8.5.2025
Doctoral thesis on the evolution of the bedrock, especially migmatites and associated rocks, in southwestern Finland
M.Sc. Jon Engström’s doctoral thesis in geology and mineralogy will be put forth for public defence at the Faculty of Science and Engineering at Åbo Akademi University.
The thesis is entitled From local constraints to regional perspectives – Tectonic evolution during the late stages of the Svecofennian orogeny in southwestern Finland.
The public defence of the doctoral thesis takes place on 16 May 2025 at 1PM in Auditorium 1, Geologicum, Tuomiokirkontori 1, Turku. Professor Atle Rotevatn, University of Bergen, Norway, will serve as opponent and Professor Olav Eklund, Åbo Akademi University, as custos.
Summary
This study explores the evolution of the bedrock, especially migmatites and associated rocks, in southwestern Finland through structural geological mapping in micro- and meso-scale, combined with pressure-temperature modelling and age determinations using the following minerals zircon, garnet and apatite.
The site of the study is mainly the Olkiluoto area in southwestern Finland, that has preserved the geological and tectonic history well. The Olkiluoto site is where the deep geological repository for spent nuclear fuel in Finland will be located. Therefore, this site fits well for this research since extensive data concerning the bedrock and geological structures already exist.
Investigation of a nearby ductile shear zone, the Kynsikangas Shear Zone, provides information on the crustal-scale deformation regime during the Svecofennian orogeny. The study explores similarities between the Häme Belt in Finland and the Ljusdal lithotectonic unit in central Sweden. The result of the study defines that the Ljusdal lithotectonic unit and Häme Belt have been tectonically connected in the past.
Jon Engström was born in 1976 in Turku, Finland. He can be reached by email jon.engstrom@gtk.fi.
The doctoral thesis can be read online through the Doria publication archive.