## 5 Discussion  
### Genetic Implications for Vanadium and Cobalt Occurrence in the SAM  
The origin of the Fe-Ti-V oxide mineralization hosted by Proterozoic massf-type anorthosite has been explained through different processes, such as fractional crystallization [44; 45; 46], magma mixing [47], immiscibility between silicate and oxide magmas [48], stress-driven melt segregation [49], solid-state remobilization [50; 51], and hydrothermal remobilization [52]. For the Fe-Ti-V mineralization in the SAM, it was suggested that oxide-silicate melt moved from the deeper parts into the faulted zones of the anorthosite intrusion [16; 23]. Moreover, magnetite-ilmenite melt with sulphides followed the same route due to activity of convection flow [29; 46]. The Fe-Ti-oxide and sulphide mineralization in SAM was formed from a common parental magma through separate processes [16; 53]. In bulk-rock samples, the mean arithmetic content of vanadium and cobalt was 960 ppm (0.17 V\({}_{2}\)O\({}_{5}\)) and 122 ppm, respectively. The dominant ore minerals were magnetite, ilmenite and Al-spinels with subordinate quantities (1-3% of rock volume) of pyrrhotite (c.a. 80% of total sulphides) and pentlandite and chalcopyrite. These ore minerals were formed in the magmatic stage. The early-magmatic stage included the main concentrations of the oxide minerals of the titanomagnetite-ulvospinel-ilmenite series (in the temperature range of 575 \({}^{\circ}\)C-700 \({}^{\circ}\)C), and the late-magmatic stage included sulphides crystallizing at high temperatures (\(\sim\)600 \({}^{\circ}\)C), such as pyrrhotite, pentlandite, and chalcopyrite [26]. Various structures of ilmenite and spinel separation in magnetite were common, as well as the structures of these minerals, resulting from the decomposition of solid solutions during differentiation in the primary igneous associations during the change of PT conditions [23; 26; 27; 29; 41]. In the post-magmatic stage, in connection with the changes in the primary mineral composition, several processes were recognized, such as oxidation separation (temperature range 700 \({}^{\circ}\)C-400 \({}^{\circ}\)C); separation (500 \({}^{\circ}\)C-200 \({}^{\circ}\)C); and deuteric (400 \({}^{\circ}\)C), hydrothermal, and hypergenic transformations [23; 27; 29; 41]. Vanadium and cobalt have geochemically different characteristics. Vanadium has oxyphilic properties and has been found to be concentrated during the initial stage of crystallization of metallic minerals in magma. Cobalt is sulphophilic and it crystallizes with other Fe, Cu, and Ni sulphides in the later stages of magma differentiation. However, in our bulk-rock geochemical study, cobalt showed a good correlation with vanadium, Fe\({}_{2}\)O\({}_{3}\)t, and nickel (\(r\) = \(\sim\)0.70) and a weaker correlation with TiO\({}_{2}\) (\(r\) = 0.60). This indicates not only that there was a close spatial coexistence of magnetite-ilmenite mineralization, but also a common source of metals related to the differentiation of anorthosite-norite magma in the AMCG. Based on the EPMA results, the contents of vanadium in magnetite, ilmenite, and Al-spinels were highly variable. Magnetite, on average, contained 0.42 wt% V (0.75 V\({}_{2}\)O\({}_{5}\)). With progressive oxidation and recrystallization, vanadium moved gradually into magnetite. Vanadium was an isomorphic admixture in magnetite, substituting for Fe\({}^{+3}\) in its crystal lattice. The vanadium content varied slightly in magnetite, in contrast to the variable Ti content which was a substitution for Fe\({}^{+2}\). Vanadium had a weak positive correlation with Ti and Cr in the magnetite (Figure 14C,D). The redistribution of V and Fe\({}^{3+}\) substitution ions occurred under variable PT conditions during the evolution of the anorthosite massif [24; 44]. Ilmenite contained 0.14 wt% V on average (0.25 V\({}_{2}\)O\({}_{5}\)).