Influence of mantle CO2 in the generation of carbonatites and kimberlites

  title={Influence of mantle CO2 in the generation of carbonatites and kimberlites},
  author={Peter John Wyllie and Wuu-Liang Huang},
THE explanation of why partial fusion of mantle peridotite sometimes yields basalts, sometimes kimberlites and sometimes carbonatites is given by the phase relationships in the system CaO–MgO–SiO2–CO2. The key is the intersection of a sub-solidus carbonation reaction with the solidus, which introduces carbonates as primary minerals alongside silicates on the surface of the liquidus. 
Links between Carbonatite and Kimberlite Melts in Chloride–Carbonate–Silicate Systems: Experiments and Application to Natural Assemblages
Recent data suggest an active role for chloride-bearing alkali carbonatitic melts in the formation and evolution of kimberlites, whereas experiments indicate that chlorides could be responsible for
Orthopyroxene survival in deep carbonatite melts: implications for kimberlites
Kimberlites are rare diamond-bearing volcanic rocks that originate as melts in the Earth’s mantle. The original composition of kimberlitic melt is poorly constrained because of mantle and crustal
Peridotite–CO2–H2O, and carbonatitic liquids in the upper asthenosphere
THE recent discovery that CO2 at upper mantle pressures has a dramatic effect on the melting temperature of peridotite (because the silicate assemblage becomes carbonated), and on the composition of
Mantle carbonatite eruptions: Crustal context and implications
Abstract High level carbonatites in south-east Zambia have sub-volcanic intrusion sequences similar to those of the classic Chilwa complex, with the significant addition of magnesiocarbonatite
Carbon, carbides, carbonates and carbonatitic melts in the Earth's interior
  • V. Stagno
  • Geology
    Journal of the Geological Society
  • 2019
Over recent decades, many experimental studies have focused on the effect of CO2 on phase equilibria and melting behaviour of synthetic eclogites and peridotites as a function of pressure and
Effect of variable carbonate concentration on the solidus of mantle peridotite
Abstract To explore the effect of variable CO2 concentrations on the solidus of natural carbonated peridotite, we determined near-solidus phase relations of three different nominally anhydrous,
Melting in the mantle in the presence of carbon: Review of experiments and discussion on the origin of carbonatites
Carbon emission at volcanic centers requires a constant balance between output (mostly by volcanism, either at plate boundaries or intraplate) and input (mostly at trench settings) of carbon from and
Petrogenetic grid for siliceous dolomites extended to mantle peridotite compositions and to conditions for magma generation
Decarbonation reactions in the system CaO-MgO-SiO_2-CO_2 involve calcite, dolomite, magnesite, and quartz, and the products enstatite, forsterite, diopside, and wollastonite, among others. Each
Solubility of CO2 in olivine melilitite at high pressures and role of CO2 in the earth's upper mantle
AbstractThe positions of the liquidi and the near-liquidus phases of olivine-melilitite+CO2 have been determined under MH-buffered and ‘furnace-buffered’ conditions up to 40 kb. It is found that CO2
The Transition from Carbonate to Silicate Melts in the CaO—MgO—SiO2—CO2 System
The compositions of melts in equilibrium with a lherzolite mineral INTRODUCTION assemblage were determined in the analogue system CaO– The common association of carbonatites with silicaMgO–SiO2–CO2


Experimental Evidence against the Role of Selective Volatilization on the Lunar Surface
IT has been suggested1 that the deduced sequence of crystallization and observed chemical zoning in plagioclase of a feldspar-rich lunar basalt (Fra Mauro 14310) provides evidence for selective
Low-Velocity Zone of the Earth's Mantle: Incipient Melting Caused by Water
Experimental phase diagrams for the systems gabbro-water and peridotite-water indicate that, if there is any water in the upper mantle, then traces of hydrous interstitial silicate magma will be
Eutectic between wollastonite II and calcite contrasted with thermal barrier in MgO-SiO2-CO2 at 30 kilobars, with applications to kimberlite-carbonatite petrogenesis
In the join CaCO_3-CaSiO_3 at 30 kbars, calcite melts at 1615°C, wollastonite II at 1600°C, and a binary eutectic occurs at 1365°C with liquid composition 43 wt.% CaCO_3, 57 wt.% CaSiO_3. The
Fluid Precipitates in Rocks from the Earth's Mantle
Xenoliths of rocks from the Earth9s mantle are commonly included in alkalic basalt and kimberlite diatremes. The xenoliths, many of them highly deformed by plastic flow, consist primarily of olivine
A CO2 Charged Asthenosphere
Solubility considerations lead to a model of the asthenosphere which contains a CO2-rich liquid phase. The model explains variations in the asthenosphere between ocean and shield areas.
Stability of Hornblende and a Model for the Low Velocity Zone
THERE have been many discussions, but few experiments, related to the occurrence and stability of hornblende in the upper mantle1–4. We have obtained evidence relating to hornblende stability in
Electron microprobe measurement of pyroxenes coexisting with H2O-undersaturated liquid in the join CaMgSi2O6-Mg2Si2O6-H2O at 30 kilobars, with applications to geothermometry
Mixtures of synthetic crystalline enstatite and diopside were reacted with small water contents in sealed capsules in piston-cylinder apparatus at 30 kb between 1000° C and 1700° C. The compositions
Subsolidus and melting relationships for calcite, magnesite and the join CaCO3-MgCO3 36 kb
Subsolidus and melting relations for the CaCO_3-MgCO_3 join at 30 kb have been determined using piston-cylinder apparatus. Data are also presented for the melting curve of CaCO_3 to 30 kb, the
The join Mg2Si2O6-CaMgSi2O6 at 30 kilobars pressure and its application to pyroxenes from kimberlites
At 30 kb pressure the join Mg2Si2O6-CaMgSi2O6 is binary. The liquidus descends in a smooth curve from the melting point of enstatite (1840°C) to that of diopside (1715°C). The solidus is intersected