Mantle flow modeling of the anomalous subsidence of the Silurian Baltic Basin

Abstract

Recent reconstruction of the Silurian Baltic Basin indicate a long-wavelength component of sediment deposition. This deposition extends over 400 km beyond basins predicted on the basis of supracrustal loading in the region; it has been suggested that the discrepancy may be due to dynamic topography associated with mantle flow linked to Silurian plate subduction under Baltica. We test this suggestion using mantle convection simulations, and find that dynamic topography is capable of reconciling the anomalous far-field deposition. These simulations constrain the paleo-dip of the subduction to 40°-60°, with the range reflecting an uncertainty in the location of the paleo-trench. We furthermore demonstrate that this mantle loading component provides 40-85% of the reconstructed near-field deposition. This result indicates that the slab-induced mantle flow mechanism is a potentially important contributor to the development of the foreland basin, and that previous estimates of the 'orogenic' (i.e., supracrustal) load associated with plate convergence may have been overestimated.