TEHRAN -- A new geological discovery in northwestern Iran is providing important insights into the country’s ancient tectonic history and the evolution of the Neo-Tethys Ocean. 
An international team of researchers, led by Istanbul Technical University (ITU), has identified evidence of a previously unrecognized Late Cretaceous continental magmatic arc in the region, offering a new perspective on how Iran’s geological landscape developed over millions of years.
The researchers have named this geological system the Azerbaijan Continental Magmatic Arc. Their findings reveal that northwestern Iran hosted a distinct phase of volcanic and magmatic activity approximately 101–97 million years ago, during the evolution of the Neo-Tethys Ocean, an ancient ocean whose eventual closure played a major role in shaping the geology of Iran and surrounding regions.
The study, published in the journal Geoscience Frontiers, highlights the importance of northwestern Iran in understanding the complex geological evolution of the Iranian Plateau and the wider West Asia.
Iran’s geological structure reflects a long history of ocean formation, continental movement, volcanic activity and tectonic collisions. Its magmatic history has traditionally been associated with two major geological systems: the Sanandaj–Sirjan Magmatic Arc and the Urmia–Dokhtar Magmatic Arc.
However, the latest research suggests that northwestern Iran preserves evidence of another distinct magmatic system that had previously remained unrecognized.
According to the study, the Azerbaijan Continental Magmatic Arc was active during the Late Cretaceous period, around 101–97 million years ago. Its geological traces were subsequently obscured by several processes, including tectonic deformation, erosion, sedimentary basin burial and younger volcanic activity during the Eocene epoch.
These geological changes made it difficult to identify the original extent and significance of the ancient magmatic system.
To investigate the region’s geological history, researchers examined volcanic and plutonic rocks 
from several locations across northwestern Iran, particularly along the Siah Cheshmeh–Khoy–Misho–Tabriz Fault.
The research team applied advanced geological techniques, including zircon uranium-lead (U-Pb) dating, hafnium (Hf) isotope analysis and whole-rock geochemical investigations. These methods helped determine the ages, origins and chemical characteristics of the rocks.
The results revealed geological signatures consistent with subduction-related continental arc magmatism, supporting the existence of an ancient continental magmatic arc in northwestern Iran.
Dr. Ali Muhammadi, the study’s corresponding author at Istanbul Technical University, explained that the findings demonstrate that the magmatic history of northwestern Iran is considerably more complex than previously understood.
The research was conducted through international collaboration involving scientists from the Chinese Academy of Sciences, ETH Zurich in Switzerland, Karadeniz Technical University in Türkiye and Damghan University in Iran.
Beyond identifying a previously unknown magmatic system, the discovery could help researchers better understand the tectonic processes that shaped Iran.
The authors suggest that the Siah Cheshmeh–Khoy–Misho–Tabriz Fault may represent an important tectonic boundary linked to changes in the Neo-Tethyan subduction system. Processes such as slab rollback and the migration of magmatic arcs may have contributed to the development of this relatively short-lived geological episode.
The discovery also provides new evidence for reconstructing the evolution of the Neo-Tethys Ocean and its eventual closure, a process closely connected to the development of Iran’s present-day geological structure.
The identification of the Azerbaijan Continental Magmatic Arc adds an important chapter to Iran’s geological history. It demonstrates that ancient magmatic systems can remain hidden beneath younger geological formations and may only become recognizable through detailed geochronological, isotopic and geochemical research.
For Iran, the findings offer valuable new constraints on the evolution of its northwestern regions and their relationship with the broader Arabia–Eurasia collision zone.
More importantly, the discovery strengthens the understanding of how ancient oceans, subduction processes and continental movements contributed to the formation of the Iranian Plateau and the surrounding geological landscape.
By revealing evidence of a previously unknown Cretaceous magmatic arc, the research underscores the geological significance of northwestern Iran and opens new opportunities for investigating the region’s complex tectonic past.