Sulfide mineralization in an ultramafic-rock hosted seafloor hydrothermal system: From serpentinization to the formation of Cu–Zn–(Co)-rich massive sulfides

Zn-, Mn- and Co-rich chromian spinels from the Bou-Azzer mining district (Morocco): Constraints on their relationship with the mineralizing process

“…In addition, reported mineral assemblages in serpentinites and sediments collected close to vents from hydrothermal fields occurring along the MAR and other hydrothermal systems worldwide Bougault et al, 1998;Dias and Barriga, 2006;Usui et al, 2007) have very high proportions of Mn oxyhydroxides. Marques et al (2007) also showed that all chromian spinel grains exhibit alteration halos along fractures and rims of ferrian chromite, which are rimmed by minor amounts of magnetite, lesser chlorite and other phyllosilicates. The composition of these chromian spinel grains varied widely, even within the same rock sample: Cr# = 0.41-0.65 and Mg# = 0.38-0.67, which ferrian chromite rims display the highest contents in Mn and Zn (up to 4.9 wt.% MnO and 1.11 wt.% ZnO).…”

“…The temperature of these vent fluids reaches 400°C , with the highest concentrations of Fe, Mn, Cu, Zn, Co and Ni ever reported for MAR and is considered a modern analogue for the formation of ancient mafic-hosted VMS deposits (e.g. Douville et al, 2002;Von Damm et al, 2003;Marques et al, 2007;Petersen et al, 2009). In addition, reported mineral assemblages in serpentinites and sediments collected close to vents from hydrothermal fields occurring along the MAR and other hydrothermal systems worldwide Bougault et al, 1998;Dias and Barriga, 2006;Usui et al, 2007) have very high proportions of Mn oxyhydroxides.…”

“…The recent discovery of modern seafloor hydrothermal systems hosted by serpentinized peridotites (Fouquet and IRIS Scientific Party, 2001;Barriga et al, 2003;Dias and Barriga, 2006;Marques et al, 2007) in slow to ultra-slow spreading ridges have provided new insights into the hydrothermal alteration of chromian spinels. Marques et al (2007) analysed 65 chromian spinel crystals from samples collected at 2300 m depth from the ultramafic rock-hosted Rainbow hydrothermal vent field, located at 36°14′N-33°53′W on the Mid-Atlantic Ridge (MAR).…”

“…Marques et al (2007) analysed 65 chromian spinel crystals from samples collected at 2300 m depth from the ultramafic rock-hosted Rainbow hydrothermal vent field, located at 36°14′N-33°53′W on the Mid-Atlantic Ridge (MAR). The temperature of these vent fluids reaches 400°C , with the highest concentrations of Fe, Mn, Cu, Zn, Co and Ni ever reported for MAR and is considered a modern analogue for the formation of ancient mafic-hosted VMS deposits (e.g.…”

Chimneys in Paleozoic massive sulfide mounds of the Urals VMS deposits: Mineral and trace element comparison with modern black, grey, white and clear smokers

“…The outer part is partly replaced by bornite, whilst the inner part of zone B contains Y-phase Cu 2 Fe 3 S 5 (Borodaev et al, 2004;Mozgova et al, 2008). Diverse Co-Ni-As-Te-Au rare mineral assemblages (Table 4) occur in assemblage with bornite veinlets in chalcopyrite (Mozgova et al, 1996(Mozgova et al, , 2008Vikentyev et al, 2000;Lein et al, 2003;Bortnikov et al, 2004;Bortnikov and Vikentyev, 2005;Marques et al, 2007;Fouquet et al, 2010;Bogdanov et al, 2015). Sphalerite and pyrrhotite crystals are abundant in the outer and inner walls of clear smokers (Fig.…”