U-Pb SHRIMP and Sm-Nd geochronology of the Silvânia Volcanics and Jurubatuba Granite: juvenile Paleoproterozoic crust in the basement of the Neoproterozoic Brasília Belt, Goiás, central Brazil

Anais da Academia Brasileira de Ciências

Danielle P. Fischel²  MÁrcio M. Pimentel²  Reinhardt A. Fuck²  Richard Armstrong¹ 

[1] ,Universidade de Brasília Instituto de Geociências Brasília DF ,Brazil

关键词: U-Pb SHRIMP;    Sm-Nd isotopic data;    Brasília Belt;    basement rocks;    U-Pb SHRIMP;    dados isotópicos Sm-Nd;    Faixa Brasília;    embasamento;   

DOI  :  10.1590/S0001-37652001000300012

来源: SciELO

【 摘 要 】

U-Pb SHRIMP and Sm-Nd isotopic ages were determined for felsic metavolcanic rocks from the Silvânia Sequence and Jurubatuba Granite in the central part of the Brasília Belt. Zircon grains from a metavolcanic sample yielded 2115 ± 23 Ma and from the granite yielded 2089 ± 14 Ma, interpreted as crystallization ages of these rocks. Six metavolcanic samples of the Silvânia Sequence yielded a six-point whole-rock Sm-Nd isochron indicating a crystallization age of 2262 ± 110 Ma and positive epsilonNd(T) = +3.0 interpreted as a juvenile magmatic event. Nd isotopic analyses on samples from the Jurubatuba Granite have Paleoproterozoic T DM model ages between 2.30 and 2.42 Ga and epsilonNd(T) values vary between -0.22 and -0.58. The oldest T DM value refers to a sedimentary xenolith in the granite. These results suggest crystallization ages of Silvânia volcanics and Jurubatuba Granite are the first evidence of a ca. 2.14-2.08 juvenile magmatic event in the basement of the central part of the Brasília Belt that implies the presence of arc/suture hidden in reworked basement of the Brasília Belt.

【 授权许可】

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