The Archean komatiite-hosted, PGE-bearing Ni–Cu sulfide deposit at Vaara, eastern Finland: evidence for assimilation of external sulfur and post-depositional desulfurization

Synthesis of the Geological Evolution and Metallogeny of Finland

“…Unlike in some other Archean greenstone belts, such as the Kalgoorlie terrane in Western Australia, only a few occurrences of komatiite-hosted Ni-Cu sulfides have been discovered in the Finnish greenstone belts (Konnunaho et al, 2015). 2.3), postmagmatic alteration has upgraded the metal content of the sulfide fraction (Konnunaho et al, 2013), which enhances the potential of their exploitation. 2.3) in northwestern Finland.…”

“…Many reasons have been suggested for the scarcity of significant komatiitic Ni-Cu deposits in Finland (Konnunaho et al, 2013;Maier et al, 2013): the parental magma of the Finnish komatiites was more differentiated and cooler than the most ore-producing komatiites elsewhere, and dynamic lava channel environments where significant amounts of sulfide-bearing substrate could be assimilated were uncommon. Also, the total volume of the mafic-ultramafic magmatism was small compared to Western Australia or Canada, and the small size or absence of VMS and other sulfidic deposits restricts the amount of potential sources of external sulfur (cf.…”

Magmatic controls on the genesis of Ni–Cu±(PGE) sulphide mineralisation on Mars

“…Gorbachev and Kashirceva, 1986;Liu et al, 2007;Song et al, 2003) and, most importantly, assimilation of crustal sulphur by devolatilisation, partial melting or bulk assimilation of sulphide/ sulphate bearing country rocks (e.g. Bekker et al, 2009;Fiorentini et al, 2012;Konnunaho et al, 2013;Lesher and Campbell, 1993;Ripley and Al-Jassar, 1987;Li, 2003, 2013;Ripley et al, 1999) 3. Martian magmatism 3.1.…”

Geochemistry of komatiites and basalts in Archean greenstone belts of Russian Karelia with emphasis on platinum-group elements

“…The Alexo, Texmont, and Hart sulfide deposits in the Abitibi greenstone belt have also been regarded as results of sulfide immiscibility triggered by assimilation of sulfidic sedimentary rocks (Lahaye et al 2001). In the Karelia craton, Konnunaho et al (2013) presented multiple sulfur isotope evidence that the komatiites related to the Vaara Ni deposit in the Suomussalmi greenstone belt have assimilated external sulfur. Archean sulfide-bearing BIF have been reported to be present in the Ilomantsi and Kostomuksha greenstone belts (Sorjonen-Ward et al and Luukkonen 2005;Kuleshevich and Gor'kovets 2008), which could potentially have provided external sulfur to the komatiites to form sulfide deposits.…”