U-PbSHRIMP and Sm-Nd geochronology of the Silvania Volcanics and Jurubatuba Granite: juvenile Paleoproterozoic crust in the basement of the Neoproterozoic Brasilia Belt, Goias, central Brazil

Citation
Dp. Fischel et al., U-PbSHRIMP and Sm-Nd geochronology of the Silvania Volcanics and Jurubatuba Granite: juvenile Paleoproterozoic crust in the basement of the Neoproterozoic Brasilia Belt, Goias, central Brazil, AN AC BRASI, 73(3), 2001, pp. 445-460
Citations number
33
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Multidisciplinary
Journal title
ANAIS DA ACADEMIA BRASILEIRA DE CIENCIAS
ISSN journal
0001-3765 → ACNP
Volume
73
Issue
3
Year of publication
2001
Pages
445 - 460
Database
ISI
SICI code
0001-3765(200109)73:3<445:UASGOT>2.0.ZU;2-T
Abstract
U-Pb SHRIMP and Sm-Nd isotopic ages were determined for felsic metavolcanic rocks from the Silvania Sequence and Jurubatuba Granite in the central par t of the Brasilia Belt. Zircon grains from a metavolcanic sample yielded 21 15 +/- 23 Ma and from the granite yielded 2089 +/- 14 Ma, interpreted as cr ystallization ages of these rocks. Six metavolcanic samples of the Silvania Sequence yielded a six-point whole -rock Sm-Nd isochron indicating a crystallization age of 2262 +/- 110 Ma an d positive epsilon (Nd)(T) = +3.0 interpreted as a juvenile magmatic event. Nd isotopic analyses on samples from the Jurubatuba Granite have Paleoprot erozoic TUN, model ages between 2.30 and 2.42 Ga and epsilon (Nd)(T) values vary between -0.22 and -0.58. The oldest TDM value refers to a sedimentary xenolith in the granite. These results suggest crystallization ages of Sil vania 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 Br asilia Belt that implies the presence of arc/suture hidden in reworked base ment of the Brasilia Belt.