Nd–Hf isotopic composition of the Paleoproterozoic Matupá and Teles Pires intrusive suites: Implications for crustal evolution of the southern Amazonian Craton (Brazil)

Abstract

This paper presents Nd–Hf isotopic data for granitic rocks of both the Matupá (∼1859–1881 Ma) and Teles Pires (∼1790–1793 Ma) intrusive suites located in the south-central region of the Amazonian Craton, central Brazil. The Matupá Intrusive Suite consists of two facies of I-type granites with calc-alkaline affinity emplaced in volcanic arc settings. Facies 1 is composed of syenogranite and monzogranite, and facies 2 is composed of granodiorite. The Teles Pires Intrusive Suite varies from syenogranite to monzogranite with calc-alkaline signature that is consistent with mature magmatic arc settings. The Matupá Intrusive Suite derives from a source with Hf model ages ranging between 2.4–1.91 Ga and εHf (t) between +5.71 and −5.50. Zircon grains in the Matupá Intrusive Suite that are correlatable with the Creporizão Intrusive Suite show Hf model ages of between 2.0 to 2.4, and εHf (t) of −3.76 to + 4.10, while the zircon grains correlatable with the Tropas Intrusive Suite show Hf model ages of 2.1 to 2.4 Ga and εHf(t) of −3.93 to + 2.50. Both facies of the Matupá Intrusive Suite provide εNd (t) values varying from −0.61 to −1.66. The wide range of εHf (t) values (from −5.50 to +5.71) in contrast to the uniformly negative εNd (t) values (from −1.66 to −0.61) of the Matupá Intrusive Suite suggest that Nd–Hf decoupling took place in the magma source during to magma mixing processes. Nd–Hf isotope analyses of the Teles Pires Intrusive Suite reveal a source with Hf model age of between 2.3 and 1.9 Ga. This is indicative of mantle contribution and crustal reworking with values of εHf (t) ranging from +7.17 to −3.3, while other values suggest a more crustal contribution with εNd (t) from −0.07 to −0.71. Crustal contribution in the genesis and magmatic evolution of the Teles Pires Intrusive Suite is also evidenced due to the presence zircon grains inherited from Matupá Intrusive Suite. Zircon inheritance record a distant parental source coeval with the Matupá Intrusive Suite. This paper proposes that the origin and evolution of the Matupá Intrusive Suite is linked to the Cuiú-Cuiú Magmatic Arc while the origin and evolution of the Teles Pires Intrusive Suite is linked to the Juruena Magmatic Arc. Another hypothesis is that both suites were generated and evolved from a single magmatic arc. The Juruena Magmatic Arc is divided into two geographic segments. An eastern segment with a magmatic evolution marked by the interaction of crustal components during the orogenic phase of the Cuiú-Cuiú Magmatic Arc (Tapajós Domain of the Tapajós-Parimá Tectonic Province), and a western segment whose magmatic evolution is marked by rebound of the Juruena Magmatic Arc.