An international team of geoscientists has discovered a lost continent buried under the Indian Ocean. Their findings suggest that the popular tourist destinations of Reunion and Mauritius are hiding a micro-continent that’s been covered by volcanic rocks for millions of years.
A fragment of the lost continent, known as Mauritia, disconnected and disappeared approximately 60 million years ago while Madagascar and India drifted apart. The study’s findings, which were published in the journal Nature Geosciences, suggest that such micro-continents occur more frequently than previously thought.
The scientists note that the break-up of continents is often linked to mantle plumes. A mantle plume is an upwelling of abnormally hot rock within the Earth’s mantle. Scientists believe that mantle plumes soften the tectonic plates from below, until the plates split apart at the hotspots. They contend that major mantle plumes were responsible for the break-up of Eastern Gondwana approximately 170 million years ago. At first, one part was separated, which eventually fragmented into Madagascar, India, Australia and Antarctica.
The scientists believe that mantle plumes currently located underneath the islands Marion and Reunion likely played a major role in the emergence of the Indian Ocean. Furthermore, if the zone of the rupture is situated at the edge of a land mass, fragments of this land mass may be split off.
The international team of geoscientists concluded, based on the study of lava sand grains from the beach of Mauritius, that further fragments may exist under the Indian Ocean. They discovered that the sand grains hold semi-precious zircons aged between 660 and 1970 million years.
“We propose that the zircons were assimilated from ancient fragments of continental lithosphere beneath Mauritius, and were brought to the surface by plume-related lavas,” write the study’s authors in a letter describing their findings.
The scientists also conducted a recalculation of plate tectonics to confirm their findings. The recalculation reveals how and where the fragments ended up in the Indian Ocean.
“On the one hand, it shows the position of the plates relative to the two hotspots at the time of the rupture, which points towards a causal relation,” says Dr. Bernhard Steinberger of the GFZ German Research Centre for Geosciences. “On the other hand, we were able to show that the continent fragments continued to wander almost exactly over the Reunion plume, which explains how they were covered by volcanic rock.”
Based on the fact that the continental fragments were previously not recognized as such because they were hidden by the volcanic rocks of the Reunion plume, scientists have concluded that such micro-continents in the ocean occur more frequently than previously thought.
“We suggest that the plume-related magmatic deposits have since covered Mauritia and potentially other continental fragments,” add the authors.
Photo credit: GFZ/Steinberger