A team of international researchers has made a groundbreaking discovery in northwestern Iran, uncovering evidence of a previously unknown volcanic system that dates back approximately 100 million years. This ancient system, known as the Azerbaijan Continental Magmatic Arc, was formed during the Late Cretaceous period and has been hidden from view due to later tectonic activity, erosion, and sedimentation. The researchers used advanced techniques, including zircon U-Pb geochronology, Hf isotope analyses, and whole-rock geochemistry, to determine the age and origin of the rocks. Their findings suggest that the volcanic system was active from around 101 to 97 million years ago, during a time when the ancient Neo-Tethys Ocean was undergoing significant changes. The discovery of the Azerbaijan Continental Magmatic Arc adds a new chapter to the geological history of northwestern Iran and the surrounding region. It also highlights the importance of the Siah Cheshmeh-Khoy-Misho-Tabriz Fault, which may mark a major tectonic boundary connected to changes in the ancient ocean system. The study's findings have significant implications for our understanding of Earth's geological history, particularly in the region of the Eastern Mediterranean, the Middle East, and Western Asia. The eventual disappearance of the ancient Neo-Tethys Ocean played a major role in shaping the modern landscapes of these regions. The discovery of the Azerbaijan Continental Magmatic Arc is a testament to the complexity and dynamic nature of Earth's geological history. It demonstrates the importance of continued research and exploration in uncovering the secrets of our planet's past.