Tectonic evolution of the Greater Maldives Ridge traced in the western Indian Ocean

In a recent study, an Indian researcher traced the tectonic evolution and nature of the Greater Maldives Ridge (GMR)—a crucial geodynamic feature of the western Indian Ocean whose origin has been at the center of much debate. scientists.

The study can help reconstruct the original break-up and dispersal of Gondwanaland that led to the current configuration of continents, continental fragments, and the formation of ocean basins in the Indian Ocean.

The Maldives Ridge is an aseismic ridge that is not associated with seismic activity. This ridge, located in the western Indian Ocean, southwest of India, is not well studied. It is essential to acquire knowledge of the structure and geodynamics of seismic ridges (because they provide valuable information for understanding the evolution of ocean basins).

The study by the Indian Institute of Geomagnetism, Mumbai, an autonomous institute of the Department of Science and Technology, Govt. of India, chalked out possible geological cross-sections along the GMR for the first time using high-resolution satellite-derived gravity data. The researchers postulated that the GMR could be underlain by oceanic crust. The results of their study may provide additional constraints to better understand the evolution of Indian Ocean plate tectonics.

Research work conducted by Dr. Priyesh Kunnummal under the guidance of Dr. SP Anand provides the crustal architecture and gravitational equilibrium state between the Earth’s crust and mantle (isostasy) of the Greater Maldive ridge segment of the greater Chagos-Laccadive ridge (CLR). Their study, based primarily on the interpretation of gravity anomalies (small differences in gravity pull caused by lateral density variations within the subsoil) with broadband seismic and refraction seismic data , provided for the first time a three-dimensional image of Moho variation along the Greater Maldives Ridge and adjacent ocean basins. The depth at the boundary between the Earth’s crust and the mantle or the Mohorovicic discontinuity (Moho) on the GMR has been systematically mapped with the finer variation of the effective elastic thickness (Te) at this location. Research related to Te variations and isostatic compensation was recently published in the journal ‘Gondwana Research’.

The IIG team found that Moho is deeper on the Maldive Ridge (MR) segment and shallower to the south in the Deep Sea Channel (DSC) region. However, the effective elastic thickness values ​​(an approximation of the resistance of the lithosphere) were lower on the MR region compared to the DSC region. The Maldive Ridge and Deep Sea Channel region may likely be oceanic in nature with the presence of under-plating materials associated with Réunion hotspot volcanism. Research suggests that Maldive Ridge may have formed in close proximity to the mid-ocean ridge (where the creation of new ocean floor occurs due to divergent movement of lithospheric plates or the spreading center). During this time, the DSC region was under a long transform fault (staggered between spreading centers, which neither create nor destroy lithosphere), which hampered melt production and gave rise to the Chagos-Maldives gap. Ridge during the Plume-ridge interaction.

Satellite-derived gravity anomalies are very useful for deciphering crustal architecture when traditional shipboard geophysical data is unavailable or scarce.

“The study provides new insights into the crustal architecture, isostatic compensation mechanism and tectonic evolution of the Greater Maldives Ridge,” said Dr Priyesh.

(With GDP entries)

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