Trickle-down geodynamics

摘要

In a paper on page 620 of this issue, Maier et al. provide a provocative hypothesis for those engaged in the study of Earth's evolution. Their evidence comes from measurements of the concentrations of platinum-group elements (PGE) in ancient volcanic rocks known as komatiites, which originated from deep within the mantle.rnMaier et al. find that the contents of these elements in 3.5-billion- to 3.2-billion-year-old komatiites from Barberton in South Africa and Pilbara in Western Australia are lower than those in younger komatiites.