Horizontal Movements in the Eastern Barents Sea Constrained by Numerical Models and Plate Reconstructions

The eastern Barents Sea basins, west of Novaya Zemlya, were mildly inverted between Late Permian and Early Jurassic times, as indicated by mild folds in the basin sediments. Previous studies have suggested that the crustal part of Novaya Zemlya was thrust westward, but the magnitude of this compressive movement is not well known. Our aim is to provide an order-of-magnitude constraint on the amount of shortening associated with the displacement of Novaya Zemlya and the inversion of the eastern Barents Sea basins by combining numerical models and plate reconstructions in an iterative process. We use a 2D thermo-mechanical finite-element method to model inversion of a predefined basin. The total amount of shortening imposed on the models is first constrained by plate reconstructions for the Barents Sea region for the late Paleozoic to early Mesozoic. We assume that the shortening was caused by westward movement of the Siberian plate, but the magnitude of this westward displacement in plate reconstructions is highly uncertain due to the allochthonous nature of the rocks of Novaya Zemlaya and the scarcity of palaeomagnetic data in the region. Our models show that shortening localizes in the model basin and at Novaya Zemlya and that westward propagation of deformation is more efficient when the strength of the lower crust is reduced. By comparing the inversion obtained in the numerical models to the inferred inversion structures in the eastern Barents Sea basin we further constrain the amount of shortening that caused the inversion and therewith improve the plate reconstructions for the region. Our models indicate that the westward movement of Novaya Zemlya occurred in the Late Triassic-Early Jurassic (220-190 Ma) and was limited in magnitude to 100-200 km, which is considerably less than previous estimates (500-700 km).