A cross-section through the Zilair Nappe (southern Urals)

A structural transect in the Zilair-Kugarchi area involves the western part of the Suvanyak Complex, the Zilair Nappe and the eastern part of the foreland thrust and fold belt. This section has been analyzed using field, microstructural and seismic data. The cross-section shows the transition from the hinterland to the foreland in the footwall to the suture of the southern Urals. The rocks involved range from early Palaeozoic to Permian in age. A characteristic of the Zilair Nappe is the dominance of a succession of volcanic greywackes and mudrocks of Late Devonian age (Zilair Formation). The metamorphic grade decreases from east to west, from greenschist facies to diagenetic conditions. The structure of the cross-section mainly comprises west-directed thrusts and thrust-related folds with an associated cleavage. Fold vergence changes along the section depending on of the distance to the associated thrust and its geometry. The Zilair thrust which separates the Zilair Nappe from the foreland thrust and fold belt accommodated ca. 10 km displacement and the characteristics of the deformation are similar on both sides of it. The contact between the Zilair Nappe and Suvanyak Complex is a west-dipping normal fault that does not represent a major tectonic boundary.