Scientists discover a hidden 100-million-year-old volcanic system
Scientists have uncovered a long-lost volcanic system in Iran that dates back roughly 100 million years, revealing a hidden chapter in Earth's tectonic history. The discovery sheds new light on the disappearance of an ancient ocean and the powerful geological forces that reshaped the Middle East.
Key points
- Scientists found evidence of a previously unknown volcanic system in northwestern Iran.
- The Azerbaijan Continental Magmatic Arc was active about 101 to 97 million years ago.
- The Siah Cheshmeh-Khoy-Misho-Tabriz Fault may mark a major tectonic boundary.
An international team led by Istanbul Technical University has identified remnants of a previously unknown volcanic system in what is now northwestern Iran. Named the Azerbaijan Continental Magmatic Arc, the system formed during the Late Cretaceous period, roughly 101 to 97 million years ago, according to research published in Geoscience Frontiers.
The discovery fills a gap in the region's geological history. Later tectonic deformation, erosion, burial beneath sedimentary basins, and a younger episode of volcanic activity during the Eocene obscured much of the evidence of the arc's existence.
How the arc was identified
Researchers examined volcanic and plutonic rocks from multiple locations across northwestern Iran, focusing on formations along the Siah Cheshmeh-Khoy-Misho-Tabriz Fault. They used zircon U-Pb geochronology to date the rocks, Hf isotope analyses to trace their sources, and whole-rock geochemistry to study their composition.
The results showed signatures consistent with continental arc magmatism, a process in which one tectonic plate sinks beneath another and generates magma that rises through the overlying continental crust.
This study shows that the magmatic history of northwestern Iran is more complex than previously recognized.
— Dr. Ali Mohammadi
What the findings suggest
The newly identified arc adds to the known history of Iran's ancient magmatic activity, which had largely centered on the Sananda-Sirjan Magmatic Arc and the Urumieh-Dokhtar Magmatic Arc. It suggests northwestern Iran experienced a separate episode of continental arc activity during the Late Cretaceous.
Researchers propose that the Siah Cheshmeh-Khoy-Misho-Tabriz Fault may mark a major tectonic boundary linked to changes in the ancient Neo-Tethys Ocean system. Those changes may have included slab rollback and the migration of volcanic arcs, which could explain why this episode of magma formation was relatively short.
