DEPARTMENT OF INTERIOR

U.S. GEOLOGICAL SURVEY

DATA ON THE GEOCHEMISTRY OF PELAGIC CLAY ON THE ABYSSAL PLAIN SURROUNDING

SHIMADA SEAMOUNT, EASTERN EQUATORIAL NORTH PACIFIC

by1 2 Walter E. Dean and James V. Gardner

Open-File Report 87-622

This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards. Use of trade names in this report is for descriptive purposes only and does not imply endorsement by the U.S. Geological Survey.

9U.S. Geological Survey, Box 25046, Denver Federal Center, Denver CO 80225 TI.S. Geological Survey, 345 Middlefield Road, Menlo Park, Ca 94025

TABLE OF CONTENTS

Page

Introduction................................................................Methods..................................................................... 4Results..................................................................... 4References Cited............................................................ 5

LIST OF ILLUSTRATIONSPage

Figure 1. Map shoving location of Shimada Seamount, sediment types, and key structural and physiographic features of the eastern equatorial North Pacific..................................................... 2

Figure 2. Map shoving bathymetry of Shimada Seamount and locations of coresused in this study................................................ 3

INTRODUCTION

The U.S. Geological Survey conducted a cruise on the R/V Sea Sounder (Cruise SI-79) to Shimada Seamount (17°N, 117°W; Figs. 1 and 2) to investigate the geologic, petrologic, magnetic, and bathymetric characteristics of the seamount as veil as the sediments on the surrounding abyssal plain. On this cruise, seismic-reflection, 3.5 KHz and 12 KHz bathymetric, gravity, and magnetic surveys were run over the seamount and surrounding area. Gravity and piston cores of pelagic clay were collected from five stations on the abyssal plain surrounding the seamount (Fig. 2; Table 1). The geologic, petrologic, and magnetic characteristics of Shimada Seamount were described by Gardner and others (1984). The purpose of this report is to present geochemical data on 46 samples of pelagic clay from the abyssal plain surrounding the seamount.

Table 1. Summary of cores collected from abyssal plain surrounding Shimada Seamount. G, gravity core; P, piston core

Water Depth

Core (m) Latitude Longitude Recovery

GlG3G5

P2P3

333

33

,910,810,913

,919,970

16°16°17°

17U18°

48'N27'N17'N

22'N08'N

117°117°117°

117°117°

56'W47'W07'W

42'W31'W

355240418

790680

cmcmcm

cmcm

pelagicpelagicpelagicat toppelagicpelagic

clayclay withclay with

clayclay

Mn nodules at topthin glass layer

The area around Shimada Seamount is of particular sedimentologic and geochemical interest because it is located just north of the north equatorial Pacific biosiliceous sedimentary province and at the eastern end of the metal-rich North Pacific ferromanganese nodule province (Fig. 1). One core recovered ferromanganese nodules, and bottom photography revealed that nodules are present over much of the area around the seamount. The sediments and ferromanganese nodules within this metal-rich province have been the subjects of intensive investigations as part of the Deep Ocean Mining Environmental Studies (DOMES) program (Bischoff and Piper, 1979). In addition, the observations that Shimada Seamount is a young volcanic feature, that altered basalt was recovered in core catchers of several cores, and that a thin layer of basaltic glass was recovered at the surface of one core suggest that volcanism that built the seamount may have affected the sediments around the base of the seamount and beyond.

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0% Ferromanganese

«i53TJ O Z

UJ

sin O

- )8. 5-- CD

COz

0> CD3 N9, °£ O^ «"^ CD T?o o

<u +jx -o <u c

a <o

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3 01 *-* 0) OQ. 3

bo ^c >-^ ^ Cu3C O

COi-H O

C XOJ 0)e j£ f* o »QJ <Un u

C -M JS,0) Oe a o o ob U 01 ^ Cu -^

C bO uCd C <U

iH W. C i-H <U

03 i-H S <M -rt O O r-l bO

C O3 U O 0.Sto toQ) i-HW 3 O<d o o c toS O

CO ->Hc

>M (0o cuC J=o *

(d z o o c

i-H IJOJbo-w

C CO rt (0> Vo

J= <U H J=

4^

o.(0 *W

3 bo

D. aV V I* Q) C/3 3

O.«4H 4-1 ft)o <u <uo j=CO *-*c - o o -o

>H Ct-> >o (Q CO C O 03 - O PO-< -vO

CO I-H

*- < Cto

« 0101 a; » <U *j esU -rt \O3 O) rH

4_><o <^> » a; co I-H m r^i \^o o n Q - JC ^«^ C7^a. m«) 01 rH U Q) bO-n 01o *a <v o. 3 * *O 4-> -n-M co 01

rt 00 O O\O i-H

11B'

00*

117*

00'

17*4

5'

Figu

re 2. Ma

p sh

owin

g ba

thym

etry

of

Shim

ada

Seam

ount

(G

ardn

er and

othe

rs,

1984

) an

d lo

cati

ons

of cores

used in

th

is study.

- 17

*00'

METHODS

Five cores of pelagic clay were collected from five different stations around Shimada Seamount (Fig. 2; Table 1). The recovered sections range in thickness from 240 to 790 cm (Table 1). The five cores (Gl, G3, G5, P2, and P3) vere sampled at 50-cm intervals for chemical analyses.

Samples vere air dried and ground in a ceramic mill to pass a 100-mesh (149um) sieve. From a total of 46 samples, four vere chosen at random for duplicate analyses. All 50 analytical samples (46 samples plus 4 duplicates) vere submitted in a random sequence to the analytical laboratories of the U.S Geological Survey, Denver. Total carbon (TC) and total sulfur (TS) vere measured using the LEGO induction-furnace gasometric method. Concentrations of ten major and minor elements (Si, Al, Fe, Mg, Ca, Na, K, Ti, P, and Mn) vere measured by X-ray fluorescence spectrometry (Taggert and others, 1981). Concentrations of 19 trace elements (B, Ba, Be, Co, Cr, Cu, Ga, La, Mo, Nb, Ni, Pb, Sc, Sn, Sr, V, Y, Zn, and Zr) vere determined by semiquantitive optical emission spectrometry (Miesch, 1976).

Because the samples vere air dried, concentrations of Na, Mg, and S as measured in the bulk sample are too high oving to Na, Mg, and SO, dissolved in interstitial vater and left as a residue on evaporation. To correct these values, Cl vas measured by specific ion electrode. We assumed that all of the Cl vas due to Cl dissolved in the interstitial seavater, and that this interstitial seavater contained the same proportions of Na, Mg, S, and Cl as average seavater. Contributions of Na, Mg, and S from interstitial seavater vere subtracted from the analytical values determined on the bulk sample.

RESULTS

Results of analyses for major, minor, and trace elements are presented in Table 2. Average values of major- and minor-element oxides, loss on ignition (LOI) at 900°C, and trace elements are given in Table 3 along vith values for Pacific pelagic clay, sediments from the DOMES manganese-nodule areas in the east central Pacific (Fig. 1), metalliferous sediment from Bauer Basin, and average basaltic glass dredged from Shimada Seamount.

REFERENCES CITED

Bischoff, J. L., and Piper, D. Z., 1979, Marine Geology and Oceanography of the Pacific Manganese Nodule Province: New York, Plenum Press, 837p.

Bischoff, J. L., Heath, G. R., and Leinen, M., 1979, Geochemistry of deep-sea sediments from the Pacific manganese nodule province: DOMES sites A, B, and C, in Bischoff, J. L., and Piper, D. Z., eds., Marine Geology and Oceanography of the Pacific Manganese Nodule Province: New York, Plenum Press, p. 397-435.

Circum-Pacific Council for Energy and Mineral Resources, 1985a, ManganeseNodules, seafloor sediment, and sedimentation rates of the Circum-Pacific region: American sociation of Petroleum Geologists, Circum-Pacific Maps.

___, 1985b, Plate-tectonic Map pf the Circum-Pacific Region: American Association of Petroleum Geologists, Circum-Pacific Maps.

Gardner, J. V., Dean, V. E., and Blakely, R. J., 1984, Shimada Seamount: An example of recent mid-plate volcanism: Geological Society of America Bulletin, v. 95, p. 855-862.

Heath, G. R., and Dymond, J., 1977, Genesis and transformation of metalliferous sediments from the East Pacific Rise, Bauer Deep, and Central Basin, northwest Nazca Plate: Geological Society of America Bulletin, v. 88, p. 723-733.

Miesch, A. T., 1976, Geochemical Survey of Missouri methods of sampling,laboratory analysis, and statistical reduction of data: U.S. Geological Survey Professional Paper 954-A, 39p.

Sayles, F. L., and Bischoff, J. L., 1973, Ferromanganoan sediments in the equatorial east Pacific: Earth and Planetary Science Letters, v. 19, p. 330-336.

Taggert, J. E., Jr., Lichte, F. E., and Wahlberg, J. S., 1981, Methods ofanalysis of samples using X-ray fluorescence and induction-coupled plasma spectroscopy, In, Lipman, P. V., and Mullineaux, D. R., eds., The 1980 Eruptions of Mount St. Helens: U. S. Geological Survey Professional Paper 1250, p. 683-692.

Table 2. Geochemical analyses of sediments on the abyssal plain surrounding Shimada Seamount.

Sample

P2-OOOcmP2-050cmP2-100cmP2-150cmP2-200cmP2-250cmP2-300cmP2-350cmP2-400craP2-450craP2-500cmP2-550cmP2-550cmP2-600cmP2-650cmP2-700cmP2-750cm

P3-OOOcmP3- 100cmP3-150craP3-200cmP3-250cmP3-300cmP3-300craP3-347cmP3-400cra

Gl-035cmGl-085craGl-135cmGl-185craGl-235cmGl-236cmGl-285craGl-335cm

G3-OOOcmG3-OOOcmG3-065cmG3-115craG3-165cmG3-215cm

G5-OOOcmG5-050cmG5- 100cmG5-100cmG5-147cmG5-200cmG5-250cmG5-297cmG5-350cm

% Si02

47.8947.2950.1949.6948.5948.7949.3948.6949.5949.5948.4947.9948.1947.4947.5946.6946.79

50.3950.6951.6949.1948.3949.1949.0949.5949.19

46.9943.4947.3949.0950.4950.1949.3949.49

46.6946.8948.4946.9945.3944.19

47.7942.6947.0946.9946.1947.4946.8946.9947.19

12.812.413.313.112.813.213.113.213.413.613.012.512.512.212.5-11.711.5

14.414.915.114.013.813.913.914.114.0

11.210.812.713.613.713.612.913.2

11.912.012.912.011.310.3

11.910.911.411.412.212.012.511.912.1

7.617.697.738.118.377.558.648.028.418.388.728.848.889.138.759.429.77

7.337.097.307.567.737.677.837.537.37

10.4012.1010.208.318.268.238.358.52

9.079.208.859.419.749.95

9.619.268.999.1410.409.73

10.209.789.91

% MgO

3.23.23.43.33.23.53.23.23.34.13.33.33.33.43.43.63.7

3.23.33.33.33.33.33.33.33.3

3.33.43.43.23.33.23.33.4

3.33.33.43.33.43.5

3.43.23.43.53.43.43.43.53.5

% CaO

1.411.411.461.631.551.381.861.601.501.421.411.431.461.611.451.821.79

1.501.661.671.461.461.491.471.531.51

1.371.501.471.911.661.651.491.34

1.701.711.671.632.202.12

1.561.581.571.521.631.571.471.581.63

*Na20

4.24.54.44.44.24.84.34.04.24.24.54.44.44.44.44.84.5

3.73.63.33.73.73.73.73.83.9

4.85.14.93.83.73.84.14.2

4.54.54.34.34.65.2

5.24.55.65.94.85.04.55.45.1

Table 2. (Continued)

Sample

P2 -000cmP2 -050cmP2-100cmP2-150cmP2-200cmP2-250cmP2-300cmP2-350cmP2-400cmP2-450cmP2-500cmP2-550cmP2-550craP2 -600cmP2-650cmP2-700cmP2-750cm

P3-OOOcmP3- 100cmP3-150cmP3-200cmP3-250cmP3-300cmP3-300cmP3-347cmP3-400cm

Gl-035cmGl-085cmGl-135cmGl-185cmGl-235cmGl-236cmGl-285cmGl-335cm

G3-OOOcmG3-OOOcmG3-065cmG3-115cmG3-165cmG3-215cm

G5-OOOcmG5-050cmG5- 100cmG5- 100cmG5-147cmG5-200cmG5-250craG5-297cmG5-350cmG5-400cm

* K20

2.692.612.782.782.752.592.782.582.592.492.462.442.452.472.432.352.32

2.952.933.072.872.832.882.882.902.87

2.432.262.662.822.882.852.772.53

2.482.512.442.382.382.39

2.442.272.342.412.492.492.602.452.512.56

Z Ti02

0.600.580.640.640.610.570.610.580.590.570.560.550.550.540.550.530.52

0.690.710.740.680.670.690.690.710.68

0.680.740.790.670.680.680.620.55

0.540.550.540.530.510.45

0.780.740.750.740.750.800.690.770.800.78

* P2°5

0.300.300.300.400.400.300.580.400.400.300.300.400.400.500.400.620.61

0.400.590.610.500.400.500.500.510.51

0.400.400.500.400.400.400.300.30

0.560.560.520.500.870.83

0.400.400.300.300.400.400.400.400.400.40

% MnO

1.211.191.021.301.441.191.200.951.321.271.281.301.281.281.211.431.76

0.890.871.001.891.751.741.731.491.45

0.891.580.941.931.621.581.481.45

1.901.921.231.181.451.66

1.160.970.850.840.901.071.261.031.121.17

% Total C

0.170.150.180.140.190.160.170.140.150.170.170.150.110.150.130.180.15

0.440.260.200.200.190.200.160.210.22

0.620.420.320.190.190.160.310.17

0.230.150.190.140.200.21

0.420.290.410.490.370.380.360.490.380.35

LOI-900

13.3014.4511.5011.7011.8012.5811.3012.5012.0512.2512.4612.9012.4012.8013.6012.8012.80

11.2010.9010.8011.2612.0410.9011.4011.1012.30

14.3515.0013.2010.9011.0011.0011.2012.10

12.8512.5012.7013.6013.4014.20

13.4520.2014.8213.7513.0612.9012.4112.8013.1013.40

Table 2. (Continued)

Sample

P2-OOOcmP2-050cmP2-100cmP2-150cmP2-200cmP2-250cmP2-300cmP2-350cmP2-400cmP2-450cmP2-500cmP2-550cmP2-550cmP2-600cmP2-650cmP2-700cmP2-750cm

P3-OOOcmP3- 100cmP3-150cmP3-200cmP3-250cmP3-300cmP3-300cmP3-347cmP3-400cm

Gl-035cmGl-085cmGl-135cmGl-185cmGl-235cmGl-236cmGl-285cmGl-335cm

G3-OOOcmG3-OOOcmG3-065cmG3-115cmG3-165cmG3-215cm

G5-OOOcmG5-050cmG5-100cmG5- 100cmG5-147cmG5-200cmG5-250cmG5-297cmG5-350cmG5-400cm

% Total S

0.390.390.460.380.350.370.340.380.360.280.360.460.390.420.380.450.46

0.270.190.310.420.340.310.420.360.27

0.350.460.330.370.350.280.330.38

0.400.450.320.420.410.45

0.290.270.410.400.290.330.270.340.330.25

ppm B

575749604954

120140543160

1301201201205649

1501401201301201406057

130

12015014012047

13049

140

1401605749120120

6054100130605745130120130

ppm Ba

51006500630063005700510063005700570079006500760065006500630065006100

560060006400760070007600490057007300

40005100530076004900900065005700

930079005100510065007300

4400430044005000500045003900490044004900

ppm Be

2.02.02.01.82.41.82.42.12.03.12.42.72.32.22.62.42.1

2.21.82.22.02.12.42.11.81.7

2.32.11.92.11.72.52.32.3

2.53.22.11.72.22.1

1.51.71.51.71.71.61.5'1.91.5'1.9-

ppm Ce

98841101008594

13099

1101401109691

13012012040

120130150150150130110140100

1204013014012013099

110

8415012082110100

11095961201101209840

100110

ppm Co

65808681100727281459952620

61885353

657277

130110120868791

588683

12076

1007981

568151376160

52495188456861958160

Table 2. (Continued)

Sample

P2-OOOcmP2-050cmP2-100craP2-150cmP2-200cmP2-250cmP2-300craP2-350cmP2-400cmP2-450cmP2-500cmP2-550cmP2-550cmP2-600cmP2-650craP2-700craP2-750cm

P3-OOOcmP3-100cmP3-150craP3-200cmP3-250craP3-300cmP3-300craP3-347craP3-400cm

Gl-035cmGl-085craGl-135craGl-185craGl-235cmGl-236cmGl-285craGl-335cm

G3-OOOcmG3-OOOcraG3-065cmG3-115cmG3-165cmG3-215cra

G5-OOOcraG5-050cmG5-100craG5-100cmG5-147cmG5-200craG5-250cmG5-297cmG5-350cmG5-400cm

ppm Cr

2927402434323128283739292833342219

545255404040444445

4045484833373627

263731192320

41433452404441434347

ppm Cu

410360400350360370340360320420350360400350350360 '320

220250280480440410400400360

250320320450360450400410

420520360320350360

250220200250250250290280250250

ppm Ga

2435283529232529183325262626272421

272626282427262327

1919202922252323

263520182122

19211823221919252322

ppm La

66596271696511077789579737399739899

6492

10011010099709780

64687512089996663

831209074

120120

57505362585755616064

ppm Mo

1433203233364437636633383953916143

51316362836341622

225

2428362631

434634213546

2617543463

ppm Nb

11101311119

11118

191312121218149

121515151419111314

1413131811131110

1215158

139

1079

13109

12141012

Table 2. (Continued)

Sample

P2-OOOcmP2-050cmP2-100cmP2-150cmP2-200cmP2-250cmP2-300cmP2-350cmP2 -400cmP2-450cmP2-500cmP2-550cmP2-550cmP2-600cmP2-650cmP2-700cmP2-750cm

P3-OOOcmP3-100cmP3- 150cmP3-200cmP3-250cmP3-300cmP3-300cmP3-347cmP3-400cm

Gl-035cmGl-085cmGl-135cmGl-185cmGl-235cmGl-236cmGl-285cmGl-335cm

G3-OOOcmG3-OOOcmG3-065cmG3-115cmG3-165cmG3-215cm

G5-OOOcmG5-050cmG5- 100cmG5-100cmG5-147cmG5-200cmG5-250cmG5-297cmG5-350cmG5-400cm

ppm Nd

704071755756130957995896184

12090

110140

641001101001609672

12083

605263

1701201007056

7613012090

150130

48584761404056406358

ppm Ni

15013011012032012012012082

110778982971108587

110120130740560590480460490

7511075

570380540340110

6007509670

100120

83778610075738210090

100

ppm Pb

3534403935263632295939414037415744

403537705563674146

4459525437404152

625935305356

44503645574648515351

ppm Sc

16161816181520161619 16151520161616

192122222118152017

1514151918211615

132217141813

14131316131313131316

ppm Sn

7.14.58.76.17.85.94.55.94.79.48.16.47.08.26.47.07.2

4.44.96.87.98.55.39.57.15.2

8.06.67.27.86.55.86.77.0

2.56.57.35.76.76.7

5.66.54.36.65.26.87.75.75.93.5

ppm Sr

330340430280420350330330340410400420420420380440440

290340350500480400330410330

310360330370320390440350

380580400350490510

270280260330340300300340300280

10

Table 2. (Continued)

Sample

P2-OOOcmP2-050cmP2-100cmP2-150cmP2-200cmP2-250cmP2-300cmP2-350cmP2-400cmP2-450cmP2-500cmP2-550cmP2-550cmP2-600cmP2-650cmP2-700cmP2-750cm

P3-OOOcmP3-100cmP3-150cmP3-200cmP3-250cmP3-300cmP3-300cmP3-347craP3-400cm

Gl-035cmGl-085cmGl-135cmGl-185cmGl-235cmGl-236cmGl-285cmGl-335cm

G3-OOOcmG3-OOOcmG3-065cmG3-115cmG3-165cmG3-215cm

G5-OOOcmG5-050cmG5-100cmG5-100cmG5-147craG5-200cmG5-250cmG5-297cmG5-350cmG5 -400cm

ppm V

8691858595821109188

110879590

1101109589

9710010012089120909898

8611095

110921207893

1101408673

11098

818183100797881999296

ppm Y

808277

10095811509890

13091938212092

110120

100140130150130150110130130

828791

1801101407779

12016011083150140

73677184706975847794

ppm Yb

6.78.46.77.5

10.012.012.08.17.4

12.09.3

10.08.811.09.49.89.0

8.99.9

10.011.09.9

14.08.79.811.0

6.16.26.615.07.213.08.47.2

13.017.09.57.7

15.015.0

4.66.04.37.06.25.05.66.36.28.1

ppm Zn

160160150120140120140150120220120170130150180170160

110150140190180190150150190

140150150190140150150160

210210140150150200

130150120140140130120160150140

ppm Zr

200260270350210210360220240340250210260340370260250

370290300300250380220230320

220180230360220370210210

170410240180220250

180190170230190140180190160220

11

Table 3. Average concentrations of major-element oxides and trace elements for Pacific pelagic clay, sediments from DOMES sites A, B, C, DOMES site C, all sediment samples from this study, sediments from core P2, and surface sediments from five stations on abyssal plain surrounding Shimada Seamount, sediments from Bauer Basin, and basaltic glass from Shimada Seamount.

Oxideor

Element

Pacific DOMESPelagic Sites. Clay A+B+C

DOMES Site

Shimadaall

C Samples

ShimadaCore P2

ShimadaSurface Samples

Bauer2 Basin

Shimada glass

Percent

SiO«Al«6-FefofMgOCaONa 0K20TiO«P2°5MnO3

LOI

Sum

T-C02T-S

ppm Bppm Bappm Beppm Coppm Crppm Cuppm Moppm Nippm Pbppm Scppm Srppm Vppm Yppm Zn

Sources

54.916.67.73.4.7

1.32.7.78.25.56

1.00 ~

1003900 11364

23010

2103425

710120150165

of data:

2 Bischoff and

50.411.56.93.12.63.83.2.67.46.97

12.6

96.2

2.1

15433003.310153

51019

2805025

30099

110163

others,J __!__££

50.714.57.63.22.32.93.2.72.42

1.2012.4

99.1

1.04

14539003.511653

60024

3406121

32010097

160

19791 rtT-5

48.112.78.83.41.64.42.6.64.44

1.3012.7

96.7

.89

.36

Parts per

9660002.17337

34027

2104517

37096100150

48.412.78.53.41.54.42.6.58.41

1.3012.6

96.4

.59

.39

million

7863002.36730

36043

1203917

3809499

150

48.012.48.83.31.54.52.6.66.41

1.2013.0

96.4

1.41.34

10557002.15938

31013

2004515

3209291150

1 rtTT

44.18.813.04.32.3.74

2.3.50 5.60

__ *

_3300 960 750 410

52.414.511.25.899.782.65.80

2.00.22

99.85

__

Average of 4 basaltic glass samples dredged from Shimada Seamount (Gardner and others, 1983).

12