Paleogeographic significance of unknown hyperextended continental crust in South Atlantic conjugated margin

Abstract

The paleogeographic reconstruction of fragmented and dispersed continents often poses a challenge due to the lack of information regarding the nature of that extend beneath passive margin basins. To define the width of the continental crust beneath passive margin basins and its implications for paleogeographic reconstruction of conjugate continental margins, this study investigates the architecture of the stretched continental crust of the southern South Atlantic conjugate margin. The investigated region encompasses South Africa, Namibia, southern Brazil, and Uruguay, which were formed during the Mesozoic rifting of SW Gondwana. Employing a multi-tool approach combining seismic interpretation, gravity, magnetometry, and U-Pb isotopic data, the research aims to quantify the extension of stretched continental crust and its implications for plate reconstructions. The study reveals that the restored stretched crust spans at least 150 km, emphasizing the significance of considering connections between both margins for realistic paleogeographic reconstructions. Furthermore, the distinct U-Pb zircon age distribution patterns between SW Africa and SE South America reinforce the lack of direct connections despite their Gondwanan origin. The missing link estimated in this study is around 150 km, comparable in size to major mountain ranges such as the Andean or Urals. This work sheds light on critical aspects of Earth’s dynamic crustal evolution and emphasizes the need for comprehensive reconstructions considering stretched and eroded crust in the South Atlantic conjugate margin.