Ancient rocks reveal early Earth's water-driven volcanism before plate tectonics
Analysis of 3.13–3.10 billion-year-old pillow lavas from the Pilbara Craton in Western Australia shows a boninite-dominated magma suite requiring substantial water in the mantle. The team estimates the mantle source contained about 0.8–1.5% water by weight, consistent with arc-like volcanism today, suggesting surface water was recycled deep into the mantle via a dripping, non-plate-boundary process called dripduction. While based on a single volcanic package and with alternative explanations possible, the findings imply early Earth had active water cycling and arc-style volcanism long before modern plate tectonics formed.