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Southwestern Africa on the burner: Pleistocene carbonatite volcanism linked to deep mantle upwelling in Angola

Citation

Giuliani, A and Campeny, M and Kamenetsky, VS and Afonso, JC and Maas, R and Melgarejo, JC and Kohn, BP and Matchan, EL and Mangas, J and Goncalves, AO and Manuel, J, Southwestern Africa on the burner: Pleistocene carbonatite volcanism linked to deep mantle upwelling in Angola, Geology, 45, (11) pp. 971-974. ISSN 0091-7613 (2017) [Refereed Article]


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DOI: doi:10.1130/G39344.1

Abstract

The origin of intraplate carbonatitic to alkaline volcanism in Africa is controversial. A tectonic control, i.e., decompression melting associated with far-field stress, is suggested by correlation with lithospheric sutures, repeated magmatic cycles in the same areas over several million years, synchronicity across the plate, and lack of clear age progression patterns. Conversely, a dominant role for mantle convection is supported by the coincidence of Cenozoic volcanism with regions of lithospheric uplift, positive free-air gravity anomalies, and slow seismic velocities. To improve constraints on the genesis of African volcanism, here we report the first radiometric and isotopic results for the Catanda complex, which hosts the only extrusive carbonatites in Angola. Apatite (U-Th-Sm)/He and phlogopite 40Ar/39Ar ages of Catanda aillikite lavas indicate eruption at ca. 500–800 ka, more than 100 m.y. after emplacement of abundant kimberlites and carbonatites in this region. The lavas share similar high-μ (HIMU)–like Sr-Nd-Pb-Hf isotope compositions with other young mantle-derived volcanics from Africa (e.g., Northern Kenya Rift; Cameroon Line). The position of the Catanda complex in the Lucapa corridor, a long-lived extensional structure, suggests a possible tectonic control for the volcanism. The complex is also located on the Bié Dome, a broad region of fast Pleistocene uplift attributed to mantle upwelling. Seismic tomography models indicate convection of deep hot material beneath regions of active volcanism in Africa, including a large area encompassing Angola and northern Namibia. This is strong evidence that intraplate late Cenozoic volcanism, including the Catanda complex, resulted from the interplay between mantle convection and preexisting lithospheric heterogeneities.

Item Details

Item Type:Refereed Article
Keywords:Africa, carbonatite, magmatism, mantle, rifting, dating, isotopes
Research Division:Earth Sciences
Research Group:Geology
Research Field:Igneous and Metamorphic Petrology
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
Author:Kamenetsky, VS (Professor Vadim Kamenetsky)
ID Code:122191
Year Published:2017
Funding Support:Australian Research Council (DP130100257)
Deposited By:CODES ARC
Deposited On:2017-11-04
Last Modified:2017-11-06
Downloads:0

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