Geochemistry and origin of the Mirny field kimberlites, Siberia

Diamond preservation in the lithospheric mantle recorded by olivine in kimberlites

“…Previous work has also shown that the composition of olivine is directly correlated with the mineralogy of kimberlites, with lower-Mg# olivine occurring in kimberlites that are enriched in Fe-Ti oxide minerals 36 . These combined observations explain why high diamond grades are associated with kimberlite rocks containing high concentrations of Mg and low contents of Ti ( [3][4][5] ). This suggests that bulk kimberlite compositions could also be used to evaluate diamond potential, provided that the effects of crustal contamination and hydrothermal alteration are taken into account 51,52 .…”

“…This notion has led to the widely held view that the composition of kimberlites has no relationship to their diamond cargo 2 . However, a few studies [3][4][5] have suggested a potential link between kimberlite chemistry and diamond grade (i.e., concentration).…”

“…Here we explore a complementary approach that examines the diamond tenor in kimberlites by tracking conditions that result in diamond dissolution in the lithospheric mantle. This strategy builds on empirical observations that certain compositional features, such as elevated Ti, Zr and Y concentrations in garnet and high Fe 3+ in ilmenite recovered from kimberlites, which are attributed to intense melt metasomatism and increasing oxygen fugacity in the lithospheric mantle, are commonly associated with poor diamond preservation and low diamond grades 2,3,10,13,15,16 . However, the exact cause of the correlation between low diamond preservation and "Ti-rich" melt metasomatism is unclear, as is the composition and origin of the melt(s) involved, the timing of metasomatism, and their potential relationship to kimberlite magmatism.…”

Botuobinskite and mirnyite, two new minerals of the crichtonite group included in Cr-pyrope xenocrysts from the Internatsionalnaya kimberlite

“…The Mirny kimberlite field comprises seven diamondiferous kimberlite pipes (Internatsionalnaya, Mir, Sputnik, Amakinskaya, 23rd Party Congress, Dachnaya and Taezhnaya), emplaced in the middle Palaeozoic at ~360 Ma (Sobolev et al , 1997; Kiselev et al , 2014; Malkovets et al , 2016; Skuzovatov et al , 2016; Agashev et al , 2018). This area represents a stable ancient craton core featuring a thick diamondiferous keel (Griffin et al , 1999a).…”