Unlocking Japan’s Geological History: Insights from Volcanogenic Massive Sulfide Deposits
A recent study has advanced the understanding of Japan’s geological history through the analysis of rhenium-osmium (Re–Os) isotope geochronology applied to volcanogenic massive sulfide (VMS) deposits. This research specifically examines Besshi-type VMS deposits located in the Makimine and Shimokawa regions, providing significant insights into the timing of ridge subduction, a fundamental geological process affecting the Japanese landscape.
Challenges in Dating Tectonic Events
Historically, dating tectonic events has posed challenges due to the destruction of microfossil evidence resulting from intense heat. However, a research team, led by Professor Tatsuo Nozaki and including collaborators from multiple institutions, successfully utilized Re–Os isotope geochronology to overcome these obstacles. The team studied the formation of VMS deposits that typically occur near ocean floors, where volcanic activity is present along sediment-covered mid-ocean ridges.
Findings on VMS Deposits
The research findings indicate that the Makimine VMS deposit is approximately 89.4 million years old, while the Shimokawa VMS deposit dates back to about 48.2 million years ago. These temporal markers align with the subduction of the Izanagi-Pacific Ridge beneath Japan, as inferred from additional geological evidence, including the geologic contexts of surrounding sedimentary rocks and mineral associations.
Significance of Ridge Subduction
This study highlights the significance of understanding ridge subduction, a process that affects volcanic activity and metamorphism. The precise dating of VMS deposits not only enhances the knowledge regarding the geological evolution of Japan but also suggests potential opportunities for future mineral exploration. The research illustrates how the examination of geological history through mineral deposits can deepen the understanding of Earth’s tectonic processes and their effects on regional landscapes.
Publication and Future Research
The study was published in *Scientific Reports*, indicating a commitment to ongoing research in geochronology and tectonic activities in Japan, which may facilitate further exploration of geological resources and inform current challenges related to mineral deposits.
(Source: Waseda University)
