Mineralogy and geochemistry of hydrothermal precipitates from Kairei hydrothermal field, Central Indian Ridge

Wang, Yejian; Han, Xiqiu; Petersen, Sven; Jin, Xiaofeng; Qiu, Zhongyan; Zhu, Jinghan

doi:10.1016/j.margeo.2014.05.003

Cited by 43 publications

(43 citation statements)

References 44 publications

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“…The low Cu1Zn average of the BVF sulfides is comparable to mafic hosted systems (supporting information [Fouquet et al, 2010]. Au/Ag ratios are substantially higher than mafic systems and amongst the average values of ultramafic-hosted systems, with only Logatchev being higher [Fouquet et al, 2010;Wang et al, 2014]. The low Ni, high Sn and high Au are comparable to the Kairei system, where some portion of the basement was inferred to be ultramafic [Wang et al, 2014].…”

Section: Geochemistrymentioning

confidence: 90%

“…However, Sn concentrations are intermediate between mafic‐ and ultramafic‐hosted vents, as is the Zn/Cd ratio of 379, compared to 304 for the average of MORB sites and 614 for the average of ultramafic‐hosted sites [ Fouquet et al ., ]. Au/Ag ratios are substantially higher than mafic systems and amongst the average values of ultramafic‐hosted systems, with only Logatchev being higher [ Fouquet et al ., ; Wang et al ., ]. The low Ni, high Sn and high Au are comparable to the Kairei system, where some portion of the basement was inferred to be ultramafic [ Wang et al ., ].…”

Section: Discussionmentioning

confidence: 99%

“…Au/Ag ratios are substantially higher than mafic systems and amongst the average values of ultramafic‐hosted systems, with only Logatchev being higher [ Fouquet et al ., ; Wang et al ., ]. The low Ni, high Sn and high Au are comparable to the Kairei system, where some portion of the basement was inferred to be ultramafic [ Wang et al ., ]. We suggest the presence of ultramafic lithologies to some degree is likely, given the exceptionally thin basaltic crust, the depth of hydrothermal circulation, ultra‐slow spreading rate and high H 2 content of the fluids.…”

Section: Discussionmentioning

confidence: 99%

“…The BVF fulfils none of these associations yet is auriferous. However, there is growing evidence that vent sites situated on slow‐spreading mid‐ocean ridges, especially those ultramafic hosted, are particularly gold‐rich [ Münch et al ., 2001; Tao et al ., ; Nayak et al ., ; Fouquet et al ., ; Wang et al ., ]. In this geotectonic setting, we suggest the availability of gold‐rich sulfide blebs in the reaction zone and, vitally, the precipitation of gold in beehive chimney structures has enabled the formation of an auriferous sea floor massive sulfide deposit.…”

Section: Discussionmentioning

confidence: 99%

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Geology, sulfide geochemistry and supercritical venting at the Beebe Hydrothermal Vent Field, Cayman Trough

Webber

Roberts

Murton

et al. 2015

Geochem Geophys Geosyst

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The Beebe Vent Field (BVF) is the world's deepest known hydrothermal system, at 4960 m below sea level. Located on the Mid-Cayman Spreading Centre, Caribbean, the BVF hosts high temperature ( 4018C) ''black smoker'' vents that build Cu, Zn and Au-rich sulfide mounds and chimneys. The BVF is highly gold-rich, with Au values up to 93 ppm and an average Au:Ag ratio of 0.15. Gold precipitation is directly associated with diffuse flow through ''beehive'' chimneys. Significant mass-wasting of sulfide material at the BVF, accompanied by changes in metal content, results in metaliferous talus and sediment deposits. Situated on very thin (2-3 km thick) oceanic crust, at an ultraslow spreading centre, the hydrothermal system circulates fluids to a depth of 1.8 km in a basement that is likely to include a mixture of both mafic and ultramafic lithologies. We suggest hydrothermal interaction with chalcophile-bearing sulfides in the mantle rocks, together with precipitation of Au in beehive chimney structures, has resulted in the formation of a Au-rich volcanogenic massive sulfide (VMS) deposit. With its spatial distribution of deposit materials and metal contents, the BVF represents a modern day analogue for basalt hosted, Au-rich VMS systems.

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Section: Geochemistrymentioning

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Geology, sulfide geochemistry and supercritical venting at the Beebe Hydrothermal Vent Field, Cayman Trough

Webber

Roberts

Murton

et al. 2015

Geochem Geophys Geosyst

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“…Despite this, the data for global VMS deposits show that a larger proportion of mafic‐hosted systems are auriferous compared to either bi‐modal mafic or felsic host‐rock types (Table ), although only 11 of the 69 mafic‐hosted deposits are recognized as being mid‐ocean ridge deposits. On the seafloor, there is growing evidence that vent sites situated on ultraslow spreading and ultramafic crust are particularly gold‐rich [ Munch et al ., ; Tao et al ., ; Nayak et al ., ; Fouquet et al ., ; Wang et al ., ]. The mid‐Cayman spreading center is ultraslow spreading, with one of the lowest melt thicknesses in the world [ Klein and Langmuir , ; White et al ., ] producing an extremely thin mafic crust just a few hundred meters thick [ Stroup and Fox , ; ten Brink et al ., ].…”

Section: Discussionmentioning

confidence: 99%

The formation of gold‐rich seafloor sulfide deposits: Evidence from the Beebe hydrothermal vent field, Cayman Trough

Webber

Roberts

Murton

et al. 2017

Geochem Geophys Geosyst

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The Beebe vent field (BVF) in the Cayman Trough has built an auriferous massive sulfide deposit on the ultraslow spreading mid‐Cayman spreading center. The genesis of auriferous sulfide deposits at mid‐ocean ridges is not fully understood, although there is a growing recognition that slow and ultraslow spreading centers are conducive to gold mineralization. Analysis of hydrothermal precipitates from the BVF indicates that the highest gold contents are present within “beehive diffusers,” which have developed a highly porous pyrrhotite framework. The beehive structure allows vent fluids to effuse slowly while allowing ingress of seawater to cool the fluid. The prevalence of pyrrhotite in the beehive samples, lack of sulfates, association between pyrrhotite and gold grains, and results of thermodynamic modeling suggest gold precipitation occurred under highly reduced conditions even during mixing with seawater. In contrast, high‐temperature chimneys, with a single orifice, maintain high temperatures to the primary vent orifice and much of the gold is lost to seawater. Despite this, both chimney types are relatively gold‐enriched, which points to a further underlying cause for high gold at the BVF such as interaction of hydrothermal fluids with ultramafic lithologies in the basement. The final gold composition of the deposit is partially controlled by loss of gold during mass‐wasting of the material, with gold depletion most prevalent in blocks formed at beehive‐type chimneys. The BVF demonstrates that the overall gold content of a massive sulfide deposit is the sum of basement, precipitation, and surface processes.

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Sulfur sources for ultramafic‐hosted sulfide mineralization in the Tianzuo hydrothermal field, 63.5° E, South‐west Indian Ridge: Insights from sulfur and carbon isotopes

et al. 2022

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To date, discovered ultramafic-hosted seafloor massive sulfide (UM-SMS) deposits are rare, remain poorly understood in terms of their genesis, and typically form along slow-and ultraslow-spreading mid-oceanic ridges. The Tianzuo hydrothermal field (THF) is the only UM-SMS deposit identified so far along the ultraslow-spreading South-west Indian Ridge (SWIR). This study presents new detailed mineralogical and S-C isotopic data for serpentinized peridotite, gabbro, serpentinite, and sulfide ore samples from the THF and to provide new insights into the processes that formed the deposit. Chromium-reduced sulfur (CRS) and sulfate-sulfur (SS) in samples of serpentinized peridotite have positive δ 34 S values (up to 10.22‰ and 20.67‰, respectively). The CRS formed through thermochemical reduction of seawater sulfate during reactions between seawater and ultramafic rocks, whereas the SS most likely occurred as dissolved sulfate phases in seawater occupying the pore space of serpentinized peridotite after exposure at the seafloor. The serpentinite samples contain SS with δ 34 S values of 19.21‰-20.9‰, indicating infiltration by seawater that led to the deposition of seawater sulfate. The sulfide ores have acid-volatile sulfur (AVS), CRS, and SS δ 34 S values of 10.99‰-12.07‰, 2.34‰-10.98‰, and À4.13‰ to 2.76‰, respectively, indicating that the AVS and CRS within the samples are dominated by sulfur reduced from seawater sulfate (e.g., anhydrite) and leached from the surrounding wall rocks, although the re-oxidization of microbial-reduced sulfur most likely generated the sulfate with low and negative δ 34 S values. The total carbon and total organic carbon δ 13 C values of the THF samples are negative and range from À21.99‰ to À0.34‰ and À26.7‰ to À21.02‰, respectively, further suggesting that the samples record microbial activity. Gabbro samples have strongly negative AVS (À10.69‰) and CRS (À7.2‰) δ 34 S values, indicating that microbial-reduced sulfur derived from shallow levels in the crust was incorporated into the hydrothermal system that circulated through the deeper-seated gabbroic units. Our results suggest

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Mineralogy and geochemistry of hydrothermal precipitates from Kairei hydrothermal field, Central Indian Ridge

Cited by 43 publications

References 44 publications

Geology, sulfide geochemistry and supercritical venting at the Beebe Hydrothermal Vent Field, Cayman Trough

Geology, sulfide geochemistry and supercritical venting at the Beebe Hydrothermal Vent Field, Cayman Trough

The formation of gold‐rich seafloor sulfide deposits: Evidence from the Beebe hydrothermal vent field, Cayman Trough

Sulfur sources for ultramafic‐hosted sulfide mineralization in the Tianzuo hydrothermal field, 63.5° E, South‐west Indian Ridge: Insights from sulfur and carbon isotopes

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