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Nature and origin of magnetic lineations within Valdivia Bank: Ocean plateau formation by complex seafloor spreading

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. ORCID:, Class, C., Dai, Y., Valle, G. Dalla, Fielding, 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. and Widdowson, M. 2023. Nature and origin of magnetic lineations within Valdivia Bank: Ocean plateau formation by complex seafloor spreading. Geophysical Research Letters 50 (13) , e2023GL103415. 10.1029/2023GL103415

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Valdivia 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.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Earth and Environmental Sciences
Publisher: Wiley Open Access
ISSN: 0094-8276
Date of First Compliant Deposit: 31 July 2023
Date of Acceptance: 11 May 2023
Last Modified: 02 Aug 2023 16:52

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