Nature and Origin of Magnetic Lineations Within Valdivia Bank: Ocean Plateau Formation by Complex Seafloor Spreading
Nature and Origin of Magnetic Lineations Within Valdivia Bank: Ocean Plateau Formation by Complex Seafloor Spreading
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DOI：
10.1029/2023gl103415
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发表时间：
2023-07
影响因子：
5.2
通讯作者：
S. Thoram;W. W. Sager-W.;K. Gaastra;S. Tikoo;C. Carvallo;A. Avery;A. V. Del Gaudio;Y. Huang;K. Hoernle;T. W. Höfig;R. Bhutani;D. M. Buchs;C. Class;Y. Dai;G. Dalla Valle;S. Fielding;S. Han;D. Heaton;S. Homrighausen;Y. Kubota;C.-F. Li;W. R. Nelson;E. Petrou;K. E. Potter;S. Pujatti;J. Scholpp;J. Shervais;M. Tshiningayamwe;X. J. Wang;M. Widdowson
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文献类型：
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作者：
S. Thoram;W. W. Sager-W.;K. Gaastra;S. Tikoo;C. Carvallo;A. Avery;A. V. Del Gaudio;Y. Huang;K. Hoernle;T. W. Höfig;R. Bhutani;D. M. Buchs;C. Class;Y. Dai;G. Dalla Valle;S. Fielding;S. Han;D. Heaton;S. Homrighausen;Y. Kubota;C.-F. Li;W. R. Nelson;E. Petrou;K. E. Potter;S. Pujatti;J. Scholpp;J. Shervais;M. Tshiningayamwe;X. J. Wang;M. Widdowson
瓦尔迪维亚滩（Valdivia Bank，VB）是一个晚白垩世的海洋高原，由大西洋中脊（MAR）特里斯坦-高夫热点的火山活动形成。为了更好地了解其起源和演变，利用磁测数据生成磁异常网格，并将其反演以确定地壳磁化。磁化模型揭示了穿过高原的准线性极性区，并遵循预期的MAR古位置，这意味着在异常C34 n-C33 r形成期间，海底扩张超过1.4亿年。国际海洋发现计划391号考察队的古地磁和生物地层学数据证实了这一解释。异常C33 r被分成两个负带，可能是由于一个向西向脊的跳跃。其中一个负异常与深裂谷相吻合，表明了它们的形成时代和形成机制。这些发现意味着VB起源于板块重组过程中的海底扩张型火山活动，而不是像大型火山那样来自熔岩流的垂直堆叠。
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.