Geochemistry of ferromanganese crusts from the Hawaiian Archipelago—I. Northern survey areas

Carlo, Eric Heinen De; McMurthy, Gary M.; Kim, Kee Hyun

doi:10.1016/0198-0149(87)90147-6

Cited by 68 publications

(22 citation statements)

References 33 publications

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“…Elements distributed in Fe‐Mn crusts can often be grouped based on correlation and likely origin [e.g., De Carlo et al , 1987; De Carlo and McMurtry , 1992; Wen et al , 1997]. These groups are: hydrogenous (Mn, Co, Ni, and Mo), biogenic (Cu, Zn, and Ba ex ), detrital (Al, Ti, K and Rb), and CFA (Ca and P).…”

Section: Resultsmentioning

confidence: 99%

Southward shift of the Intertropical Convergence Zone in the western Pacific during the late Tertiary: Evidence from ferromanganese crusts on seamounts west of the Marshall Islands

et al. 2006

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Hydrogenetic ferromanganese crusts were dredged from four seamounts in the western Pacific, OSM7, OSM2, Lomilik, and Lemkein, aligned in a NW‐SE direction parallel to Pacific Plate movement. The crusts consist of four well‐defined layers with distinct textural and geochemical properties. The topmost layer 1 is relatively enriched in Mn, Co, Ni, and Mo compared to the underlying layer 2, which is relatively enriched in Al, Ti, K, and Rb and Cu, Zn, and excess Ba. Textural and geochemical properties of layer 2 suggest growth conditions under high biogenic and detrital flux. Such conditions are met in the equatorial Pacific (i.e., between the Intertropical Convergence Zone (ITCZ) and equatorial high‐productivity zone). Layer 2 likely formed when each seamount was beneath the equatorial Pacific along its back track path. On the other hand, layer 1 probably started to grow after seamounts moved northwest from the ITCZ. This interpretation is consistent with the thickness of layer 1 across the four crusts, which increases to the northwest. Ages of the layer 1–layer 2 boundary in each crust, a potential proxy for northern margin of the ITCZ, also increase to the northwest at 17, 11, 8, and 5 Ma for OSM7, OSM2, Lomilik, and Lemkein, respectively. Assuming Pacific Plate motion of 0.3°/Myr, the seamounts were located at 12°N, 11°N, 9°N, and 8°N at the time of boundary formation. This result suggests that the north edge of the ITCZ has shifted south since the middle Miocene in the western Pacific, which agrees with information from the eastern Pacific.

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Section: Resultsmentioning

confidence: 99%

Southward shift of the Intertropical Convergence Zone in the western Pacific during the late Tertiary: Evidence from ferromanganese crusts on seamounts west of the Marshall Islands

et al. 2006

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“…Mining of cobalt-rich manganese crusts on the upper slopes and summits of seamounts is likely to take place in the Central Pacific Basin because (1) the crusts are richer in metal content and more extensively distributed than previously recognized, (2) many crust deposits are situated within Exclusive Economic Zones of island nations seeking economic development, (3) the deposits occur at relatively shallow depths compared to manganese nodules and (4) these deposits provide alternate sources of strategic minerals and rare earth elements. Manganese crust resource studies have been carried out in several seamount chains in the Central Pacific Basin by Japanese, French, and German scientists.…”

Section: Introductionmentioning

confidence: 99%

Morphology of Central Pacific Seamounts: Implications for Mn-Crust Mining

Keating

1989

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Mining of cobalt-rich manganese crusts in the upper slopes and summits of seamounts, is likely to take place in the Central Pacific Basin. The distribution, abundance, and mineralogy of these deposits are influenced by their geologic setting. The mineral deposits are generally thickest on the most stable (least mobile) substrates. But they will be most readily mined on friable substrates (such as volcanic breccias). Characteristics conducive to mining include: minimum slope angles, relative absence of bathymetric obstacles (benches, fault scarps, and volcanic features), absence of poorly consolidated sediments which minimize manganese crust growth, and presence of amenable substrates. On the basis of these criteria large portions of the Line Islands chain are targets for marine mining. Many of the seamounts within the Line Island group, however, are characterized by rejuvenated volcanism, which has resulted in very rugged summits and a thick mantling of the seamount with volcanoclastic rocks. In order to successfully mine crusts from the Line Islands seamounts, site specific surveys will be needed to identify sites with minimal bathymetric obstacles. Small, very mobile mining devices would be appropriate for this rugged terrain. INTRODUCTION Mining of cobalt-rich manganese crusts on the upper slopes and summits of seamounts is likely to take place in the Central Pacific Basin because (1) the crusts are richer in metal content and more extensively distributed than previously recognized, (2) many crust deposits are situated within Exclusive Economic Zones of island nations seeking economic development, (3) the deposits occur at relatively shallow depths compared to manganese nodules and (4) these deposits provide alternate sources of strategic minerals and rare earth elements. Manganese crust resource studies have been carried out in several seamount chains in the Central Pacific Basin by Japanese, French, and German scientists. The proposed Sale of Marine Mineral leases in the Hawaiian Archipelago and Johnston Island Exclusive Economic Zones raises the possibility of manganese crust mining on seamounts in the Hawaiian and Line Islands seamount chains. Since the distribution, abundance and mineralogy of the manganese crusts are strongly influenced by their geologic setting, it is important that we gain a clearer understanding of the geologic setting in which manganese crusts are formed. Geological and geophysical studies of Central Pacific seamounts of the Hawaiian, Line, Gilbert and Phoenix Islands (Fig. 1) indicate that the distribution of bathymetric features, seamount shapes, and substrates vary significantly from one province to another. These reflect differences in geologic history of the seamount provinces. In this paper, seamount characteristics are compared for the Line Islands (Island nation of Kiribati) and Hawaiian seamount chains. Examination of seamounts in the Hawaiian chain show limited resources, because of the youth of the seamount chain. Resource potential is greater in the Line Islands seamount chain, in large part because the crusts are much thicker in that seamount chain. The Line Islands chain however is characterized by rough topography, which would make mining using conventional dredge-type apparatus difficult.

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“…Co-rich ferromanganese crusts occurring on submarine guyots have received much attention from scientists since the beginning of the 1980's because they are enriched in Co, Mn, Pt, and rare earth elements (REEs), and have large potential mineral resources, occumng as they do on topographic highs relative to polymetallic nodules in the C-C (Clarion-Clipperton) zone (Halbach et al, 1982(Halbach et al, , 1989Hein et al, 1992Hein et al, , 1999Usui and Someya, 1997;Yamazaki andSharma, 1998,2000;De Carlo et al, 1987;Pan et al, 1999;Wen et al. 1997).…”

Section: Introductionmentioning

confidence: 99%

Effect of Phosphatization on Element Concentration of Cobalt-Rich Ferromanganese Crusts

Jiahua¹,

Carlo

Yang

et al. 2005

Acta Geologica Sinica - English Edition

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Geochemistry of ferromanganese crusts from the Hawaiian Archipelago—I. Northern survey areas

Cited by 68 publications

References 33 publications

Southward shift of the Intertropical Convergence Zone in the western Pacific during the late Tertiary: Evidence from ferromanganese crusts on seamounts west of the Marshall Islands

Southward shift of the Intertropical Convergence Zone in the western Pacific during the late Tertiary: Evidence from ferromanganese crusts on seamounts west of the Marshall Islands

Morphology of Central Pacific Seamounts: Implications for Mn-Crust Mining

Effect of Phosphatization on Element Concentration of Cobalt-Rich Ferromanganese Crusts

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