Project Details
Projekt
Crystal chemistry of hibonite as indicator for oxygen fugacities during solar nebula condensation
Subject Area
Mineralogy, Petrology and Geochemistry
Term
from 2010 to 2014
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 145655517
Calcium-aluminium-rich inclusions (CAIs) yield the oldest measured ages of any solar system solid and as such can give essential information on the temperature and oxygen fugacity conditions of the early solar nebula. The mineral hibonite, present in several CAIs, is one of the primary condensates from the solar nebula and contains significant amounts of Ti in different redox states. It is therefore an ideal candidate for providing insight into the oxygen fugacity of the early solar system. Experiments conducted so far reveal that the oxidation state of Ti does not depend solely on the oxygen fugacity at which hibonite is forming, but also on its crystal-chemistry. Further syntheses of hibonites with different Ti, Mg and V contents at different temperatures and oxygen fugacities are therefore necessary to obtain an oxygen barometer for hibonite. Cation distribution in hibonite will be obtained by single-crystal structural refinements, whereas EELS spectra of synthetic hibonites will be carefully analysed in order to obtain information both on the Ti oxidation state and on its cation distribution. We expect that our study will be essential for constraining the complex history of condensation and alteration of meteoritic hibonites from different types of chondrites which will be also analysed using the same techniques.
DFG Programme
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