Magmatic evolution and formation of the giant Jiama porphyry-skarn deposit in southern Tibet

•SIMS U-Pb dating of Jiama intrusives brackets magmatic event related to Jiama porphyry-skarn mineralization in 1.3 Myr.•Zircon O-Hf isotopic compositions suggest Jiama ore-forming magmas were derived from melting of the newly formed Tibetan lower crust.•No significant magma mixing has been observed during the magmatic evolution from diorite to granite.