A new understanding of the provinces of the Amazon craton based on integration of field mapping and U-Pb and Sm-Nd geochronology

New conventional and sensitive high-resolution ion microprobe zircon U-Pb d ating has led to a new understanding of the subdivision and evolution of th e Amazon Craton during Precambrian time, with major improvements and change s made to the previous Rb-Sr based model. The interpretation of U-Pb and Sm -Nd isotopic data identifies eight main Precambrian tectonic provinces in t he Craton, with ages ranging from 3.1 to 0.99 Ga. Some of the provinces wer e generated by accretional, are-related processes (Carajas, Transamazonic, Tapajos-Parima and Rondonia-Juruena) and others by recycling of continental crust (Central Amazon, Rio Negro and Sunsas). The exposed Archean crust is restricted to the east (Carajas and south Amapa in Brazil) and north (Imat aca in Venezuela) of the craton, indicating that the Amazon Craton is large ly a Proterozoic crust. The Carajas-Imataca (3.10-2.53 Ga) and Transamazoni an (2.25-2.00 Ga) Provinces are composed predominantly of granite-greenston e terranes. The Tapajos-Parima (2.10-1.87 Ga) and Rondonia- Juruena (1.75-1 .47 Ga) Provinces represent new crust added as orogenic belts, while the Ri o Negro (1.86-1.52 Ga) and Sunsas (1.33-0.99 Ga) Provinces originated mainl y by magmatic-tectonic recycling of the above two orogenic belts. The only zone with a prominent northeast trend is the poorly known K'Mudku Shear Bel t, characterized by a similar to 1.20 Ga shear zone which deforms the rocks of at least three different provinces (Rio Negro, Tapajas-Parima and Trans amazonic). The Central Amazon Province comprises mostly Orosirian volcano-p lutonic rocks (Uatuma Magmatism) and is a terrane in which the exposed crus tal structure and deformation are pluton-related. The Sm-Nd T-DM model ages and epsilon(Nd) suggest that the Central Amazon Province was generated by the partial melting of Archean continental crust (Carajas Province?), perha ps related to underplating that began at the end of the Tapajos-Parima Orog eny (1.88-1.86 Ga).