Unraveling Redox Conditions of Mantle Metasomatism: Insights from the Catoca mantle eclogites (Kasai Craton, Angola)

Mantle metasomatism has been defined as a process of alteration by means of a fluid/melt. This affects the chemistry of the original rock by either altering the initial mineral composition, or by creating new minerals. Within one mineral grain, it can be expressed in altered rims or proto-cores. Although mantle rocks experienced metasomatism were excessively studied, the redox conditions of mantle metasomatism are still poorly constrained. To explore the redox conditions of metasomatism in the Earth’s mantle, we plan to study mantle rocks that contain several generations of garnet. The garnet shows a complete transformation, including intermediate stages, from its original form to fully metasomatically altered, all due to a single metasomatic event. Previous studies have allowed us to track the chemical composition evolution over the metasomatic event. By using the Synchrotron Mössbauer Source spectroscopy, we can also track the evolution of the redox state.