We are excited to invite you to the next seminar of the 2025 Geology and Geophysics Seminar Series, featuring Caesar Rigoti, who is a PhD candidate in the School of Geosciences, University of Sydney. Caesar will be presenting on “Plate-plume interaction driving microcontinent formation in the South Atlantic: Evidence from the Rio Grande Rise and Valdivia Bank“. In this engaging talk, he will discuss how mantle plume and plate interactions shaped the Rio Grande Rise–Valdivia Bank system, revealing evidence for a microcontinental origin and offering new insights into continental breakup and plume dynamics.
Date: November 12, 2025
Time: 11:00 a.m. – 12:00 p.m., Sydney Time
Location: Room 335 (Conference Room), Madsen Building (F09), School of Geosciences
or Online (Join via zoom)
We look forward to seeing you there in person or joining us online!
https://uni-sydney.zoom.us/j/88099799836?from=addon
Plate-plume interaction driving microcontinent formation in the South Atlantic: Evidence from the Rio Grande Rise and Valdivia Bank
Abstract
The Rio Grande Rise is a prominent bathymetric feature in the South Atlantic Ocean. While its formation was influenced by the Tristan–Gough mantle plume and the mid-ocean ridge, the roles of rifting, continental breakup, and its connection to the Valdivia Bank remain controversial. This study integrates geological, geochemical, and geophysical data with a new plate reconstruction to evaluate if these features include microcontinental fragments and how they formed. We present a new kinematic plate reconstruction illustrating the Rio Grande Rise-Valdivia Bank system’s breakup from Gondwanan margins around 100 Ma (Early Cretaceous), evolving through microplate formation and culminating in final separation by 72 Ma (Campanian). Our synthesis of evidence demonstrates that the Rio Grande Rise is a microcontinent, challenging purely oceanic plateau interpretations and supporting a hybrid origin involving plume-plate interaction during a distinct microplate stage. This refined model highlights the influence of inherited tectonic structures and plume dynamics in shaping continental fragmentation, offering new insights into microcontinent formation within plume-influenced rifted margins and providing a framework for interpreting similar systems globally.
Graphical Abstract
