Origin of Group 1A kimberlites: Fluid-saturated melting experiments at 45–55 kbar

Melting phase relations of the Udachnaya-East Group-I kimberlite at 3.0–6.5 GPa: Experimental evidence for alkali-carbonatite composition of primary kimberlite melts and implications for mantle plumes

“…7). Since the melting phase relations is a function of volatile contents (Girnis et al, 1995(Girnis et al, , 2011, the observed mismatch may be related to On the other hand, CO 2 may have a pronounced effect on the melting phase relations assemblage in the kimberlitic systems (Girnis et al, 1995(Girnis et al, , 2011. The identical very low In section 4.5 we give further evidence for CO 2 degassing.…”

“…Therefore, the experimental determination of the P-T conditions at which the kimberlitic melt becomes saturated with mantle phases just below its liquidus provides information on the P-T conditions of the source region. This is the rationale of many previous experimental studies that have examined melting phase relations of kimberlite rocks (Eggler and Wendlandt, 1979;Edgar et al, 1988;Ringwood et al, 1992;Edgar and Charbonneau, 1993;Kesson et al, 1994;Girnis et al, 1995Girnis et al, , 2011Mitchell, 2004). …”

“…There also have been several previous high-pressure experimental studies of kimberlites (Eggler and Wendlandt, 1979;Edgar et al, 1988;Ringwood et al, 1992;Edgar and Charbonneau, 1993;Kesson et al, 1994;Girnis et al, 1995Girnis et al, , 2011Mitchell, 2004), but most of these were conducted on altered or simplified compositions (Table 1).…”

Fluid inclusions in diamonds from the Diavik mine, Canada and the evolution of diamond-forming fluids

“…Price et al (2000) and Le Roex et al (2003) argue that CO 2 loss is minimal. Alternatively, Brey et al (1991) and Girnis et al (1995Girnis et al ( , 2005 advocate the formation of kimberlites as saturated melts that degas at sub-crustal pressures. Similarly, Salvioli-Mariani et al (2004) show a CO 2 release from lamproitic magmas at shallow pressures.…”

Evolution of the South African mantle—a case study of garnet peridotites from the Finsch diamond mine (Kaapvaal craton); Part 2: Multiple depletion and re-enrichment processes

“…Orthopyroxene growth and fluid/melt metasomatism may, however go together, when the precipitation of orthopyroxene from percolating silico-carbonatic-kimberlitic melts is considered. Such melts are generated by partial melting in carbonated peridotites as shown by a number of experimental studies (Brey et al, 2009;Dalton and Presnall, 1998;Girnis et al, 1995Girnis et al, , 2011Keshav et al, 2005). Kimberlitic melts are saturated in olivine, orthopyroxene, (±clinopyroxene) and garnet in their source region, but the role of olivine as a liquidus phase is suppressed at high pressures in kimberlitic melts with high CO 2 /H 2 O ratios (Girnis et al, 2011).…”