Formation age of the dual structure and environmental change recorded in hydrogenetic ferromanganese crusts from Northwest and Central Pacific seamounts

Nishi, Keisuke; Usui, Akira; Nakasato, Yoshio; Yasuda, Hisato

doi:10.1016/j.oregeorev.2016.09.004

Cited by 35 publications

(10 citation statements)

References 29 publications

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“…Overlaying the S ratio map on the optical image (Figure d) shows that dark areas (voids) between columnar structures on the optical image are closely correlated with the areas with S ratio lower than 0.7. Nishi et al [] reported that the columnar structure is associated with fine‐grained detritus, whereas the voids in‐between are associated with coarse‐grained detritus. Thus, coarse‐grained detritus in voids is generally associated with the higher coercivity minerals, such as hematite or goethite.…”

Section: Resultsmentioning

confidence: 99%

“…Stable isotopes, such as Os, can be used to construct age models [e.g., Nielsen et al, 2011;Goto et al, 2016] by correlation with the long-term seawater master curve obtained from sediments. Geochronology based on cosmogenic nuclides, such as 10 Be/ 9 Be, is increasingly popular [e.g., Nielsen et al, 2011;Nishi et al, 2017;Usui et al, 2017] for age models younger than~15 Ma. In recent years, magnetostratigraphy, which is a completely different geophysical method based on paleomagnetism, has emerged as an alternative method to estimate the age models of ferromanganese crusts [e.g., Joshima and Usui, 1998;Oda et al, 2011;Noguchi et al, 2017].…”

Section: Introductionmentioning

confidence: 99%

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Scanning SQUID microscopy of a ferromanganese crust from the northwestern Pacific: Submillimeter scale magnetostratigraphy as a new tool for age determination and mapping of environmental magnetic parameters

Noguchi

Oda

Yamamoto

et al. 2017

Geophysical Research Letters

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Ferromanganese crusts record long‐term deep‐sea environmental changes. Thus, providing their reliable high‐resolution age models is important. We applied a magnetostratigraphic technique to estimate the growth rate of a ferromanganese crust using scanning SQUID (superconducting quantum interference device) microscope (SSM). SSM is designed to map the magnetic field across thin sections with submillimeter resolution. The crust sample was taken from the Takuyo‐Daigo Seamount, northwestern Pacific, and recorded a limited supply of dust and sediment from continents. After drift correction and removal of spike noises, the magnetic field values were stacked within the areas of high signal‐to‐noise ratios. By correlating the obtained profiles with a standard geomagnetic polarity timescale, we obtained an average growth rate of 3.37 ± 0.06 mm/Ma, which is consistent with that obtained by 10Be/9Be geochronology (2.93 ± 0.15 mm/Ma). S ratio mapping shows low values after ~3 Ma, associated with voids between columnar structures.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Scanning SQUID microscopy of a ferromanganese crust from the northwestern Pacific: Submillimeter scale magnetostratigraphy as a new tool for age determination and mapping of environmental magnetic parameters

Noguchi

Oda

Yamamoto

et al. 2017

Geophysical Research Letters

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“…Although thick Fe-Mn crusts from many northwest and central Pacific seamounts also present two crust generations with an older phosphatized crust and a younger non-phosphatized crust [54][55][56][57], the phosphatization of the first crust generation of RGR is more pervasive and intense. The phosphatized older crust generations from the Pacific seamounts have P contents of up to 5.5% [54,58,59].…”

Section: Two Generations Of Fe-mn Crusts On Rio Grande Risementioning

confidence: 99%

“…The formation of 10 Å phyllomanganate in a Fe-Mn crust may occur due to the less-oxidizing conditions associated with phosphatization [56]. All the phosphatized generations of the crusts from the RGR plateau had a 10 Å phyllomanganate phase, while only two out of 10 non-phosphatized crusts layers contained this phase.…”

Section: Two Generations Of Fe-mn Crusts On Rio Grande Risementioning

confidence: 99%

Genesis and Evolution of Ferromanganese Crusts from the Summit of Rio Grande Rise, Southwest Atlantic Ocean

et al. 2020

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The Rio Grande Rise (RGR) is a large elevation in the Atlantic Ocean and known to host potential mineral resources of ferromanganese crusts (Fe–Mn), but no investigation into their general characteristics have been made in detail. Here, we investigate the chemical and mineralogical composition, growth rates and ages of initiation, and phosphatization of relatively shallow-water (650–825 m) Fe–Mn crusts dredged from the summit of RGR by using computed tomography, X-ray diffraction, 87Sr/86Sr ratios, U–Th isotopes, and various analytical techniques to determine their chemical composition. Fe–Mn crusts from RGR have two distinct generations. The older one has an estimated age of initiation around 48–55 Ma and was extensively affected by post-depositional processes under suboxic conditions resulting in phosphatization during the Miocene (from 20 to 6.8 Ma). As a result, the older generation shows characteristics of diagenetic Fe–Mn deposits, such as low Fe/Mn ratios (mean 0.52), high Mn, Ni, and Li contents and the presence of a 10 Å phyllomanganate, combined with the highest P content among crusts (up to 7.7 wt %). The younger generation is typical of hydrogenetic crusts formed under oxic conditions, with a mean Fe/Mn ratio of 0.75 and mean Co content of 0.66 wt %, and has the highest mean contents of Bi, Nb, Ni, Te, Rh, Ru, and Pt among crusts formed elsewhere. The regeneration of nutrients from local biological productivity in the water column is the main source of metals to crusts, providing mainly metals that regenerate rapidly in the water column and are made available at relatively shallow water depths (Ni, As, V, and Cd), at the expense of metals of slower regeneration (Si and Cu). Additionally, important contributions of nutrients may derive from various water masses, especially the South Atlantic Mode Water and Antarctic Intermediate Water (AAIW). Bulk Fe–Mn crusts from the summit of RGR plateau are generally depleted in metals considered of greatest economic interest in crusts like Co, REE, Mo, Te, and Zr, but are the most enriched in the critical metals Ni and Li compared to other crusts. Further investigations are warranted on Fe–Mn crusts from deeper-water depths along the RGR plateau and surrounding areas, which would less likely be affected by phosphatization.

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“…Ferromanganese (Fe-Mn) deposits are present in the oceans across the world, marine ridges, and plateaus where the currents have delivered sediments for millions of years [1]. These deposits form through the accumulation of iron and manganese oxides in seawater, within either volcanic or sedimentary rocks that act as substrates, as observed in the central and northeastern ocean beds of the Pacific [2]. They may have economic potential [3], due to the high concentrations of Co, Ni, Te, Ti, Pt, and rare earth elements [4].…”

Section: Introductionmentioning

confidence: 99%

Leaching of Manganese from Marine Nodules at Room Temperature with the Use of Sulfuric Acid and the Addition of Tailings

et al. 2019

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Based on the results obtained from a previous study investigating the dissolution of Mn from marine nodules with the use of sulfuric acid and foundry slag, a second series of experiments was carried out using tailings produced from slag flotation. The proposed approach takes advantage of the Fe present in magnetite contained in these tailings and is believed to be cost-efficient. The surface optimization methodology was used to evaluate the independent variables of time, particle size, and sulfuric acid concentration in the Mn solution. Other tests evaluated the effect of agitation speed and the MnO2/Fe2O3 ratio in an acid medium. The highest Mn extraction rate of 77% was obtained with an MnO2/Fe2O3 ratio of 1/2 concentration of 1 mol/L of H2SO4, particle size of −47 + 38 μm, and 40 min of leaching. It is concluded that higher rates of Mn extraction were obtained when tailings instead of slag were used, while future research needs to focus on determination of the optimum Fe2O3/MnO2 ratio to improve dissolution of Mn from marine nodules.

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Formation age of the dual structure and environmental change recorded in hydrogenetic ferromanganese crusts from Northwest and Central Pacific seamounts

Cited by 35 publications

References 29 publications

Scanning SQUID microscopy of a ferromanganese crust from the northwestern Pacific: Submillimeter scale magnetostratigraphy as a new tool for age determination and mapping of environmental magnetic parameters

Scanning SQUID microscopy of a ferromanganese crust from the northwestern Pacific: Submillimeter scale magnetostratigraphy as a new tool for age determination and mapping of environmental magnetic parameters

Genesis and Evolution of Ferromanganese Crusts from the Summit of Rio Grande Rise, Southwest Atlantic Ocean

Leaching of Manganese from Marine Nodules at Room Temperature with the Use of Sulfuric Acid and the Addition of Tailings

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