Whole rock geochemistry, zircon U-Pb dating and Sr-Nd and Hf isotopic studies of Cretaceous granitoids from Southern Pamir, Tajikistan: insights into Pamir Plateau formation

The Southern Pamir region, a critical part of the Alpine-Himalayan orogenic belt, exhibits a complex tectonomagmatic history that offers insights into the geodynamic evolution of the Pamir Plateau. This study presents comprehensive data on the Cretaceous granitoids from the Kyzylrabat area, including whole-rock geochemistry, zircon U-Pb geochronology and Sr-Nd-Hf isotopic analyses. The analysed granitoids are high-K calc-alkaline to shoshonitic, exhibiting A-type geochemical signatures. Zircon U-Pb ages range from 98.5 to 111.7 Ma, correlating well with contemporaneous volcanic activities. Isotopic data indicate a mixed magmatic origin involving a mantle-derived high-K magma and a crustal-derived felsic component. Petrogenetic analyses reveal co-magmatic trends and magma mixing processes, with geochemical evidence suggesting a mantle source metasomatized by subduction-related fluids. Geodynamic interpretations propose that the granitoids formed in an extensional back-arc setting during the northward subduction of the Shyok branch of the Neotethys Ocean. These findings provide critical constraints on the mid-Cretaceous tectonic and magmatic processes in the Southern Pamir, contributing to a deeper understanding of the orogenic plateau formation and evolution.