U-Pb data on detrital zircons from Middle Cambrian siliciclastic levels of the Argentinean Precordillera: implications for the Cuyania terrane evolution

NAIPAUER MAXIMILIANO; CINGOLANI CARLOS ALBERTO; VUJOVICH GRACIELA IRENE; MCCLELLAND WILLIAMS

Bariloche, Argentina.

Simposio; VI South American Symposium on Isotope Geology; 2008

ABSTRACT The Argentine Precordillera has been recognized as an early Paleozoic suspect terrane of probable Laurentian origin, based on a combination of geological evidence. To constrain the paleogeographic models, geochronological research was carried out during the last years, based on Cambrian-Ordovician detrital zircon of the Precordillera terrane. The objective of the present paper is to extend our understanding of the provenance of the Precordilleran Cambrian units, using U-Pb detrital zircons geochronological data from siliciclastic levels intercalated in the carbonate platform. The U-Pb ages on detrital zircon grains analyzed from Middle Cambrian sedimentary rocks of the Precordillera terrane are characterized by an unimodal distribution, with a main frequency at ca. 1360 Ma. In conclusion, detrital zircons with ages from ca. 1360-1380 Ma are the most abundant in the studied Cambrian units from the Precordillera. This allows interpreting that the provenance is from igneous rocks (plutonic and volcanic), and with a lower proportion of metamorphic rocks. As it can be seen, these data clearly coincides in a derivation source and geochronology with a provenance from the Granite-Rhyolite Province of Laurentia. Finally, we point out that the detrital zircon provenance analysis the basement of the Cuyania Terrane have a an important component of ca. 1360-1380 Ma (Granite-Rhyolite Province) not exposed at the moment or was a direct connection with the Laurentian margin at least since 510 Ma (Middle Cambrian).