P-T CONDITIONS OF METAMORPHISM IN THE WAMI RIVER GRANULITE COMPLEX, CENTRAL COASTAL TANZANIA - IMPLICATIONS FOR PAN-AFRICAN GEOTECTONICS INTHE MOZAMBIQUE BELT OF EASTERN AFRICA

Solid-solution equilibria for garnet-clinopyroxene pairs in the early Pan-African Warni River granulite complex of central coastal Tanzania indicate metamorphic recrystallization at a temperature of about 700 d egrees C and a pressure of 8-9 kb, corresponding to metamorphism at a depth of 30-40 km. This suggests that granulite formation was preceded by an anomalous regional crustal thickening, similar to the crustal d oubling that accompanies Phanerozoic continent-continent collisions of the Himalaya type. The analogy prompts the interpretation of the Warn i River granulite complex, and possibly the rest of the granulite comp lexes in the Mozambique Belt, as slices of the underthrusted plate, wh ich were accreted to the present day African plate following a contine nt-continent collision during early Pan-African time. (C) 1997 Elsevie r Science Limited.