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Program Organizing committee

Perovskites from mantle xenoliths and kamafugites of the East African Rift Zone

Muravyeva N.S., Senin V.G.



Perovskite occurs in kamafugites as groundmass, phenocryst and component of the mantle xenoliths. In our work the composition of the perovskite from potassic and ultrapotassic volcanic rocks and containing in them xenoliths from East African Rift zone have been investigated. The content of major and trace (Ce, La, Nd, Nb, Cr, Na) elements was determined by electron microprobe analysis. Perovskite from kamafugites are homogeneous and zonal, but only homogeneous in xenoliths. The chemical zonation is the most clearly shown for Ce (Nd, La,Na, Fe and Nb). Both simple and complex - oscillatory zonation is in perovskites from studied samples. The type of zonation indicates to different dynamic of crystallization of this mineral  from melts various in composition (equilibrium and disequilibrium).

The oxygen fugacity estimated by oxygen barometer for kimberlitic (Bellis, Canil, 2007) indicates that the xenoliths have been formed in a more oxidized environment than containing them melts. The highest fO2 values corresponded to pyroxenite xenolith from Nyungu crater (the Bunyaruguru volcanic field).

The results obtained show that content of rare and rare-earth elements in perovskite from kamafugite are significantly higher than the similar contents in perovskites from xenoliths. Since perovskite is the main mineral-host of rare and rare-earth elements, it can be concluded that mantle source of kamafugite melts has been more enriched by rare and REE than the source of the xenoliths. It confirms the isotope data, obtained earlier on these samples.


Bellis A., Canil D., 2007 Ferric Iron in CaTiO3 Perovskite as an oxygen barometer for kimberlitic, Journal of Petrology, vol. 48, N2, p. 219-230