Ancient Volcanoes Reveal Earth’s Recycled Crust


Ancient volcanoes dating back billions of years could provide new insights into how the Earth’s surface is recycled, according to scientists at the University of St Andrews.

A study, published today in Nature Communications, reveals the fate of the Earth’s ancient crust and could help solve the mystery of how the Earth’s surface and mantle are connected. The Earth’s outermost layer is made up of rigid tectonic plates which move around and collide at regions called subduction zones.

In areas of collision, crustal materials get transported into the deep mantle, and one of the grand challenges in Earth Sciences is to understand what happens to this crust and how long it resides in the mantle.

At a few volcanoes on Earth geologists can find traces of these ancient crustal materials in the erupted lava. To date most of this work has focused on oceanic islands like Hawaii or the Canaries.

However, oceanic islands are only present at the surface of the Earth for a few million years before they themselves subside and are subducted back into the mantle, and so can only provide a tiny snapshot of crustal recycling over the four billion years of Earth history.

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Image via University of St. Andrew's