Fe–Ti(–V) oxide deposits of the Kunene anorthosite complex (SW Angola): Mineralogy and thermo-oxybarometry

Cristina Villanova-de-Benavent, Lisard Torró, Montgarri Castillo-Oliver, Marc Campeny, Joan Carles Melgarejo, Xavier Llovet, Salvador Galí, Antonio Olimpio Gonçalves

Research output: Contribution to journalArticle

Abstract

The Kunene Intrusive Complex (KIC), in NW Namibia and SW Angola, is one of the largest Proterozoic anorthosite massif-type exposures in the world. A geochemical, mineralogical and petrological study of four Fe–Ti(–V) oxide bodies located in the understudied Angolan part of the KIC has been performed. The massive Fe–Ti(–V) oxide bodies, locally apatite-rich (nelsonites), are lenticular or dike-like. They consist mostly of titaniferous magnetite, ilmenite and minor aluminous spinel, apatite, olivine and graphite. Titaniferous magnetite displays a wide variety of subsolvus features, including aluminous spinel–magnetite–ulvöspinel exsolutions and ilmenite (Trellis) exsolutions. This work estimated the composition of the titaniferous magnetite prior to the exsolution, in order to calculate the temperature and oxygen fugacity of the different lithologies of each ore body. The thermo-oxybarometry results obtained range from 600 C to 820 C and f O2 from 10−24.7 to 10−14.7. These values do not correspond to magmatic crystallization in equilibrium, but to a later re-equilibration. In addition, the mineralogical and geochemical results indicate that the studied ore bodies contain economic reserves of Ti, V, and possibly of P and REE.

Original languageEnglish
Article number246
JournalMinerals
Volume7
Issue number12
DOIs
Publication statusPublished - 14 Dec 2017

Keywords

  • Exsolution
  • Fe-Ti oxide thermometry
  • Ilmenite
  • Massif-type anorthosite
  • Nelsonite
  • Titaniferous magnetite

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    Villanova-de-Benavent, C., Torró, L., Castillo-Oliver, M., Campeny, M., Melgarejo, J. C., Llovet, X., Galí, S., & Gonçalves, A. O. (2017). Fe–Ti(–V) oxide deposits of the Kunene anorthosite complex (SW Angola): Mineralogy and thermo-oxybarometry. Minerals, 7(12), [246]. https://doi.org/10.3390/min7120246