The monapo structure and intrusive complex - an example of large-scale alkaline metasomatism in northern mozambique

摘要

The Monapo Complex, Nampula province, northern Mozambique measrues 40 x 53 km and is one of the largest alkaline complexes on Earth. The rocks within the structure are very varied and include quartzites, marbles, pyroxenites, gneisses, nepheline gneisses, granites, syenites, calcsilicates, pegmatites and a single carbonatite. All rocks appear to have been metamorphosed to the pyroxene amphibolite facies. There is a marked concentricity to the lithologies which suggests the multiple intrusion of possible cone sheets. Leucogneisses in the east of the Complex are more radioactive than those in the west and may have been subject to metasomatic alteration caused by the intrusion of alkali granites. The Evate carbonatite is host to economic apatite mineralisation.