Abstract The Alps and Western Carpathians constitute that part of the Alpine-Mediterranean orogenic belt which advances furthest to the north into Central Europe. They were formed by a series of Jurassic to Tertiary subduction and collision events affecting several Mesozoic ocean basins, continental margins, and continental fragments. The Western Alps form a pronounced, westward-convex arc around which the strike of the tectonic units changes by almost 180° ( Fig. 18.1 ). The Western Carpathians are a northward-convex arc of similar size but with minor curvature. The two arcs are connected by an almost straight, WSW-ENE striking portion including the Eastern Alps Stresses produced by tectonic processes in the Alps also influenced the tectonics of large parts of central and northern Europe, leading, for example, to basin inversion and strike-slip faulting. In this chapter, we will discuss the present-day structure of the different tectonic units in the Alps and Western Carpathians in relation to their palaeotectonic history in order to illustrate the plate tectonic evolution using geological data. Many tectonic problems of the Alps and Western Carpathians are still unsolved, although dramatic progress has been made, especially over the last c. 20 years. Therefore, some of the interpretations presented below are still controversial and do not always express the opinion of all three authors. Given that the main theme of this book is Central Europe, the Southern and Western Alps are discussed in less detail than those parts of the Alps which belong to Central Europe: the Central Alps, the Eastern Alps and the Western Carpathians.

Abstract The Cenozoic tectonic evolution of Central Europe was governed over long periods of time by far-field stresses resulting from continent collision in the Alps (which is still ongoing) ridge push in the Atlantic Ocean, and other sources. Such far-field stresses interfered with more local stresses related to processes such as the rise of mantle plumes, leading to the Cenozoic volcanism of Central Europe, and glaciation. Alpine tectonics north of the Alps began with the effects, of Late Cretaceous_Early Palaeogene continent collision in the Pyrenees, on the European crust. During Tertiary times, the stress field was unstable and repeatedly changed both in terms of magnitude and orientation. Notably, an episode of ESE-WNW to east-west directed extension during the late Eocene to Oligocene created the European Cenozoic Rift System (Rhône-Bresse Graben, Upper Rhine Graben, Lower Rhine Basin, and others) which up to the present is tectonically the most active zone of Central Europe. Flexural basins formed in the southernmost part of the Alpine-Carpathian foreland. The Jura Mountains also form part of the Alpine foreland, although they could, from a tectonic point of view, also be regarded as part of the Alps. They represent the most external foreland fold-and-thrust belt of the Alps. Folding and thrusting in the Jura Mountains took place during the Middle Miocene to Pliocene, and the thrust front presently propagates northward into the Upper Rhine Graben. The Alpine tectonics of southern Germany may best be described in terms of reactivation of older inherited, mainly Variscan, basement structures. This is also the case for the central Leine Graben, the Harz Mountains and parts of the North German Basin. Because of the frequent reactivation of faults, the following sections include some remarks on pre-Alpine deformation and sedimentation history. The general episodes of Alpine deformation north of the Alps can be subdivided into three main phases: (1) the period of Late Cretaceous-Early Palaeogene inversion tectonics, when far-field effects of continent collision and the formation of the Pyrenees resulted in deformation extending as far north as the Danish North Sea, including the large-scale uplift of the Harz Mountains; (2) Eocene to Miocene extensional tectonics with the formation of large graben systems, for example the Upper Rhine Graben; and (3) the phase of tectonics related to the reorganization of the stress field during the Late Miocene, which coincides with the initiation of the ‘neotectonic period’ and the present-day stress field in Central Europe, which is characterized by SE-NW compression and NE-SW extension. The Neogene to recent evolution of northern Central Europe, including the North German Basin and the Polish Basin, which are parts of the Central European Basin System, was partly affected by glacial loading and unloading during the Pleistocene. Presently, these regions are areas of low seismicity (macroseis mic intensities III-IV EMS; Grünthal & Mayer-Rosa 1998 ). Major stresses acting within the North German Basin and the Polish Basin were induced by the North Atlantic ridge push forces (east-west, or NW-SE directed), the ongoing Alpine collision (north-south directed), and, from the late Pleistocene onwards, the post-glacial rebound of Fennoscandia (mainly vertical, but also with a horizontal, west-east directed component). Present-day maximum horizontal stresses within the North German Basin are generally directed NW-SE ( Rockel & Lempp 2003 ), but fan and bend towards the NNE, north of 52°N and east of 11°E, especially in the Polish Basin. The present-day stress field in the Central European Basin System is influenced by the decoupling of two crustal units ( Roth & Fleckenstein 2001 ), which are separated by Zechstein evaporites (the Pre Zechstein formations together with the older units are decoupled from the overlying Mesozoic and Cenozoic sediments). The general stress orientation, with NE-SW maximum horizontal stress, was regionally modified or disturbed ( Rockel & Lempp 2003 ). In areas of salt movement and the formation of salt pillows, salt walls and diapirs, the resultant local increase or decrease in salt thickness had a marked effect on stresses and tectonic structures (e.g. in the western Baltic Sea ( Hansen et al. 2005 ) and in the Gliickstadt Graben area ( Maystrenko et al. 2005 ). Major basement faults within the intracratonic Central European Basin System are orientated NW-SE, while minor faults trend NE-SW and NNE-SSW, and are clearly visible in shaded relief and satellite images ( Reicherter et al. 2005 ). The northern rim of the Central European Basin System is bounded by the Tornquist Zone, which consists of the Teisseyre-Tornquist Zone from Poland to Bornholm Island, and the Sorgenfrei-Tornquist Zone from southern Sweden to Denmark ( Fig. 19.1 ). Additionally, the drainage pattern and the distribution of lakes in northern Germany parallel the block boundaries and, hence, mark zones of present-day subsidence ( Mörner 1979 ; Stackebrandt 2004 ; Reicherter et al. 2005 ). A broad zone of subsidence extends from Hamburg to Berlin and onto Wroclaw (Poland) and is delineated by the depth to the base of the Rupelian Clay (Oligocene; Garetzky et al. 2001 ). This zone shows relatively minor faulting in the near-surface layers. The depocentre axes also had a NW-SE trend during the Mesozoic.

Abstract During Europe–Adria collision in Tertiary times, the Monte Rosa nappe was penetratively deformed in several stages after an eclogite-facies pressure peak: (1) top-to-the-NW thrust shearing (Mattmark phase, after 40 Ma); (2) orogen-parallel, top-to-the-SW extensional shearing and folding (Malfatta phase); (3) orogen-perpendicular, top-to-the-SE extensional shearing and folding (Mischabel phase, before 30 Ma); and (4) large-scale, upright, SE-vergent folding (Vanzone phase, c . 29–28 Ma). Structural analysis and neutron texture goniometry of quartz mylonites show that the Stellihorn shear zone in the Monte Rosa nappe accommodated a complex and multidirectional sequence of shearing movements during the Mattmark, Malfatta and Mischabel phases, and was folded in the Vanzone phase. In the tail-shaped eastward prolongation of the Monte Rosa nappe in the Southern Steep Belt of the Alps, both dextral and sinistral mylonites (Olino phase) were formed during and after the formation of the Vanzone fold, reflecting renewed orogen-parallel (SW–NE) extension contemporaneous with NW–SE shortening from c . 29 Ma onward. A similar sequence of deformation stages was identified in the Adula nappe at the eastern border of the Lepontine metamorphic dome. Important consequences arise for the Insubric fault at the southern border of the Lepontine dome: (1) the NW- to N-dipping orientation of the Insubric fault is not a primary feature but resulted from rotation of an originally SE-dipping shear zone after c . 30 Ma; and (2), the strong contrast in metamorphic grade across this fault (upper amphibolite facies to the north versus anchizone to the south) results from north-side-up faulting coupled with orogen-parallel extension of the northern block (Lepontine dome), while no such extension occurred in the southern block (Southern Alps). Extension in the northern block started in the Malfatta phase and continued in the Mischabel phase when the foliation in the area which later became the Southern Steep Belt still dipped towards south. During Vanzone/Olino deformation, further unroofing and uplift of the Lepontine dome relative to the South Alpine block took place while the Southern Steep Belt was progressively rotated into its present, overturned position, changing its character from a normal fault into a backthrust. Complex deformation paths in the Southern Steep Belt resulted from the combination of extension of the northern block with strike-slip motion along the Insubric fault.