Towards a new model for kimberlite petrogenesis: Evidence from unaltered kimberlites and mantle minerals

Chlorine in mantle-derived carbonatite melts revealed by halite in the St.-Honoré intrusion (Québec, Canada)

“…Second, Cl-bearing primary carbonatite magmas imply Cl --bearing carbonated mantle sources, suggesting that chlorine is more abundant in the source mantle than currently thought. This is consistent with chlorine-and alkali-rich compositions of minerals and fluid and/or melt inclusions in mantle xenoliths and kimberlites (e.g., Giuliani et al, 2012;Kamenetsky et al, 2014), and with suggestions that an alkalichloride component is critical in the formation of diamond in carbonate melts (Palyanov et al, 2007;Tomlinson et al, 2004). Third, chlorine reduces mantle solidus temperatures (Litasov et al, 2013;Safonov et al, 2007), potentially allowing carbonatite and carbonate-silicate melts to form at lower temperature.…”

Carbonate–silicate liquid immiscibility in the mantle propels kimberlite magma ascent

“…Kjarsgaard et al, 2009). This paradox can be partially rectified by demonstrating inevitable Naloss during alteration of kimberlites and recognising Narich carbonate compositions of melt inclusions in minerals of kimberlites (Kamenetsky et al, 2009b(Kamenetsky et al, , 2013(Kamenetsky et al, , 2014 and kimberlite-hosted mantle xenoliths Korsakov et al, 2009;Giuliani et al, 2012;Sharygin et al, 2013;Kamenetsky et al, 2014).…”

“…Ubiquitous olivine in kimberlites, responsible for the previously inferred ultramafic composition of parental melts, has been demonstrated to largely (>50%) represent the lithospheric mantle invaded by an essentially carbonatite liquid Brett et al, 2009;Patterson et al, 2009;Arndt et al, 2010;Pilbeam et al, 2013). The aluminosilicate-poor, Na-Ca carbonate composition of the kimberlite parental melt was suggested by compositions of melt inclusions entrapped in olivine, Cr-spinel and ilmenite from kimberlites in Siberia, Canada, South Africa and Greenland (see review in Kamenetsky et al, 2014). Additionally, carefully designed experimental studies of a putative primary kimberlite (e.g.…”

“…An essentially carbonatite melt, parental to most kimberlites (e.g. Kamenetsky et al, 2007Kamenetsky et al, , 2008Kamenetsky et al, , 2014, is undersaturated in silica and thus capable of dissolving mantle silicates, especially orthopyroxene, the most Si-rich mantle mineral, abundant in the mantle and absent in kimberlite rocks (e.g. Mitchell, 1973).…”

Diamond crystallization in a CO 2 -rich alkaline carbonate melt with a nitrogen additive

“…Among other potential media of the natural diamond formation, ultra alkaline carbonate-fluid systems where growth occurs at the minimal P and T parameters are of special interest [1]. In addition, a number of recent works have proven the important role of both alkaline carbonate melts in the generation of proto-kimberlite melts [2][3][4][5] and carbon dioxide as the most important mantle fluid component in oxidized domains [6]. The possibility of diamond crystallization in the presence of carbon dioxide is also supported by detection of inclusions containing carbonate [7][8][9] and CO 2 fluid [10] in natural diamonds.…”