The Cambrian pre-Uralide-Timanide orogen: Structural evidence for its collisional origin

Abstract

At present, there are two alternative standpoints on the northeastern fringing of the Late Precambrian– Early Paleozoic evolution of the East European Platform: accretionary and collisional. According to the accretionary concept [1], the Timan margin of the Baltia continent (Precambrian framework of the East European Platform) successively amalgamated island arcs, microcontinents, relicts of basins underlain by the oceanic crust, and other structures. Contrary to this concept, other researchers, myself included, share the collisional hypothesis, according to which the Precambrian–Cambrian transition was marked by collision between the Late Precambrian Timan passive margin of the Baltia continent with the Bolshezemel’skaya active margin of the Arctida continent [2]. The Pechora– Ilych–Chiksha zone of faults traceable in the basement of the Pechora Plate and its continuations in the Barents Sea shelf and Kvarkush Anticlinorium in the Urals represent a relict of the collisional suture (Fig. 1). The main structural consequence of collision was the formation of the Cambrian collisional divergent orogen of pre-Uralides–Timanides, the axial part of which is marked by the suture. The southwestern limb of the orogen is largely composed of dislocated sedimentary complexes of the Late Precambrian passive margin of the Baltia continent, which were thrust over its adjacent areas, while the northeastern limb is mostly represented by complexes of the Bol’shezemel’skaya active margin of Arctida and its rear zones that were involved into large-amplitude overthrust displacements toward the latter. This communication is dedicated to structural analysis of relict complexes formerly constituting the pre-Uralides–Timanides of the Timan– Pechora–Barents Sea region and neighboring areas (Fig. 2). Relicts of the southwestern limb of the orogen. The structural paragenesis of pre-Uralide–Timanide complexes constituting the southwestern limb of the orogen has been studied in the Varanger, Srednii, and Rybachii peninsulas. Some information on the structure of the pre-Uralides–Timanides in the southwestern limb of the orogen can be derived from the structural analysis of the Kanin Kamen Range and the near-Timan part of the Pechora Plate basement based on seismic materials. In all these areas, the pre-Uralide–Timanide complexes are characterized by a distinct southwestern vergence of fold–thrust dislocations and the approximately NW– SE strike of mesostructural linear elements (hinges of different-scale asymmetrical folds, mineral and deformation-related linearity).