Such micro-continents in the oceans seem to occur more frequently than previously thought. The break-up of continents is often associated with mantle plumes -- these giant bubbles of hot rock rise from the deep mantle and soften the tectonic plates from below, until the plates break apart.
This is how Eastern Gondwana broke apart about 170 million years ago. At first, one part was separated, which in turn fragmented into Madagascar, India, Australia and Antarctica, which then migrated to their present position.
Plumes currently situated underneath the islands Marion and Reunion appear to have played a role in the emergence of the Indian Ocean.
