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Cobertura geogràfica
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14 p.
Nota
Chiva is a circular lagoon with a diameter of 900 m, located in the vicinity of the Catanda graben (Angola).
This area is largely covered by Quaternary lacustrine sediments, however, a few dykes of carbonatiticcomposition have been found near the SE shore of the lagoon. The intrusion of these carbonatitic dykes has been linked to the occurrence of
recent volcanic events in the Chiva area and interpreted as feeding channels of an eruptive centre with maar
morphology. The Chiva carbonatitic dykes show a finely porphyritic texture formed by phenocrysts of subhedral
calcite (60 %), apatite (30 %) and magnetite (10 %) hosted in a fine calcite-rich ground mass that also
contains accessory minerals such as pyrochlore, perovskite and kimzeyite.
The mineralogical and compositional features of the Chiva dykes are similar o those described in some of the
carbonatitic lavas from the Catanda graben, suggesting that both volcanic events are genetically related. The
finding of this new eruptive centre enlarges the carbonatitic domain of Catanda and opens the door to
the discovery of new carbonatitic outcrops in this region of Western Angola.
Citació
Boletín de la Sociedad Geológica Mexicana, (2017), volumen 69, número 1, p. 209-222.