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
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.