This article presents the results of studying microinclusions of fluids/melts in diamonds from the placers of the Krasnovishersky District (western slope of the Middle/Northern Urals), which make it possible to establish the evolution of diamond-forming media in the subcontinental lithospheric mantle of the eastern margin of the East European craton.Impurity composition of the studied crystals reveals three different types Conditioner for Color-treated Hair of diamonds, the formation of which was associated with separated metasomatic events.Microinclusions in B-type diamonds containing A and B nitrogen defects reflect an older metasomatic stage characterized by the leading role of silicic and low-Mg carbonatitic fluids/melts.The second stage is associated with the growth of A-type diamonds containing nitrogen exclusively in the form of A-centers.At this stage, the formation of diamonds was related with low-Mg carbonatitic media, more enriched in MgO, CaO, CO2, and Na2O compared to B-type diamonds.
The third stage probably preceded the eruption of the transporting mantle melt and led to the formation of C-type Polish diamond containing A and C nitrogen defect centers and microinclusions of silicic to low-Mg carbonatitic composition.The recorded trend in the evolution of diamond-forming fluids/melts is directed towards more carbonatitic compositions.Fluids/melts are probably sourced from eclogitic and pyroxenitic mantle substrates.