Abstract
The metamorphic belt of AI-Zurbi area is situated in a tectnically active region and was subjected to at least three regional deforrational phases. , The belt is of amphibolite facies and comprises migmatites and non-~igmatitie rocks. The migmatites are dominantly granitic in composition and comprise migmatite leucosomes and migmatite palaeosomes fractions. The chemistry and mineralogy of the migmatite palaeosomes are similar to those of the gneisses. The migmatite leucosomes show stromatic and ptygmatic structures. The average composition of the migmatite leucosomes accords reasonably well with that of the low-Ca granites. The migm~tite palaeosomes have higher total iron, Ti02, CaO, MgO, Sr, Ni, Zr, and Co arid lower Si02, K20, Rb, Nb, Cu, and Y contents relative to the high-Ca granitic rocks. The migmatite leucosomes are believed to have been formed by partial melting of metasediments with different proportions of alkalis and calcium, at relatively low temperatures and low water activity. The melts were crystallized together with the unmelted solids (restites).
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