Uplift history of northern Sierras Pampeanas broken foreland, Argentina: a preliminary river profile approach

NÓBILE, J.C., DÁVILA, F.M.,

Congreso; Congreso Geologico Argentino; 2011

Geomorphological, thermochronological and geophysical studies suggest the Argentine broken foreland (Fig. 1) rose differentially from N to S after ~5 Ma (Strecker et al., 2009), between the Pliocene and Pleistocene, likely associated to deep-seated lithospheric processes (Dávila et al., in rev.). The uplift is supposed to have occurred coevally with the Altiplano-Puna plateau rising. Some authors attribute the Altiplano uplift to an isostatic response that started with the densification and consequent removal of the lowermost lithosphere (delamination, Garzione et al. 2006). In contrasts, the N Sierras Pampeanas topographic anomaly was interpreted as a result of dynamic topography (Dávila et al., 2005) or lower crustal flow. But the Sierras Pampeanas broken foreland is a complex compressional basin-and-range region, where the basement-thrusting exhumation controls not only the short-wavelength topography but also the basin formation (Hilley and Strecker, 2005). Gravity data and basin analysis (Nóbile et al., 2010) shows also a remarkable step within the northern broken foreland topography. Altitudes varies from >2500 m, to the N, to