Anomalously high concentrations of metals in fluid of the Semenov modern hydrothermal system (Mid-Atlantic Ridge, 13°31′ N): LA-ICP-MS study of fluid inclusions in minerals

Бортников, Н. С.; Симонов, В. А.; Amplieva, E. E.; Боровиков, А. А.

doi:10.1134/s1028334x14060221

Cited by 10 publications

(6 citation statements)

References 8 publications

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“…NaCl). This range is comparable to ranges of salinity (and Th) measured in fluid inclusions (Figure 8a) in rocks associated with hydrothermal fields both of mafic (TAG: Petersen et al, 1998;MARK: Delaney et al, 1987;Saccocia & Gillis, 1995) and ultramafic nature (Rainbow, Logatchev, Ashadze, Semenov, Irinovskoe; Bortnikov et al, 2011Bortnikov et al, , 2014Bortnikov et al, , 2015Simonov et al, 2015). Fluid inclusions from the highly silicified sample ODM218 display a large salinity range (2.1-10 wt.% eq.…”

Section: Insights From Fluid Inclusion Salinity: Phase Separationsupporting

confidence: 78%

“…NaCl; Figure 8a). (Delaney et al, 1987;Saccocia & Gillis, 1995) and TAG (Petersen et al, 1998), detachment plane (ultra)mafic rocks hosting hydrothermal vents (Rainbow, Logatchev, Ashadze, Semenov, Irinovskoe; Bortnikov et al, 2011Bortnikov et al, , 2014Bortnikov et al, , 2015Simonov et al, 2015); (b) Heterogeneity of inclusion Th and salinity at the quartz grain scale for the primary inclusions only, for clarity issues, using a similar color and symbol for inclusions in each grain. Highly silicified mafic breccias (ODM155 and ODM218) present higher homogenization temperatures (180°C-350°C) than moderately silicified ones, either mafic (ODM195) or mixed mafic-ultramafic (ODM173; 150°C-220°C; Figure 8a; Table 3).…”

Section: Microthermometrymentioning

confidence: 99%

“…Figure 8. Homogenization temperatures (Th) against salinity for (a) all primary and secondary fluid inclusions; data are compared to Th and salinity ranges measured in fluid inclusions from oceanic gabbros (MARK:Kelley & Delaney, 1987), diabases (Atlantis Massif: Castelain et al, 2014), mafic silicified breccias from MARK(Delaney et al, 1987;Saccocia & Gillis, 1995) and TAG(Petersen et al, 1998), detachment plane (ultra)mafic rocks hosting hydrothermal vents (Rainbow, Logatchev, Ashadze, Semenov, Irinovskoe;Bortnikov et al, 2011Bortnikov et al, , 2014Bortnikov et al, , 2015Simonov et al, 2015); (b) Heterogeneity of inclusion Th and salinity at the quartz grain scale for the primary inclusions only, for clarity issues, using a similar color and symbol for inclusions in each grain. Seawater salinity is indicated with a blue line.…”

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confidence: 99%

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Fluid Circulation Along an Oceanic Detachment Fault: Insights From Fluid Inclusions in Silicified Brecciated Fault Rocks (Mid‐Atlantic Ridge at 13°20′N)

Verlaguet

Bonnemains

Mével

et al. 2021

Geochem Geophys Geosyst

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The MAR 13°20′N corrugated detachment fault is composed of pervasively silicified mafic cataclastic breccias, instead of ultramafics and gabbros commonly found at other detachments. These breccias record overplating of hangingwall diabases, with syntectonic silicification due to important influx of silica‐iron‐rich fluids, able to leach alkalis and calcium. Fluids trapped in quartz inclusions show important salinity variations (2.1–10 wt.% NaCl eq.) indicating supercritical phase separation. Fluid inclusions also contain minor amounts of H2 ± CO2 ± CH4 ± H2S, with high H2/CO2 and H2/H2S ratios, signatures typical of ultramafic‐hosted vent fluids. We propose that seawater infiltrated the hangingwall upper crust at the axis adjacent to the active detachment, reaching a reaction zone at the dyke complex base (∼2 km). At >500°C, fluids become Si‐rich during diabase alteration (amphibolite‐facies alteration in clasts), and undergo phase separation. Brines, preferentially released in the nearby detachment fault during diabase brecciation, mix with serpentinite‐derived fluids bearing H2 and CH4. Cooling during detachment deformation and fluid upward migration triggers silica precipitation at greenschist‐facies conditions (quartz + Fe‐rich‐chlorite ± pyrite). Important variations in fluid inclusion salinity and gas composition at both sample and grain scales record heterogeneous fluid circulation at small spatial and short temporal scales. This heterogeneous fluid circulation operating at <2 km depth, extending both along‐axis and over time, is inconsistent with models of fluids channeled along detachments from heat sources at the base of the crust at the fault root. Present‐day venting at detachment footwall, including Irinovskoe, is instead likely underlain by fluid circulation within the footwall, with outflow crossing the inactive detachment fault near‐surface.

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Section: Insights From Fluid Inclusion Salinity: Phase Separationsupporting

confidence: 78%

Section: Microthermometrymentioning

confidence: 99%

mentioning

confidence: 99%

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Fluid Circulation Along an Oceanic Detachment Fault: Insights From Fluid Inclusions in Silicified Brecciated Fault Rocks (Mid‐Atlantic Ridge at 13°20′N)

Verlaguet

Bonnemains

Mével

et al. 2021

Geochem Geophys Geosyst

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“…In particular, in hydrothermal fluids that formed the volcanogenic massive sulfide (VMS) deposits the chloride concentration ranged from few to 20 wt % NaCl equiv (e.g., Large; Simonov et al; Vikent’ev et al; , Karpukhina et al). Similar concentrations of chloride salts, with the average value of 4–8 wt % NaCl equiv and maximum concentration up to 26 wt % NaCl equiv, were established in hydrothermal vent fluids of black smokersmodern analogues of VMS deposits. − High-salinity (>30 wt % NaCl equiv) hydrogen-bearing brines were formed as a result of serpentinization of mantle harzburgite at the Mid-Atlantic Ridge at temperatures close to 500 °C . Similar processes resulted in the formation of Co-rich Au-bearing VMS deposits hosted in the ultramafic rocks of paleo-island arc structures within the Main Uralian Suture (Fault) .…”

Section: Introductionmentioning

confidence: 60%

Gold Transport in Hydrothermal Chloride-Bearing Fluids: Insights from in Situ X-ray Absorption Spectroscopy and ab Initio Molecular Dynamics

Тагиров

Trigub

Filimonova

et al. 2018

ACS Earth Space Chem.

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Chloride-bearing fluids are widespread in the Earth’s interior from low-temperature subsurface conditions to deep lithosphere. The concentration of chloride salts varies from diluted aqueous solutions to concentrated brines and anhydrous (dry) chloride melts beneath volcanoes. Here we report an investigation of the state of Au in hydrothermal chloride fluids and anhydrous melts by means of in situ X-ray absorption spectroscopy combined with ab initio molecular dynamics simulations and thermodynamic modeling. The experiments included registration of Au L3-edge X-ray absorption near edge structure/extended X-ray absorption fine structure spectra of Au-bearing fluids in the temperature range from 350 to 575 °C at pressures of 150–4500 bar. Spectra of Au dissolved in dry CsCl/NaCl/KCl + K2S2O8 melt were recorded at 650 °C. It was found that Au is coordinated by two Cl atoms (R Au–Cl = 2.25–2.28 Å). The alkali metal atoms (Me) were detected in the distant coordination sphere of Au at R Au‑Me = 3.3–4.1 Å. The alkali metal cations in the vicinity of Au–Cl complex partly compensate the positive charge located on Au and, by this way, affect the Au–Cl distance. An increase of the fluid pressure causes expansion of the second coordination sphere composed of the alkali metal cations, which leads to the increase of the positive Au charge and results in slight contraction of the first coordination sphere of Au. Accordingly, the transport of Au in high-temperature chloride-bearing natural ore-forming fluids of moderate to high densities (>0.3 g·cm–3) can be explicitly described by the formation of the AuCl2 – at any salt concentration from low-salinity fluids to hydrosaline liquids and anhydrous melts. In general, this means that the hydrothermal fluid chemistry simplifies with increasing temperature.

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“…Early surveys carried out during Russian cruises located and defined several extinct hydrothermal fields throughout the 13°30′N detachment using a deep‐towed self‐potential system, in addition to TV‐camera surveys and sampling [ Bortnikov et al ., ; Cherkashev et al ., ; Cherkashov et al ., ; Pertsev et al ., ]. These data and results clearly demonstrate that hydrothermal activity has been present in space and time throughout the exposed fault surface, from its termination near the ridge axis to the limit of the corrugated surface to the west.…”

Section: Geological Setting and Prior Workmentioning

confidence: 99%

Tectonic structure, evolution, and the nature of oceanic core complexes and their detachment fault zones (13°20′N and 13°30′N, Mid Atlantic Ridge)

Escartı́n

Mével

Petersen

et al. 2017

Geochem Geophys Geosyst

107

179

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Microbathymetry data, in situ observations, and sampling along the 13°20′N and 13°20′N oceanic core complexes (OCCs) reveal mechanisms of detachment fault denudation at the seafloor, links between tectonic extension and mass wasting, and expose the nature of corrugations, ubiquitous at OCCs. In the initial stages of detachment faulting and high‐angle fault, scarps show extensive mass wasting that reduces their slope. Flexural rotation further lowers scarp slope, hinders mass wasting, resulting in morphologically complex chaotic terrain between the breakaway and the denuded corrugated surface. Extension and drag along the fault plane uplifts a wedge of hangingwall material (apron). The detachment surface emerges along a continuous moat that sheds rocks and covers it with unconsolidated rubble, while local slumping emplaces rubble ridges overlying corrugations. The detachment fault zone is a set of anostomosed slip planes, elongated in the along‐extension direction. Slip planes bind fault rock bodies defining the corrugations observed in microbathymetry and sonar. Fault planes with extension‐parallel stria are exposed along corrugation flanks, where the rubble cover is shed. Detachment fault rocks are primarily basalt fault breccia at 13°20′N OCC, and gabbro and peridotite at 13°30′N, demonstrating that brittle strain localization in shallow lithosphere form corrugations, regardless of lithologies in the detachment zone. Finally, faulting and volcanism dismember the 13°30′N OCC, with widespread present and past hydrothermal activity (Semenov fields), while the Irinovskoe hydrothermal field at the 13°20′N core complex suggests a magmatic source within the footwall. These results confirm the ubiquitous relationship between hydrothermal activity and oceanic detachment formation and evolution.

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Anomalously high concentrations of metals in fluid of the Semenov modern hydrothermal system (Mid-Atlantic Ridge, 13°31′ N): LA-ICP-MS study of fluid inclusions in minerals

Cited by 10 publications

References 8 publications

Fluid Circulation Along an Oceanic Detachment Fault: Insights From Fluid Inclusions in Silicified Brecciated Fault Rocks (Mid‐Atlantic Ridge at 13°20′N)

Fluid Circulation Along an Oceanic Detachment Fault: Insights From Fluid Inclusions in Silicified Brecciated Fault Rocks (Mid‐Atlantic Ridge at 13°20′N)

Gold Transport in Hydrothermal Chloride-Bearing Fluids: Insights from in Situ X-ray Absorption Spectroscopy and ab Initio Molecular Dynamics

Tectonic structure, evolution, and the nature of oceanic core complexes and their detachment fault zones (13°20′N and 13°30′N, Mid Atlantic Ridge)

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