U-PB DETRITAL AGES ON TUFFACEOUS AND SANDSTONE LEVELS FROM A NEOGENE THICK FORELAND BASIN OF THE CENTRAL ANDES OF ARGENTINA.

COLLO, GILDA; DAVILA, FEDERICO; EZPELETA, MIGUEL; TEIXEIRA, WILSON

Congreso; II Congresso de Geología dos países de Lingua Portuguesa; 2014

Six tuffaceous and sandstone levels from an Andean (Mio-Pliocene) synorogenic succession were analyzed using the U-Pb LA-ICP-MS method on zircons, in order to constrain maximum depositional ages and to define the basin provenance and likely connections with the volcanic history of the South-Central Andes. The detrital ages of the different samples were rather similar, ranging from ~2007 to ~5 Ma (Paleoproterozoic to Cenozoic). The pool of ages suggests reworking and high detrital contamination of the volcaniclastic levels. The main detrital populations have age mode at 460 and 480Ma (Ordovician) and three main Andean volcanic episodes at ~5, 13 and 21Ma were identified. From these new data sets, a sedimentation rate of ~0.7mm/yr would characterize the basin fill between ~13 and 5 Ma.