Massive sulfides of Mount Jourdanne along the super-slow spreading Southwest Indian Ridge and their genesis

Nayak, Binod Bihari; Halbach, Peter; Pracejus, Bernhard; Münch, Ute

doi:10.1016/j.oregeorev.2014.05.004

Cited by 35 publications

(19 citation statements)

References 60 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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%

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

Webber

Roberts

Murton

et al. 2015

Geochem Geophys Geosyst

View full text Add to dashboard Cite

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.

show abstract

Section: Discussionmentioning

confidence: 99%

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

Webber

Roberts

Murton

et al. 2015

Geochem Geophys Geosyst

View full text Add to dashboard Cite

show abstract

“…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

View full text Add to dashboard Cite

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.

show abstract

“…In addition, pyrites tend to have more Pb enrichment at the Duanqiao field (up to 5320 ppm), whereas most Pb contents in pyrites from the Longqi field are near the ACTA GEOLOGICA SINICA (English Edition) http://www.geojournals.cn/dzxben/ch/index.aspx http://mc.manuscriptcentral.com/ags detection limit (Table 3). Previous studies have suggested that Pb is mainly derived from the destruction of surrounding rocks (e.g., feldspars) (Hannington et al, 1995(Hannington et al, , 2005, and the variations in the Pb concentrations in sulfide at the mid-ocean hydrothermal systems may reflect different water-rock interaction processes (Fouquet et al, 2010;Nayak et al, 2014). Recently, Ye Jun (2010) and Yang Weifang (2017) have reported the Pb contents and isotopic data of bulk sulfides from the two fields.…”

Section: Implications For Important Mineralization Processesmentioning

confidence: 99%

“…The mineral associations of the sulfide deposit at the midocean ridges are dominantly controlled by basement rock compositions, although fluid chemistry and complexation also affect the mineralogy. The mineralogical features of sulfide deposit vary widely between basaltic, ultramafic, and sedimentary environments at mid-ocean ridges (Zierenberg et al, 1998;Fouquet et al, 2010;Nayak et al, 2014). Several studies have systematically modeled the sulfide and sulfate precipitation sequence from the hydrothermal fluids, whose results generally indicate that precipitation occurs in two groups: 1) an early hightemperature chalcopyrite, pyrrhotite, and anhydrite group followed by 2) a later lower temperature sphalerite and pyrite group (Haymon et al, 1983;Janecky and Seyfried, 1984;Hannington et al, 1995;Wang et al, 2017).…”

mentioning

confidence: 99%

Mineralogy and Chemistry of Sulfides from the Longqi and Duanqiao Hydrothermal Fields in the Southwest Indian Ridge

Zhang

Hou

et al. 2018

Acta Geologica Sinica (Eng)

View full text Add to dashboard Cite

Recent investigations found that hydrothermal activity and sulfide mineralization occurs along the Southwest Indian Ridge (SWIR). The Longqi and Duanqiao hydrothermal fields between 49° E and 53° E of the SWIR are two prospective mineralization areas discovered by Chinese scientists. With the aim to determine the mineralogical and chemical characteristics of sulfide minerals, we have conducted detailed studies for samples from the two areas using an optical microscope, X‐ray diffractometer, scanning electron microscope, and electron microprobe. The mineralization processes in the Longqi area are divided into three main stages: (1) the low‐medium‐temperature stage: colloform pyrite (Py I) + marcasite → euhedral pyrite (Py II), (2) the high‐temperature stage: isocubanite (±exsolved chalcopyrite) + pyrrhotite → coarse‐grained chalcopyrite (Ccp I), and (3) the medium–low‐temperature stage: sphalerite + fine‐grained chalcopyrite inclusions (Ccp II) → aggregates of anhedral pyrite (Py III) ± marcasite → Fe‐oxide (‐hydroxide) + amorphous silica. The mineralization processes in the Duanqiao area are divided into two main stages: (1) the medium–high‐temperature stage: subhedral and euhedral pyrite (Py I′) → coarse‐grained chalcopyrite (Ccp I′) and (2) the medium–low‐temperature stage: sphalerite → fine‐grained chalcopyrite (Ccp II′) + chalcopyrite inclusions (Ccp II′) → silica‐cemented pyrite (Py II′) + marcasite → Fe‐oxide + amorphous silica. We suggest that the fine‐grained chalcopyrite inclusions in sphalerite from Longqi and Duanqiao were formed by co‐precipitation and replacement mechanisms, respectively. Primary sphalerites from both fields are enriched in Fe (avg. 5.84 wt% for the Longqi field vs. avg. 3.69 wt% for the Duanqiao field), Co (avg. 185.56 ppm for the Longqi field vs. 160.53 ppm for the Duanqiao field), and Cd (avg. 1950 ppm for the Longqi field vs. avg. 525.26 ppm for the Duanqiao field). Cu contents in pyrite from the Duanqiao field (Py I′: avg. 849.23 ppm and Py II′: avg. 1191.11 ppm) tend to be higher than those from the Longqi field (Py I: avg. 26.67 ppm, Py II: avg. 445 ppm, and Py III: avg. 179.29 ppm). Chalcopyrite from both fields is enriched in Zn (Ccp I: avg. 3226.67 ppm, Ccp II: avg. 9280 ppm, Ccp I′: avg. 848 ppm, Ccp II′ (inclusions): avg. 1098 ppm, and Ccp II′ (fine‐grained): avg. 1795 ppm). The varying contents of Zn in the different pyrite and chalcopyrite generations may result from the zone refining process. An integrated study of the mineralogy and mineralogical chemistry suggests that the hydrothermal fluids of the Longqi area are likely conditioned with higher temperatures and relatively lower fO2 and fS2 than those of the Duanqiao area, but in contrast to the former, the latter is much affected by the compositions of the surrounding rocks.

show abstract

Massive sulfides of Mount Jourdanne along the super-slow spreading Southwest Indian Ridge and their genesis

Cited by 35 publications

References 60 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

Mineralogy and Chemistry of Sulfides from the Longqi and Duanqiao Hydrothermal Fields in the Southwest Indian Ridge

Contact Info

Product

Resources

About