New insights on the Jurassic granites from Somoncura region, Patagonia, Argentina. (ISSN 0941-0414

GREGORI, D; BJERG, E A; SAINI-EIDUKAT, B

Profil

Universitaet Stuttgart

Lugar: Stutgart; Año: 2000 vol. 18 p. 1 - 4

0941-0414

The Alessandrini Complex crops out in the area of El Cuy, Somoncura Region, in the Argentine Patagonia. Recent field work allowed to recognize that it is constituted by three facies, namely granites (Alessandrini granite) which in turn are crosscut by dacite and rhyolite dykes, all of them in turn crosscut by mafic dikes. These rocks acquire a special significance since they have been dated as of Early Jurassic age (192 Ma). Major and trace element analyses as well as isotopic relationships indicate that the Alessandrini Complex has a volcanic arc signature and most probably evolved from a mantle source. Comparison with lower Paleozoic and Permo-Triassic plutonic complexes cropping out in proximal areas, despite age differences show that the formers have a wide compositional range whereas the Alessandrini Complex has a restricted composition, a reasonable fact considering its tectonic setting.