The southern Central Andes recorded retroarc shortening, basin evolution, and magmatic arc migration during Neogene changes in subduction. At 31-33°S, above the modern flat-slab segment, spatial and temporal linkages between thin-and thick-skinned foreland shortening, basement-involved exhumation of the main Cordillera, and lower-crustal hinterland thickening remain poorly resolved. We integrate new geochronological and thermochronological data for thrust sheets and Neogene foreland basin fill with structural, sedimentological, and passive seismic results to reconstruct the exhumation history and evaluate potential geometric linkages across structural domains. 40 Ar/ 39 Ar ages for volcanic horizons and zircon U-Pb ages for synorogenic clastic deposits in the Manantiales Basin constrain the minimum duration of synorogenic sedimentation to~22-14 Ma. Detrital zircon age distributions record sequential unroofing of hinterland thrust sheets until~15 Ma, followed by eastward (cratonward) advance of the deformation front, shutoff of western sediment sources, and a shift from fluvial to alluvial fan deposition at 14 Ma. Apatite (U-Th)/He cooling ages confirm rapid exhumation of basement-involved structural blocks and basin partitioning by~14-5 Ma, consistent with the timing of the Manantiales facies and provenance shifts and a coeval (~12-9 Ma) pulse of thin-skinned shortening and exhumation previously identified in the eastern foreland. Late Miocene-Pliocene (~8-2 Ma) cooling ages along the Chile-Argentina border point to hinterland uplift during the latest stage of Andean orogenesis. Finally, geophysical constraints on crustal architecture and low-temperature thermochronometry results are compatible with a hybrid thin-and thick-skinned décollement spanning retroarc domains.
Understanding the effects of flat slab subduction on mountain building, arc magmatism, and basin evolution is fundamental to convergent‐margin tectonics, with implications for potential feedbacks among geodynamic, magmatic, and surface processes. New stratigraphic and geochronological constraints on Cenozoic sedimentation and magmatism in the southern Central Andes of Argentina (31°S) reveal shifts in volcanism, foreland/hinterland basin development, sediment accumulation, and provenance as the retroarc region was structurally partitioned during slab flattening. Detrital zircon U‐Pb age distributions from the western (Calingasta basin), central (Talacasto and Albarracín basins), and eastern (Bermejo foreland basin) segments of the retroarc basin system preserve syndepositional volcanism and orogenic unroofing of multiple tectonic provinces. Initial shortening‐related exhumation of the Principal Cordillera at 24–17 Ma was recorded by the accumulation of distal eolian deposits bearing Oligocene–Eocene zircons from the Andean magmatic arc. The Calingasta basin chronicled volcanism and basement shortening in the Frontal Cordillera at ~17–11 Ma, as marked by an upward coarsening succession of fluvial to alluvial fan deposits with a sustained zircon U‐Pb age component that matches pervasive Permian‐Triassic bedrock in the hinterland. An ~450 km eastward inboard sweep of volcanism at 11 Ma coincided with the inception of flat slab subduction, and subsequent thin‐skinned shortening in the Precordillera fold‐thrust belt that exhumed wedge‐top deposits and induced cratonward (eastward) advance of flexural subsidence into the Bermejo foreland basin. This foreland basin was structurally partitioned as basement uplifts of the Sierras Pampeanas transformed a fluvial megafan sediment routing network into smaller isolated alluvial fan systems fed by adjacent basement blocks.
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