An extraordinary find in 62-million-year-old Arctic rocks, where record-breaking concentrations of a helium isotope were detected, may offer compelling evidence of a long-standing mystery – a gradual escape of Earth’s core.
Earth’s core, an area of immense heat and pressure, remains largely inaccessible to direct exploration. To unravel its mysteries, scientists have had to rely on indirect clues, such as the behavior of seismic waves. However, an intriguing revelation in ancient Arctic rocks suggests a novel avenue for understanding the inner workings of our planet.
Helium, a notoriously elusive element due to its lightweight and non-reactive nature, is rare on the Earth’s surface. The challenge lies in determining how much helium remains concealed within Earth’s depths, a critical enigma in geology.
The prevailing belief is that, over billions of years, Earth should have released most of the helium it trapped during its formative years. Therefore, any helium found in relatively recent volcanic rocks must have originated from deeper reservoirs yet to expel their helium or from a gradual, ongoing leakage.
Researchers from the Woods Hole Oceanographic Institution and the California Institute of Technology have been investigating this phenomenon. Their previous analysis of ancient lava flows, particularly in basaltic lavas on Canada’s Baffin Island, uncovered an unusually high ratio of helium-3 (3He) to helium-4 (4He). This ratio, significantly exceeding atmospheric levels, suggests that the helium’s source is ancient and not due to contamination by the atmosphere.
Recent investigations have expanded on this discovery. By analyzing olivine samples from various sites across Baffin and its neighboring islands, the researchers achieved a helium-3 to helium-4 ratio nearly 70 times greater than atmospheric levels. This is the highest ratio recorded in volcanic rock, further cementing the helium’s unique origin hypothesis.
To strengthen their case, the research team considered ratios of other isotopes, including strontium and neodymium, ruling out post-eruption alterations to the helium’s identity. In addition, the measurement of neon isotopes in these rocks paralleled conditions during Earth’s formation, indicating an ancient vault of secrets hidden beneath our planet’s surface.
Simulations of Earth’s inner dynamics, encompassing thermodynamics, pressures, and composition, propose that noble gases like helium and neon might have been sequestered in the core as Earth evolved. Over eons, these gases gradually migrated into the surrounding mantle. This revelation holds the potential to transform our understanding of how Earth’s core influences geological processes and planetary formation.
While Earth’s core remains an enigmatic and inaccessible realm, this newfound evidence hints at a remarkable avenue for future research. If Earth’s core does indeed “leak” noble gases like helium, it could serve as a unique window into the inner workings of our planet and offer insights into the formation of celestial bodies from primordial matter.
This groundbreaking research has been published in the journal Nature.