As far as we know, Earth is the only planet that still has active plate tectonics. That’s hugely significant – after all, the movement of these plates is responsible for everything, from our atmosphere to our volcanoes, from our mountains to our oceans.
A new collaboration between Canadian and Turkish researchers has highlighted that, despite their omnipresence, there’s so much about tectonics that we still don’t know. Writing in Nature Communications, they announced that they have fresh evidence for “drip tectonics”, a relatively new type of planet-carving process.
The team from the University of Toronto (UT) and Istanbul Technical University (ITU) were looking at a volcanic range in Central Anatolia. Volcanoes form through a wide range of processes, and take many different forms across a variety of environments.
These volcanoes, however, are unusually high, as was a nearby mountain range. The entire plateau, in fact, had apparently risen by about a kilometer (0.62 miles) over the past 10 million years.
There are no conventional plate tectonic boundaries in the region, which means that normal mountain-building or volcano-forming tectonic processes weren't responsible. The team reasoned that something weird must be happening beneath the surface, so they whipped out some cutting-edge computational models and gave them a whirl.
Seismological imaging discovered that the crust and the upper mantle – collectively known as the lithosphere – beneath the plateau had all but completely disappeared. Considering that the only way to go is down, something unusual must have caused it to collapse into the hellish depths of the lower mantle, but what?
Models suggest that long ago, the plateau began to fold due to regional compression. This caused the lithosphere to get squashed up, which meant that it became overly thick.
The lower segment of the lithosphere was forced down into the lower mantle, where its own weight caused it to “drip” off and eventually fall into the hellish depths. This left a huge gap beneath Central Anatolia, which the lower mantle rushed up to fill over several million years.
Ultimately, the plateau sprang up, like a snapped elastic band.
“By dropping this dense lithospheric anchor, there has been an upward bobbing of the entire land mass across hundreds of kilometers,” lead author Oğuz H. Gӧğüş, associate professor of geodynamics at ITU, said in a statement.
The authors pay a poignant tribute to John Tuzo-Wilson, the UT geophysicist who pioneered the theory of plate tectonics back in the 1960s.
“I am pleased that we are continuing his legacy in geophysics with our work,” co-author Russell Pysklywec, chair of the department of Earth sciences at UT, said.
“One thing that is certain, however, is that Earth is always active and we are just beginning to understand how it works.”