Abstract
U-Pb SHRIMP and Sm-Nd isotopic ages were determined for felsic metavolcanic rocks from the Silv�nia Sequence and Jurubatuba Granite in the central part of the Bras�lia 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 Silv�nia Sequence yielded a six-point whole-rock Sm-Nd isochron indicating a crystallization age of 2262 � 110 Ma and positive eNd(T) = +3.0 interpreted as a juvenile magmatic event. Nd isotopic analyses on samples from the Jurubatuba Granite have Paleoproterozoic TDM model ages between 2.30 and 2.42 Ga and eNd(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 Silv�nia 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 Bras�lia Belt that implies the presence of arc/suture hidden in reworked basement of the Bras�lia Belt.
Original language | English |
---|---|
Pages (from-to) | 390-399 |
Journal | Anais da Academia Brasileira de Ciencias |
Volume | 73 |
Issue number | 3 |
Publication status | Published - 2001 |