BLIND DUPLEX STRUCTURE OF THE NORTH URALS THRUST BELT FRONT

Abstract

New multichannel seismic-reflection profiles shot across the north Ural thrust front indicate the presence of previously unknown wedge-shaped foreland-verging blind duplex. The structure of this zone shows westward thrusting of the tectonic wedge of the Silurian-Artinskian assemblage into the foreland sedimentary cover. This process caused structural delamination of the basin succession, tilting of frontal molasse monocline above the leading edge of the low-taper allochthonous unit, thrust duplication and tectonic thickening of the wedge. Two distinct structural styles are recognized in the blind thrust. Its frontal zone formed by Artinskian shale has thin-skinned imbrication structure. The eastern internal zone consists of Silurian-Sakmarian carbonate-dominated sequences that have much more coherent thrust and fold deformations. This part of allochthonous unit forms a rigid “core” of the blind duplex. The structural geometry of the study area suggests its tectonic shortening of at least 60 km.