Ancient rocks show water shaped Earth 3.1 bln years ago

CANBERRA, July 8 (Xinhua) -- Geologists have found new evidence that water was already influencing Earth's interior and volcanic activity more than 3 billion years ago, based on analysis of some of the planet's oldest volcanic rocks.

The Australian-led study analyzed ancient rocks from the state of Western Australia's Pilbara Craton and found signs that water had travelled deep beneath Earth's surface before helping to generate magmas that formed volcanoes like those found in today's Pacific "Ring of Fire," according to a statement released by Adelaide University on Wednesday.

The findings, published in Nature Communications, suggest that Earth was already undergoing a form of the water-recycling processes that shape the planet today, despite conditions being dramatically different during the planet's infancy.

The research provides a rare window into Earth's distant past, said Adelaide University geochemist Eric Vandenburg, who led the study.

Today, water is recycled into Earth's interior through plate tectonics, where oceanic plates sink at subduction zones. However, scientists have long debated whether such processes operated on the hotter early Earth.

The researchers propose that instead of modern plate tectonics, an earlier mechanism called "dripduction" moved water downward: dense, water-rich crust sank into the mantle, releasing water that helped generate magma, fuel volcanic eruptions, and form rocks still studied today.

The findings indicate that Earth's interior and surface were connected far earlier than previously thought, with implications for understanding continental growth, volcanic eruptions, and the ingredients essential for life.

Because rocks this old are rare, the well-preserved Pilbara Craton offers a unique record of early Earth, letting scientists reconstruct 3.1-billion-year-old events from chemical fingerprints in the rocks, according to the study.