Flow in the Earth’s mantle drove movement of part of the Pacific tectonic plate over 120 million years ago, reports a study published online this week in Nature Geoscience. Previously it was unclear whether tectonic plates that formed at mid-ocean ridges were dragged along by flow in the underlying mantle, or whether movement of the overlying plate induced flow in the mantle.
Shuichi Kodaira and colleagues used seismic data to image a part of the Pacific Plate that formed at an ancient mid-ocean ridge in the Pacific Ocean over 120 million years ago. They identified dipping structures within the plate that suggest that the mantle moved at a much faster rate than the plate. The researchers suggest that mantle flow actively dragged the overlying plate away from the mid-ocean ridge.