Reading Deep Mantle Processes from Sedimentary Basins

Subduction zones and collisional orogens exhibit a wide spectrum of surface responses that reflect evolving slab and mantle dynamics. Yet distinguishing the topographic and sedimentary signatures of variable trench motions, lithospheric delamination, slab tearing, and eventual slab break-off remains a major challenge. Here I explore how sedimentary basins and mountain belts record these deep geodynamic processes, focusing on the Alps–Carpathians system as a natural laboratory.

Using a combination of two-dimensional and three-dimensional thermo-mechanical models incorporating surface processes, sedimentation, hydration, melting, and magmatism, I investigate the evolution of forearc, foreland, and back-arc basins throughout the subduction cycle. The results demonstrate that slab advance and slab steepening generate long-wavelength dynamic subsidence and forearc basin development, whereas slab roll-back promotes upper-plate extension, arc rifting, lithospheric thinning, and back-arc basin formation.

These processes are illustrated through the Miocene evolution of the Alpine–Carpathian region, where eastward Alpine extrusion was coupled to Pannonian back-arc extension, Transylvanian forearc subsidence, and progressive uplift of the Carpathian arc during mantle lithosphere delamination and subsequent slab break-off. New results further examine the evolution of magmatism during the transition from roll-back to delamination and final slab detachment.

I discuss recent 3D models of slab tearing beneath collisional belts. Incorporating realistic passive-margin heterogeneity significantly slows tear propagation and generates long-lived tectonostratigraphic signals, including migrating depocenters and systematic basin asymmetries. These predictions provide a framework for interpreting observations from the Alps and other mountain belts, linking mantle-scale processes to preserved stratigraphic records.

Together, these results highlight how basin subsidence, uplift, magmatism, and sedimentary architecture can be used to discriminate between successive stages of subduction-zone evolution, offering a unified perspective on the surface expression of slab dynamics from active subduction to continental collision and post-collisional collapse.