Structure and evolution of the Austral basin fold-thrust belt, Southern Patagonian Andes

Abstract

This study focuses on the evolution of the Southern Patagonian Andes fold-thrust belt and the adjacent non-deformed foreland
of the Austral basin between 49°45' and 52°00'SL. This sector involves mainly Late Cretaceous sequences of the first regressive
cycle (Lago Viedma Cycle) of the Austral basin foreland stage, and Campanian to Paleogene sequences associated
with tectonic uplift of its western boundary. From a stratigraphic-sedimentary point of view, a first-order increase in the fillthickness
and depth to the basement exists from north to south including the presence of deeper depositional environments
in the same direction. Furthermore, there are strong along-strike variations in width and lateral position of the structural domains
following the same trend. Based upon previous interpretations, is concluded that the distribution of extensional depocenters
from the early extensional phase of the basin controlled these important sedimentary and structural N-S contrasts.
Furthermore, in our presented model, East-west oriented transition zones are interpreted as accommodation zones separating
synrift sub-basins.