If you thought discovering the 7 continents was a thing of centuries past, you'll be surprised to hear we misplaced an entire continent under the island of Mauritius. New data from crystals on the island present proof that there is in fact an ancient continent sitting beneath the island. This, coming from an island located 1,200 miles off the southeast coast of Africa.
The ancient continent, known as Mauritia, once connected Madagascar to India during the Gondwana supercontinent. As India began its voyage north, some 120 million years ago, to eventually smash into Europe, it was split apart from Madagascar and the remnants of Mauritia fell into the Indian Ocean.
However, until recently, scientists had not known about the now missing continent that disappeared as a result of the breaking apart of Gondwana. A few clever geologists were able to measure crystals called zircons that had been expelled from volcanic eruptions on Mauritius. After measuring the crystal's age, they gave a puzzling answer of billions of years old. This, compared to the much younger age of the island led researchers down a path of investigation which ultimately led to the recent publication in Nature Communications.
To back up a bit, geologists had noted a strange anomaly in Earth's gravitational pull over the island of Mauritius. Gravity does vary depending on where you are on Earth, albeit nominally, due to changes in the underlying mass associated with Earth's gravitational force. For instance, variations in Earth's crustal thickness and density due to different rock types will affect the gravitational pull in that location. The unusually high gravity measurements over Mauritius suggested there was a deep continental mass below the island that had previously been uncharacterized.
Mauritius sits on top of what geologists and astrophysicists call a mascon, or a region whereby a positive gravitational anomaly is associated with a depressed high density mass below the surface of the Earth. The evidence for a deep missing continent mounted as 13 zircon grains were found within an in-place lava outcrop on Mauritius, affirming the crystals were not brought in by some other means. These zircons were uranium-lead age dated to be between 2.5- and 3-billion-years-old. Contrast that with the 8-million-year-old Mauritius island and it's clear the zircons came from a much older deeper continental body.
The zircons were transported to the surface through volcanic eruptions bringing ancient rocks to the surface of Mauritius. Zircons are an ordinary gemstone found in granites from continental crust and are an incredibly accurate way to measure ages on the order of hundreds of millions to billions of years old.
The timeline looks something like this: The breakup of Gondwana began roughly 200-million-years-ago, with India splitting apart 120-million-years-ago. As India broke away from Madagascar and the larger Gondwana supercontinent, the landmass connecting the two fractured and sank into the newly formed ocean crust. The continent continued to sink, compress, and become heated until it was launched to the surface by the volcanoes that created the Mauritius island.
This may not be the last lost continent geologists will find as they continue to search for inconsistencies in rock ages and gravity anomalies around the world.
Read More: New Zealand Is Not Just A Small Bunch Of Islands - It's The Lost Continent Of Zealandia
