Recent carbonatitic magmatism in Angola: the dykes of the Chiva lagoon maar



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Title: Recent carbonatitic magmatism in Angola: the dykes of the Chiva lagoon maar
Authors: Consorci del Museu de Ciències Naturals de Barcelona
Campeny, Marc
Melgarejo, Joan Carles
Mangas, José
Manuel, José
Gonçalves, Antonio Olimpio
Issue Date: 3-Mar-2017
Keywords: Magmatisme
Spatial coverage: Angola
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Citation: Boletín de la Sociedad Geológica Mexicana, (2017), volumen 69, número 1, p. 209-222.
Publisher: Sociedad Geológica Mexicana; Universidad Nacional Autónoma de México
Extent: 14 p.
Abstract: 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.
Terms of use: CC-BY-NC-ND
Appears in Collections:Mineralogia / Articles

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