AsianScientist (Apr. 11, 2011) – New research from The Australian National University and collaborators has accurately recorded for the first time what was once considered purely theoretical – yo-yo subduction.
The research, which was published online today in the journal Nature Geoscience, was carried out by Dr. Daniela Rubatto and co-workers from the ANU Research School of Earth Sciences, along with collaborators at the University of Bern and University of Torino.
Understanding subduction zones is critical as they are the areas where plates meet and merge, where volcanos form, where lava is generated and where earthquakes happen, said Rubatto. This discovery may also change the way we look at plate collision zones and mountain building.
Conventional view suggests that subduction zones – where the Earth’s crust is pushed down through the convergence of tectonic plates – happens only once.
Rubatto and colleagues found that this was not the case. They determined that within a subduction zone, the Earth’s crust is pushed down from the planet’s surface to a depth of 60 to 100 km, comes back towards the Earth’s surface, is pushed down again and then finally ends up back on the surface where it becomes part of mountain belts.
This process resembles the movement of a yo-yo, hence its name, yo-yo subduction.
“On top of this we can prove that all this happens in a relatively short geological time of less than 20 million years. To put this time into context a mountain belt normally takes 50-100 million years to form and the rocks around Canberra have been moving up or down only a few kilometers in the last 400 million years,” said Rubatto.
The breakthrough was made by looking at rocks from the Italian Western Alps. Rubatto said it came about through selecting the right sample of rock, the ability to make accurate chemical measurements of tiny minerals with the ANU-built SHRIMP ion microprobe and some luck.
“Our new methodology of investigating rocks is like being finally able to read a flight recorder. So far we have known where the plane started, that it had a stop over, and finally landed at its destination. Now we can read the actual route of the plane, how fast it went, and how long it took – and find out that it went to a destination twice,” she said.
———
Source: Australian National University.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.
