U-Pb and Lu-Hf zircon data of the grenvilian arc-related Zâmbué, Fíngoè and Cazula supracrustal complexes, Southern Irumide Belt, NW Mozambique.
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2022
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Resumo
The supracrustal rocks from the Zˆ
ambu`e and Fíngo`e 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 Zˆ
ambu`e Supergroup comprises a succession of thick massive orthoquartzites and meta-arkoses, with minor calc-silicatic schists, marble, and a basal complex of ortho- and paragneisses. The Fíngo`e
Supergroup and Cazula Group are composed of metasandstones, calc-silicatic schists, and metapelites interlayered 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 Zambu ˆ `e
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 Fíngo`e 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 predominantly positive εHf(t) values (+2 and +10) and TDM
2 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 Zambu ˆ ´e and Fíngo`e 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).
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Detrital zircon, Metavolcano-sedimentary complexes, Juvenile magmatism, Irumide Orogeny, Rodinia assembly
Citação
PETRY, T. S. et al. U-Pb and Lu-Hf zircon data of the grenvilian arc-related Zâmbué, Fíngoè and Cazula supracrustal complexes, Southern Irumide Belt, NW Mozambique. Precambrian Research, v. 381, artigo 106860, out. 2022. Disponível em: <https://www.sciencedirect.com/science/article/pii/S0301926822003047#!>. Acesso em: 15 mar. 2023.