Deep-earth history hidden within African diamonds
Islamabad-Diamonds are sometimes described as messengers from the deep earth; scientists study them closely for insights into the otherwise inaccessible depths from which they come. But the messages are often hard to read.
Now, a team has come up with a way to solve two longstanding puzzles: the ages of individual fluid-bearing diamonds, and the chemistry of their parent material. The research has allowed them to sketch out geologic events going back more than a billion years — a potential breakthrough not only in the study of diamonds, but of planetary evolution. Gem-quality diamonds are nearly pure lattices of carbon. This elemental purity gives them their luster; but it also means they carry very little information about their ages and origins.
However, some lower-grade specimens harbor imperfections in the form of tiny pockets of liquid — remnants of the more complex fluids from which the crystals evolved.
By analyzing these fluids, the scientists in the new study worked out the times when different diamonds formed, and the shifting chemical conditions around them. “It opens a window — well, let’s say, even a door — to some of the really big questions” about the evolution of the deep earth and the continents, said lead author Yaakov Weiss, an adjunct scientist at Columbia University’s Lamont-Doherty Earth Observatory, where the analyses were done, and senior lecturer at the Hebrew University of Jerusalem. “This is the first time we can get reliable ages for these fluids.” The study was published recently in the journal Nature Communications.