Experimental constraints on majorite stability in the Earth's interior
Final Report Abstract
The main aim of this study was to experimentally investigate the stability of majorite garnets in depleted mantle compositions and to develop a new geobarometer for majorite garnets. To address these objectives we addressed the aforementioned issues: We successfully performed high-pressure experiments and some additional calibration runs in the Münster multi anvil apparatus, we investigated the stability of majorite garnets at different pressures, temperatures, and chemical compositions, and developed a new geobarometer that links chemical composition of majoritic garnet with pressure. The experimental results together with the new geobarometer will enable refined geobarometry of majoritic garnets found as inclusions in diamonds or in high-pressure rocks. As we experienced a major breakdown of our multi anvil apparatus, during which it was not operational for more than six months, we also conducted two minor experimental studies in depleted bulk compositions at atmospheric pressure. The first study focussed on the effects of Cr on trace element partitioning between spinel and silicate melts. In the other minor project we measured new thermodynamic properties of the Cr-endmember garnet knorringite.
Publications
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(2014). Thermodynamic and magnetic properties of knorringite garnet (Mg3Cr2Si3O12) based on low-temperature calorimetry and magnetic susceptibility measurements. Physics and Chemistry of Minerals, 41, 341-346
Wijbrans CH, Niehaus O, Rohrbach A, Pöttgen R, Klemme S
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(2015). Experimental determination of trace element partition coefficients between spinel and silicate melt: The influence of chemical composition and oxygen fugacity. Contributions to Mineralogy and Petrology, 69, 45-77
Wijbrans CH, Klemme S, Berndt J, Vollmer C
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(2016) An experimental investigation of the stability of majoritic garnet in the Earth’s mantle and an improved majorite geobarometer, Contributions to Mineralogy and Petrology, (2016) 171: 50
Wijbrans CH, Rohrbach A., Klemme S.
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(2016) The effect of chromium on the chemical and physical properties of spinel and garnet, and the stability of majorite garnet. Dissertationsschrift, Westfälische Wilhelms Universität Münster
Clazina H. Wijbrans
