Publication Date:
2024-02-07
Description:
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.
Key Points
- Valdivia Bank is characterized by quasi-linear magnetic anomalies that are parallel to the inferred paleo-Mid-Atlantic Ridge
- Magnetic anomalies imply that the plateau becomes younger E-W consistent with formation via seafloor spreading during anomalies C34n-C33r
- Rift valleys, division of C33r, and anomaly curvature imply complex ridge tectonics and a ridge jump
Type:
Article
,
PeerReviewed
Format:
text
Format:
text
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