Piedmont glaciations, volcanism and landscape evolution in southernmost Patagonia, Argentina

BETTINA ERCOLANO; HUGO CORBELLA; PEDRO TIBERI; ANDREA CORONATO; GUILLERMINA MARDERWALD

Advances in Geomorphology and Quaternary Studies in Argentina

Springer

Lugar: Cahm; Año: 2021; p. 354 - 382

North of the Gallegos River valley, glacigenic deposits outcrop in twoaltimetric levels. The Meseta Latorre is the highest level (1,064 m a.s.l.), a relicof the ancient Andean piedmont. A degraded basal moraine and a frontal/lateralridge occupy the summit of the tableland. Their deposits are here recognized as theMeseta Latorre Drift, and considered as Late Miocene in age.The second piedmontlevel is located eastwards at an altitude of ~100mlower than the highest one.At itssurface, two nested systems of marginal moraines, with glaciofluvial deposits, arerecognized. The outer system is herein defined as the Los Vascos Drift, whereasthe inner one is the Bella Vista Drift, dated at ~1 Ma. This drift is equivalent tothe Great Patagonian Glaciation within the Gallegos River valley. Volcanic cones,lava flows, phreatomagmatic deposits and fluvial sediments were partially/totallyburied by both drift deposits. Volcanic activity is basaltic, transitional and alkalinein composition and it took place between 8.0 and 9.0 Ma, according to Ar40/Ar39dating. This paper presents new evidence about the extent of ancient glaciationsthat occupied the extra-Andean tablelands and its relationship with tectonism andvolcanism, as well as the landscape evolution.