Seismic interpretation and cenozoic tectonic evolution of the Pozuelos Basin, Andean plateau, Argentina

Abstract

The Andean basin formation across the Altiplano-Puna plateau has been mostly associated with: (i) interconnected depozones within a simple eastward-migrating foreland, (ii) isolated depocenters in a broken foreland or (iii) intermontane basins within a rising plateau setting. Particularly, the regions located further east from the western orogenic belts are key to disentangle these proposals. The Pozuelos Basin is today an internally-drained depositional area located at ~22°22′S in the easternmost Andean plateau (an area known as the Puna). While this basin might be key to understanding the formation of basins at these latitudes, between belts Puna and Cordillera Oriental, during the Andean orogeny, only a few studies have been done since most of their records are in subsurface. In order to address the Cenozoic formation and evolution of the Pozuelos Basin, and support some of the Andean basin formation hypotheses, we conducted seismic data interpretation, complemented with field surveys. Data allowed the correlation of seismic reflectors, five identified tectono-sequences (two basements –non-stratified and stratified– packages and three stratified Cenozoic packages) and subsurface structures with the local outcropping geology. In contrast to other areas from the Puna and Altiplano, the Pozuelos basin seems to have been affected by basement thrusting and deformation along its eastern boundary, previous to the late Miocene plateau formation. Despite that in the basin configuration was clearly an isolated and intermontane setting since the late Miocene, seismic and stratigraphic data suggest that during the Late Oligocene - Middle Miocene the Pozuelos basin would have behaved as well as a disconnected depositional zone. Some features like sequence encroachments and stratigraphic arrangements in outcrops drove us to interpret an intermontane broken foreland.