Diamond Synthesis from Graphite in the Presence of Water and SiO2: Implications for Diamond Formation in Quartzites from Kazakhstan

摘要: Recent studies of microdiamonds from orogenic belts related to continental collisions induced experimentalists explore new crystallization media possible for diamond synthesis. This has led considerable progress in diamond-synthesis experiments under high pressures and temperatures. Diamond was found grow a wide variety systems, which drastically differ the metal-solvent-catalyst that have been known since 1950s industrial syntheses. The newer systems include melts consisting silicate, carbonate, sulfur-carbon, as well carbon-oxygen-hydrogen (C-O-H) supercritical fluid presence different oxides. Our experimental program focused on compositionally approximating natural sites ultrahigh-pressure metamorphic rocks, where abundant occur. Yet be explored are SiO 2 -rich constitute an important diamond-bearing lithology world-famous Kokchetav (UHPM) terrane. purpose this study is determine what effect synthesis C-O-H fluid. Experiments performed Walker-style multianvil apparatus at T = 1450–1500°C P 8–8.5 GPa Si-C-O-H system levels oxygen fugacity ( f O ) us conclusion requires more reduced than its counterpart synthesized Mg-C-O-H Ca-Mg-C-O-H similar pressures, temperatures, times.