232 A. Y. GLIKSON

expansion have, in the main, commenced only since about 1.0 aeons ago.

Acknowledgements I thank W. B. Dallwitz, G. M. Derrick, J. Ferguson, R. D.

Shaw, A. J. Stewart, M. R. Walter and D. Wyborn for their comments on the paper on which this summary is based, and C. Giles for his comments on this summary. Grateful acknowledgement is due to R. W. Page for his permission to incorporate unpublished data on Figure 1.

References ANHAEUSSER, C. R., 1973--The evolution ofthe Early Precambrian

crust of Southern Africa . Philosophical Transactions of the Royal Society of London. A273, 359·88.

ARTH, J. G. , & HANSON, G . N .. 1975--Geochemistry and origin of the Early Precambrian crust of northeastern Minnesota. Geo· chimica et Cosmochimica Acta. 39,325·62.

BAKER, B. H., MOHR, R , & WILLIAMS. L. A. J., 1972-Geology of the eastern rift system of Africa. Geological Society of America Special Paper, 136.

CAREY, ·S. W., 1976-The expanding Earth-an essay review. Earth·Science Reviews. 11,105·43.

DEARNLEY, R, 1966-0rogenic fold belts and a hypothesis of Earth evolution; in AHRENS. L. , PRESS, F., RUNCORN. S. K., & UREY. H. c.. Editors , PHYSICS AND CHEMISTRY OF THE EARTH. Pergamon Press. Oxford. vm, 1·114.

DIMROTH, E. , BARAGAR, W. R. A., BERGERON, R, & JACKSON. G. D ., 1970--The filling of the circum·Ungava geosyncline. Geological Survey of Canada Special Paper. 70-74,45-142.

ENGEL, A. E . J., 1968-The Barberton Mountain Land : clues to the differentiation of the Earth. Geological Society of South Africa Transactions, 71 , 255-70.

ENGEL, A. E. J., SONYA, P., ENGEL, C. G., STICKNEY, D. M., & GRAY, E. J., 1974--Crustal evolution and global tectonics: a petrogenetic view. Geological Society of America Bulletin . 85, 843-58.

GLIKSON, A. Y., 1970--Geosynclinal evolution and geochemical affinities of Early Precambrian systems. Tectonophysics. 9,397-433.

GLIKSON, A. Y., 1972-Early Precambrian evidence of a primitive ocean crust and island nuclei of sodic granite. Geological Society of America Bulletin. 83,3323-44.

GLIKSON, A. Y., 1976a-Earliest Archaean ultramafic-mafic vol•canic rocks: ancient oceanic crust or relic terrestrial maria? Geology. 4,202-5.

GLIKSON, A. Y. , 1976b--Archaean to early Proterozoic shield ele•ments: relevance of plate tectonics. Geological Association of Canada Special Paper. 14,489-516.

GUKSON, A. Y., in preparation-Precambrian sima-sial distribu•tion patterns: evidence of Earth expansion.

GLIKSON, A. Y., & LAMBERT, I. B. , 1976-Vertical zonation and petrogenesis of the Early Precambrian crust in Western Aus•tralia. Tectonophysics. 30,55-89.

GLIKSON, A. Y., DERRICK, G. M., WILSON, I. H., & HILL, R. M., 1976-Tectonic evolution and crustal setting of the middle Proterozoic Leichhardt River fault trough, Mount Isa region, north-western Queensland. BMR Journal of Australian Geology and Geophysics. 1,115-29.

GREEN, D. H., 1972-Archaean greenstone belts may include equi•valen ts of terrestrial maria? Earth and Planetary Science Letters. 15,263-70.

GREENWOOD, W . R. , HADLEY, D. G., ANDERSON, R. E., FLECK, R J. , & SCHMIDT. D. L. , 1976-Late Proterozoic cratonization in southwestern Saudi Arabia. Philosophical Transactions of the Royal Society of London. A2SO, 517-27.

HOFFMAN, P. F., 1973--Evolution of an early Proterozoic con•tinental margin: the Coronation geosyncline and associated aulacogens of the northwestern Canadian Shield. Philosophical Transactions of the Royal Society of London , A273, 547-61.

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BMR Journal of Australian Geology & Geophysics. 2 (1977) 232-233

Chemistry of manganese nodules from the Cape Leeuwin field off Western Australia

L. A. Frakes!, N. F. Exon, and J. W. Granath 2

A preliminary report on the manganese nodule field southwest of Western Australia published in this Journal recently (Frakes, Exon & Granath, 1977) quoted chemical analyses which were carried out on air-dried material. Significantly higher metal values have been recorded in some later analyses done on nodules dried at 105°C.

Tests have shown that the ground, air-dried material retains considerable moisture, which accounts for the higher metal values of the later analyses. The average water

1. Department of Earth Sciences, Monash University, Melbourne. 2. Department of Earth Sciences, Monash University, and State

University of New York, Stony Brook.

content (after drying at 105°C) has been determined at 16 percent.

The relevant chemical data now available on this material are summarised in the accompanying table: in this table metal values (by atomic absorption spectrophoto•metry) have been recalculated assuming a moisture content of 16 percent. Correspondence between the analytical results from different laboratories using different methods is good; Cu values determined by X-ray fluorescence appear to be consistently slightly lower than the AAS results, whereas Ni, Fe and Mn values by XRF are slightly higher than the AAS figures from the other two labora•tories. The analyses were not carried out on the same nodules and, except in the case of Station 9, the spread of

values is less than might be expected from natural dif•ferences in composition between individual nodules in a single dredge haul.

The overall average value of Ni + Cu + Co from all 8 stations taken from the analyses given here is 1.53 percent, compared with the figure of 1.18 percent quoted in the preliminary account.

Station Position Laboratory

Fe

2 40°03'5 6.5 114°IO'E

3 41°53'S 1 11.2 113°57'E 3 13.3

4 37°57'S 1 12.1 103°09'E 2 NO

3 13.08

5 37°OO' S 1 11.0 102°55'E 2 NO

3 11.75

6 36°OO'S 1 11.7 102°oo'E 2 NO

3 12.59

7 35°54'S 1 12.3 99°03' E 2 NO

3 13.36

8 34°58'S 1 10.4 98°58' E 2 NO

3 11.47

9 34°38'S 1 14.2 101°oo' E 2 NO

3 15.32

ND-not determined.

CHEMISTRY OF MANGANESE NODULES 233

Acknowledgement We thank H. A. Jones for his assistance during this

reassessment.

Metal content-weight percent, dry basis

Mn Ni Cu Co Ni+ Cu +Co (Average)

19.3 1.12 .57 .065 1.76

24.0 1.05 .SO .077 1.55 25.14 1.04 .36 NO

21.7 .90 .40 .13 NO .95 .38 .14

24.86 1.00 .34 NO 1.46

23.9 .% .49 .15 NO 1.00 .45 .15 1.60

25.17 1.05 .39 NO

21.5 .84 .42 .15 NO .88 .38 .20 1.44

24.08 .93 .35 NO

22.0 .88 .37 .18 NO .92 .38 .19 1.47

24.01 .98 .33 NO

23.5 1.00 .49 .19 NO 1.00 .43 .20 1.65

25.01 1.05 .40 NO

19.1 .61 .26 .18 NO .90 .38 .23 1.27

22.38 .75 .28 NO

1. Australian Mineral Development Laboratories, Adelaide. Average of two analyses from each station, exceptstation 2 (1 analysIs). Analyses by atomIc ab80rbtIon spectrophotometry.

2. Bureau of Mineral Resources, Canbeua. Analyses by atomic ab80rbtIon spectrophotometry. 3. Monash University, Oayton, Victoria. 5-8 analyses from Stations 4-9; 1 analysis from StatIon 3.

Analyses by X-ray Ouorescence. (Data from Frakes & O'Brien, in press; and O'Brien, unpuhl. data).

References

FRAKES, L.A., EXON. N. F., & GRANATH , J. W., 1977-Preliminary studies on the Cape Leeuwin manganese nodule field off Western Australia. BMR Journal of Australian Geology & Geophysics, 2, 66-9.

FRAKES, L. A. & O'BRIEN, G. , in press-Nickel·rich manganese nodules from the SOutheast Indian Ocean; in VARENTSOV, I. (Editor), INTERNATIONAL MONOGRAPH ON THE GEOLOGY AND GEO•CHEMISTRY OF MANGANESE. Hungarian Academy of Sciences, Budapest.