Scientists Discover How Volcanic Gold Deposits Form

Scientists Discover Key to Gold Formation in Volcanoes

In a significant breakthrough, scientists have unraveled the mysterious mechanism behind the formation of rich gold deposits near volcanoes. The discovery of a rare gold-sulfur complex reveals the crucial role it plays in transporting gold from the Earth's mantle to the surface. This finding not only enhances our understanding of Earth’s deep processes but also holds the potential to revolutionize gold exploration and mining strategies.

Gold-bearing volcanic breccia rock formation from the San Juan Mountains, Colorado

The Gold-Sulfur Connection

Gold deposits near volcanic regions, particularly around the Pacific Ring of Fire, originate deep within Earth’s mantle—30 to 50 miles beneath the surface. While researchers have long known that magma carries gold upward, the precise mechanism behind this process was unclear. A study published in the Proceedings of the National Academy of Sciences has now confirmed the existence of a gold-trisulfur complex, a chemical compound critical for transporting gold from the mantle to surface magmas.

“This thermodynamic model is the first to demonstrate the presence of the gold-trisulfur complex under these specific conditions,” said Adam Simon, professor of earth and environmental sciences at the University of Michigan and co-author of the study. “It provides the most plausible explanation for the high concentrations of gold in certain subduction zones.”

The Role of Subduction Zones

Subduction zones, where one tectonic plate dives beneath another, are hotspots for gold deposits and volcanic activity. These regions, encircling the Pacific Ocean from New Zealand to Alaska and Chile, create the ideal conditions for forming gold-rich ore deposits.

When trisulfur ions, introduced by subducting plates, interact with mantle fluids, gold bonds with the trisulfur to form a highly mobile complex. This process, occurring under the mantle’s extreme pressures and temperatures, enables gold to migrate upward more efficiently than previously understood.

Implications for Gold Exploration

The discovery has significant implications for gold exploration and mining. By pinpointing subduction zones with conditions conducive to forming gold-trisulfur complexes, geologists can more effectively locate gold-rich deposits. This approach could enhance exploration efficiency and reduce environmental impacts.

the geological processes involved in the formation of volcanic gold deposits, showing how gold is transported from deep within the Earth to the surface through volcanic activity.

Diagram illustrating the interaction of slab-derived fluids with the mantle wedge in a subduction zone, showing oxidation processes, sulfur and gold mobility, and concentration with labeled depths for fore-arc and sub-arc settings.

“These results provide a robust understanding of why certain subduction zones produce exceptionally gold-rich deposits,” Simon explained. “This knowledge could guide future exploration efforts and benefit the mining industry.”

Global Gold Map

The study's findings also provide a global gold map, pinpointing subduction zones with the highest potential for gold-rich deposits. These zones encircle the Pacific, stretching from New Zealand to Japan, the western United States, and South America.

A Promising Future

The study not only deepens our understanding of gold formation but also underscores the importance of sustainable and targeted exploration. As researchers refine these models, the potential for further scientific and economic discoveries grows.

“The same processes that drive volcanic eruptions also create gold deposits,” Simon noted. “By combining these findings with existing studies, we can significantly improve exploration strategies and reduce their environmental footprint.”

This groundbreaking research highlights how scientific collaboration can solve Earth’s mysteries while opening new frontiers for resource development.