scholarly journals Geochemical Fractions of Heavy Metals in Bottom Sediments of the Pobeda Hydrothermal Field, Mid-Atlantic Ridge (17°07′–17°08′ N)

2021 ◽  
Vol 6 (1) ◽  
pp. 14
Author(s):  
Liudmila Demina ◽  
Irina Gablina ◽  
Olga Dara ◽  
Dmitry Budko ◽  
Nina Gorkova ◽  
...  
Keyword(s):  
Total Content ◽  
Element Distribution ◽  
Hydrothermal Field ◽  
Residual Fraction ◽  
Carbonate Sediments ◽  
Metalliferous Sediments ◽  
Geochemical Fractions ◽  
Metalliferous Sediment ◽  
Fe And Mn ◽  
Mid Atlantic Ridge

We examined the distribution of Fe, Mn, Cu, Zn, and Pb in one core of metalliferous, and one core of non-mineralized (background) carbonate sediments (located 69 km northwards), from the Pobeda hydrothermal field. Mechanisms of metal accumulation in sediments (12 samples) were evaluated based on sequential extraction of geochemical fractions, including mobile (exchangeable complex, authigenic Fe-Mn hydroxides, and sulfides), and lithogenic (fixed in crystalline lattices) forms. Maps of element distribution in sediment components were obtained using a scanning electron microscope equipped with an energy-dispersive spectrometry detector. In metalliferous sediments, according to X-ray diffraction data, the main Fe mineral phase was goethite FeOOH (37–44% on a carbonate-free basis). The contents of Fe and Mn reached 31.6 and 0.18%, respectively, whereas concentrations of Cu, Zn and Pb were 0.98, 0.36, and 0.059%. The coefficient of metal enrichment relative to background values varied from 16 to 125 times. The exception was Mn, for which no increased accumulation was recorded. Essential mass of Fe (up to 70% of total content) was represented by the residual fraction composed of crystallized goethite, aluminosilicates, the minerals derived from bedrock destruction processes. Among geochemically mobile fractions, 90–97% of total Fe was found in the form of authigenic oxyhydroxides. The same fraction was the predominant host for Mn in both metalliferous and background sediments (55–85%). A total of 40–96 % of Cd, Cu, Zn, and Pb were associated with these Fe and Mn fractions. The sulfide fraction amounted to roughly 10% of each metal. In metalliferous sediment core, the maximum concentrations of metals and their geochemically mobile fractions were recorded in deeper core intercepts, an observation that might be attributed to influence of hydrothermal diffused fluids. Our data suggested that metals are mostly accumulated in carbonate sediments in their contact zone with the underlying serpentinized basalts.

scholarly journals Geochemical Fractions of Heavy Metals in Bottom Sediments of the Pobeda Hydrothermal Cluster in the Mid-Atlantic Ridge (17°07′–17°08′ N)

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 591
Author(s):  
Liudmila Demina ◽  
Irina Gablina ◽  
Dmitry Budko ◽  
Olga Dara ◽  
Aleksandra Solomatina ◽  
...  
Keyword(s):  
Bottom Sediments ◽  
Sediment Cores ◽  
Total Content ◽  
Total Carbon ◽  
Residual Fraction ◽  
Carbonate Sediments ◽  
Core Sediment ◽  
Metalliferous Sediments ◽  
Geochemical Fractions ◽  
Fe And Mn

In this study, to better understand the influence of hydrothermal processes on ore metal accumulation in bottom sediments, we examined distribution of Fe, Mn, Cu, Zn, As, and Pb in core of metalliferous sediments from the Pobeda hydrothermal cluster, and in core of non-mineralized (background) carbonate sediments (located 69 km northwards). Mechanisms of Fe, Mn, Cu, and Zn accumulation in sediments (12 samples) were evaluated based on sequential extraction of geochemical fractions, including a conditional mobile (F-1, exchangeable complex; F-2, authigenic Fe-Mn oxyhydroxides and associated metals; F-3, metals bound to organic matter/sulfides), and residual (F-4), fixed in crystalline lattices ones. The element contents were determined by the XRF and AAS methods, total carbon (TC) and total organic carbon (TOC) were determined using a Shimadzu TOC-L-CPN. Mineral composition and maps of element distribution in sediment components were obtained using the XRD and SEM-micro-X-ray spectrometry methods, respectively. In metalliferous sediments, according to our data, the major Fe mineral phase was goethite FeOOH (37–44% on a carbonate-free basis, cfb). In the metalliferous core, average contents (cfb), of Fe and Mn were 32.1% and 0.29%, whereas those of Cu, Zn, Pb, and As, were 0.74%, 0.27%, 0.03%, and 0.02%, respectively. Metalliferous sediments are enriched in Fe, Cu, Zn, Pb, and As, relatively to background ones. The exception was Mn, for which no increased accumulation in metalliferous core was recorded. Essential mass of Fe (up to 70% of total content) was represented by the residual fraction composed of crystallized goethite, aluminosilicates, the minerals derived from bedrock destruction processes mineral debris. Among geochemically mobile fractions, to 80% Fe of the (F-1 + F-2 + F-3) sum was determined in the form of F-2, authigenic oxyhydroxides. The same fraction was a predominant host for Mn in both metalliferous and background sediments (to 85%). With these Fe and Mn fractions, a major portion of Cu, Zn, and Pb was associated, while a less their amount was found in sulfide/organic fraction. In the metalliferous sediment core, maximal concentrations of metals and their geochemically mobile fractions were recorded in the deeper core sediment layers, an observation that might be attributed to influence of hydrothermal diffused fluids. Our data suggested that ore metals are mostly accumulated in sediment cores in their contact zone with the underlying serpentinized peridotites.

scholarly journals Mineralogical and Geochemical Signatures of Metalliferous Sediments in Wocan-1 and Wocan-2 Hydrothermal Sites on the Carlsberg Ridge, Indian Ocean

Minerals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 26 ◽  
Author(s):  
Samuel Olatunde Popoola ◽  
Xiqiu Han ◽  
Yejian Wang ◽  
Zhongyan Qiu ◽  
Ying Ye ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Volcanic Glass ◽  
Mineral Chemistry ◽  
Hydrothermal Systems ◽  
Bulk Sediment ◽  
Sediment Samples ◽  
Metalliferous Sediments ◽  
Metalliferous Sediment ◽  
Carlsberg Ridge ◽  
Hydrothermal Environments

In this paper, we conduct a comparative study on the mineralogy and geochemistry of metalliferous sediment collected near the active hydrothermal site (Wocan-1) and inactive hydrothermal site (Wocan-2) from Wocan Hydrothermal Field, on the Carlsberg Ridge (CR), northwest Indian Ocean. We aim to understand the spatial variations in the primary and post-depositional conditions and the intensity of hydrothermal circulations in the Wocan hydrothermal systems. Sediment samples were collected from six stations which includes TVG-07, TVG-08 (Wocan-1), TVG-05, TVG-10 (Wocan-2), TVG-12 and TVG-13 (ridge flanks). The mineralogical investigations show that sediment samples from Wocan-1 and Wocan-2 are composed of chalcopyrite, pyrite, sphalerite, barite, gypsum, amorphous silica, altered volcanic glass, Fe-oxides, and hydroxides. The ridge flank sediments are dominated by biogenic calcite and foraminifera assemblages. The bulk sediment samples of Wocan-1 have an elevated Fe/Mn ratio (up to ~1545), with lower U contents (<7.4 ppm) and U/Fe ratio (<~1.8 × 10−5). The sulfide separates (chalcopyrite, pyrite, and sphalerite) are enriched in Se, Co, As, Sb, and Pb. The calculated sphalerite precipitation temperature (Sph.PT) yields ~278 °C. The sulfur isotope (δ34S) analysis returned a light value of 3.0–3.6‰. The bulk sediment samples of Wocan-2 have a lower Fe/Mn ratio (<~523), with high U contents (up to 19.6 ppm) and U/Fe ratio (up to ~6.2 × 10−5). The sulfide separates are enriched in Zn, Cu, Tl, and Sn. The calculated Sph.PT is ~233 °C. The δ34S returned significant values of 4.1–4.3‰ and 6.4–8.7‰ in stations TVG-10 and TVG-05, respectively. The geochemical signatures (e.g., Fe/Mn and U/Fe ratio, mineral chemistry of sulfides separates, and S-isotopes and Sph.PT) suggest that sediment samples from Wocan-1 are located near intermediate–high temperature hydrothermal discharge environments. Additionally, relatively low δ34S values exhibit a lower proportion (less than 20%) of seawater-derived components. The geochemical signatures suggest that sediment samples from Wocan-2 has undergone moderate–extensive oxidation and secondary alterations by seawater in a low–intermediate temperature hydrothermal environments. Additionally, the significant δ34S values of station TVG-05 exhibit a higher estimated proportion (up to 41%) of seawater-derived components. Our results showed pervasive hydrothermal contributions into station TVG-08 relative to TVG-07, it further showed the increased process of seafloor weathering at TVG-05 relative to TVG-10.

scholarly journals Microbial ecology of the newly discovered serpentinite-hosted Old City hydrothermal field (southwest Indian ridge)

2020 ◽  
Author(s):  
Aurélien Lecoeuvre ◽  
Bénédicte Ménez ◽  
Mathilde Cannat ◽  
Valérie Chavagnac ◽  
Emmanuelle Gérard
Keyword(s):  
Microbial Ecology ◽  
New Caledonia ◽  
Southwest Indian Ridge ◽  
Hydrothermal Field ◽  
Metagenomic Sequencing ◽  
Lost City ◽  
Old City ◽  
Mid Atlantic Ridge ◽  
Indian Ridge ◽  
Geochemical Analyses

Abstract Lost City (mid-Atlantic ridge) is a unique oceanic hydrothermal field where carbonate-brucite chimneys are colonized by a single phylotype of archaeal Methanosarcinales, as well as sulfur- and methane-metabolizing bacteria. So far, only one submarine analog of Lost City has been characterized, the Prony Bay hydrothermal field (New Caledonia), which nonetheless shows more microbiological similarities with ecosystems associated with continental ophiolites. This study presents the microbial ecology of the ‘Lost City’-type Old City hydrothermal field, recently discovered along the southwest Indian ridge. Five carbonate-brucite chimneys were sampled and subjected to mineralogical and geochemical analyses, microimaging, as well as 16S rRNA-encoding gene and metagenomic sequencing. Dominant taxa and metabolisms vary between chimneys, in conjunction with the predicted redox state, while potential formate- and CO-metabolizing microorganisms as well as sulfur-metabolizing bacteria are always abundant. We hypothesize that the variable environmental conditions resulting from the slow and diffuse hydrothermal fluid discharge that currently characterizes Old City could lead to different microbial populations between chimneys that utilize CO and formate differently as carbon or electron sources. Old City discovery and this first description of its microbial ecology opens up attractive perspectives for understanding environmental factors shaping communities and metabolisms in oceanic serpentinite-hosted ecosystems.

Research on the Morphological of Lead and Zinc in the Smelting Slag

2015 ◽  
Vol 1088 ◽  
pp. 200-205
Author(s):  
Lin Yu ◽  
Dong Wei Li
Keyword(s):  
Heavy Metals ◽  
Sequential Extraction ◽  
Ecological Risk ◽  
Total Content ◽  
Residual Fraction ◽  
Bcr Sequential Extraction ◽  
Lead And Zinc ◽  
Smelting Slag ◽  
Reducible Fraction

In this paper analysed the forms of heavy metals (Zn Pb Cd and As) of the Smelting Slag for Lead and Zinc,using BCR sequential extraction. Different chemical morphological of heavy metals have different activity and harmfulness. Migration and Utilization of heavy metals were decided by the existent form of heavy metals in the soil,which influenced Bioactivity and Toxicity. The results show that the main forms of Zn and Cd are Oxidizable and Residual fraction, and Pb mainly occurred in Oxidizable and Reducible fraction. however, As mainly occurred in Residual fraction, which the percentage of reachs 99.56%. According to the percentage of fractions extracted in total content (As is 0.44%, Zn is 14.7%, Pb is 85.98%, Cd is 48.86%),the latent ecological risk of heavy metals varied in the descending order of,Pb Cd Zn and As.

scholarly journals High-resolution multibeam bathymetry of the northern Mid-Atlantic Ridge at 45–46° N: the Moytirra hydrothermal field

2021 ◽  
Vol 17 (2) ◽  
pp. 184-196
Author(s):  
Luis Somoza ◽  
Teresa Medialdea ◽  
Francisco J. González ◽  
Sara Machancoses ◽  
Jose A. Candón ◽  
...  
Keyword(s):  
High Resolution ◽  
Hydrothermal Field ◽  
Multibeam Bathymetry ◽  
Mid Atlantic Ridge

Covellite of the Semenov-2 hydrothermal field (13°31.13′ N, Mid-Atlantic Ridge): Enrichment in trace elements according to LA ICP MS analysis

2017 ◽  
Vol 473 (1) ◽  
pp. 291-295 ◽  
Author(s):  
I. Yu. Melekestseva ◽  
V. V. Maslennikov ◽  
S. P. Maslennikova ◽  
L. V. Danyushevsky ◽  
R. Large
Keyword(s):  
Trace Elements ◽  
Hydrothermal Field ◽  
Ms Analysis ◽  
Icp Ms ◽  
Mid Atlantic Ridge

Geology of a submarine hydrothermal field, Mid-Atlantic Ridge, 26°n latitude

1979 ◽  
Vol 84 (B13) ◽  
pp. 7453-7466 ◽  
Author(s):  
Darcy G. Temple ◽  
Robert B. Scott ◽  
Peter A. Rona
Keyword(s):  
Hydrothermal Field ◽  
Mid Atlantic Ridge

scholarly journals Sulfide Breccias from the Semenov-3 Hydrothermal Field, Mid-Atlantic Ridge: Authigenic Mineral Formation and Trace Element Pattern

Minerals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 321 ◽  
Author(s):  
Irina Melekestseva ◽  
Valery Maslennikov ◽  
Nataliya Safina ◽  
Paolo Nimis ◽  
Svetlana Maslennikova ◽  
...  
Keyword(s):  
Trace Elements ◽  
Hydrothermal Field ◽  
Trace Element Pattern ◽  
Modes Of Occurrence ◽  
Element Pattern ◽  
Authigenic Mineral ◽  
Mid Atlantic Ridge ◽  
Lower Temperature ◽  
Hydrothermal Sulfides

The aim of this paper is the investigation of the role of diagenesis in the transformation of clastic sulfide sediments such as sulfide breccias from the Semenov-3 hydrothermal field (Mid-Atlantic Ridge). The breccias are composed of marcasite–pyrite clasts enclosed in a barite–sulfide–quartz matrix. Primary hydrothermal sulfides occur as colloform, fine-crystalline, porous and radial marcasite–pyrite clasts with inclusions or individual clasts of chalcopyrite, sphalerite, pyrrhotite, bornite, barite and rock-forming minerals. Diagenetic processes are responsible for the formation of more diverse authigenic mineralization including framboidal, ovoidal and nodular pyrite, coarse-crystalline pyrite and marcasite, anhedral and reniform chalcopyrite, inclusions of HgS phase and pyrrhotite–sphalerite–chalcopyrite aggregates in coarse-crystalline pyrite, zoned bornite–chalcopyrite grains, specular and globular hematite, tabular barite and quartz. The early diagenetic ovoid pyrite is enriched in most trace elements in contrast to late diagenetic varieties. Authigenic lower-temperature chalcopyrite is depleted in trace elements relative to high-temperature hydrothermal ones. Trace elements have different modes of occurrence: Se is hosted in pyrite and chalcopyrite; Tl is related to sphalerite and galena nanoinclusions; Au is associated with galena; As in pyrite is lattice-bound, whereas in chalcopyrite it is related to tetrahedrite–tennantite nanoinclusions; Cd in pyrite is hosted in sphalerite inclusions; Cd in chalcopyrite forms its own mineral; Co and Ni are hosted in chalcopyrite.

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