Tectonic Evolution of the Svecofennian Crust in Southern Finland
Tectonic evolution of the Svecofennian crust in southern Finland – a basis for characterizing bedrock technical properties Edited by Matti Pajunen Geological Survey of Finland, Special Paper 47, 15–160, 2008. TECTONIC EVOLUTION OF THE SVECOFENNIAN CRUST IN SOUTHERN FINLAND by Matti Pajunen*, Meri-Liisa Airo, Tuija Elminen, Irmeli Mänttäri, Reijo Niemelä, Markus Vaarma, Pekka Wasenius and Marit Wennerström Pajunen, M., Airo, M.-L., Elminen, T., Mänttäri, I., Niemelä, R., Vaarma, M., Wasenius, P. & Wennerström, M. 2008. Tectonic evolution of the Svecofennian crust in southern Finland. Geological Survey of Finland, Special Paper 47, 15–160 , 53 figures, 1 table and 9 appendices. The present-day constitution of the c. 1.9–1.8 Ga old Svecofennian crust in south- ern Finland shows the result of a complex collision of arc terranes against the Ar- chaean continent. The purpose of this study is to describe structural, metamorphic and magmatic succession in the southernmost part of the Svecofennian domain in Finland, in the Helsinki area. Correlations are also carried out with the Pori reference area in southwestern Finland. A new tectonic model on the evolution of the southern Svecofennian domain is presented. The interpretation is based on field analyses of structural successions and magmatic and metamorphic events, and on interpretation of the kinematics of the structures. The structural successions are linked to new TIMS and SIMS analyses performed on eight samples and to published age data. The Svecofennian structural succession in the study area is divided into deforma- tion phases DA-DI; the post-Svecofennian events are combined as a DP phase. Kinemat- ics in the progressively-deforming transtensional or transpressional belts complicates analysis of the overprinting relations due to their simultaneous contractional and exten- sional structures.
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