Neoproterozoic granulite facies metamorphism and coeval granitic magmatism in the Brasilia Belt, Central Brazil: Regional implications of new SHRIMP U-Pb and Sm-Nd data

New SHRIMP U-Pb zircon ages combined with Sm-Nd isotopic characteristics of granulites and associated granitic rocks of the Anápolis-Itauç u Complex in the central-southern part of the Brasília Belt are presented and discussed in this study. Igneous crystallization ages obtained in zircon grains of orthogranulite and granites vary between 760 and 650 Ma. Growth of new zircon at ca. 650-640 Ma dates the high-grade metamorphism. Zircon cores from paragranulites and granites give U-Pb ages between 2.0 and 0. 8 Ga. T_DM model ages of the granulitic rocks fall into two age intervals: 2.3-1.9 and 1.7-1.4 Ga. ε_Nd(T) values are negative, varying between -9.29 and -1.42. SHRIMP U-Pb ages of zircon cores indicate that the granulite sedimentary protoliths were deposited after 800 Ma ago, contradicting previous models which assigned Paleoproterozoic or Archean ages for these rocks. Their Nd isotopic signature indicate that Paleoproterozoic sources (within the São Francisco Craton?), as well as younger sources, such as the Goiás Magmatic Arc, contributed to the sediment infilling of the former basin. The intrusive granites display Nd model age pattern similar to that of the granulitic rocks, with most T_DM model ages ranging between 1.45 and 1.2 Ga. ε_Nd(T) values are between -2.61 and -7.96, indicative of assimilation of older material by the original magma. SHRIMP U-Pb data for the granite intrusions indicate that granitoids metamorphosed under amphibolite facies show strong inheritance (between 2.1 and 0.8 Ga) and magmatic(?)/metamorphic age at ca. 660-650 Ma. The syn-granulite facies granitoid ANA 1 gave magmatic and metamorphic ages of ca. 650 Ma, without any discernible inheritance. The growth of new zircon occurred at the same time of the high-grade metamorphism, probably related with the collision event between the Goiás Magmatic Arc to the west-southwest and the São Francisco Craton, to the east. The data suggest that the Anápolis-Itauçu Complex, instead of representing the ancient sialic basement of the supracrustal rock units of the Brasília Belt, constitutes a Neoproterozoic high-grade metamorphic complex related with the evolution of the Brasiliano orogen.