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

Abstract

[1] Recent reconstructions 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.

Dynamic Topography and Ice Age Paleoclimate

“…They demonstrated, in particular, that long-wavelength, Cretaceous to Tertiary tilting of the Western Interior of North America was consistent with geologically inferred changes in the subduction history along the west coast of the continent (see also Lithgow-Bertelloni & Gurnis 1997). Similar arguments for subduction-(or subducted slab) controlled dynamic topography have been made to explain the stratigraphic record of the Russian Platform (Mitrovica et al 1996), the Taranaki Basin of New Zealand (Holt & Stern 1994), the Australian continent (Gurnis et al 1998, DiCaprio et al 2009, the Karoo Basin of southern Africa (Pysklywec & Mitrovica 1999), the Baltic Basin (Daradich et al 2002), northern South America (Shephard et al 2010), and Southeast Asia (Zahirovic et al 2016). Interactions between subducted slab material and the phase boundary at 670-km depth, which acts as a temporary impediment for flow into the lower mantle (Christensen & Yuen 1985), have also been identified as a mechanism for the development of transient intracontinental basins (Pysklywec & Mitrovica 1998)-for example, the Devonian to Carboniferous evolution of the Western Canada Sedimentary Basin (Pysklywec & Mitrovica 2000).…”