Hydrothermal nontronite formation associated with microbes from low-temperature diffuse hydrothermal vents at the South Mid-Atlantic Ridge

2017 ◽  
Vol 122 (9) ◽  
pp. 2375-2392 ◽  
Author(s):  
Kaiwen Ta ◽  
Xiaotong Peng ◽  
Shun Chen ◽  
Hengchao Xu ◽  
Jiwei Li ◽  
...  
Keyword(s):  
Low Temperature ◽  
Hydrothermal Vents ◽  
The South ◽  
Mid Atlantic Ridge

scholarly journals A seawater throttle on H2production in Precambrian serpentinizing systems

2020 ◽  
Vol 117 (26) ◽  
pp. 14756-14763 ◽  
Author(s):  
Benjamin M. Tutolo ◽  
William E. Seyfried ◽  
Nicholas J. Tosca
Keyword(s):  
Low Temperature ◽  
Hydrothermal Vents ◽  
Oxidation States ◽  
Ridge Axis ◽  
Secular Changes ◽  
Mid Atlantic Ridge ◽  
Initial Discovery ◽  
The Origin Of Life ◽  
Microbial Systems ◽  
Alkaline Hydrothermal Vents

Since the initial discovery of low-temperature alkaline hydrothermal vents off the Mid-Atlantic Ridge axis nearly 20 y ago, the observation that serpentinizing systems produce abundant H2has strongly influenced models of atmospheric evolution and geological scenarios for the origin of life. Nevertheless, the principal mechanisms that generate H2in these systems, and how secular changes in seawater composition may have modified serpentinization-driven H2fluxes, remain poorly constrained. Here, we demonstrate that the dominant mechanism for H2production during low-temperature serpentinization is directly related to a Si deficiency in the serpentine structure, which itself is caused by low SiO2(aq) concentrations in serpentinizing fluids derived from modern seawater. Geochemical calculations explicitly incorporating this mechanism illustrate that H2production is directly proportional to both the SiO2(aq) concentration and temperature of serpentinization. These results imply that, before the emergence of silica-secreting organisms, elevated SiO2(aq) concentrations in Precambrian seawater would have generated serpentinites that produced up to two orders of magnitude less H2than their modern counterparts, consistent with Fe-oxidation states measured on ancient igneous rocks. A mechanistic link between the marine Si cycle and off-axis H2production requires a reevaluation of the processes that supplied H2to prebiotic and early microbial systems, as well as those that balanced ocean–atmosphere redox through time.

scholarly journals Identification of Two New Hydrothermal Fields and Sulfide Deposits on the Mid-Atlantic Ridge as a Result of the Combined Use of Exploration Methods: Methane Detection, Water Column Chemistry, Ore Sample Analysis, and Camera Surveys

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 726
Author(s):  
Sergei Sudarikov ◽  
Egor Narkevsky ◽  
Vladimir Petrov
Keyword(s):  
Low Temperature ◽  
Hydrothermal Vents ◽  
Hydrothermal Activity ◽  
Neutral Buoyancy ◽  
Combined Use ◽  
Bottom Waters ◽  
Mid Atlantic Ridge ◽  
Hydrothermal Plumes ◽  
Geochemical Studies ◽  
Hydrothermal Fields

In 2018–2020 the research vessel (R/V) Professor Logachev (cruises 39 and 41) carried out geological and geochemical studies in the bottom waters of the Mid-Atlantic Ridge hydrothermal fields at 14°45’ N, 13°07’ N, and 13°09’ N. Two new hydrothermal fields were discovered—the Molodezhnoye and Koralovoye. Standard conductivity, temperature, and depth (CTD) sounding with a methane sensor was accompanied by video surveillance and sampling of rocks and water. The rocks were characterized by a zonal composition with opal and sulfides of copper and zinc. An increase in methane concentration values was accompanied by CTD anomalies in the bottom waters. The methane anomaly was formed within the hydrothermal plume of both high-temperature and low-temperature systems. Methane was almost absent in the plume of neutral buoyancy and was associated in all the studied manifestations with the ascending flow of hot waters over the hydrothermal vents. The hydrothermal plumes were characterized by increased Cu, Zn, and Fe concentrations at background Mn concentrations. Signs of low-temperature hydrothermal activity were also observed. Different sources and mechanisms are required to explain the elevated concentrations of base metals and methane in the hydrothermal plumes.

Hydrothermal vents near a mantle hot spot: the Lucky Strike vent field at 37°N on the Mid-Atlantic Ridge

1997 ◽  
Vol 148 (1-2) ◽  
pp. 69-91 ◽  
Author(s):  
C. Langmuir ◽  
S. Humphris ◽  
D. Fornari ◽  
C. Van Dover ◽  
K. Von Damm ◽  
...  
Keyword(s):  
Hydrothermal Vents ◽  
Hot Spot ◽  
Lucky Strike ◽  
Mid Atlantic Ridge

scholarly journals Sr–Nd–Pb–Hf Isotopic Constraints on the Mantle Heterogeneities beneath the South Mid-Atlantic Ridge at 18–21°S

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1010
Author(s):  
Yun Zhong ◽  
Xu Zhang ◽  
Zhilei Sun ◽  
Jinnan Liu ◽  
Wei Li ◽  
...  
Keyword(s):  
Isotopic Data ◽  
The South ◽  
Mantle Heterogeneities ◽  
Depleted Mantle ◽  
Mid Ocean Ridge ◽  
Trace Elemental ◽  
Heterogeneous Mantle ◽  
Mid Atlantic Ridge ◽  
St Helena ◽  
Ocean Ridge

In an attempt to investigate the nature and origin of mantle heterogeneities beneath the South Mid-Atlantic Ridge (SMAR), we report new whole-rock Sr, Nd, Pb, and Hf isotopic data from eight basalt samples at four dredge stations along the SMAR between 18°S and 21°S. Sr, Nd, and Pb isotopic data from SMAR mid-ocean ridge basalts (MORBs) at 18–21°S published by other researchers were also utilized in this study. The SMAR MORBs at 18–21°S feature the following ratio ranges: 87Sr/86Sr = 0.70212 to 0.70410, 143Nd/144Nd = 0.512893 to 0.513177, 206Pb/204Pb = 18.05 to 19.50, 207Pb/204Pb = 15.47 to 15.71, 208Pb/204Pb = 37.87 to 38.64, and 176Hf/177Hf = 0.283001 to 0.283175. The 87Sr/86Sr, 143Nd/144Nd, 206Pb/204Pb, and 176Hf/177Hf ratios of these MORBs varied considerably along the SMAR axis. The variable compositions of the Sr–Nd–Pb–Hf isotopes, combined with the corresponding whole-rock major and trace elemental abundances reported in previous studies, suggest that the SMAR MORBs at 18–21°S were probably derived from a heterogeneous mantle substrate related to a mixture of depleted mantle (DM) materials with a small amount (but variable input) of HIMU (high-μ, where μ = 238U/204Pb)- and enriched (EMII)-type materials. The HIMU-type materials likely originated from the proximal St. Helena plume and may have been transported through “pipe-like inclined sublithospheric channels” into the SMAR axial zone. The EMII-type materials possibly originated from a recycled metasomatized oceanic crust that may have been derived from the early dispersion of other plume heads into the subcontinental asthenosphere prior to the opening of the South Atlantic Ocean. In addition, the contributions of subducted sediments, continental crust, and subcontinental lithospheric mantle components to the formation of the SMAR MORBs at 18–21°S may be nonexistent or negligible.

scholarly journals Pyrite Varieties at Pobeda Hydrothermal Fields, Mid-Atlantic Ridge 17°07′–17°08′ N: LA-ICP-MS Data Deciphering

Minerals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 622
Author(s):  
Valeriy Maslennikov ◽  
Georgy Cherkashov ◽  
Dmitry Artemyev ◽  
Anna Firstova ◽  
Ross Large ◽  
...  
Keyword(s):  
Low Temperature ◽  
Massive Sulfide ◽  
Black Smoker ◽  
Fine Grained ◽  
Framboidal Pyrite ◽  
Icp Ms ◽  
Mid Atlantic Ridge ◽  
Seafloor Massive Sulfide ◽  
Hydrothermal Fields ◽  
Feeder Zone

The massive sulfide ores of the Pobeda hydrothermal fields are grouped into five main mineral microfacies: (1) isocubanite-pyrite, (2) pyrite-wurtzite-isocubanite, (3) pyrite with minor isocubanite and wurtzite-sphalerite microinclusions, (4) pyrite-rich with framboidal pyrite, and (5) marcasite-pyrite. This sequence reflects the transition from feeder zone facies to seafloor diffuser facies. Spongy, framboidal, and fine-grained pyrite varieties replaced pyrrhotite, greigite, and mackinawite “precursors”. The later coarse and fine banding oscillatory-zoned pyrite and marcasite crystals are overgrown or replaced by unzoned subhedral and euhedral pyrite. In the microfacies range, the amount of isocubanite, wurtzite, unzoned euhedral pyrite decreases versus an increasing portion of framboidal, fine-grained, and spongy pyrite and also marcasite and its colloform and radial varieties. The trace element characteristics of massive sulfides of Pobeda seafloor massive sulfide (SMS) deposit are subdivided into four associations: (1) high temperature—Cu, Se, Te, Bi, Co, and Ni; (2) mid temperature—Zn, As, Sb, and Sn; (3) low temperature—Pb, Sb, Ag, Bi, Au, Tl, and Mn; and (4) seawater—U, V, Mo, and Ni. The high contents of Cu, Co, Se, Bi, Te, and values of Co/Ni ratios decrease in the range from unzoned euhedral pyrite to oscillatory-zoned and framboidal pyrite, as well as to colloform and crystalline marcasite. The trend of Co/Ni values indicates a change from hydrothermal to hydrothermal-diagenetic crystallization of the pyrite. The concentrations of Zn, As, Sb, Pb, Ag, and Tl, as commonly observed in pyrite formed from mid- and low-temperature fluids, decline with increasing crystal size of pyrite and marcasite. Coarse oscillatory-zoned pyrite crystals contain elevated Mn compared to unzoned euhedral varieties. Framboidal pyrite hosts maximum concentrations of Mo, U, and V probably derived from ocean water mixed with hydrothermal fluids. In the Pobeda SMS deposit, the position of microfacies changes from the black smoker feeder zone at the base of the ore body, to seafloor marcasite-pyrite from diffuser fragments in sulfide breccias. We suggest that the temperatures of mineralization decreased in the same direction and determined the zonal character of deposit.

scholarly journals Food sources, behaviour, and distribution of hydrothermal vent shrimps at the Mid-Atlantic Ridge

2000 ◽  
Vol 80 (3) ◽  
pp. 485-499 ◽  
Author(s):  
A.V. Gebruk ◽  
E.C. Southward ◽  
H. Kennedy ◽  
A.J. Southward
Keyword(s):  
Hydrothermal Vents ◽  
Food Sources ◽  
Larval Stages ◽  
Rimicaris Exoculata ◽  
Tube Worms ◽  
The Pacific ◽  
Mid Atlantic Ridge ◽  
Menez Gwen ◽  
Juvenile Shrimp ◽  
Supporting Structures

Five species of bresilioid shrimp were investigated at seven hydrothermal sites on the Mid-Atlantic Ridge: Menez Gwen, Lucky Strike, Rainbow, Broken Spur, TAG, Snake Pit and Logatchev. Samples were prepared for analysis of stable isotopes, elemental composition and lipids. Shrimp behaviour was observed from the submersible ‘Alvin’ and in the laboratory aboard RV ‘Atlantis’. The distribution and zonation of the shrimp species was recorded. Juvenile shrimp of all species arrive at the vents carrying reserves of photosynthetic origin, built-up in the pelagic larval stages. These reserves are used while the shrimp metamorphose to the adult form and, in Rimicaris exoculata and Chorocaris chacei, while they develop epibiotic bacteria supporting structures, the modified mouthparts and the inside of the carapace. The main food of adult R. exoculata is filamentous bacteria that grow on these structures. The intermediate sizes of C. chacei also feed on such bacteria, but the final stage gets some food by scavenging or predation. Mirocaris species scavenge diverse sources; they are not trophically dependent on either R. exoculata or mussels. Adults of Alvinocaris markensis are predators of other vent animals, including R. exoculata. The dense swarms of R. exoculata, with their exosymbionts, can be compared to endosymbiont-containing animals such as Bathymodiolus and the vestimentiferan tube-worms of the Pacific vents. Such associations, whether endo- or ectosymbiotic, may be necessary for the development of flourishing communities at hydrothermal vents.

A novel eye in 'eyeless' shrimp from hydrothermal vents of the Mid-Atlantic Ridge

Nature ◽  
1989 ◽  
Vol 337 (6206) ◽  
pp. 458-460 ◽  
Author(s):  
Cindy Lee Van Dover ◽  
Ete Z. Szuts ◽  
Steven C. Chamberlain ◽  
J. R. Cann
Keyword(s):  
Hydrothermal Vents ◽  
Mid Atlantic Ridge
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