Scientists at the University of Liverpool have found evidence of an ancient micro-continent buried beneath the Indian Ocean which formed in the last 16 millions years. This ancient precambrian continent, named Mauritia, extends more than 1500 km in length from the Seychelles to the island of Mauritius and contains rocks as old as 2,000 million years. According to Professor Nick Kusznir, who led the University of Liverpool's processing and analysis of satellite gravitational field anomalies to map the Indian Ocean crustal thickness, there are remnants of fragmented continents under the Indian Ocean.
The research team believe that this micro-continent was split off from Madagascar and India between 61 and 83 million years ago as one single land mass rifted apart to form the continents around the today's Indian Ocean. Much of it was then smothered by thick lava deposits as a result of volcanic activity and submerged beneath the waves. There are five or six other micro-continent fragments under the Indian Ocean and there are more similar features in the Atlantic and Arctic Oceans.
Scientists from the University of Liverpool's School of Environmental Sciences used satellite derived data to map crustal thickness under the Indian Ocean. Using geophysical data processing techniques the team were able to identify areas where the crust beneath the sea-floor was up to 30km or more thick, the same thickness as continental crust but much greater than that of oceanic crust which is on average only about 7 km thick. The crustal thickness mapping techniques using satellite data developed by Liverpool and industry partners are applied to deep-water oil and gas exploration in frontier areas and have also been used for governments making UNCLOS law of sea territorial claims.
Collaborating researchers from Oslo University analysed sand grains from beaches in Mauritius, a volcanic island about 900 kilometres east of Madagascar. They found the sand contained tiny crystals of ancient zircon, a mineral normally associated with a continental crust and dated between 660 million and two billion years old, a lot older than the sand grains which were formed from the nine million-year-volcanic activity on Mauritius, part of the Southern Mascarene Plateau.
The Laccadive–Chagos Ridge and Southern Mascarene Plateau in the north-central and western Indian Ocean, respectively, are thought to be volcanic chains formed above the Réunion mantle plume over the past 65.5 million years.
The research is published in Nature Geoscience.
Source: University of Liverpool
Featured image: A map of crustal thickness for the Indian Ocean derived from satellite derived gravity anomaly data (Map produced with permission of Bradley Geoscience)
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