Earth’s longest preserved linear volcanic ridge generated by a moving Kerguelen hotspot

Abstract

Recent seismic tomography unveiled complex mantle plume structures diverging from the originally proposed single, narrow, and vertically-oriented plume conduits, which necessitates new perspectives on the mechanism of hotspot motion. While several recent endeavours have focused on Pacific hotspots’ motion, knowledge of others remains limited. Here we constrain the motions of the Kerguelen hotspot within the Indian Ocean by obtaining robust ⁴⁰Ar/³⁹Ar ages for the Ninetyeast Ridge, Earth’s longest linear volcanic ridge. These data indicate varying volcanic progression rates along the ridge, contrasting to a constant rate as previously documented. Combined with constraints on the Indian Plate motion and seafloor spreading, we reveal four periods of motions of the hotspot caused by its interactions with the Indian–Antarctic spreading ridge. This suggests that mantle plume lateral flows are susceptible to changes in shallow mantle convection due to the existence of horizontal ponding zones and vertical conduits, especially in the shallow asthenosphere.

The Ninetyeast Ridge is the world’s longest linear volcanic feature. 40Ar/39Ar ages show that the > 5000 km-long ridge was generated by a moving hotspot and reveal the hotspot’s interaction with a spreading ridge during the opening of the Indian Ocean.