sample also has extremely high REE contents. As discussed below, the REE pattern of sample KG24 lends some support to this interpretation. The Ba contents 

of other samples are much less than that of sample KG-24, 

and although there is a disagreement between the NAA and 

ICP analyses for Ba, for La the two procedures show no 

consistent differences (table 2).

Therefore, we elected to use the X-NAA analyses because this technique measures the bulk concentration of an 

element without resorting to chemical pretreatment, similar 

to the XRF technique. For those minor elements not measured by NAA, we used the X-ICP analyses. Agreement 

between the X-ICP and D-ICP analyses for these minor 

elements, an agreement not seen in the Ba analyses (fig. 2Q, 

supports the interpretation that the data are not biased by 

incomplete dissolution of barite or other weakly soluble 

minerals.

REVIEW: ELEMENTAL SOURCES— 

THE MODERN OCEAN

Marine sediment is a complex mixture of detrital debris 

and seawater-derived material (Goldberg, 1963a). The
Table 1. Major-element-oxide contents in the Monterey Formation.

[All values in weight percent. LOI, loss on ignition; TOC, total organic carbon; dashes, not analyzed. Laboratories: D, U.S. Geological Surve

U.S. Geological Survey, Menlo Park, Calif.; X, X-Ray Assay Laboratory, Eton Mills, Ontario, Canada. TOC and sulfur were determined in la

only by number (#). Methods: ICP, inductively coupled plasma spectroscopy; NAA, instrumental neutron-activation analysis; XRF, X-ray-fluore

Sample (fig. 1) ———

Laboratorymethod

SiO2 — X-XRF

SiO2 — D-XRF

SiO2 — M-XRF

AhOj- X-ICP

Al203- X-XRF

AhOs- D-XRF

AhO}-- M-XRF

A1203- D-ICP

Fe2O3~ D-ICP

Fe2O3- X-NAA

Fe2O3~ X-ICP

Fe2O3~ X-XRF

Fe2O3-- D-XRF

Fe2O3- M-XRF

CaO— X-NAA

CaO— X-ICP

CaO — X-XRF

CaO— D-XRF

CaO — M-XRF

CaO — D-ICP

MgO~- X-ICP

MgO — X-XRF

MgO~- D-XRF

MgO — M-XRF

MgO — D-ICP

Na2O-~ X-NAA

Na20-~ X-ICP

Na_O~ X-XRF

Na.0--- D-XRF

Na2O~ M-XRF

Na2O~ D-ICP

K2O — X-ICP

K2O — X-XRF

K2O — D-XRF

K2O— M-XRF

K_O — D-ICP

P2O5 — X-ICP

P&S — X-XRF

P2O5 — D-XRF

P2O5— - M-XRF

P2O5 — D-ICP

TiO2 — X-ICP

TiO2— X-XRF

TiO2 — D-XRF

TiO2 — M-XRF

TiO2 — D-ICP

MnO — X-XRF

MnO— - D-XRF

MnO — M-XRF 

LOI

LOI

LQJ ____ _______

Total- X-XRF

TOC — #26

TOC— - #15

TOC— - #36

§ ___ ^15

KG-l

„

23.3

23.3

6.44

—

5.70

6.0

6.24

2.33

2.12

2.14

—

2.16

2.3

22.4

25.3

—

24.9

25.4

24.3

.91

~

.94

85

.96

1.62

2.00 —

1.45

1.6

1.94

1.46 —

1.07

1.24

1.55

2.29

_

2.37

3.24

2.61

.28

—

.25

.26

.25

__

<.02

<.02

34.3

33^8

10.02

9.61

10.26

2.47

KG-2

29.4

28.4

28.2

6.75

6.81

6.26

6.5

6.44

2.33

2.17

2.23

2.39

2.29

2.4

12.5

14.6

14.7

14.1

14.5

13.5

1.29

1.47

1.32

1.2

1.28

1.48

1.82

1.30

1.43

1.5

1.75

1.18

1.08

.96

1.08

1.20

3.55

3.22

3.70

4.36

3.87

.33

.34

.31

.34

.28

02

<.02

.02 

39.1

39.1

38.4

99.88

15.90

15.71

16.81

3.05

KG-J

45.7

45.1

45.7

12.30

11.9

11.5

11.8

11.49

5.23

4.72

5.36

5.37

5.29

5.4

4.8

7.2

6.63

6.56

6.54

6.3

3.02

2.89

2.80

2.8

2.72

1.35

1.62

1.57

1.45

1.4

1.63

2.53

2.49

2.33

2.38

2.46

3.02

2.47

3.04

3.84

3.09

.63

.61

.59

.62

.55

.04

.03

.04 

20.5

20.6

200

100.20

6.51

6.16

6.65

1.86

KG-4

40.2

39.9

40.3

9.90

10.6

9.94

10.0

9.64

3.35

3.07

3.33

3.41

3.34

3.5

2.9

3.7

3.65

3.53

3.62

3.4

1.41

1.46

1.40

1.4

1.33

1.75

1.97

1.86

1.81

1.9

1.94

1.75

1.93

1.66

1.74

1.71

.92

.81

.97

.98

.99

.53

.55

.50

.54

.43

.03

<.02

.03 

35.9

36.3

35.9

100.46

16.40

16.25

17.28

3.06

KG-5

60.8

57.6

57.7

6.88

7.08

6.50

6.7

6.78

2.53

2.26

2.37

2.32

2.37

2.4

7.3

8.4

8.56

8.01

7.86

8.0

1.11

1.74

1.11

1.0

1.14

1.62

1.98

1.54

1.73

1.9

2.06

1.24

1.32

1.14

1.14

1.30

.76

.62

.78

.70

.85

.37

40

.32

14

.32

<01

<.02

<.02

1-1 Q

IJ.O

20.1

22.2

98.20

3.33

3.04

3.30

1.23

KG-6

50.5

50.3

50.4

11.64

12.0

11.6

11.7

11.39

4.17

3.89

4.10

4.18

4.16

4.3

3.2

4.2

4.12

4.04

4.04

4.0

1.64

1.69

1.64

1.6

1.59

2.16

2.51

2.28

2.14

2.3

2.33

2.05

2.18

1.98

2.02

2.06

.73

.60

.72

.68

.73

.60

.61

.58

.62

.52

.03

<.02

.03 

21.7

22.4

19.0

99.92

5.50

5.31

4.90

1.76

KG-7

67.5

66.9

67.8

8.62

9.23

8.81

8.9

8.67

2.73

2.53

2.57

2.58

2.63

2.7

1.1

1.0

1.08

1.07

1.06

1.1

1.06

1.09

1.07

1.1

1.04

2.02

2.08

2.21

1.89

2.1

2.08

1.78

1.89

1.75

1.76

1.81

.30

.26

.32

.28

.32

.45

.46

43

.48

.38

.03

<.02

.02 

13.2

14.1

13.9

99.55

3.97

3.72

4.03

.91

KG-8

51.9

51.0

50.9

9.81

11.6

11.0

11.1

10.73

4.13

4.02

3.87

4.18

4.14

4.3

2.4

3.0

3.18

3.12

3.12

3.0

1.69

1.75

1.70

1.7

1.62

2.16

2.36

2.42

2.18

2.3

2.36

2.00

2.20

1.97

1.98

2.02

.99

.82

1.00

.96

1.01

.58

.60

.57

.60

.50

.04

.03

.04 

21.4

22.4

22.4

100.12

5.79

5.82

5.81

1.50

KG-9

47.2

46.9

47.0

12.45

12.9

12.5

12.7

12.64

5.39

5.26

5.02

5.40

5.37

5.5

5.9

7.1

7.09

7.15

7.06

6.9

3.57

3.56

3.52

3.5

3.38

1.62

1.85

1.75

1.65

1.8

1.87

2.72

2.83

2.63

2.68

2.81

1.70

1.37

1.71

2.60

1.74

.70

.70

.70

.72

.63

.04

.03

.04 

17.4

17.3

16.7

100.28

4.12

3.94

4.19

1.31

KG-10

39.9

39.5

39.8

5.56

5.80

5.44

5.7

5.93

2.30

2.27

1.%

2.21

2.17

2.3

18.2

19.6

20.6

20.7

20.7

20.1

1.76

2.00

1.87

1.8

1.91

1.27

1.48

1.16

1.17

1.3

1.51

1.35

1.32

1.23

1.28

1.51

.44

37

.43

.36

.46

.28

.29

.27

.28

.27

.02

<.02

.02 

25.6

26.2

25.9

99.29

4.15

3.88

4.15

.98

KG-11

57.6

57.3

57.7

3.44

3.51

3.28

3.4

3.55

1.39

1.30

1.17

1.36

1.26

1.3

12.7

14.7

15.8

15.1

15.0

15.5

.99

1.17

1.07

1.0

1.11

.93

1.12

1.05

.86

1.0

1.13

.77

.87

.72

.74

.87

.21

.18

.22

.18

.23

.17

.18

.15

.18

.15

.02

<.02

<.02

10 e

lo.j

19.0

18.3

1007.5

2.57

2.40

2.57

.59

KG-12

64.6

64.0

65.1

10.15

10.6

10.2

10.2

10.17

4.15

3.76

3.99

3.98

3.99

4.0

1.7

1.4

1.39

1.36

1.36

1.4

1.66

1.65

1.64

1.6

1.62

2.02

2.22

2.37

2.06

2.2

2.28

1.63

1.75

1.59

1.58

1.66

.41

.33

.41

.38

.44

.52

.52

.48

.52

.45

.03

<.02

.03 

12.2

13.2

12.7

9944

.89

.87

.,

.41

KG-13

66.4

64.5

65.4

8.94

9.63

9.14

9.2

9.01

3.56

3.12

3.27

3.72

3.43

3.5

.7

.9

.85

.86

.86

.9

1.39

1.44

1.41

1.4

1.38

1.75

1.86

1.93

1.75

1.9

1.90

1.39

1.53

1.37

1.38

1.42

.27

.25

.28

.26

.30

.47

.52

44

.48

.40

.03

<.02

.02 

14.5

16.1

15.7

100.83

.89

.86

.91

.56

KG-14

56.2

55.5

55.9

11.30

11.1

10.7

10.7

10.73

4.03

3.95

3.85

4.05

4.02

4.1

6.2

7.1

6.98

6.93

6.82

6.7

2.50

2.45

2.43

2.3

2.34

1.89

2.00

1.%

1.80

1.9

2.00

2.41

2.43

2.28

2.30

2.41

.44

.33

.41

.36

.41

.55

.55

.53

.54

.45

.04

.03

.04 

13.4

13.5

11.6

99.51

2.35

2.22

2.30

3.61

KG-15

58.1

57.1

57.6

7.27

7.37

6.98

7.2

7.37

2.86

2.56

2.50

2.79

2.73

2.8

8.7

9.8

10.5

10.1

9.92

10.1

2.11

2.20

2.12

2.0

2.16

1.35

1.48

1.51

1.35

1.5

1.62

1.34

1.40

1.29

1.30

1.45

.44

.42

.51

.44

.55

.33

.34

.32

.34

.25

.03

<.02

.04 

15.1

15.6

14.6

99.79

3.92

3.71

3.78

1.29

KG-16

33.5

32.6

32.7

4.63

4.69

4.41

4.6

4.91

1.80

1.74

1.43

1.71

1.66

1.7

15.4

15.5

17.1

16.9

17.1

16.9

9.42

9.85

9.53

9.4

9.02

.42

.67

.46

.42

.6

.53

1.19

1.29

1.13

1.18

1.35

.92

.91

1.06

.96

1.17

.23

.24

.21

.24

.22

.02

<.02

.03

OQ O

ZO.7

28.6

28.9

98.69

5.60

5.12

5.67

2.35

KG-17

43.2

42.5

43.0

3.85

3.73

3.52

3.7

3.70

1.77

1.66

1.59

1.73

1.69

1.7

18.2

21.4

21.7

21.4

21.4

20.7

.48

.71

.53

0.45

.55

.47

.50

.50

.40

.5

.57

.99

1.02

.91

.92

1.01

3.60

3.12

3.76

4.72

4.03

.23

.23

.21

.22

.20

<.01

<.02

<.02 

23.0

23.1

21.0

98.%

6.85

6.63

—

3.01

KG-18

24.2

23.8

23.0

3.67

3.75

3.51

3.5

3.93

3.19

2.93

2.44

3.11

2.98

3.2

21.0

20.1

22.6

22.7

23.2

22.7

11.59

12.20

12.0

11.4

11.26

.63

.82

.53

.58

.8

.80

.76

.64

.65

.76

.87

.18

.19

.21

.16

.25

.17

.19

.16

.18

.15

.14

.13

.16 

30.5

31.2

30.9

98.05

.90

.72

.80

1.17

KG-1

3.69

3.61

3.13

.57

.40

.37

.41

.42

.17

.16

.13

.17

.10

.09

28.0

27.1

29.7

30.2

31.6

30.2

19.57

20.90

20.0

194

17.08

.07

.23

.10

<.15

.2

.08

.12

.07

.05

.04

.08

.25

.26

.28

.22

.32

.02

.03

<.02

.02

.01

<.01

<.02

<.02

A1 8

•rj.o 

44.7

46.6

99.12

.93

2.17

.73

.15
Table 2. Minor-element contents in the Monterey Formation.

[All values in parts per million. Dash, not analyzed. Laboratories: D, U.S. Geological Survey, Denver, Colo.; X, X-Ray Assay Laboratory, Don Mills, O

inductively coupled plasma spectroscopy; NAA, instrumental neutron-activation analysis; XRF, X-ray-fluorescence spectroscopy]

Sample (fig. 1)— — KG-1

Laboratorymethod

Ag-~~

y^g ____

Ba— ~

Ba— — -

Ba— — -

ge _____

Br— — -

Cd-~ —

(2$ __

Ce- —— -

Ce — —

Co— —

Co— —

Co —— -

Cr— ~

Cr- — -

Cr — —

Cr- —— -

Cs — —

Cu——

Cu——

Eu— — -

Calif———

La— —

La —— ~

Li— -----

Li ———

Lu — —

Mo ——

Mo— —

Mo — -

Nd- —

Nd——

Ni-~ —

Ni- — -

Rb— —

Sb— —

Sc- ——

Sc- — -

Sc- —— -

Se —— -

Sm ——

Sr ——

Sr ———

Th~ — -

U— — -

y ___

y ___

Y __._.

Y ___

Yb ——

Zr~ —

Zn— — -

Zn- ——

2-j _____

X-ICP

X MA A

X-NAA

X-ICP

D-ICP

X-ICP

X-NAA

X-ICP

D-ICP

D-ICP

X-NAA

X-NAA

X-ICP

D-ICP

X-NAA

X-ICP

X-XRF

D-ICP

X-NAA

X-ICP

D-ICP

X-NAA

D-ICP

X-NAA

X-NAA

D-ICP

X-ICP

D-ICP

X-NAA

X-NAA

X-ICP

D-ICP

X-NAA

D-ICP

X-ICP

D-ICP

X-NAA

X-NAA

X-NAA

X-ICP

D-ICP

X-NAA

X-NAA

X-ICP

D-ICP

X-NAA

X-NAA

X-ICP

D-ICP

X-ICP

D-ICP

X-NAA

X-ICP

X-NAA

X-ICP

D-ICP

1.4

12

1,000

654

80

4.7

73

8

8

18

20

7

5

7

220

209 —

309

3

85.4

93

.4

8

1.5

13.9

16

16

17

.14

40

47

58

9

11

156

197

50

3.0

4.5

4.3

5

24

2.0

772

947

4.1

12.3

204

212

15.9

19

1.0

40.7

170

181

1%

KG-2

2.4

12

1,100

246

52

4.7

100

8

8

19

22

9

5

7

320

315

369

428

3

91.1

98

.4

8

1.5

15.8

17

20

21

.22

17

26

31

11

12

240

283

50

8.0

6.4

6.1

7

35

2.3

605

708

4.4

15.6

357

370

22.5

26

1.5

39.1

240

267

281

KG-3

1.0

22

500

383

86

5.4

13

32

28

37

39

12

11

13

200

215

231

264

6

47.0

47

.5

16

2.5

23.6

25

52

55

.25

33

49

55

18

20

114

127

80

1.4

12.2

12.6

13

13

3.5

385

423

6.7

22.5

180

172

25.6

28

1.8

50.0

190

237

222

KG-4

1.8

16

500

450

42

4.8

78

12

11

36

38

11

7

9

300

292

398

410

4

115.0

116

.7

13

2.5

26.0

25

34

34

.31

26

36

41

18

23

261

271

50

9.6

9.1

8.9

9

45

3.7

231

257

7.1

22.4

417

407

27.9

32

2.1

34.1

280

313

304

KG-5

0.9

5

400

332

358

3.9

54

3

3

28

29

7

5

7

90

89

112

120

4

31.5

33

.5

9

1.3

16.5

18

19

20

.17

8

13

16

13

13

57

73

50

3.6

6.3

6.2

7

6

2.2

333

388

4.7

8.4

156

157

12.8

14

1.1

28.7

90

85.3

84

KG-6

0.4

9

500

401

109

5.2

55

3

3

44

49

11

9

10

140

137

174

173

5

52.9

55

.8

15

3.1

27.8

27

39

38

.29

15

20

25

20

23

94

105

80

3.9

9.5

9.0

10

9

3.9

245

277

8.8

12.3

253

248

19.7

22

1.9

75.9

120

157

144

KG-7

0.6

7

500

326

309

3.6

41

5

4

35

39

8

6

7

120

104

143

138

5

35.9

37

.6

11

2.6

23.3

22

23

22

.27

12

18

20

17

19

80

97

70

2.7

7.8

7.0

8

9

3.2

128

149

6.9

13.7

213

214

16.3

19

1.6

29.0

110

101

103

KG-8

1.1

Q

700

504

66

4.7

51

8

8

40

50

12

8

11

170

145

203

1%

4

55.3

56

.7

14

2.9

25.9

24

32

34

.30

19

20

27

21

20

129

152

60

5.3

10.5

9.3

11

13

3.8

209

246

8.9

16.9

260

264

17.6

21

1.9

47.0

130

152

153

KG-9

0.5

13

500

369

396

5.4

15

1

<2

42

43

14

13

15

250

232

282

333

8

39.0

40

.8

17

2.6

28.0

31

40

48

.36

8

7

11

20

24

116

132

100

1.5

15.6

13.8

16

5

4.0

311

367

7.8

14.3

130

138

30.9

37

2.2

53.5

160

173

175

KG-10

1.0

10

400

356

441

4.5

28

11

12

18

18

8

5

9

130

102

111

155

3

33.6

35

.8

8

1.6

12.0

14

9

14

.23

15

16

22

9

9

91

121

40

2.3

8.1

7.0

9

6

1.9

594

757

3.3

7.1

180

199

13.7

17

1.6

59.9

130

117

135

KG-11

0.6

6

200

168

199

3.1

19

7

8

10

11

5

3

6

77

65

68

97

3

21.7

21

.2

5

.9

7.2

9

6

7

.12

13

10

17

5

5

56

78

<20

1.3

4.7

4.2

5

3

1.1

451

572

2.1

3.9

113

126

7.9

9

.7

78.9

70

70

78

KG-12

0.4

7

400

422

297

4.1

26

2

<2

33

38

7

5

8

99

74

122

112

3

17.3

18

.8

12

3.3

18.6

19

31

31

.20

5

4

6

15

18

38

49

40

1.0

9.5

9.1

10

<3

2.8

157

181

5.9

4.7

95

95

12.6

14

1.2

41.4

60

77.1

71

KG-1 3

0.6

6

400

320

323

2.9

25

1

<2

28

27

7

7

7

83

69

171

104

3

16.3

16

.4

11

2.3

15.4

16

29

29

.17

<5

3

5

12

14

40

49

50

.8

8.9

8.5

9

<3

2.3

120

137

4.7

3.4

90

91

10.3

11

1.0

38.5

40

73.1

65

KG-14

0.7

7

500

404

49

4.2

7

3

3

32

37

11

8

11

140

115

143

143

4

32.8

32

.8

14

3.4

2.6

20

14

10

.30

8

10

11

17

18

74

92

80

2.2

12.1

10.8

12

5

3.5

194

214

5.8

4.5

161

159

18.6

20

2.0

44.7

100

112

108

KG-1 5

1.1

7

400

304

343

3.2

7

8

8

19

21

7

6

8

160

128

205

178

3

38.3

40

.7

9

2.1

12.9

14

16

20

.20

24

28

32

10

11

89

123

40

3.1

7.5

6.7

8

13

2.1

251

301

3.7

4.9

262

274

13.4

15

1.2

25.7

90

116

134

KG-16

1.3

10

500

301

270

3.8

6

16

16

20

25

6

4

6

130

117

126

177

2

46.4

53

.5

8

1.3

14.9

16

8

12

.19

21

27

33

12

12

87

125

30

5.1

4.9

3.8

5

17

2.2

154

203

4.2

14.1

290

340

13.0

16

1.2

78.6

190

161

191

KG-17

1.5

12

400

280

132

4.1

8

6

6

11

16

5

4

6

140

144

132

195

1

58.8

60

.5

5

1.5

12.0

14

9

9

.24

17

22

26

12

10

135

178

20

8.2

5.1

4.8

5

20

2.0

512

594

1.9

13.5

278

290

20.1

23

1.6

19.4

180

163

186

KG-1 8

0.3

2

400

275

369

3.3

6

<1

<2

13

12

4

3

5

47

38

26

57

2

14.4

13

.3

6

1.3

7.8

9

5

7

.12

<5

5

9

5

5

18

37

20

.8

4.2

3.3

4

<3

1.1

248

338

2

4.1

56

70

6.3

7

.6

51.3

60

38.9

30
REVIEW: ELEMENTAL SOURCES—THE MODERN OCEAN

NAPLES BEACH SECTION

Age (Ma)

-5.1-

SISQUOC 

FORMATION

LEGEND

NAPLES BEACH SECTION

-5.5-

-7.0-

-8.4-

-8.9-

-14.0-

-15.0-

-17.8-

O 

P

£

> 

w

O

s

Clayeysiliceous 

member

Upper calcareoussiliceous and 

transitional 

marl-siliceous 

members

Carbonaceous 

marl

member

Lower 

calcareoussiliceous 

member

RINCON 

SHALE

=&=v==O=J Diatomaceovu mudstone and shale 

Tj^i^jajuuijini Porcelanite and mudstone

Calcareous diatomaceoiu mudstone 

and shale with interbedded porcelanite

l=—Z-=^—£ Phosphatic shale 

•r;=0=T-:=-,-= Calcareous diatomaceoiu mudstone and shale

Calcareous mudstone, shale, 

and porcelanile

Porcelanite and calcareous shale 

with intcrbedded dolomite

LIONS HEAD SECTION

SCALE 

FEET

r-200

50-

L 0

O

H

O

W

g

O

s

JD

e

a

T3

§

JD 

g

1

O

Point Sal

Age (Ma) 

h>8.9 -i

-11.4-

1-15.6-J

ophiolite

Figure 1. Stratigraphic sections of the Monterey Formation at Naples Beach (Santa Barbara-Ventura Basin) and Lions Head (Santa Maria 

Basin), Calif., showing locations of samples. Ages compiled from Arends and Blake (1986), Barton (1986), and DePaolo and Finger 

(1991). Stratigraphic positions revised from Isaacs and others (1992); Point Sal ophiolite from Hopson and Frano (1977).
GEOCHEMISTRY OF MINOR ELEMENTS IN THE MONTEREY FORMATION, CALIFORNIA

detrital fraction consists mostly of terrigenous Al silicates 

and quartz, introduced into the oceans by way of riverine 

and eolian transport, and marine volcaniclastic debris. The 

seawater-derived marine fraction is predominantly inorganic

z u

W 06

H H

Z CU

O H

U g

f>O O «

ciWo> >. fe ^

EXPLANATION

o Fe (D-ICP)

• Fe (X-NAA)

a Fe (X-XRF)

x Fe (X-ICP)

+ Fe (M-XRF)

23456

Fe2O3 CONTENT, 

IN WEIGHT PERCENT (D-XRF)

600

z

o

3

SH 400

500

HfiC 

ZW 300 00-

200 

Z TOO

EXPLANATION

• Cr (X-NAA)

a Cr (X-XRF)

o, Cr (D-ICP)

0 100 200 300 400 500 

Cr CONTENT, IN PARTS PER MILLION (X-ICP)

700

Z 600

O

,j 500

400

300

200

S 100

z

EXPLANATION 

x Ba (X-ICP) 

o Ba (D-ICP)

0 500 1000 1500 2000 2500 3000 

Ba CONTENT, IN PARTS PER MILLION (X-NAA)

Figure 2. Intraelement ratios for Fe2O3 (A), Cr (fi), and Ba (Q. 

Analyses are identified by laboratory (D, U.S. Geological Survey, 

Denver, Colo.; M, U.S. Geological Survey, Menlo Park Calif.; X, 

X-Ray Assay Laboratory, Don Mills, Ontario, Canada) and method 

(ICP, inductively coupled plasma spectroscopy; NAA, instrumental 

neutron-activation analysis; XRF, X-ray-fluorescence spectroscopy).

precipitates and adsorbates (hydrogenous fraction) and 

CaCO3 , opal, and organic debris (biogenic fraction). The 

distribution and abundance of the detrital and marine fractions, their composition and rates of accumulation, and their 

alteration products vary widely within the oceans. Geochemists have used the complex distributions and major-elementoxide and minor-element compositions of these fractions 

to identify the past record of such phenomena as eolian 

transport of terrigenous material, biologic productivity in 

the photic zone, hydrothermal activity along midoceanic 

ridges, and sediment diagenesis as it might relate to 

metallogenesis.

An evaluation of the geochemistry of ancient depositional environments for marine sedimentary rocks must be 

based on the major-element-oxide and minor-element compositions of their marine fractions alone. For major-element 

oxides, the marine signal is commonly masked by the detrital fraction, even in sediment for which the accumulation 

rate of detrital debris is low. In modern sediment from the 

central Pacific Ocean, where the accumulation rate is as low 

as 0.1 mg/cm2 per year, the ratio of the marine to detrital 

fraction of Fe is approximately 0.05 to 0.10 (Piper, 1988), 

ferromanganese nodules aside. By contrast, this ratio is as 

high as 2 to 10 for many minor elements in pelagic sediment 

(Chester and Hughes, 1967; Fischer and others, 1986; Piper, 

1988). In sediment from ocean-margin areas, however, where 

accumulation rates are as much as 105 times higher, the 

marine fraction of minor elements also can be masked by the 

detrital fraction, making identification of the marine fraction 

uncertain, if not impossible.

Two procedures are commonly used to partition minor 

elements among the different sedimentary fractions. One 

procedure uses a chemical leaching procedure (Chester and 

Hughes, 1967; Bruland and others, 1974; Bowser and others, 1979; Lyle and others, 1984; Tessier and others, 1984; 

Boust and others, 1988); the other involves modeling the 

sediment on the basis of end-member compositions of the 

major fractions (Leinen, 1977; Isaacs, 1980; Dymond, 1981; 

Calvert and Price, 1983; Isaacs and others, 1983; Medrano 

and Piper, 1992)—a stoichiometric approach—or on the 

basis of factor analysis or other similar statistical approaches.

Both the leaching and modeling procedures are not 

without problems. For the leaching procedure, sample treatment can introduce a bias (Belzile and others, 1989; 

Sholkovitz, 1990; Tessier and Campbell, 1991; Piper and 

Wandless, 1992). Among the problems are incomplete isolation of a fraction at any single step of the procedure, which 

then imposes an operational rather than genetic interpretation on the origin of the varyingly soluble fractions. For the 

modeling procedure, a major uncertainty can be introduced 

by selecting a single end-member composition for each of 

the different fractions (Leinen and Pisias, 1984). Multiple 

and varying detrital sources (Bostrom and others, 1969; 

Calvert, 1990), as well as marine sources, can impart a 

complex chemistry to both the detrital and marine fractions.
REVIEW: ELEMENTAL SOURCES—THE MODERN OCEAN

Despite these and other problems, both procedures have 

been used with some success (Chester and Hughes, 1967; 

Bruland and others, 1974; Dymond, 1981; Isaacs and others, 

1983; Leinen and Pisias, 1984; Tessier and others, 1984; 

Piper, 1988; Belzile and others, 1989; Calvert, 1990). We 

use a modeling procedure in this study, although the leaching procedure might be the only way to collect information 

about the marine fraction of the several minor elements 

whose bulk contents are strongly dominated by the detrital 

contribution.

DETRITAL SOURCE

Studies using a stoichiometric, or normative, scheme to 

evaluate the detrital input of elements to the marine environment typically use A12O3 to estimate the abundance of the 

detrital fraction (Isaacs, 1980; Dymond, 1981; Leinen and 

Pisias, 1984; Medrano and Piper, 1992). Implicit in the 

calculations is the assumption that the sum of the components of the detrital fraction (quartz, feldspar, clay minerals, 

and other Al silicate minerals) has a constant major-element-oxide and minor-element content (table 5), that is, that 

the interelemental ratios with A12O3 are constant between 

samples, which is clearly a more reasonable assumption for 

any single formation than it is for formations separated both 

temporally and areally.

The detrital contribution of SiO2 P2O5 , MgO, and CaO 

to each sample is calculated on the basis of their ratios to 

A12O3 in a standard. The standard most often referenced is 

the World Shale Average (WSA; Wedepohl, 1969-78). The 

major-element-oxide contents in excess of the detrital contribution then give the amounts of biogenic silica, apatite, 

dolomite, and calcite (also adjusted for CaO content in 

apatite and dolomite) by using appropriate stoichiometric 

factors. The determination of organic-carbon content gives 

the abundance of organic matter present (table 6). The 

K2O:A12O3 and TiO2 :Al2O3 ratios can evaluate the degree 

to which the selected composition of WSA is representative 

of the detrital fraction because K2O and TiO2, along with 

A12O3 occur virtually totally in the detrital fraction of many, 

though certainly not all, sedimentary rocks.

The same procedure determines the contribution of 

minor elements by the detrital fraction. That is, minorelement:detritus ratios are assumed to be constant and similar to those in the WSA, or another, standard. In this study, 

we used the REE contents of the North American Shale 

Composite (NASC; Gromet and others, 1984), except for 

Ce. The contents of other minor elements in detritus (table 

5) are from Wedepohl (1969-78). Previous studies have 

shown that Co:Al2O3 , Ga:Al2O3 , Li:Al2O3 Sc:Al2O3 , and 

Th:Al2O3 ratios may be used to evaluate this procedure for 

the minor elements (Piper, 1991; Dean and Arthur, 1992) 

because they, like I^O and TiO2, are present predominantly 

in this fraction.

MARINE SOURCE

Within the modern open ocean, the bulk of the marine 

fraction of Cu, Cd, Se, Zn, and, possibly, Cr, Mo, and V 

accumulating in the sediment may be transported to the sea 

floor by organic debris, whose minor-element stoichiometry 

(table 5) has been estimated from field studies (Martin and 

Knauer, 1973; Bruland, 1983; Collier and Edmond, 1984; 

Brumsack, 1986). Organic matter is most important to minor-element budgets in shelf-slope environments (Collier 

and Edmond, 1984), which have high rates of accumulation 

of organic matter.

In addition to organic matter, biogenic silica and calcite 

contribute to the marine flux of minor elements to the sea 

floor. Silica may be an important carrier of Ni (Sclater and 

others, 1976) and Zn (Bruland, 1983), and its content of Cu, 

on the basis of the analyses by Martin and Knauer (1973), is 

slightly higher than that of Zn. Conversely, biogenic carbonate contributes little to the minor-element contents of sediment other than Sr (Palmer, 1985). If the biochemical 

pathways of minor elements in ancient oceans were similar 

to those in the modern ocean, organic debris would have 

provided a major flux of several minor elements to ancient 

marine sediment.

Many minor elements in sediment have a marine hydrogenous source, as well as a biogenic source. Under oxic 

seawater conditions, such elements as Fe and Mn and, less 

so, REE's, Co, Cu, Ni, and Zn are transported to the sea 

floor as hydroxides and oxides or as adsorbates on other 

particulates. Under sulfate-reducing conditions, Fe, Cd, Cu, 

and Zn precipitate as sulfides. Cr, Mo, and Se precipitate, or 

are adsorbed onto other particulate matter, owing to their 

reduction to less soluble valence states. Under intermediate 

redox conditions of denitrification, Cr and REE's are extracted from sea-water, either by precipitation or adsorption. 

The accumulation of U and V requires some special attention because their distributions in the natural environment 

seem to conflict with their behavior as predicted by their 

thermodynamic properties.

Thus, the accumulation of minor elements within the 

marine fraction of sediment may reflect the level of primary 

productivity in the photic zone, assuming a stoichiometry 

for the biogenic fraction of minor elements preserved in the 

sediment. The suite of minor elements that show an enrichment in excess of that due solely to the rain rate of organic 

matter onto the sea floor defines the redox conditions of 

bottom water under which the sediment accumulates.

BIOGENIC SOURCE

The minor-element contents of modern plankton have 

been measured by several researchers. Measurements vary 

considerably (Martin and Knauer, 1973; Collier and Edmond, 

1984), owing to inconsistencies introduced during sample
Table 3. Correlation coefficients for major-element oxides in the Monterey Formation.

[All values rounded to nearest hundredth. LOI, loss on ignition; TOC, total organic carbon. Laboratories: D, U.S. Geological Survey, Denver, Colo.; M, U.S. Geo

Ray Assay Laboratory, Don Mills, Ontario, Canada. TOC was determined in laboratories identified only by number (#). Methods: ICP, inductively coupled p

neutron-activation analysis; XRF, X-ray-fluorescence spectroscopy]

Laboratorymethod

SiO2- — X-XRF 

SiO2- — D-XRF 

SiO2- — M-XRF 

A1203— X-ICP 

A12O3— X-XRF 

A1203— D-XRF 

A12O3— M-XRF 

A12O3— D-ICP 

Fe2O3— D-ICP 

Fe2O3— X-NAA 

Fe203— X-ICP 

Fe2O3— X-XRF 

Fe203— D-XRF 

Fe2O3— M-XRF 

CaO— — X-NAA 

CaO- —— X-ICP 

CaO--— X-XRF 

CaO —— D-XRF 

CaO-—— M-XRF 

CaO —— D-ICP 

MgO— - X-ICP 

MgO— - X-XRF 

MgO — - D-XRF 

MgO— - M-XRF 

MgO — - D-ICP 

Na2O— - X-NAA 

Na2O— - X-ICP 

Na2O— - X-XRF 

Na2O — D-XRF 

Na2O— - M-XRF 

Na20— - D-ICP 

K2O— - X-ICP 

K2O- — X-XRF 

K2O — - D-XRF 

K2O— - M-XRF 

K2O — - D-ICP 

P205 — X-ICP 

P205— X-XRF 

P2O5— D-XRF 

P2O5— M-XRF 

PjOs— D-ICP 

TiO2 —— X-ICP 

Ti02 —— X-XRF 

TiO2 —— D-XRF 

TiO2 —— M-XRF 

Ti02 —— D-ICP 

LOI- —— XLOI —— DLOI- —— MTOC— - #26 

TOC—— #15 

TOC—- #36

Si02 

X-XRF

1 

1 

1 

.57 

.59 

.58 

.48 

.59 

.46 

.44 

.46 

.44 

.45 

.44 

-.81

-.80 

-.80

-.81 

-.82

-.80

-.80

-.81 

-.81

-.80 

-.80

.68 

.64

.72

.67 

.68 

.68

.53 

.58

.57 

.54 

.55 

-.18 

-.21 

-.19 

-.19 

-.21 

.57 

.59 

.55

.57 

.55 

-.90

-.88 

-.88

-.09

-.13

-.10

SiO2 SiO2 

D-XRF M-XRF

1 

1 

.58 

.60 

.60 

.48 

.60 

.47 

.46 

.47 

.46 

.46 

.45 

-.81

-.81 

-.80

-.81 

-.82

-.81

-.80

-.81 

-.81

-.80 

-.80

.69 

.64

.73

.68 

.68 

.68

.55

.59

.58

.56 

.56

-.18

-.22 

-.19 

-.19 

-.21 

.58

.60

.57

.58 

.55 

-.90

-.89 

-.88

-.09

-.13

-.09

1 

.58 

.60 

.60 

.48 

.60 

.47 

.46 

.47 

.46 

.46 

.45 

-.81

-.81 

-.80

-.81 

-.82

-.81

-.81

-.81 

-.81

-.81 

-.81

.68 

.63

.72

.67 

.68 

.67

.55

.60

.58

.56 

.56

-.18

-.21

-.19 

-.19 

-.21 

.58

.60

.57

.58 

.55 

-.90

-.89 

-.88

-.08

-.12

-.09

A1203 

X-ICP

1 

.99 

.99 

.89 

.99 

.91 

.91 

.94 

.92 

.92 

.92 

-.84

-.83 

-.84

-.84 

-.84

-.84

-.57

-.60 

-.59

-.58 

-.59

.82 

.82

.85

.84 

.81 

.80

.95

.94

.94

.94 

.93

.25

.20

.22 

.23 

.19 

.98

.98

.98

.98

.97 

-.55

-.57 

-.61

.19

.16

.18

A1203 

X-XRF

1 

1 

.90 

1 

.89 

.89 

.92 

.90 

.90 

.90 

-.87

-.86 

-.87

-.86 

-.86

-.87

-.59

-.61 

-.60

-.60 

-.60

.86 

.85

.89

.87 

.85 

.84

.93

.94

.94

.94 

.93

.22

.16

.19 

.19 

.16 

.99

.99

.99

.99

.98 

-.54

-.56 

-.59

.20

.17

.19

A1203 

D-XRF

1 

.90 

1 

.90 

.90 

.93 

.90 

.91 

.91 

-.86

-.85 

-.86

-.86 

-.86

-.86

-.58

-.60 

-.59

-.58 

-.59

.85 

.84

.88

.87 

.84 

.83

.94

.94

.94

.94 

.93

.21

.16

.18 

.19 

.15 

.99

.99

.99

.99

.98 

-.54

-.57 

-.60

.18

.15

.17

A12O3 

M-XRF

1 

.91 

.79 

.78 

.81 

.79 

.79 

.79 

-.69

-.66 

-.68

-.68 

-.68

-.68

-.46

-.48 

-.48

-.47 

-.47

.84 

.85

.85

.85 

.83 

.84

.76

.76

.76

.76 

.77

.13

.09

.10 

.14 

.09 

.86

.84

.86

.85

.85 

-.52

-.53 

-.56

-.04

-.07

-.03

A1203 

D-ICP

1 

.90 

.90 

.93 

.90 

.91 

.91 

-.85

-.83 

-.84

-.84 

-.84

-.85

-.59

-.61 

-.60

-.59 

-.59

.85 

.84

.87

.86 

.84 

.83

.94

.94

.94

.94 

.94

.22

.16

.19 

.20 

.16 

.99

.98

.99

.99

.98 

-.56

-.59 

-.62

.16

.12

.15

Fe203 

D-ICP

1 

1 

.99

1 

1 

1 

-.70

-.69 

-.70

-.69 

-.70

-.70

-.42

-.44 

-.43

-.43 

-.42

.66 

.66

.69

.68 

.65 

.64

.88

.86

.87 

.86

.21

.15

.18 

.20 

.16 

.88

.90

.91

.90

.88 

-.52

-.56 

-.58

.07

.04

.06

Fe203 

X-NAA

1 

.99 

.99 

1 

1 

-.68

-.68 

-.69

-.68 

-.68

-.68

-.41

-.43 

-.42

-.42 

-.41

.65 

.65

.69

.67 

.64 

.63

.89

.87

.89 

.88

.21

.15

.18 

.20 

.16 

.88

.90

.91

.90

.88 

-.52

-.56 

-.58

.07

.04

.06

Fe203 

X-ICP

1 

.99 

1 

.99

-.74

-.73

-.73 

-.73

-.73

-.44

-.46 

-.45

-.45 

-.44

.69 

.69

.73

.71 

.68 

.67

.90

.89

on

.90 

.88

.26

.20

.23 

.24 

.20 

.91

.93

.94

.93

.91 

-.50

-.53 

-.56

.09

.11

Fe203 

X-XRF

1 

1 

1 

-.70

-.69 

-.70

-.69 

-.69

-.70

-.42

-.44 

-.43

-.42 

-.42

.66 

.65

.69

.67 

.65 

.63

.88

.86

.87

.87 

.86

.23

.18

.20 

.22 

.18 

.88

.90

.91

.91

.88 

-.50

-.54 

-.57

.08

.05

.07

Fe203 

D-XRF

1 

1 

-.70

-.70

-.70

-.70

-.42

-.44 

-.43

-.43 

-.42

.67

.68 

.65 

.64

.89

.87

.88 

.87

.23

.17

.20 

.21 

.17 

.89

.92

.91

.89 

-.51

-.54

.06

.08

Fe203 

M-XRF

1 

-.70

-.70

-.70

-.70

-.42

-.44 

-.43

-.43 

-.42

.66

.68 

.65 

.64

.89

.87

QQ

.88 

.87

.23

.17

.20 

.22 

.18 

.89

.90

.92

.91

.88 

-.50

-.53 

-.56

.10

.07

.09

CaO 

X-NAA

1 

.99 

1 

1 

1 

1 

.72

.73 

.73

.72 

.73

-.84 

-.80

-.85 

-.84 

-.81

-.78

-.82

-.80

-.80

-.77

-.09

-.04

-.06 

-.02 

-.04 

-.85 

-.88

-.84

-.86

-.83 

.62

.62 

.63

-.26

-.23

-.25

CaO 

X-ICP

1 

1 

1 

1 

1 

.67 

.68 

.68 

.67 

.68 

-.82 

-.78 

-.87 

-.84 

-.83 

-.79

-.76 

-.81 

-.79 

-.78 

-.74 

-.03

.02 

-.01 

.03 

.02 

-.84

— 8.7

-.83

-.85

-.81 

.62 

.61 

.63

-.23

-.20

-.22

CaO 

X-XRF

1 

1 

1 

1 

.69 

.70 

.69 

.69 

.70 

-.84 

-.80 

-.88 

-.85 

-.84 

-.80

-.78 

-.82 

-.80 

-.79 

-.76 

-.06

-.02 

-.04 

.00 

-.01 

-.85

— S.S.

-.84

-.86

-.83 

.62 

.61 

.62

-.24

-.22

-.24

CaO 

D-XRF

1 

1 

1 

.70 

.72 

.71 

.71 

.72 

-.84 

-.80 

-.88 

-.85 

-.84 

-.81

-.77 

-.82 

-.80 

-.79 

-.75 

-.07

-.03 

-.05 

-.01 

-.02

-.85 

07

-.84

-.86

-.82 

.62 

.61 

.63

-.25

-.22

-.25

CaO CaO 

M-XRF D-ICP

1

1 

.72 

.73 

.73 

.72 

.73 

-.84 

-.80 

-.88 

-.85 

-.84 

-.81

-.78 

-.82 

-.80 

-.79 

-.76

-.02 

-.05 

-.01 

-.02 

-.85

07

-.84

-.86

-.82 

.64 

.63

-.22

-.24

1 

.71 

.72 

.72 

.71 

.72 

-.84 

-.81 

-.88 

-.86 

-.85 

-.81

-.78 

-.82 

-.80 

-.79 

-.76

fift

-.04 

-.06 

-.02 

-.04 

-.86

QQ

-.84

-.86

-.83 

.62 

.61 

.62

-.26

-.23

-.26

M

X

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

— 

-
REVIEW: ELEMENTAL SOURCES—THE MODERN OCEAN

P <S >O <S O\ -* ft 10 in ts — ts — r r r

collection and analysis, but also to such natural factors as 

variations among species, geography, and growth rates 

(Eisler, 1983). Also, waste products (such as molts and fecal 

material of zooplankton), which constitute a major contribution of organic matter to the sea floor, commonly have 

minor-element contents significantly greater than those of 

plankton itself (table 7).

The distributions of Cd, Cu, Cr, Ni, Se, V, and Zn in 

the water column, relative to those of PO^", NO^, and 

Si(OH)4, indicate that organic detritus is the major carrier 

of many minor elements from seawater to the sea floor. 

NOJ and PO^" are the limiting nutrients for phytoplankton 

productivity in the ocean today (Sverdrup and others, 1942; 

Broecker and Peng, 1982; Codispoti, 1989), and Si(OH)4 

may be a limiting nutrient in some ocean-margin areas 

(Nelson and others, 1981). These nutrients are extracted 

from seawater in the photic zone during photosynthesis 

and returned to the ocean at depth by way of bacterial 

respiration. As much as 15 to 40 percent of the initial 

paniculate organic matter survives to the sea floor, a function largely of sea-floor depth and primary productivity 

(Sarnthein and others, 1988; Baines and others, 1994). Thus, 

concentrations of PO4~ and NOj in surface water are 

relatively low and even can closely approach zero; they 

increase sharply below the photic zone to the thermocline 

and then remain relatively constant below approximately 

500-m depth.

Cd, Cu, Cr, Ni, V, and Zn all show a similar depth 

profile. Cd parallels PO^" (Boyle and others, 1976), more 

so than other minor elements. Zn and Ni profiles resemble 

that of Si(OH)4 (Sclater and others, 1976; Bruland, 1983). 

For Zn, the Zn:Si(OH)4 ratio in seawater (Broecker and 

Peng, 1982) corresponds to a Zn content in opal of approximately 60 ppm; however, the measured content averages 

only 5 to 10 ppm (Martin and Knauer, 1973), much less 

than its bulk content in plankton of 110 ppm (table 5). Thus, 

the high measured content of Zn in organic detritus (Collier 

and Edmond, 1984) and its much lower measured content in the siliceous fraction of plankton (Martin and 

Knauer, 1973) indicate that it and, probably, Ni are associated dominantly with the soft parts of organisms, similar to 

Cd.

Se is unique among this group of elements; significant 

amounts exist in two valence states, with SeO^" somewhat 

more abundant than SeO^" (Measures and others, 1980). 

The distribution of SeO^" approaches zero in the photic 

zone, similar to that of Cd. Although SeO4~ also shows a 

nutrient-type profile, it does not approach zero in the photic 

zone, similar to Si(OH)4.

The depth profiles of nutrients and minor elements in 

seawater can be used to evaluate the interpretation that the 

average measured minor-element composition of plankton 

(table 8) approximates the composition of organic matter 

settling through the water column and onto the sea floor. For 

example, the concentration ratio of NOj and
10 REVIEW: ELEMENTAL SOURCES—THE MODERN OCEAN 

Table 4. Correlation coefficients for selected minor elements in the Monterey Formation.

[All values rounded to nearest hundredth. Laboratories: D, U.S. Geological Survey, Denver, Colo.; X, X-Ray Assay Laboratory, Don Mills, Ontario, 

Canada. Methods: ICP, inductively coupled plasma spectroscopy; NAA, instrumental neutron-activation analysis; XRF, X-ray-fluorescence spectroscopy]

Laboratory- Ba

Ba— —

Ba— —

Ba— — -

Co— —

Co— — -

Co— — -

Cr— — -

Cr— —

Cr— — -

Cr— — -

Mo— —

Mo— —

Mo— —

Sc— —

Sc— —

Sc— —

Zn— —

Zn— — -

Zn— —

method

X-NAA

X-ICP

D-ICP

X-NAA

X-ICP

D-ICP

X-NAA

X-ICP

X-XRF

D-ICP

X-NAA

X-ICP

D-ICP

X-NAA

X-ICP

D-ICP

X-NAA

X-ICP

D-NAA

X-NAA

1

-.37

-.39

.34

.29

.34

.80

.80

.77

.79

.86

.83

84

.23

.23

70

81

.81

.78

Ba

X-ICP

1

.08

.51

.42

.44

-.08

-.11

-.01

-.10

-.32

-.28

-.28

.51

.54

.55

-.23

-.13

-.14

Ba

D-ICP

1

-.30

-.18

-.19

-.49

-.52

-.47

-.48

-.40

-.44

-.43

-.14

-.16

-.10

-.53

-.58

-.55

Co

X-NAA

1

.95

.96

.67

.64

.68

.62

.31

.31

.31

.94

.93

.93

.42

.53

.48

Co

X-ICP

1

.96

.57

.55

.60

.52

.28

.28

.27

.96

.96

.95

.32

.44

.37

Co

D-ICP

1

.62

.58

.61

.56

.34

.32

.32

.97

.96

.96

.40

.48

.44

Cr

X-NAA

1

.99

.98

.99

.75

.75

.75

.52

.53

.50

.89

.94

.92

Cr

X-ICP

1

.97

1.00

.77

.78

.78

.48

.50

.46

.91

.96

.94

Cr

X-XRF

1

.97

.72

.73

.72

.54

.56

.52

.83

.91

.88

Cr

D-ICP

1

.75

.76

.76

.46

.47

.44

.91

.96

.94

Mo

X-NAA

1

.98

.99

.18

.21

.17

.82

.84

.82

Mo Mo Sc Sc Sc Zn Zn Zn

X-ICP D-ICP X-NAA X-ICP D-ICP X-NAA X-ICP D-ICP

1

1 00 1

.16 .15 1

.20 .19 .99 1

.15 .14 .99 .99 1

.83 .83 .27 .27 .23 1

.86 .86 .36 .39 .34 .97 1

.84 .84 .31 .33 .29 .98 .99 1

8-seawater[NOj] =

NOj(deep ocean) - NO^photic zone) 

PO|~(deep ocean) - PO^photic zone), (1)

based on chemical analyses of seawater, should equal the 

average atomic ratio in plankton of 15:1, if only metabolic 

and advective processes determine their distributions in the 

oceans. Although there is considerable scatter in the measurements of the composition of plankton, the average N:P 

ratio approaches the 8-seawater value. The ratios of minor 

elements in plankton also should equal their 8-seawater 

values. This relation seems to be true for Cd, but the 8- 

seawater values for Cu, Cr, Ni, Se, and V are higher, and for 

Zn lower, than the mean element:? ratios in plankton. Boyle 

and others (1977) explained the distribution of Cu in the 

deep ocean by a combination of biologic and nonbiologic 

processes, whereby the nonbiologic processes involve scavenging of Cu throughout the water column by settling particles and recycling of Cu into the bottom waters from oxic 

pelagic sediment. These and other nonbiologic processes 

also might explain the high 8-seawater values for Cr, Ni, Se, 

and V, although their marine chemistries have not been 

examined as thoroughly as that of Cu. Nonetheless, the 

similarities of the seawater-concentration-versus-depth profiles of many minor elements to those of NOj and PO^~- and 

the fact that their 8-seawater values are within a factor of 5 

of the average compositional ratios of plankton (table 8), 

suggest that the elemental composition of plankton approximates the average composition of marine organic detritus 

settling into the deep ocean and, presumably, onto the sea 

floor.

Nonbiologic processes might influence the distributions 

of many minor elements in the deep ocean. Their influence 

can be demonstrated for Cu if we consider the similarity of 

its 8-seawater value based only on the uppermost 2,000 m of 

seawater (1.6x10~3) to the Cu:P ratio in plankton (1.4xlO~3) 

and its 8-seawater value based on bottom water (3.5xlO~3). 

Thus, nonbiologic processes might contribute relatively little 

to the minor-element distributions in shallow-basin and continental-shelf environments along the margins of the oceans.

The distributions of REE's, Mo, and U are little influenced by the biologic cycle. Mo and U concentrations are 

constant with depth (Broecker and Peng, 1982; Emerson 

and Huested, 1991). Mo is mildly bioreactive (table 5), but 

its uptake by plankton in the photic zone and remineralization 

at depth by bacteria are simply insufficient to affect measurably its vertical distribution in the water column. REE concentrations increase continuously with depth in the ocean, 

an observation that has been explained in terms of nonbiologic processes (de Baar and others, 1985). Although REE 

contents are relatively high in handpicked biogenic siliceous 

tests (Elderfield and others, 1981), indicating that REE's 

might be incorporated into the biogenic-silica fraction, their 

low concentrations in bulk organic matter (table 5) suggest 

that the REE contents are very low in silica, possibly similar 

to those in biogenic calcite (Palmer, 1985).

Throughout the rest of this report, we present the content of each minor element in plankton as a single value that 

we consider to be best defined by average plankton, although 

it is unlikely to be a single value, nor is it well defined. We 

note that whereas the absolute content of a single minor 

element can vary by several orders of magnitude, the interelement ratios vary by no more than a factor of approximately 20; therefore, we focus our attention on these ratios.
REVIEW: ELEMENTAL SOURCES—THE MODERN OCEAN 11

Table 5. End-member major-element-oxide and minor-element contents in 

sedimentary fractions of the Monterey Formation in comparison with standards.

[Major-element-oxide contents in weight percent; minor-element contents in parts per million. 

Dashes, not available. NASC, North American Shale Composite (Gromet and others, 1984); 

WSA, World Shale Average (Wedepohl, 1969-78). Values for detrital fraction of the Monterey 

Formation (in parentheses) represent minimums or single trends, calculated from plots of 

element or element oxide versus detritus; neither a minimum nor a single trend was recognized 

in several plots, in which case no value is listed. Contents of other minor elements in WSA and 

in detrital fraction (in parentheses) are as follows: Ag, — (0.5); As, 10 (10); Ba, 640 (670); Cs, 

5.2 (5.4); Ga, 21 (22); Hf, 3.8 (4.0); Li, 60 (50); Sc, 13 (16); Sr, 125 (220); Th, 12 (10.5); Y, 26 

(32). Data sources: Biogenic SiO2 , Elderfield and others (1981); calcite, Palmer (1985); 

organic matter, Sverdrup and others (1942), Elderfield and others (1981), and Brumsack 

(1986)]

Detrital fraction Marine biogenic fractions Authigenic 

fraction

WSA or NASC

(Monterey Biogenic SiO2 Calcite 

Formation)

Organic matter Apatite

Major-element oxides

P205— - 

TiOj — - 

K2O —— 

CaO ——

SiOj

0.16

.77 (0.81) 

3.2 (3.2)

3.09 - 56.0 

6.75 (6.33) 

17.1 (17.4)

58.4 100.0

1.74

.050

40.7

55.5

Minor elements

!_„__

Pr

NdSm —— - —— — _

Eu _______

Gd -—-————__

Dv— Ljy

Ho~ - - ——

Pr

31.2(31)

66.7 (61)

27.4 (24)

5.59 (5.3)

1.18(1.12)

-

RS

5.80

8.21

6.71

1.56

.40

1.78

1 AQ

.128

.105

.106

.019

.004

.022

.024

.14

.23

30

_

-

-

.01

-

_

-

-

Yb- ———————

Q. ____________

Mo -_————

Ni

Se- —_____—

U- - - —

y ___________

3.06 (3.0) 

.456 (0.45) 

35.0 

.2 

19.0 

83.0 

2.6 

44.0 

1.0 

3.0 

110 

100

0.86 .015

.700 11.0 

12.0 

1.0 

2.0 

2.0 

7.5 

3.0

3.0 

110.0

-

-

HYDROGENOUS SOURCE

Two mechanisms have been invoked by geochemists to 

account for the accumulation directly from seawater of minor elements in marine sediment. One mechanism involves 

equilibrium thermodynamics, first treated in depth by 

Krauskopf (1956) and Garrels and Christ (1965). The second mechanism, proposed by Goldberg (1954) to explain

the incorporation of seawater-undersaturated minor elements 

into the inorganic phases of pelagic sediment, promotes 

seawater scavenging throughout the water column by both 

organic and inorganic paniculate matter.

The major seawater redox reactions that drive the precipitation-dissolution reactions of individual minor compounds can be written in a simplified form as follows 

(Froelich and others, 1979):
12 GEOCHEMISTRY OF MINOR ELEMENTS IN THE MONTEREY FORMATION, CALIFORNIA

Table 6. Major components in sedimentary rocks of the Monterey Formation at Naples Beach and 

Lions Head, Calif.

[All values in weight percent, calculated from major-element-oxide contents]

Sample (fig. 1)

KG-1

KG-2

KG-3

KG-4

KG-5

KG-6

KG-7

KG-8

KG-9

KG-10

KG-11

KG-12

KG-1 3

KG-14

KG-1 5

KG-1 6

KG-1 7

KG-1 8

KG-19

KG-20

KG-22

KG-24

Silica

3.35

6.49

4.85

5.11

34.85

9.70

36.07

12.50

3.15

20.46

45.82

28.3

32.51

18.05

32.67

17.17

30.18

11.52

2.32

15.45

24.45

26.91

Detritus

31.92

35.06

64.40

55.66

36.40

64.96

49.34

61.60

70.00

30.46

18.37

57.12

51.18

59.92

39.09

24.70

19.71

19.66

2.07

67.76

24.25

43.34

Apatite

5.16

8.25

6.30

1.54

1.35

.82

.09

1.53

3.09

.60

.27

.20

0

.16

.68

2.17

8.60

.23

.63

.50

4.34

3.52

Dolomite

1.43

2.88

7.01

1.40

1.80

1.66

.46

2.24

9.79

5.81

3.24

2.37

1.85

5.72

6.17

41.30

.65

53.03

91.14

5.47

6.36

0

Calcite

37.76

14.54

.02

2.60

11.06

3.84

.31

1.27

2.60

32.44

24.47

0

0

7.58

13.02

4.98

28.83

11.02

3.77

0

29.30

.55

Organic matter

15.03

23.85

9.77

24.60

5.00

8.25

5.96

8.69

6.18

6.23

3.85

1.34

1.34

3.53

5.88

8.40

10.28

1.35

1.40

6.44

9.84

22.20

Table 7. Weight ratios of minor elements (in parts per million) to Fe (in weight percent) in fecal 

matter, shale, and plankton.

[Data on fecal matter from Fowler (1977); data on shale are for World Shale Average (WSA) from Wedepohl 

(1969-79) or, for rare-earth elements, for North American Shale Composite (NASC) from Gromet and others 

(1984). Fe contents (in weight percent): fecal matter, 2.4; WSA, 4.72; NASC, 4.43; plankton, 0.034]

Fecal material — 

Shale— --------

Cu

94

a o

315

Zn Cd

400 4.0 

on c\fi

Sc

1.2

tfj

Cr

16 

16

CO

Mn

100

112

Co

1.5

•5 r

29

Ni

8.3

o o

210

Ce

83 

17

Eu

.28 

.30

Table 8. Minor-element contents in organic matter (plankton) and seawater.

Organic matter Element:? ratio 

(ppm) (organic matter)

Seawater

8-seawater concentration 

(weight ratio) at ~2,000-m depth 

(Ppb)

Cd

Co --————

Q. ________

Cu- —————

Mo —————

Ni -—__—_-

Se

U- - - -

V -

TJI £Al

REE's (La)—

12

<1

2.0

11

2

7.5

3.0

- 1

3.0

110

<1

1.6x10 3

-

.26x10-3

1.40x10-3

.26x10-3

1.0x10-3

.40x10-3

.39x10-3

14.00x10-3

-

1.3x10 3

-

1.6x10-3

1.6x10-3

-

5.3x10-3

1.5x10 3

1.1x10-3

6.1x10-3

-

.078

.0012

.21

.23

10.60

.47

.13

3.00

1.80

.39

.0052
REVIEW: ELEMENTAL SOURCES—THE MODERN OCEAN 13

Oxygen respiration:

10CH2O + 10O2 + 10CaCO3 =

20HCOJ+ 10Ca2+

Denitrification:

10CH2O + 8NOJ + 2CaCO3 =

4N2 + 12HCOJ + 4H2O + 2Ca2+

Sulfate reduction:

10CH2O + 5SO2,- + 5CaCO3 =

15HCOj + 5Ca2+

(2)

(3)

(4)

Organic matter, expressed here as CH2O but better 

represented by the formula (CH2O)]06(NH3 ), 5 (H3PO4) (minor elements)0 0^, is the most important electron donor in 

the oceans, and O2, NO3 , and SO2" are the most important 

electron acceptors. The hierarchy of these reactions is determined by the one yielding the greatest free energy (Froelich 

and others, 1979). Thus, reaction 2 proceeds until O2 decreases to a concentration such that denitrification yields 

equal free energy, and so on.

Within several ocean-margin basins, advection is weak 

enough, and the flux of settling organic matter great enough, 

to allow depletion of successively more favored electron 

acceptors with depth in the water column. These basins 

include the Gulfo Dulce (Costa Rica), Baltic Sea, Black Sea, 

Cariaco Trench (Venezuela Shelf), and several fiords at 

high latitudes (Richards, 1965; Emerson and others, 1979; 

Jacobs and others, 1985, 1987; Emerson and Huested, 1991). 

Profiles of O2, NOJ, and H2S show that O2 is abundant in 

the surface mixed layer, owing to mixing with atmospheric 

O2 and to photosynthesis, but decreases in the water column 

below the mixed layer, in response to oxygen respiration; 

O2 is present at a very low concentration at intermediate 

depths (Emerson and others, 1979) under conditions of denitrification, the depth interval over which NO3 shows a sharp 

decrease in concentration; and both O2 and NO3 are virtually absent in the bottom water, under conditions of sulfate 

reduction (eq. 4), in the presence of H2S. Sulfate reduction 

continues into the sediment until SO2~ is depleted in the 

pore water, at which depth the residual labile organic matter 

begins to be broken down through methanogenesis and fermentation reactions (equations not shown). In the Santa 

Barbara Basin (California Continental Borderland) and Darwin Bay (Galapagos Islands), bacterial respiration in the 

bottom water does not proceed beyond denitrification.

In contrast, the open ocean exhibits oxygen respiration 

virtually throughout the water column. Denitrification occurs in the oxygen-minimum zone (OMZ, fig. 3), but only 

along the Peru and Mexico Shelves in the eastern Pacific 

Ocean (Codispoti, 1980) and at a few other localities of 

limited areal extent in the Atlantic and Indian Oceans. Although the OMZ is present at intermediate depth throughout 

most of the oceans, only in these relatively small areas is the 

balance between advection in the OMZ and primary productivity in the photic zone such that bacterial oxidation of 

settling organic matter drives down the O2 content of the 

water column within the OMZ to a value that promotes 

denitrification.

Several minor elements also serve as electron acceptors, including CrO^", Fe(OH)3 MnO2, MoO^, SeO^, 

UO2(CO3)2~, H2VO4~, and other components of seawater 

that might be reduced by way of oxidation of organic matter 

(table 9). By including the half-cell reaction for the oxidation of organic matter, as we did in equations 2 through 4, 

Fe(III) reduction can be written in the following form:

10CH20 + 40Fe(OH)3 + 60HCO3 -+ 70Ca2+ =

70CaC03 + 40Fe2+ + 1 OOH2O. (5)

Its reduction occurs before that of sulfate (table 9) and 

toward the end of denitrification (Berner, 1980; Bender and 

others, 1989); SeO2~ and CrO2~ also are reduced under 

conditions of denitrification (table 9; Measures and others, 

1983; Murray and others, 1983).

These minor elements contribute insignificantly to the 

actual oxidation of organic matter, owing to their low concentrations in seawater, but their accumulation on the sea 

floor, as a result of their reduction and (or) precipitation, 

contributes in a major way to our identification of past redox 

conditions in the water column. Under conditions of oxygen 

respiration, inorganic precipitates consist mostly of Fe and 

Mn oxyhydroxides (Landing and Bruland, 1987). Other minor elements are undersaturated in oxic seawater, but high 

concentrations of several minor elements in deep-ocean 

ferromanganese nodules indicate that a fraction coprecipitates 

with Fe and Mn oxide phases or is scavenged by these 

oxides. Pelagic sediment, however, is a minor sink for many 

minor elements, except Mn (Lyle and others, 1984). Its high 

metallic-element contents reflect very low bulk-sedimentaccumulation rates rather than high minor-element-accumulation rates.

Within basins that exhibit sulfate reduction in bottom 

waters, Fe2+, Cu+, Cd2+, and Zn2+ exhibit reduced concentrations in the bottom water (Brewer and Spencer, 1974; 

Jacobs and others, 1985, 1987), possibly owing to precipitation as sulfides; CrO2~ is reduced and precipitates as Cr(OH)3 

(Emerson and others, 1979); and H^VO^ should be reduced 

to V2O4, or, possibly, V(OH)3 (Wanty and Goldhaber, 1992). 

Mo, Se, and U also show lower concentrations in the bottom 

water than in the oxic surface water (Bruland, 1983; Anderson and others, 1989a; Emerson and Huested, 1991); they 

too might precipitate, possibly by some form of the reactions listed in table 9.

Minor elements in the modern environment, however, 

seldom behave ideally, or simply. For example, the thermodynamic properties of U require that it is present in seawater 

as UO2(CO3)^- (Langmuir, 1978) and UO2(CO3 )^; the one 

should be reduced under conditions of denitrification and 

the other under conditions of sulfate reduction (table 9). The
14 GEOCHEMISTRY OF MINOR ELEMENTS IN THE MONTEREY FORMATION, CALIFORNIA

distribution of U in the Black Sea (Anderson and others, 

1989) supports its reduction under conditions of sulfate 

reduction. It exhibits no variation through the intermediate 

zone of denitrification but shows a strong decrease in the 

bottom water. Isotopic evidence further suggests that reduction and precipitation of U actually occur in the sediment 

pore-water environment (Anderson and others, 1989a). This 

distribution indicates that the complex UO2(CO3)3~ is the 

stable seawater species. Similarly, V should be reduced 

under strongly denitrifying conditions (table 9), but its disSea level

respiration

NO3- reduction

cc&

H 

H 

H

S 

h— zI

X

H

&H 

H

o

U

o

02

respiration

— o

—s

U 

Zh—l

a

H

Sea level

O2 respiration Photic zone

±

V SO42- reduction

Methanogenesis

B

_« cc

Figure 3. Schematic diagram illustrating seawater and sediment chemistry in a marine-shelf 

environment with high primary productivity and weak advection at intermediate depth (top), and in 

a shallow-silled basin with low to moderate primary productivity and extremely weak advection 

(bottom). Modern examples of shelf environment are the Peru and Namibia Continental Shelves, 

and of basin environment the Black Sea and the Cariaco Trench. Fundamental difference between 

these two environments is depth of most intense reduction in water column: at intermediate depth 

on shelf and at maximum depth in basin. Shaded area, oxygen-minimum zone (OMZ).
REVIEW: ELEMENTAL SOURCES—THE MODERN OCEAN

Table 9. Half-cell reactions, assuming standard-state conditions.

[Boldface, major reactions in oxidation of organic matter. Activity coefficients calculated by using the Debye-Hiickel equation (Wagman and 

others, 1982); a, effective ionic diameter used in the Debye-Hiickel equation (from Nordstrom and Munoz, 1985, or estimated from their table 

7-4). Seawater concentrations of dissolved species (in moles per kilogram) are those at approximately 2,000-m depth. The pH was taken to 

be 7, although it is closer to 8 under conditions of oxygen respiration and 7.5 under denitrification. Data sources for thermodynamic constants 

and species concentrations in seawater: 1, Bruland (1983); 2, Latimer (1953); 3, Wagman and others (1982); 4, Landing and Bruland (1987); 

5, Broecker and Peng (1982); 6, Murray and others (1983); 7, Elderfield (1970); 8, de Baar and others (1985); 9, Langmuir (1978); 10, Jacobs 

and others (1985); 11, Collier (1984); 12, Boyle and others (1976); 13, Collier (1985); 14, Emerson and Huested (1991); 15, Anbar and others 

(1992); 16, Koide and others (1986)]

15

Eh

1.099

.805

.704

.702 

.698

.545

.320

.296

.153

.013 

-.018

-.040

-.055

-.055

-.137

-.162

-.170

-.175 

-.188

-.209

-.210 

-.250

-.250

Half-cell reaction

3Co2+(aq) + 4H2O(i) -» Co3O4(S) + 2e- + 8H+(aq)

2H2O(i) -» O2(g) + 4e~ + 4H+(aq)

Mn2+(aq) + 2H2O(i) -» MnO2(S) + 2e~ + 4H+(aq)

r(aq) + 3H20(i) -» I03~( aq) + 6e- +6H+(aq) 

N2(g) + 6H20(]) -» 2N03-(aq) + 10e- + 12H+(aq)

Cr(OH)3(s) + H2O(i) -» CrO42-(aq) +3e~ + 5H+(aq)

Ce3+(aq) + 2H2O(i) -» CeO2(s) + e~ + 4H+(aq)

Fe2+(aq) + 3H20(i) -» Fe(OH)3(s) + e~ +3H+(aq)

Cu+ -> Cu2+ + e~

U02(s) + 2HC03-(aq) -» U02(C03 )22-(aq) + 2e-+ 2H+(aq) 

2Fe2+(aq) + 3H2O(i) -» Fe2O3(s) + 2e~ + 6H+(aq)

V204(s) + 4H20(i) -> 2H2V04~(aq) + 2e- + 4H+(aq)

HS~(aq) + 4H2O(i) -» SO42~(aq) + 8e~ + 9H+(aq)

Cu 2S(s) + 4H2O(i) -» SO42-(aq) + 2Cu+(aq) + 8e~ + 8H+(aq)

CdS(S) + 4H20(i) -» S042-(aq) + Cd2+(aq) + 8e~ + 8H+(aq)

ZnS(S) + 4H2O(i) -» SO42-(aq) + Zn2+(aq) + 8e~ + 8H+(aq)

MoO2( S) + 2H2O(i) -^ MoO42-(aq) + 2e~ + 4H+(aq)

MoS2(s) + 12H2O(i) ^ MoO42-(aq) + 18e~ + 2SO42-(aq) + 

24H+(aq) 

NiS(S) + 4H2O(i) -^ S042-(aq) + Ni2+(aq) + 8e~ + 8H+(aq)

FeS(s) + 4H2O(i) -^ SO42-(aq) + Fe2+(aq) + 8e~ + 8H+(aq)

U02(s) + 3C03-(aq) -* U02(C03 )34-(aq) + 2eReO2(s) + 2H2O(i) -^ ReO4~(aq) + 3e~ + 4H+(aq)

HS~(aq) + 4H2O(i) -» SO42-(aq) + 8e~ + 9H+(aq)

Seawater concentration, in moles T> Q<V Q n 

a , ., . , Reference 

per kilogram or partial pressure

6

--

6

3 

4 

3

4

9

6

-

4.0 

4.5 

6

5.6

35 

4

4

2.5

4 

6

4 

6

4.5

4.5 

5 

4 

6

4 

6

4.5 

5.5 

4.5

35 

4

Co2+ = 2.04X10- 1 1

O2 = 0.2 atm

Mn2+ =2.5xlO-10

r = s.oxio-9,

IO3~= 4.5xlO-7 

NO3~= 3.9xlO-5, 

N2(g) = 0.8 atm 

CrO42~= 4.04x1 0-9

Ce3+ =1.0xlO- 11

Fe2+ = 1.20X10-9

iCu = 3.59x10-9, 

Cu+= 1.80x10-9

HCO3~= 2.47x1 0-3 , 

UO2(CO3)22~= 1.26x1 0-8 

See above

H2VO4~ = 4.0x1 0-8

HS~=7.75xlO-25, 

SO42- = 2.8xlO-2 

SO42-=2.8xlO~2, 

Cu+ = 3.59x1 0-9

SO42~=2.8xlO-2, 

Cd2+ = 6.94xlO-10

SO42-=2.8xlO-2, 

Zn2+ = 5.97x1 0-9

MoO42~= l.lxl 0-7

SO42~=2.8xlO-2, 

MoO42~= l.lxlO-7 

SO42~=2.8xlO-2, 

Ni2+ = 8.01x10-9

SO42-=2.8xlO~2, 

Fe2+ = 1.20x10-9

CO3" =1x10-4, 

UO2(CO3)34~= 1.26x1 0-8

ReO4~=4.5xlO-n

HS~= 2.8x10-2, 

SO42- = 4.3xlO~6

1,2

3

3,4

1,3

3,5 

2,6,7

3,8

3,4

1,3

3,5,9

2,11

3,5 

1,3,10

1,3,5,12

1,3,5

3, 13

3, 13, 14 

1,3,5,10

1,3,4

3,5,9 

3, 15, 16

3,5
16 GEOCHEMISTRY OF MINOR ELEMENTS IN THE MONTEREY FORMATION, CALIFORNIA

tribution in several basins (Emerson and Huested, 1991) 

suggests it is reduced only under sulfate-reducing conditions.

The concentration of Ni in seawater and the Eh conditions established in sulfate-reducing environments predict 

that Ni too should precipitate as a sulfide (table 9). At first 

glance, its depth profile in the water column, which shows 

no depletion in the bottom water relative to the surface 

water (Jacobs and others, 1985, 1987), suggests that it does 

not. However, the profile simply requires that Ni removal 

from bottom water is limited to the amount added to bottom 

water by way of bacterial oxidation of organic matter. Still, 

Ni should exhibit a depth profile similar to those of Cu and 

Cd. Several reasons likely account for its apparent nonideal 

behavior and the nonideal behavior of other minor elements. 

First, our calculations of stable species (table 9) are limited 

to those for which we have equilibrium constants, and these 

may not necessarily be the species that actually control the 

solubility of, for example, Ni and U. Second, the thermodynamic constants used in our calculations are from one of 

several recently published lists of values, which do not 

always agree. Third, we have not fully evaluated the effects 

of complexation (Kremling, 1983; Jacobs and others, 1985; 

Landing and Lewis, 1991), which would increase solubilities. Fourth, we have not considered diffusion across the 

benthic boundary layer (see below).

Under the intermediate redox condition of denitrification, metallic sulfides will not precipitate. Cr(OH)3 , however, 

is stable (Murray and others, 1983), and the thermodynamic 

properties of V (table 9) allow for its reduction from J^VO^ 

to the more reactive ionic state VO2+ (Sadiq, 1988) and to 

V2O4 near the NOg-SOjf-reduction boundary (table 9). The 

higher concentration of V in sea-water than of Cr (table 8) 

and the possible removal of V from the water column during 

denitrification make V a more conspicuous index of sediment from this environment than is Cr.

REE's respond still differently in seawater. They are 

adsorbed onto seawater paniculate phases under oxic and 

denitrifying conditions and returned to seawater under sulfate-reducing conditions. Within the open ocean, aceticacid-soluble particulate phases show an increase in REE 

content and increasingly positive Ce anomaly with depth 

(Sholkovitz and others, 1994); however, sediment-accumulation rates suggest the flux is quite low. Within the denitrification zone of the Cariaco Trench and the Black Sea, 

above the zone of sulfate reduction (Hashimoto and others, 

1983; Codispoti and others, 1991), the 3+-valence-state 

(within the marine environment, all REE's except Ce) light 

REE's La, Pr, Nd, and Sm show strong concentration minimums, requiring their removal onto particulate phases (de 

Baar and others, 1988, German and others, 1991; Schijf and 

others, 1991). Toward the NOj-SO^-reduction interface 

and into the sulfate-reducing water in both basins, their 

concentrations increase sharply. Within the denitrification 

zone of the OMZ in the eastern Pacific Ocean, the 3+-

valence-state REE's also show concentration minimums. 

They are scavenged by particulate phases, most likely 

oxyhydroxides of Mn (German and others, 1993) and Fe 

(Sholkovitz, 1993), more so under denitrifying than oxic 

conditions, and released to solution under sulfate-reducing 

conditions. The carrier phase in the denitrification zone in 

the OMZ of the eastern Pacific is unlikely to be an Mn 

phase. Dissolved Mn shows a concentration maximum, 

whereas REE's exhibit concentration minimums (Klinkhammer and Bender, 1980; de Baar and others, 1985; German 

and others, 1991). Particulate Mn is reduced, possibly by 

some form of the reaction

2Mn3O4 + CH2O 10HCO

6Mn2+ + 1 !CaCO

!Ca2+ = 

6H2O. (6)

Thus, although the mechanism whereby the 3+-valencestate REE's are transferred to the sea floor within the hydrogenous fraction remains problematic, the redox conditions 

under which it is enhanced or diminished are well established.

Ce is somewhat more complex than the other REE's. Its 

occurrence as insoluble Ce(OH)4 under oxic conditions (table 

9) accounts for the negative Ce anomaly (see fig. 4 for 

definition) of seawater. Reduction back to a 3+ valence state 

under denitrifying conditions accounts for the increase in Ce 

concentration and for the more positive Ce anomaly of the 

OMZ in the eastern Pacific Ocean and the Cariaco Trench 

(de Baar and others, 1988). In the Black Sea, this trend is 

reversed (German and others, 1991; Schijf and others, 1991): 

In the denitrification zone, the Ce concentration decreases to 

a minimum, as does the Ce anomaly, paralleling the trends 

of the 3+-valence-state REE's.

Scavenging by the seawater particulate phases of other 

minor-element ions (Balistrieri and others, 1981; Li, 1981; 

Whitfield and Turner, 1987; Clegg and Sarmiento, 1989) 

probably is equally complicated by such geochemically complex water columns as that in the Black Sea and Cariaco 

Trench, but the results of research into metallic-ion adsorption under oxic conditions clearly identify the importance of 

scavenging for many minor elements. Evaluating the importance of minor-element scavenging in the Monterey Formation, or in any ancient rocks, however, is hampered by the 

difficulty of identifying a marine fraction for those minor 

elements that have been well studied, are nonbioreactive, 

and are strongly scavenged. Th is the most intensively examined element in this group, but its high content in the 

detrital fraction of sediment and sedimentary rocks, relative 

to its concentration in seawater—that is, relative to a possible seawater contribution—makes it unlikely that we might 

identify a marine fraction for Th in the Monterey Formation 

from bulk analyses. Of the other minor elements for which 

we have analyzed, Zn and Cu also are likely to be scavenged, and Ni and Cd should not be, or much less so (Clegg
REVIEW: ELEMENTAL SOURCES—THE MODERN OCEAN 17

and Sarmiento, 1989; Balistrieri and Murray, 1984). Thus, 

within the group of minor elements for which we have 

analyzed, hydrolytic scavenging should enrich Zn over Ni 

and Cd, owing to the greater tendency for Zn to be adsorbed 

onto particulate matter (under seawater oxic conditions) and 

its higher concentration in seawater (for example, 5 times 

that of Cd). The distributions of Zn, Ni, and Cd in the marine 

fraction of sediment of the Gulf of California (Brumsack, 

1986), however, reflect a strong, possibly solely, biogenic 

input, suggesting that scavenging is a minor process under 

conditions of high primary productivity.

Interpretation of the accumulation of metallic elements 

in ancient rocks on the basis of their accumulation in modern sediment is further complicated by diffusion across the 

benthic boundary layer. Where 0-,-depleted pore waters of 

organic-matter-enriched sediment are present close to the 

sea floor, Mo, U, V, and Cr can diffuse from seawater across 

the seawater-sediment interface and be retained in the sediment (Calvert, 1976; Manheim and Landergren, 1978; 

Brumsack, 1983, 1986; Francois, 1988; Pedersen and others, 1989; Emerson and Huested, 1991; Klinkhammer and 

Palmer, 1991), possibly independently of redox conditions 

of the bottom water. Near-surface sediment in the Gulf of 

California exhibits increasing concentrations of Mo, Cr, and 

V with depth. In absolute terms, however, this enrichment 

mechanism results in only slightly elevated minor-element 

contents (Brumsack, 1986); sediment on the Peru Shelf, 

which also accumulates under denitrifying conditions, shows 

no evidence of minor-element diffusion across the benthic 

boundary layer—minor-element concentrations are relatively 

constant in the uppermost 35 to 40 cm of sediment (Dean 

and Arthur, 1992).

The relative accumulation rates of metallic elements 

under these different redox conditions, in an area of high 

primary productivity, are summarized in figure 4. This diagram should be considered only in general terms because 

the elemental contribution of any single source changes 

with primary productivity, water depth, bulk-sediment-accumulation rate, and residence time of the bottom water, to 

name but four factors. Also, we exclude scavenging and 

diffusion as major mechanisms of minor-element enrichment under conditions of O2 depletion in the bottom water, 

except for REE's, although scavenging could be important 

for some metallic elements, however difficult it is to evaluate. Figure 4 is intended to show that the hydrogenous flux 

of minor elements to the sea floor will be low under oxic 

conditions, except for Mn and Fe, with REE's exhibiting a 

widely varying, but commonly positive, Ce anomaly; it will 

be virtually zero for Mn and high for REE's (negative Ce 

anomaly), Cr, and V under denitrifying conditions; and it 

will be zero for Mn and REE's and high for Cr, V, Mo, Se, 

Fe, Cu, Cd, and Zn under sulfate-reducing conditions. Although Fe precipitates as a sulfide under sulfate-reducing 

conditions, detection of a hydrogenous fraction is hampered 

by detrital and organic inputs, even under conditions of the

lowest bulk-sediment-accumulation rates, as noted above 

for pelagic deposits.

The failure of seawater profiles of several minor elements in modern basins to reflect the geochemistry of the 

bottom water—that is, the apparent absence of approach 

toward equilibrium between dissolved and solid phases

Particulate element fluxes to the sea floor

Marine fractions

Hydrogenous Biogenic 

Oxic Denitri- Sulfate 

respiration fication reduction Carbonate Opal

Organic 

matter

Fe 

Mn 

Cd 

Co 

Cr 

Cu 

Mo 

Ni 

Se

U

V 

Zn 

REE

„ * Pos. to Zero „ .. XT ,., 

Ce neg. to neg. Zero N<* Ne8- Neg.

O

o

Nonmarine 

fraction

Zero

Very high ^B High V Moderate 9 Low • Absent to very low

Figure 4. Generalized summary of elemental accumulation in 

marine sediment under conditions of high primary productivity in 

photic zone, where seawater (hydrogenous and biogenic) sources 

are not totally masked by detrital (terrigenous) source. Chart should 

be read across rather than down; for example, dominant sediment 

source of Cd under conditions of high primary productivity is 

organic matter. Under conditions of sulfate reduction in bottom 

water, as well as high primary productivity in photic zone, Cd also 

accumulates as an inorganic precipitate, CdS; its accumulation as 

an inorganic precipitate under bottom-water redox conditions of 

oxic respiration, or denitrification, is minor, as is its accumulation 

within detrital fraction of sediment under all conditions. Sizes of 

circles in any one row are unrelated, in absolute terms, to those in 

any other row; open circles are used in those cases for which 

theoretical considerations seem to conflict with observations. Ce*, 

Ce anomaly, defined as log [3Ce/(2La+Nd)], in which all three 

REE's have been normalized on an element-by-element basis to 

North American Shale Composite (see table 1). Dashes, no 

information available on which to estimate accumulation rate.
18 GEOCHEMISTRY OF MINOR ELEMENTS IN THE MONTEREY FORMATION, CALIFORNIA

(Cutter, 1982; Anderson and others, 1989a, b; Emerson and 

Huested, 1991)—urges further caution in the application of 

figure 4 to natural systems. One possible explanation for 

this apparent nonideality is suggested by the strong correlations in many samples of modern and ancient sediment 

between organic matter, albeit the residual fraction, and 

several minor elements, which should otherwise behave 

quite differently. We have stressed the transport of minor 

elements to the sea floor by organic matter, whose interelement ratios approach those of plankton. A second major 

role of organic matter is to supply minor elements to bottom 

waters by way of oxidized organic matter (Piper and Isaacs, 

1995), again in the ratios of plankton. A third role of settling 

organic matter may be to provide a surface on which the 

actual reduction and (or) precipitation of minor elements 

occurs. The presence of the oxidized species U(VI) in the 

sulfate-reduction zone of water column in the Black Sea 

(Anderson and others, 1989a) might be explainable by this 

mechanism. If, as we suggest, reduction and precipitation of 

seawater-dissolved elements partly depend on reactions at 

the surfaces of organic debris, then the rate of minor-element accumulation in the sediment would depend on the 

settling rate of organic matter—again, primary productivity. 

The degree to which minor-element removal from the water 

column then reflects equilibrium depends on a balance between primary productivity in the photic zone and residence 

time of the bottom water, as well as on the physical chemical 

properties of the dissolved species. In possible support of 

this interpretation, Mo, U, and V are strongly depleted in the 

bottom water of the Black Sea (long residence time) but 

very weakly depleted in the bottom water of Saanich Inlet 

(short residence time). Still, the distributions of Mo and V in 

the bottom water of Framvaren Fiord demonstrate the full 

complexity of our problem: Mo is depleted, whereas V is 

not (Emerson and Huested, 1991). Thus, the enrichments of 

minor elements, as illustrated in figure 4, represent idealized 

cases of marine shelf-slope and basin environments for which 

the detrital contribution of minor elements does not totally 

mask that of the marine environment, and equilibrium between particulate and dissolved species in seawater is approached, if not actually attained.

DIAGENETIC OVERPRINT

The depth profile of Eh in sediment of the ocean margins resembles that in the water column of anoxic basins, 

such as the Black Sea (see eqs. 2-5). The pore water of the 

surface veneer of sediment has the same redox properties as 

that of the immediately overlying bottom water, and the 

pore water becomes more reducing with depth. Burial exposes each parcel of sediment to ever more reducing conditions than that under which it accumulated. Thus, deciphering 

the marine fraction of metallic elements in sedimentary 

rocks is further complicated by the changing redox conditions to which the rocks were exposed immediately after 

deposition. The loss of a minor element from a sediment 

during early diagenesis can mask its source if its loss is 

substantial and differs from the relative loss of other elements. Sholkovitz (1973) reported a difference between the 

C:P ratio of sedimentary organic debris in the Santa Barbara 

Basin and that of plankton of 106:1 (Redfield and others, 

1963). Interelement ratios of minor elements may be similarly decoupled from those in settling organic matter, through 

diagenesis (Shaw and others, 1990).

Within fully oxygenated sediment, Cu, as well as Cd, 

Cr, V, Zn, Ni, and organic P, are, indeed, recycled into the 

overlying water column during early diagenesis. Sedimenttrap studies (Fischer and others, 1986) and pore-water studies of pelagic sediment (Callender and Bowser, 1980; 

Klinkhammer and others, 1982) reveal that as much as 90 

percent of the Cu is recycled at the sediment surface. The 

absence of Cr and U in excess of a terrigenous contribution 

in oxic sediment (Piper, 1988) requires that virtually all of 

the seawater-derived fractions of these elements also are 

recycled. Even with this loss, the albeit-slight retention of 

several minor elements by the sediment in oxic environments, largely associated with Fe and Mn oxides in both 

concretions (Mero, 1965) and finely dispersed phases (Piper, 

1988), is notable, owing to the very low rate of sediment 

accumulation in the pelagic environment rather than to a 

high flux of minor elements or a high retention efficiency on 

the sea floor of the deep ocean. Thus, different interelement 

ratios in the marine fraction of this sediment from those in 

marine organic matter and in the marine fraction of modern

120

50 100 150 200 250 

Cu CONTENT, IN PARTS PER MILLION

Figure 5. Zn:Cu interelement ratio in modem marine organic 

matter (shaded area on left), based on this ratio in plankton, in 

sediment from the Peru Shelf (circles), the Namibia Shelf, and the 

Santa Barbara Basin of the California Continental Borderland, and 

in fully oxic sediment (shaded area at bottom right) from a pelagic 

environment (diamonds). Labeled curves represent averages. See 

text for data sources.
RESULTS: ELEMENTAL HOST PHASES—THE MONTEREY FORMATION 19

sediment in ocean-margin areas (fig. 5), as discussed below, 

might allow for the identification of sedimentary rocks that 

accumulated under oxic conditions, on the basis of their 

current minor-element contents.

Profiles of the major oxidants (O2, NO^, and SO^~) in 

sediment on ocean margins are greatly steepened (Froelich 

and others, 1979; Berner, 1980; Claypool and Threlkeld, 

1983; Bender and others, 1989; Shaw and others, 1990) over 

those in pelagic and hemipelagic sediment, somewhat independently of the organic-matter content. At one extreme is 

sediment on the Peru and Namibia Continental Shelves 

(Baturin and others, 1972; Calvert and Price, 1983; Burnett 

and Froelich, 1988), which contains as much as 20 weight 

percent organic carbon (30-40 weight percent organic matter). The surface sediment is exposed to oxic seawater conditions, or to denitrification over that area of the sea floor 

impinged by the core of the OMZ (fig. 3), and sulfatereducing conditions extend upward to the surface of the sea 

floor in some areas (Froelich and others, 1988), owing to the 

high content of labile organic matter in the sediment and the 

low O2 content in the overlying bottom water. Sediment of 

the Santa Barbara Basin shows a similar redox profile. The 

sulfate-reduction zone extends to within 2 cm of the surface 

(Sholkovitz, 1973), yet the sediment contains as little as 3 

weight percent organic carbon.

Cu, Cd, Cr, Zn, and V are likely to be retained in this 

type of sediment, a conclusion supported by their behavior 

in sulfate-reducing seawater and in sediment pore water. 

Douglas and others (1986) and Shaw and others (1990) 

showed that Cu tends to be retained in the solid phases of 

such sediment. Cd and Zn are expected to behave similarly 

because of the low solubility of CdS and ZnS. The distributions of Cr and V in surface and near-surface sediment of the 

Gulf of California (Brumsack and Gieskes, 1983) reflect not 

merely their retention by, but their slight addition to, the 

sediment of O2-depleted environments, possibly owing to 

the reduction of Cr and V under denitrifying and more 

negative redox conditions (table 9). Their reduction, CrO^" 

to Cr(OH)3 and H2VO^ to VO2+ or V2O4, results in their 

greater stability under reducing than oxidizing conditions 

(Sadiq, 1988), although the formation of metal-organic complexes (Douglas and others, 1986; Heggie and others, 1986; 

Breit and Wanty, 1991) and various other possible reactions 

greatly complicate their geochemical behavior.

Minor-element contents and interelement ratios in sediment on the Peru and Namibia Shelves and the California 

Continental Borderland (fig. 5) support our interpretation 

that minor elements are efficiently retained in mildly to 

strongly reducing sediment. Average interelement ratios of 

several elements in the marine fraction of sediment from 

these areas are comparable and similar to those in average 

plankton. Equally important, minor-element ratios in sediment from all of these environments differ significantly 

from those in the marine fraction of oxic pelagic sediment 

(fig. 5).

REE's are remobilized within sulfate-reducing sediment (Elderfield and Sholkovitz, 1987), an observation in 

agreement with their behavior in sulfate-reducing seawater 

(de Baar and others, 1988; German and others, 1991). Significant loss of REE's from the sediment, however, may not 

occur. Their incorporation into a stable solid phase, such as 

apatite, before the onset of sulfate reduction might enhance 

their retention in the sediment. In sediment on the Peru 

Shelf, pelletal carbonate-fluorapatite accretes in the surface 

and near-surface sediment (Burnett and others, 1988) and 

has a high REE content (Piper and others, 1988). A slightly 

negative Ce anomaly in several, but certainly not all, bulksediment samples (Piper and others, 1988; Dean and Arthur, 

1992), similar to that in apatite pellets (Piper and others, 

1988) and in seawater (de Baar and others, 1985), also 

requires retention of a seawater fraction, possibly within 

very fine grained apatite that is dispersed throughout the 

sediment (Burnett, 1977). Sulfate reduction in the water 

column and in the surface sediment would have prevented 

the retention of REE's in all marine fractions of the sediment, if not their initial accumulation (fig. 4).

This discussion of the behavior of minor elements within 

widely varying redox environments of the modern ocean— 

from seawater through the sea floor to burial—has allowed 

us to introduce a stoichiometric model for the minorelement contents of ancient sediment and, at the same time, 

to outline many of the limitations of this model. Though 

none too brief, our discussion is little more than a cursory 

summary of a vast literature that, even so, has yet to define 

fully this extremely complex environment. Our discussion 

can serve only as an introduction to the subjects of the 

sources of minor elements in marine sediment and of the 

behavior of minor elements during burial. It is surely but 

one small step, hopefully, in the right direction.

RESULTS: ELEMENTAL HOST

PHASES—THE MONTEREY

FORMATION

Rocks of the Monterey Formation consist of the following major components (Isaacs, 1980): biogenic silica (opalA, opal-CT, and diagenetic quartz), calcite, dolomite, organic 

matter, and minor amounts of apatite and metallic sulfides— 

the marine fraction—and quartz, clay, and other Al silicates, 

such as feldspar and heavy minerals—the detrital fraction. 

Their abundances (table 6) were calculated by using the 

normative scheme for which Al2O3x5.7 gives the amount of 

the detrital fraction. Comparison of the contents of other 

major-element oxides with those in WS A defines the contribution of these oxides by the detrital fraction in the Monterey 

Formation. The combination of "excess" SiO2, MgO, and 

P2O5 in each sample identifies the amounts of biogenic 

silica, dolomite, and apatite, respectively. The CaO in
20 GEOCHEMISTRY OF MINOR ELEMENTS IN THE MONTEREY FORMATION, CALIFORNIA

excess of that present in detritus, dolomite (assuming stoichiometric dolomite), and apatite gives the amount of calcite present. The abundance of organic matter is calculated 

from the organic-carbon content (organic matter=organic 

carbonxl.5).

DETRITUS

Fe2O3 , TiO2 , and K2O correlate with A12O3 (table 3). 

On a plot of these elements versus detritus (Al2O3x5.6), the 

trends approximate those of WSA (figs. 6A-6C) and extrapolate to the origin. The agreements are especially close 

when we consider the range of rock compositions used to 

determine the composition of WSA (Wedepohl, 1969-78; 

Medrano and Piper, 1992) and the heterogeneity of the 

Monterey Formation. Several of the plots (fig. 6) suggest 

that the average composition of NASC (Gromet and others, 

1984) more closely approaches that of the detrital fraction of 

the Monterey Formation than does that of WSA. Relative to 

the NASC standard, the Monterey Formation contains a 

slight excess of Fe2O3 . Regardless of the standard used for 

comparison, however, the detrital fraction of the Monterey 

Formation appears to be uniform in composition. More 

analyses of the Rincon Shale and Sisquoc Formation are 

needed to fully evaluate their compositions relative to both 

the Monterey Formation and the two shale standards, but 

the two analyses of each unit suggest no significant differences.

Several minor elements, similar to K2O and TiO2 , correlate strongly with detritus (tables 10, 11). The trends of 

elements versus detritus also approach those of WSA (figs. 

6D-6F) and extrapolate to or near the origin. These elements include Li, Ga, and Co; additional elements that show 

this same strong trend with detritus (tables 10, 11) and with 

WSA are Hf, Sc, and Th (not shown) and the REE's La 

through Eu (figs. 6G-67). The strength of these trends supports our use of WSA as a standard for the detrital host of 

minor elements in the Monterey Formation and our assumption that its composition is uniform. We can use the composition of WSA and the A12O3 content in the Monterey 

Formation to estimate the detrital contribution of minor 

elements to their total inventory, even for those elements 

that do not correlate with detritus, including Cd, Cr, Cu, Mo, 

Ni, Se, U, V, and Zn; we consider below REE's as exceptions to this interpretation.

SULFUR PHASES

Sulfur is present in the Monterey Formation in amounts 

as high as 8 weight percent (table 1) but less than 4 weight 

percent in most samples (Leventhal, 1989; Zaback and Pratt, 

1992). It exhibits a positive correlation with organic matter 

(fig. 7A), similar to the relation in core samples from the 

Santa Maria Basin near Orcutt, Calif. (Leventhal, 1989). A 

slight excess of 0.5 weight percent S at 0 weight percent 

organic matter was reported in samples from the Santa 

Maria Basin, as inferred by extrapolation of the trend of S 

versus organic matter; Leventhal (1989) attributed this excess to the presence of metallic sulfides, mostly pyrite. A 

similar trend is seen in our data (fig. 7A); however, by 

merely interchanging the axes, the curve defining the relation in the samples used in this study extrapolates onto the 

organic-matter axis at 0 weight percent S. Going through 

this same exercise with the data of Leventhal (1989) reduces 

the excess S in samples from the Santa Maria Basin virtually 

to zero, a reflection of the weakness of the correlation, plus 

very low pyrite.

The presence of pyrite was evaluated by comparing 

excess Fe2O3—that is, relative to NASC (fig. 6A)—with 

sulfur. Although the curve for pyrite (fig. IB} defines a 

maximum for excess iron in the Monterey Formation, we 

are unable to say whether pyrite is actually present, although 

certainly it averages less than approximately 1.0 weight 

percent. Pyrite has been reported by researchers investigating the Monterey Formation, and it was observed in several 

of the samples in this study, in the range 1-2 volume percent 

(J. Rullkotter, verbal commun., 1993). Such a low concentration of pyrite likely hosts a minor fraction of minor 

elements.

Ba also correlates weakly with S (fig. 1C; table 10). The 

occurrence of Ba as barite (BaSO4) is more strongly suggested by the much-reduced Ba content in samples analyzed 

by ICP versus those analyzed by NAA (fig. 2C). The lower 

La content in the ICP-analyzed than in the NAA-analyzed 

sample (KG-24, table 2) with the highest Ba content supports this interpretation of barite occurrence; marine barite 

is known to have an REE content of hundreds of parts per 

million (Piper, 1974; Church, 1979; Guichard and others, 

1979). The barite (present in only 0.5 weight percent) and 

apatite in these samples likely represent the major hosts of 

the marine REE inventory.

CARBONATES ORGANIC MATTER

Calcite has negligible contents of minor elements, except Sr (tables 10, 11), as also may be true for dolomite 

(table 11). These conclusions are supported by the sparse 

minor-element content in modern biogenic calcite (Palmer, 

1985).

Several minor elements that do not correlate with detritus correlate strongly with organic matter (table 10), and the 

correlations are enhanced, albeit slightly, by subtracting the 

detrital contribution from their bulk contents (figs. 8, 9). 

Strong partitioning of minor elements into organic matter
RESULTS: ELEMENTAL HOST PHASES—THE MONTEREY FORMATION 21

CM «—

O CO ""> CM LO <—

Nomiw aad siavd NI

'1N3L1NOD ei

NOITIIJM and siwd NI

'1N3LLNOD 3D

INHDHHd 1HOI3M NI 

'1N3LLNOD QA

o°

Nomiw Had siavd NI MNHINOD n

NOmiW HHd SlHVd NI 

'1NH1NOD BO

NOmilM HHd SlHVd NI 

'1N3L1NOD OD

as

ffi 

O

O M

z o «

uo i—

INHCraHd 1HOI3M NI 

'1N3L1NOD EOZ3d

INHDHHd 1HOIHM NI 

'1N3L1NOD OZ5I

00 N. V£> U"> ^ CO OJ rdoodoooo

INHDHHd 1HDI3M NI

'1N3LLNOD Z0!l

>. c "5 o — w

h 03 .> m1) ^ O

5^*0

°^ §

s «„" g

^ « 2

<3 "S ^

•g O 4)

c "c «

5 3 "H,

•O *-; P

8 § i

£ 2 J= :^o §§

il

C C *"•

3 (U JD 

1 §

il

QJ ^^ ~J CJ ^o ® 

- ^ .52

S-^p

"T 2 |

Cy o "J

J | E

^—v "T3 C

551

03 m 4) s> °. 03° -9 (U D

O

60 Ch cQ *—< *"*

4-> >T 1> C ^ C 

O C O [/) C '—3 DO 03
22 GEOCHEMISTRY OF MINOR ELEMENTS IN THE MONTEREY FORMATION, CALIFORNIA 

Table 10. Correlation coefficients for major components and minor elements in the Monterey Formation.

Silica

Detritus — — — —

Apatite — —— --

Organic matter—

Mn— — — — — -

As

Ba— — — — — —

Be— — — — — —

Cd

Ce— — — — — —

Co— ----- — — —

Cr— — — — -

Cu— — — — -----

Ga— — — — — -

TIf

T s

Li——————

Lu

Mo— — - — — —

Nd— — — — -----

Ni

Sc

Sr

Th

U-—— —— — ——

y

Zn— — — — — -

Hf

La——————

Li— — — —

Lu— — — — — —

Mo——————

Nd— — — — — -

Ni—— —— — —

Sc

Se

Sr

Th _ __

U— — —— —— —

Y—— — — — ——

Zn—— ———— —

Silica

1

-.196 

-.276 

-.355

-.321 

-.089

-.221

O7Q

-.065

-.571

-.133

-.172

-.305

-.316

-.200

-.022

-.248

-.055

-.211

-.313

-.065

1 7<

-.143

-.229

-.052

-.146

1 ftfi

-.250

-.335

(17 S

-.235

1 1 n

Hf

.819

.635

noo

QC.fl

.154

.054

QOC

.033

o*)/:

.222

.471

.650

.214

Detritus

1 

-.143 

-.565

C-7Q

.084

.125

.027

.462

.120

.636

.106

.928

.333

.130

.722

.982

.916

001

QQO

.616

.073

Q7C

.210

.039

.920

.053

.901

-.349

.923

.337

.230

642

070

La

.779

.297

.976

.455

.327

"7QC

.321

.984

.921

.744

fiftO

.527

Apatite

1 

204

.371

.592 

.408

-.246

.336

.375

.406

-.126

.517

i so

-.105

-.199

.052

(1Q 1

.152

.437

.516

-.089

.493

.057

f-r*c

.131

.549

.477

.517

Li

1

.467

.159

.791

700

.754

.093

.843

.496

.175

.507

.333

Dolomite

1

-.132

-.341

OQQ

.310

-.447

-.279

-.407

1 f,Q

-.539

-.419

-.341

-.531

C-7Q

-.603

-.466

.263

-.613

-310

-.530

-.296

-.233

-.517

-.346

TQ C

-.540

SQd

-.392

Lu

1

.438

.777

.651

.570

.734 

.555

.541

.572 

.624

.897

f\0f

.721

Calcite

1

.097 

0

-.156

-.150

no a

-.127

-.080

-.574

ns3

0

OQ-7

-.565

-.493

-.479

-.555

OQC

-.469

-.020

-.485

.017

-.463

Qcf:

-.555

1 07

-.153

-.130

-.217

-.102

Mo

1

.214

7QQ

.667

(1QO

on*?

.302

.173 

.103

.753 

.770

.571

.457 

.843

Organic 

matter

1

<Q7

-.256

.665

.443

.491

.116

.333

QQQ

.910

.162

.115 

.016

.357

.177 

.461

7/--T

.951

Q C 1

.063 

.946

.334

7on

.512

.893

Nd

1

.375 

.306

.794 

.248

.979

.899

.584

.394

.712

.454

Sulfur

1

.207 

.407

.084

.372

.771

.439

.160 

.184

.336

.724

.717

7QQ

O<1

QO7

.416

.013

.540

•7/TQ

.735

.722

Ni

.891

.471

.205

. /o /

.899

. /OJ

.676 

.960

Mn

1 

-.163

-.066

-.031 

-.148

rns

.009

-.177

-.033

.066 

.053

-.090

-.054 

-.092

-.131

-.229

-.249

.073 

-.227

-.032

-.177

-.175

-.130

-.213

Sb

1

.072

.917

.347

.055

.115

As

1

.591

C£O

.675

.347

07S

.720

.539

.501 

.342

.543

.516

.717

.509

.720

.761

.849

Sc

1

-.307

.290

.248

.747

.337

Ba

.25

.461

.117

.320

.794

Q/-O

OG*\

.159

.115

.315

.071

.561

.231

.795

.684

.175

.771

.334

.059

.114

C7Q

.740

CQ1

Se

1

.337

.149

.691

.572 

.933

Be

1

OQ7

.671

.751

S47

.365

ir\f\

.480

.693

.439

.348

.455

.270

OQC

.269

.702

.651

OQT

.574

.482

Sm

1

-.277

.891

.472

.774

.547

Cd

.129

.270

.511

.059

.213

.011

.242

Ofifl

.790

Opto

.507

07Q

.139

.51

.249

.144

1 7<

.717

.517

.326

.637

Sr

1

.114

.112

Ce

1

871

.273

.146

.932

070

.933

QOfl

.579

AQ£

.936

.121

.775

.063

.915

TCQ

.984

.456

.274

.606

.262

Th

All

.289

.465

.572 

.273

Co

1

.590

.377

7CQ

.920

.774

.759

.275

QOjr

.473

OQ 1

.929

.300

.899

.843

.515

.465

.705

.796

.521

U

1

.719

.751

.616

QTQ

Cr

1

.916

.411

.371

.217

.519

.355

fO 1

.425

T~Jf.

.403

.894

.536

.312

.770

QOO

QT7

.701

.951

V

1

.636

Cu

1

.32

.166

104

.402

.148

.625

.317

.969

QQ7

1 *\fi

.972

.414

.147

.166

.755

QQO

.733

.633

.951

Y

.919

QCQ

Eu

1

.699

.111

.695

.468

QIC

.174

.720

.351

•3rio

Oft7

<^Cf

.775

295

233

.447

.606

010

400

Yb

.745

Ga

fi"7"7

904

Q7Q

.632

.150

QQQ

.239

.055

.916

.079

.916

.319

.927

.423

.255

CfG

.662

.330

Zn

was also reported by Leventhal (1989) and Odermatt and 

Curiale (1991) for the Monterey Formation and by Swanson 

(1961) and Nissenbaum and Swaine (1976) for other rocks 

and modern sediment. Lewan (1984), Odermatt (1986), and 

Moldowan and others (1986) further examined fractionation 

of metallic elements between the various phases of organic 

matter. The actual slopes of the plots for minor elements and 

organic matter, however, bear no relation to the composition 

of the organic matter in marine plankton.

The different units of the Monterey Formation and the 

Rincon Shale exhibit nearly identical minor-element/organicmatter trends (fig. 8), except possibly for slightly lower 

concentrations of several minor elements in the phosphatic 

shale unit of the Monterey Formation. Mere dilution by 

apatite alone is insufficient to account for these lower concentrations, although more analyses are required to confirm 

the trends. The two samples from the Sisquoc Formation 

contain less than 1.5 weight percent organic matter (table 6) 

and have low minor-element contents; data for these samples 

plot near the origin. Thus, we are unable to evaluate a 

partitioning of minor elements into a marine fraction, possibly organic matter, in these two samples.
RESULTS: ELEMENTAL HOST PHASES—THE MONTEREY FORMATION 23

Table 11. Factor analysis for major components in sedimentary rocks of the Monterey Formation, 

using the computer program StatView II (oblique-solution primary-pattern matrix).

^ilii-Q

Dolomite ————

C*a}r\t(*

Organic matter — 

Sulfur

Mn

Ba— - —— - ——— - 

Be-— ————— - 

Br ________

Qj ________ __ __ .

Ce_ ________

Q) _____

Q- _____ __ _______

Cu_ ___

£u._ ______ _

Ga

Hf— — ————— -

La

Li

Lu

Mo-—— _____ - 

Nd

NJ _ __ ___ _

Sb _____ . ____

§c_. _____ ____

§e __________

sm __________

SrTT.

u— - — - —

y

Y

Yb ________ 

Zn— ——— - ———

Factor 1

-0.133 

-.054 

.348 

-.127 

-.063 

.874 

.928 

-.090 

.599 

.882 

.117 

.186 

.382 

-.039 

.217 

.855 

.992 

.277 

-.035 

-.029 

.225

.584 

.790 

.148 

.942 

.966 

.021 

.999

.254 

ni£

-.027 

.619 

.929 

.623 

.561 

.902

Factor 2

-0.147 

.976 

-.074 

-.662 

-.371 

.005 

.050 

-.023 

.395 

-.021 

.685 

.163 

.028 

.929 

.889 

.261 

.016 

.759 

.958 

.917 

.891 

.848 

.646 

-.074 

.909 

.119 

-.042 

.926 

-.073 

.913

.913 

.289 

.104 

.551 

.680 

.184

Factor 3

-0.108 

-.065 

.586 

-.424 

.827 

.129 

.013 

-.138 

.163 

-.123 

.355 

.185 

-.013 

-.157 

.074 

.084

09 Q

.029 

-.075 

-.089 

-.062 

-.024

.031 

-.070 

-.052

.071 

-.095 

.057 

-.048 

-.024 

.914 

-.138 

.000 

-.177

.234 

.125 

.026

Factor 4

-0.843 

.017 

.067 

.585 

-.187 

.066 

.037 

.664 

.042 

.006 

.279 

-.015 

-.081 

-.047 

.120 

.117 

.012 

.070

.089 

-.076

.056 

-.061

-.102 

-.091 

.018 

-.088 

.059 

.012 

-.047 

.022

.007 

.053 

noB

.025 

-.058 

.036

Factor 5

-0.231 

.033 

.026 

-.061 

-.077 

.331 

.303

T1 fi

-.292 

-.073 

.222 

.897 

-.173 

.222 

046

.026 

.087 

.299

.001 

-.055 

.129 

.149 

.313

-.112 

.061 

.133 

.162 

-.285 

.127 

.005 

.141 

.306 

.195 

.125 

-.190 

-.276 

-.025

Factor 6

-0.082 

.017 

.252 

.127 

-.225 

-.013 

-.170

-.217

.298 

.001 

.194 

-.167 

.779 

.056

Of.8

.042 

.031

-.326 

.115 

-.150 

.024 

.339 

-.196

.332 

.026 

-.044 

-.152 

-.029 

-.034 

-.022 

.012 

.050 

.404 

-.020

-.008 

-.156 

.125

For the samples from the Monterey Formation alone, 

those from the Lions Head section have slightly higher 

ratios of Cr, Cu, Se, V, and Zn to organic matter than those 

from the Naples Beach section (fig. 9). We can attach no 

significance to these differences, given the number of samples 

we examined and the magnitude of the differences.

APATITE

On a plot of the marine fraction of heavy metals against 

apatite (fig. 10), the samples follow two trends, a relation 

suggested by the organic-matter plots (fig. 8). The first trend 

is defined by the minimum of the plot of minor elements 

versus organic matter (curves labeled "organic matter," 

fig. 9). This trend was plotted in figure 10 by converting 

organic-matter to P content, on the basis of the C:P ratio in 

plankton of 0.019 to 0.0225 (Collier and Edmond, 1984; 

Brumsack, 1986), and then converting P to apatite content 

by assuming 17.7 weight percent P in apatite (table 5). The

success of this calculation in defining the organic-matter 

trend, particularly for Cr, Cu, Ni, and Zn, suggests that 

much of the P in excess of the detrital contribution might be 

organically bound, even though we have expressed it in 

figure 10 as an apatite equivalent. The second trend, referred 

to as the apatite trend (curves labeled "apatite," fig. 10), 

identifies samples with reduced minor-element contents. 

These same relations have been observed for the San Gregorio 

Formation (Piper, 1991), aphosphatic deposit of Oligocene 

to Miocene age in Baja California.

The degree of minor-element enrichment between these 

two trends, expressed by the relation

[metal/P] apatite :[metal/P]organic matter, (7)

is surprisingly similar for all minor elements; it varies over 

the limited range 0.16 (Cd)-0.22 (Cr). Although it is tempting to conclude that minor elements are incorporated into
24 GEOCHEMISTRY OF MINOR ELEMENTS IN THE MONTEREY FORMATION, CALIFORNIA

these two major phases, organic matter and apatite, they also 

are probably present in minor phases, such as metallic 

sulfides. Otherwise, we might have expected such an element as Cd, similar in ionic charge and radius to Ca2+, to be 

the most strongly enriched of the minor elements in the 

phosphatic samples. If anything, the opposite is true: The 

ratio

20

H

In

ZZ15

88

ir

o 

o

2.5

[Cd/P]apatite :[Cd/PJorganic matter (8)

"0 1

H

i 1.

. 1

4

4

)

I 0.5

I

0 

-0.5

0

3000

2500

2000 

Z W 1 500

, 1000

500

012345678 

S CONTENT, IN WEIGHT PERCENT

Figure 7. Organic-carbon content (A), Fe2O3 content in excess of 

a detrital contribution (B), and Ba content (C) versus S content in 

sedimentary rocks of the Monterey Formation. Two curves in 1A 

are best-fit lines, obtained by interchanging axes; they have same 

standard deviation (S.D.) of 0.65 and center of mass. S.D. of curve 

in figure 1C is 0.80.

is smaller than those for other minor elements, which should 

substitute less strongly into the apatite phase.

The REE patterns (fig. 11) of the samples indicate that 

REE's are present in excess of a detrital contribution, despite strong correlations of individual REE's with detritus 

(fig. 6; table 11). The depletion of Ce relative to La and Nd 

in most samples, and a heavy-REE enrichment in several 

samples (for example, 2, 17, 22, 24, fig. 11), resemble the 

REE pattern of seawater (Goldberg and others, 1963; 

H0gdahl, 1967; de Baar and others, 1985). This pattern, 

which is unique to the marine environment, represents unequivocal evidence of a marine origin for some of the REE's 

in the Monterey Formation. Although apatite is known to 

host REE's in phosphate deposits (Altschuler and others, 

1967; McArthur and Walsh, 1984; Wright and others, 1987; 

Piper, 1988, 1991; Piper and Medrano, 1991) and in modern 

sediment (Piper and others, 1988), its low content in these 

samples, the low content of REE's in the marine fraction of 

sediment, and the likely partitioning of some of this fraction 

in barite preclude our ascertaining the importance of apatite 

as REE host in the Monterey Formation.

An Eu anomaly exhibited by several samples (fig. 11) is 

possible further evidence of a marine fraction of REE's. 

Plots of this Eu anomaly against major components and 

minor elements, however, give no clue as to a possible phase 

that might be responsible for its occurrence.

Apparently, the REE contents in WSA overestimate the 

detrital contribution of REE's to the Monterey Formation. 

NASC also might not be totally representative of the detrital 

fraction. Although it defines a minimum for La and Yb 

contents (fig. 6G), a Ce content even lower than that in 

NASC (fig. 6H) is needed to define the minimum detrital Ce 

content. Using these minimums for the REE content in 

detritus—for La (31 ppm), Ce (61 ppm), and Nd (29 ppm)— 

we can calculate the REE content and Ce anomaly in the 

marine fraction alone (fig. 12). The Ce anomaly correlates, 

albeit weakly, with apatite, and the correlation is stronger 

than that between apatite and the Ce anomaly calculated by 

using bulk REE contents. Given the large error in this calculation due to the dominance of the detrital contribution to 

the light-REE inventory (figs. 6G, 6//), the improvement in 

the apatite trend is rather remarkable and seems to support 

our method of selecting Ce, La, and Nd contents in the 

detrital fraction of the Monterey Formation.

U correlates with organic matter (fig. 8) and weakly 

with apatite (tables 10, 11).
35

Z 30

O 

-3

zw O ft,

ft. 10

Z

5

0

400

350

Z

O 300

!pj 200

oS 100

Z

~ 50

0

I

200

EXPLANATION 

x Sisquoc Formation 

+ Rincon Shale

Monterey Formation: 

n Clay-shale 

o Phosphatic shale 

o Clayey porcelanite (upper part) 

A Calcareous porcelanite (lower |

50

10

Clay-shale

10

10

100

O 80

Uoo

20

15 20 25

15 20 25

Phosphatic shale

shale/

y-shale

350

Z 300

O

f_rd 250

S« 200

u£ 150

ft. 100

Z

50

0

I

60

50

20

10

15 20 25

Siliceous shale/ 

Clay-shale

25

O20

El

C iv

Zu

15

10 15 20 25 

Siliceous shale/ 

Clay-shale

10 15 20 25

600

O 5°°

J

Z*§ 400 

Z E 300

> < 200 

ft. 

Z

TM 100

0

Cla

Siliceous

Clay

500

§ 400

300

8^ 200

£ 100

ORGANIC-MATTER CONTENT, IN WEIGHT PERCENT

0 5 10 15 20 25 

ORGANIC-MATTER CONTENT, IN WEIGHT PERCENT

ORGANIC-MATT

Figure 8. Contents of Cd (A), Cr (B), Cu (Q, Mo (D), Ni (£), Se (F), U (G), V (//), and Zn (/) versus organic-matter content of marine fraction 

Formation. Curves, which represent grouping of samples by lithology, are fitted to data visually.
EXPLANATION 

Sisquoc Formation,

Naples Beach 

Rincon Shale,

Naples Beach 

Monterey Formation

Naples Beach

Lions Head

10 15 20 25

ORGANIC-MATTER CONTENT, IN WEIGHT PERCENT

0 5 10 15 20 25 

ORGANIC-MATTER CONTENT, IN WEIGHT PERCENT ORGANIC-MATT

Figure 9. Contents of Cd (A), Cr (fi), Cu (C), Mo (D), Ni (E), Se (F), U (G), V (//), and Zn (/) versus organic-matter content of marine fraction i

Formation. Samples are grouped by site. Curves labeled "plankton" are based on minor-element content of marine organic matter (Martin and K

1984; Collier and Edmond, 1984; Cutter and Bruland, 1984). Curves labeled "organic matter" represent our estimate of best minimum value for 

matter in the Monterey Formation.
EXPLANATION 

Monterey Formation: 

Lion's Head 

Naples Beach 

Rincon Shale, 

Naples Beach 

Sisquoc Formation, 

Naples Beach

'••'.'/ Organic matter

I "300

O

APATITE CONTENT, IN WEIGHT PERCENT

02468

APATITE CONTENT, IN WEIGHT PERCENT

0 2 

APATITE 

Figure 10. Contents of Cd (A), Cr (B), Cu (Q, Mo (D), Ni (£), Se (F), U (G), V (//), and Zn (/) versus apatite content of marine fraction 

Formation. Curve labeled "apatite" is fitted to data visually; dotted area between curves labeled "organic matter" is based on curve label

converting organic-matter to P-equivalent content (P:C ratio of 0.019-0.0225 in organic matter) and P-equivalent to apatite-equivalent conten
28 GEOCHEMISTRY OF MINOR ELEMENTS IN THE MONTEREY FORMATION, CALIFORNIA 

MISCELLANEOUS

Several sample pairs, representing associated finely laminated versus massive units, were included in the samples 

analyzed (Isaacs and others, 1992). Although each massive 

unit has a higher metallic-element content within the marine 

fraction than its laminated pair (fig. 13), both plot close to a 

single organic-matter trend.

DISCUSSION: ELEMENTAL SOURCES— 

THE MONTEREY OCEAN

Two slightly different approaches to the partitioning of 

minor elements between multiple marine sources offer a 

possible check on our determination of elemental sources to 

the Monterey Formation. Both approaches assume that the 

detrital fraction has a uniform composition comparable to

i.o

§

\

0.1

i.o

LaCe Nd Sm Eu Gd YbLu

10

0.1

LaCe Nd Sm Eu Gd YbLu

1.0

0.1

LaCe Nd Sm Eu Gd

RARE-EARTH ELEMENTS

YbLu

0.1

LaCe Nd Sm Eu Gd YbLu

1.0

0.1

LaCe Nd Sm Eu Gd YbLu

1.0

0.1

LaCe Nd Sm Eu Gd

RARE-EARTH ELEMENTS

YbLu

Figure 11. Rare-earth-element patterns for samples from the Monterey Formation. A, Sisquoc Formation. B, 

Siliceous shale (upper part). C, Phosphatic shale. D, Clay-shale. E, Siliceous shale (lower part). F, Rincon Shale. 

Patterns represent elemental contents normalized on an element-by-element basis to World Shale Average (Wedepohl, 

1969-78; Piper, 1974) and plotted against atomic number. Normalizing values (in parts per million): La, 41; Ce, 83; 

Nd, 38; Sm, 7.5; Eu, 1.61; Yb, 3.53; and Lu, 0.61. Samples are grouped according to lithology, as in figure 8. 

Although data for Gd are unavailable, curves are drawn through a Gd value estimated by interpolation between Sm 

and Yb values. Purpose of interpolation is to emphasize anomalous behavior of Eu; however, we have made no 

attempt to evaluate Eu anomaly without actual Gd data.
DISCUSSION: ELEMENTAL SOURCES—THE MONTEREY OCEAN 29

that of some sedimentary-rock standard. The first approach 

computes the rate of accumulation of each element in the 

marine fraction by using the rate of accumulation of the 

rocks, which is determined by one of various methods. By

10

g

H 3

z 2

0.5

* -°- 5 

u 

U

- 1

-1.5

-2

0

-0.05

-0.1

* -0.15 

u 

U

-0.2

-0.25

-0.3

-0.350 2 4 6 8 10 

APATITE CONTENT, IN WEIGHT PERCENT

Figure 12. La content (A) and Ce anomaly (fi) of marine fraction, 

and Ce anomaly in bulk sediment (Q, versus apatite content in 

sedimentary rocks of the Monterey Formation. Curves in figure 

12A represent apparent trends; curves in figures 12B and 12C are 

least-squares best-fit lines, with standard deviations of 0.65 (fig. 

125) and 0.54 (fig. 12C)

assuming a minor-element stoichiometry for Miocene organic matter, based on the minor-element content of modern 

plankton, the rate of accumulation of organic matter required to supply each minor element to the Miocene sea 

floor can be calculated. These values are compared with the 

rate of accumulation of organic matter on the sea floor of the 

modern ocean. Those elements that give higher rates than 

probable organic fluxes are interpreted to have accumulated 

directly from seawater as a hydrogenous fraction, in addition to having accumulated as a biogenic fraction. Their rate 

of accumulation within the hydrogenous fraction depends 

on such factors as water-column advection, metallic-element concentrations in seawater, and bottom-water redox 

conditions; and their rate of accumulation within the biogenic fraction depends mostly on primary productivity in 

the photic zone.

The varying rate of accumulation of sediment in the 

Monterey Formation (Isaacs, 1985) and the small number of 

samples analyzed in this study, alone, dissuaded us initially 

from emphasizing this first approach. However, the range of 

concentrations and average values measured in these samples 

agree closely with those of cored (max 3,320 m deep) rock 

samples from the Santa Maria Basin (Leventhal, 1989) and 

35 additional surface samples from the Santa BarbaraVentura Basin (C.M. Isaacs, unpub. data, 1993). Also, ratios 

of the major-element oxides and minor elements to A12O3 in 

the detrital fraction and minor-element:minor-element ratios in the marine fraction are virtually identical in the three 

sets of samples. Agreement with the Santa Maria Basin 

samples further precludes major alteration by surficial weathering of the rocks examined in this study.

The second approach compares the relative contents of 

minor elements in the marine fraction of the rocks with their 

contents in modern plankton. This approach is greatly facilitated when the minor elements exhibit strong interelement

400

350

2

9, 300

z*5s 25°

ZW 200 

j^H 150

0- 100

2" 50

Phosphatic shale

Clay-shale

11-10

0 5 10 15 20 25 

ORGANIC-MATTER CONTENT, IN WEIGHT PERCENT

Figure 13. Cr versus organic-matter content of marine fraction in 

sedimentary rocks of the Monterey Formation (see fig. 8fi). 

Numbered data points represent closely associated, finely 

laminated/massive sample pairs (see fig. 1 for locations).
30 GEOCHEMISTRY OF MINOR ELEMENTS IN THE MONTEREY FORMATION, CALIFORNIA

correlations. From simple x-y plots, minor-element:minorelement ratios give the elements that are enriched above a 

biogenic contribution. This procedure, which is used in the 

absence of information on sediment-accumulation rates, 

points up the desirability of a master variable, or a single 

element, that defines the marine organic source, just as 

A12O3 defines the terrigenous source. In this discussion, we 

resorted to using Cu as the master variable for the marine 

biogenic fraction. Several aspects of its chemistry recommend it.

1. It is a bioreactive element, with a concentration in plankton (table 5) that exceeds those of most other bioreactive 

minor elements (Martin and Knauer, 1973; Broecker and 

Peng, 1982; Bruland, 1983; Collier and Edmond, 1984; 

Brumsack, 1986). Thus, its biogenic signal should be 

strongly imprinted in rocks that were initially rich in 

organic matter.

2. Although it accumulates from oxic seawater (fig. 5) by a 

small fraction of its dissolved load being adsorbed onto 

other particulate matter (Boyle and others, 1977), more 

importantly, it precipitates under seawater sulfate-reducing conditions as a sulfide (Jacobs and others, 1985) 

virtually quantitatively. Its concentration in seawater 

should make this hydrogenous input to any sediment 

distinguishable from a biogenic or a detrital input. If we 

assume redox and advection conditions similar to those 

in the Cariaco Trench (Jacobs and others, 1987); a Cu 

concentration in seawater advecting into the basin equal 

to that of seawater at 2,000-m depth (table 8), and a bulksediment-accumulation rate of 3 mg/cm2 per year, similar to that of the Monterey Formation in this area (Isaacs,

1985), then the content of Cu, which would have precipitated as a sulfide, would be approximately 30 ppm.

3. The organic-matter content of the Monterey Formation 

(table 6) is similar to that of surface and near-surface 

sediment accumulating currently on the Peru Shelf, in 

which sulfate-reducing conditions in the sediment pore 

water extend close to the benthic boundary layer in many 

areas (Froelich and others, 1988). Although Cu is quickly 

recycled into the overlying water under oxic conditions 

(Boyle and others, 1977; Fischer and others, 1986), it 

should be retained under sulfate-reducing conditions, 

owing to the low solubility of Cu2S, as reflected by its 

precipitation under seawater sulfate-reducing conditions 

(table 9; Jacobs and others, 1985) and the immobility of 

Cu in sulfate-reducing sediment (Douglas and others,

1986).

4. The marine fractions of most minor elements in the 

Monterey Formation correlate strongly with Cu (fig. 14; 

table 10), allowing a precise comparison of the minorelement contents through simple x-y plots. The absence 

of such correlations, however, does not preclude the use 

of this approach, inasmuch as the strength of present 

correlations should depend more on the composition of 

host phases than of source phases. The compositions of

the host phases likely reflect diagenetic processes and 

(or) recent rock alteration, rather than depositional processes. For those minor elements for which such correlations are weak, more samples must be analyzed to fully 

document the interelement ratios.

We should add that both approaches are stoichiometric. 

They assume that the composition of detritus was the same 

as that of standard shale (WSA or NASC), the composition 

of deposited organic matter was the same as that of modern 

organic matter, and the metallic-element content in excess 

of these two sources is attributable to a hydrogenous source.

TERRIGENOUS SOURCE

Ratios of major-element oxides to detritus strongly indicate that the detrital fraction in the Monterey Formation 

has a uniform composition in the two sections sampled. 

They furthermore indicate that the detrital fraction had a 

predominantly terrigenous source, as opposed to a marine 

volcaniclastic source. Plots of the detrital fraction 

(5.6xAl2O3 ) versus TiO2 and K2O (figs. 65, 6Q fall along 

single trends, have slopes approaching those for WSA, and 

extrapolate to zero. Thus, this fraction is both a current host 

phase and a source phase.

This interpretation extends to several minor elements. 

The Co:A12O3 ratio in WSA is 1.13X10"4, virtually the same 

as in the Monterey Formation (fig. 6F). The scatter of the 

data about the WSA line likely reflects uncertainties in the 

analytical procedures at low Co contents (table 4), rather 

than significant deviations in the Co content of any sample. 

This same relation extends to Li and Ga (fig. 6) and to Hf, 

Sc, and Th (table 10). Extrapolation of the curves to zero 

also supports the conclusion that the detrital fraction is the 

sole source of these minor elements. These relations support 

our use of WSA as a representative of the detrital source of 

the other minor elements under consideration, except REE's.

For those minor elements that correlate with organic 

matter (figs. 8,9), their bulk content in most samples is large 

relative their content in the detrital fraction. Thus, a slight 

error in our estimate of the detrital contribution, based on 

the minor-element content in WSA and the A12O3 content in 

the Monterey Formation samples, introduces a small error in 

our calculation of the marine fraction of minor elements.

MARINE SOURCE

Strong correlations between many minor elements (fig. 

14; tables 10, 11) and the similarity in the partitioning of all 

minor elements into the organic-matter and apatite trends 

(fig. 10) suggest that the minor elements have undergone 

only limited remobilization since their initial accumulation 

on the sea floor. Adsorption onto residual organic matter, 

apatite, and, possibly, sulfide precipitates within the fine
DISCUSSION: ELEMENTAL SOURCES—THE MONTEREY OCEAN 31

35

§ 30

-•325

"

U £ 15 s*

o. 10 2

5

0

400

350

300

§£200

£l 150 

^100

M

50

0

100

O 80

60

220

350

2 300 O

Hid 25 °

M 2

20°

Sea water

EXPLANATION 

Stsquoc Formation,

Naples Beach 

Rincon Shale,

Naples Beach 

Monterey Formation,

Naples Beach 

Monterey Formation,

Lions Head

50 100 150 200

60

2 50

O

40

£30

O 20

J

Plankton x 1.5, o

Seawater

50 100 150 200

50 100 150 200 50 100 150 200

Plankton

50 100 150 200 100 150 200

2*

100

50

0

Plankton

500

O 400

300

200

100

0.35

50 100 150 

Cu CONTENT, IN PARTS PER MILLION

200 50 100 150 

Cu CONTENT, IN PARTS PER MILLION

200

Figure 14. Contents of Cd (A), Cr (B), Mo (Q, Ni (D), Se (E), U (F), V (G), and Zn (tf) versus Cu content of marine 

fraction in sedimentary rocks of the Monterey Formation. Samples are grouped by site. Curve labeled "plankton" 

represents our best estimate of trend for modern plankton, extrapolated into field of the Monterey Formation; curve 

labeled "seawater" represents ratio for seawater (table 8), also extrapolated into field of the Monterey Formation; 

curve labeled "planktonx..." represents data for the Monterey Formation, along with its deviation from plankton.
32 GEOCHEMISTRY OF MINOR ELEMENTS IN THE MONTEREY FORMATION, CALIFORNIA

unconsolidated sediment apparently removed minor elements 

from pore water as they were released during diagenesis 

from the labile fraction of organic matter and any labile 

hydrogenous fractions.

Although the marine fraction of several minor elements 

correlates strongly with organic matter (fig. 8), a curve that 

defines the approximate average minimum minor-element 

content in organic matter (curves labeled "organic matter," 

fig. 9) lies well above that for modern plankton in all cases, 

by approximately 3- to 300-fold. If the sedimenting organic 

matter had the same stoichiometry as modern plankton, then 

clearly a major readjustment to the minor-element:organiccarbon ratio occurred during sedimentation and burial. Depth 

profiles of organic carbon in modern sediment (Douglas and 

others, 1986; Froelich and others, 1988; Calvert, 1990), 

which has an organic-matter content similar to that of the 

Monterey Formation, strongly suggest that some organic 

matter was lost during early diagenesis as HCO^, rather than 

that minor elements were gained. Possible exceptions are 

Cr, Mo, U, and V, which might have diffused across the 

benthic boundary layer (Brumsack, 1983; Frangois, 1988; 

Emerson and Huested, 1991).

Sediment-trap studies of pelagic environments further 

support the loss of organic matter during early diagenesis 

(Fischer and others, 1986). Settling particulate matter collected at greater than 3,000-m depth contains approximately 

5 times more organic matter than detritus, whereas surface 

sediment at the same sites contains approximately 100 times 

more detritus than organic matter. Approximately 95 to 99 

percent of the organic matter that rains out of the water 

column is, thus, oxidized at and very near the surface. 

Ocean-margin areas will have an even larger flux of organic 

matter to the sea floor, owing to shallower sea floor (Sarnthein 

and others, 1988), higher primary productivity (Berger and 

others, 1988; Pedersen and Calvert, 1990), and a positive 

relation between the relative rain rate of organic matter from 

the photic zone and primary productivity (Baines and others, 1994).

To differentiate between minor-element contributions 

to the Monterey Formation by (1) a biogenic source and (2) 

a hydrogenous source, we first ascertain the biogenic contribution. The minor-element contribution by organic matter 

(plankton) alone can be evaluated by comparing the rate of 

accumulation of organic matter necessary to deliver the 

now-observed metallic-element contents in the Monterey 

Formation with modern sedimentary environments. The rate 

of primary productivity of organic matter in the photic zone 

of the Peru Shelf today, an area of exceptionally high primary productivity, is approximately 200 mg/cm2 per year 

(Chavez and Barber, 1987), of which approximately 15 to 

45 percent settles out of the photic zone (Dugdale and 

Goering, 1970; Von Bockel, 1981). As much as 8 percent 

escapes oxidation in the water column and benthic boundary 

layer altogether and accumulates within the sediment 

(Reimers and Suess, 1983). An even larger amount must

settle (that is, rain) onto the sea floor, as is the case in the 

pelagic environment (Fischer and others, 1986; Sarnthein 

and others, 1988). For the Monterey Formation, Isaacs (1985) 

estimated a bulk-sediment-accumulation rate of 3 to 5 mg/ 

cm2 per year, although this rate varied spatially and temporally. By considering that (1) the average Cu content in the 

marine fraction of the Monterey Formation is 37 ppm (fig. 

14) and (2) the stoichiometry of accumulating organic matter was the same as that of modern plankton (table 5), we 

calculate the rate of accumulation of organic matter required 

to deliver Cu to the sea floor at 10 to 15 mg/cm2 per year. A 

calculation based on the Fe content (fig. IB) in excess of the 

terrigenous contribution (NASC curve, fig. 6A) and the Fe 

content of plankton (table 5) gives a similar accumulation 

rate for organic matter. Cd and Zn require slightly lower 

rates, and Mo and Se slightly higher rates. Thus, the sediment raining onto the sea floor consisted of approximately 

80 percent organic matter. Our interpretation is that primary 

productivity significantly lower than the current rate on the 

Peru Shelf could have provided this amount and the total 

marine fraction of Cu, Cd, Mo, Se, Zn, and Fe to the Monterey 

sea floor.

If the sole source of these minor elements was organic 

matter and minor elements were retained in the sediment 

after deposition, then a projection of the interelement ratio 

for any pair of minor elements in plankton should extend 

into the field of concentrations for the Monterey Formation. 

In fact, all the values are displaced slightly from the minorelement:Cu trend of plankton (fig. 14). The shift in trends 

away from the ratios in plankton is toward the seawaterconcentration ratios, suggesting that a small part of the 

marine fraction may be attributable to the accumulation of a 

hydrogenous fraction.

Unlike the Cd:Cu, Mo:Cu, Se:Cu, Zn:Cu, and Fe:Cu 

trends, the shifts in minor-element:Cu trends for Cr, V, 

REE's (not shown), and U away from the organic-matter 

trends are extreme and must be explained largely by inorganic processes. For Cr, U, and V, their diffusion across the 

benthic boundary layer into a pore-water system that was O2 

depleted offers one possible explanation (Brumsack and 

Gieskes, 1983; Brumsack, 1986; Emerson and Huested, 

1991; Klinkhammer and Palmer, 1991). This same explanation might also account for the slight enrichment of Mo 

relative to Cu (fig. 14). All else being equal, we might have 

expected the order of enrichment in the rocks to reflect, in 

part, their sea water concentrations: Mo»U>V»Cr; but 

this is not the case. In absolute terms, V is somewhat more 

enriched in rocks of the Monterey Formation than is Cr, and 

both elements are much more strongly enriched than are Mo 

and U (fig. 8). Their enrichments, over and above a biogenic 

contribution and relative to their seawater concentrations, 

follow the trend Cr>V»U«Mo.

The thermodynamic properties of these elements (table 

9) allow Cr and V to precipitate under conditions of denitrification in the OMZ of the water column, as well as under
DISCUSSION: ELEMENTAL SOURCES—THE MONTEREY OCEAN 33

lower redox conditions, but these same properties restrict 

Mo precipitation to sulfate-reducing conditions. Thus, bottom-water conditions of denitrification can explain the much 

greater enrichments of Cr and V. These two metallic elements would have been strongly enriched in sediment underlying such an OMZ, more so than other minor elements, 

by precipitation as oxyhydroxides and (or) adsorption onto 

particulate phases within seawater, but unlikely by diffusion 

across the benthic boundary layer. The absence of a strong 

enrichment of U apparently is due to its occurrence in seawater as UO2(CO3)f-, rather than as UO2(CO3)^-. The slight 

Mo enrichment probably reflects diffusion across the benthic 

boundary layer, but we cannot dismiss the possibility of 

brief periods of sulfate reduction in the bottom water, as 

occur on the Peru Shelf (Dugdale and others, 1977).

Establishment of denitrification in the bottom water 

constrains bottom-water advection. If we assume that the 

denitrifying part of the water column was 250 m thick and 

that approximately 25 percent of surface productivity was 

oxidized in the bottom water—conditions similar to those 

on the Peru Shelf today—a residence time for the bottom 

water of approximately 5 yr would be required to establish 

denitrification. Although this value will change by adjusting 

the various parameters, the instability of the water column 

of the present-day Santa Barbara Basin (Sholkovitz and 

Gieskes, 1971) clearly suggests a residence time in this 

modern, open-oceanic, denitrifying basin on the order of 

years. This calculation should apply to "bottom" waters, 

whether we are considering a basin environment or an openshelf environment, as illustrated in figure 3.

The Cr content of the Monterey Formation also limits 

the residence time of the bottom water at the time of deposition. Assuming that (1) the thickness of denitrifying water 

was 250 m, as above; (2) the initial Cr concentration in the 

water advecting into the basin was 0.21 ppb (table 8), 25 

percent of which was removed to the sea floor, the approximate maximum amount of Cr(III) in the OMZ of the eastern 

Pacific Ocean (Murray and others, 1983); (3) the average Cr 

content in the marine fraction of the Monterey Formation 

is 102 ppm, 90 percent of which accumulated as a hydrogenous fraction (fig. 8); and (4) the sediment-accumulation 

rate was 3 mg/cm2 per year (Isaacs, 1985), then the maximum residence time for bottom water in the basin is also 

calculated at 5 yr. Adjusting the thickness of the denitrifying 

section of the water column changes the residence time 

proportionally but does not alter the agreement between 

the calculation based on the accumulation of Cr and the 

above calculation of the oxidation of organic matter. Although this calculation is simplistic, the result is consistent 

with our interpretation of bottom-water denitrification.

The residence time for bottom waters in permanently 

sulfate reducing basins is considerably greater than this: in 

the Black Sea about 375 to 1,000 yr (Ostlund, 1974; Murray 

and others, 1991) and in the Cariaco Trench 100 to 200 yr 

(Jacobs and others, 1987). Although sulfate reduction in the

bottom waters of such fiords as Saanich Inlet can be seasonal (Anderson and Devol, 1973), several aspects of these 

small inland basins suggest that they are unlikely to be 

analogs of a large, open-ocean basin. For example, much of 

the organic matter settling into the bottom water might be 

terrigenous rather than marine, forcing sulfate reduction at 

a much greater rate than that predicted by surface-water 

productivity alone. Also, flushing apparently reestablishes 

denitrification, rather than oxygen respiration, in the bottom water of Saanich Inlet. Thus, the mean residence time 

of the bottom water is more than merely 1 yr, and the water 

is poised to almost immediately reestablish sulfate reduction 

with the secession of flushing. Although we cannot dismiss 

the dynamics of this basin as one possible explanation, the 

longer bottom-water residence time required for the establishment of sulfate reduction in such larger basins as the 

Black Sea, and the significantly shorter residence time for 

bottom water of the Miocene basin (or open shelf), seems to 

preclude sulfate reduction in the bottom water of the Santa 

Barbara-Ventura Basin during Miocene time.

Field studies of REE's have established their removal 

from denitrifying seawater and their dissolution under conditions of sulfate reduction (de Baar and others, 1988; German and others, 1991). Sulfate reduction in the bottom 

water would have required sulfate reduction in the pore 

water of the surface sediment as well. Such a system should 

have precluded any enrichment of REE's above a detrital 

contribution, and yet REE's are enriched in the sediment, 

although this conclusion is based more on the seawater-type 

pattern of several samples (fig. 11) than on their absolute 

contents (fig. 6). Nonetheless, denitrification in the bottom 

water and sulfate reduction restricted to the near-surface 

pore water could have allowed the accumulation of REE's 

from the water column. The content of marine La (fig. 12A) 

supports this interpretation: Its content in the marine fraction of the Monterey Formation and its content in seawater 

(table 8) give a bottom-water residence time of 5 yr, the 

same as did Cr. Thus, REE's should have been no more 

enriched than by the slight amount we observe.

Scavenging of additional minor elements in the water 

column, particularly Th, Sc, Be, Ga, and Hf, by particulate 

phases is clearly an important process on a global scale (Li, 

1981; Balistrieri and Murray, 1984; Clegg and Sarmiento, 

1989). The mere absence of these elements in the marine 

fraction of the Monterey Formation, however, may not allow us to dismiss scavenging as an important minor-element-enrichment mechanism in the Monterey Formation. 

The low concentrations of Th and other elements of this 

group in seawater should preclude our identification of a 

hydrogenous fraction within bulk analyses. Leaching experiments, which we have not pursued to date, might identify such a fraction.

Although Cd, Cu, Ni, and Zn are slightly enriched 

above their biogenic input, scavenging cannot explain the 

slight shifts in minor-element:Cu ratios toward their values
34 GEOCHEMISTRY OF MINOR ELEMENTS IN THE MONTEREY FORMATION, CALIFORNIA

in seawater (fig. 14). Ni should be only weakly scavenged 

from seawater, whereas Cu and Zn should be scavenged 

more efficiently (Clegg and Sarmiento, 1989); yet Ni is the 

more strongly enriched above a biogenic source. Also, 

scavenging should have shifted the Zn:Cd ratio away from 

the stoichiometric value in organic matter of about 9.2 (table 

5), which is not observed (compare figs. 14A and 15 with 

fig. 14H). Evidence against scavenging is also provided by 

the metallic-element content of fecal material (table 7). Its 

high Cd, Cu, and Zn contents indicate these minor elements 

are strongly scavenged by fecal debris, but an Ni:Fe ratio 

approximating that in WSA suggests a detrital origin for Ni 

(Piper, 1991). The low organic-carbon content (approx 5 

weight percent; Youngbluth and others, 1989), and high 

clay content (approx 85 weight percent; Dunbar and Berger, 

1981) in fecal material emphasize the need for a complete 

chemical analysis to fully account for the partitioning of 

metallic elements between the various fractions of fecal 

material. Even in the absence of such data, the enrichment 

of Ni in the Monterey Formation over both Zn and Cu is 

evidence against a major role for seawater scavenging in the 

enrichment of minor elements in these rocks.

Accumulation within biogenic silica, in addition to organic matter, might account for the displacement of these 

minor-element ratios away from the plankton value. The 

enrichment of Zn in biogenic silica is supported by the 

similarity of the distribution of Zn in seawater to that of 

Si(OH)4 (Sclater and others, 1976). Analyses of biogenic 

silica (Martin and Knauer, 1973), however, show that Cu is 

even more enriched in this phase, which has a Zn:Cu ratio of 

about 0.7. Accumulation of this phase on the sea floor, then, 

followed by its dissolution and the retention of Cu and Zn 

could explain the shift in the Zn:Cu trend in the rocks away

s

u1

35

30

25

15

10

5

0

Phosphatic 

shale

50 100 150 

Cu CONTENT, IN PARTS PER MILLION

200

Figure 15. Cd versus Cu contents of marine fraction in sedimentary 

rocks of the Monterey Formation. Labeled curves represent 

averages. Data sources: circles, this study; squares, Leventhal 

(1989); dots, C.M. Isaacs (unpub. data, 1993).

from the ratio in plankton of 10 (fig. 14H). The Zn:Cu ratios 

in plankton, silica, and the Monterey Formation actually 

suggest that silica supplied a major part of minor elements 

to the sediment. This same mechanism might also contribute 

to the low Cd contents, but a sampling bias also contributes 

to the lower than expected average Cd content. The Cd-Cu 

relation has two separate trends (fig. 9A). The samples with 

the lower Cd:Cu ratios (phosphatic samples) seem to be 

disproportionately represented. Additional analyses for the 

Santa Barbara-Ventura Basin (C.M. Isaacs, unpub. data, 

1993) and the analyses by Leventhal (1989) for the Santa 

Maria Basin (fig. 15) also show these two trends, but most 

samples plot along the siliceous-shale trend.

An Ni content in biogenic silica needed to explain the 

shift in the Ni:Cu ratio (fig. 14D) seems to be much higher 

than we might expect to observe. Thus, the strong enrichment of Ni in these rocks must remain enigmatic until its 

distribution in biogenic phases is more fully evaluated. Its 

behavior during early diagenesis (Shaw and others, 1990) 

seems only to add to the problem; it is apparently remobilized under O2-depleted pore-water conditions.

The slight shift of Cd:Cu, Mo:Cu, Se:Cu, U:Cu, and 

Zn:Cu ratios all away from their plankton values, toward 

seawater values (fig. 14), might also be explained by a very 

brief excursion of bottom-water redox conditions into the 

field of sulfate reduction, as mentioned above. Just as the 

OMZ on the Peru Shelf can become sulfate reducing for 

brief periods of time (Dugdale and others, 1977), so might 

have the bottom water of this Miocene sea. A simple calculation, similar to that made for Mo accumulation in early 

Quaternary sediment from the Sea of Japan (Piper and Isaacs, 

1995), limits sulfate-reducing conditions in the bottom water considered here to less than about 1 percent of the time. 

Thus, accumulating organic matter remains the dominant 

source of these elements.

The variation in bottom-water redox is expressed by the 

difference in V contents in the phosphatic unit and the shale 

units (fig. 14G). The higher values in the shale units require 

accumulation under more strongly reducing bottom-water 

conditions (table 9), an interpretation that seems to conflict 

with the sulfur-isotopic data (Zaback and Pratt, 1992).

Our stoichiometric approach clearly has many problems because it is a simplified representation of an extremely complex system. Froelich and others (1979,1988), Bender 

and others (1989), Jahnke (1990), and Ingall and Van 

Cappellen (1990) revealed the complex geochemistry of 

major nutrients during diagenesis, from oxygen respiration, 

through manganese reduction, denitrification, Fe(III) reduction, and sulfate reduction, to methanogenesis. The behavior 

of minor elements during early diagenesis is likely to be 

equally complex (Shaw and others, 1990). As future research better defines the geochemistry of minor elements 

in the modern marine environment, our interpretation of 

their distributions in sedimentary rocks will surely require 

adjustment.
CONCLUSIONS 35

PALEOCEANOGRAPHY

The late Miocene ocean is commonly considered as 

representative of an ocean that underwent a global anoxic 

event—that is, sulfate-reducing conditions much more widespread in bottom water of the ocean than they are today. 

Evidence generally cited for this representation is the seemingly vast areal extent of formations of this age with high 

organic-matter and minor-element contents, similar to those 

of the Monterey Formation, and on the interpretation that 

sedimentary rocks of this composition accumulated under 

seawater sulfate-reducing conditions. This environment has 

a very limited areal extent in the ocean today, and yet its 

accumulating sediment represents a major sink for several 

minor elements (Kolodny and Kaplan, 1970; Bertine and 

Turekian, 1973; Cutter, 1982; Jacobs and others, 1987; 

Emerson and Huested, 1991; Klinkhammer and Palmer, 

1991). Sediment within this environment may or may not 

have high minor-element contents, depending on the rate of 

accumulation of the detrital fraction (dilution), but it will 

have high minor-element-accumulation rates. The Monterey 

Formation has high minor-element contents but minorelement-accumulation rates that were typical of the modern 

shelf environment.

The effect of a global anoxic event on the distribution 

of minor elements in seawater would be drastic. In response 

to their accumulating over a much larger area of the sea 

floor, minor-element residence times and concentrations in 

the ocean would decrease sharply. The decrease would be 

felt worldwide and virtually instantaneously, owing to the 

very short residence times of most minor elements (Goldberg, 

1963b). Piper and Codispoti (1975) suggested that NO3 

might have the same fate, with the somewhat-unexpected 

consequence that if organic-matter enriched sedimentary 

rocks represent periods of global anoxia, they must also 

represent times of reduced global primary productivity.

The geochemistry of the Monterey Formation suggests 

another interpretation for its high contents of organic matter 

and minor elements. The high organic-matter content of this 

formation and, possibly, of rocks of correlative age results 

from low bulk-sediment-accumulation rates, that is, slight 

dilution by detrital phases and biogenic carbonates and silica, 

not from any significant change in primary productivity or 

in the geochemistry of the world's ocean. Locally, primary 

productivity during much of the time represented by the 

Monterey Formation was probably no higher than it is today 

in the California Current. Similarly, high minor-element 

contents reflect this moderate primary productivity and low 

accumulation rate of diluting sediment fractions. The accumulation rates of Cr and V, alone, required a somewhatexpanded distribution of denitrifying bottom water, from its 

current restricted distribution in the Santa Barbara Basin. 

This local expansion of O2-depleted bottom water, however, 

probably had no global significance. Interelement ratios of 

all minor elements in the Monterey Formation can be explained by accumulation from a seawater with minor-element contents similar to those in the North Pacific Ocean 

today; in fact, interelement ratios in the Monterey Formation require such an ocean.

CONCLUSIONS

Analysis of 9 major-element oxides and 33 minor elements in 22 samples of the Sisquoc and Monterey Formations and Rincon Shale were carried out in three laboratories 

by ICP, NAA, and XRF methods. The precision of most 

analyses, on the basis of agreement of the results between 

laboratories, was better than 5 percent, allowing us to identify contributions of the minor elements by terrigenous debris, marine-biogenic matter, and marine hydrogenous 

phases.

The interelement ratios between major-element oxides 

(A12O3 , K2O, TiO2) and minor elements (Co, Cs, Ga, Hf, Li, 

Sc, Th) closely approach those of NASC and (or) WSA 

standards. These ratios indicate that the detrital fraction was 

the sole source for these elements and that it itself had a 

terrigenous source. The strength of these relations allows us 

to determine the detrital contribution to the total inventory 

of other minor elements (Cd, Cr, Cu, Mo, Ni, Se, U, Zn, 

REE's) and Fe2O3 from the Al2O3 :minor-elemental ratios 

in the standards and the A12O3 content of each individual 

sample. The residual content of this group of minor elements and Fe2O3 represents, then, the marine contribution.

The interelement ratios between Cd, Cu, Mo, Se, Zn, 

and Fe in this marine fraction of the rocks approximate the 

corresponding interelement ratios in modern plankton, suggesting that these minor elements had a predominantly biogenic source. During Monterey time, the rate of accumulation 

of organic matter on the sea floor of the Miocene Santa 

Barbara-Ventura and Santa Maria Basins necessary to provide these elements to the sediment was approximately equal 

to that on the present-day California Continental Shelf, an 

area of moderately intense coastal upwelling and primary 

productivity in the photic zone of the water column.

The enrichments of Cr, V, and REE's required accumulation directly from seawater, a hydrogenous input. On the 

basis of their chemical properties and distributions in O2- 

depleted environments of the ocean today, their accumulation from seawater would have been enhanced by conditions 

of denitrification in the bottom water. Their rates of accumulation in Monterey sediment limited the residence time 

of bottom water in the basin to a maximum of approximately 

5 yr. This residence time is the same as that necessary to 

establish denitrification in the bottom water by way of the 

oxidation of settling organic matter.

Sulfate reduction was not established in the bottom 

water through bacterial respiration, an interpretation based 

on the preservation of a seawater-derived enrichment of 

REE's in the Monterey Formation, the absence of a strong
36 GEOCHEMISTRY OF MINOR ELEMENTS IN THE MONTEREY FORMATION, CALIFORNIA

marine input of U, and the absence of enrichments of Cu, 

Cd, Se, Zn, and, particularly, Mo above a biogenic input. 

Otherwise, Cu, Cd, Se, Zn, and Mo would have accumulated 

as inorganic sulfides, in addition to accumulating in an 

organic fraction, and REE's would not have accumulated 

from seawater at all but would have had solely a terrigenous 

source. A hydrogenous input of Mo, which is 5 to 50 times 

more abundant in seawater than V and Cr and 2,000 more 

abundant than REE's (La), would have been easily detected. 

Sulfate reduction was restricted to the sediment pore water; 

it likely closely approached the benthic boundary layer but 

did not extend into the overlying water column.

In the ocean today, no single environment represents a 

perfect analog of the Monterey Formation. The chemical 

and biologic processes and bathymetry that controlled the 

overall composition of these rocks do occur, but only within 

several shelf-slope environments. Also, the Monterey Formation was deposited over several million years, during 

which time the rocks recorded significant local oceanographic changes. The minor-element content of the Monterey 

Formation, however, requires that the chemistry of the open 

ocean during late Miocene time was identical to that of 

today.

REFERENCES CITED

Altschuler, Z.S., Herman, Sol, and Cuttitta, Frank, 1967, Rare 

earths in phosphorites—geochemistry and potential recovery, in Geological Survey research, 1967: U.S. Geological 

Survey Professional Paper 575-B, p. B1-B9.

Anbar, A.D., Greaser, R.A., Papanastassiou, D.A., and Wasserburg, 

G.J., 1992, Rhenium in seawater—confirmation of a generally conservative behavior: Geochemica et Cosmochemica 

Acta, v. 56, no. 11, p. 4099-4103.

Anderson, J.J., and Devol, A.H., 1973, Deep water renewal in 

Saanich Inlet, an intermittently anoxic basin: Estuarine and 

Coastal Marine Science, v. 1, no. 1, p. 1-10.

Anderson, R.F., Fleisher, M.Q., and LeHuray, A.P., 1989a, Concentration, oxidation state, and particle flux of uranium in the 

Black Sea: Geochimica et Cosmochimica Acta, v. 53, no. 9, 

p. 2215-2224.

Anderson, R.F., LeHuray, A.P., Fleisher, M.Q., and Murray, J.W., 

1989b, Uranium deposition in Saanich Inlet, Vancouver, Island: Geochimica et Cosmochimica Acta, v. 53, no. 9, p. 

2205-2213.

Arends, R.G., and Blake, G.H., 1986, Biostratigraphy and paleoecology of the Naples Bluff coastal section based on diatoms 

and benthic foraminifera, in Casey, R.E., and Barren, J.A., 

eds., Siliceous microfossil and microplankton of the Monterey 

Formation and modern analogs: Los Angeles, Society of 

Economic Paleontologists and Mineralogists, Pacific Section 

Field Trip Guidebook 45, p. 121-135.

Baedecker, P.A., ed., 1987, Methods for geochemical analysis: 

U.S. Geological Survey Bulletin 1770, 145 p.

Baines, S.B., Pace, M.L., and Karl, D.M., 1994, Why does the 

relationship between sinking flux and planktonic primary

productivity differ between lakes and oceans?: Limnology & 

Oceanography, no. 2, v. 39, p. 213-226.

Balistrieri, L.S., Brewer, P.G., and Murray, J.W., 1981, Scavenging residence times of trace metals and surface chemistry of 

sinking particles in the deep ocean: Deep-Sea Research, v. 

28, no. 2, p. 101-121.

Balistrieri, L.S., and Murray, J.W., 1984, Marine scavenging; 

trace metal adsorption by interfacial sediment from MANOP 

Site H: Geochimica et Cosmochimica Acta, v. 48, no. 5, p. 

921-929.

Barren, J.A., 1986, Updated diatom biostratigraphy for the 

Monterey Formation of California, in Casey, R.E., and Barren, 

J.A., eds., Siliceous microfossil and microplankton of the 

Monterey Formation and modern analogs: Los Angeles, Society of Economic Paleontologists and Mineralogists, Pacific 

Section Field Trip Guidebook 45, p. 105-119.

Baturin, G.N., Murkulova, K.I., and Chalov, P.I., 1972, Radiometric evidence for recent formation of phosphatic nodules in 

marine shelf sediments: Marine Geology, v. 13, no. 3, p. 

M37-M41.

Belzile, Nelson, Lecomte, Pierre, andTessier, Andr6,1989, Testing readsorption of trace elements during partial chemical 

extractions of bottom sediments: Environmental Science & 

Technology, v. 23, no. 8, p. 1015-1020.

Bender, Michael, Jahnke, Richard, Weiss, Ray, Martin, William, 

Heggie, D.T., Orchardo, Joseph, and Sowers, Todd, 1989, 

Organic carbon oxidation and benthic nitrogen and silica 

dynamics in San Clemente Basin, a continental borderland 

site: Geochimica et Cosmochimica Acta, v. 53, no. 3, p. 685- 

697.

Berger, W. H., Fischer, K., Lai, C., and Wu, G., 1988, Ocean 

carbon flux: global maps of primary production and export 

production, in Agegian, C.R., ed., Biogeochemical cycling 

and fluxes between the deep euphotic zone and other oceanic 

realms: U.S. National Oceanic and Atmospheric Administration, Under Sea Research Program Report 88-1, p. 131-176.

Bernal, P. A., and McGowan, J.A., 1981, Advection and upwelling 

in the California Current, in Richards, F.A., ed., Coastal 

upwelling, v. 1 of Coastal and estuarine science: Washington, D.C., American Geophysical Union, p. 381-399.

Berner, R.A., 1980, Early diagenesis: Princeton, N.J., Princeton 

University Press, 241 p.

Bertine, K.K., and Turekian, K.K., 1973, Mo in marine deposits: 

Geochimica et Cosmochimica Acta, v. 37, no. 6, p. 1415- 

1434.

Blueford, J.R., and Isaacs, C.M., 1989, Field trip guide to the 

Miocene Monterey Formation, Salinas and Santa Barbara 

area, California: International Geological Congress, 28th, 

Washington, D.C., 1989, no. T109, 50 p.

Bostrom, Kurt, Peterson, M.N.A., Joensuu, Oiva, and Fisher, D.E., 

1969, Aluminum-poor ferromanganoan sediments on active 

oceanic ridges: Journal of Geophysical Research, v. 74, no. 

12, p. 3261-3270.

Boust, Dominique, Carpenter, M.S.N., and Joron, J.L., 1988, Investigation of authigenic and diagenetic processes by chemical leaching of pelagic sediments from Cape Verde abyssal 

plain: Chemical Geology, v. 68, no. 1-2, p. 69-87.

Bowser, C.J., Mills, B.A., and Callender, Edward, 1979, Extractive chemistry of equatorial Pacific pelagic sediments and 

relationship to nodule forming processes, in Bischoff, J.L.
REFERENCES CITED 37

and Piper, D.Z., eds., Marine geology and oceanography of 

the Pacific manganese nodule province: New York, Plenum, 

p. 587-619.

Boyle, E.A., Sclater, F.R., and Edmond, J.M., 1976, On the marine 

geochemistry of cadmium: Nature, v. 263, no. 5572, p. 42-44.

———1977, The distribution of dissolved copper in the Pacific: 

Earth and Planetary Science Letters, v. 37, no. 1, p. 38-54.

Bramlette, M.N., 1946, The Monterey formation of California and 

the origin of its siliceous rocks: U.S. Geological Survey 

Professional Paper 212, 57 p.

Breit, G.N., and Wanty, R.B., 1991, Vanadium accumulation in 

carbonaceous rocks; a review of geochemical controls during 

deposition and diagenesis: Chemical Geology, v. 91, no. 2, p. 

83-97.

Brewer, P.G., and Spencer, D.W., 1974, Distribution of some trace 

elements in Black Sea and their flux between dissolved and 

paniculate phases, in Ross, D.A., and Degens, E.T., eds., The 

Black Sea—geology, chemistry, and biology: American Association of Petroleum Geologists Memoir 20, p. 137-143.

Broecker, W.S., and Peng, T.-H., 1982, Tracers in the sea: Palisades, N.Y., Eldigio Press, 690 p.

Bruland, K.W., 1983, Trace elements in seawater, in Riley, J.P., 

and Skirrow, Geoffrey, eds., Chemical oceanography: London, Academic Press, v. 8, p. 157-220.

Bruland, K.W., Bertine, K.K., Koide, Minoru, and Goldberg, E.D., 

1974, History of metal pollution in Southern California coastal 

zone: Environmental Science & Technology, v. 8, no. 5, p. 

425-432.

Brumsack, H.J., 1983, A note on black shales and recent sediments 

from oxygen deficient environments, paleoceanographic implications, in Suess, Erwin, and Theide, Jorn, eds., Coastal 

upwelling, its sediment records: New York, Plenum, p. 471- 

483.

———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 paleoceanography: Geological Society of London Special Publication 

21, p. 447-462.

Brumsack, H.J., and Gieskes, J.M., 1983, Interstitial water tracemetal chemistry of laminated sediments from the Gulf of 

California, Mexico: Marine Chemistry, v. 14, no. 1, p. 89-106.

Burnett, W.C., 1977, Geochemistry and origin of phosphorite 

deposits from off Peru and Chile: Geological Society of 

America Bulletin, v. 88, no. 6, p. 813-823.

Burnett, W.C., Baker, K.B., Chin, P.A., McCabe, William, and 

Ditchburn, Robert, 1988, Uranium-series and AMS 14C studies of modern phosphate pellets from Peru shelf muds: Marine Geology, v. 80, no. 3^4, p. 215-230.

Burnett, W.C., and Froelich, P.N., 1988, The origin of marine 

phosphorite; the results of the R/V Robert D. Conrad Cruise 

23-06 to the Peru shelf: Marine Geology, v. 80, no. 3-4, p. 

181-343.

Callender, Edward, and Bowser, C.J., 1980, Manganese and copper geochemistry of interstitial fluids from manganese nodule-rich pelagic sediments of the northeastern equatorial 

Pacific Ocean: American Journal of Science, v. 280, no. 10, 

p. 1063-1096.

Calvert, S.E., 1976, The mineralogy and geochemistry of nearshore sediments, in Riley, J.P., and Chester, Roy, eds., Chemical oceanography: London, Academic Press, v. 6, p. 187- 

280. 

-1990, Geochemistry and origin of the Holocene sapropel in

the Black Sea, in Ittekkot, Venugopalan, Kempe, Stephan, 

Michaelis, Walter, and Spitzy, Alejandro, eds., Facets of 

modern biogeochemistry: Berlin, Springer-Verlag, p. 326-352. 

Calvert, S.E., and Price, N.B., 1971, Upwelling and nutrient regeneration in the Benguela Current, October, 1968: Deep-Sea 

Research, v. 18, no. 5, p. 505-523.

———1983, Geochemistry of Namibian shelf sediments, in Suess, 

Erwin, and Thiede, J6rn, eds., Coastal upwelling, its sediment records: New York, Plenum, p. 337-375.

Chavez, P.P., and Barber, R.T., 1987, An estimate of new production in the equatorial Pacific: Deep-Sea Research, v. 34, no. 

7, p. 1229-1244.

Chester, Roy, and Hughes, M.J., 1967, A chemical technique for 

the separation of ferro-manganese nodules, carbonate minerals and absorbed trace elements from pelagic sediments: 

Chemical Geology, v. 2, no. 3, p. 249-262.

Church, T.M., 1979, Marine barite, in Burns, R.G., ed., Marine 

minerals: Washington, D.C., Mineralogical Society of 

America, p. 175-209.

Claypool, G.E., and Threlkeld, C.N., 1983, Anoxic diagenesis and 

methane generation in sediments of the Blake outer ridge, 

Deep-Sea Drilling Project Site 533, Leg 76: Deep-Sea Drilling Project Initial Reports, v. 76, p. 391-402.

Clegg, S.L., and Sarmiento, J.L., 1989, The hydrolytic scavenging 

of metal ions by marine paniculate matter: Progress in Oceanography, v. 23, no. 1, p. 1-21,

Codispoti, L.A., 1980, Temporal nutrient variability in three different upwelling regimes, in Richards, F.A., ed., Coastal 

upwelling, v. 1 of Coastal and estuarine sciences: Washington, D.C., American Geophysical Union, p. 209-220.

———1989, Phosphorus vs. nitrogen limitation of new and export production, in Berger, W.H., Smetacek, V.S., and Wefer, 

Gerold, eds., Productivity of the oceans; present and past: 

Chichester, U.K., John Wiley and Sons, p. 377-394.

Codispoti, L.A., Friederich, G.E., Murray, J.W., and Sakamoto, 

C.M., 1991, Chemical variability in the Black Sea; implications of continuous vertical profiles that penetrated the oxic/ 

anoxic interface: Deep-Sea Research, v. 38, supp. 2, p. S691- 

S710.

Collier, R.W., 1984, Paniculate and dissolved vanadium in the 

North Pacific Ocean: Nature, v. 309, no. 5967, p. 441-444.

———1985, Molybdenum in the Northeast Pacific Ocean: Limnology and Oceanography, v. 30, no. 6, p. 1351-1354.

Collier, R.W., and Edmond, J.M., 1984, The trace element chemistry of marine biogenic paniculate matter: Progress in Oceanography, v. 13, no. 2, p. 113-119.

Cook, P.J., and Shergold, J.H., 1986, Proterozoic and Cambrian 

phosphorites—nature and origin, in Cook, P.J., and Shergold, 

J.H., eds., Proterozoic and Cambrian phosphorites, v. 1 of 

Phosphate deposits of the world: London, Cambridge University Press, p. 369-386.

Cutter, G.A., 1982, Selenium in reducing waters: Science, v. 217, 

no. 4562, p. 829-831.

Cutter, G.A., and Bruland, K.W., 1984, The marine biogeochemistry of selenium; a re-evaluation: Limnology and Oceanography, v. 29, no. 6, p. 1179-1192.

Dean, W.E., and Arthur, M.A., 1992, Sediments in the Black Sea
38 GEOCHEMISTRY OF MINOR ELEMENTS IN THE MONTEREY FORMATION, CALIFORNIA

and Peru margin as analogues for metalliferous black shales; 

where's the beef: Geochemical Society V.M. Goldschmidt 

Conference, 1992, Programs and Abstracts, p. A26-A27.

de Baar, HJf.W., Bacon, M.P., Brewer, P.O., and Bruland, K.W., 

1985, Rare earth elements in the Pacific and Atlantic Oceans: 

Geochimica et Cosmochimica Acta, v. 49, no. 9, p. 1943-1959.

de Baar, H.J.W., German, C.R., Elderfield, Henry, and van Gaans, 

Pauline, 1988, Rare earth element distributions in anoxic 

waters of the Cariaco Trench: Geochimica et Cosmochimica 

Acta, v. 52, no. 5, p. 1203-1219.

Demaison, G.J., and Moore, G.T., 1980, Anoxic environments and 

oil source bed genesis: Organic Geochemistry, v. 2, no. 1, p. 

9-31.

DePaolo, D.J., and Finger, K.L., 1991, High-resolution strontiumisotope stratigraphy and biostratigraphy of the Miocene 

Monterey Formation, central California: Geological Society 

of America Bulletin, v. 103, no. 1, p. 112-124.

Donnelley, T.H., Shergold, JNH., and Southgate, P.N., 1988, Anomalous geochemical signals from phosphatic Middle Cambrian 

rocks in the southern Georgina Basin, Australia: Sedimentology, v. 35, no. 4, p. 549-570.

Douglas, G.S., Mills, G.L., and Quinn, J.G., 1986, Organic copper 

and chromium complexes in the interstitial waters of 

Narragansett Bay sediments: Marine Chemistry, v. 19, no. 2, 

p. 161-174.

Dugdale, R.C., and Goering, J.J., 1970, Nutrient limitation and the 

path of nitrogen in Peru Current production: Anton Bruun 

Reports, v. 5, p. 3-8.

Dugdale, R.C., J.J. Goering, R.T. Barber, R.L. Smith, and T.T. 

Packard, 1977, Denitrification and hydrogen sulfide in the 

Peru upwelling region during 1976: Deep-Sea Research, v. 

24, no. 6, p. 601-608.

Dunbar, R.B., and Berger, W.H., 1981, Fecal pellet flux to modern 

bottom sediment of Santa Barbara Basin (California) based 

on sediment trapping: Geological Society of America Bulletin, pt. 1, v. 92, no. 4, p. 212-218.

Dymond, Jack, 1981, Geochemistry of Nazca Plate surface sediment; an evaluation of hydrothermal, biogenic, detrital, and 

hydrogenous sources, in Kulm, L.D., Dymond, Jack, Dasch, 

E.J., and Hussong, D.M., eds., Nazca Plate; crustal formation 

and Andean convergence: Geological Society of America 

Memoir 154, p. 133-173.

Eisler, Ronald, 1981, Trace metal concentrations in marine organisms: New York, Pergamon, 687 p.

Elderfield, Henry, 1970, Chromium speciation in sea water: Earth 

and Planetary Science Letters, v. 9, p. 10-16.

Elderfield, Henry, Hawkesworth, C.J., Greaves, M.J., and Calvert, 

S.E., 1981, Rare earth element geochemistry of oceanic 

ferromanganese nodules and associated sediments: Geochimica et Cosmochimica Acta, v. 45, no. 4, p. 513-528.

Elderfield, Henry, and Sholkovitz, E.R., 1987, Rare earth elements in pore waters of reducing nearshore sediments: Earth 

and Planetary Science Letters, v. 82, no. 3-4, p. 280-288.

Emerson, S.R., Cranston, R.E., and Liss, P.S., 1979, Redox species in a reducing fjord—equilibrium and kinetic observations: Deep-Sea Research, v. 26, no. 8, p. 859-878.

Emerson, S.R., and Huested, S.S., 1991, Ocean anoxia and concentrations of molybdenum and vanadium in seawater: Marine Chemistry, v. 34, no. 3-4, p. 177-196.

Fischer, Kathleen, Dymond, Jack, Lyle, Mitchell, Soutar, Andrew,

and Rau, Susan, 1986, The benthic cycle of copper; evidence 

from sediment trap experiments in the eastern tropical North 

Pacific Ocean: Geochimica et Cosmochimica Acta, v. 50, no. 

7, p. 1535-1543.

Fowler, S.W., 1977, Trace elements in zooplankton paniculate 

products: Nature, v. 269, no. 5623, p. 51-53.

Francois, Roger, 1988, A study on the regulation of the concentrations of some trace metals (Rb, Sr, Zn, Pb, Cu, V, Cr, Ni, Mn 

and Mo) in Saanich Inlet sediments, British Columbia, Canada: 

Marine Geology, v. 83, no. 1^, p. 285-308.

Froelich, P.N., Arthur, M.A., Burnett, W.C., Deakin, M., Hensley, 

V., Jahnke, R.A., Kaul, L., Kirn, K.H., Roe, K., Soutar, 

Andrew, and Vathakanon, C, 1988, Early diagenesis of organic matter Peru continental margin sediments, phosphorite 

precipitation: Marine Geology, v. 80, no. 3-4, p. 309-343.

Froelich, P.N., Klinkhammer, G.P., Bender, M.L., Luedtke, N.A., 

Heath, G.R., Cullen, Doug, and Dauphin, Paul, Hammond, 

Doug, Hartman, Blayne, and Maynard, Val, 1979, Early oxidation of organic matter in pelagic sediments of the eastern 

equatorial Atlantic; suboxic diagenesis: Geochimica et 

Cosmochimica Acta, v. 43, no. 7, p. 1075-1090.

Garrels, R.M., and Christ, C.L., 1965, Solution, minerals, and 

equilibia: New York, Harper and Row, 450 p.

German, C.R., Holliday, B.P., and Elderfield, Henry, 1991, Redox 

cycling of rare earth elements in the suboxic zone of the 

Black Sea: Geochimica et Cosmochimica Acta, v. 55, no. 12, 

p. 3553-3558.

———1993, Reply to the comment by E.R. Sholkovitz on "Redox 

cycling of rare earth elements in the suboxic zone of the 

Black Sea": Geochimica et Cosmochimica Acta, v. 56, no. 

12, p. 4309-4313.

Goldberg, E.D., 1954, Chemical scavengers of the sea: Journal of 

Geology, v. 62, no. 3, p. 249-265.

———1963a, Mineralogy and chemistry of marine sedimentation, in Shepard, P.P., Submarine geology (2d ed.): New 

York, Harper and Row, p. 436-466.

———1963b, The oceans as a chemical system, in Hill, M.N., ed., 

The composition of seawater; comparative and descriptive 

oceanography, v. 2 of The sea; ideas and observations on 

progress in the study of the sea: New York, Wiley-Interscience, 

p. 3-25.

Goldberg, E.D., Koide, Minoru, Schmitt, R.A., and Smith, R.M., 

1963, Rare earth distributions in the marine environment: 

Journal of Geophysical Research, v. 68, no. 14, p. 4209-4217.

Gorsline, D.S., and Teng, L.S.-Y., 1989, The California Borderland, in Winterer, E.L., Hussong, D.M., and Decker, R.W., 

eds., The Eastern Pacific Ocean and Hawaii, v. N of The 

geology of North America: Boulder, Colo., Geological Society of America, p. 471-487.

Govean, P.M., and Garrison, R.E., 1981, Significance of laminated and massive diatomites in the upper part of the Monterey 

Formation, California, in Garrison, R.E., and Douglas, R.G., 

eds., The Monterey Formation and related siliceous rocks of 

California: Los Angeles, Society of Economic Paleontologists and Mineralogists, Pacific Section, p. 181-198.

Gromet, L.P., Dymet, R.F., Haskin, L.A., and Korotev, R.L., 

1984, The "North American shale composite"; its composition, major and trace element characteristics: Geochimica et 

Cosmochimica Acta, v. 48, no. 12, p. 2469-2482.

Guichard, Francois, Church, T.M., Treuil, Michel, and Jafrezic,
REFERENCES CITED 39

Henri, 1979, Rare earth elements in marine barites; distribution and effects on aqueous partitioning: Geochimica et 

Cosmochimica Acta, v. 43, no. 7, p. 983-998.

Hart, T.J., and Currie, R.T., 1960, The Benguela Current: Discovery Reports, v. 31, p. 123-298.

Hashimoto, L.K., Kaplan, W.A., Wofsy, S.C., and McElroy, M.B., 

1983, Transformation of fixed nitrogen and N2O in the Cariaco 

Trench: Deep-Sea Research, v. 30, no. 6, p. 575-590.

Heggie, D.T., Kahn, D., and Fischer, K.M., 1986, Trace metals in 

metalliferous sediments, MANOP Site M; interfacial pore 

water profiles: Earth and Planetary Science Letters, v. 80, no. 

1-2, p. 106-116.

H0gdahl, Ove, 1967, Distribution of the rare earth elements in 

seawater: North American Treaty Organization Research Grant 

203, Progress Report, v. 4, p. 1-43.

Hopson, C.A., and Frano, C.J., 1977, Igneous history of the Point 

Sal ophiolite, southern California, in Coleman, R.G., and 

Irwin, W.P., eds., North American ophiolites: Oregon Department of Geology and Mineral Industries Bulletin 95, p. 

161-183.

Ingall, E.D., and Van Cappellen, Philippe, 1990, Relation between 

sedimentation rate and burial of organic phosphorus and organic carbon in marine sediments: Geochimica et Cosmochimica Acta, v. 54, no. 2, p. 373-386.

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.

———1985, Abundance versus rates of accumulation in finegrained strata of the Miocene Santa Barbara Basin, California: Geo-Marine Letters, v. 5, no. 1, p. 25-30.

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 OCSCAL 78-164 No. 1 off Southern California, in Isaacs, C.M., 

and Garrison, R.E., eds., Petroleum generation and occurrence in the Miocene Monterey Formation, California: Los 

Angeles, Society of Economic Paleontologists and Mineralogists, Pacific Section, p. 99-110.

Isaacs, C.M., Pollastro, R.M., Arends, R.G., Barron, J.A., Cotton, 

M.L., Filewicz, M.V., Flower, B.P., and Piper, D.Z., 1992, 

Preliminary data on rock samples (KG-1 to KG-24) in the 

Cooperative Monterey Organic Geochemistry Study; Santa 

Maria and Santa Barbara-Ventura basins, California: U.S. 

Geological Survey Open-File Report 92-539-C, 29 p.

Isaacs, C.M., Tomson, J.H., Lewan, M.D., Arends, R.G., Cotton, 

M.L., and Filewicz, M.V., 1992, Preliminary correlation and 

age of rock samples (KG-1 to KG-24) in the Cooperative 

Monterey Organic Geochemistry Study, Santa Maria and 

Santa Barbara-Ventura basins, California: U.S. Geological 

Survey Open-File Report 92-539-D, 12 p.

Jacobs, Lucinda, Emerson, S.R., and Skei, Jens, 1985, Partitioning 

and transport of metals across the O2/H2S interface in a 

permanently anoxic basin; Framvaren Fjord, Norway: 

Geochimica et Cosmochimica Acta, v. 49, no. 6, p. 1433- 

1444.

Jacobs, Lucinda, Emerson, S.R., and Huested, S.S., 1987, Trace 

metal chemistry in the Cariaco Trench: Deep-Sea Research, 

v. 34, no. 5-6A,p. 965-981.

Jahnke, R.A., 1990, Early diagenesis and recycling of biogenic

debris at the sea floor, Santa Monica Basin, California: Journal of Marine Research, v. 48, no. 2, p. 413-436.

Jenkyns, H.C., 1980, Cretaceous anoxic events; from continents to 

oceans: Geological Society of London Journal, v. 137, pt. 2, 

p. 171-188.

Klinkhammer, G.P., and Bender, M.L., 1980, The distribution of 

manganese in the Pacific Ocean: Earth and Planetary Science 

Letters, v. 46, no. 3, p. 361-384.

Klinkhammer, G.P., Heggie, D.T., and Graham, D.W., 1982, Metal 

diagenesis in oxic marine sediments: Earth and Planetary 

Science Letters, v. 61, no. 2, p. 211-219.

Klinkhammer, G.P., and Palmer, M.R., 1991, Uranium in the 

oceans; where it goes and why: Geochimica et Cosmochimica 

Acta, v. 55, no. 7, p. 1799-1806.

Koide, Minoru, Hodge, V.F., Yang, J.S., Stallard, Martha, Goldberg, 

E.D., Calhoun, J., and Bertine, K.K., 1986, Some comparative marine chemistries of rhenium, gold, silver and molybdenum: Applied Chemistry, v. 1, no. 6, p. 705-714.

Kolodny, Yehoshua, and Kaplan, I.R., 1970, Carbon and oxygen 

isotopes in apatite CO2 and co-existing calcite from sedimentary phosphorite: Journal of Sedimentary Petrology, v. 40, 

no. 3, p. 954-959.

Krauskopf, K.B., 1956, Factors controlling the concentrations of 

thirteen rare metals in sea water: Geochimica et Cosmochimica 

Acta, v. 9, no. l,p. 1-32.

Kremling, Klaus, 1983, The behavior of Zn, Cd, Cu, Ni, Co, Fe, 

and Mn in anoxic Baltic waters: Marine Chemistry, v. 13, no. 

1^, p. 87-108.

Landing, W.M., and Bruland, K.M., 1987, The contrasting biogeochemistry of iron and manganese in the Pacific Ocean: 

Geochimica et Cosmochimica Acta, v. 51, no. 1, p. 29-44.

Landing, W.M., and Lewis, B.L., 1991, Thermodynamic modelling of trace metal speciation in the Black Sea, in Izdar, Erol, 

and Murray, J.W., eds., Black Sea oceanography: Dordrecht, 

Kluwer, p. 125-160.

Langmuir, Donald, 1978, Uranium solution-mineral equilibria at 

low temperatures with applications to sedimentary ore deposits: Geochimica et Cosmochimica Acta, v. 42, no. 6, p. 547- 

569.

Latimer, W.M., 1953, Oxidation potentials: New York, PrenticeHall, 392 p.

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.

Leinen, Margaret, and Pisias, Nicolas, 1984, An objective technique for determining endmember composition and for partitioning sediments according to their sources: Geochimica et 

Cosmochimica Acta, v. 48, no. 1, p. 47-62.

Leventhal, J.S., 1989, Geochemistry of minor and trace elements 

of 22 core samples from the Monterey Formation and related 

rocks in the Santa Maria Basin, California: U.S. Geological 

Survey Bulletin 1581-B, p. B1-B11.

Lewan, M.D., 1984, Factors controlling the proportionality of 

vanadium to nickel in crude oils: Geochimica et Cosmochimica 

Acta, v. 48, no. 11, p. 2231-2238.

Li, Y.-H., 1981, Ultimate removal mechanisms of elements from 

the oceans: Geochimica et Cosmochimica Acta, v. 45, no. 10, 

p. 1659-1664.

Lyle, Mitchell, Heath, G.R., and Robbins, J.M., 1984, Transport
40 GEOCHEMISTRY OF MINOR ELEMENTS IN THE MONTEREY FORMATION, CALIFORNIA

and release of transition elements during early diagenesis; 

sequential leaching of sediments from MANOP Sites M and 

H. Part I. pH 5 acetic acid leach: Geochimica et Cosmochimica 

Acta, v. 48, no. 9, p. 1705-1715.

Manheim, F.T., and Landergren, Sture, 1978, Molybdenum, in 

Wedepohl, K.H., ed., Handbook of Geochemistry: Berlin, 

Springer-Verlag, v. II/4, p. K1-K14.

Martin, J.H., and Knauer, G.A., 1973, The elemental composition 

of plankton: Geochimica et Cosmochimica Acta, v. 37, no. 7, 

p. 1639-1653.

McArthur, J.M., and Walsh, J.N., 1984, Rare-earth geochemistry 

in phosphorites: Chemical Geology, v. 47, no. 2, p. 191-220.

Measures, C.I., McDuff, R.E., and Edmond, J.M., 1980, Selenium 

redox chemistry at GEOSECS I re-occupation: Earth and 

Planetary Science Letters, v. 49, no. 1, p. 102-108.

Measures, C.I., Grant, B.C., Mangum, B.J., and Edmond, J.M., 

1983, The relation of the distribution of selenium IV and VI 

in three oceans to physical and biological processes, in Wong, 

C.S., Boyle, Edward, Bruland, K.W., Burton, J.D., and 

Goldberg, E.D., eds., Trace metals in seawater: New York, 

Plenum, p. 73-83.

Medrano, M.A., and Piper, D.Z., 1992, 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, p. A1-A23.

Mero, John, 1965, The marine mineral resources of the sea: 

Amsterdam, Elsevier, 312 p.

Moldowan, J.M., Sundararaman, Padmanabhan, and Schoell, Martin, 1986, Sensitivity of biomarker properties to depositional 

environments and/or source input in the lower Toarcian of 

SW Germany: Organic Geochemistry, v. 10, no. 4-6, p. 915- 

926.

Mossmann, J.-R., Aplin, A.C., Curtis, C.D., and Coleman, M.L., 

1991, Geochemistry of inorganic and organic sulfur in organic-rich sediments from the Peru Margin: Geochimica et 

Cosmochimica Acta, v. 55, no. 12, p. 3581-3595.

Murray, J.W., Spell, Berry, and Paul, Barbara, 1983, The contrasting geochemistry of manganese and chromium in the eastern 

tropical Pacific Ocean, in Wong, C.S., Boyle, Edward, 

Bruland, K.W., Burton, J.D., and Goldberg, E.D., eds., Trace 

metals in seawater: New York, Plenum, p. 643-669.

Murray, J.W., Top, Zafer, and Ozsoy, Emin, 1991, Hydrographic 

properties and ventilation of the Black Sea: Deep-Sea Research, v. 38, supp. 2A, p. S663-S689.

Nelson, D.M., Goering, J.J., and Boisseau, D.W., 1981, Consumption and regeneration of silicic acid in three coastal upwelling 

systems, in Richards, F.A., ed., Coastal upwelling, v. 1 of 

Coastal and estuarine science: Washington, D.C., American 

Geophysical Union, p. 242-256.

Nissenbaum, Arie, and Swaine, D.J., 1976, Organic matter-metal 

interactions in Recent sediments; the role of humic substances: Geochimica et Cosmochimica Acta, v. 40, no. 7, p. 

809-816.

Nordstrom, D.K., and Munoz, J.L., 1985, Geochemical thermodynamics: Menlo Park, N.J., Benjamin-Cummings, 477 p.

Odermatt, J.R., 1986, Transition element chemistry of organic 

matter in the Monterey Formation, Union Leroy 51-18 Well, 

Santa Maria Valley Field, Santa Barbara Co., California: Los

Angeles, California State University, M.S. thesis, 213 p.

Odermatt, J.R., and Curiale, J.A., 1991, Organically bound metals 

and biomarkers in the Monterey Formation of the Santa Maria 

Basin, California: Chemical Geology, v. 91, no. 2, p. 99- 

103.

Ostlund, H.G., 1974, Expedition "Odysseus 65"—radiocarbon age 

of Black Sea bottom water, in Degens, E.T., and Ross, D.A., 

eds., The Black Sea—geology, chemistry, and biology: American Association of Petroleum Geologists Memoir 20, p. 

127-132.

Palmer, M.A., 1985, Rare earth elements in foraminifera tests: 

Earth and Planetary Science Letters, v. 73, no. 2-4, p. 285- 

298.

Pedersen, T.F., and Calvert, S.E., 1990, Anoxia vs productivity; 

what controls the formation of organic-carbon-rich sediments 

and sedimentary rocks?: American Association of Petroleum 

Geologists Bulletin, v. 74, no. 4, p. 454-466.

Pedersen, T.F., Waters, R.D., and MacDonald, R.W., 1989, On the 

natural enrichment of cadmium and molybdenum in the sediments of Ucluelet Inlet, British Columbia: Science of the 

Total Environment, v. 79, no. 2, p. 125-139.

Piper, D.Z., 1974, Rare earth elements in the sedimentary cycle; a 

summary: Chemical Geology, v. 14, no. 4, p. 285-304.

————1988, The metal oxide fraction of pelagic sediment in the 

equatorial North Pacific Ocean; a source of metals in 

ferromanganese nodules: Geochimica et Cosmochimica Acta, 

v. 52, no. 8, p. 2127-2145, 

-1991, Geochemistry of a Tertiary phosphate deposit; Baja

California Sur, Mexico: Chemical Geology, v. 92, no. 4, p. 

283-316.

Piper, D.Z., Baedecker, P.A., Crock, J.G., Burnett, W.C., and 

Loebner, B.J., 1988, Rare earth elements in phosphatic-enriched sediment of the Peru shelf: Marine Geology, v. 80, no. 

3-4, p. 269-285.

Piper, D.Z., and Codispoti, L.A., 1975, Marine phosphorite deposits and the nitrogen cycle: Science, v. 188, no. 4183, p. 15-18.

Piper, D.Z., and Isaacs, C.M., 1995, Minor elements in Quaternary 

sediment from the Sea of Japan; a record of surface-water 

productivity and intermediate-water redox conditions: Geological Society of America Bulletin, v. 107, p. 54-67.

Piper, D.Z., and Wandless, G.A., 1992, Hydroxylamine-hydrochloride-acetic-acid-soluble and -insoluble fractions of pelagic sediment; readsorption revisited: Environmental Science 

& Technology, v. 26, no. 12, p. 2489-2493.

Piper, D.Z., and Medrano, M.D., 1994, Geochemistry of the 

Phosphoria Formation at Montpelier Canyon, Idaho; environment of deposition: U.S. Geological Survey Bulletin 2023-B, 

p. B1-B28.

Pisciotto, K.A., and Garrison, R.E., 1981, Lithofacies and depositional environments of the Monterey Formation, California, 

in Garrison, R.E. and Douglas, R.G., eds., The Monterey 

Formation and related siliceous rocks of California: Los Angeles, Society of Economic Paleontologists and Mineralogists, Pacific Section, p. 97-122.

Redfield, A.C., Ketchum, B.H., and Richards, F.A., 1963, The 

influence of organisms on the composition of seawater, in 

Hill, M.N., ed., The composition of seawater; comparative 

and descriptive oceanography, v. 2 of The sea; ideas and 

observations on progress in the study of the sea: New York, 

Wiley-Interscience, p. 26-77.
REFERENCES CITED 41

Reimers, C.E., and Suess, Erwin, 1983, Late Quaternary fluctuations in the cycling of organic matter off central Peru, in 

Suess, Erwin, and Theide, Jorn, eds., Coastal upwelling, its 

sediment records; part A, Responses of the sedimentary regime to present coastal upwelling: London, Plenum, p. 497- 

526.

Sadiq, Muhammad, 1988, Thermodynamic solubility relationships 

of inorganic vanadium in the marine environment: Marine 

Chemistry, v. 23, no. 1-2, p. 87-96.

Sarnthein, Michael, Winn, Kyaw, Duplessy, J.-C, and Fontugne, 

M.R., 1988, Global variations of surface ocean productivity 

in low and mid latitudes; influence on CO2 reservoirs on the 

deep ocean and atmosphere during the last 21,000 years: 

Paleoceanography, v. 3, no. 3, p. 361-399.

Schlanger, S.O., Arthur, M.A., Jenkyns, H.C., and Scholle, P.A., 

1987, The Cenomanian-Turonian ocean anoxic event, 1. 

Stratigraphy and distribution of organic carbon-rich beds and 

the marine d13C excursion, in Brooks, James, and Fleet, A.J., 

eds., Marine petroleum source rocks: Geological Society of 

London Special Publication 26, p. 371-399.

Schijf, Johan, de Baar, H.J.W., Wijbrans, J.R., and Landing, W.M., 

1991, Dissolved rare earth elements in the Black Sea: DeepSea Research, v. 38, supp. 2A, p. S805-S823.

Sclater, R.F., Boyle, Edward, and Edmond, J.M., 1976, On the 

marine geochemistry of nickel: Earth and Planetary Science 

Letters, v. 31, no. 7, p. 119-128.

Shaw, T.J., Gieskes, J.M., and Jahnke, R.A., 1990, Early diagenesis in differing depositional environments; the response of 

transition metals in pore water: Geochimica et Cosmochimica 

Acta, v. 54, no. 5, p. 1233-1246.

Sholkovitz, E.R., 1973, Interstitial water chemistry of Santa Barbara Basin sediments: Geochimica et Cosmochimica Acta, v. 

37, no. 9, p. 2043-2073.

———1990, Rare-earth elements in marine sediments and 

geochemical standards: Chemical Geology, v. 88, no. 3-4, p. 

333-347. 

-1993, Comment on "Redox cycling of rare earth elements

in the suboxic zone of the Black Sea" by C.R. German, B.P. 

Holliday, and H. Elderfield: Geochimica et Cosmochimica 

Acta, v. 56, no. 12, p. 4305-4307.

Sholkovitz, E.R., Landing, W.M., and Lewis, B.L., 1994, Ocean 

particle chemistry; the fraction of rare earth elements between suspended particles and seawater: Geochimica et 

Cosmochimica Acta, v. 58, n. 6, p. 1567-1579.

Sverdrup, H.U., Johnson, M.W., and Fleming, R.H., 1942, The 

oceans, their physics, chemistry, and general biology: New 

Jersey, Prentice-Hall, 1,087 p.

Swanson, V.E., 1961, Geology and geochemistry of uranium in 

marine black shales, a review: U.S. Geological Survey Professional Paper 356-C, p. 67-112.

Tessier, Andre\ Campbell, P.G.C., Auclair, J.C., and Bisson, Marc, 

1984, Relationships between the partitioning of trace metals 

in sediments and their accumulation in the tissues of the 

freshwater mollusc Elliptic complanata in a mining area: 

Canadian Journal of Fisheries and Aquatic Science, v. 41, no. 

10, p. 1463-1472.

Tessier, Andre\ and Campbell, P.G.C., 1991, Comment on "Pitfalls of sequential extractions" by P.M.V. Nirel and F.M.M. 

Morel, Wat. Res. 24, 1055-1056 (1990): Water Research, v. 

25, no. 1, p. 115-117.

van Andel, T.H., and Calvert, S.E., 1971, Evolution of a sediment 

wedge, Walvis shelf, southwest Africa: Journal of Geology, 

v. 79, no. 5, p. 585-602.

Von Bockel, Klaus, 1981, A note on short-term production and 

sedimentation in the upwelling region off Peru, in Richards, 

F.A., ed., Coastal upwelling, v. 1 of Coastal and estuarine 

sciences: Washington, D.C., American Geophysical Union, 

p. 291-297.

Wagman, D.D., Evans, W.H., Parker, V.B., Schumm, R.H., Halow, 

I., Bailey, S.M., Churney, K.L., and Nutall, R.L., 1982, The 

NBS tables of chemical thermodynamic properties: Journal 

of Physical Chemistry, Reference Data, supp. 2, 392 p.

Wanty, R.B., and Goldhaber, M.B., 1992, Thermodynamics and 

kinetics of reactions involving vanadium in natural systems; 

accumulation of vanadium in sedimentary rocks: Geochimica 

et Cosmochimica Acta, v. 56, no. 4, p. 1471-1483.

Waples, N.W., 1983, Reappraisal of anoxia and organic richness 

with emphasis of Cretaceous of North Atlantic: American 

Association of Petoleum Geologists Bulletin, v. 67, no. 6, p. 

963-978.

Wedepohl, K.H., ed., 1969-78, Handbook of geochemistry: Berlin, Springer-Verlag, 4 v.

Whitfield, Michael, and Turner, D.R., 1987, The role of particles 

in regulating the composition of seawater, in Stumm, Werner, 

ed., Aquatic surface chemistry: New York, John Wiley and 

Sons, p. 457-493.

Wright, Judith, Schrader, Hans, and Holser, W.T., 1987, Paleoredox 

variations in ancient oceans recorded by rare earth elements 

in fossil apatite: Geochimica et Cosmochimica Acta, v. 51, 

no. 3, p. 631-644.

Youngbluth, M.J., Bailey, T.G., Davoll, P.J., Jacoby, C.A., BladesEckelbarger, P.I., and Griswold, C.A., 1989, Fecal pellet 

production and diel migratory behavior by the euphausiid 

Meganyctiphanes norvegica effect benthic-pelagic coupling: 

Deep-Sea Research, v. 36, no. 10, p. 1491-1501.

Zaback, D.A., and Pratt, L.M., 1992, Isotopic composition and 

speciation of sulfur in the Miocene Monterey Formation; 

reevaluation of sulfur reactions during early diageneses in 

marine environments: Geochimica et Cosmochimica Acta, v. 

56, no. 2, p. 763-774.

GPO 683-048/20003
SELECTED SERIES OF U.S. GEOLOGICAL SURVEY PUBLICATIONS

Periodicals

Earthquakes & Volcanoes (issued bimonthly). 

Preliminary Determination of Epicenters (issued monthly).

Technical Books and Reports

Professional Papers are mainly comprehensive scientific reports 

of wide and lasting interest and importance to professional scientists 

and engineers. Included are reports on the results of resource studies 

and of topographic, hydrologic, and geologic investigations. They also 

include collections of related papers addressing different aspects of a 

single scientific topic.

Bulletins contain significant data and interpretations that are of lasting scientific interest but are generally more limited in scope or geographic coverage than Professional Papers. They include the results of 

resource studies and of geologic and topographic investigations, as well 

as collections of short papers related to a specific topic.

Water-Supply Papers are comprehensive reports that present significant interpretive results of hydrologic investigations of wide interest 

to professional geologists, hydrologists, and engineers. The series covers 

investigations in all phases of hydrology, including hydrogeology, availability of water, quality of water, and use of water.

Circulars present administrative information or important scientific information of wide popular interest in a format designed for distribution at no cost to the public. Information is usually of short-term 

interest.

Water-Resource Investigations Reports are papers of an 

interpretive nature made available to the public outside the formal 

USGS publications series. Copies are reproduced on request unlike 

formal USGS publications, and they are also available for public 

inspection at depositories indicated in USGS catalogs.

Open-File Reports include unpublished manuscript reports, maps, 

and other material that are made available for public consultation at 

depositories. They are a nonpermanent form of publication that may 

be cited in other publications as sources of information.

Maps

Geologic Quadrangle Maps are multicolor geologic maps on topographic bases in 7 Yz- or 15-minute quadrangle formats (scales mainly 

1:24,000 or 1:62,500) showing bedrock, surficial, or engineering geology. Maps generally include brief texts; some maps include structure 

and columnar sections only.

Geophysical Investigations Maps are on topographic or planimetric bases at various scales; they show results of surveys using 

geophysical techniques, such as gravity, magnetic, seismic, or radioactivity, which reflect subsurface structures that are of economic or geologic significance. Many maps include correlations with the geology.

Miscellaneous Investigations Series Maps are on planimetric or 

topographic bases of regular and irregular areas at various scales; they 

present a wide variety of format and subject matter. The series also 

includes 7 /4-minute quadrangle photogeologic maps on planimetric 

bases that show geology as interpreted from aerial photographs. Series 

also includes maps of Mars and the Moon.

Coal Investigations Maps are geologic maps on topographic or 

planimetric bases at various scales showing bedrock or surficial geology, stratigraphy, and structural relations in certain coal-resource 

areas.

Oil and Gas Investigations Charts show stratigraphic information for certain oil and gas fields and other areas having petroleum 

potential.

Miscellaneous Field Studies Maps are multicolor or black-andwhite maps on topographic or planimetric bases on quadrangle or irregular areas at various scales. Pre-1971 maps show bedrock geology 

in relation to specific mining or mineral-deposit problems; post-1971 

maps are primarily black-and-white maps on various subjects, such as 

environmental studies or wilderness mineral investigations.

Hydrologic Investigations Atlases are multicolor or black-andwhite maps on topographic or planimetric bases presenting a wide range 

of geohydrologic data of both regular and irregular areas; principal 

scale is 1:24,000, and regional studies are at 1:250,000 scale or smaller.

Catalogs

Permanent catalogs, as well as some others, giving comprehensive 

listings of U.S. Geological Survey publications are available under the 

conditions indicated below from the U.S. Geological Survey, Books 

and Open-File Reports Sales, Federal Center, Box 25286, Denver, CO 

80225. (See latest Price and Availability List.)

"Publications of the Geological Survey, 1879-1961" may be purchased by mail and over the counter in paperback book form and as a 

set of microfiche.

"Publications of the Geological Survey, 1962-1970" may be purchased by mail and over the counter in paperback book form and as a 

set of microfiche.

"Publications of the Geological Survey, 1971-1981" may be purchased by mail and over the counter in paperback book form (two 

volumes, publications listing and index) and as a set of microfiche.

Supplements for 1982, 1983, 1984, 1985, 1986, and for subsequent years since the last permanent catalog may be purchased by mail 

and over the counter in paperback book form.

State catalogs, "List of U.S. Geological Survey Geologic and 

Water-Supply Reports and Maps For (State)," may be purchased by 

mail and over the counter in paperback booklet form only.

"Price and Availability List of U.S. Geological Survey Publications," issued annually, is available free of charge in paperback booklet form only.

Selected copies of a monthly catalog "New Publications of the 

U.S. Geological Survey" are available free of charge by mail or may 

be obtained over the counter in paperback booklet form only. Those 

wishing a free subscription to the monthly catalog "New Publications 

of the U.S. Geological Survey" should write to the U.S. Geological 

Survey, 582 National Center, Reston, VA 22092.

Note.—Prices of Government publications listed in older catalogs, 

announcements, and publications may be incorrect. Therefore, the prices 

charged may differ from the prices in catalogs, announcements, and 

publications.