Breaking the Grenville–Sveconorwegian link in Rodinia reconstructions

Abstract

The Grenville, Sveconorwegian, and Sunsas orogens are typically inferred to reflect collision between Laurentia, Baltica, and Amazonia at ca. 1.0 Ga, forming a central portion of the Rodinia supercontinent. This triple-junction configuration is often nearly identical in otherwise diverse Rodinia reconstructions. However, available geological data suggest that although the Grenville and Sveconorwegian provinces shared a similar tectonic evolution from pre-1.8 to ca. 1.5 Ga, they record distinctly different tectonic histories leading up to, during, and possibly following Grenville– Sveconorwegian orogenesis. Moreover, paleomagnetic data suggest the two continents were separated at peak orogenesis, further invalidating any direct correlation. A number of possible interpretations are permissible with available geological and paleomagnetic data, of which a ‘classic’ triple-junction configuration appears least likely. In contrast to the commonly inferred intertwined Proterozoic evolution of Baltica and Laurentia, the possibility remains that they were unrelated for a billion years between 1.5 and 0.45 Ga.