Large scale deformation in a locked collisional boundary: Interplay between subsidence and uplift, intraplate stress and inherited lithospheric structure in the late stage of the SE Carpathians evolution.

Abstract

The interplay between slab dynamics and intraplate stresses in postcollisional times creates large near-surface deformation, particularly in highly bent orogens with significant lateral variations in mechanical properties. This deformation is expressed through abnormal foredeep geometries and contrasting patterns of vertical movements. Intraplate folding is often the controlling mechanism, particularly when the orogenic belt is locked. The study of these tectonic processes in the SE Carpathians indicates a generalized subsidence period during latest Miocene-Pliocene times driven by the slab-pull and an intraplate folding due to an overall Quaternary inversion. The latter accommodates -5 km ESE-ward movement of this area with respect to the neighboring units, which creates complicated three-dimensional deformation patterns potentially driven at a larger scale by the interaction between the Adriatic indentor and the entire Carpathians system. The lithospheric anisotropy inherited from the subduction times concentrates strain and induces large-scale deformation far away from the active plate margins. This anisotropy is dynamic because of deep mantle processes related to the subducted slab during postcollisional times, such as thermal reequilibration or increase in slab dip. Copyright 2007 by the American Geophysical Union