Paleogeographic settings and tectonic deformations of the Barents Sea continental margin in the Cenozoic

Abstract

The Barents Sea continental margin (hereafter, Barents margin) differs from other passive margins by the most extensive shelf, the giant thickness of sedimentary rocks in basins and troughs, and its unique tectonic position. The outer, almost rectangular promontory of the Barents margin juts out into its deepwater western and northern framing (Fig. 1), identified as the Norwegian‐Greenland and Eurasia basins, respectively. In this regard, the continental margin is affected by two, mutually perpendicular spreading zones (Knipovich and Gakkel ridges). The evolution of oceanic basins proceeded in the course of continuous tectonic and geodynamic interaction with the framing continental margins. In our case, this was expressed, first of all, in the separation and evolution of the Barents Sea shelf platform as an area of neotectonic transformations during the opening of young oceanic basins. Its structures were transformed against the background of breakup and block-shaped disintegration (destruction and fractalization) of the continental crust. This is indicated by Cenozoic volcanism in the Spitsbergen and Novaya Zemlya segments, development of tectonomorphic trenches (grabens), anomalous geophysical properties of the present-day Earth’s crust (including thermal and seismic activity), and specific deformations of the sedimentary cover. All the aforementioned allow us to make a judgement about the contribution of the Cenozoic ocean formation to the modern tectonics and architecture of the Barents margin. The initial breakup of the joint continental lithosphere located between the Barents margin, on the one hand, and Greenland and Lomonosov protoridge, on the other, most likely occurred in the region of the future divergence of plates during the Late Cretaceous‐ Early Paleocene. This is indicated by marine drilling and seismic profiling data suggesting that geological history of the Barents margin included a very important erosion and denudation phase related to the regional uplift before the rift stage. The amount of the material removed from only the inner shelf during the Cenozoic is estimated at 1.5‐2.0 km [1, 2]. In the peripheral zones adjoining the intercontinental rift systems in the Late Cretaceous‐Early Paleogene, the amount of eroded material increases to 3 km or more. However, up to one-half of the material was eroded by glacial processes.