RODINIA TO GONDWANA: CONNECTIONS AND DISCONNECTIONS BETWEEN THE CRATONIC NUCLEI OF NORTH AND SOUTH AMERICA OBSERVED FROM PALEOMAGNETIC DATA

The tectonic activity of the Cordilleran margin of the North and South American continents is the most recent link in a chain of common geological events that have alternately connected and separated the cratonic nuclei of these continents. We trace the Precambrian paleogeographic history of the nuclei of these two continents (Laurentia and Amazonia) through the assembly of Rodinia and subsequent division during the opening of the Iapetus Ocean by evaluating the updated paleomagnetic database for South America (with Africa) for comparison with the established record for Laurentia. Reliable data are used to construct skeletal apparent polar wander paths (APWPs) that constrain the drift history for each craton. Our analysis supports a common drift history for Laurentia and the united Amazonia-West Africa craton (i.e. West Gondwana) beginning with the Grenvillian suturing in the late Mesoproterozoic. A separate drift history is observed for the “Central” Gondwanan cratons: São Francisco–Congo and the Kalahari, suggesting the continued existence of at least two separate tectonic plates separated by an ocean basin. The assembly of Central Gondwana: the Kalahari, São Francisco-Congo, and the Arabia-Nubian shield, by ca. 550 Ma was followed by the collision with West Gondwana by mid-Cambrian times, after the opening of the Iapetus ocean basin between Laurentia and Amazonia-West Africa. Geophysical and geological observations point to the existence of a suturing mobile belt between the cratons of Central and Western Gondwana. We present new paleomagnetic data from the Paraguai belt along the SE margin of the Amazon craton, which makes up part of this suture zone. These data point to interlimb rotations along a ca.600 km along-strike transect of the Paraguai belt, suggestive of the secondary origin for the curvature of this mobile belt. We postulate that this rotation was caused by differential accommodation of strain during the collision with the Central Gondwanan cratons, with partitioning between strike-slip dominated zones (parallel to the direction of convergence) and thrust-dominated domains (perpendicular to the direction of convergence). This event marks the final collision in the unification of Gondwana prior to the late Paleozoic assembly of the Pangea supercontinent.