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BIBTEX RIS

Chapter 7.2 The Evolution and Tectonic Setting of the Luis Alves Microplate of Southeastern Brazil: An Exotic Terrane during the Assembly of Western Gondwana

2009; Elsevier BV; Linguagem: Inglês

10.1016/s0166-2635(09)01620-x

2452-1892

Miguel Ângelo Stipp Basei, Allen P. Nutman, Oswaldo Siga Júnior, Cláudia Regina Passarelli, Cesar O. Drukas,

Paleontology and Stratigraphy of Fossils

The Luís Alves Microplate (LAM) is an allochthonous block accreted to the eastern border of the Rio de La Plata and Paranapanema cratons, located between the Neoproterozoic Ribeira Belt and Dom Feliciano belts. It comprises an Archaean-Palaeoproterozoic basement (orthogneisses), a Neoproterozoic volcano-sedimentary cover and anorogenic alkaline–peralkaline granitoids. The geological history of the basement rocks is complex, including two high-grade metamorphic events (2,350 and 2,180 Ma). K-Ar cooling ages on biotite and amphibole of ca. 1,800 Ma indicate that the LAM has been stable since the Palaeoproterozoic, Brasiliano deformation being restricted to shear zones at its margins. An ophiolite and deformed Neoproterozoic calc-alkaline granitoids rocks at its north–northwestern margin record oceanic crust consumption followed by continental collision. In contrast, the southern margin of the LAM is covered by the Neoproterozoic Itajaí Group, a foreland basin that was deformed and overthrust by the Brusque Group in the Cambrian (ca. 535 Ma).