第九届青年地学论坛

Many oceanic plateaus formed at or close to spreading ridges. Consequently, their formation, a topic of ongoing research, was attributed to hotspot-ridge interaction. However, the lack of data coverage over these plateaus creates uncertainty when it comes to defining the influence exerted by the ridges. Inspecting magnetic anomaly patterns and geomorphological characteristics of these features can provide insights into their evolution. Our research focuses on the genesis and evolution of Ceara Rise, located to the west of the Equatorial Mid-Atlantic Ridge (MAR). we combined our newly generated magnetic anomaly map and its interpretation with previous reconstructions of the equatorial Atlantic and the compilation of bathymetric, gravitational, geochemical, and seismic data of the region, including Ceara Rise’s conjugate feature Sierra Leone Rise (SLH). Our magnetic anomaly map over Ceara Rise allowed the identification of linear and curvilinear magnetic anomalies at its center. The preserved anomaly trends within Ceara Rise, along with its link to the SLH through the Equatorial’s reconstruction, imply its formation by ridge-hotspot interaction during Late Cretaceous before anomaly C34n (~83.6). However, those magnetic anomalies, during and up to 20Ma after the time of the edifice’s formation, are poorly defined. Our interpretation of the map and the presence of curvilinear patterns and discontinuities amongst the identified magnetic anomalies linked the contributions of complex mechanisms and factors, such as ridge propagation, hotspots, and potentially a meteorite impact ~ 66 Ma. This study further emphasizes the need for a nuanced understanding of oceanic plateaus and their formation mechanisms, considering their significant role for comprehending the intricate Late Cretaceous tectonic evolution in the Equatorial Atlantic.

洋底高原,洋中脊-地幔柱,海洋磁法