Approximately 3,000 kilometres deep beneath the Earth’s crust is a hot, dynamic core that was long assumed to be geochemically isolated from the remainder of the planet. However, a breakthrough new research paper has discovered compelling evidence that the Earth’s core is far from as isolated as previously believed. Rather, it seems to be gradually “bleeding” valuable metals, such as gold, into the upper regions of the planet.
Earth unearths precious metals hidden deep within its core
The study, led by researchers from the University of Göttingen in Germany, employed volcanic rocks collected in Hawaii, a chain of volcanic islands created by mantle plumes stretching deep into the Earth. With state-of-the-art isotopic analysis methods, the researchers found abnormally high concentrations of the isotope ruthenium-100 (^100Ru) in the rocks. This isotope is found to be vastly more concentrated in the Earth’s core than in either the mantle or crust. Its occurrence in surficial volcanic rocks indicates the material had moved from the core-mantle boundary, ascending in plumes of superheated material from the mantle.“When we first looked at the first results, we knew that we had hit gold in the literal sense,” said Dr. Nils Messling, lead geochemist on the study. “We had proven what we had hoped with our data: rock from the core, such as gold and precious metals, is migrating into the mantle and being carried to the surface.”
Earth’s core metals are leaking into the mantle and crust
The center of the Earth, built up over 4.5 billion years, holds most of the Earth’s precious metals. Indeed, more than 99.999% of the Earth’s gold is thought to be locked in the core, along with platinum, iridium, and ruthenium, other siderophile (iron-loving) elements. The metals were out of geochemists’ reach for decades, behind a rock barrier hundreds of kilometres wide.The new observations contradict that assumption. The occurrence of ^100Ru in rocks in the overlying rocks is definite geochemical proof that material is leaking out of the core and becoming recycled back into the crust and the mantle. Motivation for the process seems to be mantle plumes—columns of rock superheated by contact with the core-mantle boundary and thrust into the Earth’s lithosphere to create volcanic islands such as Hawaii.
Earth’s core and mantle are more interconnected than previously thought
Study co-author Professor Matthias Willbold pointed out the wider significance of the findings. “Our data not only show that Earth’s core is less geochemically isolated than before,” he said. “We can now also demonstrate that enormous amounts of superheated mantle material—the hundreds of quadrillions of metric tons—take their origin at the core-mantle boundary and make it to the surface.This revelation has profound consequences for our understanding of Earth’s internal structure and dynamics. It suggests that the core and mantle are more interconnected than previously believed, allowing for the exchange of materials across boundaries that were once considered impermeable. While the possibility of drawing gold out of the Earth’s core is still well outside our technological reach, the find does inform us further about the surface distribution of the precious metals. If core rocks truly are contributing to it from the mantle plumes, it might be a contributing factor in some of the anomalies in the availability of gold and other rare metals in some areas—particularly volcanic island arcs. With this acknowledgment, it will ultimately play a role in prospecting for precious metal deposits, by targeted exploration of geologically active regions linked with deep mantle processes.Also Read | NASA’s Perseverance rover captures dust devil in stunning Martian selfie celebrating 1,500 sols of exploration