The controlling parameters of the structural style in the Oslo-Asker section: A field and analogue modeling study

Abstract

The foreland basin situated in the Oslo area is comprised of Paleozoic sediments that are deformed during the Caledonian orogeny. A structural model for the development of this basin is proposed by Bruton et al. (2010) but it lacks detailed structural field data to support the model. Building further on this model we performed a kinematic field study and analogue modeling to increase the understanding of the Caledonian history of the Oslo area. An 8 km N-S profile has been constructed in the Slemmestad area which showed a transition in structural style from dominant foreland directed thrusting in the south to hinterland directed thrusting in the middle and folding in the north. The entire Slemmestad are shows a dominant top to the SE transport direction with a 60/10 fold axis. The main controlling mechanism for the difference in structural style is the difference in lithology with the ratio of limestone to shale becoming higher from south to north. Interpreting the field data from the Slemmestad area in terms of deformation style shows a good match with the model from Bruton et al. (2010). The analogue models show deformation structures that are also found in the field and are therefore a good addition to strengthen the support of the model from (Bruton et al. 2010).