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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. doi:10.1029/2006TC001951.

[1] In front of the SE Carpathians Bend a very deep basin (Focsani Depression) developed in Miocene to Recent times. An important part of its subsidence occurred after the main stages of thrusting in the Carpathians. Apparently, the basin lies in the 'wrong' place and evolved in the 'wrong' time. In this study, we constrain its architecture and evolution by analyzing a large database consisting of more than 1000 km two-dimensional seismic lines and more than 60 wells. Around 13 km thick, Badenian-to-Quaternary ( < 16.5 Myr) sediments were deposited in the central part of the Focsani Depression. During the Badenian (16.5-13 Myr), the foreland (south of Trotus fault) underwent NE-SW directed extension and NW trending basins opened in the eastern Moesian platform. A NW-SE oriented area of subsidence stretched from the Transylvania basin through the Focsani Depression to the SE of the Moesian platform while thrusting was going on in the East European/ Scythian platform, East Carpathians, and Getic Depression. Starting with the Sarmatian (13-10 Myr), the Focsani Depression depocenter moved out of the Carpathian belt coeval with the exhumation of the south and the East Carpathians north of the Trotus fault. The basin became wider and was tilted toward the belt. Tilting was accompanied by dextral shearing mainly along the Intramoesian and Peceneaga-Camena faults. After Sarmatian times, subsidence occurred practically only SSE of Trotus fault. During Meotian-Pontian (10-5 Myr), subsidence slowed down. Stronger, Pliocene-Quaternary subsidence is coeval with normal faulting and shearing in Moesian platform. The western margin of the Focsani Depression was then tilted eastward, coeval with the exhumation of the bend zone and opening of the intramontane basins in the inner part of the belt. INDEX TERMS: 8105 Tectonophysics: Continental margins and sedimentary basins (1212); 0905 Exploration Geophysics: Continental structures (8109, 8110); 9335 Information Related to Geographic Region: Europe; 9604 Information Related to Geologic Time: Cenozoic; KEYWORDS: Carpathians foredeep, Focsani Depression, basin subsidence, extension, shearing, tilting. 2003.

Apatite fission track (AFT) and (U-Th)/He (AHe) thermochronology have been combined to constrain the exhumation history of the SE Carpathians. Cooling ages generally decrease from Cretaceous for the internal basement nappes (AFT ages), to Miocene-Quaternary (AFT and AHe, respectively) for the external sedimentary wedge. The AFT and AHe data show a Paleogene age cluster, which confirms a suspected but never demonstrated tectonic event. The new data furthermore suggest that the SE Carpathians have been affected by a middle Miocene exhumation phase related to continental collision, which occurred at rates of~0.8 mm/yr, similar to the one previously inferred for the East Carpathians. The SE Carpathian tectonic evolution, however, is overprinted by two younger exhumation events in the Pliocene--Pleistocene. The first exhumation phase (latest Miocene--early Pliocene) occurred at high exhumation rates (~1.7 mm/yr) and is interpreted as a tectonic event and/or associated with a sea level drop in the Paratethys basins during the Messinian low stand. The youngest recorded tectonic phase suggests rapid Pleistocene exhumation (~1.6 mm/yr) and is interpreted to represent crustal-scale shortening different in mechanics from collisional processes. The data suggest that the SE Carpathians did not develop as a typical double-vergent orogenic wedge; instead, exhumation was related to a foreland-vergent sequence of nappe stacking during collision and was subsequently followed by a large out-of-sequence shortening event truncating the already locked collisional boundary. Citation: Merten, S., L. Matenco, J. P. T. Foeken, F. M. Stuart, and P. A. M. Andriessen (2010), From nappe stacking to out-of sequence postcollisional deformations: Cretaceous to Quaternary exhumation history of the SE Carpathians assessed by low-temperature thermochronology, Tectonics, 29, TC3013, doi: 10.1029/2009TC002550.

The transition zone between the Alps and Dinarides is a key area to investigate kinematic interactions of neighboring orogens with different subduction polarities. A study combining field kinematic and sedimentary data, microstructural observations, thermochronological data (Rb-Sr and fission track), and regional structures in the area of Medvednica Mountains has revealed a complex polyphase tectonic evolution. We document two novel stages of extensional exhumation. The first stage of extension took place along a Late Cretaceous detachment following the late Early Cretaceous nappe stacking, burial, and greenschist facies metamorphism. Two other shortening events that occurred during the latest Cretaceous-Oligocene were followed by a second event of extensional exhumation, characterized by asymmetric top-NE extension during the Miocene. Top-NW thrusting took place subsequently during the Pliocene inversion of the Pannonian Basin. The Cretaceous nappe burial, Late Cretaceous extension, and the Oligocene(-Earliest Miocene) contraction are events driven by the Alps evolution. In contrast, the latest Cretaceous-Eocene deformation reflects phases of Dinaridic contraction. Furthermore, the Miocene extension and subsequent inversion display kinematics similar with observations elsewhere in the Dinarides and Eastern Alps. All these processes demonstrate that the Medvednica Mountains were affected by Alpine phases of deformations to a much higher degree than previously thought. Similarly with what has been observed in other areas of contractional polarity changes, such as the Mediterranean, Black Sea, or New Guinea systems, the respective tectonic events are triggered by rheological weak zones which are critical for localizing the deformation created by both orogens. [ABSTRACT FROM AUTHOR]

Presents a derivation of the tectonic evolution of the South Carpathians-Moesian platform area. Depth-interpreted seismic sections of the Getic Depression foredeep; Analysis of outcrop- to regional-scale structures; Opening of WSW-ENE to E-W trending extensional basins; Dextral transpressive to transtensional movement within an E-W trending corridor.