Formation of large sulfide mineral deposits along fast spreading ridges. Example from off-axial deposits at 12°43′N on the East Pacific Rise

Fouquet, Yves; Knott, R.; Cambon, Pierre; Fallick, Anthony E.; Rickard, David; Desbruyères, Daniel

doi:10.1016/0012-821x(96)00142-2

Cited by 69 publications

(29 citation statements)

References 25 publications

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“…4a). These low-temperature off-axis discharge zones have been discussed and described from various sites on the seafloor (Baker and Massoth 1987;Cowen et al 1990;Rona et al 1990;Fouquet et al 1996;Kelley et al 2001;Von Damm 2001;Kelley et al 2005;Davis et al 2009) and suggested by other modeling studies (e.g., Cathles 1993;Fisher et al 1994;Snelgrove and Forster 1996;Garrido and Machetel 2000). Elevated temperatures recorded around the top of faults 2 and 8 are due to early fluid discharge prior to the onset of significant hydrothermal fluid convection in the central model section, since these faults eventually act as recharge zones (see Fig.…”

Section: Heat and Fluid Flowmentioning

confidence: 88%

Hydrothermal fluid migration and brine pool formation in the Red Sea: the Atlantis II Deep

Schardt

2015

Miner Deposita

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Numerical heat and fluid flow simulations of the Atlantis II Deep in the Red Sea were conducted to investigate the development, migration, and discharge of hydrothermal fluids into a submarine depression and determine the conditions necessary to form a brine pool. High-salinity fluids are predicted to form by leaching Miocene evaporates, migrate and convect within young oceanic crust, and discharge onto the seafloor. Predicted fluid discharge temperatures (T max , 301°C), discharge fluid velocities (V max , 0.09 m/s), and salinities (S max , 21 wt%) increase over time and reach values comparable to modern seafloor observations. Established convection patterns and discharge behavior are robust and are not greatly affected by geometry of rock property changes. Modeling results were used to calculate the minimum conditions for hydrothermal fluids from a developing hydrothermal system to mix with seawater, reverse buoyancy, and begin to form a brine pool in a submarine depression. Under conditions encountered on the seafloor (T, 25-300°C; S, 5-25 wt%), fluid mixtures predicted to pond on the seafloor range from late in the mixing process (99 %) at low temperatures (T, 26°C) to much earlier (36 % mixing) at higher temperatures (T, 94°C). A model of brine pool evolution is proposed that describes the processes and conditions necessary to initiate brine pool formation and compares formation conditions with accumulated ore material in the Atlantis II Deep and other locations.

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Section: Heat and Fluid Flowmentioning

confidence: 88%

Hydrothermal fluid migration and brine pool formation in the Red Sea: the Atlantis II Deep

Schardt

2015

Miner Deposita

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“…Hydrothermal vent fluids for seafloor sulfide-sulfate mineralization typically have δ 34 S values of H 2 S that range from 1.5‰ to 7‰ (e.g., Shanks et al, 1995), which fall between the δ 34 S values for basalts (+0.1 ± 0.5‰) and seawater (+21‰). Therefore, the sulfur isotopic compositions of seafloor sulfide deposits can be used as evidence for the source of sulfur (e.g., Fouquet et al, 1996). On the MAR, the LHF is hosted by variable mixtures of serpentinized peridotite and mafic material (Delacour et al, 2008).…”

Section: Sulfur Sourcesmentioning

confidence: 99%

“…It is also unlikely that kinetic isotopic effects played an important role in the variation of δ 34 S values of vent fluids and hydrothermal sulfides . Therefore, the variation in sulfur isotopic compositions of hydrothermal sulfides might be due to changes in the end-member fluid composition, in-situ sulfate reduction, or local disequilibrium sulfur isotopic fractionation during sulfide deposition (Fouquet et al, 1996). In addition, the δ 34 S values of sulfides essentially reflect the isotope fractionation factor between sulfate (SO 4 ) and sulfide (H 2 S) (Ohmoto et al, 1983;Ohmoto and Goldhaber, 1997), and the isotope fractionation factors between SO 4 and H 2 S are 21‰ and 15‰ at 300 and 400 °C, respectively (Ohmoto and Lasaga, 1982).…”

Section: Introductionmentioning

confidence: 99%

Sulfur and lead isotopic compositions of massive sulfides from deep-sea hydrothermal systems: Implications for ore genesis and fluid circulation

Zeng

Chen

et al. 2017

Ore Geology Reviews

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“…By far, sample collection by submersibles at this site have exceeded the original collection by >100 times. Now, most hydrothermal activities occur in three structural environments: (1) axial graben, (2) graben faults, and (3) an off-axis segment [7] . At the off-axis segment, three hydrothermal sulfide sites have been discovered on the western side, at the top of the marginal high, and on the southern flank of the SE seamount.…”

Section: Geological Settingmentioning

confidence: 99%

“…The second step is composed of inactive chimneys up to 50 cm high and collapsed sulfides; the surface is covered by thin crusts of manganese oxide. At the top of the mound is a forest of several tens of chimneys and spires a few meters to 12 m high, where a low-temperature diffusing fluid is emitted through a small chimney; anemones, crabs, and fish are live around the vent [7] .…”

Section: Geological Settingmentioning

confidence: 99%

Formation of Fe-oxyhydroxides from the East Pacific Rise near latitude 13°N: Evidence from mineralogical and geochemical data

Zeng

Wang

Zhang

et al. 2008

Sci. China Ser. D-Earth Sci.

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The mineralogical and geochemical characteristics of Fe-oxyhydroxide samples from one dredge station (long. 103°54.48′W, lat. 12°42.30′N, water depth 2655 m) on the East Pacific Rise near lat 13°N were analyzed by XRD, ICP-AES, and ICP-MS. Most Fe-oxyhydroxides are amorphous, with a few sphalerite microlites. In comparison with Fe-oxyhydroxides from other fields, the variable ranges in the chemical composition of Fe-oxyhydroxide samples are very narrow; their Fe, Si, and Mn contents were 39.90%, 8.92%, and 1.59%, respectively; they have high Cu (0.88%-1.85%) and Co (65×10 −6 -704×10 −6 ) contents, and contain Co+Cu+Zn+Ni> 1.01%. The trace-element (As, Co, Ni, Cu, Zn, Ba, Sr) and major-element (Fe, Ca, Al, Mg) contents of these samples are in the range of hydrothermal sulfide from the East Pacific Rise near 13°N, reflecting that this type of Fe-oxyhydroxide constitutes a secondary oxidation product of hydrothermal sulfide. The Fe-oxyhydroxide samples from one dredge station on the East Pacific Rise near 13°N are lower in ΣREE (5.44×10 −6 -17.01×10 −6 ), with a distinct negative Ce anomaly (0.12-0.28). The Fe-oxyhydroxide samples have similar chondrite-normalized rare-earth-element (REE) patterns to that of seawater, and they are very different from the REE composition characteristics of hydrothermal plume particles and hydrothermal fluids, showing that the REEs of Fe-oxyhydroxide are a major constituent of seawater and that the Fe-oxyhydroxides can become a sink of REE from seawater. The quick settling of hydrothermal plume particles resulted in the lower REE content and higher Mn content of these Fe-oxyhydroxides, which are captured in part of the V and P from seawater by adsorption. The Fe-oxyhydroxides from one dredge station on the East Pacific Rise near 13°N were formed by secondary oxidation in a low temperature, oxygenated environment. In comparison with the elemental (Zn, Cd, Pb, Fe, Co, Cu) average content of hydrothermal sulfide samples from the East Pacific Rise near 13°N, the Zn, Cd, and Pb contents of the Fe-oxyhydroxides are lower, and their Fe, Co, and Cu contents are higher.

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Formation of large sulfide mineral deposits along fast spreading ridges. Example from off-axial deposits at 12°43′N on the East Pacific Rise

Cited by 69 publications

References 25 publications

Hydrothermal fluid migration and brine pool formation in the Red Sea: the Atlantis II Deep

Hydrothermal fluid migration and brine pool formation in the Red Sea: the Atlantis II Deep

Sulfur and lead isotopic compositions of massive sulfides from deep-sea hydrothermal systems: Implications for ore genesis and fluid circulation

Formation of Fe-oxyhydroxides from the East Pacific Rise near latitude 13°N: Evidence from mineralogical and geochemical data

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