Revisiting the Crustal Structure and Kinematics of the Central Andes at 33.5°S: Implications for the Mechanics of Andean Mountain Building

摘要: The Andean belt is the only present-day active case example of a subduction-type orogeny. However, an existing controversy opposes classical views growth as east-verging retro-wedge, against recently proposed bi-vergent model involving primary west-vergent crustal-scale thrust synthetic to subduction. We examine these diverging by quantitatively re-evaluating orogen structural geometry and kinematics at latitude 33.5??S. first provide 3D-geological map build updated section east-vergent Aconcagua fold-and-thrust (Aconcagua-FTB), which appears critical unit in this controversy. combine data with geological constraints on nearby structures derive complete larger scale Principal Cordillera within forearc region. restore our integrate published chronological evolutionary showing evolving shortening part Andes. implies uplift Frontal basement since ~20-25 Ma, supported westward thrusting over crustal ramp that transfers further west across Cordillera. Aconcagua-FTB evidenced secondary roof atop large-scale antiform culmination estimate ~27-42 km Cordillera, ~30% absorbed Aconcagua-FTB. Finally, we findings structure eastern back-arc mountain front, cross-section entire Andes 33.5?? S. total orogenic ~31-55km, mainly Our results quantitative key inferences revisit orogeny compare it collisional alpine-type belts.