The distribution of rare earth and minor elements in manganese nodules and sediments from the equatorial and S.W. Pacific

The distribution of rare earth and minor elements in manganese nodules and sediments from the equatorial and S.W. Pacific

Lithos, 20 ( 1 9 8 7 ) 9 7 - 1 1 3 97 Elseviei Science Publishers B.V., Amsterdam - Printed in The Netherlands The distribution of rare earth and m...

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Lithos, 20 ( 1 9 8 7 ) 9 7 - 1 1 3

97

Elseviei Science Publishers B.V., Amsterdam - Printed in The Netherlands

The distribution of rare earth and minor elements in manganese nodules and sediments from the equatorial and S.W. Pacific G.P. GLASBY 1 , R. GWOZDZ 2 , H. KUNZENDORF 2 , G. FRIEDRICH 3 and T. THIJSSEN 3

IN.Z. Oceanographic Institute, D.S.LR., Private Bag, Kilbirnie, Wellington (New Zealand) 2Ris~ National Laboratory, Postbox 49, DK-4000 Roskilde (Denmark) 3Abteilung fiir Angewandte Lagerst~ttenlehre der R WTH, Siisterfeldstr. 22, D-51O0 Aachen (Federal Republic of Germany]

LITHOS

0

Glasby, G.P., Gwozdz, R., Kunzendorf, H., Friedrich, G. and Thijssen, T., 1987. The distribution of rare earth and minor elements in manganese nodules and sediments from the equatorial and S.W. Pacific. Lithos, 2 0 : 9 7 - 1 1 3 . 62 manganese nodules and 17 associated sediments from the equatorial and S.W. Pacific have been analyzed for a number of elements, including the rare earth elements (REE), by instrumental neutron activation. Sc, Co, As, Hf, Th and REE occur in higher concentrations in S.W. Pacific than in equatorial Pacific nodules, reflecting the higher iron content of the S.W. Pacific nodules. These elements are probably incorporated nondiscriminantly into the iron oxyhydroxide structure by direct sorption from seawater because they are too large to be incorporated into the manganese oxide structure. The highest Ce/La ratios are also found in the S.W. Pacific nodules. This may result from the fact that these nodules lie beneath the path of the fast flowing, well-oxygenated Antarctic Bottom Water (AABW) which facilitates oxidation of Ce to the tetravalent state. If so, this supports the idea that the Ce/La ratio of manganese nodules is an important redox indicator. Negative cerium anomalies were noted for nodules from Areas F and G and can be interpreted on the same model. The REE contents in equatorial Pacific siliceous oozes and S.W. Pacific red clays are similar on a carbonate-free basis. The Ce/La ratio of the S.W. Pacific red clays is, however, much higher than that of the equatorial Pacific sediments, possibly reflecting the preferential oxidation of Ce to the tetravalent state beneath the AABW. There appears to be no systematic relationship between the REE abundance in the nodules and their associated sediments, although absolute REE abundances are higher in nodules than in their associated sediments. Nodules with the highest Ce/La ratios are, however, found on sediments with the highest Ce/La ratios. The principal difference in the REE distribution pattern of the nodules and sediments lies in the well-known cerium anomaly which is positive to slightly negative for nodules and always negative for sediments. (Received June 5, 1986; accepted July 29, 1986)

Introduction

In a series o f p u b l i c a t i o n s (Glasby, 1 9 7 3 ; Glasby et al., 1 9 7 8 ; R a n k i n a n d G l a s b y , 1979), d a t a o n t h e d i s t r i b u t i o n o f t h e rare e a r t h e l e m e n t s ( R E E ) in m a n ganese n o d u l e s a n d t h e i r associated s e d i m e n t s f r o m various m a r i n e e n v i r o n m e n t s have b e e n p r e s e n t e d . Because o f t h e difficulties o f analysis, this w o r k was b a s e d o n t h e s t u d y o f o n l y 27 n o d u l e s a n d 14 s e d i m e n t sampies. F r o m this, R a n k i n a n d G l a s b y ( 1 9 7 9 ) s u g g e s t e d 0024-4937/87/$03.50

© 1987 Elsevier Science Publishers B.V.

t h a t t h e r e are significant d i f f e r e n c e s in the rare e a r t h abundance between manganese nodules from the e q u a t o r i a l a n d S.W. Pacific a n d t h a t s u c h d i f f e r e n c e s could be related to d i f f e r e n c e s in t h e biological prod u c t i v i t y in t h e t w o regions. Subsequently, a number of papers on the REE d i s t r i b u t i o n in m a r i n e samples has a p p e a r e d : in m a n g a n e s e n o d u l e s ( M i c h a r d a n d R e n a r d , 1 9 7 5 ; H o f f e r t et al., 1978; A d d y , 1979; G i r i n et al., 1979; C o u r t o i s a n d Clauer, 1980; Elderfield and

-

98 Greaves, 1981; Elderfield et al., 1981a,b; Haynes et al., 1981; Lyle, 1981; Moore et al., 1981; Piper and Wflliamson, 1981; Tlig, 1982; Fleet, 1983, 1984; Aplin, 1984; Calvert and Piper, 1984; Dymond et al., 1984; Murphy and Dymond, 1984; von Stackelberg et al., 1984; Wang et al., 1984; De Carlo and McMurtry, 1985; Ingri, 1985; Frost et al., 1986); - in manganese micronodules (Addy, 1979); in synthetic manganese oxides (Mellin, 1981); - in marine sediments (Courtois and Hoffert, 1977; Hoffert et al., 1978 ; Addy, 1979;Courtois and Clauer, 1980; Chamley and Bonnot-Courtois, 1981 ; Elderfield et al., 1981a; Tlig, 1982; Tlig and Steinberg, 1982; Zhao et al., 1983; Fleet, 1984;Murphy and Dymond, 1984; Thomson et al., 1984; Lea et al., 1985; Marchig et al., 1985; Palmer, 1985; Shaw and Wasserburg, 1985; Palmer and Elderfield, 1986); in phosphorites (Kolodny, 1981; Burnett et al., 1983; O'Brien and Veeh, 1983;McArthur and Walsh, 1984; Jonasson et al., 1985; Shaw and Wasserburg, 1985 ; Staudigel et al., 1985); - in submarine basalts (Fleet et al., 1976; Ludden and Thompson, 1978, 1979; Bonnot-Courtois, 1980; Desprairies and Bonnot-Courtois, 1980; Chamley and Bonnot-Courtois, 1981); - in metalliferous sediments (Dymond et al., 1977; Bonatti, 1981; Bonnot-Courtois, 1981 ; Marchig et al., 1982; Robertson and Boyle, 1983; Kunzendorf et al., 1984; Stoffers et al., 1985; Ruhlin and Owen, 1986); - in hydrothermal fluids (Klinkhammer et al., 1983; Michard et al., 1983; Michard and Albar6de, 1986); - in seawater (Elderfield and Greaves, 1982; Bruland, 1983; de Baar et al., 1983, 1985; Fleet, 1984; Stordal and Wasserburg, 1986); in pore water (Ridout and Pagett, 1984); and - in river water (Martin et al., 1976; Keasler and Loveland, 1982 ; Hoyle et al., 1984). In spite of this. many of the data on manganese nodules come from limited areas, particularly in the equatorial N. Pacific nodule belt, so that regional trends in the REE abundance of nodules on an oceanwide scale are still not possible. Rare earth data on manganese nodules are valuable in that they give additional boundary conditions for any hypothesis of nodule genesis. In particular, three factors can be considered: the absolute REE abundance which is dependent on the rate of deposition of the REE from seawater relative to that of the major phases of the nodules; the REE distribution pattern which gives some

indication of the mode of uptake of the REE into the manganese oxide structure from seawater (hydrolysis parameters may be important in this respect cf. Kumar, 1984); and - the cerium enrichment (Ce/La ratio) which is a possible redox indicator. The object of this paper is to define regional trends in REE distribution further utilizing additional data on nodules and sediments from a series of diverse but well-studied environments taken along a N - S equatorial Pacific transect (and including material from the Aitutaki Passage in the S.W. Pacific and from the Peru Basin).

Sampling

and

analytical

methods

62 manganese nodules and 17 associated sediments were sampled during cruises SO-04 and SO-11/2 of R.V. "Sonne" (Peru Basin) and SO-06 of R.V. "Sonne" (equatorial Pacific transect and Aitutaki Passage). The material from the equatorial Pacific transect was collected as part of the I.C.I.M.E. (International Cooperative Investigations of Manganese Nodule Environments) Project. The distribution, morphology, mineralogy and geochemistry of these nodules, the geochemistry of the sediments and the geology of the individual study areas has been described in detail (Friedrich et al., 1981, 1983; Stoffers et al., 1981 ; Thijssen et al., 1981 ;Glasby and Thijssen, 1982a,b; Glasby et al., 1983) providing valuable background for this work. It should be noted that Areas C - G and the Peru Basin lie in the equatorial Pacific zone of high productivity and nodules from these areas are characterized by high Mn/Fe ratios and high contents of Ni, Cu and Zn with 10 • manganite as the principal manganese oxide phase compared to those from Area K in the Aitutaki Passage, a low productivity zone associated with the subtropical anticyclonic gyre, which contain ~-MnO2 as the principal manganese oxide phase. Within individual areas, nodules were selected from a series of size classes from individual stations to see if systematic trends in nodule composition are apparent. Sediment samples were taken at various depths from box or spade cores in each area or represent bulk samples (i.e. from the upper 40 mm of the core). Fig. 1 shows the locations of the sample areas. About 400-600 mg of manganese nodule material packed into polyethylene containers were irradiated

99

p HAWAII IS. ul

20 °

IIC f

f

J l i d

GALAPACK)SIS

IIF

Peru Basin

mG J

~

FIJI

• TAHI TI

20 °

180°W

160 °

140 °

120 °

100 °

80*

Fig. 1. Schematic map showing locations of sample areas. for 30min. in the Ris~6 research reactor DR3. The neutron flux at the irradiation site was 4 X 1013 n cm -2 s-1 , with a thermal- to fast-neutron flux ratio of about 1000. Because of the relatively high Co contents in manganese nodules, a rather low integrated neutron flux had to be applied to avoid a high gamma-ray background. Standardization and monitoring of subsequent decay conditions was achieved by the SgFe activity from Fe2Oa (single-element comparator). After irradiation, the samples were cooled for 2 - 3 days and then measured for 1 h with a large Ge(Li) detector coupled to a multichannel analyzer. Na, Br, As, La, Ce and Sm were determined by this measurement. After 7 to 14 days decay, Cr, Fe, Co, Zn, Eu, Tb, Yb, Lu, Hf, Th and other elements were determined by counting for 2 to 6 h. The data processing was undertaken by means of a system of programs developed for instrumental neutron activation analysis of geological and environmental samples by a modified single-comparator method (Girardi et al., 1965). A more detailed description of the method used for the analysis including intensity calculations and computer programmes will be given elsewhere. Detection limits for the analysis of manganese nodules and deep-sea sediments were estimated to be 50 ppm Na, 0.35% K, 0.5% Ca, 0.1 ppm Sc, 9 ppm Cr,0.15% Fe,2.5 ppm Co, 60 ppm Zn, 5 ppm As, 4 ppm Br, 75 ppm Rb, 550 ppm Sr, 0.5 ppm Sb, 2 ppm Cs, 300 ppm Ba, 1 ppm La, 2.5 ppm Ce, 20 ppm Nd, 0.05 ppm Sm, 1 ppm Eu, 1.5 ppm Tb, 0.5 ppm Yb, 0.1 ppm Lu, 1 ppm Hf and 1 ppm Th.

Results

Manganese nodules A complete listing of the nodule compositional data is given in Appendix A and a summary of the average composition within each area is given in Table 1. On a regional scale, the most obvious trend is the higher contents of Sc, Cr, Fe, Co, As, Hf, Th, REE and Ce/La and lower contents of Zn and Ba in nodules from the low productivity zone (Area K, Aitutaki Passage) compared to those from the zone of equatorial high productivity (Areas C - G and the Peru Basin). This confirms the earlier REE data obtained by Rankin and Glasby (1979). Within the equatorial high productivity zone, compositional trends are much less clear. With exception of Cr which is associated with the silicate phase of nodules (Glasby et al., 1974), these element patterns are similar to those established by Glasby and Thijssen (1982a) in which the biogenic elements (Mn, Ni, Cu, Zn and Ba) are preferentially incorporated in nodules from the equatorial Pacific high productivity zone whereas elements such as Sc, Co, As, Hf, Th and REE are preferentially associated with the iron oxyhydroxide phase of the nodules. This observation is supported by the correlation matrix for the total nodule data (Table 2) which confirms the association of these elements in nodules with Fe. Sb correlates with Mn as previously observed by Moore et al. (1981). An enrichment sequence of elements

100 TABLE

1

Average element contents

o f n o d u l e s f r o m s t u d y a r e a s C, F , G a n d K a n d P e r u B a s i n ( n u m b e r

o f s a m p l e s in p a r e n t h e s e s )

Element

Area C (9)

Area F (14)

Area G (11 )

Area K (16)

Peru Basin (12)

Na (%) K (%) Sc ( p p m ) Cr ( p p m ) Fe (%) Co (ppm) Zn (ppm) As (ppm) Br ( p p m ) Sb (ppm) Ba ( p p m ) La (ppm) Ce ( p p m ) Nd (ppm) Sm (ppm) Eu (ppm) Tb (ppm) Yb (ppm) Lu (ppm) Hf(ppm) W (ppm) Th (ppm)

2.27 + 0.16 0.80 ± 0.14 10.0 ± 0.9 15 ± 1 0 4.74 ± 0.39 2150 ± 326 1200 ± 251 56 ± 7 20-+ 5 40.0 ± 2.5 2190 ± 481 93 ± 10 3 4 4 -+ 7 6 134 + 33 33.3 + 6.2 7.8 ± 1.4 4.0 ± 0.9 1 2 . 9 -+ 2.1 1 . 8 -- 0 . 4 5 ± 1 6 0 -+ 8 27 ± 6

1.92 - 0.41 0.69 ± 0.21 1 0 . 0 -+ 0 . 2 8 + 4 5.94 ± 1.10 1040 ± 129 1380 ± 247 4 2 -+ 7 15 ± 7 33.3 ± 6.6 1 3 6 0 -+ 531 61 ± 6 8 8 + 13 6 5 ± 13 15.4 + 2.4 4.0 ± 0.5 2.4 ± 0.3 9 . 3 -+ 0 . 7 1.5 -+ 0 . 2 4 ± 1 44 ± 7 5 ± 2

1.76 + 0.13 0.70 ± 0.26 11 -+ 4 2 9 -+ 3 6 10.50 + 2.60 998 ± 184 1240 ± 362 8 2 -+ 1 8 15-+ 6 2 5 . 1 ± 5.3 1 4 4 0 -+ 4 3 8 1 0 0 -+ 3 0 151 -+ 9 0 87 + 30 1 9 . 3 + 8.2 4 . 9 -+ 1.3 2.9 ± 1.0 13.0 ± 3.3 2 . 0 -+ 0 . 5 6 + 1 46 ± 10 4 ± 2

1.59 + 0.20 O.61 -+ 0 . 1 5 13.7 + 1.6 69 ± 28 16.3 ± 2.0 4 2 0 0 -+ 9 8 0 3 0 7 -+ 1 2 6 1 3 9 +- 1 6 18 ± 7 27.4 ± 3.4 594 ± 176 1 6 9 -+ 18 1360 + 218 173 ± 52 3 5 . 1 + S.S 8 . 9 ± 1.0 4 . 5 -+ 1 . 0 17.8 + 2.2 2 . 7 -+ 0 . 5 16 + 4 38 ± 14 5 4 + 12

2 . 4 9 -+ 0 . 3 7 0 . 5 8 -+ O . 1 0 6 . 7 -+ 1.3 7 --- 5 4 . 4 0 +- 1.3 486 ± 233 1 5 7 0 -+ 2 4 0 55 -+ 12 28-+ 8 4 3 . 0 -+ 7 . 2 2900 ± 567 55 +- 13 1 1 2 -+ 3 6 4 6 -+ 11 1 2 . 3 +- 2 . 8 3.0 ± 0.7 1.9 -+ 0 . 4 8 . 7 -+ 1.9 1.4 ± 0.3 4 ± 1 59 + 9 7 -+ 2

in Area C nodules compared to Area K nodules shows the different pattern of associations of elements in nodules; the sequence is Zn (3.9) > Ba (3.7) > Sb (1.5) > Na (1.4) > K (1.3) > Br (1.2) > Sc (0.72)> La (0.55) > Co (0.51) > Th (0.50) > As (0.40) > Hf (0.30) > Fe (0.29) > Ce (0.25) > Cr (0.22). In addition, there is in general a systematic trend in element composition from Area K to Area F (i.e. approaching the zone of equatorial high productivity) similar to that previously noted by Glasby and Thijssen (1982b). Within individual areas, no systematic trends are apparent (cf. Appendix A). Variations in nodule composition are smaller than those between areas and no statistically meaningful systematic variation with nodule size is detected. This is in part caused by the limited number of samples analyzed from each area. The average shale-normalized rare earth abundance patterns of the nodules from each area are given in Fig. 2. These patterns are similar to those previously noted for S.W. Pacific nodules by Rankin and Glasby (1979) and show the well-known Ce enrichment; they are also similar for nodules from each of the study areas. The even nature of these patterns and the absence of any real fractionation of the REE's with atomic number suggest that, with the exception of

cerium, the REE's are indiscriminately incorporated into manganese nodules (i.e. without any marked crystal-chemical control). The principal difference lies in the cerium anomaly (compared to the value obtained by interpolation between normalised La and Nd; Elderfield et al., 1981a). Nodules from Area K show a pronounced positive anomaly whereas those from Area C and the Peru Basin show only a weak positive anomaly and those from Areas F and G a negative anomaly. Not only are nodules from Area K characterized by higher REE abundances therefore but they also display a much more pronounced positive Ce anomaly.

Sediments The sediment compositional data are given in Appendix B and a summary of the average composition of sediments within each area is given in Table 3. Too few sediment samples from each area have been analyzed to give a meaningful assessment of the variation in sediment composition within individual areas (cf. Appendix B). Such variations are further complicated by variations in the CaCOa contents of the sediments (cf. Glasby et al., 1979). Variations in

-0.61

-0.39 0.74

Cr

--0.68 0.79 0.72

Fe

-0.53 0.63 0.59 0.77

Co

0.55 --0.82 --0.82 --0.84 --0.86

Zn -0.53 0.66 0.72 0.94 0.82 --0.81

As 0.48 --0.43 n.c. --0.29 n.c. 0.33 n.c.

Br

n.c. = c o r r e l a t i o n n o t s i g n i f i c a n t at 9 5 % c o n f i d e n c e level.

Na Sc Cr Fe Co Zn As Br Sb Ba La Ce Nd Sm Eu Tb Yb Lu Hf W

Sc 0.77 --0.70 --0.46 --0.65 --0.40 0.55 --0.48 0.40

Sb 0.62 --0.71 --0.53 --0.69 --0.56 0.58 --0.54 0.43 0.63

Ba

C o r r e l a t i o n m a t r i x f o r e l e m e n t s in m a n g a n e s e n o d u l e s b a s e d on 62 s a m p l e s

TABLE 2

--0.57 0.71 0.67 0.92 0.87 --0.84 0.96 n.c. --0.49 --0.56

La -0.48 0.64 0.69 0.85 0.94 --0.86 0.91 n.c. --0.36 --0.53 0.92

Ce -0.36 0.61 0.56 0.72 0.79 --0.68 0.77 n.c. n.c. --0.47 0.87 0.82

Nd -0.32 0.61 0.48 0.64 0.78 --0.69 0.71 n.c. n.c. --0.40 0.83 0.76 0.90

Sm -0.44 0.66 0.52 0.71 0.85 --0.74 0.76 n.c. --0.32 --0.46 0.89 0.84 0.93 0.94

Eu -0.40 0.56 0.49 0.64 0.74 --0.69 0.67 n.c. --0.27 --0.44 0.78 0.69 0.79 0.83 0.83

Tb --0.55 0.65 0.52 0.84 0.82 --0.74 0.87 n.c. --0.44 --0.47 0.95 0.83 0.85 0.85 0.90 0.79

Yb -0.53 0.61 0.45 0.82 0.75 --0.68 0.84 n.c. --0.41 --0.48 0.90 0.80 0.77 0.78 0.84 0.64 0.95

Lu --0.56 0.72 0.73 0.94 0.84 --0.84 0.93 n.c. --0.43 --0.56 0.91 0.92 0.77 0.69 0.75 0.67 0.83 0.78

Hf 0.45 --0.62 --0.56 --0.61 --0.33 0.47 --0.42 0.46 0.46 0.74 --0.40 --0.40 --0.34 n.c. --0.26 --0.31 --0.31 --0.29 --0.55

W --0.37 0.61 0.68 0.75 0.91 0.81 0.83 n.c. n.c. --0.41 0.86 0.95 0.85 0.79 0.86 0.71 0.79 0.73 0.88 --0.35

Th

102

N

~o --K

~s --F ~Peru Bosln

I

i

Lo

J

1

Pr

Ce

J

i

Pm

hid

i

i

Eu

i

i

I

Tb

$m

C~

I

14o

Oy

I

I

i

Trn

Er

Lu Yb

10

// / t

/

~s ,

~

F

~

-

o--O--F

~

-cG

2

1

0.S

0.2

i

0.1 Lo

Pr Ce

Pm Nd

Eu Sm

I

Cx:l

I

I

Ho

Tb Oy

I

I

Trn Er

I Lu

Yb

Fig. 2. Average shale - normalized REE patterns of manganese nodules (above) and associated sediments (below) from each of the sample areas.

sediment composition within individual areas will therefore not be considered further. A fuller discussion of the trace element geochemistry of sediments from these areas has, however, been presented by Stoffers et al. (1981). To date, little work has been carried out on the determination of REE in marine sediments (Glasby et al., 1978; Rankin and Glasby, 1979) or the compositions of equatorial and S.W. Pacific sediments

(Bischoff et al., 1979; Glasby et al., 1979, 1985; Hein et al., 1979; Stoffers et al., 1981). From the data presented in Table 3, it is seen that carbonate acts as a diluent. Area D sediments, for example, are depleted in all elements except Mn (which may be incorporated in the form of micronodules) and St. Area F and G sediments which contain lower carbonate contents than Area D sediments have compositions more similar to those of Area C, although displaying higher contents of Mn, As, Sr and Sb. The higher Mn contents may again reflect the incorporation of micronodules in the sedimentary material. Sediments from the Peru Basin are similar in composition to those from Area C for many elements which may reflect the similarity of sediment type, siliceous oozes being present in both environments. These data taken together show some measure of similarity of sediments from the equatorial Pacific high productivity zone with a major factor influencing the composition being the carbonate content (cf. Stoffers et al., 1981). In fact, Stoffers et al. (1981) have suggested that these equatorial Pacific sediments represent (on a carbonate-free basis) a discrete geochemical province. Comparison of sediments from Area C with those from Area K shows that sediments from the equatorial belt of high productivity (Area C) contain higher contents of Ni, Cu, Br, Cs and Ba whereas those from the S.W. Pacific red clay area (Area K) contain higher contents of Cr, Mn, Fe, Co, Zn, As and higher Ce/La ratios. The contents of Na, Sc, Rb, Sr, Sb and REE in sediments from the two regions are similar. Of the element ratios, the Mn/Fe and Ce/La ratios of the S.W. Pacific red clays are higher than those of equatorial Pacific sediments. This is in accord with the more oxidizing conditions prevailing at the sediment-water interface due to the passage of Antarctic Bottom Water (AABW) and the low sedimentation regime in the Aitutaki Passage. The enrichment sequence of elements in Area C sediments relative to Area K sediments lies in the order Ba (24.3) > Cs (1.7) > Br (1.6) > Rb (1.3) > Na (1.1) = Sc (1.1)> La (1.0) > Sb (0.9) > Th (0.7) = Hf (0.7) > Fe (0.5) = Ce (0.5) > Co (0.3) = Cr (0.3) > As (0.2). The considerable enrichment of Ba in equatorial Pacific sediments compared with S.W. Pacific red clays reflects the occurrence of barite there as first noted by Arrhenius et al. (1957) (cf. Goldberg and Arrhenius, 1958). This sequence of enrichment reflects the fact that the equatorial Pacific sediments are characterized by higher contents of authigenic transition elements,

103

TABLE 3 A v e r a g e e l e m e n t c o n t e n t s i n s e d i m e n t s f r o m a r e a s C, D, F , G a n d K a n d P e r u B a s i n ( n u m b e r o f s a m p l e s i n p a r e n t h e s e s ) Element

Area C (3)

Area D (1)

Area F (2)

Area G (2)

Area K (7)

Peru Basin (2)

Na (%) Ca (%) Sc ( p p m ) Cr ( p p m ) F e (%) Co ( p p m ) As (ppm) Br ( p p m ) Rb (ppm) Sr ( p p m ) Sb ( p p m ) Cs ( p p m ) Ba ( p p m ) La ( p p m ) Ce ( p p m ) Nd (ppm) Sm (ppm) Eu (ppm) Tb ( p p m ) Yb ( p p m ) Lu (ppm) Hf(ppm) Th (ppm)

3.6 + 0 . 5 6 0.70 ± 0.42 2 4 . 1 :i: 2 . 0 4 9 ± 12 3.86 ± 0.34 4 6 ± 41 5 ± 3 126 ± 6 56.6 ± 33.8 1.5 ± 0 . 7 5 ± 2 8143 ± 6899 69 ± 44 7 5 ± 15 69 ± 47 17.6 ± 9.3 4.5 ± 2.6 2 . 8 ± 1.9 9 . 0 ± 5.2 1.5 + 0 . 8 4±0 10 ± 3

1.32 38.4 3.2 5 0.37 12 49 5.5 1290 0.09 1030 11 8 7 3.5 0.7 0.4 1.5 0.2 -1

3.98 + 0.58 4.98 ± 5.32 1 4 . 6 ± 1.3 16 + 1 2.38 ± 0.22 86 ± 8 8 ± 1 130 + 20 493 ± 127 1.2 -+ 0 . 7 3895 ± 460 70 ± 4 42 ± 3 73 + 1 1 9 . 5 ± 1.1 4.5 ± 0.2 3 . 3 ± 0.1 1 2 . 0 ± 0.1 1.9 ± 0.1 250 4 + 0

3.31 ± 2 . 2 4 16.58 ± 19.54 10.9 ± 9.5 25 ± 24 5.17 ± 4.94 9 6 -+ 7 9 20 ± 17 95 + 47 2.6 ± 2.5 3390 ± 1952 7 0 ± 61 46 5 40 61 5 52 18.1 ± 1 6 . 2 3.8 ± 3 . 2 2.7 5 2.2 9.4 ± 7.7 1.6 ± 1.4 2±2 2 5 1

3.14 ± 0.86 3 . 9 5 -+ 2 . 6 6 2 2 . 2 -+ 1.7 154 ± 155 7.79 ± 2.06 137 5 47 21 + 6 78 ± 27 42.2 ± 23.3 562 5 309 1.6 5 0.5 3 5 1 3 3 5 ± 51 6 6 + 61 140 ± 46 6 9 ± 25 17.1 + 6 . 3 3 . 8 ± 1.4 2.2 ± 0 . 9 6.9 5 3.2 1.1 ± 0 . 4 5±2 14 5 5

3.86 ± 0.91 7.57 ± 5.56 2 0 . 4 ± 5.7 37 ± 6 3 . 1 6 +- 0 . 8 5 53 +- 2 5 5 1 175 5 4 8 41.9 5 18.5 404 5 113 1.5 5 0 . 2 5 ± 1 9550 ± 2899 37 ± 9 40 5 9 33 ± 1 8.1 -+ 1.6 2 . 0 -+ 0 . 5 1.4 5 0 . 4 5.7 5 1.2 1.0 5 0 . 2 3 ± 1 6 ± 2

barite and siliceous material whereas the Aitutaki Passage sediments display higher contents of clays and volcanoclastic material (i.e. the difference between siliceous ooze and red clay) (cf. Stoffers et al., 1981). Co and As appear to be associated with Fe and Cr in the aluminosilicate phase. Rankin and Glasby (1979) have previously suggested that Rb and Cs are associated principally with the aluminosilicate phase but these elements appear to occur in higher concentrations in the equatorial Pacific siliceous oozes rather than the S.W. Pacific red clays. The average shale-normalized rare earth abundance patterns of the sediments are given in Fig. 2 (cf. Rankin and Glasby, 1979; Elderfield et al., 1981a). The principal difference in rare earth contents and distribution patterns of the nodules and the sediments lies in the negative cerium anomaly of the sediments.

Nodule-sediment relationships The preceding data permit a comparison of the composition of the Pacific deep-sea manganese nodules with that of the underlying sediments. This shows that in general nodules are enriched in Mn, Fe, Co, Ni, Cu, Zn, As, Sb, La, Hf and Th and display

higher Mn/Fe and Ce/La ratios than their associated sediments. The sediments are enriched in Na, Sc, Cr, Br and Ba compared to associated nodules. REE are therefore enriched on average in nodules relative to their associated sediments as noted by Elderfield et al. (1981a). An enrichment sequence tbr elements in nodules relative to their associated sediments in Area K (cf. Glasby et al., 1978; Rankin and Glasby, 1979) has been calculated and shows the different pathways of the various elements in the marine environment (cf. Glasby et al., 1979); the sequence is Co (31) > Sb (17) > Ce ( 1 0 ) > As (6.6) > Th (3.9) > Hf (3.0) > La (2.6) > Fe (2.1) > Ba (1.8) > Sc (0.62) > Na (0.51) > Cr (0.45) > Br (0.22). The element enrichment pattern is similar to that reported by Glasby (1975) and reflects the scavenging power of ferromanganese oxide minerals in manganese nodules for a range of transition and other elements. Fe is the least enriched of the principal transition elements in nodules relative to their associated sediments, reflecting the dominantly lithogenous origin of Fe in pelagic sediments (Glasby et al., 1979). The element enrichment sequence presented here is also in accord with the suggestion of Krishnaswami (1976) that Mn, Co, Ni and Cu in Pacific pelagic clays are

104 principally authigenic in origin whereas Sc, Fe, La and Th are principally detrital in origin. Our data would suggest that elements such as Zn, As and Sb are also principally authigenic and Cr principally detrital in Pacific pelagic sediments. The status of the rare earths and Th cannot be resolved with the data here available. Comparison of the rare earth distributions in the nodules and sediments suggests that there is no systematic relationship between the abundance of the trivalent REE in the nodules and sediments. This is in contrast to the observation of Elderfield et al. (1981a) that the nodules with the highest trivalent REE contents were found in sediments with the lowest trivalent REE contents and vice versa. Nodules with the highest Ce/La ratio are found on sediments with the highest Ce/La ratio as shown in Fig. 3 in agreement with the findings of Elderfield et al. (198 l a), suggesting that the factor controlling the Ce enrichment in the associated nodules and sediments is the same.

/

o// //

K

Ce Lo nods

// //

/

/

/

//

//

/ / //----- slope =~. 39 // //

CO/i/ // //' // /

O P e r u Bosin

G / FO~ /

Ce Lo seds __

I 2

Fig. 3. Plot of the average Ce/La ratios of nodules from each of the sample areas against the corresponding Ce/La ratios of the associated sediments.

Discussion

Several elements, including Sc, Co, As, Hf, Th and REE, are closely associated with iron in Pacific manganese nodules. Similar conclusions regarding the trivalent REE have previously been reached by Elderfield et al. (1981a,b), Moore et al. (1981), Piper and Williamson (1981), Calvert and Piper (1984)and Finney et al. (1984). The reasons for this have been explained in some detail by Glasby and Thijssen (1982a). According to these authors, certain divalent tralasition metal ions (e.g., Ni2÷, Cu 2÷, Zn 2÷) are supplied to nodules from the sediment column in the equatorial Pacific high productivity zone following the dissolution of siliceous tests in situ within the sediment column. These ions are incorporated into the manganese oxide structure and lead to the stabilization of the manganese oxide phase as 10 A manganite. Nodules from the low productivity red clay regions do not have this additional biogenic source of elements and therefore by default contain higher contents of the iron oxyhydroxide phase (Chayes, 1960). Since a number of elements (including the REE) have cations too large to fit into the interlayer structure of the manganese oxide lattice, these elements are preferentially and non-discriminantly incorporated into the iron oxyhydroxide phase. They therefore tend to occur preferentially in nodules with 6-MnO2 rather than i0 A manganite as the principal manganese oxide phase (~-MnO2 has higher contents of Fe) and are derived dominantly from seawater (cf. Glasby, 1973; Piper 1974a;O'Nionset al., 1978, 1979; Addy, 1979; Piepgras et al., 1979; Piepgras and Wasserburg, 1980; Goldstein and O'Nions, 1981), although much of the REE content of seawater occurs in the particulate form (Murphy and Dymond, 1984; de Baar et al., 1983, 1985). Dymond et al. (1984), on the other hand, consider that the bulk of La in equatorial Pacific nodules is supplied by oxic diagenesis. A rather simple hypothesis therefore emerges for the incorporation into manganese nodules of those elements unable to be accommodated in the 10 A manganite phase involving the sorption and incorporation of these elements from seawater into the iron oxyhydroxide phase. This idea is in accord with the observations of Elderfield et al. (1981b) that the upper surfaces of equatorial N. Pacific nodules have higher Fe and REE contents and higher Ce anomalies than the under surfaces (cf. Moore et al., 1981).

105 Elderfield and Greaves (1982), however, suggest that the REE are mobile during early diagenesis. These data also support the tentative conclusion of Glasby (1973) that the rare earth concentration in nodules is inversely proportional to the nodule accretion rate (cf. Glasby and Thijssen, 1982a; Finney et al., 1984). Elderfield et al. (1981a) have suggested that the REE content of nodules is related to both a Fe- and a P-phase and is governed by surface reactions involving these two competing phases (cf. Calvert and Piper, 1984). The P-phase is thought to be fish debris. However, as argued by Glasby and Thijssen (1982a), P in deep-sea nodules is probably dominantly incorporated into the iron oxyhydroxide phase, possibly as an iron phosphate, so that this division appears to be unnecessary, except in certain well-defined cases where fish debris is visible in the nodule (as a shark's tooth, for example; cf. Thijssen et al., 1985). Re-examination of the data of Elderfield et al. (1981a), for instance, shows that Fe and P in the nodules display a correlation coefficient of +0.87, suggesting that these elements are closely associated in the nodules rather than existing as discrete phases. The correlation coefficients of La (+0.92) and Ce (+0.96) with Fe and of La (+0.84) and Ce (+0.90) with P also stress this interrelation. The average Fe/P ratio of these nodules (51.4) indicates that Fe is the dominant component. Fish debris analyzed by Dymond and Eklund (1978) contains 34.4% P2Os and 2400-2500 ppm La. A nodule containing 0.2% P would therefore contain 33 ppm La if this P content was derived solely from this sort of fish debris. This is less than half the amount computed by Elderfield et al. (1981a, fig. 7b) to be required from this source. More importantly, the Ce/La ratio of fish debris measured by Dymond and Eklund (1978) is < 0.05. If fish debris were a major contributor to the REE abundance in the nodules, the Ce/La ratio of the iron oxide phase would have to be extremely high (approximately double the measured value for the whole nodule) to compensate. Finally, Elderfield et al. (1981a) offer no mineralogical or petrographic evidence for the presence of fish debris in the nodules. The data do not therefore appear to support the two phase mechanism for the uptake of REE into deep-sea nodules proposed by Elderfield et al. (1981a). An interesting observation is the mirror-image relationship between the REE patterns of deep-sea manganese nodules and seawater noted by Piper (1947a) and Elderfield et al. (1981a). We believe that

this indicates that manganese nodules are one of the principal sinks for the REE in seawater and that this extraction has taken place at steady state over geological time (cf. Staudigel et al., 1985). This can be shown by approximate mass balance calculation using La as an example. Assuming that there are approximately 1012 tonnes of manganese nodules in the Pacific each containing approximately 80 ppm La, this is equivalent to 80 x 10 6 tonnes of La. The Pacific Ocean, on the other hand, contains approximately 707 x 106kin a of seawater with a La content of approximately 3 × 10 -6 ppm (Brewer, 1975). This is equivalent to 2.1 x 10 6 tonnes of La. For comparison, the computed residence time of La in seawater is about 400-600 years (Piper, 1974a; Brewer, 1975; Elderfield and Greaves, 1982; de Baar et al., 1985). Although these calculations are very rough, they do indicate the importance of manganese nodules as a sink for the REE in seawater. Discussions of the mass balance of REE in seawater have also been given by Piper (1974a,b), Martin et al. (1976), Gurvich and Lisitsyn (1980), Keasler and Loveland (1982), Fleet (1984), Hoyle et al. (1984), Murphy and Dymond (1984), Thomson et al. (1984) and de Baar et al. (1985). It should be noted that, from the data of Ludden and Thompson (1978, 1979) (cf. Elderfield et al., 1981a, Fig. 1), altered marine basalts may contain about 15 ppm La. Assuming that deep-sea nodules contain approximately 20% lithogenous fraction (Glasby and Thijssen, 1982b), about 3 ppm (or up to 5%) of the La in deep-sea manganese nodules could be derived from weathered basaltic material incorporated in the nodule structure. The REE content of manganese nodules is therefore dominantly hydrogenous with possibly a minor lithogenous component. Biogenous material has a REE pattern quite different from that of manganese nodules (cf. Piper, 1974a), suggesting that it does not contribute directly to the REE content of nodules (cf. Elderfield et al., 1981a; Palmer, 1985). The above suggestions all tie in with the idea that the trivalent REE ions (along with a number of other elements) are incorporated into aeep-sea manganese nodules from seawater by adsorption onto the iron oxyhydroxide phase. We reject the assertions of Elderfield et al., (1981a) that "the mechanism of direct precipitation of the REE from seawater is clearly oversimplistic"

106 and that "it is unlikely that the REE are directly precipitated from seawater since seawater is highly undersaturated with respect to likely trivalent REE salts" since sorption reactions on highly reactive surfaces are being considered. We also reject the statement of Elderfield et al., (198 lb) that "Ce appears to be the only REE which is derived predominantly from the overlying seawater". One of the most obvious features of the data is the very high positive Ce anomaly of the nodules from Area K in the S.W. Pacific compared to those of nodules from the equatorial Pacific. The average Ce/La ratio of nodules from Area K, for example, is 8.0 compared to 3.7 for Area C nodules. We believe that this reflects the migration of well-oxygenated Antarctic Bottom Water northwards through the Samoan and Aitutaki Passages. The presence of this relatively fast flowing, well-oxygenated bottom water over the S.W. Pacific nodule field facilitates the oxidation of Ce to the tetravalent state and hence its incorporation into the nodules. This scheme appears to be compatible with the ideas of de Baar et al. (1983, 1985). The presence of the AABW could account for the high Ce/La ratio of Area K nodules and thus adds support to the idea of Glasby (1973) that the Ce/La ratio in nodules is a function of the redox conditions of the environment at the time of deposition (cf. Piper, 1974a; Michard and Renard, 1975; Addy, 1979; Courtois and Clauer, 1980; Brookins, 1983). The removal of the REE (and particularly Ce) by the nodules would lead to the low REE content and Ce depletion of the AABW (cf. Piper, 1974a). For this reason, it would be most interesting to study the REE content of the AABW along its migration path. We believe that the Ce 4÷ ion, like the trivalent REE ions, is incorporated in the iron oxyhydroxide phase of the nodules since, with an ionic radius of 0.94 ,/~ (Glasby, 1973), it is also too large to fit into the manganese oxide lattice. It should be noted that the nodules with the highest cerium anomaly (from Area K) also contain 6-MnO2 as the principal manganese oxide phase. The factors relating the Ce content of the nodules and the nodule mineralogy therefore appear to be different from those proposed by Elderfield et al. (1981a). The higher Ce/La ratio of nodules from Area C (3.7) compared to those from Areas F (1.4) and G (1.5) may also reflect the migration path of the AABW

which passes through the Samoan Passage and Aitutaki Passage and then north of the equator until finally reaching the Peru Basin (van Andel et at., 1975; Lonsdale and Smith, 1980; Nemoto and Kroenke, 1981). The decrease in the Ce/La ratio of the nodules along the path of the AABW from Area K (8.0) through Area C (3.7) to the Peru Basin (2.0) could be explained by this mechanism. If so, it lends strong support to the idea mentioned above that the Ce/La ratio of the nodules is an important redox indicator. Elderfield and Greaves (1981) have recently noted the unusual rare earth abundance pattern of Bauer Deep nodules and in particular the negative cerium anomaly (cf. Murphy and Dymond, 1984; Wang et al., 1984). This is interpreted as being due to the input of hydrothermal iron oxides into the sediments of the Bauer Deep. In fact, the Bauer Deep nodules have an average Ce/La ratio of 1.2 and are intermediate in rare earth abundance between those from Areas F and G studied here which also display negative cerium anomalies and have similar rare earth abundance patterns. The negative cerium anomalies of the Bauer Deep nodules are therefore not unique. The settings of Areas F and G suggest that a hydrothermal component plays no role in the genesis of these deposits. The Bauer Deep nodules therefore appear to be part of a suite of equatorial S. Pacific nodules. The fact that these deposits do not lie on the migration path of the AABW is probably a more important factor in accounting for their rare earth element geochemistry than the proximity to a hydrothermal source. Other authors, however, deduce a hydrothermal REE input into ocean sediments and nodules (Klinkhammer et al., 1983; Michard et al., 1983; Dymond et al., 1984; Murphy and Dymond, 1984), although Dymond et al. (1977) found that the REE distribution in Bauer Deep sediments is associated with a detrital-hydrogenous rather than a hydrothermal factor. The observation of the highest Ce/La ratio of the nodules associated with the highest Ce/La ratio of the underlying sediments suggests that the sediments are influenced by the same processes and that Ce is oxidized to the tetravalent state not only in the nodules but also in the sediments by the same mechanism. The migration path of the AABW may therefore also influence the Ce/La ratio of the sediments. It will be noted that the highest Ce/La ratio of the nodules (in Area K) is associated with the lowest Mn/Fe ratio (cf.

107

E l d e r f i e l d et al., 1 9 8 1 a ; Calvert a n d Piper, 1984). This e m p h a s i z e s t h e f u n d a m e n t a l dissimilarity b e t w e e n the g e o c h e m i s t r i e s o f Ce a n d M n in m a n g a n e s e nodules. Elderfield et al. ( 1 9 8 1 a ) have also n o t e d t h a t c e r i u m is o n e o f t h e small g r o u p o f e l e m e n t s for w h i c h r e m o v a l f r o m s e a w a t e r takes place via h i g h valency states a n d suggested t h a t t h e e n r i c h m e n t o f Ce in m a n g a n e s e n o d u l e s m i g h t o c c u r b y a similar m e c h a n i s m to t h a t o f Co. Whilst we also see the positive c o r r e l a t i o n b e t w e e n Ce a n d Co in t h e n o d u l e s n o t e d by Elderfield et al. ( 1 9 8 1 a ) , a similar positive correl a t i o n is also o b s e r v e d b e t w e e n La a n d Co. T h e analogy b e t w e e n the g e o c h e m i s t r i e s o f Ce a n d Co s h o u l d t h e r e f o r e n o t be t a k e n t o o far (cf. G l a s b y a n d Thijssen, 1982a).

Acknowledgements O n e o f t h e a u t h o r s ( G . P . G . ) w o u l d like t o t h a n k t h e A l e x a n d e r - v o n - H u m b o l d t - S t i f t u n g for s u p p o r t whilst writing this paper. R.G. was s u p p o r t e d b y a g r a n t f r o m the D a n i s h N a t u r a l Science R e s e a r c h Council.

References Addy, S.K., 1979. Rare earth element patterns in manganese nodules and micronodules from northwest Atlantic, Geochim. Cosmochim. Acta, 4 3 : 1 1 0 5 - 1 1 1 5 . Aplin, A.C., 1984. Rare earth element geochemistry of Central Pacific ferromanganese encrustations. Earth Planet. Sci. Lett., 71: 13-22. Arrhenius, G., Bramlette, M.N. and Picciotto, E., 1957. Localization of radioactive and stable nuclides in ocean sediments. Nature (London), 180: 8 5 - 8 6 . 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: J.L. Bischoff and D.Z. Piper (Editors), Marine Geology and Oceanography of Pacific Manganese Nodule Province. Plenum, New York, N.Y., pp. 397-436. Bonatti, E., 1981. Metal deposits in the oceanic lithosphere. In: C. Emiliani (Editor), The Sea, Vol. 7. Wiley, New York, N.Y., pp. 6 3 9 - 6 8 6 . Bonnot-Courtois, C., 1980. Le comportement des terres rares au cours de l'alt~ration sous-marine et ses consequences. Chem. Geol., 30: 119-131. Bonnot-Courtois, C., 1981. Distribution des terres rares darts les d~pots hydrothermaux de la zone FAMOUS et des Galapagos - comparaison avec les s~diments m~tallif~res. Mar. Geol., 39: 1-14.

Brewer, P.G., 1975. Minor elements in seawater. In: J.P. Riley and G. Skirrow (Editors), Chemical Oceanography, Vol. 1. Academic Press, London, pp. 4 1 5 - 4 9 6 . Brookins, D.G., 1983. E h - p H diagrams for the rare earth elements at 25°C and one bar pressure. Geochem. J., 17: 223-229. Bruland, K.W., 1983. Trace elements in sea-water. In: J.P. Riley, and R. Chester (Editors), Chemical Oceanography, Vol. 8. Academic Press, London, 2nd ed., pp. 157-220. Burnett, W.C., Roe, K.K. and Piper, D.Z., 1983. Upwelling and phosphorite formation in the ocean. In: E. Suess and J. Thiede (Editors), Coastal Upwelling and its Sediment Record, Part A: Responses of the Sedimentary Regime to Present Coastal Upwelling. Plenum, New York, N.Y., pp. 377 -397. Calvert, S.E. and Piper, D.Z., 1984. Geochemistry of ferromanganese nodules from DOMES Site A, Northern Equatorial Pacific: Multiple diagenetic metal sources in the deep sea. Geochim. Cosmochim. Acta, 4 8 : 1 9 1 3 - 1 9 2 8 . Chamley, H. and Bonnot-Courtois, C., 1981. Argiles authig~nes et terrig~nes de l'Atlantique et du Pacifique NW (Legs 11 et 58 DSDP): apport des terres rares. Oceanol. Acta, 4: 229-238. Chayes, F., 1960. On correlation between variables of constant sum. J. Geophys. Res., 65: 4185-4193. Courtois, C. and Clauer, N., 1980. Rare earth elements and strontium isotopes of polymetallic nodules from southeastern Pacific Ocean. Sedimentology, 27: 6 8 7 - 6 9 5 . Courtois, C. and Hoffert, M., 1977. Distribution des terres rares dans les s~diments superficiels du Pacifique sud-est. Bull. Soc. G~ol. Fr. (7), 19: 1245-1251. de Baar, H.J.W., Bacon, M.P. and Brewer, P.G., 1983. Rareearth distribution with a positive Ce anomaly in the Western North Atlantic Ocean. Nature (London), 301: 324-327. de Baar, H.J.W., Bacon, M.P., Brewer, P.G. and Bruland, K.W., 1985. Rare earth elements in the Pacific and Atlantic Oceans. Geochim. Cosmochim. Acta, 49: 1943-1959. De Carlo, E.H. and McMurtry, G.M., 1985. Rare earth elements in ferromanganese deposits from the Hawaiian Archipelago and neighbouring seamounts within the Exclusive Economic Zone. EOS (Trans. Am. Geophys. Union), 66(46): 1083 (abstract). Desprairies, A. and Bonnot-Courtois, C., 1980. Relation entre la composition des smectites d'alt~ration sous-marine et leur cortege de terres rares. Earth Planet. Sci. Lett., 48: 124-130. Dymond, J. and Eklund, W., 1978. A microprobe study of metalliferous sediment components. Earth Planet. Sci. Lett., 4 0 : 2 4 3 - 2 5 1 . Dymond, J., Corliss, J.B. and Heath, G.R., i977. History of metalliferous sedimentation in Deep Sea Drilling Site 319, in the South Eastern Pacific. Geochim. Cosmochim. Acta, 41: 741-753. Dymond, J., Lyle, M., Finney, B., Piper, D.Z., Murphy, K., Conard, R. and Pisias, N., 1984. Ferromanganese nodules from MANOP Sites H, S, and R - C o n t r o l of mineralogical and chemical composition by multiple accretionary processes. Geochim. Cosmochim. Acta, 4 8 : 9 3 1 - 9 4 9 .

108 Appendix A Analytical data of manganese nodules Area

C

S t a t i o n No./size class (mm)

Na (%)

K (%)

Sc (ppm)

Cr (ppm)

Fe (%)

Co (ppm)

Zn (ppm)

As (ppm)

Br (ppm)

Sb (ppm)

4 4 4 4 8 19 19 21 23

G B f > 100 GBr80--100 GB ~60--80 GB ~20--40 G B ~20 --40 GB~> 100 GB r60--80 GB ~80--100 GB r 3 0 - 4 0

2.16 2.14 2.32 2.30 2.42 2.28 2.59 2.07 2.19

0.58 0.77 0.84 0.70 1.04 0.85 0.66 0.86 0.86

10.2 10.3 9.8 8.5 9.7 9.5 10.9 11.4 9.2

13 13 11 7 --35 11 --

5.08 4.95 4.83 3.86 4.96 4.96 5.43 4.19 4.42

2050 2240 2120 1930 2150 2030 2330 1630 2830

1200 1030 1150 1330 1630 1240 1340 1210 697

50 54 57 46 65 60 61 48 58

21 22 23 19 30 17 19 12 19

40.7 37.8 41.7 38.9 39.1 43.8 42.8 38.9 36.0

52 52 52 52 52 53 93 93 93 62 70 76 76 78

GB'60--80 GB'40-60 GB r 2 0 - 4 0 GB '15 - 2 0 G B ' < 10 GB ' 2 0 - 4 0 GB ' 2 0 - 4 0 GB '10 - 2 0 GB '5 --10 GB ' 2 0 - - 4 0 GB/5--10 GB/15--20 GB/10-15 GB/80--100

1.77 1.92 2.10 1.99 1.79 2.08 1.95 1.81 1.83 2.50 2.15 0.71 2.00 2.34

0.70 0.61 0.50 0.50 0.54 0.32 0.76 0.88 1.03 0.60 1.04 0.61 0.81 0.82

9.3 9.8 8.4 9.2 9.4 7.7 9.7 11.9 12.3 7.6 12.4 8.7 10.3 8.3

3 13 4 3 11 4 6 12 13 ------

4.98 5.77 4.98 5.65 6.04 4.33 6.37 7.54 7.89 4.71 7.55 5.62 6.31 5.39

851 1040 995 991 1120 855 1160 1130 1180 844 1230 1090 1150 961

1600 1290 1460 1330 1090 1450 1510 1250 1100 1740 1060 1580 1080 1790

34 44 39 42 40 40 50 48 45 45 45 29 47 33

15 6 13 8 8 11 23 15 10 16 28 24 10 27

33.3 36.2 41.1 36.2 29.2 42.1 31.3 26.8 24.2 46.4 25.3 30.9 28.5 35.0

GB/20--40 GB/IO--20 G B / < 10 GB/10--15 G B / < 10 GB/broken nodule

1.69 1.64 1.59 1.71 1.80 1.77 2.01

0.57 0.64 0.53 1.00 1.19 0.82 0.50

8.2 8.4 8.6 4.6 4.6 14.2 7.2

8 7 2 52 62 111 17

9.26 9.40 9.84 11.0 11.6 11.3 8.08

968 1010 1090 867 885 982 850

1570 1410 1460 931 789 740 1540

71 77 83 65 76 79 69

11 15 21 6 -12 22

27.9 26.4 27.4 17.1 17.1 17.8 31.9

108 G B / b r o k e n n o d u l e

1.84

0.72

7.8

8.70

989

1590

80

19

30.0

137 D K / 3 0 137 D K / 2 0 137 D K / b r o k e n n o d u l e

1.89 1.79 1.59

0.89 0.59 0.28

8.7 9.6 12.5

12 4 13

8.86 9.64 18.0

771 1110 1460

1360 1520 720

79 96 129

20 20 5

25.4 28.5 26.9

K

155 155 155 165 193 193 193 193 193 226 226 226 226 226 191 196

GB/40-60 GB/20--30 GBtl0--20 GB~60--80 G B ~40 --60 GB r 3 0 - 4 0 GBf20--30 GBq5--20 G B t < 10 GB~> 100 GB ~40--60 GB ~30--40 GB ~20--30 GB~< 20 G B ' < 20 GB ' 2 0 - 4 0

1.59 1.49 1.49 1.88 1.74 1.73 1.76 1.66 1.47 1.85 1.55 1.52 1.62 1.59 1.38 1.07

0.95 0.72 0.66 0.66 0.56 0.49 0.48 0.71 0.66 0.84 0.52 0.51 0.45 0.44 0.60 0.44

14.7 15.7 15.2 13.0 14.4 12.5 15.0 13.9 16.0 13.5 14.3 13.6 13.6 11.7 9.8 12.6

64 50 53 34 82 96 118 90 73 ----32

17.0 19.7 18.8 16.8 17.9 16.8 17.3 18.2 15.5 13.4 14.7 16.3 15.7 14.2 12.0 17.3

2930 3560 3530 4750 4260 4140 4060 4010 3400 3730 4150 4810 4750 4440 3700 6970

214 474 226 -162 498 242 -174 240 208 259 400 405 485 -

105 144 147 146 154 151 156 158 136 125 145 147 144 133 105 127

8 8 9 31 25 24 25 25 13 12 19 13 19 17 23 11

24.8 32.6 33.4 25.5 30.0 22.8 29.4 33.0 28.2 25.1 25.8 28.2 26.9 26.0 23.2 24.3

Peru Basin

31 G B / 6 0 - - 8 0 31 G B / 2 0 - - 4 0 573 G B / 4 0 - - 8 0

2.05 2.43 2.29

0.59 0.69 0.55

8.5 8.1 7.9

9 18 3

560 870 798

1090 1240 1510

58 60 72

33 36 28

39.8 37.4 38.3

G

120 120 120 146 146 146 99

GB/20-3O

4.77 5.31 6.52

109

Ba (ppm)

La (ppm)

2170 2360 2450 2360 1170 1820 2890 2080 2400

99 99 99 75 95 97 107 88 81

2500 1650 1220 1070 1160 1250 912 774 981 1520 1090 1200 1180 2480 1780 1870

Nd (ppm)

Sm (ppm)

380 378 352 218 246 395 434 408 283

157 133 123 75 112 174 176 150 109

31.4 31.5 30.0 21.7 33.5 40.3 41.6 38.7 31.1

62 67 61 56 60 57 65 62 67 63 66 47 66 60

71 94 110 69 83 80 85 94 105 79 63 97 103 72

-79 64 64 -50 75 72 72 -55 38 80 19

770 866 855 1620

96 100 106 88 87 88 70

128 129 142 121 122 115 104

1810

85

1780 1580 1490

467 744 652 370

--

--

542 582 827 ---

482 872 399 --

--

-4010 3390 2380

Ce (ppm)

Eu (ppm)

Tb (ppm)

Yb (ppm)

Lu (ppm)

8.5 8.7 8.8 5.8 7.3 8.3 9.5 7.8 5.3

3.3 4.4 3.4 2.6 4.0 4.2 4.5 4.0 5.6

14.2 13.0 14.4 9.7 11.3 13.7 15.9 14.1 10.2

2.0 1.9 2.1 1.4 1.6 2.0 2.2 2.0 1.0

12.6 15.2 14.2 13.5 12.3 13.6 18.3 13.5 17.8 18.5 18.7 13.5 18.1 15.7

3.9 4.7 4.3 3.8 3.7 4.0 4.7 4.2 4.1 3.1 3.5 4.2 4.1 3.5

2.3 2.6 3.0 2.6 2.2 2.2 2.1 2.6 2.3 2.4 2.1 2.2 2.5 1.9

8.7 10.3 9.2 8.7 8.0 8.8 10.7 9.3 9.3 9.3 9.4 8.9 9.9 8.9

84 103 79 64 58 69 72

15.4 15.5 16.0 19.5 13.8 13.8 16.3

4.8 4.7 4.9 4.8 4.2 4.3 4.0

2.9 2.7 3.0 2.9 2.4 2.4 2.3

131

77

18.3

4.1

79 115 182

98 154 419

77 110 166

17.3 24.0 42.5

129 174 178 180 186 186 189 181 143 163 178 182 174 161 146 153

948 1360 1260 1630 1690 1660 1330 1480 1180 1350 1300 1480 1480 1160 1000 1470

156 218 189 244 179 218 188 236 121 115 156 193 ---148

63 60 71

127 144 t74

54 61 62

Hf (ppm)

W (ppm)

Th (ppm)

Area

4 6 3 4 5 5 6 5 4

56 60 64 48 47 69 67 61 64

31 29 29 17 20 28 35 30 24

C

1.4 2.0 1.6 1.4 1.2 1,3 1.8 1.4 1.3 1.3 1.3 1.4 1.4 1.3

2 4 3 3 4 2 4 5 5 5 3 3 5 2

44 42 39 41 46 38 42 37 34 47 45 55 53 58

4 7 6 6 4 4 6 4 6 1 1 5 5 3

12.9 13.0 13.8 11.4 10.9 11.3 10.3

2.0 2.0 2.2 1.8 1.7 1.7 1.5

5 6 6 6 6 7 4

43 53 52 35 33 37 51

3 3

2.3

10.8

1.7

5

3.8 5.6 8.5

2.2 3.7 5.5

10.9 15.6 21.7

1.6 2.4 3.3

36.8 36.3 34.2 39.6 36.4 33.0 36.8 38.2 27.6 38.6 35.8 46.7 38.9 34.4 22.6 26.1

8.4 9.3 9.0 10.2 10.0 9.7 8.7 9.2 6.7 8.9 9.4 9.8 9.0 8.2 6.9 8.1

5.9 3.8 5.1 3.7 3.7 5.1 4.2 5.9 3.1 3.5 6.2 4.0 4.1 4.0 4.3 5.0

16.4 18.5 17.4 17.7 23.1 16.1 17.3 18.7 13.1 17.3 18.8 20,1 16.4 18.6 16.0 18.9

9.9 14.2 17.6

3.4 3.4 4.1

2.1 1.6 2.3

9.7 8.3 11.1

S t a t i o n No./size class (ram) 4 4 4 4 8 19 19 21 23

G B / ~ 100 GB/80-100 GB/60-80 GB/20-40 GB/20--40 G B / ~ 100 GB/60-80 GB/80-100 GB/30-40

52 52 52 52 52 53 93 93 93 62 70 76 76 78

GB ' 6 0 - 8 0 GB ' 4 0 - 6 0 GB'20-40 GB ' 1 5 - 2 0 GB ' ~ 10 GB r 2 0 - 4 0 GB'20-40 GB¢IO-20 GB ~5- 1 0 GB ~ 2 0 - 4 0 GB ' 5 - 1 0 GBPI5-20 GBrlO-15 GB'80-100

3 3 3 3

120 120 120 146 146 146 99

61

3

108

5 7 --

54 54 35

3 3 9

137 137 137

GB/20-40 GB/IO-20 G B / ~ 10 GB/20-30 GB/IO-I 5 G B / ~ 10 GB/broken nodule GB/broken nodule DK/30 DK/20 DK/broken nodule

2.3 3.4 2.7 3.0 3.7 2.2 2.6 2.4 1.6 3.1 2.4 3.1 3.1 2.7 2.5 2.7

15 21 21 14 16 16 17 19 18 13 14 14 13 13 8 19

19 28 25 42 31 34 38 31 17 40 44 53 62 60 52 31

44 53 52 71 73 63 73 67 55 46 47 45 47 37 37 59

K

155 155 155 165 173 193 193 193 193 226 226 226 226 226 191 196

1.5 1.2 1.8

5 5 5

76 67 54

8 12 10

Peru Basin

31 G B / 6 0 - - 8 0 31 G B / 2 0 - - 4 0 573 G B / 4 0 - 8 0

F

G

4

GB ' 4 0 - - 6 0 GB ~ 2 0 - 3 0 GB ~ 1 0 - 2 0 GB ' 6 0 - - 8 0 GB ~ 4 0 - 6 0 GB ~ 3 0 - 4 0 GB'20-30 GB f 1 5 - 2 0 G B ~ 10 G B ' > 100 GBf40-60 GB~30-40 GB t 2 0 - 3 0 G B t ' ( 20 GBf(20 GB t 2 0 - - 4 0

110 Appendix Area

A

(Continued)

Station No./depth (cm) 574 39 46 46 54

Na (%)

Ca (%)

Sc (ppm)

Cr (ppm)

Fe (%)

Co (ppm)

As (ppm)

Br (ppm)

Rb (ppm)

Sr (ppm)

Sb (ppm)

Cs (ppm)

5

5.93 4.59 5.18 4.48 2.57

694 543 643 420 216

1680 1610 1440 1930 1780

71 55 56 70 39

32 16 32 33 26

42.4 44.2 36.4 45.3 53.9

6

3.71 2.05

282 170

1600 1460

45 38

31 35

39.3 60.3

GB/40-60 GB/20--40 GB/20--40 GB/40--60 GB/broken nodule

2.30 2.20 2.35 2.60 3.07

0.61 0.69 0.53 0.54 0.48

7.8 7.1 7.3 6.3 4.7

-

54 G B / 4 0 - 6 0 66 GB/broken nodule

2.84 3.25

0.39 0.59

6.5 4.7

-

71 G B / b r o k e n n o d u l e

2.39

0.76

5.3

4

3.62

317

1670

48

12

38.5

61 G B / b r o k e n n o d u l e

2.16

0.59

6.2

6

4.02

322

1820

42

25

40.2

Co (ppm)

As (ppm)

Br (ppm)

- = not detected or not analysed.

Appendix B Analytical data of sediments Area

Station No./depth (cm)

Na (%)

Ca (%)

Sc (ppm)

Cr (ppm)

Fe (%)

Rb (ppm)

Sr (ppm)

Sb (ppm)

Cs (ppm)

129 120 130

18 78 74

561 ---

2.3 1.2 0.9

3 6 6

49

6

1290

--

0

C

10 K G / 1 0 - - 2 0 26 KG 27 KAL

4.24 3,25 3.31

1.2 0.4 0.5

26.3 22.3 23.8

36 53 58

4.23 3.55 3.79

93 21 23

7.4 2.9 --

D

34 KG

1.32

38.4

3.2

5

0.37

12

--

F

51 K G / t o p 96 KG/top

4.39 3,57

8.7 1.2

15.5 13.6

16 16

2.53 2.22

92 80

8 7

144 116

---

583 404

1.7 0.7

--

124 KG 149 KG

1.72 4,89

30.4 2.8

4.2 17.6

8

1.67 8.66

40 152

8 32

61 128

---

1130 --

0.8 4.3

--

42

162 184 184 206 206 236 236

KG KG/top KG/bottom KG/top KG/bottom KG/top KG/bottom

3.25 3.99 3.31 1.80 2.09 3,82 3.70

3.3 2.4 3.0 9.2 5.6 3.0 1.2

21.1 22.0 21.3 22.5 27.1 23.8 18.8

86 74 108 383 387 45 62

7.33 6.72 6.78 9.90 11.6 6.49 5.95

188

30 19 19 22 15 14 18

87 111 62 44 34 121 76

87 47 39 8 -47 79

--

2.0

2

149 143 68 82 165 112

-170 709 701 --

1.2 2.6 1.1 1.0 1.0 1.3

3 2 --2 7

574 KG/top 574 KG/bottom

3.22 4.50

11.5 3.6

16.3 24.4

32 41

2.56 3.76

52 55

4 6

141 209

141 55

484 324

1.6 1.3

4 5

G K

Peru Basin

--

- = n o t d e t e c t e d or n o t a n a l y s e d .

E l d e r f i e l d , H. a n d G r e a v e s , M . J . , 1 9 8 1 . N e g a t i v e c e r i u m a n o m a l i e s in t h e r a r e e a r t h e l e m e n t p a t t e r n s o f o c e a n i c f e r r o m a n g a n e s e n o d u l e s . E a r t h P l a n e t . Sci. L e t t . , 5 5 : 163-170. E l d e r f i e l d , H. a n d G r e a v e s , M . J . , 1 9 8 2 . T h e r a r e e a r t h elem e n t s in s e a w a t e r . N a t u r e ( L o n d o n ) , 2 9 6 : 2 1 4 - 2 1 9 . E l d e r f i e t d , H., H a w k e s w o r t h , C . J . , G r e a v e s , M.J. a n d C a l v e r t , S.E., 1 9 8 1 a . R a r e e a r t h e l e m e n t g e o c h e m i s t r y o f o c e a n i c ferromanganese nodules and associated sediments. Geoc h i m . C o s m o c h i m . A c t a , 45 : 5 1 3 - 5 2 8 . E l d e r f i e l d , H., H a w k e s w o r t h , C . J . , G r e a v e s , M.J. a n d C a l v e r t , S.E., 1 9 8 1 b . R a r e e a r t h e l e m e n t z o n a t i o n in P a c i f i c ferromanganese nodules. Geochim. Cosmochim. Acta, 45:1231 1234.

F i n n e y , B., H e a t h , G . R . a n d L y l e , M., 1 9 8 4 . G r o w t h r a t e s o f m a n g a n e s e - r i c h n o d u l e s a t M A N O P Site H ( E a s t e r n N o r t h Pacific). G e o c h i m . C o s m o c h i m . A c t a , 4 8 : 9 1 1 - 9 1 9 . Fleet, A.J., 1983. Hydrothermal and hydrogenous ferromanganese deposits: Do they form a continuum? The rare e a r t h e l e m e n t e v i d e n c e . In: P.A. R o n a , K. B o s t r 6 m , L. L a u b r i e r a n d K . L . S m i t h ( E d i t o r s ) , H y d r o t h e r m a l Processes at Seafloor Spreading Centers. Plenum, New York, N.Y., pp. 535-555. Fleet, A.J., 1984. Aqueous and sedimentary geochemistry of t h e r a r e e a r t h e l e m e n t s . I n : P. H e n d e r s o n ( E d i t o r ) , R a r e E a r t h E l e m e n t G e o c h e m i s t r y . Elsevier. A m s t e r d a m , p p . 343-373. F l e e t , A . J . , H e n d e r s o n , P. a n d K e m p e , D . R . C . , 1 9 7 6 . R a r e

111

Ba (ppm)

La (ppm)

Ce (ppm)

Nd (ppm)

2150 3330 2910 2730 2150

73 57 63 58 36

154 124 126 99 72

54 33 50 51 38

12.8 13.3 14.7 14.4 8.2

2950 2680

47 31

95 49

48 32

3170

47

83

48

99

-

Ba (ppm)

La (ppm)

16100 3830 4500

119 43 44

Ce (ppm) 58 82 86

Sm (ppm)

Eu (ppm)

Tb (ppm)

Yb (ppm)

Lu (ppm)

Hf (ppm)

W (ppm)

Th (ppm)

Area

Station No./size class (mm)

4.0 3.2 2.8 3.2 2.1

2.6 1.3 1.9 2.0 2.0

11.6 8.8 9.6 10.4 6.0

1.9 1.4 1.5 1.7 0.9

5 5 6 5 2

60 65 67 60 59

9 8 9 6 4

574 39 46 46 46

12.5 7.7

2.8 1.7

1.9 -

7.9 5.5

1.3 0.9

3 1

47 47

6 4

54 66

40

12.2

2.8

1.6

7.9

1.3

4

63

7

71

33

10.7

2.5

1.7

8.0

1.3

4

47

6

61

GB/40--60 GB/20--40 GB/20-40 GB/40-60 GB/broken nodule GB/40-60 GB/broken nodule GB/broken nodule GB/broken nodule

Nd (ppm)

Sm (ppm)

Eu (ppm)

Tb (ppm)

Yb (ppm)

Lu (ppm)

Hf (ppm)

Th (ppm)

Area

Station No./depth (cm)

123 39 45

28.3 11.5 12.9

7.4 2.8 3.2

5.0 1.5 1.9

14.9 5.2 6.8

2.4 0.9 1.2

4 4 4

7 11 12

C

10 K G / 1 0 - 2 0 26 KG 27 KAL

1030

11

8

7

3.5

0.7

0.4

1.5

0.2

0

1

D

34 KG

4220 3570

73 68

44 40

73 72

20.2 18.7

4.7 4.4

3.2 3.4

12.0 11.9

2.0 1.8

2 2

4 3

F

51 KG/top 96 KG/top

2010 4770

27 113

18 74

24 98

6.6 29.5

1.5 6.0

1.1 4.2

3.9 14.8

0.7 2.6

1 4

1 3

G

124 KG 149 KG

304 429 262 366 438 170 408

99 70 79 67 76 26 44

227 145 142 128 155 81 101

105 88 86 55 66 36 47

23.6 18.5 24.1 14.0 20.6 7.1 12.1

5.9 4.4 4.6 3.5 4.1 1.7 2.5

3.4 2.9 2.9 1.8 1.7 0.8 1.8

11.5 9.3 9.7 4.2 4.8 3.5 5.5

1.7 1.4 1.5 1.0 0.8 0.5 0.9

5 4 5 7 9 3 3

21 15 12 10 11 8 13

K

162 184 184 206 206 236 236

7500 11600

31 43

33 46

32 34

7.0 9.2

1.6 2.4

1.1 1.6

4.8 6.5

0.9 1.2

2 3

5 7

Peru Basin

574 KG/top 574 K G / b o t t o m

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KG KG/top KG/bottom KG/top KG/bottom KG/top KG/bottom

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