Granulite-facies metamorphism of the Palaeoproterozoic - early Palaeozoic gneiss domains of NE Mozambique, East African Orogen

Granulite-facies metamorphism recorded in NE Mozambique is attributed to three main tectonothermal events, covering more than 1400 Ma from Palaeoproterozoic - early Palaeozoic time. (1) Usagaran-Ubendian high-grade metamorphism of Palaeoproterozoic age is documented in the Ponta Messuli Complex by Grt-Sil-Crd-bearing metapelites, estimated to pressure (P) 0.75 +/- 0.08 GPa and temperature (T) 765 +/- 96 degrees C. The post-peak P-T path is characterized by decompression followed by near-isobaric cooling. (2) Irumidian medium- to high-pressure granulite-facies metamorphism is evident in the Unango and Marrupa complexes of late Mesoproterozoic - early Neoproterozoic age. High-pressure granulite-facies is documented by Grt-Cpx-Pl-Rt-bearing mafic granulites in the northwestern part of the Unango Complex, with peak conditions up to P = 1.5 GPa and T = 850 degrees C. Medium-pressure granulite-facies conditions recording P of c. 1.15 GPa and T of 875 degrees C are documented by Grt-Opx-Cpx-Pl assemblage in mafic granulites and charnockitic gneisses of the central part of the Unango Complex. (3) Tectonothermal activity during the Ediacaran-Cambrian Kuunga Orogeny is recorded in the Mesoproterozoic gneiss complexes as amphibolite facies to medium-pressure granulite-facies metamorphism. Granulite facies are documented by Grt-Opx-Cpx-Pl-bearing mafic granulites and charnockitic gneisses, reporting P = 0.99 +/- 13 GPa at T = 738 +/- 84 degrees C in the Unango Complex and P = 0.92 +/- 18 GPa at T = 841 +/- 135 degrees C in the Marrupa Complex. This metamorphism is attributed to crustal thickening related to overriding of the Cabo Delgado Nappe Complex, and shorthening along the Lurio Belt during the early Palaeozoic Kuunga Orogeny.