Age and formation conditions of the Co-rich manganese crust on guyots of the Magellan seamounts

Мельников, М. Е.; Плетнев, С. П.

doi:10.1134/s0024490212050057

Cited by 22 publications

(11 citation statements)

References 5 publications

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“…Intense topographical changes on the slope, such as landslides, slope collapse and volcanic activity (which ceased in the Late Cretaceous in this case) on intraplate seamounts 10,42 , play a role in clearing deposits from seamount slopes and burying old deposits on slopes 25 . After past deposits have been removed, the seamount flank would consist exposed rock and would eventually experience build-up of new deposits.…”

Section: Resultsmentioning

confidence: 95%

“…Other sections of shallow drill cores are shown in (b-f) and will be discussed in the following section. www.nature.com/scientificreports/ textural features and stratigraphic chronology 42 . Several previous studies of stratigraphic chronology, such as isotope stratigraphy 44,45 , cobalt concentration 46 , a composite geochemical approach 47 and cobalt-rich crust stratigraphy [48][49][50] , could be used to date cobalt-rich crusts on seamount slopes.…”

Section: Resultsmentioning

confidence: 99%

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Depositional patterns constrained by slope topography changes on seamounts

Yan

Yang

et al. 2020

Sci Rep

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Slope topography is known to control the spatial distribution of deposits on intraplate seamounts; however, relatively little is known about how slope topography changes constrain those depositional patterns. In this study, we analyse data on four lithotypes found on seamount slopes, including colloidal chemical deposits comprising mainly cobalt-rich crusts, and examine the relationships between the spatial distribution of these lithotypes and current slope topography. We use these relationships to discuss depositional patterns constrained by slope topography changes. Some depositional units in drill core samples are interpreted to have resulted from past topographic changes that created the current slope topography. Two or more types of deposits that accumulated at the same location implies that the slope topography changed over time and that the depositional patterns on seamount slopes are constrained by changes in slope topography.

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Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

Depositional patterns constrained by slope topography changes on seamounts

Yan

Yang

et al. 2020

Sci Rep

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“…A thin-layered microstructure prevails in the lower and central parts, and a fine-layered one in the upper part [38]. Thus, the Fe-Mn crust of the Detroit guyot is two-layered and differs strongly from the three-layer crusts of the tropical and subtropical guyots from the Pacific, characterized by the presence of an intermediate section: a porous layer (layer II) [39].…”

Section: Morphologymentioning

confidence: 99%

“…Cracks are visible, both in layers and across it. The upper 18 mm is distinguished by a brownish color and columnar and platy ultrastructures, which, by morphological features, correspond to layer III of the Co-rich crusts [38,39]. The majority of the sample is represented by a pitch-black anthracite layer (layer I).…”

Section: Morphologymentioning

confidence: 99%

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Gold in Ferromanganese Deposits from the NW Pacific

Михайлик

Иванов

2021

Minerals

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Ferromanganese crusts from four different areas of the North-West Pacific Ocean—the Detroit (northern part of the Imperial Ridge) guyot, the Zubov (Marshall Islands) guyot, the “Gummi Bear” seamount (an intraplate volcano near the Krusenstern FZ), and Belyaevsky volcano (the Sea of Japan)—were studied. Samples from the Detroit and Zubov guyots and the “Gummi Bear” seamount have similar chemical and mineral compositions of hydrogenetic cobalt-rich ferromanganese crusts. Crust from the Sea of Japan seems to reflect a hydrothermal influence. The gold content in most samples from the Detroit guyot was 68 ppb and from the Zubov guyot varied from 180 to 1390 ppb, which is higher than the average for the Pacific crusts (55 ppb). Gold content in two other samples was less than 10 ppb. Based on the electron microscopic studies, aggregation of gold particles with a size of 680 μm were identified in the Detroit guyot crust. The sizes of the Au particles are up to 10–15 μm, which has not been previously noted. Gold particles similar in morphology and size were also found in the Zubov guyot crust, which is located far from the Detroit guyot. The largest particle of gold (≈60 μm), represented by electrum, was found in the clay substrate from the “Gummi Bear” seamount. The lamellar, rudaceous morphology of the gold particles from the Detroit and Zubov guyots reflects their in situ formation, in contrast to the agglutinated, rounded with traces of dragging gold grain found in the substrate of the sample from the “Gummi Bear” seamount. Three-component (Ag-Au-Cu) gold particles were found in the hydrothermal crust from the Belyaevsky underwater volcano. Grains similar in composition were also found in Co-rich crust. The research results show that the gold was probably added to by hydrothermal fluid in the already-formed hydrogenetic ferromanganese crusts during rejuvenated volcanic stages. Biogeochemical processes may have played a major role in the formation of submicron solid-phase gold particles.

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Depth-Dependent Distribution of Prokaryotes in Sediments of the Manganese Crust on Nazimov Guyots of the Magellan Seamounts

Sun,

Zhou,

Cheng

et al. 2023

Microb Ecol

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Deep ocean polymetallic nodules, rich in cobalt, nickel, and titanium which are commonly used in high-technology and biotechnology applications, are being eyed for green energy transition through deep-sea mining operations. Prokaryotic communities underneath polymetallic nodules could participate in deep-sea biogeochemical cycling, however, are not fully described. To address this gap, we collected sediment cores from Nazimov guyots, where polymetallic nodules exist, to explore the diversity and vertical distribution of prokaryotic communities. Our 16S rRNA amplicon sequencing data, quantitative PCR results and phylogenetic beta diversity indices showed that prokaryotic diversity in the sur cial layers (0-8 cm) was > 4-fold higher compared to deeper horizons (8-26 cm), while heterotrophs dominated in all sediment horizons. Proteobacteria was the most abundant taxon (32-82%) across all sediment depths, followed by Thaumarchaeota (4-37%), Firmicutes (2-18%) and Planctomycetes (1-6%). Depth was the key factor controlling prokaryotic distribution, while heavy metals (e.g., iron, copper, nickel, cobalt, zinc) can also in uence signi cantly the downcore distribution of prokaryotic communities. Analyses of phylogenetic diversity showed that deterministic processes governing prokaryotic assembly in sur cial layers, contrasting with stochastic in uences in deep layers. This was further supported from the detection of a more complex prokaryotic cooccurrence network in the sur cial layer which suggested more diverse prokaryotic communities existed in the surface vs. deeper sediments. This study expands current knowledge on the vertical distribution of benthic prokaryotic diversity in deep sea settings underneath polymetallic nodules, and the results reported might set a baseline for future mining decisions. Sample Collection and Environmental CharacterizationOne sediment core was collected from surface to 26 cm below sea oor (cmbsf) at the Nazimov guyots in Magellan seamount (162.45 °E, 15.18 °N, 5365 m seawater depth) using a four-tube multitube sampler (MC-400, 10×58 cm, Ocean Environmental Sci.&Tech.) during the Dayang 61st-I cruise of P. R. China. Brie y, the sediment core was sliced at 2-cm intervals with a stainless-steel cutter at 13 different sediment intervals (n = 13 samples). A sterile spatula was used to carefully collect sediment from the center of each sediment horizon for DNA extraction to avoid potential contamination. Samples were transferred to sterilized plastic tubes and stored at -80 °C until DNA extraction, and analyses of selected environmental factors like pH, electrical conductivity (EC), available phosphorous (AP), available potassium (AK), available nitrogen (AN), and organic carbon (OC), according to [30,31]. We note that our analyses on AN and AP provide bulk estimations of available N and P in the sediments without further speciation on the contribution of inorganic vs. organic sources. Brie y, samples were air-dried at room temperature in the shade and sieved through a 2-mm screen. The pH an...

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Age and formation conditions of the Co-rich manganese crust on guyots of the Magellan seamounts

Cited by 22 publications

References 5 publications

Depositional patterns constrained by slope topography changes on seamounts

Depositional patterns constrained by slope topography changes on seamounts

Gold in Ferromanganese Deposits from the NW Pacific

Depth-Dependent Distribution of Prokaryotes in Sediments of the Manganese Crust on Nazimov Guyots of the Magellan Seamounts

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