Ignition of the southern Atlantic seafloor spreading machine without hot-mantle booster

• Published in: Scientific reports Vol. 13; no. 1; p. 1195
• Main Authors: Sauter, Daniel, Manatschal, Gianreto, Kusznir, Nick, Masquelet, Charles, Werner, Philippe, Ulrich, Marc, Bellingham, Paul, Franke, Dieter, Autin, Julia
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 21.01.2023; Nature Publishing Group; Nature Portfolio
• Subjects: 704/2151/210; 704/2151/562; Continental crust; Cretaceous; Hot spots (geology); Humanities and Social Sciences; Isotopes; Lava; Magma; multidisciplinary; Ocean floor; Oceanic crust; Science; Science (multidisciplinary); Sciences of the Universe; Seafloor spreading; Spreading
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-023-28364-y

The source of massive magma production at volcanic rifted margins remains strongly disputed since the first observations of thick lava piles in the 1980s. However, volumes of extruded and intruded melt products within rifted continental crust are still not accurately resolved using geophysical methods. Here we investigate the magma budget alongside the South Atlantic margins, at the onset of seafloor spreading, using high-quality seismic reflection profiles to accurately estimate the oceanic crustal thickness. We show that, along ~ 75% of the length of the Early-Cretaceous initial spreading centre, the crustal thickness is similar to regular oceanic thickness with an age > 100 Ma away from hot spots. Thus, most of the southernmost Atlantic Ocean opened without anomalously hot mantle, high magma supply being restricted to the Walvis Ridge area. We suggest that alternative explanations other than a hotter mantle should be favoured to explain the thick magmatic layer of seaward dipping reflectors landward of the initial mid-oceanic ridge.