TY - JOUR
T1 - Fe–Ti(–V) oxide deposits of the kunene anorthosite complex (SW Angola)
T2 - Mineralogy and thermo-oxybarometry
AU - Villanova-de-Benavent, Cristina
AU - Torró, Lisard
AU - Castillo-Oliver, Montgarri
AU - Campeny, Marc
AU - Melgarejo, Joan Carles
AU - Llovet, Xavier
AU - Galí, Salvador
AU - Gonçalves, Antonio Olimpio
N1 - Publisher Copyright:
© 2017 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2017/12/14
Y1 - 2017/12/14
N2 - 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.
AB - 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.
KW - Exsolution
KW - Fe-Ti oxide thermometry
KW - Ilmenite
KW - Massif-type anorthosite
KW - Nelsonite
KW - Titaniferous magnetite
UR - http://www.scopus.com/inward/record.url?scp=85041403529&partnerID=8YFLogxK
U2 - 10.3390/min7120246
DO - 10.3390/min7120246
M3 - Article
AN - SCOPUS:85041403529
SN - 2075-163X
VL - 7
JO - Minerals
JF - Minerals
IS - 12
M1 - 246
ER -