Master of Science Marina Galindos Alfarache will Friday June 5th, 2026, at 12:15 hold her Thesis Defense for the PhD degree in Science. The title of the thesis is:
« Metamorphic and (micro)structural evolution of the Lyngen Magmatic Complex »
The oceanic and lower continental crust are of mafic composition. Understanding the deformation mechanisms involved during the exhumation of mafic rocks is critical to constrain crustal rheology. This thesis focuses on the deformation of the mafic rocks of the Lyngen Magmatic Complex (LMC), an ophiolitic body from the North Norwegian Caledonides. The results are divided into two blocks, addressing the macro-/ meso- and microstructural deformation of the LMC based on field observations and sampling. New structural, geochemical, thermobarometric, and geochronologic data provide a new interpretation of the tectono-metamorphic evolution of the LMC, leading to a new model for the regional evolution of the North Norwegian Caledonides. Two deformation events are identified at 486 Ma (D1, pre-Scandian) and ~ 426 Ma (D2, Scandian), and an out-of-sequence nappe assemblage during the Scandian orogenic event. It is concluded that fluid-rock interactions facilitate rock deformation, locally obliterating previous fabrics. The microstructural analyses focus on the mechanisms involved in the interaction between deformation and fluid-assisted syn-deformational retrograde reactions. Dissolution-precipitation creep is identified as the dominant deformation mechanism facilitating the reconstitution of medium- to low-temperature phases like actinolite or (clino)zoisite. These phases grow in the stretching direction, developing grains with high aspect ratios, and strong shape and crystallographic preferred orientations. These features and grain size reduction facilitate strain localization and mechanical weakening of the rock. The results in this thesis evidence the relation between micro- and macrostructural deformation and the impact of reaction-assisted deformation on the rheological evolution of large mafic bodies (e.g., the oceanic crust).
1st Opponent: Associate professor Laura Airaghi, Institut of Earth Sciences of Orléans, University of Orléans, France
2nd Opponent: Professor Deta Gasser, Department of Civil Engineering and Environmental Sciences, Western Norway University of Applied Sciences
Internal member and leader of the committee: Associate professor Carly Faber, Department of Geosciences, UiT, Norway