Convergence and extension driven by lithospheric gravitational instability: evolution of the Alpine–Carpathian–Pannonian system

摘要: SUMMARY Lithospheric gravitational instability may play a significant role in the Neogene Alpine‐ Carpathian‐Pannonian system, where extensional Pannonian Basin formed over ∼10 Myr period simultaneously with contraction surrounding Alpine and Carpathian orogens. We investigate idea that collapse of low-density crust, previously thickened collision European plate Adria, has caused simultaneous development depth-variable lithospheric thinning beneath contractional deformation arc. Implicit this model is asthenospheric upwelling basin downwelling mountains. interplay between convergence extension type continental orogen using 2-D axisymmetric finite element models. show how key parameters, such as crust to lithosphere thickness viscosity ratios, affect evolution system: an initially thicker enhances mantle leads greater degree mantle, stronger mantle. Increasing relative slows growth reduces crustal deformation. Relatively low viscosity, however, implies too rapid initial topography re-equilibration after induced by flow. Non-Newtonian localizes narrower spatial region shorter time interval, following relatively slower phase growth. In Alpine‐Carpathian‐Pannonian requires prior on order 150 km, 2 × 10 20 Pa s, strength similar