Migmatite marvels: Unveiling the mysteries of high-grade metamorphism in Qandol, Bulfat mountain, Kurdistan region of Iraq

In this paper, we introduce the migmatitic rocks in the Qandol area as a part of the Bulfat Igneous Complex (BIC) complex in the Zagros Suture Zone, northeast Iraq for the first time. The main protolith is mafic rocks which are preserved in some areas. Meanwhile, the partially melted parts (leucosomes) have a trondhjemite composition, with plagioclase being the dominant mineral phase. Geochemical analysis reveals that the leucosomes portion exhibits higher concentrations of Na2O and CaO, accompanied by lower levels of K2O, indicating a stronger association with calc-alkaline features. Meanwhile, the melanosome demonstrates a tholeiitic nature, attributed to its elevated content of compatible elements like Mg and Fe within the residual materials such as amphibole and pyroxene. The thermobarometry assessment indicates that the leucosome parts were crystallized at a temperature of 670 –700 °C and a pressure near 0.1 GPa. Furthermore, phase equilibrium modeling using the GeoPS software indicates initial melting has occurred at 790°C – 920°C and 0.1– 0.4 GPa. The estimating of the P-T of the present migmatite infers that the metamorphism has occurred at high temperature and low pressure either in the root of the mature arc or in a shear zone as a result of hot oceanic subduction beneath the Sanandaj-Sirjan Zone (SaSZ) in the late Cretaceous or younger. The presence of the high-T migmatite in the Zagros Sutures Zone without a clear relation to the sole metamorphism in the base of ophiolite members in the Qandol area would be much more useful to understand the tectono-magmatic processes in the pre- to syn-collision regime during the closer of the Neotethys ocean.