Distribution of trace elements during breakdown of mantle garnet: an examplefrom Zabargad

Unusual amounts of trace elements were shown by ion probe investigations of Al-Di pyroxenites from the Zabargad peridotite of Italy. This characteristic, not exhibited by pyroxenes in spinel websterite, indicates the presence of a precursor or mantle garnet and emphasizes the importance of metamorphic processes in the redistribution of trace elements through mantle upwelling. Thestudy also shows that the Zabargad peridotite had been formed prior to lithospheric rifting and thinning of the area.