A U-Pb SHRIMP crystallization age on zoned igneous zircon of 1105.5 +/- 4.1 Ma suggests that the ETG could be part of the magmatic complex forming the Grenvillian basement of the Western Sierras Pampeanas. (Sr-87/Sr-86)(1105) values of 0.70543 and epsilon Nd of +4.2 indicate a rather immature source for its origin, with similar initial isotopic ratios to those found in orthogneisses from elsewhere in the Western Sierras Pampeanas. On the other hand, Sm-Nd model ages (T-DM) for the ETG range from 1.20 to 1.39 Ga. Geochemical and isotopic signatures of the ETG could be explained by low-pressure partial melting from a basaltic source under high geothermal gradient conditions. This thermal anomaly could be associated with the 1.1 Ga global period of enhanced mantle plume activity, developing widespread global magmatism. (C) 2010 Elsevier B.V. All rights reserved.