The amphibolites of the costeiro complex in the São Sebastião region, SP

Authors

  • Coriolano de Marins e Dias Neto Universidade de São Paulo; Instituto de Geociências; Departamento de Mineralogia e Geotectônica
  • Ciro Teixeira Correia Universidade de São Paulo; Instituto de Geociências; Departamento de Mineralogia e Geotectônica
  • Colombo Celso Gaeta Tassinari Universidade de São Paulo; Instituto de Geociências; Departamento de Mineralogia e Geotectônica
  • Jose Manuel Urbano Munhá Universidade de Lisboa; Faculdade de Ciências; Departamento de Geologia

DOI:

https://doi.org/10.5327/Z1519-874x2009000300005

Keywords:

Costeiro Complex, Ribeira Fold Belt, Brasiliano Cicle

Abstract

Geochronological, petrographic and lithochemical data have been used to characterize the crustal evolution and the thermochronology of the Costeiro Complex, São Paulo State, Brazil. This part of the Ribeira Fold Belt is composed of paraderived rocks to the East, and orthoderived rocks to the West, which are organized along a ductile shear zone forming a positive flower structure whose axis runs ENE-WSW. The main amphibolite occurrences are found within predominant garnet-paragneisses along this axis. The age of crystallization of the intrusive basic magmas which originated the amphibolites was 580 Ma (U-Pb SHRIMP). They formed tabular intrusions or secondary magma chambers, that locally still preserve continental tholeiitic geochemical characteristics. The close proximity of the basic magmatism and the metamorphic peak is evident from the 570 Ma, U-Pb age determination of the overgrowths on detritic zircon crystals in the paragneisses. This suggests a tectonic environment where the basic magmas intruded a back-arc sedimentary basin established over continental crust. The source areas were probably rocks differentiated from the mantle between the Paleoproterozoic and Neoproterozoic.

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Published

2009-10-01

Issue

Vol. 9 No. 3 (2009)

Section

Articles

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How to Cite

Dias Neto, C. de M. e, Correia, C. T., Tassinari, C. C. G., & Munhá, J. M. U. (2009). The amphibolites of the costeiro complex in the São Sebastião region, SP . Geologia USP. Série Científica, 9(3), 71-87. https://doi.org/10.5327/Z1519-874x2009000300005