What controls the magma production rate along the Walvis Ridge, South Atlantic?

• Published in: Tectonophysics Vol. 883; p. 230381
• Main Authors: Huang, Liang, Li, Chun-Feng
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 23.07.2024
• Subjects: Crustal thickness; Fracture zone; Hotspot; Lithospheric thickness; Magma production rate; Walvis Ridge; Lithospheric thickness; Crustal thickness; Walvis Ridge; Hotspot; Magma production rate; Fracture zone
• ISSN: 0040-1951; 1879-3266
• DOI: 10.1016/j.tecto.2024.230381

The Walvis Ridge is a volcanic chain with the most pronounced topographic anomaly in the South Atlantic. This study analyzes the factors influencing magma production rates along the ridge to provide insights into hotspot-lithosphere interactions. With the sub-lithospheric gravity effect excluded, we determine the crustal thickness in the South Atlantic via gravity inversion. By subtracting the age-averaged crustal thickness, we isolate the excess crustal thickness attributable to ridge magmatism and calculate the magma generation rate along the Walvis Ridge over the past 80 Ma. Our results reveal a relatively lower magma production rate in the Walvis Ridge (peaking at ∼2.5 m3/s) compared to other major hotspot tracks (e.g. Hawaii-Emperor seamount chain, Ninetyeast Ridge, or Deccan-Reunion hotspot). Furthermore, variations in magma production rate show a strong inverse correlation with lithospheric thickness (or crustal age) at the time of loading but no significant correlation with spreading rate. Extensively distributed fracture zones in the lithosphere also promote magma production during the period of ∼70–40 Ma. Together with previously identified spreading-type magmatism in the northeast Walvis Ridge, we infer that external tectonic factors, other than hotspot-related factors, play a crucial role in magma production rate across the entire Walvis Ridge. [Display omitted] •Lithospheric thickness primarily controls the magma production rates at Walvis Ridge.•No correlation between magma production rates and plate motion velocity in the whole.•Concentration of fracture zones causes high magma production rates during 40–70 Ma.•Magma production rate throughout the Walvis Ridge may be not dominated by hotspot activity.