What's Happening?
Researchers from South Korea, Germany, and the United States have discovered a new phase of talc, a common clay found in the oceanic crust, which transforms into a superhydrated crystal capable of storing
approximately 31 percent water by weight. This transformation occurs at depths between 56 to 78 miles in cold subduction zones. The study, led by Yoonah Bang, PhD, at Yonsei University, reveals that talc can absorb extra water and expand by about 60 percent in salty, mildly basic water, trapping water between its sheets. This discovery suggests a reevaluation of subduction-related geochemistry and seismicity, as well as water transportation into the deep Earth.
Why It's Important?
The discovery of superhydrated talc crystals has significant implications for understanding Earth's deep water cycle. The ability of talc to store and later release large amounts of water could affect magma supply and the type of earthquakes recorded. This new phase of talc could shift where melting starts in subduction zones, potentially altering arc locations. Additionally, the release of water from talc at depth can lower rock melting points and weaken faults, influencing seismic activity. This research calls for future models to consider fluid chemistry alongside pressure and temperature, highlighting talc's potential role in Earth's water cycle.
What's Next?
Future research will likely focus on identifying the presence of the 15 angstrom phase in ancient high-pressure rocks and its smectite-like swelling behavior. Geophysicists may also search for conductivity or seismic fingerprints of extra water at these depths. The study suggests that talc could play a more significant role in Earth's deep water cycle than previously thought, prompting further investigation into its impact on subduction zone dynamics and seismic activity.
Beyond the Headlines
The discovery of superhydrated talc crystals opens new avenues for understanding the complex interactions between minerals and water in Earth's interior. This research highlights the importance of considering fluid chemistry in geological models, which could lead to more accurate predictions of seismic activity and magma formation. The findings also underscore the need for interdisciplinary collaboration in geoscience research, combining mineralogy, geophysics, and geochemistry to unravel Earth's deep processes.
