Continental tapering of South America caused asymmetric non-uniform opening of the South Atlantic Ocean

Abstract

South Atlantic opening has been typically modelled as being related to symmetric and static thermal upwelling and seafloor spreading that drive divergent continental drift of South America and Africa. Comparative analyses, however, show that South Atlantic opening is asymmetric and non-uniform. For neither asymmetric nor non-uniform opening are the underlying mechanisms clear. Here I use geological and geophysical data to inform analytical modelling, revealing that westward drifting and southward tapering of the South American continent have controlled the asymmetry and the non-uniformity in South Atlantic opening. I interpret that the asymmetric non-uniform seafloor spreading caused the ridge and hotspots to migrate, leaving behind non-linear seamount trails that are indicative of the speed of hotspot migration rather than direction of plate movement. The findings point towards a chain reaction from continental drifting, through seafloor spreading to ridge-hotspot interaction, which is instrumental in understanding the geodynamics for global plate tectonics.