U-Pb and Lu-Hf zircon data of the grenvilian arc-related Zambue, Fingoe and Cazula supracrustal complexes, Southern Irumide Belt, NW Mozambique

The supracrustal rocks from the Zambue and Fingoe Supergroups and the Cazula Group in the Mesoproterozoic Southern Irumide Belt (SIB) of NW Mozambique provides a sedimentation record associated with the Rodinia supercontinent. The Zambue Supergroup comprises a succession of thick massive orthoquartzites and meta-ar-koses, with minor calc-silicatic schists, marble, and a basal complex of ortho-and paragneisses. The FIngoe` Supergroup and Cazula Group are composed of metasandstones, calc-silicatic schists, and metapelites interlay-ered with felsic, mafic, and ultramafic metavolcanic rocks. U-Pb and Lu-Hf isotopic determinations of detrital zircon from five key samples show similar ages for the main source rocks. Detrital zircon from the Zambue Supergroup range between 1208 and 1086 Ma in age, with a restricted contribution of Paleoproterozoic source rocks. The maximum depositional age was established at 1110 +/- 2 Ma. The Fingoe Supergroup shows zircon ages between 1233 and 1106 Ma, with a subordinate contribution of Paleoproterozoic and NeoArchean zircon grains. The calculated maximum depositional age of 1142 +/- 6 Ma is similar to the crystallization age of 1094 +/- 9 Ma obtained from a meta-andesite, and indicates the syn-orogenic nature of these volcanism. In the Cazula Group samples, the zircon ages range between 1164 and 1076 Ma, with minor Paleoproterozoic contributions. The maximum depositional ages were established at 1076 +/- 1 Ma and 1139 +/- 1 Ma. The Lu-Hf data show pre-dominantly positive epsilon Hf(t) values (+2 and +10) and TDM2 ages ranging between 1.75 and 1.50 Ga, indicating isotopic signatures of juvenile sources, with limited older continental crust contributions. The age results, the well-defined young age modes of the detrital zircon associated with the arc magmatism of the Southern Irumide Belt and the Hf isotopic composition demonstrate that the Zambue and Fingoe Supergroups and Cazula Group represent arc-related basins. Structural data indicate a complex and polyphasic evolution, with the development of the metamorphic foliations associated with Mesoproterozoic transpressional oblique tectonics, related to accretionary and collisional phases of the Irumide Orogeny (1200-1000 Ma).