Alkaline Rocks and Carbonatites of the World

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Bremen

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Occurrence number: 
116-00-045
Country: 
Namibia
Region: 
Kuboos-Bremen and Bremen Garub lines of intrusions
Location: 
Longitude: 17.93, Latitude: -27.87

The Bremen occurrence consists of a series of syenites, granites and some hybrid rocks that form an arcuate, sheeted complex. The rocks consist mainly of alkali feldspar, quartz, hornblende and mica, but some granite dykes contain riebeckite (Middlemost, 1967), although Allsopp et al. (1979) imply that riebeckite is also present in the granites and syenites. The latter authors also indicate the presence of a small circular outcrop of 'foid syenite' several hundred metres across towards the centre of the complex, but no details are give.

Age: 
Rb-Sr isochrons gave 553(13 and 514(9 Ma, all data giving an errorochron of 530(12 Ma; U-Pb on four zircon fractions gave 521(12 Ma (Allsopp et al., 1979).
References: 
ALLSOPP, H.L., KOSTLIN, E.O., WELKE, H.J., BURGER, A.J., KRONER, A. and BLIGNAULT, H.J. 1979. Rb-Sr and U-Pb geochronology of late Precambrian - early Palaeozoic igneous activity in the Richtersveld (South Africa) and southern South West Africa. Transactions of the Geological Society of South Africa, 82: 185-204.MIDDLEMOST, E. 1967. Petrology of the Bremen granite-syenite complex, South West Africa. Transactions of the Geological Society of South Africa, 70: 117-34.
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