Agostinho Neto, Av. 4 de Fevereiro 7, 815 Luanda, Angola Earth and Ocean Sciences, School of Natural Sciences...Tchivira carbonatites occur in a plutonic complex, the Bonga carbonatites represent hypabyssal carbonatites and...(LILE) contents are very low. Pyrochlores from Bonga show oscillatory zonation; the F and Na contents...composition is similar to the Bonga pyrochlores. The rims are enriched in Zr, Ta, Th, Ce and U, but depleted in...exsolution in the volcanic carbonatites. K EY WORDS : Angola, carbonatite, zonation in pyrochlore, fluorine, |