377–392 Tracing the chemical evolution of primary pyrochlore from plutonic to volcanic carbonatites: the role...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...carbonatites are volcanic in origin. In Tchivira pyrochlore, zoning is poorly developed; fluorine is dominant...(LILE) contents are very low. Pyrochlores from Bonga show oscillatory zonation; the F and Na contents