The Sm-Nd isotopic method in the geochronology laboratory of the University of Brasília

Abstract

Nd isotopes represent one of the best tools to investigate the processes involved in the evolution of the continental crust and mantle. This is due mainly to the similar geochemical behaviour of Sm and Nd, both light rare earth elements, which inhibits their fractionation during most varied geological processes. In order to carry out crustal evolution studies in central Brazil, the Sm-Nd isotopic method was implanted at the Geochronology Laboratory of the University of Brasília. The Sm-Nd separation methodology is basically that described in Richard et al. (1976), with the addition of some improvements. In this study we describe in detail the methodology used in Brasília. Precision and accuracy were checked with the international standards such as JB-3, BCR-1, BHVO-1 and La Jolla, and the following results were found: JB-3 (Nd=15.74 ppm and Sm=4.28 ppm), BCR-1 ( 143 Nd/ 144 Nd=0.512647±8, Nd=28.73 ppm and Sm=6.66 ppm), BHVO-1 (Nd=24.83 ppm and Sm=6.2 ppm) and La Jolla ( 143 Nd/ 144 Nd=0.511835±14).

Rhyacian evolution of the eastern São Luís Craton: petrography, geochemistry and geochronology of the Rosário Suite

“…Sm-Nd isotopic analyses of four granitoids were performed at the Isotope Geology Laboratory (Pará-Iso Lab) of Geoscience Institute of Federal University of Pará following the analytical procedures of Gioia and Pimentel (2000) and Oliveira et al (2008). Approximately 100 mg of whole-rock powders were mixed with 100 mg and 149 Nd spike solution and dissolved in Savillex capsules using the HNO 3 , HF and HCl acids.…”

K'Mudku A-type magmatism in the southernmost Guyana Shield, central-north Amazon Craton (Brazil): the case of Pedra do Gavião syenogranite

“…U-Pb diagrams and age calculations were done using ISOPLOT version 3.0 (Ludwig 2003) and errors for isotopic ratios are presented at the 1σ level. ■ Sm-Nd isotopic analyses followed the method described by Gioia & Pimentel (2000). Whole rock powders (ca.…”

U-Pb and Sm-Nd data of the Rhyacian and Statherian Orthogneisses from Rio Piranhas-Seridó and Jaguaribeano Terranes, Borborema Province, Northeast of Brazil

“…The samples were crushed and milled at the Department of Geology of the Federal University of Rio Grande do Norte (UFRN). The analyses were performed at the Laboratory of Isotopic Geology, at the University of Brasília, following the procedures described by Bühn et al (2009) for U-Pb and Gioia (2000), and those mentioned by Pimentel (2000) for the Sm-Nd analyses. The ISOPLOT, version 3.0 software, was used to calculate the ages according to Ludwig (2003).…”