Magmatic Records of Subduction Initiation and Early Building of the Kohistan Island Arc, Pakistan

ABSTRACT Subduction zones play a crucial role in Earth's physical and chemical dynamics, but their initiation and related magmatism remain poorly understood. This study presents new zircon U–Pb age, Hf–O isotope and whole‐rock major–trace element and Sr–Nd isotope data from the Kohistan arc in northern Pakistan, a well‐preserved Phanerozoic oceanic crustal arc. The Jaglot Group basalts are low‐K tholeiites similar to early Izu–Bonin–Mariana forearc basalts, representing the oldest volcanic stratigraphy of the Kohistan arc. The Matum Das tonalite, intruding the Jaglot Group at ~155 Ma, provides a new minimum age for subduction initiation. The rapid formation of new felsic crust shortly after subduction initiation challenges existing models and indicates the need for further research into early arc‐forming processes.