Beneath the Indian Ocean lies a gravitational enigma — an unlimited melancholy the place the ocean floor dips 106 meters decrease than surrounding areas. Often known as the Indian Ocean Geoid Low (IOGL), this anomaly has baffled scientists for many years. Now, a research printed in Geophysical Analysis Letters affords the clearest clarification but, linking the phenomenon to deep-seated mantle processes relationship again 140 million years.
Utilizing superior laptop simulations, researchers have reconstructed the geological previous of the area, uncovering a stunning wrongdoer: a mass of sizzling, low-density materials rising from the deep mantle. Their findings counsel that this anomaly is linked to the African superplume, an enormous upwelling of mantle materials that extends beneath the Indian Ocean.
“The existence of the Indian Ocean geoid low is likely one of the most excellent issues in Earth Sciences,” says Professor Attreyee Ghosh, an Assistant Professor on the Centre for Earth Sciences, Indian Institute of Science, Bangalore. “It’s the lowest geoid/gravity anomaly on Earth, and thus far, no consensus existed relating to its supply.”
In contrast to different geoid lows, usually linked to subducted tectonic plates, the IOGL’s origins have remained elusive. Some earlier theories speculated that sinking plates might be accountable, however none totally defined the dimensions of the anomaly.
To resolve this thriller, researchers turned to seismic tomography and geodynamic fashions, tracing mantle actions over 140 million years. Their evaluation revealed a placing correlation between the IOGL and an historic tectonic occasion: the gradual disappearance of an ocean because the Indian subcontinent drifted northward.
“The Earth is mainly a lumpy potato,” Ghosh explains. “Technically, it’s not a sphere, however what we name an ellipsoid, as a result of because the planet rotates, the center half bulges outward.” This irregular form, mixed with mantle convection, helps clarify why gravity behaves in a different way throughout varied areas.
As India’s landmass moved, subducted oceanic plates sank into the mantle, triggering mantle plumes that pushed lighter materials upward — altering gravity within the course of. This course of seemingly led to the formation of the IOGL round 20 million years in the past.
To check their concept, the group ran 19 completely different simulations, recreating plate shifts and mantle dynamics over thousands and thousands of years. In six of those fashions, a geoid low resembling the one within the Indian Ocean emerged with the presence of mantle plumes taking part in a key function.
Not all consultants are satisfied. Dr. Alessandro Forte, a geologist on the College of Florida, informed Day by day Galaxy that the research could overlook the function of an enormous mantle plume answerable for the volcanic eruptions of Réunion Island and the Deccan Traps. Furthermore, whereas the fashions present an 80% correlation between predicted and noticed geoids, discrepancies persist in different areas just like the Pacific, Africa, and Eurasia.
For now, the IOGL stays a window into Earth’s shifting inside — one that will maintain extra secrets and techniques concerning the forces shaping our planet.
