3D MODEL OF THE DEEP STRUCTURE OF THE SVECOFENNIAN ACCRETIONARY OROGEN: A GEODYNAMIC INTERPRETATION

Abstract

The results of this study are reported in two related successive publications. The article “3D model of the deep structure of the Svecofennian accretionary orogen based on data from CDP seismic reflection method, MT sounding and density modeling” (M. V. Mints, E. Yu. Sokolova, LADOGA Working Group) presented a 3D model of the deep structure of the Late Paleoproterozoic Svecofennian accretionary orogen. The model is based on harmonized data of geological mapping, FIRE-2-2a-1 and FIRE-3-3a seismic reflection profiling, using sections of the 3D crustal density model, results of magnetotelluric surveys along the Vyborg-Suojarvi profile in the Northern Ladoga area and materials from MT surveys previously carried out by Finnish specialists in Southern Finland. In this paper these results were used as the baseline for the construction of the evolutionary model and determination of the position of the Svecofennian orogen in the structure and history of the Paleoproterozoic Lauro-Russian intracontinental orogen. This Paleoproterozoic orogeny swept the predominant part of Lauroscandia, a paleocontinent that united the North American and the East European cratons. Interpretation of the structural features and evolution of the Lauro-Russian orogen leads to the conclusion that its onset and evolution had a causative relation to the development of the Paleoproterozoic superplume which, in turn, initiated plate tectonic events. The evolution of the Lauro-Russian orogen included three intensive development periods (~2.5; 2.2–2.1 and 1.95–1.87 Ga). In the axial zone of the intracontinental orogen there appeared the Svecofennian Pre-Labrador Ocean, and the accretionary Svecofennian and Pre-Labrador orogens formed along its continental margins after its closure.