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Marine manganese deposits. Elsevier oceanography series 15
303 materials (rock, soil, water, etc.) to finding clues to deposits of valuable minerals that are either not exposed or not readily recognizable at the earth's surface. Most of the papers present the results either of original field work or of new analytical techniques. Data from field studies made in Australia appear most frequently (13 papers), followed by the United States (6 papers), Canada (3 papers) and other countries of the world (6 p~]pers). Uranium exploration is the commonest topic (5 papers), followed by exploration for volcanogenic sulfides (4 papers), nickel-bearing serpentinites (4 papers), primary dispersion (4 papers), application of isotope ratios to exploration (3 papers), and exploration case histories (3 papers), A few of the papers presented at the symposium are of considerably more than local or specialized interest. Antweiler and Campbell (p. 17) report that the silver and copper content of alluvial gold serves as a kind of 'signature' indicating the type of deposit from which the gold was derived, Watterson et al. (p. 31) present data to show that tellurium in rocks and their weathering products is an extremely powerful 'pathfinder' element for sulfide deposits. Gulson (p. 85) found that lead-isotope ratios can be used in distinguishing otherwise-identical black shales. Wenrich-Verbeek (p. 337) has optimized a system for collecting and processing samples of water and stream sediment in the course of uranium exploration. Cowart and Osmond (p. 365) report that the ratios of 2 3 4 U t o 2 3 8 U c o n s t i t u t e a u s e ful guide to sandstone-type uranium deposits. Cadigan and Felmlee (p. 381) have studied the precipitation of radium and uranium from spring water and its significance in exploration for deeply buried uranium deposits. Gatehouse et al. (p. 483) have worked out a relatively simple system of sequential extraction of base metals from soil samples forthepurpose of distinguishing metal originating from oxidizing sulfides from that derived from the weathering of normal silicates, In summary, this volume contains an enormous amount of information on modern techniques of mineral exploration, Although some of the material presented is specialized or perhaps of only local
interest, a great deal of it represents new and original contributions to the art of mineral exploration that are of general interest and significance. H.E. Hawkes, Orleans, Vermont
OCEANOGRAPHY G.P. Glasby (Editor), 1977. Marine Manganese Deposits. Elsevier Oceanography Series 15. Elsevier, Amsterdam, 523 pp., Dfl. 127.00, U.S. $ 49.00. This is a timely publication in the field of manganese nodule research. Within the next decade nodule deposits from the central Pacific will be commercially exploited -a possibility first suggested over a hundred years ago. First discovered by HMS Challenger, the ferromanganese concretions called manganese nodules have since been found to occur in most of the world's oceans and in many lakes and estuaries. Given the variety of environments in which nodules form it has not yet been possible to identify a unique source for the metals involved -- or a unique mode of formation. The value of this book is in the presentation by its authors of clear reviews of the nature of nodules in the various environments, and the application of the various theories of formation to these settings. It is clear, however, that this is a consolidation of information, rather than a unique set of solutions to the questions about nodules and their growth. It is most interesting that the basic hypotheses of Murray and Renard (1891) and G~mbel (1878) are remarkably current. The slow-growing cryptocrystalline material of the nodules is difficult to work with, and because of the very slow rates of growth involved, even more difficult to model successfully. Environments of growth show a wide variety of physical and chemical parameters, and include: shallow and deep oceanic areas; fresh and salt water, presence or absence of local volcanism; variations in substrate type; and variations in the biogenic contribution to the sediment locally. Thus, a single process cannot be expected to be operative in all cases. Perhaps the single largest failing
304 of the Glasby collection of papers is that the question of environment is treated only in a generalized view, and the reader is left with no insight as to the fine scale of variation in sea-floor environments and in nodule facies, The editor provides in the introductory chapter an historical perspective of the discovery and early investigations of manganese nodules. The reproduction of the Challenger Report figures and the discussion of the early hypotheses for the formation of the nodules are particularly intriguing when contrasted with the modern results on morphology and formation as discussed in Chapters 5 and 10. The distribution of nodules in the oceanic environment is reviewed by D. Cronan. Oceanic in this sense connotes both the basin floor and local and regional volcanic features -- islands and sea mounts, ridges, and oceanic plateaus. For the perspective view this is an excellent chapter; however, for the details of the variations which Cronan discusses the scale of charts are too general and more recent work has refined the boundaries (and mixtures) of the various facies (e.g., Meylan et al., 1975). It would have been quite useful to follow this discussion with a picture of the local facies distribution within such regional nodule deposits, The author's note added in proof (p. 44) points up this problem. Shallow water marine and lacustrine nodules are discussed by Clavert and Price. Lacustrine nodules are quite different from oceanic nodules, in chemistry, substrate relationships, and presumably in growth mechanisms. These nodule types derive their components clearly from the substrate through diagenetic reactions. Their rate of formation is several orders of magnitude more rapid than that of oceanic nodules, Only the very small concretions (pea ores) of this environment morphologically resemble oceanic nodules. These authors also provide a useful discussion of the views on biological activity in the formation of ferromanganese oxides, Fossil nodules have received relatively little attention in the past fifty years. H. Jenkins provides a concise review of this subject. Fossil nodules are known from oceanic, marginal, and littoral environments, and in general are quite similar to their modern-day
counterparts. The littoral forms are of interest as the high manganese/iron ratios reported in modern nodules in this environment have been taken to be a result of diagenetic mobilization in the substrate - a factor which would seem to work against the preservation of fossil nodules. Fossil nodules of the oceanic variety are preserved in obducted sections of oceanic plates, or on structures being uplifted by plate collision or subduction such as the Barbados section. The chapter on morphology by Raab and Meylan discussed the variability and identity of nodule facies. Murray and Renard (1891) reported that a Challenger sample site could be identified from the morphology of the nodules after a brief study of their forms. Unfortunately this chapter concentrates on central Pacific nodules, to the exclusion of facies of great variety in other areas. It would have been most useful if the goals of the first portion o f the chapter had been continued throughout. Internal structure of Pacific nodules is very thoroughly presented by R. Sorem. In addition to providing a well-illustrated guide to the investigation of nodule structures, he presents the relationship between these structures and the theories of growth and formation of the nodules. The chapter on mineralogy is perhaps the most interesting of the book, as it arranges a uniform nomenclature from the mass of manganese oxide mineralogies for application to manganese nodules. Burns and Burns prefer the terms todorokites, birnessite, and $-MnO 2 for the principal minerals in nodules, and demonstrates through crystal chemical considerations how these and related Fe oxyhydroxides may interrelate in the seeding and trace metal enrichment of nodules. Much of this discussion is drawn by inference, as for instance, the crystal structure of todorokite has not yet been determined due to the difficulty in finding single crystals for structural analysis. It is clear also that the strictly controlled crystal chemical relationships are unable to distinguish disturbing events which might have masked their existence subsequent to the growth phases. T.L. Ku reviews the radiometric techniques which have been applied to the dating
305 of nodules and the determination of growth rates, and confirms once again the generally slow rate of accretion for nodules lacking obvious diagenetic or volcanic associations, Episodic nodule growth cannot be discounted entirely, but the data from a number of different dating approaches suggests that such rapid growth intervals are notthe norm, and that they are not necessary in order to maintain the nodules at the sea floor, The formation of manganese and iron in marine sediments and the mechanisms of removal of these and trace metals from sea water are presented in chapters by Elderfield, and by Murray and Brewer. The relative roles of litho,jenous and hydrogenous routs support the crystal models of Burns and Burns. Murray points out that the ages reported for the surfaces of buried nodules are the same as the enclosing sediment which implies metal accretion from sea water or at the sediment/water interface. He favors adsorption as the controlling enrichment mechanism, which makes it unnecessary to involve organic or organo-metal complexes for enrichment. This does not, however, explain the pattern of enriched nodules related to zones of high organic productivity (i.e., the north equatorial Pacific nodule belt), and so leaves open to question a critical step in the enrichment process. From consideration of adsorption processes, Mn should remove more Co than Fe phases, although again this is not always clear in nodule populations. Nodule processing techniques of the industrial groups are proprietary, but various hydrometallurgical techniques have been discussed in general form. Fuerstenau and Han review the known techniques and behavior of the metal species in each. Techniques such as acid leaching, ammonia leaching, chlorination, and smelting all provide different extraction efficiencies for the various metals. The various techniques also present different environmentconsiderations at the plant site. Choices of method will depend on extraction efficiencies for the metals sought (typically Co, Cu and Ni, but possibly including Mn and Mo) and environmental considerations. Amos et al. report on the environmental
effects of mining in the deep ocean. A problem here is that the mid-ocean environment - pelagic and benthic - has not previously been studied at the level of detail necessary to provide the baseline against which environmental impacts can be observed. Such detailed studies are now being carried out in the N O A A DOMES project (Deep Ocean Mining Environmental Studies). The first successful pilot mining tests have also just taken place (OMI aboard the Sedco 445) so that reports on the actual impact will appear shortly. The chapters on economic aspects of nodules, environmental aspects of mining, and legal regimes discuss areas which are rapidly changing with current political and scientific efforts. As this review is being written, the first deep ocean (5,000 m) tests of a hydraulic mining system has been successfully completed, with approximately 1000 tons of nodules mined over a 4 - 5 day interval. Further, the success or failure of the seventh session of the United Nations Law of the Sea conference will shortly provide either the necessary legal regime for licensing and operation of deep ocean mines, or the incentive for national legislation and mini-treaties to accomplish the same end. With this step the technology and legal regimes will be available for the development of the resource.
References G6mbel, W., 1878. Uber die im stillen Ozean auf dem Meeresgrunde vorkommenden Manganknollen. Sitzungsber. Bayer. Akad. Wiss. Math-Phys. KL., 8: 189--209. Meylan, M.A., B~cker, H. and Glasby, GoP., 1975. Manganese nodule investigations in the Southwestern Pacific Basin, 1974. N.Z.O.I. Oceanogr. Field. Rep. No. 4: 24 pp. Murray, J. and Renard, A., 1891. Manganese nodules. In: C.W. Thomson (Editor), Report of the Scientific Results of the Voyage of the HMS Challenger, 5, DeepSea Deposits. Eyre and Spottiswoode, London, pp. 341--378. James E. Stewart, Manoa, Hawaii
interest, a great deal of it represents new and original contributions to the art of mineral exploration that are of general interest and significance. H.E. Hawkes, Orleans, Vermont
OCEANOGRAPHY G.P. Glasby (Editor), 1977. Marine Manganese Deposits. Elsevier Oceanography Series 15. Elsevier, Amsterdam, 523 pp., Dfl. 127.00, U.S. $ 49.00. This is a timely publication in the field of manganese nodule research. Within the next decade nodule deposits from the central Pacific will be commercially exploited -a possibility first suggested over a hundred years ago. First discovered by HMS Challenger, the ferromanganese concretions called manganese nodules have since been found to occur in most of the world's oceans and in many lakes and estuaries. Given the variety of environments in which nodules form it has not yet been possible to identify a unique source for the metals involved -- or a unique mode of formation. The value of this book is in the presentation by its authors of clear reviews of the nature of nodules in the various environments, and the application of the various theories of formation to these settings. It is clear, however, that this is a consolidation of information, rather than a unique set of solutions to the questions about nodules and their growth. It is most interesting that the basic hypotheses of Murray and Renard (1891) and G~mbel (1878) are remarkably current. The slow-growing cryptocrystalline material of the nodules is difficult to work with, and because of the very slow rates of growth involved, even more difficult to model successfully. Environments of growth show a wide variety of physical and chemical parameters, and include: shallow and deep oceanic areas; fresh and salt water, presence or absence of local volcanism; variations in substrate type; and variations in the biogenic contribution to the sediment locally. Thus, a single process cannot be expected to be operative in all cases. Perhaps the single largest failing
304 of the Glasby collection of papers is that the question of environment is treated only in a generalized view, and the reader is left with no insight as to the fine scale of variation in sea-floor environments and in nodule facies, The editor provides in the introductory chapter an historical perspective of the discovery and early investigations of manganese nodules. The reproduction of the Challenger Report figures and the discussion of the early hypotheses for the formation of the nodules are particularly intriguing when contrasted with the modern results on morphology and formation as discussed in Chapters 5 and 10. The distribution of nodules in the oceanic environment is reviewed by D. Cronan. Oceanic in this sense connotes both the basin floor and local and regional volcanic features -- islands and sea mounts, ridges, and oceanic plateaus. For the perspective view this is an excellent chapter; however, for the details of the variations which Cronan discusses the scale of charts are too general and more recent work has refined the boundaries (and mixtures) of the various facies (e.g., Meylan et al., 1975). It would have been quite useful to follow this discussion with a picture of the local facies distribution within such regional nodule deposits, The author's note added in proof (p. 44) points up this problem. Shallow water marine and lacustrine nodules are discussed by Clavert and Price. Lacustrine nodules are quite different from oceanic nodules, in chemistry, substrate relationships, and presumably in growth mechanisms. These nodule types derive their components clearly from the substrate through diagenetic reactions. Their rate of formation is several orders of magnitude more rapid than that of oceanic nodules, Only the very small concretions (pea ores) of this environment morphologically resemble oceanic nodules. These authors also provide a useful discussion of the views on biological activity in the formation of ferromanganese oxides, Fossil nodules have received relatively little attention in the past fifty years. H. Jenkins provides a concise review of this subject. Fossil nodules are known from oceanic, marginal, and littoral environments, and in general are quite similar to their modern-day
counterparts. The littoral forms are of interest as the high manganese/iron ratios reported in modern nodules in this environment have been taken to be a result of diagenetic mobilization in the substrate - a factor which would seem to work against the preservation of fossil nodules. Fossil nodules of the oceanic variety are preserved in obducted sections of oceanic plates, or on structures being uplifted by plate collision or subduction such as the Barbados section. The chapter on morphology by Raab and Meylan discussed the variability and identity of nodule facies. Murray and Renard (1891) reported that a Challenger sample site could be identified from the morphology of the nodules after a brief study of their forms. Unfortunately this chapter concentrates on central Pacific nodules, to the exclusion of facies of great variety in other areas. It would have been most useful if the goals of the first portion o f the chapter had been continued throughout. Internal structure of Pacific nodules is very thoroughly presented by R. Sorem. In addition to providing a well-illustrated guide to the investigation of nodule structures, he presents the relationship between these structures and the theories of growth and formation of the nodules. The chapter on mineralogy is perhaps the most interesting of the book, as it arranges a uniform nomenclature from the mass of manganese oxide mineralogies for application to manganese nodules. Burns and Burns prefer the terms todorokites, birnessite, and $-MnO 2 for the principal minerals in nodules, and demonstrates through crystal chemical considerations how these and related Fe oxyhydroxides may interrelate in the seeding and trace metal enrichment of nodules. Much of this discussion is drawn by inference, as for instance, the crystal structure of todorokite has not yet been determined due to the difficulty in finding single crystals for structural analysis. It is clear also that the strictly controlled crystal chemical relationships are unable to distinguish disturbing events which might have masked their existence subsequent to the growth phases. T.L. Ku reviews the radiometric techniques which have been applied to the dating
305 of nodules and the determination of growth rates, and confirms once again the generally slow rate of accretion for nodules lacking obvious diagenetic or volcanic associations, Episodic nodule growth cannot be discounted entirely, but the data from a number of different dating approaches suggests that such rapid growth intervals are notthe norm, and that they are not necessary in order to maintain the nodules at the sea floor, The formation of manganese and iron in marine sediments and the mechanisms of removal of these and trace metals from sea water are presented in chapters by Elderfield, and by Murray and Brewer. The relative roles of litho,jenous and hydrogenous routs support the crystal models of Burns and Burns. Murray points out that the ages reported for the surfaces of buried nodules are the same as the enclosing sediment which implies metal accretion from sea water or at the sediment/water interface. He favors adsorption as the controlling enrichment mechanism, which makes it unnecessary to involve organic or organo-metal complexes for enrichment. This does not, however, explain the pattern of enriched nodules related to zones of high organic productivity (i.e., the north equatorial Pacific nodule belt), and so leaves open to question a critical step in the enrichment process. From consideration of adsorption processes, Mn should remove more Co than Fe phases, although again this is not always clear in nodule populations. Nodule processing techniques of the industrial groups are proprietary, but various hydrometallurgical techniques have been discussed in general form. Fuerstenau and Han review the known techniques and behavior of the metal species in each. Techniques such as acid leaching, ammonia leaching, chlorination, and smelting all provide different extraction efficiencies for the various metals. The various techniques also present different environmentconsiderations at the plant site. Choices of method will depend on extraction efficiencies for the metals sought (typically Co, Cu and Ni, but possibly including Mn and Mo) and environmental considerations. Amos et al. report on the environmental
effects of mining in the deep ocean. A problem here is that the mid-ocean environment - pelagic and benthic - has not previously been studied at the level of detail necessary to provide the baseline against which environmental impacts can be observed. Such detailed studies are now being carried out in the N O A A DOMES project (Deep Ocean Mining Environmental Studies). The first successful pilot mining tests have also just taken place (OMI aboard the Sedco 445) so that reports on the actual impact will appear shortly. The chapters on economic aspects of nodules, environmental aspects of mining, and legal regimes discuss areas which are rapidly changing with current political and scientific efforts. As this review is being written, the first deep ocean (5,000 m) tests of a hydraulic mining system has been successfully completed, with approximately 1000 tons of nodules mined over a 4 - 5 day interval. Further, the success or failure of the seventh session of the United Nations Law of the Sea conference will shortly provide either the necessary legal regime for licensing and operation of deep ocean mines, or the incentive for national legislation and mini-treaties to accomplish the same end. With this step the technology and legal regimes will be available for the development of the resource.
References G6mbel, W., 1878. Uber die im stillen Ozean auf dem Meeresgrunde vorkommenden Manganknollen. Sitzungsber. Bayer. Akad. Wiss. Math-Phys. KL., 8: 189--209. Meylan, M.A., B~cker, H. and Glasby, GoP., 1975. Manganese nodule investigations in the Southwestern Pacific Basin, 1974. N.Z.O.I. Oceanogr. Field. Rep. No. 4: 24 pp. Murray, J. and Renard, A., 1891. Manganese nodules. In: C.W. Thomson (Editor), Report of the Scientific Results of the Voyage of the HMS Challenger, 5, DeepSea Deposits. Eyre and Spottiswoode, London, pp. 341--378. James E. Stewart, Manoa, Hawaii