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The Taita Hills–Galana River region is a key area to demonstrate the polycyclic nature of the Mozambique Belt in SE Kenya. On the basis of petrological and tectonic data, this area is composed of two different granulite-facies terranes, which are separated by the 20–30 km wide Galana Shear Zone. The Taita Hills and adjoining Sagala Hills exhibit a metamorphic overprint at 630–645 Ma, similar to areas in Tanzania. An emplacement age for the magmatic precursor rocks of 850–960 Ma was derived from zircon cores. Sm–Nd garnet–whole-rock analyses give an age of 585 Ma, interpreted as the cooling age after 630–645 Ma metamorphism. Nd crustal residence ages are between 1000 and 1500 Ma. The Galana Shear Zone east of the Taita Hills contains strongly deformed tonalitic migmatites with interlayered pegmatites that date a younger tectonometamorphic event at 560–580 Ma. East of the shear zone only a young metamorphic age of 550 Ma was found. The Nd model ages are c . 1500 Ma to c . 2900 Ma. In a continental configuration prior to Gondwana break-up our study area was located close to Madagascar, where several large shear zones are observed. One of these shear zones (Ranotsara Shear Zone) may be a continuation of the Galana Shear Zone.

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Amphibolites and orthogneisses from the Taita Hills-Galana River area (SE Kenya) indicate their broad geological-tectonic setting. There are groups of subduction-related rocks which show characteristic REE (rare earth element) patterns and enrichment or varying concentrations of HFS (high field strength) elements. The groups can be assigned to tectonostratigraphic domains marked by different structural styles (e.g., thrust-or strike slip dominated). Tholeiitic gneisses, often emerging as folded and isolated (ridge-shaped) leucocratic bodies, belong to a group of rocks located between the thrust-and strike-slip domain. Compared to calc-alkaline gneisses of the area they contain more mafic inclusions and have lower LIL (large ionic lithophile), HFS and light REE values. These gneisses have chemical characteristics of M-type granitoids of oceanic island arc signature. Intrusion ages of *955-845 Ma determined for these rocks suggest early Pan-African subduction. Mafic to ultramafic rocks from the Pare mountains of NE Tanzania show evidence of ophiolitic cumulates, subduction settings were also observed for the granulite areas in central and southern Tanzania. Together with the widespread arc settings documented in the Arabian-Nubian Shield, the presented data supports the continuation of an island-continental arc range across Kenya-Tanzania to Mozambique.

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