Thermomechanical analogue modelling of the extensional collapse of a collisional orogeny the Svecofennian orogen, Finland

Nikkilä, Kaisa; Roy Chowdhury, Baishali; Dietl, Carlo; Korja, Annakaisa; Eklund, Olav; Zanella, Friedhelm


We present a set of analogue experiments simulating the extensional collapse of the Svecofennian orogeny. The experiments were conducted in a new thermomechanical deformation apparatus at Frankfurt University using plasticine as an analogue material. Layered models (upper crust, middle crust and lower crust) were constructed and subjected to extension mimicing the tectonic environment of Svecofennian orogeny, in which several crustal fragments accreted together following subduction induced continent-continent collision and subsequent extensional collapse. Intermittent magmatic phases attributed to the rise of temperature and subsequent migmatisation, which was aptly adapted in our models by incorporating high temperature phases during deformation. The models produced similar structures as described from the deep seismic reflection profiles BABEL and FIRE from the area.