Forward modeling of stretching episodes and paleo heat flow of the Vøring margin, NE Atlantic

Abstract

Abstract The rift evolution of the Voring margin (west of mid-Norway) and the corresponding paleo heat flow have been modeled with new seismic data for a Voring transect. Especially the improved mapping of the crust and the horizons in the basin provides better constraints for the modeling. The modeling of the stretching episodes is based on a reconstruction of the Permian crust using the present day crustal thickness and the present day tectonic subsidence, and its thickness is found to be in the range of 27–37 km. The stretching ( β ) factors have been calibrated in order to match the present day crustal thickness, and also the present day tectonic subsidence. We found the stretching ( β ) factors to be somewhat larger than previously reported, which may be due to a thinner crust in this study than in earlier studies. The β factors for each rift episode show basin migration along the transect (from east towards the west). The radioactive heat generation in the crust and the sediments are calibrated to reproduce heat flow in the range of observed values, and its average value is found to be ∼ 1.3 μ W m−3. The heat flow modeling shows that the Late Jurassic stretching episode creates an increased basin heat flow that lasts until mid-Cretaceous. The deposition of the thick formations starting at mid-Cretaceous leads to a noticeable depression of the basin heat flow that lasts until the Paleocene. A similar depression of the basin heat flow is also found from the deposition of the Pliocene and Pleistocene sediments. The modeling also shows that the reduction in the heat flow from crustal thinning is to a large degree compensated by the heat generation from the sediments. Heat generation in the sediments explains the lack of large variations in the surface heat flux along the transect, although there are substantial variations in the crustal thickness. The steady state mantle heat flux is estimated to be 30 mW m−2, which is roughly half the surface heat flux. The other half of the heat flux is due to heat generation in the crust and in the sediments.