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The kinematic models proposed for the Tertiary evolution of the Romanian Carpathians explain its arcuate shape by the progressive displacement of the upper plate (Tisza-Dacia block) around the western margin and then along the northern margin of Moesia, the latter representing the stable foreland autochthon. The main tectonic events took place in the Eocene when a former nappe pile, formed by the end of the Cretaceous and representing the actual Southern Carpathians, underwent extension. This episode was followed by dextral wrenching that was accompanied by the opening of the Getic Depression as a pull-apart basin along the northern Moesian margin, at the current location of the Southern Carpathian foothills. This deformation operated from Oligocene to Lower Miocene times. Although from the Lower Miocene onwards the progressive eastwards motion of the Tisza-Dacia block accounted for well-defined accommodating structures in both the frontal (Eastern Carpathians) and lateral (Getic Depression) sides of the accretionary wedge, the Eocene to Lower Miocene tectonics left apparently no imprint upon the outer thin-skinned belt. We have looked for the sedimentary records of these tectonic events by building and integrating several detailed sedimentary logs near the contact between the Outer Carpathians and Moesia. Two main facies associations were defined in terms of basin energy, i.e. proximal high-energy prograding associations, represented by coarser sedimentary units and distal variable-energy aggrading associations. Based on the wide incision observed at the base of the high-energy units and on the clast provenance, we assume a tectonic origin for the vertical changes observed in the dipping attitude of the beds, which account for angular unconformities. Importantly, the regional correlation of the Eocene-Lowermost Miocene formations points to a progressive migration in time and space of the high-energy sedimentary units, which get younger eastwards, consistent with the direction of the tectonic transport of the Carpathian allochthon. Les modèles cinématiques proposés pour l’évolution des Carpathes roumaines au Tertiaire expliquent la forme arquée de cette chaîne de montagnes par le mouvement de la plaque supérieure (bloc de Tisza-Dacia) autour de la marge occidentale, puis le long de la marge septentrionale de la Moésie, cette dernière représentant l’avant-pays de la chaîne et le substratum de la partie méridionale du bassin flexural. Les principaux événements tectoniques sont survenus pendant l’Eocène quand l’ensemble chevauchant (formé vers la fin du Crétacé et représentant les Carpathes méridionales actuelles) a subi une extension. Cet épisode a été suivi d’une translation décrochante dextre accompagnée de l’ouverture de la Dépression Gétique en bassin de pull-apart sur la marge septentrionale de la Moésie (en termes géographiques, le piémont des Carpathes méridionales). La deuxième déformation s’est déroulée pendant l’intervalle Oligocène- Miocène inférieur. Même si, à partir du Miocène inférieur, l’avancement progressif du bloc Tisza-Dacia vers l’est a induit des structures assez bien définies dans la zone frontale du prisme tectonique (Carpathes orientales) et sur sa bordure latérale (Dépression Gétique), la tectonique de l’Eocène-Miocène inférieur n’a apparemment laissé aucun signe de déformation sur la ceinture déformée externe. Nous avons recherché des marqueurs tectoniques de cet intervalle de temps en construisant et intégrant des colonnes sédimentaires détaillées dans la zone du contact entre les Carpathes externes et la Moésie. Deux catégories principales d’associations de faciès sédimentaires ont été définies en termes d’énergie de dépôt : des associations proximales progradantes de haute énergie représentées par des unités sédimentaires plus grossières et associations distales aggradantes d’énergie variable. Une origine tectonique (syn-cinématique) des unités de haute énergie est envisagée grâce à l’érosion significative observée à leur base, la provenance des grains détritiques et les pendages des couches indiquant en général des discordances angulaires. Une conclusion importante est que la corrélation régionale des formations d’âge Éocène-Miocène basal indique une migration progressive spatiale et temporale des unités sédimentaires de haute énergie qui deviennent plus jeunes vers l’est, en accord avec la direction du transport tectonique de la plaque supérieure du système carpathique.

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.