Interaction of Kimberlite Magma with Diamonds Upon Uplift from the Upper Mantle to the Earth’s CrustстатьяИсследовательская статья
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Дата последнего поиска статьи во внешних источниках: 6 декабря 2018 г.
Аннотация:Interaction between a melt of kimberlite from the Nyurbinskaya pipe (Yakutia) and natural
monocrystalline diamonds was studied experimentally at 0.15 GPa and 1200–1250°C in high-pressure and
high-temperature Ar gas “bombs.” The loss of diamond weight with slight surface dissolution of diamonds in a Ca carbonate-bearing kimberlite melt over the course of 2 h (the period of kimberlite transport from uppermantlediamond-forming chambers to the crustal cumulative centers) is 3–4.5%. In 4 and 7–8 days (underthe conditions of crustal cumulative centers), the weight of diamond decreases with remarkable bulk dissolutionby 13.5 and 24.5–27.5%, respectively. In the run at 0.15 GPa and 1200°C kimberlite and ilmenite (added)melts interact to produce perovskite melt. Both of the melts, rich in titanium minerals, are immiscible with kimberlite melt and therefore cannot influence the diamond dissolution kinetics in the kimberlite melt. The experimental results suggest that precisely the dissolution processes for thermodynamically metastable diamonds in silicate–carbonate kimberlitic magmas are responsible for the effective decrease in the diamond potential of kimberlite deposits. The paper discusses the physicochemical reasons for the decrease in the kimberlite
diamond potential during the chemically active history of diamond genesis: from upper-mantle chambers
to the explosive release of diamonds and kimberlite material from cumulative centers to the Earth’s surface. The data on experimental physicochemical studies of the origin, analytical mineralogy of inclusions,and isotope geochemistry of diamonds are correlated.