Anais da Academia Brasileira de Ciências | |
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 | |
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】
CC BY
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