Deep crustal structure and Palaeoproterozoic evolution of the supercontinent Lauroscandia: 3D model of Trans-Hudson Orogen and new insight based on LITHOPROBE, FIRE and 1-EU reflection seismic and HuBLE tomography imaging

Abstract

The Palaeoproterozoic Lauroscandia supercontinent received fundamental geological and geodynamic support based on the 3D characteristics of the deep structure of key tectonic units in the North American and East European megacratons. The deep structure of the western Reindeer zone of Trans-Hudson orogen (THO) most closely resembles the structure of sedimentary–volcanic belts along the eastern boundary of the Karelia craton formed during continental rifting. These belts were accompanied by vast depressions filled by the thick epicontinental volcano-sedimentary sequences, which were later affected together with the Archaean basement by high-temperature metamorphism. Some of the rifts could later be transformed into narrow short-lived oceans. The deep structure of the eastern Reindeer zone of THO is similar to Svecofennian accretionary orogen: structures of the crust and crust-mantle boundary point to a significant breakup of the continent, the origin of an ocean, and its later closure, involving a number of subduction zones, which operated almost simultaneously. The Sask craton should be viewed as a fragment of a Neoarchaean megacraton of North America. The main feature of the THO, Svecofennian Accretionary Orogen and Lauroscandia as a whole during Palaeoproterozoic evolution is the causal link with development of the Hudson Bay superplume that initialized a succession of huge events of plate-tectonic type. The head of the Hudson Bay superplume reached about 3000 km in the north-south direction and from 3000 to 4500 km in the east-west direction at different stages of evolution; 4500 km likely is a minimal estimate of the greatest dimension. The width of the Manikewan ocean reached more 1000 km, the width of the Svecofennian–Pre-Labradorian Ocean of ~2000 km that apparently also corresponds to a minimal value. The most significant temporal intervals in the Lauroscandia Palaeoproterozoic evolution (~2.5 Ga and 2.2–1.8 Ga ago) coincide with events of global rank.