학술논문
Nature and Origin of Magnetic Lineations Within Valdivia Bank : Ocean Plateau Formation by Complex Seafloor Spreading
Document Type
Author
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. 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.; Widdowson, M.
Source
Geophysical Research Letters. 50(13)
Subject
Language
English
ISSN
0094-8276
Abstract
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.