40Ar/39Ar Cooling Ages of the Paraguay Belt in the Nova Xavantina Region (MT): Tectonic Implications for Western Gondwana Collage

Authors

  • Mauro César Geraldes Universidade do Estado do Rio de Janeiro, Faculdade de Geologia, Departamento de Mineralogia e Petrologia Ígnea, Rua São Francisco Xavier, 524, 20550-013, Maracanã, Rio de Janeiro, RJ, Brasil
  • Anderson Costa dos Santos Universidade do Estado do Rio de Janeiro, Faculdade de Geologia, Departamento de Mineralogia e Petrologia Ígnea, Rua São Francisco Xavier, 524, 20550-013, Maracanã, Rio de Janeiro, RJ, Brasil
  • Werlem Holanda dos Santos Universidade do Estado do Rio de Janeiro, Faculdade de Geologia, Departamento de Mineralogia e Petrologia Ígnea, Rua São Francisco Xavier, 524, 20550-013, Maracanã, Rio de Janeiro, RJ, Brasil
  • Colombo Tassinari Universidade de São Paulo, Instituto de Geociências, Centro de Pesquisas Geocronológicas, Rua do Lago, 562, 005508-900, Cidade Universitária, São Paulo, SP, Brasil.

DOI:

https://doi.org/10.11137/2018_3_351_362

Keywords:

40Ar/39Ar, Metamorphism, Paraguay Belt, Western Gondwana

Abstract

40Ar/39Ar analysis were carried out on biotite crystals from the Paraguay Belt rocks in Nova Xavantina region (Mato Grosso State, Brazil) with the purpose to constrain the age from the regional metamorphic event. The samples are metavolcanic mafic rocks deformed during Brasiliano-Panafrican events. The 40Ar/30Ar plateau ages range from 541.6 ± 0.4 Ma to 531 ± 0.6 Ma and define the cooling period of regional metamorphic event related to the collision between the Amazonian craton and Paranapanema block, the final stages of the western Gondwana assembly. The Paraguay Belt association cropping out in this region comprise metamorphosed sedimentary (chemical and siliciclastic) and volcanic (basic and intermediary) rocks related to an ocean floor geological setting (Xavantina Ocean). This work presents two new ages for two biotite grains and compares with literature data suggesting that the 40Ar/39Ar data here reported and geological evidence indicates that the metabasic rocks present metamorphic ages in the range from 541 Ma to 531 Ma and their protolith about 700-648 Ma or older.

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Published

2019-10-16

Issue

Vol. 41 No. 3 (2018)

Section

Article

License

This journal is licensed under a Creative Commons — Attribution 4.0 International — CC BY 4.0, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.