Meso‐Cenozoic Geodynamic Evolution of the Patagonian Foreland: Insights From Low‐Temperature Thermochronology in the Deseado Massif

Understanding how geodynamic processes (i.e., slab dynamics, rifting, plume activity) govern far-field stress propagation in the foreland and the magnitude of deformation in Andean-type orogens remains unclear. The Deseado Massif in the Patagonian foreland offers an opportunity to explore this, considering the influence of Gondwana break-up and the Chon Aike volcanic event, among others, on its development. This study utilizes apatite (U-Th)/He and fission track thermochronology on Paleozoic to Mesozoic basement and volcanic rocks, along with inverse modeling, as well as hematite and Mn-oxide (U-Th)/He geochronology on Jurassic ore-deposits, to reconstruct the Meso-Cenozoic tectono-thermal history of this region. The thermal histories reveal a Permo-Triassic cooling event linked to regional exhumation during Gondwana breakup. The subsequent Middle Jurassic heating event is primarily associated with the burial of bedrocks beneath >1 km of Chon Aike volcanic deposits. Exhumation events between Late Jurassic and Early Cretaceous are attributed to the reactivation of inherited structures according to the main stress direction controlled by changes in plate convergence with the opening of Weddell Sea, Rocas Verdes Basin and South Atlantic Ocean. Following a prolonged phase of thermal stability or moderate heating during the Late Cretaceous-Paleogene, the Deseado Massif experienced moderate regional uplift during the Miocene, as detected with oxides dates consistent with a weathering event during a river incision period. These findings highlight the interplay of geological factors shaping the tectono-thermal evolution of the Deseado Massif and demonstrate how concurrent extensional processes can trigger major exhumation in forelands by reactivating preferentially oriented inherited structures.