Mantle Plumes Both Tall and Short?

摘要

For 3 decades, researchers have been debating whether plumes of hot rock rise through Earth's mantle. Geologists and geochemists have inferred deep plumes from traces left at volcanic hot spots such as Iceland and Hawaii. And some seismologists have suggested that they could glimpse a plume or two in their seismic "CT scans" of the mantle. Even so, plumes have stubbornly remained an appealing if unproven concept. Now, as reported online this week by Science (www.sciencemag.org/cgi/content/ abstract/1092485), a group of seismologists offers evidence of not one or two plumes but 32. Some of them span the mantle 2900 kilometers from core to crust; others hint of a surprisingly shallow origin less than 1000 kilometers down.