Hotspot volcanism, mantle plumes, and island chain formation
Mantle plumes are columns of anomalously hot rock that rise from deep in the mantle (possibly the core-mantle boundary) and create hotspot volcanism independent of plate boundaries. As the tectonic plate moves over a stationary plume, a linear chain of volcanic islands forms — older and more eroded islands trailing in the direction of plate motion. The Hawaiian-Emperor seamount chain records 80 million years of Pacific Plate motion; a 43° bend in the chain around 47 Ma records a dramatic change in plate direction. Plumes are detected seismically as low-velocity anomalies and generate large igneous provinces (LIPs) when they first arrive, sometimes triggering mass extinctions.