Composition and parageneses of massive pyrolusite from the deep-water basin of the Sea of Japan

Астахова, Н. В.; Lopatnikov, E. A.

doi:10.1016/j.rgg.2016.09.003

Cited by 2 publications

(1 citation statement)

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“…DW778D, DW778D2 and DW778B were dredged on the summit of Mount K, a volcanic edifice of the Loyalty Ridge that is likely subduction related (Figure 2B). The presence of both amorphous and crystalline 10 Å manganate (±pyrolusite), and the pseudolayered structure observed at the macro and microscopic scales in the DW778 samples, are consistent with other oceans hydrothermal deposits [11][12][13]86]. Hydrothermal deposits originating from ascending fluids are known to form in distal parts of the venting site in several geomorphological environments: back-arc basins [12,13], arc systems [11,69,87,88], or hot spot volcanoes [67,89,90].…”

Section: Nature Of Non-hydrogenetic Depositssupporting

confidence: 79%

Origin and Composition of Ferromanganese Deposits of New Caledonia Exclusive Economic Zone

et al. 2022

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Located in the South-West Pacific, at the northern extremity of the mostly submerged Zealandia continent, the New Caledonian Exclusive Economic Zone (EEZ) covers 1,470,000 km² and includes basins, ridges and seamounts where abundant ferromanganese crusts have been observed. Several investigations have been conducted since the 1970s on the nature and composition of ferromanganese crusts from New Caledonia’s seamounts and ridges, but none have covered the entire EEZ. We present data from 104 ferromanganese crusts collected in New Caledonia’s EEZ during twelve oceanographic cruises between 1974 and 2019. Samples were analysed for mineralogy, geochemical compositions, growth rates, and through a statistical approach using correlation coefficients and factor analysis. Crust thicknesses range from 1 mm to 115 mm, with growth rates between 0.45 mm/Ma and 102 mm/Ma. Based on textures, structures, discrimination plots, and growth rates, we distinguish a group of hydrogenetic crusts containing the highest mean contents of Co (0.42 wt%), Ni (0.31 wt%), and high contents of Mo, V, W, Pb, Zn, Nb, from a group of hydrothermal and/or diagenetic deposits showing high mean contents of Mn (38.17 wt%), Ba (0.56 wt%) and low contents of other trace metals. Several samples from this later group have exceptionally high content of Ni (0.7 wt%). The data shows that crusts from the southern part of the EEZ, notably seamounts of the Loyalty Ridge and the Lord Howe Rise, present high mineral potential for prospectivity owing to high contents of valuable metals, and constitute a great target for further investigation.

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