Paleo-Mesoproterozoic Supercontinents – A Paleomagnetic View

Lauri Pesonen, Satu Mertanen, Toni Henri Kristian Veikkolainen

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Sammanfattning

Various geological and geophysical evidence show that at least two supercontinents, Columbia and Rodinia, existed during the Paleoproterozoic and Mesoproterozoic eras. In this study, updated paleomagnetic and isotope age data has been used to define the amalgamation and break-up times of these
supercontinents. Before putting the ancient continents to a supercontinent assembly, we have tested the validity of the geocentric axial dipole model (GAD) of the Paleo-Mesoproterozoic geomagnetic field using four methods. The tests yield support to the GAD-model, but do not rule out a ca. 10% non-dipole
(octupole) field. In the whole of Proterozoic, Columbia and Rodinia were predominantly in moderate to low paleolatitudes, but during the Paleoproterozoic some parts of Columbia, notably India (Dharwar craton) and Australia (Yilgarn craton), occupied polar latitudes. In the Paleoproterozoic, there were unexpected low-latitude glaciations. The pre-Columbia orogenies were due to a complex set of collisions, rotations and transform or strike slip faultings that caused the orogenic belts to appear obliquely. No prominent difference was observed between paleomagnetically derived and recent geologic models of
Columbia. The final amalgamation of Columbia didn’t happen until ca. 1.53 Ga. Columbia broke up at ca. 1.18 Ga during several rifting episodes, followed by a short period of independent drift of most continents. The amalgamation of Rodinia didn’t take place until 1.10 – 1.04 Ga.
Originalspråkengelska
TidskriftGeophysica
Volym48
Utgåva1-2
Sidor (från-till)5-47
Antal sidor43
ISSN0367-4231
StatusPublicerad - 2012
MoE-publikationstypA2 Granska artikel i en vetenskaplig tidskrift

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