Interaction of Titanium Minerals and Their Melts with Diamond-Forming Media (Experiments at 7–8 GPa)

• Published in: Geochemistry international Vol. 56; no. 2; pp. 148 - 161
• Main Authors: Litvin, Yu. A., Bovkun, A. V., Garanin, V. K.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.02.2018; Springer; Springer Nature B.V
• Subjects: Analysis; Calcium titanate; Carbon; Carbonates; Diamond mining; Diamonds; Earth; Earth and Environmental Science; Earth Sciences; Eclogite; Ferroalloys; Forming; Geochemistry; Ilmenite; Immiscibility; Iron; Kimberlite; Mantle; Melts; Minerals; Peridotite; Perovskite; Rutile; Silicates; Solubility; Titanium; Titanium dioxide; Upper mantle; titanium concentration and diamond content in kimberlite; diamond genesis; liquid immiscibility; titanium minerals; melts of titanium minerals; solubility; carbonatite melts; physicochemical experiment
• ISSN: 0016-7029; 1556-1968
• DOI: 10.1134/S0016702918010032

Melting relations in the multicomponent diamond-forming systems of the upper mantle with a boundary of K–Na–Mg–Fe–Ca carbonate, phases of the model peridotite and eclogite, carbon, and titanium minerals from kimberlite (ilmenite FeTiO 3 , perovskite CaTiO 3 , and rutile TiO 2 ) were studied experimentally at 7–8 GPa and 1600–1650°C. Perovskite reacts with the formation of rutile in the diamond-forming silicate–carbonate melts. We discovered liquid immiscibility between melts of titanium minerals, on the one hand, and carbonate–carbon, peridotite–carbonate–carbon, and eclogite–carbonate–carbon diamond-forming melts, on the other. The solubility of titanium mineral in diamond-forming melts is negligible independent of their concentration in the experimental systems. Growth melts retain high diamond-forming efficiency. In general, the experimental results are evident for the xenogenic nature of titanium minerals in inclusions in diamond and, therefore, in diamond-forming melts. It is shown that the physicochemical factors that may correlate the diamond content with the concentration of Ti in kimberlite do not occur during the diamond genesis in silicate–carbonate–carbon parental melts containing titanium minerals and their melts.