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Halogens in the Earth's mantle: Concentrations in nominally halogen-free mantle minerals and element partitioning during partial melting

Fachliche Zuordnung Mineralogie, Petrologie und Geochemie
Förderung Förderung von 2012 bis 2016
Projektkennung Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 225102979
 
Erstellungsjahr 2017

Zusammenfassung der Projektergebnisse

The main aim of this study was to experimentally investigate the influence of halogens on processes in the Earth’s mantle. To address these objectives we addressed the aforementioned issues: We investigated the storage capacity of F in nominally F-free mantle minerals at different pressures, temperatures, and chemical compositions. Our data show that olivine and pyroxene can store several thousands µg/g F, and several µg/g Cl. We compare our results with previous results on water storage and find the nominally halogen-free minerals can store the entire budget of halogens in the mantle. Furthermore, we performed experiments to study the stability of F-rich clinohumites in subduction zones. Our data show that F-rich humite-group minerals are much more stable than their water-bearing counterparts and this makes clinohumite very effective transport phases that could transport both water and halogens into the deeper mantle. Furthermore, a third set of experiments investigates the influence of F and the stability of wadsleyite and ringwoodite in the transition zone of the mantle at 410-660 km depths. Our data show that F has profound influence on the upper limit of the transition zone and F in the system destabilizes wadsleyite and shifts the upper boundary to higher pressure. In addition, we performed a set of experiments to study the partitioning of F between nominally halogen free mantle minerals (olivine, pyroxene, garnet) and silicate melts.

Projektbezogene Publikationen (Auswahl)

 
 

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