An enormous gravitational anomaly, where the ocean surface is 106 meters lower than its surrounding surroundings, is located deep beneath the Indian Ocean and presents an intriguing riddle. For many years, scientists have been baffled by this phenomenon, which is called the Indian Ocean Geoid Low (IOGL). By linking the anomaly to deep-seated mantle processes that started 140 million years ago, a recent study published in Geophysical Research Letters has now offered a convincing explanation.
Using cutting-edge computer simulations, researchers reconstructed the region’s geological past and discovered a surprising cause: a vast mass of hot, low-density material rising from the Earth’s mantle. Their findings link this anomaly to the African superplume, a giant upwelling of mantle material stretching beneath the Indian Ocean. Unlike other geoid lows, typically caused by subducted tectonic plates, the IOGL’s origins have long remained a mystery. Some scientists speculated that sinking plates could be responsible, but these theories failed to fully explain the anomaly’s magnitude.
By utilizing seismic tomography and geodynamic modeling, the research team traced mantle movements over 140 million years. Their analysis suggests that as the Indian subcontinent drifted northward, subducted oceanic plates sank into the mantle, triggering mantle plumes that displaced lighter material upwards—ultimately shaping the IOGL around 20 million years ago. Six of the 19 simulations conducted successfully replicated a geoid low similar to the one observed today.
However, some experts remain skeptical. Dr. Alessandro Forte from the University of Florida suggests that the study may have overlooked the influence of a significant mantle plume linked to Réunion Island and the Deccan Traps. While the models show strong correlations, discrepancies persist in other regions.
Despite the ongoing debates, the IOGL provides a unique window into Earth’s dynamic interior, offering new insights into the forces that continue to shape our planet.
