Granites and migmatites of the Damara belt,South West Africa. Petrography and melting experiments |
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| Authors: | Dr Christoph Hoffmann |
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| Institution: | 1. Mineralogisches Institut, Hebelstra?e 40, D 7800, Freiburg
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| Abstract: | In the central area of the early paleozoic Damara belt migmatites and some types of granites (sensu lato) crop out. Conventional petrographic data were collected and melting experiments were carried out with 63 samples of such rocks. Based on these data, migmatite genesis can be classified as follows: - Formation by partial melting and separation of more liquid and more crystalline fractions, the melting behaviour of these fractions has to be principally similar then.
- Formation by injection of “geologically liquid” crystal-melt mixes into rocks of (incidentally) similar or (more frequently) dissimilar melting behaviour.
- Formation by partial melting of metasediments of originally different composition. The method is applied and demonstrated for outcrops with complicated interrelations and it is shown that temperature estimates are possible thereby (670° to 710° at 4–5 kb H2O pressure in the central Damara belt).
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