The Famatinian orogenic system: Re-evaluating a long-lived Paleozoic subduction–collision system through tectono-stratigraphic evolution and source-to-sink dynamics

Abstract

We present a multi-proxy reconstruction of the tectono-stratigraphic evolution of the Famatinian orogenic system, which records the transition from a subduction-related orogen developed along the southwestern Gondwana margin to a collisional system triggered by the accretion of the Cuyania terrane. By integrating stratigraphic architecture, tectono-magmatic constraints, subsidence patterns, petrography, detrital-zircon U-Pb geochronology, and quantitative provenance modelling, we reassess the evolution of this long-lived subduction–collision system from arc construction to post-orogenic decay. Our synthesis identifies six tectono-stratigraphic stages: (1) pre-collisional arc stage (ca. 492–470 Ma); (2) transition from subduction- to collision-related (ca. 470–462 Ma); (3) main collision marked by crustal thickening, arc shutdown, and flexural foreland basin development (ca. 462–447 Ma); (4) the Silurian Rinconada Phase (ca. 446–419 Ma); (5) a late syn-convergent stage characterized by westward migration of depocenters (ca. 419–395 Ma); and (6) a post-orogenic stage linked to isostatic rebound and sedimentary bypass after ca. 395 Ma. This re-evaluation supports an oblique and diachronous collision of the Cuyania terrane with Gondwana, initiating in the northern sector and progressively propagating southward. Finally, Early Devonian deformation is interpreted as the terminal, low-convergence stage of the Famatinian collisional system, rather than the onset of the Chanic Orogeny. These results contribute to understanding the evolution of the Paleozoic composite Terra Australis Orogen along the southwestern margin of Gondwana and provide a well-constrained example of coupled tectonic and sedimentary evolution in long-lived convergent margins.