Mineral chemistry and Nd isotopic composition of two anorthositic rocks from the Kunene complex (South Western Angola)

Slejko, F. F.; Demarchi, G.; Morais, Eduardo

doi:10.1016/s0899-5362(02)00007-6

Cited by 14 publications

(15 citation statements)

References 17 publications

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“…Based on satellite images Ashwal & Twist (1994) concluded that even this northern part of the KIC represents a composite massif, composed of at least eight separate anorthosite plutons. A similar interpretation has also been reached by Morais et al (1998) and Slejko et al (2002), who distinguished at least two individual anorthosite bodies in the Angolan part of the KIC, a northern and a southern zone, that display remarkable differences in their geochemical characteristics and mineralogy.…”

Section: Geological Frameworksupporting

confidence: 81%

“…11). Regarding their εNd (T) values of +3.0 to + 1.1, the anorthosites from the Namibian part of KIC strongly differ from two anorthosite samples of the Angolan KIC, for which distinctly lower εNd (T) values of -5.72 and -6.36 have been calculated by Slejko et al (2002). On the other hand, the 87 Sr/ 86 Sr (T) ratios of 0.7038 to 0.7045 constrained for the Angolan anorthosites by Morais et al (1998) are in the range of the values of the Namibian samples presented in this study (i.e.…”

Section: Sr and Nd Isotopic Datamentioning

confidence: 86%

“…(1) The majority of the KIC exposed in Angola displays a N-S elongation and is mainly composed of dark, weakly altered anorthositic rocks (mainly anorthosites and leucotroctolites; e.g. Carvalho and Alves, 1990, Silva, 1990, 1992, Ashwal and Twist, 1994, Morais et al, 1998, Slejko et al, 2002, Mayer et al, 2004. Based on satellite images Ashwal & Twist (1994) concluded that even this northern part of the KIC represents a composite massif, composed of at least eight separate anorthosite plutons.…”

Section: Geological Frameworkmentioning

confidence: 99%

“…In clear contrast to most anorthosite bodies world-wide, the Mesoproterozoic KIC experienced no prograde metamorphic overprint after its emplacement (e.g. Ashwal and Twist, 1994;Morais et al, 1998;Drüppel, 1999Drüppel, , 2003Drüppel et al, 2001;Slejko et al, 2002;Mayer et al, 2004) and hence allows direct study of the igneous processes that led to its formation.…”

Section: Introductionmentioning

confidence: 99%

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Petrology and isotope geochemistry of the Mesoproterozoic anorthosite and related rocks of the Kunene Intrusive Complex, NW Namibia

Drüppel

Littmann

Romer

et al. 2007

Precambrian Research

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1 2The intrusion of the large (c. 18.000 km 2 ) anorthosite body of the Kunene Intrusive 3Complex, Angola/Namibia, which is associated with minor marginal granite bodies and 4 syenite/syenodiorite dykes, marked the beginning of Mesoproterozoic igneous activity in NW 5 Namibia. Anorthosites display an igneous mineral assemblage of dominating plagioclase, 6 together with minor olivine, orthopyroxene or clinopyroxene, Fe-Ti oxides, whereas biotite 7 and pargasite are late-magmatic phases. Apatite is a common accessory phase. In regionally 8 associated felsic rocks K-feldspar, plagioclase, clinopyroxene and/or hastingsite crystallized 9 first, followed by interstitial quartz, hastingsite, Fe-Ti oxides, and titanite. would be expected from fractionation products of melts that previously formed extensive 1 plagioclase cumulates, and (4) δ 18 O values of magmatic feldspar from the felsic rock suite fall 2 in a restricted range (7.20-7.92 ‰) that is about 1.6 ‰ higher than the average igneous 3 plagioclase δ 18 O of the anorthosites and suggests a formation of the felsic melts by anatexis of 4 the lower crust. 5 6

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Section: Geological Frameworksupporting

confidence: 81%

Section: Sr and Nd Isotopic Datamentioning

confidence: 86%

Section: Geological Frameworkmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Petrology and isotope geochemistry of the Mesoproterozoic anorthosite and related rocks of the Kunene Intrusive Complex, NW Namibia

Drüppel

Littmann

Romer

et al. 2007

Precambrian Research

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“…1c). This model is in accordance with the low pressures (3-5 kbar) and shallow emplacement level postulated for anorthosites of the northern part of the Kunene Intrusive Complex exposed in Angola (Slejko et al, 2002).…”

Section: Contact Metamorphism Of the Orue Unit And Relation To Anorthsupporting

confidence: 89%

Upper‐amphibolite facies partial melting of paragneisses from the Epupa Complex, NW Namibia, and relations to Mesoproterozoic anorthosite magmatism

Brandt¹,

Klemd

2008

Journal Metamorphic Geology

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The evolution of the mineral assemblages and P-T conditions during partial melting of upperamphibolite facies paragneisses in the Orue Unit, Epupa Complex, NW Namibia, is modelled with calculated P-T-X phase diagrams in the Na 2 O-CaO-K 2 O-FeO-MgO-Al 2 O 3 -SiO 2 -H 2 O system. The close concordance of predictions from the phase diagrams to petrographic observations and thermobarometric results documents that quantitative phase diagrams are suitable to explain the phase relationships in migmatitic upper-amphibolite facies low-and medium-pressure metapelites, which occur in many high-grade metamorphic terranes worldwide. Different mineral assemblages in the migmatitic metapelites of the Orue Unit reflect regional discrepancies in the metamorphic grade: in a Northern Zone, early biotite-sillimanite-quartz assemblages were replaced via melt-producing reactions by cordierite-bearing assemblages. In a Southern Zone, they were replaced via melt-producing reactions by garnet-bearing assemblages while cordierite is restricted to rare metapelitic granofelses, which preserve Grt-Sil-Crd-Bt peak assemblages. Peak-metamorphic conditions of 700-750°C at 5.5-6.7 kbar in the Southern Zone and of 750°C at 4.5 kbar in the Northern Zone are estimated by integrating thermobarometric calculations with data from calculated mineral composition isopleths. Retrograde back-reactions between restite and crystallizing melt are recorded by the replacement of garnet by biotite-sillimanite and ⁄ or biotite-muscovite intergrowths.Upper-amphibolite facies metamorphism and partial melting (c. 1340-1320 Ma) in the rocks of the Southern Zone of the Orue Unit, which underwent probably near-isobaric heating-cooling paths, are attributed to contact metamorphism induced by the coeval (c. 1385-1319 Ma) emplacement of the Kunene Intrusive Complex, a huge massif-type anorthosite body. The lower-pressure metapelites of the Northern Zone are interpreted to record contact metamorphism at an upper crustal level.

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The provenance of northern Kalahari Basin sediments and growth history of the southern Congo Craton reconstructed by U–Pb ages of zircons from recent river sands

Gärtner

Linnemann

Hofmann

2013

Int J Earth Sci (Geol Rundsch)

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Mineral chemistry and Nd isotopic composition of two anorthositic rocks from the Kunene complex (South Western Angola)

Cited by 14 publications

References 17 publications

Petrology and isotope geochemistry of the Mesoproterozoic anorthosite and related rocks of the Kunene Intrusive Complex, NW Namibia

Petrology and isotope geochemistry of the Mesoproterozoic anorthosite and related rocks of the Kunene Intrusive Complex, NW Namibia

Upper‐amphibolite facies partial melting of paragneisses from the Epupa Complex, NW Namibia, and relations to Mesoproterozoic anorthosite magmatism

The provenance of northern Kalahari Basin sediments and growth history of the southern Congo Craton reconstructed by U–Pb ages of zircons from recent river sands

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