Neogene reactivation of older structures evidenced by K?Ar fault gouge dating in northern Argentine broken foreland

NOBILE, J.C., COLLO, G., DÁVILA, F.M., WEMMER, K.

Simposio; IX South American Symposium on Isotope Geology; 2013

The Argentine northern broken foreland has been the subject of continuous research to determine the uplift and exhumation history of the region. High elevation mountains have been uplifted by N-S reverse faults (resulting from the Andean tectonic compression scenery that disrupted a W-E Miocene foreland basin. We performed K?Ar dating on fault gouge related clay minerals samples (illite) collected along a transect within the Sierra de Ambato. K-Ar ages (3 samples) range from ~ 360 to 220 Ma and become older with increasing grain-size (~ 360-311 Ma for 2-1 µm grain size fraction, ~326-286 Ma for 1-0.2 µm and ~291-219 Ma of