Effects of Substrate Composition and Subsurface Fluid Pathways on the Geochemistry of Seafloor Hydrothermal Deposits at the Lucky Strike Vent Field, Mid‐Atlantic Ridge

Sánchez‐Mora, Dennis; Jamieson, John; Cannat, Mathilde; Escartı́n, J.; Barreyre, Thibaut

doi:10.1029/2021gc010073

Cited by 7 publications

(3 citation statements)

References 103 publications

(244 reference statements)

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“…This and the overall low δ 15 N (− 4.70 to 9.11‰) allows discarding a depth/location effect on a putative increase in photosynthetic organic matter suggesting instead chemosynthetic pathways. Methanotrophy instead of thiotrophy may lead to more positive δ 34 S values 73 and Capelinhos fluids are naturally enriched in 34 S, reflecting contrasting subseafloor fluid/rock interactions compared to the other LS edifices 74 . Thus, we suggest the more positive δ 34 S values at Capelinhos are driven by methanotrophy and geological processes influencing fluid composition.…”

Section: Discussionmentioning

confidence: 99%

Fluid chemistry alters faunal trophodynamics but not composition on the deep-sea Capelinhos hydrothermal edifice (Lucky Strike vent field, Mid-Atlantic Ridge)

Alfaro-Lucas,

Martin,

Michel

et al. 2024

Sci Rep

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The recently discovered deep-sea Capelinhos hydrothermal edifice, ~ 1.5 km of the main Lucky Strike (LS) vent field (northern Mid-Atlantic Ridge), contrasts with the other LS edifices in having poorly-altered end-member hydrothermal fluids with low pH and chlorine, and high metal concentrations. Capelinhos unique chemistry and location offer the opportunity to test the effects of local abiotic filters on faunal community structure while avoiding the often-correlated influence of dispersal limitation and depth. In this paper, we characterize for the first time the distribution patterns of the Capelinhos faunal communities, and analyze the benthic invertebrates (> 250 µm) inhabiting diffusive-flow areas and their trophic structures (δ13C, δ15N and δ34S). We hypothesized that faunal communities would differ from those of the nearest LS vent edifices, showing an impoverished species subset due to the potential toxicity of the chemical environment. Conversely, our results show that: (1) community distribution resembles that of other LS edifices, with assemblages visually dominated by shrimps (close to high-temperature focused-fluid areas) and mussels (at low-temperature diffuse flow areas); (2) most species from diffuse flow areas are well-known LS inhabitants, including the bed-forming and chemosymbiotic mussel Bathymodiolus azoricus and (3) communities are as diverse as those of the most diverse LS edifices. On the contrary, stable isotopes suggest different trophodynamics at Capelinhos. The high δ15N and, especially, δ13C and δ34S values suggest an important role of methane oxidation (i.e., methanotrophy), rather than the sulfide oxidation (i.e., thiotrophy) that predominates at most LS edifices. Our results indicate that Capelinhos shows unique environmental conditions, trophic structure and trophodynamics, yet similar fauna, compared to other LS edifices, which suggest a great environmental and trophic plasticity of the vent faunal communities at the LS.

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Section: Discussionmentioning

confidence: 99%

Fluid chemistry alters faunal trophodynamics but not composition on the deep-sea Capelinhos hydrothermal edifice (Lucky Strike vent field, Mid-Atlantic Ridge)

Alfaro-Lucas,

Martin,

Michel

et al. 2024

Sci Rep

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“…The LSHF comprises at least 18 vent sites (Barreyre et al., 2012; Charlou et al., 2000; Escartin et al., 2015; Von Damm et al., 1998), each associated with a sulfide mound, bearing several focused vents (smokers) and surrounded by a semi‐elliptical domain of diffuse venting. Radium‐226/Ba dating of hydrothermal barite indicates that hydrothermal venting at Lucky Strike is at least 6,600 years old and the oldest sulfide deposits at Tour Eiffel are at least 3,800 years old (Sánchez‐Mora et al., 2022). The heat source for hydrothermal circulation, with an estimated energy flux of 200–1,000 MW (Barreyre et al., 2012), is most likely an axial melt lens 3.5–4 km beneath the seafloor (Combier et al., 2015; Crawford et al., 2010; Singh et al., 2006).…”

Section: Geological Contextmentioning

confidence: 99%

Diffuse Venting and Near Seafloor Hydrothermal Circulation at the Lucky Strike Vent Field, Mid‐Atlantic Ridge

Wheeler,

Cannat,

Chavagnac

et al. 2024

Geochem Geophys Geosyst

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We report on a 3 years monitoring experiment of low to medium temperature diffuse venting at two vent sites (Tour Eiffel and White Castle) of the Lucky Strike, black smoker‐type hydrothermal field, Mid‐Atlantic Ridge. Diffuse vents account for a large part of the energy flux of mid‐ocean ridges hydrothermal fields and provide key habitats for the hydrothermal fauna. We document the time and space variability of diffuse venting temperature and chemistry, describe the effect of tidal loading and currents and discuss the extent of mixing, cooling of black smoker fluids, heating of entrained seawater and anhydrite precipitation/dissolution in the substratum. We emphasize the role of a thin (<2 m) volcaniclastic formation capping the brecciated basalt substratum. This formation is porous, but becomes impermeable when indurated by hydrothermal precipitates. It forms an intermediate layer between the vents at the seabed and the fluids as they discharge out of the brecciated basalts. Diffuse fluids inferred to discharge out of meter‐spaced cracks in the brecciated basalts beneath this volcaniclastic layer are hot (>80°C) and contain >10% of the hot endmember fluid component, over distances of up to 25 m from the black smokers. These results provide a geologically integrated framework in which to study site‐scale, near seafloor hydrothermal circulation and associated vent habitats at Lucky Strike and other black smoker‐type hydrothermal fields. They suggest diffuse heat fluxes in the upper range of previously published estimates at the two studied Lucky Strike hydrothermal vent sites.

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“…The oldest known vent fields along the MAR with ages of >100 Ka (e.g., Peterburgskoe, Pobeda, Semenov 4, Krasnov, TAG) are typically characterized by pyrite-rich mounds with diameters greater than 100 m that require prolonged periods of venting to form (Cherkashov et al, 2010(Cherkashov et al, , 2017Jamieson et al, 2014;Kuznetsov et al, 2011;Lalou et al, 1990). By contrast, the relatively small size and close spacing of the hydrothermal edifices at Fåvne are similar to those of relatively young (<10 Ka) MOR-hosted vent fields, such as Lucky Strike (MAR) or Endeavor (Juan de Fuca Ridge; Jamieson et al, 2013;Sánchez-Mora et al, 2022).…”

Section: Secondary Replacement Of Sulfide Mineralsmentioning

confidence: 99%

Iron Oxyhydroxide‐Rich Hydrothermal Deposits at the High‐Temperature Fåvne Vent Field, Mohns Ridge

Gini,

Jamieson,

Reeves

et al. 2024

Geochem Geophys Geosyst

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The recently discovered Fåvne vent field, located at 3,040 m depth on the slow‐spreading Mohns mid‐ocean ridge between Greenland and Norway, is a high‐temperature (≥250°C) vent field that is characterized by Fe oxyhydroxide‐rich and S‐poor chimneys and mounds. The vent field is located on both the hanging wall and footwall of a normal fault with a ∼1.5 km throw that forms the western edge of the ∼20 km wide ridge axial valley. Data collected during exploration of the site using a remotely operated vehicle as well as mineralogical and geochemical analyses of rock samples and sediments are used to characterize the geological setting of the vent field and composition of the hydrothermal deposits. The chimney walls are highly porous and lack defined chalcopyrite lined conduits, typical of high‐temperature chimneys. Overall, abundant Fe oxyhydroxide precipitation at high‐temperature vents at Fåvne reflects an excess of Fe over reduced S in the fluid, leading to precipitation of Fe oxide and oxyhydroxide minerals at high to moderate temperature vents (>100°C), and as microbially mediated and abiotic precipitation of Fe oxyhydroxide minerals at low‐temperature diffuse vents (<100°C). The mounds and chimneys exhibit low base metal and reduced S concentrations relative to globally averaged seafloor deposits and suggest subseafloor mixing of hydrothermal fluid with seawater, causing metal sulfide precipitation. Cobalt enrichment at Fåvne may reflect a subsurface influence of an ultramafic substrate on circulating fluids, although ultramafic rocks are absent on the seafloor and no other elements typical of ultramafic deposits are present.

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Effects of Substrate Composition and Subsurface Fluid Pathways on the Geochemistry of Seafloor Hydrothermal Deposits at the Lucky Strike Vent Field, Mid‐Atlantic Ridge

Cited by 7 publications

References 103 publications

Fluid chemistry alters faunal trophodynamics but not composition on the deep-sea Capelinhos hydrothermal edifice (Lucky Strike vent field, Mid-Atlantic Ridge)

Fluid chemistry alters faunal trophodynamics but not composition on the deep-sea Capelinhos hydrothermal edifice (Lucky Strike vent field, Mid-Atlantic Ridge)

Diffuse Venting and Near Seafloor Hydrothermal Circulation at the Lucky Strike Vent Field, Mid‐Atlantic Ridge

Iron Oxyhydroxide‐Rich Hydrothermal Deposits at the High‐Temperature Fåvne Vent Field, Mohns Ridge

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