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Solidus of carbonated fertile peridotite under fluid-saturated conditions


Falloon, TJ and Green, DH, Solidus of carbonated fertile peridotite under fluid-saturated conditions, Geology (Boulder), 18 pp. 195-199. ISSN 0091-7613 (1990) [Refereed Article]

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Copyright 1990 Geological Society of America

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The solidus for a fertile peridotite composition ("Hawaiian pyrolite") in the presence of a CO2-H2O fluid phase has been determined from 10 to 35 kbar. The intersection of the decarbonation reaction (olivine + diopside + CO2 ←→ orthopyroxene + dolomite) with the pyrolite solidus defines the point Q′, located at 22 kbar and 940 C. At pressures less than Q′, the solidus passes through a temperature maximum at 14 kbar, 1060 C. The solidus is coincident with amphibole breakdown at pressures less than 16 kbar. At pressures above Q′, the solidus is defined by the dissolution of crystalline carbonate into a sodic, dolomitic carbonatite melt. The solidus is at a temperature of 925 C at ∼28 kbar. The solidus temperature above the point Q′ is similar to the solidus determined for Hawaiian pyrolite-H2O-CO2 for small contents of H2O (<0.3 wt%) and CO2 (<5 wt%), thus indicating that the primary sodic dolomitic carbonatite melt at both solidi has a very low and limited H2O solubility. The new data clarify the roles of carbonatite melt, carbonated silicate melt, and H2O-rich fluid in mantle conditions that are relatively oxidized (fO2 ∼ MW to FMQ). In particular, a carbonatite melt + garnet lherzolite region is intersected by continental shield geothermal gradients, but such geotherms only intersect regions with carbonated silicate melt if perturbed to higher temperatures ("kinked geotherm").

Item Details

Item Type:Refereed Article
Keywords:solidus fertile peridotite, hawaiian pyrolite, CO2-H2O fluid phase, carbonatite melt, geotherms
Research Division:Earth Sciences
Research Group:Geology
Research Field:Igneous and metamorphic petrology
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the earth sciences
UTAS Author:Falloon, TJ (Dr Trevor Falloon)
UTAS Author:Green, DH (Professor David Green)
ID Code:98804
Year Published:1990
Funding Support:Australian Research Council (88/18620)
Deposited By:Earth Sciences
Deposited On:2015-03-03
Last Modified:2015-04-16

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