Detection of Core-Derived Ruthenium in Hawaiian Volcanic Rocks Suggests Mantle-Core Interaction
Detection of Core-Derived Ruthenium in Hawaiian Volcanic Rocks Suggests Mantle-Core Interaction
A study published in Nature on May 21, 2024, presents evidence suggesting interaction between Earth’s core and mantle. Researchers from the University of Göttingen analyzed basaltic rocks from Hawaii, focusing on ruthenium isotopes.
Over 99.95% of Earth’s gold, along with other heavy elements like platinum, resides in the planet’s molten core. This core consists of two layers: a solid inner core of iron and nickel, and a liquid outer core. The mantle, a layer of mostly solid rock, lies between the core and the Earth’s crust.
The researchers used a new technique to analyze the ruthenium content within the Hawaiian volcanic rocks. They found a specific ruthenium isotope that is believed to be more abundant in Earth’s early building materials and is largely absent from the mantle. The presence of this isotope in the volcanic rocks suggests that the rocks originated from material derived from the core-mantle boundary.
The study indicates that substantial volumes of superheated mantle material, estimated to be several hundreds of quadrillion metric tonnes, originate at the core-mantle boundary and rise to the surface, forming oceanic islands like Hawaii. The researchers note that the process of this material rising takes between 500 million and 1 billion years.
Due to the chemical similarity between ruthenium and gold, the researchers infer that the leakage of ruthenium from the core also implies a similar, albeit minuscule, leakage of gold. The amount of core-derived material in a single rock sample is negligible. The researchers obtained approximately half a kilogram of rock, from which they extracted less than milligrams of ruthenium.
The study’s lead author, Nils Messling, a geochemist at the University of Göttingen, stated that while the process is minuscule at the scale of a single island, over geological timescales (4.5 billion years), it could significantly alter Earth’s composition. Co-author Matthias Willbold, a professor at the University of Göttingen, highlighted that the findings demonstrate the Earth’s core is not as isolated as previously thought.
While the exact mechanism driving this core-mantle interaction remains unclear, the researchers emphasize that the core and mantle have different densities, akin to oil and water, and shouldn’t mix readily. The study’s findings have been positively received by other researchers in the field, who agree that the results provide strong evidence for core-mantle interaction and the contribution of core material to mantle plumes.
The research utilized samples from the Smithsonian Institution, including some obtained from a deep-sea volcano. The samples were crushed, powdered, and melted with chemicals to extract the platinum group elements, with a focus on ruthenium isotopic analysis.
In conclusion, the study provides evidence of core-derived material in Hawaiian volcanic rocks, specifically through the detection of a particular ruthenium isotope. This suggests ongoing interaction between Earth’s core and mantle, with implications for the distribution of precious metals, including gold, on Earth’s surface. Further research is needed to fully understand the mechanisms and the extent of this interaction throughout Earth’s history.
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