DETRITAL ZIRCON DATING FROM ORDOVICIAN CLASTIC UNITS OF THE SAN RAFAEL BLOCK, PRECORDILLERA TERRANE, WESTERN ARGENTINA.

ABRE, P., CINGOLANI, C., ZIMMERMANN, U., CAIRNCROSS, B. AND CHEMALE JR, F.

Bariloche

Simposio; VI South American Symposium on Isotope Geology, 6 p. CD Rom; 2008

VI SSAGI

Abstract The Ponón Trehué Formation is the only sedimentary sequence known to record a primary contact with the basement of the Precordillera terrane, in its southwards extension named the San Rafael block. The Pavón Formation also outcrops within the mentioned block and was deposited by turbidite currents. Detrital zircon dating obtained from both Ordovician units constrains the provenance to have been mainly derived from Mesoproterozoic rocks, although the wider range of ages found for the younger Pavón Formation support the contribution from an eastern source. The underlain Mesoproterozoic basement Cerro La Ventana Formation was the main source for both clastic sequences, but the Western Pampeanas Ranges might have also provided detritus to the Pavón Formation. (Ver pdf completo)