Estimation of crustal thinning by accounting for stretching and thinning of the sedimentary basin — An example from the Vøring margin, NE Atlantic

We propose a simple analytic way to estimate the β- (stretching) factors for basin formation by lithospheric extension. The suggested approach accounts for the stretching and thinning of the sediments in a mass conservative manner. It is shown that the stretching and thinning of the sediments may have an important impact on the magnitude of the β-factors, especially for deep basins with thick pre-rift formations. This mass conservative way to estimate β-factors has been applied to a transect on the Atlantic Vøring margin offshore mid-Norway, where it undergoes four rift episodes from the end of the Caledonian orogeny until today. The results for the Vøring transect show that the first rift phases may have been more important than previously modeled. These results also show that the magnitude of the Late Cretaceous–Paleocene rift phase becomes reduced by including extension and thinning of pre-rift sediments. The analytic results allow for a study of the sensitivity of the β-factors with respect to various parameters like for instance paleo water depth and rock densities.