Melting of K-rich carbonated peridotite at 6–10GPa and the stability of K-phases in the upper mantle

Ancient mantle metasomatism recorded in subcalcic garnet xenocrysts: Temporal links between mantle metasomatism, diamond growth and crustal tectonomagmatism

“…K-Mg-carbonates in peridotites (e.g. Brey et al, 2011). These carbonates are presumably also high in Rb and their 87 Sr/ 86 Sr ratios will therefore grow very fast.…”

Solidus of alkaline carbonatite in the deep mantle

“…Carbonatite melt is considered a major metasomatic agent in the upper mantle, as revealed by studies of mantle xenoliths and alkaline volcanic rocks (e.g., Hauri et al, 1993;Yaxley et al, 1998) and high-pressure experiments on carbonated systems Dalton and Presnall, 1998;Dasgupta et al, 2004;Dasgupta and Hirschmann, 2006;Brey et al, 2008Brey et al, , 2011Ghosh et al, 2009;Grassi and Schmidt, 2011). Near-solidus melts of carbonated peridotite and eclogite systems, containing minor amounts of Na and K, show strong enrichments in alkalies.…”

The K₂CO₃ fusion curve revisited: New experiments at pressures up to 12 GPa

“…Mantle carbonatite melts with high-alkali contents have been reported by the studies of inclusions in fibrous diamonds (Navon, 1991;Sobolev et al, 1998;Zedgenizov et al, 2004;Hwang et al, 2006;Tomlinson et al, 2006;Klein-BenDavid et al, 2007). High pressure experiments on the partial melting of lithospheric mantle and subducted rocks indicate that near solidus melts of carbonated peridotite (Ghosh et al, 2009;Brey et al, 2011), carbonated eclogite (Dasgupta et al 2004;Yaxley and Brey 2004;Litasov and Ohtani, 2010;Kiseeva et al, 2013), and carbonated pelite Schmidt, 2011a, 2011b) show strong alkali enrichment. Chemical analyses of erupted products from Oldoinyo Lengai volcano also show high alkali content at 15-19 wt% and 4-5 wt% for Na 2 O and K 2 O, respectively (Keller et al, 2010).…”

“…Minor amounts of K 2 O in the lithospheric mantle and subducted rocks can cause appreciable decreases in their solidus temperatures of 300°C at 10 GPa for carbonated peridotites (Brey et al, 2011), 50-150°C at 3-5 GPa for eclogites (Spandler et al, 2008), and 100-300°C at 8 and 13 GPa for carbonated pelites (Grassi and Schmidt, 2011a). In addition, the high conductivities of carbonate melt containing alkalis in the asthenosphere are suggested to be responsible for the presence of low velocity zones (LVZ) at the top of the 410 km discontinuity (Gaillard et al, 2008;Sifre and Gaillard, 2012).…”

“…As the first melt formed from carbonated mantle (Dalton and Presnall, 1998;Dasgupta et al, 2004;Brey et al, 2011;Grassi and Schmidt, 2011a), carbonatite melt is considered as an efficient agent for mantle metasomatism owing to its high reactivity, high mobility, and high concentrations of incompatible trace elements (e.g., Green and Wallace, 1988;Dalton and Wood, 1993;Yaxley et al, 1998). Minor amounts of K 2 O in the lithospheric mantle and subducted rocks can cause appreciable decreases in their solidus temperatures of 300°C at 10 GPa for carbonated peridotites (Brey et al, 2011), 50-150°C at 3-5 GPa for eclogites (Spandler et al, 2008), and 100-300°C at 8 and 13 GPa for carbonated pelites (Grassi and Schmidt, 2011a).…”