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April 22, 2026Geochemistry Geophysics Geosystems0 citationsOpen Access

Volcanic History of Rodrigues Island and Its Relationship With the Central Indian Ridge and the Réunion Hotspot

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JSJulien SeghiVFVincent FaminXQXavier Quidelleur

Key Points

  • This research aims to investigate the volcanic history of Rodrigues Island and its geological relationship with surrounding features.
  • Integrated field studies with zircon U‐Pb and (U‐Th)/He geo-thermochronology.
  • Analyzed groundmass K‐Ar dating, and major and trace element compositions of volcanic rocks.
  • Evaluated geological features and history through volcanic construction episodes.
  • Rodrigues Island's volcanic history extends from 4.1 to 1.1 Ma, longer than previously believed.
  • Two volcanic construction phases were identified: circular volcano formation shifting to fissural volcanism.
  • Geochemical analysis indicates an eastward migration of melting, influenced by oceanic processes.

Abstract

Abstract Many intraplate volcanic chains are explained as hotspot trails formed by plate motion over mantle plumes, yet some deviate from this model. The Rodrigues Ridge, a volcanic lineament extending eastward from the Réunion hotspot track toward the Central Indian Ridge (CIR), is one such case. To assess its origin, we integrated field studies with zircon U‐Pb and (U‐Th)/He geo‐/thermochronology, groundmass K‐Ar dating, and major and trace element analyses of volcanic rocks from Rodrigues Island. Our results reveal that Rodrigues Island experienced a prolonged subaerial volcanic history from 4.1 to 1.1 Ma, 2.7 million years longer than previously thought. This history shows two episodes of volcanic construction: (a) a circular ‐volcano construction between 4.1 and 2.5 Ma, followed by erosion, subsidence, and coral reef development and (b) fissural volcanism from 2.3 to 1.1 Ma, which shaped the island's elongated morphology. Subaerial lavas are more alkalic and enriched in incompatible elements than older submarine ridge lavas. This geochemical evolution suggests an eastward migration of partial melting degree, with oceanic accretion driving magmatism along the Rodrigues Ridge. Combined with magnetic anomalies of the oceanic lithosphere, the chronology points to at least two propagation episodes toward the CIR (≥9.9–7.9 Ma and 4.1–0.4 Ma). We conclude that the Rodrigues Ridge originated as a fracture in the oceanic lithosphere, driven by plume‐related buoyancy forces and asthenospheric flow beneath the CIR, without any direct contribution from the Réunion plume to the partial melting degree. These findings emphasize the role of lithospheric stresses and oceanic accretion in shaping off‐axis volcanic chains.

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Cite This Study

Seghi et al. (2026) studied this question.

synapsesocial.com/papers/69e8661d6e0dea528ddea94ehttps://doi.org/10.1029/2025gc012748
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