Architecture and orogenic evolution of the northeastern Outer Carpathians from cross-section balancing and forward modeling

New balanced and restored cross-sections and a 2D kinematic model illustrate the present geometry of the northeastern Outer Carpathians and quantify their orogenic evolution between the late Eocene and the late Miocene (similar to 35.3 to similar to 11.0 Ma). The balanced cross-section is built on extensive surface and subsurface data and depicts an imbricate fan internally stacked along high-displacement out-of-sequence thrusts. Section restoration yielded 507 km of minimum orogenic shortening - at least similar to 230 km more than proposed in previous studies. Our shortening estimate relies on accurate thicknesses of lithostratigraphic units, in most cases thinner than applied before. The average convergence rate between similar to 35.3 and similar to 11.0 Ma is estimated at 20.8 km/My. The forward model, constrained by lower and upper ages of syn-orogenic deposits, traces the advance of the Outer Carpathian accretionary wedge and proves kinematic admissibility of the balanced and restored cross-sections. Progradation rates of the foreland basin depositional sequences, evolving from 9-11 km/My between similar to 41.5 and similar to 21.1 Ma to 22-39 km/My between similar to 21.1 and similar to 11.0 Ma, suggest a two-phase dynamics of the orogenic system. The acceleration of foreland migration at similar to 21.1 Ma likely reflects the onset of northward subduction retreat, linked to the rollback of the European lower plate that gave rise to coeval back-arc extension in the Pannonian Basin. (C) 2012 Elsevier B.V. All rights reserved.