Geochemistry of the Gabbro-Anorthosite complex of Southwest Angola

Mesoproterozoic rocks of Namibia and their plate tectonic setting

“…The Kunene Anorthosite Complex (KIC) is $350 kmlong and $80 km-wide, and represents one of the largest anorthosite bodies in the world (Silva, 1990). The KIC Fig.…”

“…1): (1) the Namaqua Metamorphic Complex (NMC) located southwest of the Hauchab-Excelsior-Lord Hill Shear Zone, and (2) the Sinclair Group basin to the northeast of this structure. Additional Mesoproterozoic complexes identified in Namibia include basement ''inliers'' within the Neoproterozoic Damara/Kaoko belts (Krö ner et al, 1991(Krö ner et al, , 2001Seth et al, 1998;Steven et al, 2000), and the ''Kunene Anorthosite Complex'', which straddles the border between Angola and Namibia and represents one of the largest AMCG-type (Anorthosite-Mangerite-Charnockite-Granite) intrusions in the world (Silva, 1990;Ashwal and Twist, 1994).…”

Mineralogy and cryptic layering of the Kunene anorthosite complex of SW Angola and Namibia

“…These petrographic data, combined with geochemical and isotopic data (Silva and Kruger, and Kruger and Silva, in preparation) indicate that the white anorthosite is an altered variant of other fresh rocks of the complex. This alteration is probably of Kibaran age (Silva, 1987(Silva, , 1988(Silva, , 1990. …”

“…The variation in composition across the intrusion can be illustrated as follows: the AI20 3 content is low (<3%), similar to that in pyroxenes from the Bushveld (Atkins, 1969;Markgraaff, 1976;Eales et al, 1986) and Skaergaard (Brown, 1957;Brown and Vincent, 1963). The relation Si-AI in the clinopyroxenes from the Kunene Complex was investigated by Silva (1988) who plotted the atomic proportions of Si and AI obtained from all data available in Kushiro's diagram (Kushiro, 1960), where magmas show higher Si-A1 ratios with fractionation. Pyroxenes fall in the tholeiitic field, but show no fractionation trend similar to that of pyroxenes from the Stillwater and Skaergaard Complexes (Kushiro, 1960).…”

Fe–Ti(–V) Oxide Deposits of the Kunene Anorthosite Complex (SW Angola): Mineralogy and Thermo-Oxybarometry

“…Therefore, the emplacement of the anorthosite and the felsic suites took place during the same igneous event [12]. These ages coincide with most Proterozoic anorthositic massif-type occurrences [21]. Furthermore, the red granites were dated by several authors [19,36,42,43] by Rb-Sr whole-rock isochrones.…”