Pre-Andean Tectonics and Basin Analysis of the Eastern Precordillera, Argentina

The Precordillera in the Andes of Argentina displays a complex Paleozoic stratigraphic record related to plate convergence along the western Gondwana margin. This study seeks to determine the competing influences of convergent margin tectonics (including subduction, terrane collision, and pre-Andean uplift) and regional glaciation (including regional erosion, sediment routing, and deposition) on basin evolution.

A well-exposed Paleozoic succession in the Sierra Chica de Zonda (near the city of San Juan), provides a unique perspective on the stratigraphic and structural relationships created during Gondwana’s evolution. Here, Carboniferous deposits (Jejenes Formation), comprised of conglomerate, sandstone, and mudstone of glacial and marine origin, fill paleo-canyons incised into Ordovician carbonates (San Juan Formation) and Silurian deep-marine clastic rocks (Rinconada Formation), characterized by sandstones, mudstones, and large olistoliths (exceeding 1000–10,000 m3).

This study delineates the key lithofacies, depositional systems, and basin configurations for the Paleozoic deposits. Integration of new U–Pb detrital zircon geochronology enables the reconstruction of sediment dispersal patterns throughout the Paleozoic in response to terrane accretion, tectonic deformation, and glacial erosion. These data help resolve debates over the regional tectonic setting of the Precordillera and the influence of the Late Paleozoic ice age glaciation during basin reorganization from a collisional foreland to a retro-arc foreland along the western Gondwana margin.