GRENVILLIAN MASSIF-TYPE ANORTHOSITES IN THE SIERRAS PAMPEANAS.

CASQUET, C.; RAPELA, C.W.; PANKHURST, R.J.; GALINDO, C.; DAHLQUIST, J.; BALDO, E.; SAAVEDRA, J.; GONZÁLEZ-CASADO, J.M.; FANNING, C.M.

JOURNAL OF THE GEOLOGICAL SOCIETY

Geological Society of London.

Lugar: Londres; Año: 2005 vol. 162 p. 9 - 12

0016-7649

We report the discovery of massif-type anorthosites in the Andean basement of the Western Sierras Pampeanas of Argentina. U–Pb zircon dating (SHRIMP) of a cogenetic gabbronorite dyke yields ages of 1070 ± 41 Ma for igneous emplacement and 431 ± 40 Ma for metamorphism. These anorthosites are petrologically and geochemically comparable to those of the Grenville province of Laurentia. Palaeogeographical reconstructions of Rodinia at 1.0–1.1 Ga suggest that the Sierras Pampeanas anorthosites were part of a large anorthosite province in the late Mesoproterozoic.