The application of olivine geothermometry to infer crystallization temperatures of parental liquids: implications for the temperature of MORB magmas

• Published in: Chemical Geology
• Main Authors: Falloon, TJ, Danyushevsky, LV, Ariskin, A, Green, DH, Ford, CE
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier BV 2007
• Subjects: Earth Sciences; Geology; Igneous and Metamorphic Petrology; Craven; Iceland
• Online Access: https://doi.org/10.1016/j.chemgeo.2007.01.015; http://ecite.utas.edu.au/51597

We have performed a detailed evaluation of three olivine geothermometers for anhydrous systems representing three different approaches to modelling olivine-melt equilibrium. The Ford et al. [Ford, C. E., Russell, D. G., Craven, J.A., Fisk, M. R., 1983. Olivine-liquid equilibria: Temperature, pressure and composition dependence of the crystal/liquid cation partition coefficients for Mg, Fe2+, Ca and Mn. J. Petrol., 24, 256-265.] geothermometer describes olivine liquidus temperature as a function of melt composition and pressure, and the composition of the liquidus olivine as a function of melt composition, pressure and temperature. The Herzberg and O'Hara [Herzberg, C., O'Hara, M.J., 2002. Plume-associated ultramafic magmas of Phanerozoic Age. Journal of Petrology, 43, 1857-1883.] geothermometer describes olivine liquidus temperature similarly to Ford et al. [Ford, C. E., Russell, D. G., Craven, J.A., Fisk, M. R., 1983. Olivine-liquid equilibria: Temperature, pressure and composition dependence of the crystal/liquid cation partition coefficients for Mg, Fe2+, Ca and Mn. J. Petrol., 24, 256-265.], and olivine composition as function of melt composition only. The Putirka [Putirka, K.D., 2005. Mantle potential temperatures at Hawaii, Iceland, and the mid-ocean ridge system, as inferred from olivine phenocrysts: evidence for thermally driven mantle plumes, Geochem. Geophys. Geosyst., 6, Q05L08, doi:10.1029/2005GC000915.] geothermometer describes both olivine liquidus temperature and composition as function of melt composition only. A comparison of these three geothermometers with experimental data at 0.1MPa and 1.5GPa reveals that the Ford et al. [Ford, C. E., Russell, D. G., Craven, J.A., Fisk, M. R., 1983. Olivine-liquid equilibria: Temperature, pressure and composition dependence of the crystal/liquid cation partition coefficients for Mg, Fe2+, Ca and Mn. J. Petrol., 24, 256-265.] geothermometer is the most successful in reproducing experimental temperatures and olivine-melt K D's. We therefore recommend that the Ford et al. [Ford, C. E., Russell, D. G., Craven, J.A., Fisk, M. R., 1983. Olivine-liquid equilibria: Temperature, pressure and composition dependence of the crystal/liquid cation partition coefficients for Mg, Fe2+, Ca and Mn. J. Petrol., 24, 256-265.] olivine geothermometer be used in parental liquid calculations that involve the incremental addition of olivine to obtain equilibrium with a target olivine phenocryst composition at low pressure. The thermometer of Putirka [Putirka, K.D., 2005. Mantle potential temperatures at Hawaii, Iceland, and the mid-ocean ridge system, as inferred from olivine phenocrysts: evidence for thermally driven mantle plumes, Geochem. Geophys. Geosyst., 6, Q05L08, doi:10.1029/2005GC000915.] was found to systematically calculate anomalously high temperatures for high MgO experimental compositions at both 0.1MPa and 1.5GPa. The application of the Ford et al. [Ford, C. E., Russell, D. G., Craven, J.A., Fisk, M. R., 1983. Olivine-liquid equilibria: Temperature, pressure and composition dependence of the crystal/liquid cation partition coefficients for Mg, Fe2+, Ca and Mn. J. Petrol., 24, 256-265.] geothermometer to calculate the temperatures of crystallization for parental MORB liquids in mid-crustal magma chambers reveals that there is an 115C temperature range. The hottest MORB parental liquids have crystallisation temperatures of 1345C (MgO contents 16wt.%) for a mid-crustal pressure of 0.2Gpa. 2007 Elsevier B.V. All rights reserved.