Alpine cover nappes are usually characterized by both folding and stretching, suggesting simple shear between two comparatively rigid plates: subducted basement below and an “orogenic lid” above with its frontal wedges. The lid consists of thrust masses piled up in earlier stages which, being cooler and stronger due to previous deformation, constitute a comparatively rigid body. Basement nappes are formed in a variety of modes. They may emerge as steeply dipping lobes into the shear zone and there flatten out; in this case, they develop from highly “viscous” masses at elevated temperature in a sort of distributed ramp under oblique compression. In other cases, they are sheared off from their crustal underpinnings and move as rigid bodies: a famous example is the Austroalpine Silvretta nappe. At its base, widespread mylonites are in some places interrupted by pseudotachylites. These are interpreted as due to stress concentration followed by explosive failure in patches that resisted creep. In the Early Tertiary, nappes generally moved north with respect to Europe, but at a late stage there was considerable backflow toward Africa. This may be due to arrival of the North Penninic subplate boundary in the subduction zone.

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.