Thoram, S.Sager, W. W.Gaastra, K.Tikoo, S. M.Carvallo, C.Avery, A.Del Gaudio, Arianna V.Huang, Y.Hoernle, K.Höfig, T. W.Bhutani, R.Buchs, D. M.Class, C.Dai, Y.Valle, G. DallaFielding, S.Han, S.Heaton, D. E.Homrighausen, S.Kubota, Y.Li, C. F.Nelson, W. R.Petrou, E.Potter, K. E.Pujatti, S.Scholpp, J.Shervais, J. W.Tshiningayamwe, M.Wang, X. J.Widdowson, M.2025-05-312025-05-310094-8276ORCID:/0000-0001-7727-4315/work/175320583http://www.scopus.com/inward/record.url?scp=85165447479&partnerID=8YFLogxKhttps://hdl.handle.net/1885/733755945Valdivia Bank (VB) is a Late Cretaceous oceanic plateau formed by volcanism from the Tristan-Gough hotspot at the Mid-Atlantic Ridge (MAR). To better understand its origin and evolution, magnetic data were used to generate a magnetic anomaly grid, which was inverted to determine crustal magnetization. The magnetization model reveals quasi-linear polarity zones crossing the plateau and following expected MAR paleo-locations, implying formation by seafloor spreading over ∼4 Myr during the formation of anomalies C34n-C33r. Paleomagnetism and biostratigraphy data from International Ocean Discovery Program Expedition 391 confirm the magnetic interpretation. Anomaly C33r is split into two negative bands, likely by a westward ridge jump. One of these negative anomalies coincides with deep rift valleys, indicating their age and mechanism of formation. These findings imply that VB originated by seafloor spreading-type volcanism during a plate reorganization, not from a vertical stack of lava flows as expected for a large volcano.We thank the captains and crews of R/V (TN‐373, TN‐374) and D/V (IODP Expedition 391) for their assistance in collecting data. We especially appreciate the hard work and efficiency of the IODP technical staff. ST and WS were supported by NSF Grant OCE‐1832197, which also supported cruises TN‐373 and TN‐374. ST, WS, KG, SMT, and AA were supported by the US Science Support Program for Expedition 391 research. CC and AVD were supported by ECORD. YH was supported by National Natural Science Foundation of China Grant 42006056. We thank Doug Wilson and an anonymous reviewer for constructive comments that significantly improved this paper. Thomas G. Thompson JOIDES resolution11enPublisher Copyright: © 2023. The Authors.hotspot-ridge interactionInternational Ocean Discovery Program (IODP) Expedition 391magnetic anomaliesoceanic plateauValdivia BankWalvis Ridge2023-07-1610.1029/2023GL10341585165447479