The late Oligocene‐Miocene tectonic style of the Alps is variable along strike of the orogen. In the Western and Central Alps, foreland imbrication, backthrusting, and backfolding dominate. In the Eastern Alps, strike‐slip and normal faults prevail. These differences are due to lateral extrusion in the Eastern Alps. Lateral extrusion encompasses tectonic escape (plane strain horizontal motion of tectonic wedges driven by forces applied to their boundaries) and extensional collapse (gravitational spreading away from a topographic high in an orogenic belt). The following factors contributed to the establishment of lateral extrusion in the Eastern Alps: (1) a rigid foreland, (2) a thick crust created by indentation and earlier collision, (3) a decrease in strength in the crust due to thermal relaxation, (4) a crustal thickness gradient from the Eastern Alps to the Carpathians, and, possibly, (5) a disturbance of the lithospheric root. Northward indentation by the Southern Alps causes thickening in and in front of the indenter and tectonic escape. Gravitational spreading attenuates crustal thickness differences. Indentation structures occur in the western Eastern Alps and comprise folds, thrusts, and strike‐slip faults. These structures pass laterally into spreading structures, which encompass transtensional and normal faults in the eastern Eastern Alps. The overall structural pattern is dominated by escape structures, namely, sets of strike‐slip faults that bound serially extruding wedges. Structural complexity arises from (1) interference of major fault sets, (2) accommodation of displacement differences between the Eastern Alps and their fore‐ and hinterland, (3) displacement transfer from the Eastern Alps toward the Carpathians which act as a lateral unconstrained margin, and (4) crustal decoupling, which partitions extrusion into brittle upper plate and ductile lower plate deformation. The kinematics of lateral extrusion is approximated by an extrusion‐spreading model proposed for nappe tectonics.

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Field studies in the Romanian South Carpathians (longitude 22.5° to 24.2°E and latitude 45.2° to 45.6°N) demonstrate (1) Cretaceous top‐to‐NE shearing parallel to the present strike of the thrust system connected with coaxial flattening within the generally northwest dipping foliation, (2) Paleogene ductile‐brittle dextral wrenching, E‐W compression (σ1: 87±15°), and basin formation (Petroşani basin) along the Cerna‐Jiu fault system, (3) large‐scale Miocene dextral wrenching along the northern margin of Moesia (σ1: 143±16°), and (4) probably Pliocene–early Pleistocene N‐S compression (σ1: 205±25°). We discuss the tectonics of the South Carpathians stressing the corner effect of the Moesian foreland promontory during convergence and formation of the Carpathian orocline. Up to the late Early Cretaceous, subduction of oceanic crust was active between Europe‐Moesia on one side and East Carpathia‐Rhodopia on the other side. Collision and intracontinental deformation occurred during the late Early and Late Cretaceous. The pinning of the thrust front at the western tip of Moesia and the foreland recess north of it caused superposition of thrusting and wrenching during collision and lateral translation, tangential stretching during orocline formation, and spreading into the recess. Further convergence during the early Tertiary resulted in dislocation of the previously welded East Carpathian‐Rhodopian and Moesian fragments along the Cerna‐Jiu fault system and the further northeast translation of the western segment. The intramontane Petroşani basin opened as a northeasterly propagating, transient pull‐apart structure along the Cerna‐Jiu fault system, which acquired a curved, northwesterly convex, transtensional trace due to the shape of the Moesian promontory. Tightening of the Carpathian orocline and/or rearrangement of the microplate geometry during the formation of the Pannonian basin system led to large‐scale dextral wrenching along the northern margin of Moesia. Pliocene N‐S compression reflects final shortening in the Carpathian system before ongoing convergence between Europe and Africa was transferred to the Mediterranean. Rotation of material lines around the Moesian corner is corroborated by paleomagnetic studies.

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