Hi, I'm studying a rather peculiar mafic sample that contains a good amount of oxides (titanomagmetite mostly) but also some iron oxides that contain up to 4wt% NiO. The rest of the minerals are quite depleted in Ni. This is quite outside of my field. Which process can result in Ni-enrichment in iron oxides?
The high nickel contents indicate orthomagmatic, sulphide enrichment in the magmatic (mafic) host rock. In addition, in many mafic rocks, liquid segregation of a sulphide and oxide melt occurs, because of the capability of sulfide liquid to dissolve significant amounts of oxygen, leading to the crystallization of magnetite and incorporation of nickel from the sulphides. The amount of dissolved oxygen in a sulfide melt is dependent on the conditions and metal contents of the sulfide liquid. At very high nickel contents, another influencing factor is the degree of post-magmatic hydrothermal oxidation.
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