Javier Cámara-Rica 🐝🇪🇸

Can Iceland be part of a previously unknown continent?

A team of geologists believes that it is not an island, but a fragment of the ancient crust of Pangea.

The idea, of course, is novel, although for now it is only a possibility: Iceland may not be an island, but the visible part of a hitherto unknown continent, most of which lies beneath the waters of the Atlantic Ocean.

"There is a hidden continent just under the sea," says Gillian Foulger of Durham University, who has just presented, together with some of her colleagues, her theory in a book published by the Geological Society of America.

Iceland is known to be part of the Mid-Atlantic Ridge, where two of the Earth's tectonic plates are slowly moving apart. Hot magma from the interior of the planet gushes along this huge submarine ridge and, as it cools, creates new crust, which pushes the old crust towards the continental coasts, where it sinks back into the mantle. This is why the crust is thinner on the seabed than on the continents, but the researcher believes that Iceland is an anomaly.

Geologists are well aware that Iceland is made of oceanic crust accumulated over millions of years, but they still cannot explain how it could have become so thick just at that point. In general, Foulger stresses, on the ocean floor "the crust is normally between 6 and 7 km thick, but under Iceland it is as much as 40 km."

Until now, geologists have argued that the unusual thickness of the oceanic crust in Iceland could be explained by the presence of a "hot spot," an unusually hot region of the mantle that leads to increased volcanic activity. But Foulger disagrees and proposes an alternative explanation: that Iceland is actually made of continental, not oceanic, crust, as is a large area of the surrounding seafloor. Which, according to the researcher, would explain all its strange features. In this way, she says, "it all fits - why didn't we see it before?"

A fragment of Pangea
If it really exists, which will have to be determined by further studies, the hidden continent would have an area of 600,000 square km, although it is possible, say the researchers, that it also includes a second region that lies northwest of Scotland, which would give a total area of more than one million square km.

The continent, for which Foulger and his team have retained the name Iceland, would be a relic of a distant time, when the continents now separated by the Atlantic were united in a single supercontinent, Pangaea. Later, due to the movement of tectonic plates, the continents separated. Foulger believes that her proposed new continent is actually an unusually hard fragment of Pangaea that has been "stretching" further and further, but not breaking apart, and now lies just below Iceland.

Which, according to Foulger, implies that Pangaea has not yet broken apart completely. Now, his team is about to collect a very resistant type of crystals there, the Iceland zircons, whose analysis could confirm whether we are really looking at a piece of the old continental crust of Pangaea.

The way to find out is relatively simple. Continental crust, in fact, is usually several billion years old, while oceanic crust, which is continually being created and destroyed, is no older than a few hundred million years. If the zircons collected by Foulger's team exceed that age, her idea would be supported by important evidence.

For the researcher, moreover, the Icelandic case may not be unique: "something similar could be happening in many more places". For example, recently a team of geologists managed to demonstrate that the islands of New Zealand are, in fact, the protruding part of a much larger continent, Zealandia.

Artículo de @José Manuel Nieves en ABC: 

¿Puede Islandia formar parte de un continente desconocido hasta ahora?

Un equipo de geólogos cree que no se trata de una isla, sino de un fragmento de la antigua corteza de Pangea

https://www.abc.es/ciencia/abci-puede-islandia-formar-parte-continente-desconocido-hasta-ahora-202107060213_noticia.html