Browsing by Author "Jackson, MPA"

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    High-grade metamorphism and migmatizaof the Namaqua metamorphic complex around Aus in the Southern Namib Desert, South West Africa
    (1976) Jackson, MPA; De Villiers, John; Kroner, A
    Rocks of the Namaqua Metamorphic Complex are exposed in an area of 10 000 km² in the northwestern part of the Namaqua Mobile Belt east of Liideritz. The Garub sequence represents the oldest rocks in the Aus area and comprises a diverse group of layered rocks of mainly semi-pelitic, pelitic, mafic, calcareous and quartzose composition. These rocks have been metamorphosed to form marbles, calcitic gneisses, metaquartzites, biotite schists, sillimanitecordierite garnet gneisses, amphibolites and granolites with minor amounts of iron formation and magnesian rocks. The principal metasediments are concentrated in west-trending zones. A central zone of calcareous rocks broadens westwards and contains the largest known bodies of carbonate rocks in the Namaqua Metamorphic Complex. The calcareous zone is bounded in the north by a narrow beit of quartzose rocks and in the south, by a broad zone of aluminous rocks. Gradational rock types between these zones are compatible with original sedimentary lithofacies changes. Layered biotite gneiss of psammitic composition has been interfolded with units of the Garub sequence. Both these rock units are present as inclusions within a tonalitic augen gneiss.